Co-Firing with Biomass

Co-Firing with Biomass
Glasnevin
Dublin 9
Ireland
t
f
e
w
+353 1 836 9080
+353 1 837 2848
[email protected]
www.sei.ie
Sustainable Energy Ireland is funded by the Irish Government
under the National Development Plan 2000-2006 with
programmes part financed by the European Union
04-RERDD-007-R-01
Co-Firing with Biomass
A report prepared for Sustainable Energy Ireland by
Executive Summary
Background
Biomass-based resources covered in this study include solid wood-based materials such as low-quality and/or
small-diameter pulpwood, harvesting residues, short rotation willow coppice, wood pellets and sawmill residues (bark, sawdust, chips) and other biomass-based materials such as straw, chicken litter, spent mushroom
compost, tallow and meat and bone meal.
Estimates for the theoretical and technical resource potential (supply) of each of these materials have been
made based on the best information available.
Theoretical and technical co-firing possibilities (demand) have been analysed for one coal-fired power plant
located in Moneypoint (pulverized combustion (PC) technology) and three peat-fired power plants: Edenderry,
Lough Ree Power and West Offaly Power representing each fluidised bed combustion (FBC) technology. The
Edenderry plant is in operation, whereas the Lough Ree and West Offaly Power plants are under construction.
The fuel properties of each biomass-based material were examined (except meat and bone meal and tallow
because they are not included in the scope of this study). Based on the chemical and physical properties of the
different materials and the worldwide operating experiences in electricity production with FBC and PC technologies the Consultant has estimated feasible co-firing potential (crossing point of demand curve and supply
curve) for wood-based materials only.
Theoretical and technical co-firing potential (demand)
At present, Moneypoint could theoretically co-fire high-quality sawdust and wood pellets up to approximately
560 GWh input per year in each unit (representing some 10% of total fuel use) without making any major modification investments in boiler and combustion technology. The technical co-firing possibilities are considerably
less i.e. 280 GWh/unit (5% of total fuel use) due to the bottlenecks in the plant’s existing fuel handling system
and equipment. In the future the recommended modification investment would be made in biomass gasification, which would allow the plant to use safely large quantities (max. 840 GWhfuel per unit, 15% of total fuel use)
of biomass-based fuels.
The current theoretical co-firing potential of Edenderry is 1,140 GWhfuel (50% of total fuel use) and the technical
potential 460 GWhfuel (20% of total fuel use). In the future, after modification investments, the technical co-firing
potential would increase to 690 GWhfuel (30% of total fuel use).
In the future West Offaly Power could technically co-fire other fuels with biomass to generate approximately
800 GWh per year and Lough Ree Power approximately 550 GWh per year. In both plants the maximum share
of biomass-based fuel would be limited to 30% of the total fuel use.
i
Future, 2010
With modification
investment
Technical
Current, 2003
Without modification
investments
Theoretical
Technical
Moneypoint
% of total
GWh,fuel / 1 unit
GWh,fuel / 3 unit
10 (direct)
560
1680
5 (direct)
280
840
15 (indirect)
840
2520
Edenderry
% of total
GWh,fuel / 1 unit
50
1140
20
460
30
690
West Offaly Power
% of total
GWh,fuel / 1 unit
30
800
Lough Ree Power
% of total
GWh,fuel / 1 unit
30
550
Table 1. Current (2003) theoretical and technical and future technical co-firing potential
Prices that power plants can afford to pay for biomass-based fuels
Equivalent prices of biomass-based fuels (no influence of emissions trading included) are expressed in the following table.
Without modification
investments
Current, 2003
EUR/MWh
Future, 2010
EUR/MWh
Modification
investment
included
Future, 2010
EUR/MWh
Effect of modification, 2010
Total investment
EUR 1 000
Effect on fuel price
EUR/MWh
Moneypoint, 1 unit
5
5.3
2,92
20 000
-2.38
Moneypoint, 3 units
5
5.3
2,92
60 000
-2.38
Edenderry
12.7
12,67
200
-0.03
West Offaly Power
11.3
12.7
12,67
200
-0.03
Lough Ree Power
12.7
12,67
200
-0.03
Table 2. Estimated equivalent prices for biomass-based fuels and the effect of possible modifications on
the fuel price
Moneypoint could buy biomass to be incinerated directly in existing boilers at a price of about EUR 5/MWh
today and EUR 5.3/MWh in the future. After possible modification investment in new gasification unit(s) the
biomass-based fuel paying capability would decrease to EUR 2.92/MWh.
The biomass-based fuel paying capability of Edenderry is today about EUR 11.3/MWh and in the future EUR
12.7/MWh assuming that no modification investments are made. The modification investment in a crusher
would decrease biomass-based fuel paying capability by some 3 cents per MWh of fuel.
West Offaly Power and Lough Ree Power have the same biomass-based fuel paying capabilities as Edenderry.
ii
Effect of emission trading on fuel prices and quantities to be traded
The effect of the prices of EUR 0, 10, 20 and 30/t of CO2 on the biomass-based fuel paying capability can be
summarized as follows:
Biomass-based fuel paying capability, €/MWhfuel
Time horizon
Price of CO2 in
emission trading, €/t
Modification
investment
Current, 2003
0
Future, 2010
0
Future, 2010
10
not included
8.5
16.6
16.6
16.6
Future, 2010
20
not included
11.7
20.5
20.5
20.5
Future, 2010
30
not included
15
24.4
24.4
24.4
Future, 2010
0
included
2.92
12.67
12.67
12.67
Future, 2010
10
included
6.12
16.57
16.57
16.57
Future, 2010
20
included
9.32
20.47
20.47
20.47
Future, 2010
30
included
12.62
24.37
24.37
24.37
West Offaly
Power
Lough Ree
Power
Moneypoint
Edenderry
not included
5
11.3
-
-
not included
5.3
12.7
12.7
12.7
Table 3. Effect of alternative carbon prices and modification investment on the biomass-based fuel paying capability
The quantities of the allowances that were allocated 1 to the power plants was 73.7% of their relevant GHG
emissions for the first emissions trading period (2005-2007). The allowances to be allocated for the second
emissions trading period (2008-2011) are not known. In this study it is assumed that the power plants will be
allocated less allowances for the second trading period than were allocated for the first period.
Plant
Fuel
t of CO2
Amount of CO2Amount of
free fuels to be
main fuel to be
used to achieve
replaced with
required emission
CO2-free fuel
savings
GWh fuel
1000 t
Amount of
CO2 to be
saved
Lough Ree Power
Peat
198 729
509
238
West Offaly Power
Peat
298 093
764
357
Edenderry
Peat
209 307
536
251
1 498 414
4 614
664
Moneypoint (three units) Coal
Table 4. Emission saving requirements by power plant
Environmental impact
The following table summarizes annual fuel consumptions and environmental impacts (including annual CO2
and SO2 emissions) of current theoretical and current and future technical biomass co-firing potentials at the
coal- and peat-fired power plants under review. In addition, their total annual coal, peat and biomass consumptions and emissions as well as emissions reductions have been shown.
1
Ireland’s National Allocation Plan, 2005-2007 as notified to the Commission on 31 March 2004
iii
Without biomass
co-firing
Coal: 5700
Biomass: 0
Moneypoint 1
Total: 5700
unit
CO2, Mt/a
1.85
SO2, t/a
8780
Coal: 17100
Fuel use, GWh Biomass: 0
Moneypoint 3
Total: 17100
units
CO2, Mt/a
5.55
SO2, t/a
26340
Peat: 2250
Fuel use, GWh Biomass: 0
Total: 2250
Edenderry
CO2, Mt/a
0.88
SO2, t/a
3570
(Peat: 2700)
Fuel use, GWh (Biomass: 0)
West Offaly
(Total: 2700)
Power
CO2, Mt/a
(1.05)
Fuel use, GWh
With biomass co-firing
Current theoretical Current technical
Future technical
(no modifications) (no modifications) (modifications included)
Coal: 5145
Biomass: 570
Total: 5715
1.67
8080
Coal: 15435
Biomass: 1710
Total: 17145
5.01
24240
Peat: 1125
Biomass: 1125
Total: 2250
0.44
2140
Coal: 5425
Biomass: 285
Total: 5715
1.76
8430
Coal: 16275
Biomass: 855
Total: 17130
5.28
25290
Peat: 1800
Biomass: 450
Total: 2250
0.70
3010
SO2, t/a
Lough Ree
Power
(4330`)
(Peat: 1800)
Fuel use, GWh (Biomass: 0)
(Total: 1800)
CO2, Mt/a
(0.70)
SO2, t/a
3250
Peat: 1260
Biomass: 540
Total: 1800
0.49
(2870`)
2150
Coal + peat: 19350 Coal + peat: 16560
Fuel use, GWh (23850`)
Total
Biomass: 0
(Moneypoint 3 CO2, Mt/a
6.43 (8.18)
units)
Reduction
SO2, t/a
29910 (37110)
Reduction
Coal: 4870
Biomass: 855
Total: 5725
1.57
7550
Coal: 14610
Biomass: 2565
Total: 17175
4.71
22650
Peat: 1575
Biomass: 675
Total: 2250
0.62
2720
Peat: 1890
Biomass: 810
Total: 2700
0.74
Biomass: 2835
Total: 19395
5.45
15.2%
26380
11.8%
Coal + peat: 18075 Coal + peat: 19335
Biomass: 1305
Total: 19380
5.98
7.0%
28300
5.4%
Biomass: 4590
Total: 23925
6.56
19.8%
30770
17.1%
Table 5. Fuel consumptions and environmental impacts of current theoretical and technical and future
technical biomass co-firing potentials at the power plants under review
In comparison to peat firing it is assumed that NOx emissions will not increase because the nitrogen content of
wood is lower than that of peat, which should reduce NOx emissions from Edenderry, Lough Ree Power and
West Offaly Power, where the majority of NOx originates from fuel nitrogen.
At Moneypoint there will probably be no changes in the current NOx emission level as a result of co-firing because the majority of NOx originates from air present in the combustion process. Based on operating experiences, it is, however, possible that the NOx emission level might decrease slightly due to the re-burning effect
caused by the product gas in the boiler
In comparison to coal and peat firing it is assumed that there will be no changes in dust emissions to air at
Moneypoint, Edenderry, Lough Ree Power and West Offaly Power. This is because the dust load before the dust
removal equipment reduces as the ash content of wood is lower than that of coal and peat. This should improve
the collection efficiency of dust removal equipment and thus at least in theory lower slightly the dust emissions
into the air.
iv
Biomass co-firing will also cause a small change in the fly and bottom ash composition, which has an impact on
the end use of fly ash at Moneypoint where it will be reused as a raw material in the cement factory. The current
requirements of the national standards in Ireland are that the loss of ignition shall not exceed 7% and the
source of ash must be coal. These requirements may prevent the use of fly ash derived from co-firing with biomass.
Indirect co-firing (gasification) of biomass will cause no changes in the fly and bottom ash composition because
ashes derived from the gasification and boiler plants do not mix with each other. Therefore, gasification has no
effect on the current end use of fly ash at Moneypoint where it will be reused as a raw material in the cement
factory.
The bottom ashes of the boiler and gasification plants at Moneypoint and both ashes (fly and bottom) at
Edenderry, Lough Ree Power and West Offaly Power will be transported to the ash disposal areas where the
small changes in the ash composition are not so critical and should have no direct effect on this kind of end use.
Supply
Total theoretical indigenous biomass resource potential in 2003 was about 13.5 TWh (5.5 Mt fresh), the amount of
which is predicted to increase to 15.2 TWh (6.7 Mt fresh) by the year 2010. This amount of fuel in 2010 would be
sufficient to fuel an electricity production plant with a capacity of 665 MWe (operating hours: 7500 h/a, efficiency: 0.37). The share of wood-based biomass was 6.2 TWh (3.4 Mt) in 2003 and is expected to be 8.5 TWh (4.7
Mt) in 2010. Wood–based biomass would be sufficient for an electricity production capacity of 417 MWe.
Technical biomass resource potential was 2.2 TWh fuel (0.9 Mt fresh, 110 MWe) in 2003 and is expected to be 3
TWh fuel (1.4 Mt fresh, 150 MWe) in 2010. The share of wood-based biomass was 1.1 TWh (0.6 Mt) in 2003 and is
projected to be 1.9 TWh (1 Mt) in 2010.
The most promising wood-based biomass resource potential in the year 2010 includes pulpwood (low-quality
and small-diameter roundwood) with 728 GWhfuel technical availability, followed by sawmill residues (624
GWhfuel), harvesting residues (443 GWhfuel) and short rotation coppice (SRC) willow (99 GWhfuel).
v
1000 t/a 1000 s-m3/a
PJ (fuel)
fresh
fresh
Pulpwood
Theoretical
2003
1 209
Technical
2003
132
Theoretical
2010
1 596
Technical
2010
414
Sawmill residues (bark, sawdust, chips)
Theoretical
2003
1 174
Technical
2003
266
Theoretical
2010
1 223
Technical
2010
315
Harvesting residues
GWh
(fuel)
Electricity
MWe
1 343
146
1 773
459
7,7
0,8
10,1
2,6
2 128
231
2 808
728
105
11
139
36
1 305
296
1 359
350
8,2
1,9
8,6
2,2
2 292
528
2 389
624
113
26
118
31
Theoretical
2003
1 029
1 143
6,5
1 810
89
Technical
2003
216
240
1,4
380
19
Theoretical
2010
1 200
1 333
7,6
2 111
104
Technical
2010
Meat and Bone Meal
Theoretical
2003
252
280
1,6
443
22
150
0
2,2
613
30
Technical
Theoretical
Technical
Chicken litter
Theoretical
Technical
Theoretical
Technical
2003
2010
2010
75
135
68
0
0
0
1,1
2,0
1,0
306
552
276
15
27
14
2003
2003
2010
2010
137
35
137
35
1,2
0,3
1,2
0,3
340
86
340
86
17
4
17
4
1 155
99
57
5
5 328
266
5 001
400
263
13
247
20
199
63
199
63
10
3
10
3
775
367
705
328
38
18
35
16
13 484
2 230
15 259
3 048
665
110
753
150
6 230
1 140
8 462
1 894
307
56
417
93
Short Rotation Coppice (Willow)
Theoretical
2003
Technical
2003
Theoretical
2010
669
743
4,2
Technical
2010
57
64
0,4
Straw
Theoretical
2003
1 428
19,2
Technical
2003
71
1,0
Theoretical
2010
1 340
19,2
Technical
2010
107
1,4
Spent Mushroom Compost
Theoretical
2003
290
0,7
Technical
2003
93
0,2
Theoretical
2010
290
0,7
Technical
2010
93
0,2
Tallow
Theoretical
2003
78
2,8
Technical
2003
37
1,3
Theoretical
2010
71
2,5
Technical
2010
33
1,2
TOTAL RESOURCE POTENTIAL
Theoretical
2003
5 495
3 791
49
Technical
2003
924
682
8
Theoretical
2010
6 661
5 208
56
Technical
2010
1 373
1 153
11
WOOD-BASED BIOMASS RESOURCE POTENTIAL
Theoretical
2003
3 412
3 791
22,4
Technical
2003
613
682
4,1
Theoretical
2010
4 687
5 208
30,4
Technical
2010
1 038
1 153
6,8
Table 6. Theoretical and technical indigenous biomass-based fuel resource potential (2003, 2010) with
estimated electricity production capacity potential
vi
Pulp
wood
Saw
resid
Forest
resid
Straw
Tallow
MBM
Chicken SRC
litter
willow
SMC
2010
2003
2010
2003
2010
2003
2010
2003
2010
2003
2010
2003
2010
2003
2010
2003
Technical Resurce Potential
Theoretical Resource Potential
2010
2003
0
500
1 000
1 500
2 000
2 500
GWh fuel
Figure 1. Theoretical and technical indigenous biomass-based fuel resource potential in 2003 and in
2010
In addition to indigenous biomass resources, substantial amounts of wood pellets could be imported to Ireland.
Feasible level of co-firing
General
The feasible level of co-firing has been evaluated for wood-based fuel only (pulpwood, harvesting residues,
sawmill residues, short rotation coppice and wood pellets) because of its current suitability for co-firing with
peat or coal in electricity production with FBC and PC technology.
The power plants in this study would not invest in stationary chippers because biomass-based fuel intake to the
power plant would be in the form of chips, dust, bark or pellets. Comminution of pulpwood, harvesting residues
and SRC willow would take place at the source, at the roadside or landing, or at a terminal.
The power plants also compete for the same biofuel resources available from a reasonable transportation distance. This is especially true for Edenderry, West Offaly Power and Lough Ree Power, which would face tough
competition from each other.
vii
EUR/t of CO2
Moneypoint
1 unit
Moneypoint
3 units
Edenderry
West Offaly
Power
Lough Ree
Power
Without modification
2003
2010
0
0
10
20
Demand 1) 280
280 280 280
Supply 2) 0
0
0
10
3)
Feasible 0
0
0
10
Demand 1) 840
840 840 840
Supply 2) 0
0
0
10
Feasible 3) 0
0
0
10
1)
Demand 460
460 460 460
Supply 2) 170
265 845 1528
3)
Feasible 170
265 460 460
Demand 1)
Supply 2)
Feasible 3)
Demand 1)
Supply 2)
Feasible 3)
30
280
58
58
840
58
58
460
2751
460
Modification investments included
2010
0
10
20
30
840
840
840
840
0
0
0
132
0
0
0
132
2520 2520 2520 2520
0
0
0
132
0
0
0
132
690
690
690
690
260
828
1497 2696
260
690
690
690
800
800
800
800
372
877
1581 2167
372
800
800
800
550
550
550
550
382
1058 1623 2069
382
550
550
550
Table 7. Feasible level of co-firing at different carbon prices of EUR 0, 10, 20 and 30/t of CO2.
1) Demand: Total technical co-firing potential (Technical biofuel demand at the power plant, GWhfuel)
2) Supply: Technical biomass-based fuel supply potential at a given price level, GWhfuel
3) Feasible: Feasible co-firing level taking into account restrictions in demand and supply, Gwhfuel
Moneypoint
Technically Moneypoint could co-fire directly wood pellets and sawdust to generate approximately 280 GWh
per year in each of the three units without making any major modifications. After possible modification (a new
gasification plant) Moneypoint could increase indirect co-firing to some 840 GWh per year in each unit. However, the restricting factor for large-scale co-firing would be the lack of suitable fuels at a competitive price. In
case Moneypoint uses direct combustion (no modification), the feasible supply potential of suitable fuels would
be only 10 GWh (EUR 20/t of CO2) and 58 GWh (EUR 30/t of CO2), the only fuel type available being sawdust.
The new gasification plant could use a larger variety of wood-based fuels but still the limiting factor would be
the availability of competitive biomass-based fuels. Only some 132 GWh of fuels consisting of pulpwood and
harvesting residue chips and sawdust would be available at competitive prices assuming that the carbon price
in emissions trading would be EUR 30/t.
Edenderry
Edenderry could co-fire directly (technical co-firing potential) wood chips, wood pellets, bark and sawdust to
generate approximately 460 GWh per year without making any major modifications. After possible modification
(a crusher with auxiliary systems and equipment to deal with oversize wood particles from the screen)
Edenderry could increase direct co-firing to approximately 690 GWh per year.
However, the restricting factor for large-scale co-firing today and in the year 2010 in the case of zero emissions
trading value for CO2 would be the lack of affordable wood-based fuels. This would limit the feasible co-firing
potential to 170 GWhfuel today and to approx. 260 GWhfuel in the year 2010.
viii
If the CO2 value in emissions trading is EUR 10, 20 or 30/t, Edenderry could purchase required amounts of woodbased biomass in order to meet the demand of co-firing (technical potential: 460 GWh without modification
and 690 GWh with modification investment), assuming that West Offaly Power and Lough Ree Power would not
aim at the same biomass resources as Edenderry.
West Offaly Power
West Offaly Power could co-fire directly wood chips, wood pellets, bark and sawdust to generate approx. 800
GWh per year. This technical co-firing potential has been estimated assuming that possible plant modification
investment (a crusher with auxiliary systems and equipment to deal with oversize wood particles from the
screen) would be required in the future.
The restricting factor for large-scale co-firing in the year 2010 in the case of zero emissions trading value for CO2
would be the lack of affordable wood-based fuels. This would limit the feasible co-firing potential to about 370
GWhfuel in the year 2010. If the CO2 value in emissions trading would be EUR 10, 20 or 30/t, West Offaly Power
could purchase required amounts of wood-based biomass in order to meet the demand of co-firing (technical
potential: 800 GWh), assuming that Edenderry and Lough Ree Power would not aim at the same biomass resources as West Offaly Power.
Lough Ree Power
Lough Ree Power could co-fire directly wood chips, wood pellets, bark and sawdust to generate approx. 550
GWh per year. This technical co-firing potential has been estimated assuming that possible plant modification
investment (a crusher with auxiliary systems and equipment to deal with oversize wood particles from the
screen) would be required in the future.
The restricting factor for large-scale co-firing in the year 2010 in the case of a zero emission trading value for
CO2 would be the lack of supply of affordable wood-based fuels. This would limit the feasible co-firing potential
to about 380 GWhfuel in the year 2010. If the CO2 value in emissions trading is EUR 10, 20 or 30/t, Lough Ree
Power could purchase required amounts of wood-based biomass in order to meet the demand of co-firing
(technical potential: 5 500 GWh), assuming that Edenderry and West Offaly Power would not aim at the same
biomass resources as Lough Ree Power.
Environmental impact
The following table summarizes the annual fuel consumptions and environmental impacts (including annual
CO2 and SO2 emissions) of current and future feasible biomass co-firing potentials at the coal- and peat-fired
power plants under review. In addition, their total annual coal, peat and biomass consumptions and emissions
as well as emissions reductions have been shown.
ix
Without biomass
co-firing
Moneypoint 1
unit
Fuel use, GWh
CO2, Mt/a
SO2, t/a
Fuel use, GWh
Moneypoint 3
units
CO2, Mt/a
SO2, t/a
Fuel use, GWh
Edenderry
CO2, Mt/a
SO2, t/a
West Offaly
Power
Fuel use, GWh
CO2, Mt/a
SO2, t/a
Lough Ree
Power
Coal: 5700
Biomass: 0
Total: 5700
1.85
8780
Coal: 17100
Biomass: 0
Total: 17100
5.55
26340
Peat: 2250
Biomass: 0
Total: 2250
0.88
3570
(Peat: 2700)
(Biomass: 0)
(Total: 2700)
(1.05)
With biomass co-firing
Current feasible
Future feasible
(no modifications) (modifications included)
Coal: 5700
Biomass: 0
Total: 5700
1.85
8780
Coal: 17100
Biomass: 0
Total: 17100
5.55
26340
Peat: 2080
Biomass: 170
Total: 2250
0.81
3360
Coal: 5570
Biomass: 135
Total: 5705
1.81
8610
Coal: 16970
Biomass: 135
Total: 17105
5.51
26170
Peat: 1575
Biomass: 675
Total: 2250
0.62
2720
Peat: 1890
Biomass: 810
Total: 2700
0.74
CO2, Mt/a
(4330`)
(Peat: 1800)
(Biomass: 0)
(Total: 1800)
(0.70)
3250
Peat: 1260
Biomass: 540
Total: 1800
0.49
SO2, t/a
(2870`)
2150
Fuel use, GWh
Coal + peat: 19350 Coal + peat: 19180 Coal + peat: 21695
Fuel use, GWh
Total
(Moneypoint 3 CO2, Mt/a
units)
Reduction
SO2, t/a
Reduction
(23850`)
Biomass: 0
6.43 (8.18)
Biomass: 170
Total: 19350
6.36
1.1%
29700
0.7%
29910 (37110)
Biomass: 2160
Total: 23855
7.36
10.0%
34290
7.6%
Table 8. Fuel consumptions and environmental implications of current and future feasible biomass cofiring potentials at power plants
Recommendations
It is recommended by the Consultant that only one of the peat-fired power plants would start to co-fire. As soon
as co-firing and competitive supply of wood-based fuel has become established practice, another peat-fired
power plant would start co-firing.
The Consultant recommends that co-firing with biomass could be commenced at Edenderry (wood chips and
saw dust) and at Moneypoint (sawdust and possibly wood pellets if available at competitive price).
It should also be noted that any move to co-fire biomass in the peat-fired power stations in the shorter term will
require agreement with Bord na Móna due to the 15-year fuel purchase agreements in force.
x
Technical and feasible co-firing and related CO2e reduction potential
The pilot phase of the EU emissions trading scheme is due to commence in January 2005. In compliance with its
obligations, Ireland notified its National Allocation Plan (pilot phase 2005-2007) to the European Commission
on 31st March 2004. Based on the National Allocation Plan as notified to the Commission, the emission allocated to the traded sector for 2005-2007 is 67.5 Mt CO2e, or 98.2% of the base case scenario GHG emissions
from the sector for that period. Within the entity level allocation, the power plants under review in this study
have been allocated allowances which are 73.7% of their ‘relevant emission’1. Therefore, the power plants will
be required to reduce their greenhouse gas emissions or to purchase carbon credits, amounting to a total of
2,204,543 t CO2e (~1,498,000 t from coal-fired generation and ~706 000 t from peat-fired generation).
The study commissioned by the Irish Government to determine the share of national greenhouse gas emissions
for emissions trading in Ireland 2 estimates that the allocated emissions to the traded sector for the 2008-2012
(Kyoto) period will represent an average of 84% coverage of the traded sector’s base case scenario GHG emissions for this period. The entity level allocations have not been announced for this second “Kyoto” phase of the
emissions trading scheme, and therefore the allocation to individual power plants for this period is not known.
The feasible potential for co-firing with biomass in the solid-fuel burning power plants, together with the potential GHG savings, are shown in Table 9 below, and graphically in Figure 2.
Peat
Coal
Total
GWh
t CO2e
GWh
t CO2e
GWh
t CO2e
170
66 353
0
0
170
66 353
EUR 0/t of CO2e
460
179 544
0
0
460
179 544
EUR 10/t of CO2e
1 100
429 343
0
0
1 100
429 343
EUR 20/t of CO2e
1 700
663 530
0
0
1 700
663 530
EUR 30/t of CO2e
2 040
796 236
132
42 863
2 172
839 099
2003
EUR 0/t of CO2e
2010
Table 9. The feasible level for co-firing with biomass and related GHG savings
1
For Edenderry Power Plant and Moneypoint Generating Station, the relevant emission was taken to be the average greenhouse gas emission in the period 2002-2003. For Lough Ree Power and West Offaly Power Plants, the
relevant emissions were set at the predicted greenhouse gas emissions.
2
ICF Consulting, Byrne Ó Cléirigh Ltd., February 2004, Determining the Share of National Greenhouse Gas
Emissions for Emissions Trading in Ireland, Final Report, submitted to the Department of the Environment, Heritage and Local Government, Ireland.
xi
GWhfuel
2003
2010
Co-firing with coal
4500
4000
3500
3000
Technical Co-firing potential
2500
10 €/t of CO2
1000
Feasible Co-firing with
alternative CO2 -prices
500
0 €/t of CO2
Co-firing with peat
20 €/t of CO2
1500
INDIGENOUS
BIOMASS SUPPLY
30 €/t of CO2
2000
Biomass imports
0
Substitution for peat
0
0,1
Feasible potential for
CO2 -reduction with
alternative CO2 prices
0,2
0,3
0,4
0 €/t of CO2
10 €/t of CO2
0,5
0,6
20 €/t of CO2
0,7
0,8
30 €/t of CO2
1
Substitution for coal
0,9
Technical potential for CO2 -reduction
1,1
1,2
1,3
1,4
1,5
1,6
1,7
Mt of CO2
2003
2010
Figure 2. Technical and feasible co-firing and related CO2e reduction potential in the studied power
plants with alternative CO2e emissions trading price levels.
The potential for co-firing at the Moneypoint coal-fired power plant is very low. The analysis indicates that it
would not be economically sensible for the plant to co-fire with biomass under most scenarios considered. Even
under the emissions trading scenario where it is assumed that the clearing price for carbon credits under the EU
ETS scheme is EUR 30/t CO2e, the total feasible GHG savings, which could be achieved from biomass correspond
to less than 1% of the annual GHG emissions from the plant. On this basis alone, it is unlikely that Moneypoint
would opt to use co-firing biomass in their strategy to meet requirements under the National Allocation Plan.
xii
The potential for emissions savings at the peat-fired plants is more significant. Assuming a carbon creditclearing price of EUR 10/t CO2e, as indicated by the forward market price for EUA for the pilot phase of the EU
ETS, the feasible potential for GHG savings is estimated to be 429 343 t CO2e at the peat-fired plants under review by 2010. This corresponds to approximately 16% of the annual emissions from these peat-fired plants. The
potential would be even higher at higher clearing prices of carbon credits. While the feasible potential for 2007
may be somewhat lower than that projected for 2010, the analysis suggests that co-firing with biomass could
help to meet a significant proportion of the peat-fired plants’ obligations under the EU ETS.
Economic implications
At present, the coal- and peat-fired power plants have a unique role in the economic life of Ireland. The production of peat is a protected activity and the costs of electricity generation from it are recovered under a Public
Service Obligation, as a result of which any substitution of biomass for peat needs to consider the employment
implications. However, the production of biomass creates new job opportunities in production and transportation.
When taking into account a few lost jobs in peat production and transportation as a result of biomass co-firing it
can be concluded that the net change in the number of jobs is negligible. Moreover, co-firing of biomass at the
coal- and peat-fired power plants is not expected to have any employment effect on the operation and maintenance of these plants.
xiii
Table of Contents
1
Introduction
1
2
Review Existing Knowledge
2
Characterization and Properties of Biomass
2
2.1.1
Wood (forest wood, industrial wood residues, energy plantations)
3
2.1.2
Straw
5
2.1.3
Spent mushroom compost
5
2.1.4
Chicken litter
6
2.1
2.2
2.3
2.4
2.5
Fuel Handling and Pre-Treatment
6
2.2.1
Fuel receiving and sampling
6
2.2.2
Fuel screening
6
2.2.3
Fuel conveying and storing
7
2.2.4
Fuel feeding into the boiler
7
2.2.5
Control, fire and occupational safety
7
Types of Co-Firing Applications
7
2.3.1
Fluidised bed combustion
7
2.3.2
Pulverised combustion
9
2.3.3
Grate combustion
10
2.3.4
Gasification
11
Operational Experiences from Existing Co-Firing Power Plants
12
2.4.1
Finnish cast study o power plant availability
12
2.4.2
Pulverised coal-fired boilers
12
2.4.3
Grate boilers
14
2.4.4
Fluidised bed boilers
16
2.4.5
Gasification
17
Emissions to Air
19
1
2.6
2.5.1
CO2 emissions
19
2.5.2
SO2 emissions
19
2.5.3
NOX emissions
20
Boiler Plant Operation in CO-Firing
20
2.6.1
Blending of coal and biomass
20
2.6.2
Slagging and fouling
22
2.6.3
Challenges and restrictive factors
23
2.6.4
Advantages
24
2.6.5
Large-scale power production
24
2.7
Ongoing Research and Development within the EU
25
2.8
Summary and Conclusions
25
Theoretical and Technical Co-Firing Possibilities in Ireland
28
Description of Power Plants Under Review
28
3.1.1
Moneypoint coal-fired power plant
28
3.1.2
Edenderry peat-fired power plant
32
3.1.3
Lough Ree power peat-fried power plant
36
3.1.4
West Offaly power peat-fired power plant
39
3.1.5
Agreements, obligations, planning permissions, licensees
42
3
3.1
3.2
3.3
Defining Theoretical and Technical Co-Firing Potential by Plant
42
3.2.1
Current theoretical maximum potential (based on combustion and
boiler technology)
42
3.2.2
Current technical co-firing potential (based on plant technology and
performance, current operational systems and equipment)
43
3.2.3
Estimating technical co-firing potential in the future
44
3.2.4
Summary
46
Defining Biomass Fuel Paying Capability by Plant
2
47
4
4.1
5
5.1
5.2
3.3.1
Current situation
47
3.3.2
Future situation with fuel / energy-production subsidies / taxes and
emission trading
47
Environmental Impact
51
Boiler Plant Performance and Emissions
51
4.1.1
Without biomass co-firing
51
4.1.2
With biomass co-firing
51
Economic Implications
56
Present Situations
56
5.1.1
Peat production and usage
56
5.1.2
Peat transportation
56
5.1.3
Employment impact of peat
56
5.1.4
Role of peat
56
Co-Firing with Biomass
57
Theoretical and Technical Biomass Supply Potential
58
6.1
Summary
58
6.2
Availability of Wood-Based Biomass
60
6.2.1
Forest resource
60
6.2.2
Defining sawmill residues potential (chips, sawdust, bark)
61
6.2.3
Defining pulpwood (small-diameter roundwood) potential
69
6.2.4
Defining forest residues potential
73
6.2.5
Defining short rotation coppice plantations (willow) potential
77
6.2.6
Overseas trading of biofuels (wood pellet)
78
6
6.3
Availability of Straw
81
6.4
Availability of Chicken Litter
84
6.5
Availability of Spent Mushroom Compost
88
6.6
Availability of Other Biomass Types
92
3
6.7
7
7.1
Technical Applicability of Available Biomass to Co-Firing in Power Generation
98
Estimating Feasibile Level for Co-Firing with Biomass
99
General
99
7.1.1
Summary of the technical supply potential
99
7.1.2
Summary of the technical co-firing potential
99
7.2
Current Feasible Co-Firing Level
101
7.3
Future Feasible Co-Firing Level
104
7.3.1
Without modification investments
104
7.3.2
With modification investments
107
7.4
Summary
108
Institutional Mechanisms to Support Biomass and Biomass-Based Electricity Production in Ireland
112
8.1
Background
112
8.2
Existing Policy
112
8.2.1
Support for peat generation
112
8.2.2
Support for renewable energy generation
112
8.2.3
Public Service Obligation (PSO)
113
8.2.4
Research and development policy
113
8
8.3
8.4
Future Policy
114
8.3.1
Carbon energy taxation
114
8.3.2
Emissions trading
114
8.3.3
RES-E Directive
114
Additional Potential Mechanisms to Boost Co-Firing Potential
4
115
APPENDICES
1.
2.
3.
4.
5.
Biomass resource and co-firing definitions
Geographical location of power plants, panel board mills, sawmills
Developing technology for large-scale production of forest chips
Institutional framework in Finland
Current and future technical biomass-based fuel availabilities
5
1 Introduction and Study Objectives
Sustainable Energy Ireland (SEI) is commissioning a series of studies to assist the Irish Government in the formulation and implementation of Ireland’s future policy and programmes on renewable energy for the period beyond 2005, taking into account future climate change commitments and the European Directive “On the promotion of electricity produced from renewable energy sources in the internal electricity market" (2001/77/EC).
This includes work, which is intended to contribute to the development of a strategy for biomass for energy, or
bioenergy, which is to be prepared by the Department of Communications, Marine and Natural Resources.
One of the aspects in the development of biomass is how much it can be co-fired in electricity generating plants
fuelled by coal or peat. The objective of this study is to examine the effects of co-firing with biomass.
Electrowatt-Ekono Oy with Byrne Ó Cléirigh as a sub-consultant was awarded the contract to carry out the
study.
The ultimate objective of the study is to investigate and quantify the economic, technical and environmental
costs and benefits of co-firing biomass with traditional solid fuels in electricity generation in Ireland.
The main reasons for the growing international interest in utilising renewable fuels are the objectives of promoting the use of renewable fuels in line with the statements in the European Commission’s White Paper and of
meeting emission limits and targets set by the EU directives. Emissions allowance trading may also pose new
challenges to power producers in the future. It can already be stated with great confidence that power producers will have to cope with an increasing number of EU-level regulations concerning emission levels in general,
and especially greenhouse gas emissions. Usually these regulatory actions aim at favouring the use of biomass.
On the one hand, co-firing, which is defined as simultaneous combustion of different fuels in the same boiler,
provides one alternative to achieve emission reductions. This is not only accomplished by replacing fossil fuel
with biomass, but also as a result of the interaction of fuel reactants of different origin, e.g. biomass and coal. On
the other hand, utilisation of solid biomass sets new demands for boiler process control and boiler design, as
well as for combustion technologies, fuel blend control and fuel handling systems.
1
2 Review existing knowledge
2.1
Characterization and properties of biomass
The characteristics of biomass are very different from those of coal. The content of volatile matter in woodbased biomass is generally close to 80%, whereas in coal it is around 30%. Wood char is highly reactive, which
results in complete combustion of wood fuels in fluidised bed combustion. Nitrogen and sulphur contents of
wood are low. This implies that blending wood biomass with coal lowers emissions simply because of dilution.
Further, one important difference between coal and biomass is the net calorific value. Biomass fuels often have
high moisture content, which results in a relatively low net calorific value.
The influence of fuel characterisation on boiler design is shown in Figure 3 and typical properties of solid fuels
in Table 10.
WOOD WASTE
FIBRE RESIDUE
FOREST CHIPS
Figure 3. Influence of fuel characterisation on boiler design.
The following table summarizes typical properties of the most potential biomass types available in Ireland by
2010. In general, the energy properties of each biomass type vary a lot depending, for example, on the climatic
and soil conditions, biomass production/cultivation method, harvesting technology and the further processing
method used to process biomass to ready fuel. The values presented are based on the biomass utilization experiences in the European countries. One exception is spent mushroom compost (SMC), which, according to the
Consultant’s knowledge, has not been used for electricity production. The fuel properties of SMC have not been
analysed and the values presented in the table are estimates made by the Consultant.
2
Forestry
residues
Logging
residue
1)
chips
Moisture content, w-%
50-60
(fresh)
Net calorific value in
18.5-20
dry matter, MJ/kg
Bulk density as
250-400
received, kg/loose m3
Ash content in dry
1-3
matter, w-%
C, % (d)
48-52
H, % (d)
6-6.2
0.3-0.5
N, % (d)
O, % (d)
40-44
S, % (d)
< 0.05
Cl, % (d)
0.01-0.04
K, % (d)
0.1-0.4
Ca, % (d)
0.2-0.9
Industrial wood residues
Sawmilling wastes
Sawdust
2)
2)
Bark
Chips
2)
Densified
wood
Pellets
Short rot.
coppice
Agricultural residue
Chicken Mushroom
willow chips Straw 1) litter (fresh) compost
1)
3)
3)
(fresh)
Meat &
Bone
3)
Meal
Tallow
MBM
45-60
45-65
45-60
7-12
50-60
17-25
35
68
8
10
18.5-20
18.5-23
19-19.2
19-20
18.4-19.2
17.4
15
12.1-13.7
16.2
40
250-350
250-400
250-350
650-700
150
50-70
400
319
0.5-0.8
0.5-2
0.4-0.5
0.5
1.1-4
5
7
35
28.3
48-50
5.4-6.4
0.1-0.5
38-42
< 0.05
< 0,01
51-66
5.7-6.8
0.3-0.8
24-40
< 0.05
<0,01-0,03
48-50
6.2-6.4
0.1-0.5
38-42
< 0.05
< 0,01
3.2
3.1
2.55
5.8
7.52
0.3
1.59
0.38
6.2-6.4
0.1-0.5
< 0.05
47-51
45-47
5.8-6.7
5.8-6
0.2-0.8
0.4-0.6
40-46
40-46
0.02-0.1 0.05-0.2
0.01-0.05 0.14-0.97
0.2-0.5
0.68-1.3
0.2-0.7
0.1-0.6
980
0.1
2.5
7.25
1) CEN 335 - Solid biofuels, Fuel specifications and classes, March 2003.
2) ALTENER II: Wood fuels basic information pack, March 2000
3) Dry agricultural resource study
Table 10. Typical properties of biomass-based fuels
2.1.1
Wood (forest wood, industrial wood residues, energy plantations)
Wood fuel resources available for co-firing are diverse: sawdust, cutter chips, demolition wood, recycled wood,
bark, logging residue chips, or even more refined biomass, such as pellets. Fluidised bed and grate boilers can
use any type of wood fuel, whereas pulverised fuel boilers are more selective.
Co-firing of wood and coal has been demonstrated in several pulverised fuel plants in Europe and the United
States. The results have been promising - boiler efficiencies have not suffered considerably. However, the maximum share of wood in the fuel blend has been small, only about 5-10%.
The properties of wood-based biomass set high requirements for power plant operation. These properties include total ash content, ash melting behaviour and the chemical composition of ash. Alkaline metals that are
usually responsible for fouling of heat transfer surfaces are abundant in wood fuel ashes and will be easily released in the gas phase during combustion. In biomass fuels, these inorganic compounds are in the form of salts
or bound in the organic matter, but in peat, for example, inorganic matter is bound mostly in silicates, which are
more stable at elevated temperature. The elemental composition of ash (alkali metals, phosphorous, chlorine,
silicon and calcium) and the chemical concentration of the compounds affect ash-melting behaviour.
During combustion the behaviour of biomass fuel is influenced by the presence of other fuels. Even a small
concentration of chlorine in the fuel can result in the formation of harmful alkaline and chlorine compounds on
boiler heat transfer surfaces. This can be prevented by co-firing fuels such as containing sulphur and aluminium
silicate peat or coal with chlorine bearing fuels.
Residues from the wood-processing industry form one specific group of risky wood fuels. By-products, such as
plywood and particle board cuttings are attractive fuels for energy producers: the fuel price may be even negative, as this material should otherwise be taken to a landfill site. But glue, coating and shielding materials may
cause bed agglomeration, slagging, and fouling and unexpectedly high flue gas emissions.
3
General aspects of wood as a fuel
The characteristics affecting the properties of wood as a fuel are: heating value, chemical composition, moisture
content, density, hardness, the amount of volatile matters, the amount of solid carbon, ash content and composition, the melting behaviour of ash, the slagging behaviour of ash and the amount of impurities, dust and fungi
spores.
Wood fuel chips, for instance, are often made of various tree species with various proportions of wood, bark,
foliage, branches, buds, and even cones. This causes variation in the fuel properties.
Approximately one half of fresh, just fallen tree is water. The other half consists of dry matter of wood, approximately 85% of which consists of volatile matters, 14.5% of solid carbon and 0.5% of ash. When wood is combusted, its components will change into steam of water (H2O), carbon dioxide (CO2), nitrogen oxides (NO2), sulphur oxides (SO2) and ash. Wood has practically no sulphur at all, as its share in wood is 0.05% at the highest.
The average chemical content of wood fuels is shown in Table 11.
Table 11. Average Chemical Contents of Wood Fuels
Wood in its various forms is the most widely used biomass-based fuel in energy production.
The moisture content of fresh wood fuel varies from 50 to 60 per cent of the weight of the total mass. The effect
of moisture content on the heating value of wood is defined in Figure 4.
Figure 4. The effect of moisture content on the heating value of wood (kWh/kg)
The calorific heating value of dry matter does not vary a great deal from one tree species to another (18.7 -21.9
MJ/ kg), but it is slightly higher in coniferous species than in deciduous tree species. This is caused by the higher
lignin and resin contents in coniferous species.
The ash contained in wood comes primarily from soil and sand absorbed in the bark. A minor proportion also
comes from salts absorbed during the period of growth of the tree.
4
The ash also contains heavy metals, causing an undesirable environmental effect, but the content of heavy metals is normally lower than in other solid fuels.
A special characteristic of ash is its heat conservation property. For wood stoves, the ash layer at the bottom of
the stove forms a heating surface, transferring heat to the final burnout of the char. For heating systems using a
grate, the ash content is important in order to protect the grate against heat from the flames.
Wood also contains salts that are of importance to the combustion process. It is primarily potassium (K) and
partly sodium (Na), based salts resulting in sticky ash, which may cause deposits in the boiler unit. The Na and K
contents in wood are normally so low that they will not cause problems with traditional heating technologies.
Wood and other types of biomass contain approx. 80% volatiles (in percentage of dry matter). This means that
the component part of wood will give up 80% of its weight in the form of gases, while the remaining part will be
turned into charcoal. This is one reason why a sack of charcoal seems light compared to the visual volume. The
charcoal has more or less kept the original volume of the green wood, but has lost 80% of its weight.
The high content of volatiles means that the combustion air should generally be introduced above the fuel bed
(secondary air), where the gases are burnt, and not under the fuel bed (primary air).
2.1.2 Straw
Straw is a somewhat challenging fuel for firing, as it has low bulk density and high chlorine and potassium content. Straw-fired boilers have had major operational problems because of rapid deposit formation and fouling/corrosion rates. Additionally, problems with composition and end use of mixed fly ash as well as deactivation of de-NOx catalysts have been reported. Nevertheless, straw has been used for energy production in some
countries to supply heat in small-scale applications and recently also in larger-scale combined heat and power
production applications as a primary or secondary fuel.
However, these boilers, which are based on grate combustion if only straw is fired and fluidised bed or pulverised combustion if straw is co-fired with coal, are usually designed for burning straw either as a main fuel or
secondary fuel together with coal. This means that boiler live steam parameters are usually clearly lower than
those in large peat- and coal-fired condensing power plants in order to avoid risks related to corrosion, fouling,
deposit formation and bed sintering.
The net calorific value of straw is typically about 17 MJ/kg (dm), moisture content 17-25 and ash content in dry
matter about 5%. The bulk density of “loose” straw is 50-70 kg / m3, which is a challenge for good operation of
the fuel feeding system.
The incineration of fresh straw is to be avoided because of corrosion risk caused by high alkaline metal content.
Dry straw is a safe and well-known fuel.
2.1.3 Spent mushroom compost
Mushroom compost is produced by composting chopped straw and poultry manure with the addition of water
and gypsum. After composting, the compost is pasteurised and finally mushroom spawn (seed) is added.
The compost is supplied to the mushroom grower usually in plastic bags, blocks or as bulk compost. These are
placed out in insulated polythene tunnels. When the mushroom mycelium has grown through the compost, a 5
cm deep layer of limed peat is placed on top. This casing layer induces the formation of fruiting bodies or mushrooms. About a week later, harvesting of the mushrooms commences and this continues for four to six weeks.
After cropping, the spent mushroom compost (SMC) is removed to make way for the next crop. The main constituents and their compositions in mushroom compost are typically straw (39%), poultry litter (29%), water
(29%), gypsum (3%) and peat. The variation of the constituents can be wide and e.g. chicken litter is sometimes
replaced with horse manure.
5
The fuel properties of SMC are not known. In addition the variation in the physical and chemical properties
added to the very low calorific value (only about 2.5 MJ/kg as received) due to high moisture (68% in dm) and
ash (35% in dm) content means that SMC is clearly a very low value waste product that is not suitable for power
generation in the condensing power plans under review in this study. Moreover, there are obviously no experiences in using SMC as fuel in large power generation applications.
2.1.4 Chicken litter
Chicken litter has been used in numerous countries mainly in heat production. There are also a couple of commercial-scale power plants, e.g., in the UK where chicken litter is fired as a main fuel or secondary fuel to produce electricity. However, many of these power plants are suffering constantly energy production interrupts
due to difficulties related to “difficult” fuel even though they have been specially designed to be able to burn
chicken litter.
The main problem has been very aggressive and sticky fly ash dust, which has blocked flue gas paths between
the heating surface tubes of the boiler, in particular in cold areas in the economizer and air preheater. As a consequence, the boiler must have been shut down and cleaned many times a year.
The net calorific value of chicken litter is typically about 15 MJ/kg (dm), moisture content about 35% and ash
content in dry matter about 7%. The bulk density of chicken litter is about 400 kg/loose-m3.
2.2
Fuel handling and pre-treatment
Each combustion method needs specific handling and feeding operations and therefore it is impossible to give
detailed overall design basics for handling and feeding operations. However, there are some common features
specific to biomass properties.
The handling and flow properties of biomass are usually poor because of particle size variation and high fibre
and oversized particle content. Additionally, the bulk is adherent, corrosive and even abrasive. The weak flow
properties imply high internal and external friction. Of course, there are exceptions like pelletised fuels made
from dry raw material.
Basically the handling and conveying system should be designed according to the fuel properties. Because of
the obscure dimensioning parameters and the fact that several fuel types have to be fed into the boiler either
through the same or separate lines depending on the case, the investments become rather expensive and the
systems complicated.
2.2.1 Fuel receiving and sampling
Solid biomass is delivered normally by trucks or truck containers. In most cases the fuel supplier is responsible
for delivery and unloading. The high shear strength and low energy density of biomass has led to the design of
receiving pits and pre-screens that are as open as possible, enabling sufficient unloading for the boiler capacity.
Usually different fuel fractions will be blended during transportation and in the receiving station. There are very
few separate units for mixing. In large plants, fuels are also blended sufficiently in handling and conveying, especially in the loading and unloading of silos.
Manual fuel sampling is common if many fuel types are used and if there are several suppliers but also automatic sampling has been developed.
2.2.2 Fuel screening
The high shear strength and fibre content emphasise the design of screening. One of the best screening devices
is a disc screen where the critical factors are the feeding, screen aperture dimensions, disc shape and rotation
velocity when optimising the proportion of acceptable fuel from over-sized reject material. The normal metal
separation based on ferromagnetic character is sufficient if the proportion of demolition wood is not extensive.
6
In some cases where the fuel flow has increased, the capacity of magnetic separation has been adjusted accordingly.
2.2.3 Fuel conveying and storing
The transport capacity of conveyors and reclaimers is very important when fuel quality reduces. The handling of
more fibrous materials has affected the design of crossing points, chutes and openings and especially silos and
stores. The principal design methods are not as valid as practical experience and feedback from plant operators.
The store sizes (of intermediate storages) have grown larger due to lower calorific values. At the moment the
largest round-bottom intermediate store equipped with a slewing screw reclaimer is about 5,000 m3. On the
other hand, the volume of a single A-shape store can exceed 20,000 m3. Present stores are often provided with
flow distributors, which prevent segregation and direct flow.
2.2.4 Fuel feeding into the boiler
The most reliable boiler hopper or silo has been proved to be a cylindrical silo equipped with an unloading
screw turning on the bottom. This structure also ensures the most accurate and adjustable discharge of fuel.
Fuel will be unloaded mostly on chain conveyors on both sides of the boiler. The mass flow rate is measured
from conveyors but the primary information for fuel feeding control comes from steam pressure and combustion chamber measurements, which provide faster response for adjustments. Most electric motors have variable
speed control. This is done with frequency converters, which can be controlled externally or locally, for example,
by rotation speed, level, space, position, and torque using modern control methods.
2.2.5 Control, fire and occupational safety
Control, fire and occupational safety are based on a modern distributed control (DCS) system. A lot of research
has been done to study fuel safety properties. Experience has shown that the most critical parts of the process
are the receiving, screening, crushing and feeding line near the boiler. The use of modern monitoring (also
cameras utilising broader wavelengths), detection and preventive technology has significantly increased.
2.3 Types of co-firing applications
There are basically three options for co-firing: direct, indirect and parallel co-firing. Direct co-firing is combustion of biomass together with fossil fuel in a single combustion chamber. Indirect co-firing means combustion
of fossil fuel with previously gasified biomass, and parallel combustion requires at least two boilers as biomass is
burned in one and fossil fuel in another.
2.3.1 Fluidised bed combustion
Fluidised bed technology is the most flexible for burning different types of fuel. With careful planning and testing, boilers designed for multi-fuel use may accept new fuels without any problems. Fluidised bed boilers designed for coal combustion can also be converted to biomass/coal co-firing with a relatively small investment.
A fluidised bed is a bed of solid particles suspended or fluidised by forcing air through the bed. When the air
velocity is increased above the minimum fluidisation velocity, air flows through the bed as bubbles. This type of
bed is called bubbling fluidised bed (BFB). When the air velocity is increased, the particles are carried higher up
in the reactor. With a circulating fluidised bed (CFB) it is no longer possible to distinguish between the bed and
freeboard area. A large fraction of the particles rise up from the bed and are circulated with the help of a cyclone back to the bed. The circulating bed material can be used for temperature control in the boiler. Fluidisation velocity of a bubbling fluidised bed boiler is typically between 1 and 3.5 m/s, whereas in a circulating fluidised bed boiler it is 3-6 m/s.
Fluidised bed boilers can be designed to combust almost any solid, semi-solid, or liquid fuel as long as the calorific value is sufficient to heat the fuel, drive off the moisture and preheat the combustion air. They achieve high
7
fuel-to-steam efficiency, typically over 90%, even with challenging, low-grade fuels. Because of the high amount
of hot circulating bed material, it is possible to burn moist, heterogeneous fuels with low calorific value. With
high moisture content fuels, a support fuel can be used. More than 90% of the bed is sand or ash and the rest is
fuel. This balances changes in fuel quality and moisture and prevents combustion disturbances and undesired
variation of bed temperature. In some cases, special bed materials can be used in order to avoid bed agglomeration.
Coal contains a large portion of fixed carbon, which burns in the bed, and the freeboard or riser temperature is
clearly lower than the bed temperature. With a higher amount of wood, the freeboard temperature increases.
Wood contains large amounts of volatile matter, which burns mostly in the freeboard area, thus causing the
temperature to rise.
The choice between BFB and CFB technology has been largely linked to the choice of fuels. As a simpler and
cheaper technology, BFB has been favoured in plants fuelled exclusively with biomass or similar low-grade fuels
containing highly volatile substances. The new enhanced CFB designs can be a competitive alternative even in
smaller biomass-fired plants.
At the moment, fluidised bed combustors are the best combustion systems thanks to their ability to burn a
wide assortment of fuels and still keep emissions low. The temperature in a fluidised bed is lower than in pulverised fuel combustion, and efficient combustion is achieved by a relatively long residence time in the bed. Because of the relatively low combustion temperature in a circulating fluidised bed (typically around 850 °C),
thermal NOx formation is not a problem.
Figure 5. Bubbling fluidised bed combustion, Foster Wheeler
8
Figure 6. Circulating fluidised bed combustion, Kvaerner Power
2.3.2 Pulverised combustion
The main motive to use biomass in coal-fired pulverised fuel boilers is the need to reduce emissions and to exploit available local biomass resources. Using biomass in existing pulverised fuel boilers can be more profitable
than building a new biomass plant using 100% biomass. On the other hand, the amount of available biomass
may be a restricting factor. The American experiences of biomass and coal co-firing are mostly based on pulverised fuel combustion in coal-fired boilers.
Different options in using solid biomass in a pulverised fuel boiler are described as follows. There are basically
three options for direct combustion in a pulverised fuel boiler.
1
When the proportion of biomass is rather low, it can be fed together with coal to mills and then be burned
together with coal through coal burners. In principle, this is the simplest option and involves the smallest
investments. On the other hand, this technology also carries the highest risk of malfunction of fuel feeding
systems.
2
The second option involves separate handling, metering and grinding of the biomass and injection into the
pulverised fuel upstream of the burners or at the burners. This option requires the installation of a number
of biomass transport pipes across the boiler front, which may already be congested. It may also prove to be
more difficult to control and to maintain the burner operating characteristics over the normal boiler load
curve.
3
The third option involves the separate handling and grinding of the biomass with combustion through a
number of dedicated burners. This approach represents the highest capital cost option, but involves the
least risk to normal boiler operation.
The problem with all these is that the loss in power output is almost inevitable and that the proportion of biomass in fuel blend is limited.
9
Figure 7. Pulverised coal-fired boiler
2.3.3
Grate combustion
Grate boilers have been traditionally used for solid fuel combustion. The size range is broad; grate boiler technology is available from 15 kW up to 150 MW. Grate boilers are suitable for many types of fuels: coal, wood fuels,
waste fuels, peat and even straw. Even fairly moist fuels can be used if this is taken into account in boiler design.
In comparison to fluidised bed combustion, boiler efficiency of a grate boiler is lower and flue gas emissions
higher. It is also more sensitive to changes in fuel quality and moisture, and automation of grate combustion is
difficult. However, the structure is simpler so the investment, operation and maintenance costs in most cases
are lower.
One of the problems related to grate firing is the melting. Temperatures in the combustion chamber may reach
1300-1400 °C. Ash melting problems may be reduced by using mechanical and water-cooled grates and by
avoiding the use of preheated combustion air in the final burning area.
The grate structure is selected according to the fuel properties. The most typical are: fixed flat grate, fixed sloping grate, mechanical sloping grate and chain grate. There are also special grate types for special fuels, such as
waste incineration grates or cigar combustion grates for straw. The key issues in grate firing are homogeneous
fuel particle size and quality, proper sizing of the combustion chamber and efficient mixing of the combustion
air.
10
Figure 8. Sloped grate furnace
2.3.4 Gasification
Gasification makes it possible to use biomass residues also in pulverised-coal-fired boilers. Indirect combustion
technology enables the utilisation of larger proportions of biomass in pulverised fuel boilers, gas boilers and gas
turbines. Instead of grinding, solid biomass is pre-processed in a gasification plant and the product gas is
burned in a boiler together with pulverised coal or natural gas, for example. Gasification technology is commercially available and there are many different types of gasification systems, atmospheric fluidised bed gasification being one of the most cited in recent literature.
A separate CFB gasifier connected into a coal-fired boiler has been shown below.
Figure 9. The biomass CFB gasifier with flue gas cleaning, Foster Wheeler
11
2.4 Operational experiences from existing co-firing power plants
2.4.1 Finnish case study on power plant availability
A recent study on the effects of wood fuels on power plant availability showed that the use of wood fuels actually involved more problems than expected. Twelve Finnish power plants with fluidised bed boilers, from 100 to
300 MWth, answered a questionnaire on power plant availability. All these plants have either increased the use
of wood fuels, or recently started it. The objective of the project was to determine critical properties of wood
fuels in respect of power plant operation, to determine the optimal conditions for reducing detriments, and to
study how storing and processing of wood fuels affect steam boiler operation.
More than half of the plants:
•
have had problems in the feed stock’s discharging gears, conveyors and feeding gears
•
had noticed bed-related problems during the use of wood fuels
•
had detected that wood fuels affect furnace temperatures
•
have had problems because of the variation in furnace temperature
•
had discovered that wood fuels contribute to deposit formation
•
had noticed that the quality of wood fuel fluctuates
•
had noted that wood fuels change the ash quality
•
said that the increased use of wood fuels had affected plant performance
On the other hand more than 80% of the plants:
•
can feed the fuel smoothly into the furnace
•
can spread the fuel evenly to different sides of the furnace and
•
said that the fuel spreading was not different when wood fuels were used
•
said that the use of wood fuels did not increase the need for soot blowing and
•
said that the increased use of wood fuels had affected to the plant emissions
2.4.2 Pulverised coal-fired boilers
In Central Europe one option to reduce CO2 emissions and to increase the share of renewables in energy production is to use biomass co-firing in large coal- and gas-fired power plants. Tests have been carried out in operating power plants in Germany, the Netherlands, France, Denmark and Spain, which are co-firing wood and
agro biomass in a pulverised coal-fired combustion. The example of the trial and continuous operation comes
from Germany.
2.4.2.1
Schwandorf
Supported by Bavarian State Government the biomass co-firing was tested at the power plant Schwandorf of
Bayernwerk AG. The series of tests comprised four 24-hour tests and one long-term test. The tests with the cofiring of straw and other culmiferous materialswere realized in unit B (280 MWth) in 1996. Because of good results of the co-firing test Bayernwerk obtained a permission to burn waste wood by co-firing. After the shutdown of units B and C waste wood has been co-fired in unit D since 15 June 1999.
The conditions for the test were the following: the biomass utilised was brick-shaped (biomass pellets) and the
heating value was similar to the Czech hard brown coal which fuels the plant; no change of the existing plant
technology was made (no investment); handling of biomass caused additional expenditure and they were
minimised in large-scale tests; no exceeding of licensed limits for flue gas and residuals.
12
The goals of the tests were to evaluate biomass unloading, transport, mixing and grinding ability and combustion characteristics, and the influence of various biomass fractions. The limits of biomass share due to the plant
or process technology were also determined and influence of biomass co-firing on the emissions and residuals.
The operational influence on the deNOx plant and deSOx plant and signs of corrosion were studied as well.
The co-firing tests were carried out as follows:
•
unit B, test with a homogenous mixture of biomass and brown coal; mixing by a wheel loader and in a conveying system; mixture goes to two of four coal mills; there the material is ground and blown into the boiler
•
four measurements of 24 h in 1995 and a continuous operation for about five days
•
first measurement: 80 t straw pellets corresponding to 5% of the heat value of brown coal
•
second measurement: 320 t straw pellets corresponding to 20% of the heat value of brown coal
•
third measurement: 160 t cereals = 10% of heat value
•
fourth measurement: 160 t grasses from landscape care = 10%
•
continuous test for about one week in 1996 with 1,600 t straw pellets and 5,300 t brown coal (corresponding 20%)
•
after that cooling down of the whole plant and inspection of each part of the plant (fuel mills, burner of
pulverised fuel, boiler, heating surfaces, flue gas cleaning plant and ash delivery)
Handling experiences:
Biomass pellets:
•
tipping and loading of biomass pellets cause great dust emissions; partly poor visibility
•
less mechanically stable pellets are not usable for co-firing
Waste wood:
•
only few dust emissions occurred, damping the wagons during loading reduces all dust emissions
The mechanically unstable pellets from the forage drying plant caused problems with dust emissions so that
they are not suitable for long-term operation regarding the internal handling of the power plant. If long-term
biomass co-firing is to be executed without investments, additional plant technique for handling mechanically
stable pellets with low fine particle contents is necessary.
The currently used waste wood causes very low dust emissions compared with the biomass pellets. However, to
minimise the dusting further a premixing of biomass and brown coal at the coal storage place and dumping
during the loading into the wagons is performed.
The existing mills in unit B are rigid-hammer crushers with gravity separation (hammer mill crusher with metal
crusher teeth, supplier Babcock DSG 90). The mills were operated with biomass shares of between 10% and
40%. Shares of over 30 to 40% cannot be handled by the existing grinding system. When the biomass use was
10% maximum, no problems in co-firing were detected.
The pellets had small sizes as described above and the waste wood was also cut to wood particles with sizes of a
few centimetres before delivery. The fuel passed from the boiler bunker into the coal mills and was ground to
dust.
2.4.3 Grate boilers
The traditional method to use wood fuels is the combustion on a grate. This study includes a boiler equipped
with a rotating grate in small-scale CHP production. When using a rotating grate the screw conveyor pushes the
fuel from the lower zone onto the grate of the primary combustion chamber. The rotating grate moves the fuel
13
bed cyclically by four hydraulic devices. The movement of the grate is adjusted in such a way that the fuel is
distributed as an even bed over the whole grate. The fuel dries and ignites on the grate (see Figure 10).
Figure 10. Rotating grate (Wärtsilä Biopower)
2.4.3.1 Iisalmen Sahat – IPO WOOD
Iisalmen Sahat Oy - IPO WOOD, is a private sawmill, established in 1922. It owns operating mills both in the
town of Iisalmi (Peltosalmi Sawmill) and Kiuruvesi (Kiuruvesi Timber) in Central Finland. Iisalmen Sahat Oy burns
all by-products of its sawmills - bark and sawdust - in its own biofuel-fired boilers.
Sermet Oy (now owned by Wärtsilä Biopower) has delivered both rotating grate boilers to the company in Kiuruvesi: 3.5 MW rotating grate (BioGrate) in 1994, and 8 MW rotating grate (BioPower) in 1999. The latest delivery
also included integrated small-scale electricity production (CHP plant). The -BioGrate combustion technique
applied at the plants is designed for moist fuels.
Kiuruvesi Timber generates approx. 151.2 TJ heat. More than 90% of heat is sold to Savon Voima Oy, which is
responsible for district heating service for the town of Kiuruvesi. The design electricity production of the new
CHP plant is approx. 5 GWh. As the total auxiliary electricity consumption of Kiuruvesi Timber Oy is 3.7 GWh,
part of electric power can be transmitted for the Peltosalmi sawmill’s own consumption. All heating and power
plants of IPO WOOD are operated unmanned and monitored from one sawmill control room. Four employees
operate the plants.
The fuel mixture is forwarded with the bucket loader from the field storage to the fuel storeroom of the plant.
This storeroom is a rectangular concrete-cast building, partly built under the ground level. Its nominal capacity
is 400 m3, and hence it must be filled at least once a day. The upper part of one wall is open over the whole
length, and the storeroom is fed through this opening. It is not possible to feed fuel directly from the lorry into
the storeroom.
The storeroom is discharged with a moving bar unloader. There are six parallel dischargers in two groups of
three dischargers, each group having its own hydraulic equipment. This ensures the fuel feed into the boiler
although one of the units were broken or under service.
A steel plate has been installed on the bottom of the storeroom, as the concrete bottom is susceptible to wear.
At the older plant, the guide bars of the dischargers were encased afterwards, as the fuel intruded under the
guide bars distorted the bars upwards.
14
Homogeneous fuel feed onto the scraper conveyor in the boiler room is ensured with a shredder roll at the discharge site. The roll homogenises the fuel, and also breaks possible lumps and in part frozen material among
the fuel.
There is no screen, crusher or magnetic separator in the fuel handling system. Possible large wood pieces and
other impurities like stones and metals are removed during mixing and filling of the fuel. These do not often
cause problems in the operation of the plant. The feed screw crushes part of wood pieces. Sometimes rather
large metal pieces have been carried through the whole handling and combustion line and found in ash.
The two boilers of Kiuruvesi Timber Oy burn 53 000 bulk-m3 of sawdust and 35 000 bulk-m3 of bark a year. The
by-products of Kiuruvesi’s own sawmills are not sufficient, but additional fuels must be bought in the wintertime. Biowatti Oy supplies some thousands cubic meters of bark and sawdust. In 1999, about 1 500 bulk-m3 of
forest residue chips were also burned, and the share of forest chips is expected to increase in the future. In addition, about 2000 bulk-m3 of drier industrial chips are annually mixed among moist fuels. The moisture content
of sawmill by-products ranges from 50% to 65%, depending on the season. The moisture content of forest residue chips also exceeds 50% during winter months.
Bark consists primarily of spruce bark. During the growing season, spruce bark is loosened as long strips in debarking. Hence, bark is crushed at sawmills immediately after debarking in the spring and summer to avoid
problems in fuel handling and feed. The maximum bark particle size of 100 - 200 mm does not cause problems
in the handling equipment.
2.4.3.2 Heizkraftwerk Würzburg
This study presents one almost “traditional” method of co-firing wood with coal on a grate. The example comes
from Heizkraftwerk Würzburg, Germany.
There are altogether three boilers at the power plant. The main fuel (design fuel) is coal with a sulphur content
of < 1% and a calorific value of 32 MJ/kg (size 8-20 mm). In 1998 143 000 tonnes of coal were used (100 000 to
140 000 t/a). During six weeks a maximum 25% share of untreated wood was used in boiler 2 for co-firing. Wood
chips from untreated wood with a calorific value of 15 MJ/kg, a size of 10-50 mm, were used for co-firing.
Coal is delivered to the harbour, in addition to the coal storage place of the Heizkraftwerk Würzburg (max. load
of coal storage place 8,000 tonnes). Ship unloading is carried out by crane to the coal storage place and distributed on the coal storage place with funnel cars and belt conveyors. A belt conveyor fills the underground bunker. Coal is taken from the underground bunker to a dump car (so-called: frog) by a bucket elevator; if the
bucket elevator breaks down, an emergency coal-handling scraper feeds the boiler with fuel. A dump car (frog)
distributes the coal to different daily-filled boiler bunkers (6 silos).
Wood chips are transported by lorry. Lorries unload directly into the underground bunker (also usual for coal if
coal is delivered by truck). Transportation is similar to that of coal; by bucket elevator into the dump car (frog)
and then into another daily-filled boiler bunker.
The fuel from the coal bunker and the wood bunker arrives at two balance belt conveyors which control the fuel
feeding by constant weighing; the fuel falls into a coal funnel. From the funnel the fuel mixture arrives at a coal
chute and from there it goes to the firing grate of the boiler (max. load of the boiler 11 t/h). All fuels (coal and
wood) are delivered in fixed qualities and sizes so that no additional preparations are required. Wood chips
which are too large cause problems at the dosage (clogging).
2.4.4 Fluidised bed boilers
2.4.4.1 Rauhalahti
The bubbling fluidised bed (BFB) boiler (300 MWth) under review in this study is located at the Rauhalahti municipal CHP plant in Finland. A heat production company Jyväskylän Energiantuotanto Oy, owned by Fortum
15
Heat and Power (60%) and the City of Jyväskylä (40%), owns a total of 29 different boiler types. Two of these are
power plant boilers (the boilers of Rauhalahti and Savela).
The main boiler of the Rauhalahti plant was commissioned by Tampella Power (present Kvaerner Pulping Power
Boilers) in 1986. This pulverised-fired boiler was converted into a fluidised-bed one in 1993. The boiler generates back- pressure district heat for the City of Jyväskylä and its surroundings and steam for Metsä-Serla Kangas
Paper Mill and electricity for the grid.
The fuels (Table 12) of the main boiler are milled peat, wood fuels (sawdust, bark, cutter dust, wood chips) and
coal. Oil is also used to some extent. The modification of the boiler made burning of wood fuels possible. At
present, about 30% of the fuel flow is wood. In addition, burning of small amounts of crushed recycled fuel
(REF) with wood has been tested.
Table 12. Consumption of fuels at the Rauhalahti CHP plant (TJ) from 1994 to 1999
At the Rauhalahti CHP plant fuels are handled as follows: Rear-unloading trailer lorries bring fuel to the receiving station (design capacity of fuel flow is 80 t/h). There are two lines at the unloading station, one mainly for
wood fuel (sawdust/ bark) and the other line for milled peat. Coal is carried by train to the coal yard of the
power plant and forwarded by a wheeled loader to the process when needed.
At the receiving station, the fuel is pre-screened with disc screens. The screenings are disposed of at the yard for
crushing with a mobile unit operated by contractors. The pre-screened fuel is conveyed with belt conveyors to a
separate screening building equipped with a disc screen and a crusher. The screened peat/wood and crushed
screenings are conveyed with an ascending conveyor into round-bottom intermediate storage, which is discharged with a screw unloader. From this storage the fuel is lifted with belts to two feeding bins. One feeding
bin is discharged with an apron conveyor and the other with a screw unloader to a belt conveyor and further to
a scraper conveyor. From there the fuel falls to a rotary air-lock feeder and flows forward via feeding tubes to
three sites on both sides of the boiler.
The handling and feeding lines are designed for peat fuels. This has emphasised the importance of fuel quality
control and the effective mixing of different fuels. The fuel homogenisation takes place in the delivery and/or at
the receiving station. At the moment there are also plans to construct a separate feeding line for the new wood
fuels. There have been difficulties with handling and feeding, which are mainly caused by the change of fuel
variety, but the overall usability and operation time of the plant have been very high (table 13).
Table 13. Operating time and availability in 1994-1998 at the Rauhalahti CHP plant
16
Kone/Roxon Oy delivered the outdoor conveyors and BMH Wood Technology the indoor conveyors. The indoor
conveyors were renovated during the boiler change in 1993. These were included in the delivery of Tampella
Power Oy (present Kvaerner Power) (subcontractor was BMH).
2.4.5 Gasification
2.4.5.1 Lahti
Lahden Lämpövoima Oy is owned by Lahti Energia Oy, which is a municipal company. The aim of the company
is to provide heat and electricity (CHP plant) for the Lahti area. It can also be used as a peak reserve power station for electricity. Originally the power station burnt heavy fuel oil and it was brought into commercial operation in 1976. The boiler was also converted to coal in 1982. When the natural gas network was extended to the
city of Lahti, a gas turbine and recovery boiler plant was next to the existing power station and supplement gas
burners were installed in the main boiler in 1986.
The steam boiler’s thermal effect is 350 MW. The total plant’s electricity capacity is 185 MWe in back pressure
operation and the district heat capacity 250 MWth. The net efficiency of the power station can reach 85%.
Increasing fuel costs, environmental demands and increasing energy consumption pushed the company further
to look for new solutions to energy production. Different solutions were considered, such as BFB retrofit, separate front FB burner and gasifier. The gasifier alternative was selected because of the modern technology and
emission control. The support of the EU THERMIE programme for the new technology helped the selection.
The aim of the Lahden Lämpövoima Oy`s Kymijärvi Power Plant gasification project is to demonstrate on a
commercial scale the direct gasification of wet biofuel and the use of hot, raw and very low calorific gas immediately in the existing coal-fired boiler. The gasifier replaces 15% of the fossil fuels and reduces SO2, NOx and CO2
emissions. The effect of the atmospheric CFB gasifier is 40–70 MWth depending on the moisture content and
heating values of the fuels. The fuels gasified are different types of biofuel and recycled fuel (REF) from sourceseparated waste.
The gasifier delivered by Foster Wheeler Energia Oy was commissioned at the beginning of 1998. Figure 11 presents schematically the process.
17
Figure 11. Lahden Lämpövoima Oy’s biofuel gasifier connected to a pulverised coal-fired boiler
Table 14 presents fuels used in the gasifier between 1998 and 2002 as fuel energy percentage. The table also
shows the total fuel utilisation of the whole plant (in kilo tonnes).
Fuel
Biomass
REF
Plastics
Railway sleepers
Shredded tires
Total
Unit
%
%
%
%
%
kton
1998
71
22
6
1
80
1999
63
23
13
1
106
2000
63
29
8
92
2001
62
26
12
116
2002
58
31
11
104
Table 14. Fuel utilised in the Lahti gasifier
By the end of 2002 the gasifier has been in operation for 27 000 hours and produced 1700 GWh energy. The
amount of gasified fuels has been almost 500 000 tonnes and the availability of the gasifier rather high 97.5%.
The operating experiences of the first operation periods have been good. Only a few problems occurred at the
gasification plant and the availability of the plant has been high since the beginning of operation. Most problems are related to the fuel processing and feeding. The best receiving and feeding system would be based on
three lines: untreated source-separated municipal waste (fuel fraction)/wood fuel/REF or plastic. It is estimated
that the additional cost of such a system would be around EUR 1 million. The system like that would also expand the fuel base of the gasifier.
As the gasifier and the overall co-firing concept have been proven to work technically very well, the system will
be in commercial use as long as the general surrounding conditions are favourable. In practice, the future of the
gasifier and the coal-fired boiler of Lahden Lämpövoima Oy depends strongly on the development of fuel, electricity and heat prices, taxes of fuels and the environmental legislation (emission limits).
18
2.5
Emissions to air
Co-firing of biomass with fossil fuels provides means to reduce SO2, and CO2 emissions and it may also reduce
NOx emissions. It is assumed that there is no net emission of CO2 from biomass combustion as plants use the
same amount of CO2 when they grow as is released in combustion.
The SO2 reduction is a result of both replacing a sulphur-bearing fuel with a sulphur-deficient fuel and a calcium-deficient fuel with a calcium-bearing fuel. Typical consequences of co-firing are modest reductions in
boiler efficiency, which limit the economic value of biomass fuels. NOx reduction is due to strengthening of reactions reducing NO in the furnace and/or lower nitrogen content in biomass.
Figure 12. Theoretical decrease in CO2 emissions by co-firing of wood with coal
2.5.1 CO2 emissions
Every tonne of biomass co-fired directly reduces fossil CO2 emissions by over a tonne. If the biomass were otherwise disposed of at a landfill without methane collection and flaring, the fossil CO2 emissions reduction could
be the equivalent of approximately three tonnes of fossil CO2 for every tonne of biomass burned.
2.5.2 SO2 emissions
By blending biomass with coal, SO2 emissions decrease because of the lower sulphur content of biomass. The
reduction can be even higher than this due to interaction of fuel constituents of different origin, i.e. biomass
and coal. The ash in biomass is often very high in calcium. Fuel-bound calcium compounds can work as sorbents as they can react with SO2 and SO3 to form calcium sulphate.
The efficiency of sulphur reduction in combustion processes depends on several variables such as
•
•
•
•
•
combustion temperature
excess of air
air staging
fly ash recirculation (in FBC)
fuel type
19
•
•
•
limestone characteristics
limestone and fuel feed distribution
Ca/S ratio.
It has been shown in laboratory-scale CFB combustion tests where coal and bark blends were burned that sulphur removal efficiencies from 15% (no bark) up to 80% (80% bark) can be achieved. In a large EU APAS project,
biomass/coal mixtures were burned in many different types of boiler (FBC and PC) from laboratory to full-scale
industrial boilers. Reductions of up to 75% were observed in SO2 emissions. This can be mainly attributed to the
low sulphur content of biomass, but increased sulphur retention in the ash was also detected.
2.5.3 NOx emissions
In chemical terms, nitrogen oxides should constitute all oxides of nitrogen (NxOy), including nitric oxide (NO),
nitrogen dioxide (NO2) and nitrous oxide (N2O). NOx is generally defined as the sum of NO and NO2. NO is the
main contributor of NOx in both pulverised fuel and fluidised bed combustion. In fluidised bed combustion, the
amount of NO (in NO + NO2) is 90-98 %. One nitrogen-containing compound that is often omitted in the context of greenhouse gas emissions is N2O.
Compared to pulverised fuel combustion, the lower combustion temperature in fluidised bed combustion provides an advantage in reducing the formation of thermal NOx. On the other hand, N2O emissions seem to be
higher in fluidised bed combustion. If lower NOx levels are required, adding ammonia or urea into the flue gas
stream can be done.
Research results on NOx formation in co-firing are somewhat contradictory. Some research groups claim that
NOx levels decrease when biomass is mixed with coal. Some results show just the opposite. NOx formation is a
very complex process. What is certain is that the combustion process is affected by a number of factors.
Because biomass has a high volatile and hydrogen content, it can be successfully applied in NOx reducing procedures such as air staging and re-burning. In contrast to the situation in pure coal flames, with coal/biomass
blends and air staging, low NOx emissions are attained already under fairly air-rich conditions. In re-burning,
biomass is superior to bituminous coal as a reducing fuel with regard to both emissions and burnout. Reduction
is based on reactions between hydrocarbon radicals and NO.
Because of the adverse effect of N2O on the atmosphere, a considerable amount of research has focused on N2O
formation/destruction mechanisms in fluidised bed combustion. N2O emission is strongly dependent on temperature and fuel composition. Contrary to NOx, N2O concentration in combustion gases decreases as the temperature rises. Adding biomass to the fuel mixture clearly decreases the N2O emission. A higher O/N ratio of
biomass has a positive impact on N2O emissions. The large amounts of calcium, potassium and sodium in biomass have a catalytic effect on N2O reduction. The effect of biomass on N2O reduction is more significant at
lower temperatures.
2.6
Boiler plant operation in co-firing
2.6.1 Blending of coal and biomass
Most challenges that co-firing poses to boiler operation originate from fuel properties. The differences in the
characteristics of coal and biomass can be summarized as follows:
•
Pyrolysis starts earlier for biomass fuels compared with coal fuels.
•
The volatile matter content of biomass is higher than that of coal.
•
The fractional heat contribution by volatile substances in biomass is approximately 70% compared with 3040% in coal.
•
The specific heating value of volatiles in kJ per kg is lower for biomass fuels than for coal fuel.
20
•
Biomass char has more oxygen compared with coal and it is more porous and reactive.
•
Biomass fuels have ash that is more alkaline in nature, which may aggravate the fouling problems.
•
Biomass fuels can be high in chlorine, but typically have low sulphur and ash content.
Figure 13. Results of traditional fuel analysis
Solid fuels contain carbon, hydrogen, oxygen, water, ash-forming elements, nitrogen and sulphur. Oxygen is
chemically bound in the fuel and the concentration is 45% of the weight in wood and 2% in anthracite coal on
dry ash-free basis. Fresh wood typically contains 50% of water by weight, whereas the moisture content for bituminous coals is approximately 5%. Wood-based fuels usually have low sulphur content but can have very
high chlorine content. In general, the structure and composition of coal differs greatly from those of biomass
fuels.
The aforementioned differences imply that if biomass fuels are blended with coal, the following implications
may be expected:
•
increased rate of deposit formation
•
shorter sootblowing interval
•
cleaning of heat transfer surfaces in overhauls may be required
•
higher risk of corrosion of heat transfer surfaces
•
bed material agglomeration (in fluidised beds)
•
higher in-house power consumption
•
higher flue gas temperature
The magnitude of these implications depends on the quality and percentage of biomass in the fuel blend. The
overall result is that operating and maintenance costs may increase, but this can be reduced or even avoided
with appropriate fuel blend control: the optimum percentage of biomass fuel in the fuel blend can be defined
with appropriate combustion tests accompanied with bed material and deposit quality assessments.
Wood-based fuels usually contain only a few per cent of ash, whereas coal typically contains 10 w-% or more.
Ash characteristics have an important role in boiler design because deposit formation, erosion and corrosion
should be minimised and defluidisation avoided.
21
2.6.2 Slagging and fouling
Slagging can be defined as the deposition of fly ash on the heat transfer surface and refractory in the furnace
volume primarily subjected to radiant heat transfer. Fouling is defined as deposition in the heat recovery section of the steam generator subject mainly to convective heat exchange by fly ash quenched to a temperature
below its melting point.
Substances that have vaporised in the combustion zone can condensate on the heat transfer surfaces by the
condensation of volatiles or the sulphating of SO3. These deposits may vary from light sintering to complete
fusion. The degree of fouling and slagging varies throughout the boiler depending on
•
local gas temperatures
•
tube temperatures
•
temperature differences
•
gas velocities
•
tube orientation
•
local heat flux on particles
•
fuel composition.
Figure 14. Schematic illustration of deposit formation and condensation of inorganic vapours on a
superheater tube surface
The existence of alkali metals in fuel ash is recognised to have an important role in deposit formation. In addition to the combustion conditions, deposit formation depends on the release and chemistry of chlorine, sulphur, aluminium silicates and alkalis during combustion.
The fireside behaviour of fuel impurities is a continuous source of slagging, fouling, or corrosion in one way or
another. Deteriorated heat transfer of the heat delivery surfaces result in lower combustion efficiency, and obviously corrosion in the fireside has far more serious consequences.
22
The main factors that contribute to fouling are caused by inorganic materials in the fuel. Biomass ash contains a
larger amount of alkalines compared with coal ash. This is particularly true for some agricultural residues and
new tree growth. The chemical composition of ash, such as alkali metal, phosphorous, chlorine, silicon, aluminium and calcium content, as well as the chemical composition of the compounds, affect ash melting behaviour.
Alkaline metals compounds are easily vaporised during combustion. In biomass fuels, a major proportion of
inorganic material is in the form of salts or bound in the organic matter, but for example in coal, a large proportion of inorganic substances are bound in silicates, which are more stable.
Additionally, chlorine-rich deposits induce hot corrosion of heat transfer surfaces. Although slagging and fouling may be detected quite quickly, corrosion progresses slowly over a longer period and may also occur without
any associated slagging or fouling. However, reliable measurements can be made about the corrosion risk of a
particular fuel blend in short-term tests where exposure times in the order of hours are applied.
Ash characteristics have an important role also in boiler design, because deposit formation, erosion, corrosion
and defluidisation of the bed sand should be minimised. Ash-forming matter in biomass fuels can be present in
several forms: as soluble ions, associated to organic matter or as minerals. The form in which the ash-forming
matter is present affects the behaviour of a fuel. There are significant differences in how ash- forming elements
are distributed in different fuels. In older fuels, ash-forming elements are present as minerals. In relatively young
fuels, up to half of the ash-forming elements can be organically associated or present as easily soluble salts or as
minerals.
According to present knowledge, control of the rate of deposit formation in biomass combustion is associated
with the reactions between compound that contain chlorine, sulphur, aluminium and alkaline substances. Highrisk chlorine compounds are of the type NaCl or KCl. These alkaline chlorides can, however, react with sulphur
and aluminium silicate compounds releasing HCl according to the following chemical reactions:
2KCl + SO2 + 1/2O2 + H2O --->K2SO4 + 2HCl
Al2O3 • 2SiO2 + 2KCl + H2O ---> K2O • Al2O3 • 2SiO2 + 2HCl
The S/Cl ratio in the feedstock has often been shown to affect Cl deposition and corrosion. In addition to aluminium silicate reactions, one parameter that has been often referred to is the sulphur-to-chlorine atomic ratio
(S/Cl) in fuels or fuel blends. It has been suggested that if the S/Cl ratio of fuel is less than two, there is a high risk
of superheater corrosion. When the ratio is at least four, the blend could be regarded as non-corrosive. According to recent studies AlSi/Cl ratio can even dominate over the S/Cl ratio.
2.6.3 Challenges and restrictive factors
The advantages of co-firing mainly relate to environmental benefits. Boiler and combustion process control,
however, becomes more challenging when biomass-containing fuel blends are introduced into the process.
Variations in the physical and chemical properties of wood-based fuels may cause unexpected problems
throughout the whole power production chain which in turn poses new challenges for fuel handling systems,
boiler design and combustion technologies.
If biomass is blended with coal, the maximum safe amount of biomass varies from case to case depending on
fuel properties. As coal-fired pulverised fuel boilers were originally designed for burning pulverised coal, the
following assessments should be carried out before starting to use biomass:
•
Particle size of biomass shall be small enough to ensure long enough residence time of biomass particles in
the furnace for burning out. Are coal mills capable of grinding biomass effectively enough?
•
How is the fuel fed into the boiler and is there a need for a new burner configuration?
•
What effects does co-firing have on the chemical composition and quantity of flue gases? The moisture
content of biomass is higher than in coal, so the flue gas composition will change and the volume will increase. The capacity of flue gas blowers may have to be revised.
23
•
How does co-firing affect boiler operation and temperature profiles within the furnace? The amount of
volatiles in biomass is higher compared with coal. This affects flue gas temperatures.
•
What is the effect on the desulphurisation system? Alkali metals in wood ash work as absorbents. The increased flue gas volume may also affect the functioning of the desulphurisation system.
•
What effects does co-firing have on possible NOx reduction equipment (catalyst poisoning of SCR system)?
•
What is the effect on electrostatic precipitators or other types of flue gas filter? The fly ash composition and
mass flow rate will change.
•
Changes in fly ash quality and volume? How does co-firing change ash end utilisation possibilities?
Depending on the chosen fuel feeding system, some changes have to be made to burners, fuel processing and
feeding systems, boiler automation and other boiler plant auxiliary equipment.
2.6.4 Advantages
In an optimal situation, co-firing of biomass with fossil fuels derives advantage from both fuel types and also
provides some “extra” advantages. These could be for example the reactions between different chemical elements originating from biomass and fossil fuel. These interesting reactions include the reactions between sulphur and aluminium silicates in the fossil fuel and alkalies in biomass ash. Alkalies work in the same way as limestone, or dolomite absorbing the sulphur, resulting in lower sulphur dioxide emissions in the flue gas.
Another example of mutual interests is the chlorine-binding capacity of fossil fuels. The sulphur level of biomass
is generally quite low. In some cases, the chlorine content of a biomass may be quite high, which means there is
a higher risk of corrosion in the boiler.
Another benefit of co-firing is the better use of local energy sources, decreased demand for waste disposal and
landfilling, more effective use of resources and saving of fossil fuel reserves. However, improper choices of fuels,
boiler design, or operating conditions could minimise or even negate many of the advantages of co-firing, and
in some cases may even lead to damage to the equipment.
2.6.5 Large-scale power production
With regard to biomass, co-firing in large plants creates a potential for high electric efficiencies due to high
steam parameters and technical measures for efficiency improvement. Therefore co-firing in large thermal
power plants can lead to an overall saving of fuels in comparison to independent fossil and biomass plants.
The possibility to co-fire biomass in coal-fired boilers offers a huge potential at European level as well as worldwide. It is probably one of the most realistic ways of achieving the objective of doubling the share of renewable
energy sources in the EU energy balance.
Co-firing is already commonly used in the USA, Finland, Denmark, Germany, Austria, Spain, Sweden and many
other countries. The production capacity of a co-firing plant is typically 50 to 700 MWe, and there are also a few
units between 5 and 50 MWe.
The most common technology is pulverised fuel combustion. The most suitable technology, however, is fluidised bed combustion, at least if the amount of biomass in the fuel flow is high and especially when the moisture
content of the biomass is high.
The suitable commercial technology is already available for new co-firing plants, but the real challenge is to
develop suitable technologies for retrofits in existing plants. Fuel flexibility, i.e. combustion of fuels with varying
relative amounts of coal and biomass, pose new challenges for plant operators. Especially understanding the
deposition formation and behaviour is a key issue in optimising plant operation and in securing plant performance and high availability.
24
2.7
Ongoing research and development within the EU
The development of renewable energy - particularly energy from wind, water, solar power and biomass - is a
central aim of the European Commission’s energy policy. There are several reasons for this:
•
Renewable energy has an important role to play in reducing carbon dioxide (CO2) emissions - a major
Community objective.
•
Increasing the share of renewable energy in the energy balance enhances sustainability. It also helps to
improve the security of energy supply by reducing the Community’s growing dependence on imported
energy sources.
•
Renewable energy sources are expected to be economically competitive with conventional energy sources
in the medium to long term.
•
Renewable energy is, by definition, local energy. Its development can create new business, bring employment and encourage economic and social cohesion in regions that otherwise lack industrial development.
•
There is a considerable export potential for renewable energy technologies, particularly in the developing
world.
ALTENER, the only Community programme to focus exclusively on the promotion of renewable energy sources,
ended its five-year term at the end of 1997. It has now been succeeded by ALTENER II, an initiative that will extend activities in the renewable energies field and make a major contribution to the Community Strategy and
Action Plan outlined in the White Paper ‘Energy for the Future: Renewable Sources of Energy’.
The need for Community support for renewable energy is clear. While several of the technologies, notably wind
energy, small-scale hydro power and energy from biomass, are economically viable and competitive, and others
are approaching viability, initial investment costs are high and investors often lack confidence in technologies
that are relatively unknown. As a result, development has been limited, and the sector needs help if it is to ‘take
off ’ in marketing terms.
2.8
Summary and conclusions
Co-firing is often the first and most economical step and way to increase the utilisation of biomass fuels in all
circumstances.
Co-firing is used for the following, specific reasons:
•
In the Nordic countries the forest industry is harvesting wood raw material for production of pulp or timber.
Wood residues from debarking and other wood processing are already available in the plant in the costeffective way.
•
New environmental regulations and taxation of fossil fuels have recently further increased interest in the
use of biomass and wood residues in energy generation.
•
European countries, especially the Nordic countries, have developed technology for the biomass utilisation
chain: wood raw material and wood fuel production, fuel handling, combustion and gasification technology, etc.
•
In co-firing even small amounts of biomass could substitute fossil fuels. The best case is if the boiler is already designed or retrofitted for co-firing. An alternative solution could be a biomass-fuelled gasifier connected to the existing coal-fired boiler.
The main problems in co-firing and gasification are the following:
•
Handling and feeding are problematic. Mostly combustion technology functions properly, but it is difficult
to homogenise fuels before combustion.
25
•
Mixing of different fuels is difficult; properties of biomass are not homogenous and they can vary in a wide
range.
•
Fuel feed control and accurate measurements are difficult, because the energy density of biomass fuels
varies.
•
When using fuels with high alkali metal content, such as straw, energy crops like reed canary grass and forest residues with green material (needles), problems can occur in steam boilers if no sulphur-containing
fuel, e.g. coal or peat, is used.
•
The use of different biomass fuels with coal and waste needs more control and advanced handling technology in the plants.
Operational experiences and case studies show typical ways to apply biomass co-firing and also differences between various countries. The effect of the structure of energy production, demand and consumption on the
biomass co-firing can be clearly seen. New biomass fuels have penetrated into the market in most countries.
The main method to utilize these biomass fuels is co-firing.
In the Nordic countries the pulp and paper industry has very strong influence on the use of biomass energy and
co-firing. The large forest resources also mean that many sawmills use their by-products, such as bark and sawdust, for energy production. The lack of fossil fuels and the cold climate have emphasized the effective use of
the indigenous fuels, mostly based on biomass. The situation has also given an impetus to the development of
very sophisticated boiler technologies and CHP solutions, as well as the establishment of skilled equipment
manufacturers.
In Central Europe co-firing of biomass takes place with coal, and in smaller units mixing of different wood-based
materials and residues. There are very interesting co-firing solutions for large coal-fired boilers. In many cases
they are still trials, but many of these, for example, gasification technology will be continued and are being
commercialised. Also, the mixing of biomass with coal seems very interesting and tests should be extended.
In southern Europe co-firing mostly uses agro-biomass fuels in smaller units. There are also very specialized solutions for combustion.
At present, the main types of co-firing applications are:
•
•
•
•
fluidised bed combustion (CFB, BFB)
mixing of biomass with coal and combustion in a coal-fired boiler (pulverised combustion)
grate firing
separate gasification for biomass and the combustion of produced gas in a main boiler (usually coal-fired
boiler)
A summary of the properties of the main types of co-firing applications is shown in the following table:
26
Max amount of biomass, % of
thermal input
Biomass moisture content, %
Biomass particle size, mm
Applicability to agri-cultural biomass
Effect on SO2 emissions
Effect on NOx emissions
Ash handling
Effect on boiler plant availability
Direct co-firing in
fluidised bed boiler
Direct co-firing in
pulverised boiler
20-50
< 60
< 50
Restrictions
0-5 using mill
5-10 own feeding
< 40
< 5-10
Restrictions
Can be bigger than
amount of biomass
Reduces
Ashes mix
Can have negative effect
Equivalent to
amount of biomass
No essential effect
Ashes mix
Can have negative
effect
Table 15. Summary of the properties of the main types of co-firing applications
27
Gasification and gas burning in pulverised boiler (indirect co-firing)
10-20
< 55
< 50
Good
Equivalent to amount of
biomass
Can be used as reburn fuel
Biomass ash is separate
No effect
3 Theoretical and Technical Co-firing possibilities in
Ireland
3.1 Description of power plants under review
3.1.1 Moneypoint coal-fired power plant
General
Figure 15. Bird’s eye view of the Moneypoint coal-fired power plant
The Moneypoint pulverised coal fired condensing power plant is located near Kilrush in County Clare on the
estuary of the river Shannon on Atlantic coast. The plant consists of three identical units each of 305 MW gross
electrical output totalling 915 MW installed capacity. The pulverised coal boilers supply steam to the fourcylinder, single shaft condensing turbines. Steam is condensed using cooling water taken from the estuary. The
overall plant efficiency (net) is 37.5% and the net electrical output is 855 MW (285 MW each unit) as auxiliary
power consumption of the plant is 60 MW (20 MW each unit).
The first unit was put into service in September 1985, the second in June 1986, and the third in April 1987.
Equivalent running hours by the end of the year 2003 vary between 130,000 and 135,000 giving an average
running hours per year 7,600-7,800 depending on the unit. The availability of the plant has mainly been between 84% and 91% in the 1990´s.
The plant is owned and operated by ESB, which also purchases the power.
The basic data for one unit of the Moneypoint coal-fired power plant is shown in the following table and station
cross section in the following figure.
28
Fuel
Boiler type
Fuel input
Boiler efficiency
Gross power output
Net overall plant efficiency
Live steam parameters
Reheat steam parameters
Feed water
Flue gas end temperature and oxygen content
Average operating hours per annum (depending on the unit)
Cumulative operating hours since commissioning (depending on the unit)
Availability (for all three units)
Pulverised coal/HFO
Pulverised fuel boiler, natural circulation
with reheat
760 MW
93.5 %
305 MW (net 285 MW)
37.5 %
165 bar, 540 °C, 260 kg/s
40 bar, 540 °C, 235 kg/s
180 bar, 255 °C, 260 kg/s
145 °C and 3.6 % (dry)
7,600-7,800 h/a
130,000-135,000 h (since September 1985April 1987)
84-91 %
Table 16. Basic data for one unit of the Moneypoint coal-fired power plant
Figure 16. Cross section of the Moneypoint coal-fired power plant
29
Coal handling and storing
The Moneypoint power station is designed to burn a wide variety of internationally traded coals about 2.5 million tonnes per year. The price of coal supplied to the power plant is about 35 EUR/ton equivalent to about 5
EUR/MWh at present (2003) and subjected to an increase of about 6% by the year 2010. The following table
shows typical coal characteristics.
Carbon content (dry)
Hydrogen content (dry)
Nitrogen content (dry)
Sulphur content (dry)
Oxygen content (dry)
Ash content (dry)
Moisture content
Net Calorific Value
%
%
%
%
%
%
%
MJ/kg
73.4
4.6
1.6
0.6
8.1
11.7
9.7
25.3
Table 17. Typical coal characteristics
Coal is imported in large bulk carriers (50,000-180,000 tonne dead weight), which are discharged by two grab
type ship unloaders (capacity 40 tonne) on the deep water jetty (380 m long, water depth 25 m) at the station
site. Coal storage and handling facilities are designed for a total station capacity of 1200 MW including coal yard
stockpile capacity of 2,000,000 tonne.
Figure 15 (bird’s eye view) shows coal handling and storing equipment located at site area of the Moneypoint
power station.
Boiler technology
The boilers are pulverised coal fired, natural circulation drum boilers with single reheat, and they have 100%
HFO firing capability. Each boiler has 16 front wall fired low-NOx burners equipped with internal fuel staging, 4
tube/cylindrical ball type pulverisers (mills), 4 coal bunkers (600 tonnes each) and two 50% capacity designed
primary air, FD and ID fans. Fuel input of one boiler is about 760 MW and boiler efficiency 93.5%.
Coarse bottom ash is collected under the furnace in the ash hopper and conveyed to the ash disposal area (capacity 3,000,000 m3) located in the site area.
Flue gas emissions control
The original intervane burners have been replaced by low-NOx burners and overfire air (OFA) system a few years
ago in order to control NOx emissions. The NOx emission limit value is currently 1100 mg/Nm3 (at 6% O2, dry gas)
and measured emission values are typically around 900 mg/Nm3.
Because the NOx emission limit value will be 500 mg/Nm3 (at 6% O2, dry gas) at the beginning of the year 2008,
the Selective Catalytic Reduction (SCR) process has been selected as the optimum technology to reduce current
NOx emission level by about 50%. This process is based on ammonia injection located downstream of the boiler
economizer. The tender assessment is currently going on and an investment decision followed by a placement
of order is expected to take place by the middle of 2004.
At the moment, there is no desulphurization equipment for SO2 emissions removal from flue gases. The SO2
emission limit value is currently 3400 mg/Nm3 (at 6% O2, dry gas) subjected to 1800 mg/Nm3 for the year 2004
and 1400 mg/Nm3 for the years 2005-2007 as annual averages. Measured emission values are typically around
1400 mg/Nm3.
Because the SO2 emission limit value will be 400 mg/Nm3 at the beginning of the year 2008, a semi-dry flue gas
desulphurization (FGD) process has been selected as optimum technology to reduce current SO2 level by about
70%. This process is based on injection of water and hydrated lime into the absorber located downstream of the
existing electrostatic precipitator (ESP). As with the SCR process the tender assessment is currently going on
and an investment decision followed by a placement of order is expected to take place by the middle of 2004.
30
As part of the semi-dry FGD process a benign by-product is generated. When mixed with fly ash to stabilize the
by-product, this can be used in the construction of a landfill site within the power station. It can be marketed as
a light concrete, used as a fill material or landfilled.
Dust is removed by an existing ESP located downstream of each boiler. The dust emission limit value is currently
150 mg/Nm3 (at 6% O2, dry gas) and measured emission values are typically around 100 mg/Nm3.
Because the dust emission limit value will be 50 mg/Nm3 at the beginning of the year 2008, in addition to the
existing ESP, the bag filter installed downstream of the FGD equipment has been selected as the optimum
technology to reduce current dust level by about 50%.
Measured CO emission values are typically during normal operation (steady state combustions conditions)
about 35 mg/Nm3 (at 6% O2, dry gas).
The current flue gas emission control methods, measured emission values and emission limit values valid in the
year 2004 and 2008 are summarized in the following table.
Emission
Control method
NOx
SO2
Dust
CO
Low-NOx burners and OFA
ESP
Steady state combustion conditions
Unit (at 6% O2,
dry gas)
mg/Nm3
mg/Nm3
mg/Nm3
mg/Nm3
Measurement
result
900
1400
100
35
Limit value
(2004/2008)
1100/500
3400/400
150/50
-
Table 18. Summary of current flue gas emissions control methods and emission values
Fine fly ash is collected under the ESP in the ash hoppers and conveyed to the ash disposal area (capacity
3,000,000 m3) located in the site are
31
3.1.2 Edenderry peat-fired power plant
General
Figure 17. Photograph of the Edenderry peat-fired powered plant
The Edenderry peat-fired power plant is Ireland’s first independent power station located in Ballykilleen just
outside Edenderry in County Offaly. It is a condensing power plant with a net electrical output of 117.5 MW.
Auxiliary power consumption is 10.5 MW giving gross electrical output of 128 MW. The boiler is based on bubbling fluidised bed (BFB) technology and fuelled with milled peat with an input of 307 MW. The boiler supplies
steam (160/40 bar, 540/540 °C) to a two-cylinder reheating condensing steam turbine. Cooling towers are used
to condense steam after the turbine. The overall plant efficiency (net) is 38.4%.
The construction of the plant commenced in January 1999 and the plant was synchronized to the national grid
in September 2000. The plant has been in commercial operation since December 2000 for about 22,200 hours
by the end of the year 2003 giving an average running hour per year about 7,400. The availability of the plant
has been 87.4% in 2002 and 77.5% in 2003 including annual outage of 25 days.
The plant is owned and operated by Edenderry Power Ltd. The power purchaser is ESB under a 15-year agreement.
The basic data for the Edenderry peat-fired power plant is shown in the following table and the main process
diagram in the following figure.
32
Fuel
Boiler type
Fuel input
Boiler efficiency
Gross power output
Net overall plant efficiency
Live steam parameters
Reheat steam parameters
Feed water
Flue gas end temperature and oxygen content
Average operating hours per annum
Cumulative operating hours since commissioning
Availability
Milled peat
Bubbling fluidised bed boiler, natural circulation with reheat
307 MW
89.3 %
128 MW (net 117.5 MW)
38.4 %
160 bar, 540 °C, 100 kg/s
40 bar, 540 °C, 93 kg/s
175 bar, 250 °C, 100 kg/s
165 °C and 3.0 % (dry)
7,400 h/a
22,200 h (since December 2000)
78-87 %
Table 19. Basic data on the Edenderry peat-fired power plant
Figure 18. Main process diagram of the Edenderry peat-fired power plant
Peat handling and storing
The Edenderry plant has been built in the middle of a peat bog and it burns about 1 million tonnes of milled
peat per year with a 15-year agreement from Bord na Mona. The price of peat supplied to the power plant is
almost EUR 25/t equivalent to about EUR 11.3/MWh at present (2003) and subjected to an increase of about
12% by the year 2010. The following table shows typical peat characteristics.
33
Carbon content (dry)
Hydrogen content (dry)
Nitrogen content (dry)
Sulphur content (dry)
Oxygen content (dry)
Ash content (dry)
Moisture content
Net Calorific Value
%
%
%
%
%
%
%
MJ/kg
54.3
5.4
1.4
0.4
34.1
4.4
53.0
7.7
Table 20. Typical peat characteristics
The pre-crushed peat is supplied using a narrow gauge railway system and unloaded by a wagon tippler to a
receiving hopper (see Figure 19 for details). Railway wagon trains consisting of sixteen to twenty box type wagons, each wagon having a nominal capacity of 16 to 18 m3 will be drawn by a diesel locomotive to and from the
fuel off-loading facilities. It is also possible to supply peat by lorry, which are unloaded to the receiving hopper.
The lorries currently used vary in size; the smallest has a capacity of 80 m3 while the largest has a capacity of 100
m3. However, so far all peat has been delivered by rail wagons. It is anticipated that no peat will be delivered by
lorry in future either.
Figure 19. Delivery method for peat
Magnetic separators remove metals and screens coarse particles before peat is conveyed to the covered intermediate storage (capacity about 12,000 m3). Because all harvested peat supplied to the plant is milled peat,
there is no crusher in the peat handling system. Figure 20 shows the peat delivery method (the intermediate
storage is not shown).
34
Figure 20. Peat delivery method
Two screw reclaimers under the storage area feed the conveyors, which take peat to two boiler silos. There are
two identical peat feeding lines in the boiler house each consisting of three feeding points on both side walls,
one day silo (200 m3 each), one drag chain conveyor, three feeding screws, and rotary feeders, three feeding
chutes to furnace.
Boiler technology
The Edenderry BFB boiler features the natural circulation operation principle and is equipped with a drum and a
reheater, which improves the overall plant efficiency. The boiler efficiency is 89.3%.
The bubbling fluidised bed boiler is particularly suited to combusting the rain soaked peat that is unavoidable
in the Irish climate. Even after a long rainy season peat burns well and support fuel is not needed. Four fuel oil
burners are used for start up.
In a BFB boiler the ash forming material leaves the furnace as fly ash with the flue gas. However, coarser impurities drop to the bottom of the bed and dense particles do not fluidise, so they must be removed from the furnace. The coarse material is collected via hoppers to two water-cooled screws. After the screws a drag chain
conveyor takes the material to a rail wagon for disposal.
Flue gas emissions control and emissions values
Air staging is the principal means of NOx control. A flue gas recirculation controls bed temperatures and thus
also affects positively NOx emissions. The NOx emission limit value is currently 325 mg/Nm3 (at 6% O2, dry gas)
and measured emission values are typically around 300 mg/Nm3.
SO2 removal is accomplished by limestone injection into the furnace. The SO2 emission limit value is currently
600 mg/Nm3 (at 6% O2, dry gas) and measured emission values are typically just below 600 mg/Nm3
Dust is removed by a one-chamber three-field electrostatic precipitator (ESP). The dust emission limit value is
currently 50 mg/Nm3 (at 6% O2, dry gas) and measured emission values are typically around 30 mg/Nm3.
Measured CO emission values are typically about 50 mg/Nm3 (at 6% O2, dry gas) during normal operation
(steady-state combustion conditions).
The current flue gas emission control methods, measured emission values and emission limit values valid in the
year 2004 are summarized in the following table.
35
Emission
Control method
Unit (at 6% O2,
dry gas)
Measurement result
NOx
SO2
Dust
CO
Air staging, flue gas recirculation
Limestone injection
ESP
Steady state combustion conditions
mg/Nm3
mg/Nm3
mg/Nm3
mg/Nm3
300
600
30
50
Limit
value
(2004)
325
600
50
-
Table 21. Summary of current flue gas emissions control methods and emission values
Dense phase pneumatic blowers convey ash from the ESP to the fly ash silo. The fly ash is fed via a moisturizing
screw from the silo to rail wagons and disposed of by returning it to the peat production areas for reclamation.
3.1.3 Lough Ree Power peat-fired power plant
General
The Lough Ree peat-fired power plant is currently under construction and will be commissioned in October
2004 in Lanesborough in County Longford. It will be a condensing power plant with a net electrical output of
about 91 MW. Auxiliary power consumption will be about 9 MW giving gross electrical output of max. 100 MW.
The boiler will be based on circulating fluidised bed (CFB) technology and fuelled with milled peat with an input
of about 245 MW. The boiler will supply steam (145/33 bar, 560/560°C) to a two-cylinder reheating condensing
steam turbine. Cooling water from the nearby river will be used to condense steam after the turbine. The overall
plant efficiency (net) will be about 38%.
The plant will be owned and operated by ESB, which also purchases the power.
The basic design data for the Lough Ree Power peat-fired power plant is shown in the following table and the
main process diagram in the following figure.
Fuel
Boiler type
Fuel input
Boiler efficiency
Gross power output
Net overall plant efficiency
Live steam parameters
Reheat steam parameters
Feed water
Flue gas end temperature and oxygen content
Milled peat
Circulating fluidised bed boiler, natural circulation with reheat
245 MW
90 %
100 MW (net 91 MW)
38 %
145 bar, 560 °C, 78 kg/s
33 bar, 560 °C, 71 kg/s
160 bar, 250 °C, 78 kg/s
160 °C and 3.0 % (dry)
Table 22. Basic design data for the Lough Ree Power peat-fired power plant
36
Figure 21. Main process diagram of the Lough Ree Power peat-fired power plant
Peat handling and storing
The Lough Ree Power plant is designed to burn about 0.8 million tonnes of milled peat per year with a 15-year
agreement from Bord na Mona. The price of peat supplied to the power plant is almost EUR 25/t equivalent to
about EUR 11.3/MWh at present (2003) and subjected to an increase of about 12% by the year 2010. The following table shows typical peat characteristics.
Carbon content (dry)
Hydrogen content (dry)
Nitrogen content (dry)
Sulphur content (dry)
Oxygen content (dry)
Ash content (dry)
Moisture content
Net Calorific Value
%
%
%
%
%
%
%
MJ/kg
51.6
5.2
1.4
0.4
35.4
6.0
54
7.5
Table 23. Typical peat characteristics
The pre-crushed peat will be supplied using a narrow gauge railway system and unloaded by a wagon tippler to
a receiving hopper. Railway wagon trains consisting of sixteen to twenty box type wagons, each wagon having
a nominal capacity of 16 to 18 m3 will be drawn by a diesel locomotive to and from the fuel off-loading facilities.
It will also be possible to supply peat by lorry, which will be unloaded to the receiving hopper. The lorries currently used vary in size; the smallest has a capacity of 80 m3 while the largest has a capacity of 100 m3. However,
the greater part of peat will be delivered by rail wagon. It is anticipated that 20-30% of peat will be delivered by
lorry.
37
Magnetic separators will remove metals and screens coarse particles before peat will be conveyed to the covered intermediate storage (capacity about 17,000 m3). Because all harvested peat supplied to the plant is milled
peat, there is no crusher in the peat handling system. The peat delivery method is similar to that of the
Edenderry plant (see Figure 20 for details).
Four screw reclaimers under the storage area will feed two conveyors, which will take peat to two boiler silos.
There will be two identical peat feeding lines in the boiler house.
Boiler technology
The Lough Ree Power CFB boiler features natural circulation operation principle equipped with a drum and a
reheater, which improves the overall plant efficiency. The boiler efficiency will be about 90%.
The circulating fluidised bed boiler will be particularly suited to combusting of the rain soaked peat that is unavoidable in the Irish climate. Even after a long rainy season peat burns well, and support fuel is not be needed.
Fuel oil burners will be used for start-up.
In a CFB boiler the ash forming material leaves the furnace as fly ash with the flue gas. However, coarser impurities drop to the bottom of the bed and dense particles do not fluidise, so they must be removed from the furnace. The coarse material is taken to a rail wagon for disposal.
Flue gas emissions control and emissions values
Air staging will be the principal means of NOx control. A flue gas recirculation will control bed temperatures and
thus also affect positively NOx emissions. It will also be possible to inject ammonia solution (30% NH3 and 70%
water) into the boiler in order to further reduce NOx emissions if needed. This method is known as a Selective
Non Catalytic Reduction (SNCR) process. The NOx emission limit value will be 200 mg/Nm3 (at 6% O2, dry gas).
SO2 removal will be accomplished by limestone injection into the furnace. An external flue gas desulphurization
(FGD) unit will be installed at the boiler outlet to reduce SO2 emissions when firing peat grades with very high
sulphur content. The SO2 emission limit value will be 200 mg/Nm3 (at 6% O2, dry gas).
Dust will be removed by a bag filter installed downstream of the FGD unit. The dust emission limit value will be
30 mg/Nm3 (at 6% O2, dry gas).
The NOx, SO2 and dust emission limit values will comply with those given in the EU directive 2001/80/EC on the
limitation of emissions of certain pollutants into air from large combustion plants.
CO emissions are expected to be typically about 50 mg/Nm3 (at 6% O2, dry gas) during normal operation
(steady-state combustion conditions).
Flue gas emission control methods and emission limit values are summarized in the following table.
Emission
Control method
NOx
Air staging, flue gas
recirculation, SNCR
Limestone injection,
FGD unit
Bag filter
Steady-state combustion conditions
SO2
Dust
CO
Unit (at 6% O2,
dry gas)
mg/Nm3
Emission value
200 (limit value)
mg/Nm3
200 (limit value)
mg/Nm3
mg/Nm3
30 (limit value)
50 (typical value)
Table 24. Summary of current flue gas emissions control methods and emission values
38
Dense phase pneumatic blowers will convey ash from the bag filter to the fly ash silo. The fly ash will be fed
from the silo to light rail wagons and disposed of by returning it to the peat production areas for reclamation.
3.1.4 West Offaly Power peat-fired power plant
General
The West Offaly Power peat-fired power plant is currently under construction and will be commissioned in
January 2005 in Shannonbridge in County Offaly. It will be a condensing power plant with a net electrical output of about 136 MW. Auxiliary power consumption will be about 14 MW giving gross electrical output of max
150 MW. The boiler will be based on circulating fluidised bed (CFB) technology and fuelled with milled peat
with an input of about 355 MW. The boiler will supply steam (170/33 bar, 560/560 °C) to a two-cylinder reheating condensing steam turbine. Cooling water from the nearby river will be used to condense steam after the
turbine. The overall plant efficiency (net) will be about 38%.
The plant will be owned and operated by ESB, which also purchases the power.
The basic design data for the West Offaly Power peat-fired power plant is shown in the following table and main
process diagram in the following figure.
Fuel
Boiler type
Fuel input
Boiler efficiency
Gross power output
Net overall plant efficiency
Live steam parameters
Reheat steam parameters
Feed water
Flue gas end temperature and oxygen content
Milled peat
Circulating fluidised bed boiler,
natural circulation with reheat
355 MW
90 %
150 MW (net 136 MW)
38 %
170 bar, 560 °C, 113 kg/s
33 bar, 560 °C, 104 kg/s
185 bar, 250 °C, 113 kg/s
160 °C and 3.0 % (dry)
Table 25. Basic design data for the West Offaly Power peat-fired power plant
39
Figure 22. Main process diagram of the West Offaly Power peat-fired power plant
Peat handling and storing
The West Offaly Power plant is designed to burn about 1.2 million tonnes of milled peat per year with a 15-year
agreement from Bord na Mona. The price of peat supplied to the power plant is almost EUR 25/t equivalent to
about EUR 11.3/MWh at present (2003) and subjected to an increase of about 12% by the year 2010. The following table shows typical peat characteristics.
Carbon content (dry)
Hydrogen content (dry)
Nitrogen content (dry)
Sulphur content (dry)
Oxygen content (dry)
Ash content (dry)
Moisture content
Net Calorific Value
%
%
%
%
%
%
%
MJ/kg
51.6
5.2
1.4
0.4
35.4
6.0
54
7.4
Table 26. Typical peat characteristics
The pre-crushed peat will be supplied using a narrow gauge railway system and unloaded by a wagon tippler to
a receiving hopper. Railway wagon trains consisting of sixteen to twenty box type wagons, each wagon having
a nominal capacity of 16 to 18 m3 will be drawn by a diesel locomotive to and from the fuel off-loading facilities.
It will also be possible to supply peat by lorry, which will be unloaded to the receiving hopper. The lorries currently used vary in size; the smallest has a capacity of 80 m3 while the largest has a capacity of 100 m3. However,
the greater part of peat will be delivered by rail wagon. It is anticipated that 20-30% of peat will be delivered by
lorry.
40
Magnetic separators will remove metals and screens coarse particles before peat will be conveyed to the covered intermediate storage (capacity about 22,000 m3). Because all harvested peat supplied to the plant is milled
peat, there is no crusher in the peat handling system. Peat delivery method is similar to that of the Edenderry
plant (see Figure 19 for details).
Four screw reclaimers under the storage area will feed two conveyors, which will take peat to two boiler silos.
There will be two identical peat feeding lines in the boiler house.
Boiler technology
The West Offaly Power CFB boiler features the natural circulation operation principle and is equipped with a
drum and a reheater, which improves the overall plant efficiency. The boiler efficiency will be about 90%.
The circulating fluidised bed boiler will be particularly suited to combusting of the rain soaked peat that is unavoidable in the Irish climate. Even after a long rainy season peat burns well and support fuel will not be
needed. Fuel oil burners will be used for start up.
In a CFB boiler the ash forming material leaves the furnace as fly ash with the flue gas. However, coarser impurities drop to the bottom of the bed and dense particles do not fluidise, so they must be removed from the furnace. The coarse material is taken to a rail wagon for disposal.
Flue gas emissions control and emissions values
Air staging will be the principal means of NOx control. A flue gas recirculation will control bed temperatures and
thus also affect positively NOx emissions. It will also be possible to inject ammonia solution (30% NH3 and 70%
water) into the boiler in order to further reduce NOx emissions if needed. This method is known as a Selective
Non Catalytic Reduction (SNCR) process. The NOx emission limit value will be 200 mg/Nm3 (at 6% O2, dry gas).
SO2 removal will be accomplished by limestone injection into the furnace. An external flue gas desulphurization
(FGD) unit will be installed at the boiler outlet to reduce SO2 emissions when firing peat grades with very high
sulphur content. The SO2 emission limit value will be 200 mg/Nm3 (at 6% O2, dry gas).
Dust will be removed by a bag filter installed downstream of the FGD unit. The dust emission limit value will be
30 mg/Nm3 (at 6% O2, dry gas).
The NOx, SO2 and dust emission limit values will comply with those given in the EU directive 2001/80/EC on the
limitation of emissions of certain pollutants into air from large combustion plants.
CO emissions are expected to be typically during normal operation (steady state combustions conditions) about
50 mg/Nm3 (at 6% O2, dry gas).
Flue gas emission control methods and emission limit values are summarized in the following table.
Emission
Control method
NOx
Air staging, flue gas
recirculation, SNCR
Limestone injection,
FGD unit
Bag filter
Steady state combustion conditions
SO2
Dust
CO
Unit (at 6% O2,
dry gas)
mg/Nm3
200 (limit value)
mg/Nm3
200 (limit value)
mg/Nm3
mg/Nm3
30 (limit value)
50 (typical value)
Emission value
Table 27. Summary of current flue gas emissions control methods and emission values
Dense phase pneumatic blowers will convey ash from the bag filter to the fly ash silo. The fly ash will be fed
from the silo to light rail wagons and disposed of by returning it to the peat production areas for reclamation.
41
3.1.5 Agreements, obligations, planning permissions, licensees
Edenderry, Lough Ree Power and West Offaly Power peat-fired power stations have 15-year power purchase
agreements with ESB PES for 100% of their output, back-to-back with a 15-year fuel purchase agreement from
Bord na Mona. The 15 year fuel purchase agreement between Bord na Mona and Edenderry Power Ltd. specifies
that the power plant accepts and/or pay for a minimum quantity of milled peat annually (1,000,000 tonnes per
year), based on a five year rolling average. It is understood by the Consultants that the agreements for West
Offaly and Lough Ree Power Plants are similarly structured.
The running of the peat-fired power plants is supported by a Public Service Obligation on all electricity users.
The new peat-fired power stations will require planning permission in order to burn any new/alternative fuel
(the situation regarding Moneypoint is less clear). They would also require a revision of their Integrated Pollution Prevention and Control (IPPC) licensees, issued by the Environmental Protection Agency (EPA).
3.2 Defining theoretical and technical co-firing potential by plant
3.2.1 Current theoretical maximum potential (based on combustion and boiler technology)
Moneypoint
Based on combustion and boiler technology at the Moneypoint power plant - coal combustion in pulverised
fuel boilers – current theoretical maximum biomass co-firing potential is estimated to be 10% of fuel input (fuel
energy).
The biomass that could be co-fired at the Moneypoint plant includes wood pellets and sawdust. Wood pellets
would be imported by bulk cargo ships, unloaded with existing facilities, stored in existing storage and
crushed/ground before feeding to the boiler using separate feeding system. Sawdust would be transported
locally by lorry, stored in the existing storage and crushed/ground before feeding to the boiler using a separate
feeding system.
The maximum potential of biomass (10% of fuel energy) equals the fuel input of roughly about 75 MW per
boiler totalling some 225 MW for three units. This amount of biomass requires that after crushing/grinding it
should be injected into the furnace with a separate feeding system using dedicated biomass burners.
Edenderry
Based on combustion and boiler technology at the Edenderry power plant – peat combustion in a bubbling
fluidised bed boiler – current theoretical maximum biomass co-firing potential is estimated to be 50% of fuel
input (fuel energy). The maximum potential of biomass (50% of fuel energy) equals the fuel input of roughly
about 150 MW.
The biomass that could be co-fired at the Edenderry plant includes sawmill residues (woodchips, bark and sawdust), forest residue chips (logging residue chips) and pre-crushed low quality pulpwood (small-diameter
roundwood). This kind of wood-based biomass would be transported locally by lorry and fed into the boiler
using existing peat handling equipment.
However, even though it has not been verified through testing that the peat handling system is capable of handling 50%, on an energy content basis, of wood-based biomass mixed with peat, it is assumed that no difficulties regarding the large amount of wood in the peat handling equipment would appear due to the similar composition and nature of these two fuels.
42
3.2.2 Current technical co-firing potential (based on plant technology and performance, current operational systems and equipment)
Moneypoint’s opportunities to use wood pellets
Moneypoint is integrated to the harbour enabling the direct unloading of cargo to the fuel store.
The Moneypoint coal-fired power plant has its own deep-water harbour enabling the intake of large-scale shipments of pellets. The length of the jetty is 380 m and water depth 25 m. Weight of cargo (DWT) of incoming coal
ships is usually 50,000 – 177,000 t. For operational reasons the minimum DWT of vessel to dock in has been
considered to be 17 000 tonnes. The unloading capacity of chips is 25,000 tonnes per day.
The ship unloading is done by two manually operated electro-hydraulic crane grabs. Cranes are travelling along
a common rail. Grabs feed two hoppers, which drop fuel to covered conveyors. Conveyors feed the fuel yard
consisting of several warehouses and open space storing facilities.
There is also one, currently unused fuel storage building with an estimated capacity of 5,000-10,000 m3, the interior of which was damaged in a fire. This could be fixed and used to store wood pellets and sawdust.
Moneypoint
Based not only on combustion and boiler technology but also on existing operational systems and equipment
at the Moneypoint power plant between the coal yard and the stack, current technical biomass co-firing potential is estimated to be about 5% of fuel input (fuel energy).
The biomass that could be co-fired at the Moneypoint plant includes wood pellets and sawdust, if available.
Wood pellets would be imported by bulk cargo ships, unloaded with existing facilities, stored in the existing
storage and fed to the boiler using the existing coal conveyors, bunkers, mills and burners. Sawdust would be
transported by lorry, stored in the existing storage and fed to the boiler using the existing coal conveyors, bunkers, mills and burners.
The technical potential of biomass (about 5% of fuel energy) equals the fuel input of almost 40 MW per boiler
totalling some 115 MW. It is expected that this amount of biomass could be blended with coal at the coal yard
and fed into the furnace using existing coal handling and feeding equipment such as conveyors, metal removal
equipment (magnets), bunkers, mills, burners, etc.
Moreover, it is also assumed that feeding of biomass using existing coal handling and feeding equipment could
be done without affecting boiler capacity as a consequence of possible limited coal mill capacity and without
impacting the sieve analysis of the mill product. However, this kind of arrangement will have to be verified with
biomass co-firing tests.
The moisture content of biomass intended to be co-fired in the Moneypoint plant shall not exceed 40%, which
indicates that the majority of biomass will have to be wood pellets the moisture content of which is only about
10% compared to that of sawdust (about 55%).
Another restriction in co-firing biomass in existing coal-fired power plants is the particle size. Based on operation experiences worldwide the maximum particle size of biomass before grinding shall be in the range of 5-10
mm depending on boiler operating conditions and grinding and burning equipment. It is anticipated that in
the Moneypoint plant the particle size of biomass delivered to the site is not be higher than 5 mm because the
particle size of wood pellets and sawdust is always less than that size. However, the effect of particle size on
grinding and combustion will have to be verified with biomass co-firing tests.
Edenderry
Based not only on combustion and boiler technology but also on existing operational systems and equipment
in the Edenderry power plant between the peat receiving station and the stack, current technical biomass co43
firing potential is estimated to be 20% of fuel input (fuel energy). The technical potential of biomass (20% of fuel
energy) equals the fuel input of roughly about 60 MW.
The biomass that could be co-fired in the Edenderry plant includes sawmill residues (woodchips, bark and sawdust), forest residue chips (logging residue chips) and pre-crushed low quality pulpwood (small diameter
roundwood). This kind of wood-based biomass would be transported locally by lorry and fed into the boiler
using existing peat handling equipment.
Biomass would be unloaded to the peat receiving hoppers, conveyed through the magnets and screens to the
peat storage and further on into the furnace using conveyors and boiler silos. The sawdust and wood chip test
carried out in the Edenderry plant a few years ago proved the peat handling system to be capable of handling a
fuel mixture of peat and woodchips/sawdust, up to a ratio of at least 30% wood.
3.2.3 Estimating technical co-firing potential in the future
3.2.3.1 Description of plant modification requirements (bottlenecks)
Moneypoint
Gasification and gas burning in the boiler (indirect co-firing) could be the most technically feasible solution for
co-firing biomass in the future (2010) due to its many advantages compared to the conventional direct co-firing
option as discussed earlier in this study (such as biomass ash is separate from coal ash, gasification does not
affect main boiler performance and availability, etc.). For these reasons, it is recommended that if the Moneypoint plant should decide to go ahead with co-firing with biomass in the future it should be based on gasification.
Based on operation experiences and biomass co-firing tests, technical biomass co-firing potential in the future
(2010) is estimated to be 15% of fuel input (fuel energy) in the Moneypoint power plant which is equal to biomass input of almost 115 MW per boiler totalling some 340 MW for three units.
In addition to industrial sawmill residues (woodchips, bark and sawdust), forest residue chips (logging residue
chips) and pre-crushed low quality pulpwood (small diameter roundwood), gasification allows to utilise also
wood-based short rotation coppice willow as fuel. This kind of local biomass can be transported by lorry, stored
in the existing storage of the coal-fired plant and unloaded to the fuel handling and feeding system of the gasification plant.
The moisture content of biomass intended to be gasified in the Moneypoint plant shall be less than 55% and
the particle size less than 50 mm.
The Moneypoint plant site is big enough at least for one gasification plant with required auxiliary equipment
and systems. Depending on the overall economics of the gasification process, the availability of biomass and
the site area availability, the Moneypoint plant could be equipped with one gasifier for one boiler or possibly
three gasifiers for three boilers. In any case, one gasifier produces syngas to be burnt through dedicated burners in one boiler. It is assumed that syngas will not have to be cleaned before burning in a boiler. Moreover, it is
foreseen that the gasification plant will not require any major modifications for the existing flue gas cleaning
equipment of the boiler plant.
Edenderry
Based on operation experiences and biomass co-firing tests, technical biomass co-firing potential in the future
(2010) is estimated to be 30% of fuel input (fuel energy) in the Edenderry power plant, which equals to biomass
input of roughly about 90 MW.
The biomass that could be co-fired in the Edenderry plant includes sawmill residues (wood chips, bark and sawdust), forest residue chips (logging residue chips) and pre-crushed low quality pulpwood (small diameter
roundwood).
44
This kind of wood-based biomass would be transported locally by lorry and fed into the boiler using existing
peat handling equipment. Biomass would be unloaded to the peat receiving hoppers, conveyed through the
magnets and screens to the peat storage and further on into the furnace using conveyors and boiler silos.
The moisture content of biomass intended to be co-fired in the Edenderry plant would be in the same range as
that of peat (around 55%) in order not to restrict the plant power output. Another restriction is the maximum
particle size of biomass after screens that should not exceed 40 mm because there is no crusher in the
Edenderry plant. If the particle size of biomass delivered to site were larger than 40 mm, a crusher would have
to be procured. It is foreseen that biomass co-firing will not require any major modifications to the existing
boiler plant and flue gas cleaning equipment.
Lough Ree Power and West Offaly Power
Based on operation experiences and biomass co-firing tests, technical biomass co-firing potential in the future
(2010) is estimated to be 30% of fuel input (fuel energy) in the Lough Ree Power and West Offaly Power plants
which is equivalent to biomass input of roughly about 70 MW in the Lough Ree Power and about 105 MW in
West Offaly Power.
The biomass that could be co-fired in the Lough Ree and West Offaly Power plants includes sawmill residues
(wood chips, bark and sawdust), forest residue chips (logging residue chips) and pre-crushed low quality pulpwood (small-diameter roundwood).
This kind of wood-based biomass would be transported locally by lorry and fed into the boiler using existing
peat handling equipment. Biomass will be unloaded to the peat receiving hoppers, conveyed through the
magnets and screens to the peat storage and further on into the furnace using conveyors and boiler silos.
The moisture content of biomass intended to be co-fired in the Lough Ree Power and West Offaly Power plants
should be in the same range as that of peat (around 55%). Another restriction is the maximum particle size of
biomass after screens that should not exceed 50 mm because there is no crusher in the Lough Ree Power and
West Offaly Power plants. If the particle size of biomass delivered to site were larger than 50 mm, a crusher
would have to be procured. It is foreseen that biomass co-firing will not require any major modifications to the
existing boiler plant and flue gas cleaning equipment.
3.2.3.2 Investments needed for existing systems and equipment and new installations to increase biomass utilization possibilities (to a technically feasible level)
Moneypoint
The procurement of the gasification plant for one boiler implements the substitution of biomass to the assessed
technical feasible level in 2010, which is approx. 15% of fuel input (equivalent to approx.110 MW). The total investment cost estimate for the complete gasification plant with all auxiliary equipment installed and commissioned in one boiler of the Moneypoint power plant is about EUR 20 million.
Edenderry
The technical feasible biomass co-firing level in 2003 and 2010 is assessed to be approx. 30% of fuel input
(equivalent to approx. 90 MW). If the particle size of biomass delivered to site were larger than 40 mm, a crusher
would have to be procured. The total investment cost estimate for the crusher with all auxiliary equipment installed and commissioned in the Edenderry power plant is about EUR 200,000.
Lough Ree Power and West Offaly Power
The technical feasible biomass co-firing level in 2010 is assessed to be approx. 30% of fuel input (equivalent to
approx. 70 MW in Lough Ree Power and 105 MW in West Offaly Power). If the particle size of biomass delivered
to site were larger than 50 mm, a crusher would have to be procured. The total investment cost estimate for the
crusher with all auxiliary equipment installed and commissioned in the Lough Ree or West Offaly power plant is
about EUR 200,000.
45
3.2.4 Summary
The following two tables summarize biomass requirements and co-firing potential with biomass in the power
plants studied in this study.
Moneypoint
Edenderry
West Offaly
Power
Lough Ree Power
Particle size
direct co-firing: pellets, sawdust, max. size 5 mm
indirect co-firing: wood chips,
bark, sawdust, forest residues,
willow, max. size 50 mm
wood chips, bark,
sawdust, forest
residues, max.
size 40 mm
wood chips,
bark, sawdust,
forest residues,
max. size 50
mm
wood chips, bark,
sawdust, forest
residues, max. size
50 mm
Moisture content
direct co-firing: < 40%
indirect co-firing: < 55%
< 60%
< 60%
< 60%
Homogenous
direct co-firing: important
indirect co-firing: not important
not important
not important
not important
Table 28. Fuel requirements
Moneypoint
% of total fuel input
GWh fuel
Edenderry
% of total fuel input
GWh fuel
West Offaly Power
% of total fuel input
GWh fuel
Lough Ree Power
% of total fuel input
GWh fuel
Total
% of total fuel input
GWh fuel
Current Theoretical
potential in 2003 (boiler
capability)
Current Technical potential in 2003 (plant
operational restrictions)
Future Technical potential in 2010 (plant
operational restrictions
after selected modification investments)
10 (direct)
560/1680 (1/3 units)
5 (direct)
280/840 (1/3 units)
15 (indirect)
840/2520 (1/3 units)
50
1140
20
460
30
690
30
800
30
550
10-50
1700/2820
5-20
740/1300
15-30
2880/4560
Table 29. Co-firing potential with biomass
3.3
Defining biomass fuel paying capability by plant
3.3.1 Current situation
At present, Ireland is not directly supporting co-firing of biomass in peat or coal fired power stations. This means
that if power plants (under review in this study) want to start co-firing, the biomass prices must be competitive
with the fossil fuels used. In fact, biomass-based fuel purchase prices should be lower than the main fuel in or46
der to be able to carry the extra costs involved with biomass use (licensing, quality control, fuel purchasing etc.).
On the other hand, introducing biomass has also some positive effects on environmental implications of SO2
emissions (see section 4 for details), which will improve the competitiveness of biomass against fossil fuels.
Moneypoint
Edenderry
West Offaly Power
Lough Ree Power
1)
Coal 1)
EUR/MWh
5
-
Peat
EUR/MWh
11.7
11.7
11.7
Biomass
EUR/MWh
≤5
≤ 11.7
≤ 11.7
≤ 11.7
Estimation made by the Consultant (world market price of coal)
Table 30. Average fuel prices in 2003 and equivalent fuel price for biomass-based fuel
3.3.2 Future situation with fuel / energy-production subsidies / taxes and emission trading
At present, Ireland has no carbon energy taxation. The Government has announced the intention to introduce a
carbon energy tax from the end of 2004. The Government published a consultation paper inviting submissions,
with a deadline of 30th September 2003. It is proposed that an excise-type tax will be placed on all fossil fuels.
However, it is envisaged that any company involved in the EU emissions trading scheme will not be subject to
the carbon energy tax. Therefore, the power plants under review in this study will not be impacted by the introduction of a carbon energy tax.
Average fuel purchase prices in 2003 for peat were between EUR 11.1 and 11.3/MWh and for coal EUR 5/MWh
(average world market price). Price development of fuel peat is index-linked with average earnings (55%),
wholesale price (20%), coal price (11%), heavy fuel oil price (4.25%) and natural gas price (9.75%).
According to the Consultant’s own estimation, the fuel prices in 2010 would be EUR 12.7/MWh for peat and EUR
5.3/MWh for coal.
Ireland has committed to limiting the growth in greenhouse gas emissions by the period 2008-2012 to 13%
above base year (1990) emissions. The EU Emissions Trading Directive (Directive 2003/87/EC) is being implemented to assist in achieving the target. In July 2003 the Environmental Protection Agency was assigned the
responsibility for implementing this Directive in Ireland. Ireland’s National Allocation Plan 2005-2007 was notified to the Commission on 31st March 2004. The following table shows the amount of historic emissions and the
emissions to be allocated for free as indicated in the National Allocation Plan, 2005-2007 for the power plants
under review in this study.
47
Allocations of Individual Installations
Relevant and Historic Emissions, t of CO2
Relevant
Emission
2000
2001
2002
2003
2005
2006
2007
% of
relevant
emissions
Lough Ree Power
756 000
-
-
-
-
557 271
557 271
557 271
73.7
West Offaly Power
1 134 000
-
-
-
-
835 907
835 907
835 907
73.7
Edenderry
796 241
-
824 740
824 603
767 878
586 934
586 934
586 934
73.7
Moneypoint
5 700 230
5 878 955
6 075 649
5 905 459 5 495 000 4 201 816
4 201 816 4 201 816 73.7
Table 31. Relevant emissions and allocations for free, t of CO2.
The power plants, which are the subject of this study, have been allocated 73.7 % of their “relevant emission”.
This means that, for example, the Moneypoint Power Plant would need to reduce emissions by means of purchasing 1.5 Mt of CO2 emissions reductions from the emissions trading markets or by means of replacing some
664 000 t of coal (4.6 TWhfuel) by biomass.
Plant
Lough Ree Power
West Offaly Power
Edenderry
Moneypoint
Capacity
(MWe)
Fuel
100
150
120
900
Peat
Peat
Peat
Coal
GHG under
trade,
t of CO2
198 729
298 093
209 307
1 498 414
Conversion
factor
gCO2/MJfuel
108.42
108.42
108.42
90.2
Fuel under
trade,
GWhfuel
509
764
536
4 614
Fuel under
trade, 1000
t
238
357
251
664
Table 32. Amount of CO2 under carbon trading scheme.
Emissions trading will start at the beginning of 2005.
In this study the effect of emission costs (to be purchased under emission trading scheme) on the competitiveness of fuel peat, coal and wood-based fuel will be analysed based on four different cost levels: EUR 0, 10, 20
and 30/t carbon. The analysis is based on the following carbon contents: 108.42 (gCO2/MJfuel) for fuel peat and
90.2 (gCO2/MJfuel) for coal.
The effect of different carbon cost levels on the biomass-based fuel paying capability can be seen in the following figures.
48
Blue colour = year 2003; Red colour = year 2010
Figure 23 Effect of emission trading on biomass-based fuel paying capability in peat-fired power plants
Figure 24 Effect of emissions trading on fuel paying capability at Moneypoint
49
The estimated fuel purchase prices in 2003 and in 2010 as well as the effect of EUR 10, 20 and 30/t CO2 cost levels on the biomass-based fuel paying capability can be seen in the following table.
EUR 0 /t CO2
EUR 10/t CO2
EUR 20 /t CO2
EUR 30 /t CO2
2003
Peat
11.3
15.2
19.1
23.0
Coal
5
8.2
11.5
14.7
2010
Peat
12.7
16.6
20.5
24.4
Coal
5.3
8.5
11.7
15
Table 33. Effect of emissions trading on the biomass-based fuel paying capability
50
4 Environmental Impact
4.1 Boiler plant performance and emissions
4.1.1 Without biomass co-firing
Performance and emissions calculations of the boiler plants without biomass co-firing considered in this study
(Moneypoint, Edenderry, Lough Ree Power and West Offaly Power) are based on the coal and peat analyses and
basic technical/design data of these plants given in section 3.1.
The following table shows fuel, fuel input, fuel consumption, efficiency (based on the standard DIN 1942) and
theoretical (without any reduction method) SO2 (mg/Nm3 at 6% O2, dry gas) and CO2 (Mt/a) emissions of the
boiler plants without co-firing.
Fuel
Fuel input,
MW
Fuel cons.,
GWh/a
Efficiency,
%
SO2,
mg/Nm3
CO2,
Mt/a
Moneypoint
Coal
760 (100%)
5700
93.4
1180 *
1.85
Edenderry
Peat
300 (100%)
2250
89.4
1015 **
0.88
Lough Ree
Power
Peat
240 (100%)
1800
90.0
1082 ***
0.70
West Offaly
Power
Peat
360 (100%)
2700
90.0
1082 ***
1.05
Table 34. Performance and emissions of the boiler plants
* Theoretical emissions without any reduction method, the emission limit value is 1800 mg/Nm3 as annual average.
** Theoretical emissions without limestone injection, measured emission level is about 40% lower due to limestone injection to meet the current emission limit value of 600 mg/Nm3.
*** Theoretical emissions without limestone injection, the emission limit value of 200 mg/Nm3 will be met by
limestone injection and a FGD unit, if needed.
4.1.2 With biomass co-firing
The performance and emissions calculations of the boiler plants with biomass co-firing under review in this
study (Moneypoint, Edenderry, Lough Ree Power and West Offaly Power) are based on the coal and peat analyses and basic technical/design data of these plants given in section 3.1.
Potential biomass that is technically the most suitable for co-firing includes wood and wood pellets. Wood is
considered here as a mixture of sawmill residues (bark, woodchips, sawdust), low-quality pulpwood (smalldiameter roundwood) and forest residues (harvesting residues). The analyses of wood and wood pellets used in
the calculations are shown in the following table.
51
Carbon content (dry)
Hydrogen content (dry)
Nitrogen content (dry)
Sulphur content (dry)
Oxygen content (dry)
Ash content (dry)
Moisture content
Net Calorific Value
%
%
%
%
%
%
%
MJ/kg
Wood
50.0
6.0
0.4
0.05
42.55
1.0
57.7
6.9
Wood pellets
50.0
6.3
0.3
0.05
42.85
0.5
10.0
17.3
Table 35. Typical wood and wood pellets characteristics
Short rotation coppice willow has not been considered in these calculations due to its non-availability at the
moment and small amount and high price in the future. Technically willow could only be used at Moneypoint
by co-firing it indirectly (gasification).
4.1.2.1 Current theoretical potential (maximum, no modifications)
The following table shows fuel, fuel input, fuel consumption, efficiency (based on the standard DIN 1942) and
theoretical (without any reduction method) SO2 (mg/Nm3 at 6% O2, dry gas) and CO2 (Mt/a) emissions of the
boiler plants with current theoretical biomass co-firing potential (maximum, no modifications).
Fuel
Fuel input,
MW
Fuel cons.,
GWh/a
Efficiency,
%
SO2,
mg/Nm3
CO2,
Mt/a
Moneypoint (direct cofiring)
Coal
Pellets
Total
686 (90%)
76 (10%)
762 (100%)
5145
570
5715
93.2
1087
1.67
Edenderry
Peat
Wood
Total
150 (50%)
150 (50%)
300 (100%)
1125
1125
2250
89.4
605
0.44
Table 36. Boiler plants performance and emissions
4.1.2.2 Current technical (no modifications)
The following table shows fuel, fuel input, fuel consumption, efficiency (based on the standard DIN 1942) and
theoretical (without any reduction method) SO2 (mg/Nm3 at 6% O2, dry gas) and CO2 (Mt/a) emissions of the
boiler plants with current technical biomass co-firing potential (no modifications).
52
Moneypoint
(direct cofiring)
Edenderry
Fuel
Fuel input,
MW
Fuel cons.,
GWh/a
Efficiency,
%
SO2,
mg/Nm3
CO2,
Mt/a
Coal
Pellets
Total
723 (95%)
38 (5%)
761 (100%)
5425
285
5710
93.3
1133
1.76
Peat
Wood
Total
240 (80%)
60 (20%)
300 (100%)
1800
450
2250
89.4
856
0.70
Table 37. Boiler plants performance and emissions
4.1.2.3 Summary
In comparison to coal firing there will be a minor reduction in the boiler efficiency at Moneypoint when 5 or
10% of coal (energy content) is replaced with wood pellets because wood pellets have a lower net calorific
value than that of coal. For this reason, a little bit more fuel has to be fed into the boiler in order to keep the
steam output constant and thus not to reduce the electricity output. However, it is possible that due to the capacity of the coal mills the electricity output of the plant has to be reduced slightly which can cause an annual
net electricity output loss.
In comparison to peat firing it is assumed that there will be no changes in the boiler efficiency, fuel input and
steam/electricity output in Edenderry when 20 or 50% of peat (energy content) is replaced with wood because
the net calorific value of wood is very close to that of peat.
Replacing coal and peat, which contain sulphur, with almost sulphur-free wood will reduce the SO2 emissions
with a corresponding proportion and reduction in limestone consumption. At Moneypoint the SO2 emission
reduction will be about 4 or 8% and in Edenderry about 15 or 40% from the theoretical emissions depending on
the amount of biomass to be co-fired with coal and peat. At Moneypoint there is no SO2 removal method in operation at the moment and the SO2 emissions are already below the current emission limit value (1800 mg/Nm3
as annual average). In Edenderry this means that depending on the amount of biomass no limestone injection
or smaller amount of limestone would be required to meet the current SO2 emission limit value (600 mg/Nm3),
which saves limestone costs.
Because wood-based biomass fuels are considered as CO2 neutral in terms of CO2 balance in the atmosphere,
CO2 emissions reduction will be equivalent to the proportion of wood or wood pellets in the entire fuel mixture.
At Moneypoint the CO2 emissions reduction will be about 5 or 10% and in Edenderry about 20 or 50% from the
theoretical emissions depending on the amount of biomass to be co-fired with coal and peat.
In comparison to peat firing it is assumed that NOx emissions will not increase because of the lower nitrogen
content of wood compared to peat, which should reduce NOx emissions in Edenderry where the majority of NOx
originates from fuel nitrogen. At Moneypoint there will probably be no change in the current NOx emission level
as a consequence of co-firing due to the fact that the majority of NOx originates from air present in the combustion process. The current NOx emission levels and limit values are presented in the section 3.1.
In comparison to coal and peat firing it is assumed that there will be no changes in dust emissions to air in both
Moneypoint and Edenderry. This is because the dust load before the ESP reduces as the ash content of wood
pellets and wood is lower than that of coal and peat, which should improve the collection efficiency of the ESP
and thus at least in theory lower slightly the dust emission level into air. The current dust emission levels and
limit values are presented in the section 3.1.
Biomass co-firing will also cause a small change in the fly and bottom ash composition, which has an impact on
the end use of fly ash at Moneypoint, where it will be reused as a raw material in the cement factory. The current
requirements of the national standards in Ireland are that the loss of ignition shall not exceed 7% and the
source of ash must be from coal. These requirements may prevent the use of fly ash derived from co-firing with
53
biomass. The bottom ash from Moneypoint and both ashes (fly and bottom) from Edenderry are transported to
the ash disposal areas where the small changes in ash composition are not so critical and should have no direct
implications for this kind of end use.
4.1.2.4 Future technical (with modifications)
The following table shows the fuel, fuel input, fuel consumption, efficiency (based on the standard DIN 1942)
and theoretical (without any reduction method) SO2 (mg/Nm3 at 6% O2, dry gas) and CO2 (Mt/a) emissions of the
boiler plants with future technical biomass co-firing potential (with modifications).
Fuel
Fuel input,
MW
Fuel cons.,
GWh/a
Efficiency,
%
SO2,
mg/Nm3
CO2,
Mt/a
Moneypoint
(indirect cofiring)
Coal
Wood
Total
649 (85%)
114 (15%)
763 (100%)
4870
855
5725
93.1
1015
1.57
Edenderry
Peat
Wood
Total
210 (70%)
90 (30%
300 (100%)
1575
675
2250
89.4
774
0.62
Lough Ree
Power
Peat
Wood
Total
168 (70%)
72 (30%)
240 (100%)
1260
540
1800
90.0
812
0.49
West Offaly
Power
Peat
Wood
Total
252 (70%)
108 (30%)
360 (100%)
1890
810
2700
90.0
812
0.74
Table 38. Boiler plants performance and emissions
In comparison to coal firing there will be a minor reduction in boiler efficiency at Moneypoint when 15% of coal
(energy content) is replaced with wood by gasifying it because the net calorific value of wood is lower than that
of coal. For this reason, a little bit more fuel has to be fed into the boiler in order to keep the steam output constant and thus not reduce the electricity output. Moreover, as electricity is needed for the gasification plant’s
auxiliary power consumption and the efficiency of the gasification process is about 98%, the net electricity output of the power plant will reduce slightly.
In comparison to peat firing it is assumed that there will be no changes in the boiler efficiency, fuel input and
steam/electricity output in Edenderry, Lough Ree Power and West Offaly Power when 30% of peat (energy content) is replaced with wood because the net calorific value of wood is very close to that of peat.
Replacing coal and peat, which contain sulphur, with almost sulphur-free wood will reduce the SO2 emissions
with a corresponding proportion and reduction in limestone consumption. At Moneypoint the SO2 emission
reduction will be about 15% and in Edenderry, Lough Ree Power and West Offaly Power about 25% from the
theoretical emissions. At Moneypoint there is no SO2 removal method in operation at the moment and the SO2
emissions are already below the current emission limit value (1800 mg/Nm3 as annual average). In Edenderry,
Lough Ree Power and West Offaly Power this could mean that smaller amount of limestone would be required
to meet the current SO2 emission limit value (Edenderry: 600 mg/Nm3; Lough Ree Power and West Offaly Power:
200 mg/Nm3), which saves limestone costs.
Because wood-based biomass fuels are considered as CO2 neutral in terms of CO2 balance in the atmosphere,
CO2 emissions reduction will be equivalent to the proportion of wood in the entire fuel mixture. At Moneypoint
the CO2 emissions reduction will be about 15% and in Edenderry, Lough Ree Power and West Offaly Power
about 30% from the theoretical emissions.
54
In comparison to peat firing it is assumed that NOx emissions will not increase because the nitrogen content of
wood is lower than that of peat, which should reduce NOx emissions in Edenderry, Lough Ree Power and West
Offaly Power, where the majority of NOx originates from fuel nitrogen. At Moneypoint there will probably be no
changes in the current NOx emission level as a consequence of co-firing due to the fact that the majority of NOx
originates from air present in the combustion process. Based on operating experiences, it is, however, possible
that the NOx emission level might decrease slightly due to the re-burning effect caused by the product gas in
the boiler. The current NOx emission levels and limit values are presented in section 3.1
In comparison to coal and peat firing it is assumed that there will be no changes in dust emissions to air from
Moneypoint, Edenderry, Lough Ree Power and West Offaly Power. This is because the dust load before the dust
removal equipment reduces as the ash content of wood is lower than that of coal and peat, which should improve the collection efficiency of dust removal equipment and thus at least in theory lower slightly the dust
emission level into the air. The current dust emission levels and limit values are presented in section 3.1.
Indirect co-firing (gasification) of biomass will cause no changes in the fly and bottom ash composition because
ashes derived from the gasification and boiler plants do not mix with each other. Therefore, gasification has no
effect on the current end use of fly ash at Moneypoint where it will be reused as a raw material in the cement
factory. The bottom ashes of the boiler and gasification plants at Moneypoint and both ashes (fly and bottom)
in Edenderry, Lough Ree Power and West Offaly Power will be transported to the ash disposal areas, where the
small changes in the ash composition are not so critical and should have no direct effect on this kind of end use.
55
5
Economic Implications
5.1
Present situation
5.1.1 Peat production and usage
The peat production period starts in April and ends in October. The only peat producer is the state-owned company Bord na Mona (BnM). Annual production of milled peat is about 4 Mt in Ireland, of which more than 3 Mt is
for energy generation to be used at the three peat-fired power plants as follows:
− Edenderry:
− Lough Ree Power:
− West Offaly Power:
1.0 Mt/a
0.84 Mt/a
1.2 Mt/a
Briquette plants and direct consumption use annually about 1 Mt of milled peat.
It is expected that the total peat production area of 85,000 hectares to produce 4 Mt of milled peat will remain
unchanged in the future (at least by 2015). Annual changes in peat production can be large due to weather conditions. There are some large production areas but also many separate small areas. It is not foreseen that there
will be new production areas but the present smaller areas may be linked to each other to form larger areas.
5.1.2 Peat transportation
Milled peat is transported to the power plants by train and lorry. Bord na Mona (BnM) owns all trains and lorries
used currently in peat transportation, and all workers involved in peat transportation are BnM employees. In
Edenderry all peat has so far been delivered by rail wagons. It is anticipated that no peat will be delivered by
lorry in future either. In Lough Ree Power and West Offaly Power the major part of peat will be delivered by rail
wagons. It is anticipated that 20-30% of peat will be delivered by lorry.
The railway wagon train consists of sixteen to twenty box type wagons. Each wagon has a nominal capacity of
16 to 18 m3 with a total train capacity of 260 to 360 m3. It is assumed that this system will remain unchanged in
the future. The lorries currently used vary in size; the smallest has a capacity of 80 m3 while the largest has a capacity of 100 m3. Due to the increased amount of lorry transportation in the future it is anticipated that, in addition to its own lorries, BnM will also have subcontractors to carry out this task. An average peat transportation
distance from production areas to power plants is now 60-80 km and will also be roughly the same in the future.
5.1.3 Employment impact of peat
BnM currently employs 1850 permanent staff and up to 600 additional regular seasonal staff for between 14
and 26 weeks annually during the production period. These people are mainly farmers. Over 70% of the total
staff is involved in peat-to-energy related activities. The rest are in involved in management, horticulture and
engineering areas.
In addition to these figures, peat also results in the employment of staff at the three peat-fired power plants.
There are currently about 50 employees at the Edenderry power plant. Based on this, it is expected that the two
new peat-fired power plants under construction – Lough Ree Power and West Offaly Power will employ in total
some 100 employees. This gives a total staff of about 150 employees in peat-to-energy generation.
5.1.4 Role of peat
Although peat covers only 7% of total primary energy requirement in Ireland, its role in energy policy is important because it is the only significant indigenous fuel in Ireland. All the other major primary energy sources – oil,
natural gas and coal – are mainly imported. Moreover, the direct and indirect employment impact of peat pro56
duction and transportation as well as peat-to-energy generation is very important in Ireland. According to the
economic input-output analysis carried out, for example, in Finland, indirect employment impacts seem quite
often to be on the same level as direct employment impacts.
Therefore, it is assumed that the importance of peat will remain on the current level in the Irish economy in the
future, for at least the next ten years (up to 2015) independent of the impact of the yet to be ratified Kyoto
Process, the EU Emissions Trading Directive and its implementation with related effects on Irish legislation.
5.2
Co-firing with biomass
At present, the coal and peat-fired power plants have a unique role in the economic life of Ireland. The production of peat is a protected activity and the costs of electricity generation from it are recovered under a Public
Service Obligation, as a result of which any substitution of biomass for peat needs to consider the employment
implications. However, the production of biomass creates new job opportunities in production and transportation.
It is, however, very difficult to quantify accurately the employment implications of biomass because they depend largely on the type of biomass. For example, if biomass consisted mainly of sawmill residues and wood, it
could be expected that almost no new jobs in production would be created. On the other hand, if biomass consisted mainly of forest residues it could be expected that some new jobs would be created.
In comparison to both coal and peat, most biomass fuels have significantly lower energy densities, they are
bulky and frequently wet. As a result, they present potential infrastructure problems, especially, with respect to
transport. It could be that existing logistic systems may be able to accommodate biomass with little difficulty, or
it could be that new transport systems would need to be introduced. This would largely depend on the geographic distribution of biomass supplies and on the point in the supply chain at which biomass could be processed to reduce its bulk and increase its energy density.
When taking into account a few lost jobs in peat production and transportation as a result of biomass co-firing it
can be concluded that the net change in the number of employees would be negligible. Moreover, co-firing of
biomass in the coal and peat-fired power plants is not assumed to have employment implications for the operation and maintenance of these plants.
57
6
Theoretical and Technical Biomass Supply Potential
The focus of this study is to analyse the availability of solid wood-based biomass including forest residues (logging and thinning residues), low-quality pulpwood (low-diameter roundwood), sawmill residues and willow
from short rotation coppice plantations and wood pellets from overseas sources. Other biomass types i.e. straw
from grain crops, chicken litter, spent mushroom compost, tallow and meat and bone meal are to be dealt on a
more general level.
Each of these sources is presented in terms of total quantities (theoretical potential) produced in 2003 and estimated total quantities in 2010. In addition, quantities available for energy production purposes (technical potential) is presented considering alternative uses of the biomass resource as well as the technical and ecological
availability constraints of each resource.
The energy values, used in this study, to calculate the energy content of each fuel type are presented in the
following table.
Sawmilling by-products
MJ/kg (dm)
MWh/t (dm)
moist, %
ash, %
MWh/t (fresh)
MJ/kg (fresh)
GJ/t (fresh)
For.Chips Chips
19,5
19,5
5,42
5,42
60
57
2
0,5
1,76
1,94
6,34
6,99
6,34
6,99
Bark
20
5,56
57
1
2,00
7,21
7,21
Dust
Pellets
19,5
19,5
5,42
5,42
57
10
0,5
0,5
1,94
4,81
6,99
17,31
6,99
17,31
SRC
Straw
19,2
17,4
5,33
4,83
60
20
2
5
1,73
3,73
6,22 13,43
6,22 13,43
Litter
SMC MBM Tallow
15
12,9
16,2
40
4,17
3,58
4,50
11,11
35
68
8
10
7
35
28,3
0,1
2,47
0,69
4,09
9,93
8,90
2,47 14,71
35,76
8,90
2,47 14,71
35,76
Table 39. The energy values of selected biomass-based fuels
In this study standard Coillte conversion factor of 1.11 solid-m3 to one wet tonne has been used to convert volumes to weights.
6.1
Summary
Total theoretical indigenous biomass resource potential (excluding wood pellets) in 2003 was about 13.5 TWh (5.5
Mt fresh), the amount of which is predicted to increase to 15.2 TWh (6.7 Mt fresh) by the year 2010. This amount
of fuel in 2010 would be sufficient to fuel an electricity production plant with a capacity of 665 MWe (operating
hours: 7500 h/a, efficiency: 0.37). The share of wood-based biomass is 6.2 TWh (3.4 Mt) in 2003 and 8.5 TWh (4.7
Mt) in 2010. Wood–based biomass would be sufficient for an electricity production capacity of 417 MWe.
Technical biomass resource potential was 2.2 TWh fuel (0.9 Mt fresh, 110 MWe) in 2003 and is expected to be 3
TWh fuel (1.4 Mt fresh, 150 MWe) in 2010. The share of wood-based biomass was 1.1 TWh (0.6 Mt) in 2003 and is
expected to be 1.9 TWh (1 Mt) in 2010.
The most promising wood-based biomass resource potential in the year 2010 includes pulpwood (low-quality
and small-diameter roundwood) with 728 GWhfuel technical availability, followed by sawmill residues (624
GWhfuel), harvesting residues (443 GWhfuel) and short rotation coppice (SRC) willow (99 GWhfuel).
Electricity capacity has been calculated assuming that annual peak load is 7 500 hours and electricity efficiency
37%.
58
1000 t/a 1000 s-m3/a
PJ (fuel)
fresh
fresh
Pulpwood
Theoretical
2003
1 209
Technical
2003
132
Theoretical
2010
1 596
Technical
2010
414
Sawmill residues (bark, sawdust, chips)
Theoretical
2003
1 174
Technical
2003
266
Theoretical
2010
1 223
Technical
2010
315
Harvesting residues
GWh
(fuel)
Electricity
MWe
1 343
146
1 773
459
7,7
0,8
10,1
2,6
2 128
231
2 808
728
105
11
139
36
1 305
296
1 359
350
8,2
1,9
8,6
2,2
2 292
528
2 389
624
113
26
118
31
Theoretical
2003
1 029
1 143
6,5
1 810
89
Technical
2003
216
240
1,4
380
19
Theoretical
2010
1 200
1 333
7,6
2 111
104
Technical
2010
Meat and Bone Meal
Theoretical
2003
252
280
1,6
443
22
150
0
2,2
613
30
2003
2010
2010
75
135
68
0
0
0
1,1
2,0
1,0
306
552
276
15
27
14
2003
2003
2010
2010
137
35
137
35
1,2
0,3
1,2
0,3
340
86
340
86
17
4
17
4
1 155
99
57
5
5 328
266
5 001
400
263
13
247
20
199
63
199
63
10
3
10
3
775
367
705
328
38
18
35
16
13 484
2 230
15 259
3 048
665
110
753
150
6 230
1 140
8 462
1 894
307
56
417
93
Technical
Theoretical
Technical
Chicken litter
Theoretical
Technical
Theoretical
Technical
Short Rotation Coppice (Willow)
Theoretical
2003
Technical
2003
Theoretical
2010
669
743
4,2
Technical
2010
57
64
0,4
Straw
Theoretical
2003
1 428
19,2
Technical
2003
71
1,0
Theoretical
2010
1 340
19,2
Technical
2010
107
1,4
Spent Mushroom Compost
Theoretical
2003
290
0,7
Technical
2003
93
0,2
Theoretical
2010
290
0,7
Technical
2010
93
0,2
Tallow
Theoretical
2003
78
2,8
Technical
2003
37
1,3
Theoretical
2010
71
2,5
Technical
2010
33
1,2
TOTAL RESOURCE POTENTIAL
Theoretical
2003
5 495
3 791
49
Technical
2003
924
682
8
Theoretical
2010
6 661
5 208
56
Technical
2010
1 373
1 153
11
WOOD-BASED BIOMASS RESOURCE POTENTIAL
Theoretical
2003
3 412
3 791
22,4
Technical
2003
613
682
4,1
Theoretical
2010
4 687
5 208
30,4
Technical
2010
1 038
1 153
6,8
59
Table 40 Energy potential of biomassbased fuels
6.2
Availability of wood-based biomass
There are five principal potential sources of wood fuel:
•
•
•
•
•
sawmill residues
small-diameter roundwood
forest residues (logging and thinning residues)
short rotation coppice plantations
wood pellets from overseas sources
6.2.1 Forest resources
The island of Ireland has a forest cover of 785,000 ha. Coillte Teoranta, the State forestry company, owns
440,000 hectares (56%); The Northern Ireland Forest Service owns 61,000 hectares (8%); while a further 284,000
hectares (36%) is in private ownership3.
The Government policy is to convert annually 20,000 hectares of land to forestry until the year 2030. This will
increase the forested area from the present 9% to 17% by 2030. The share of the state-owned forest is declining
as private owners now account for the major part of new planting. Plantations make up almost the whole forest
area, which means that virtually all forest is available to wood supply.
The species distribution is known for the forests owned and managed by both Coillte and the Northern Ireland
Forest Service (NIFS). They represent 60% of the forest estate on the island. The remaining 40% is privately
owned and its species distribution is not available at present.
Figure 25. Species Distribution, Coillte Estate Forested Area
Standing volume (growing stock) of trees is about 44 million solid-m3 (over bark) and annual increment (yield)
about 3.8 million solid-m3 (about 6 m3/ha) in the ROI 4. Based on Consultant’s estimation the total annual woodbased biomass yield would be about 5.8 million s-m3 comprising of 3.8 million m3 of roundwood, 1.0 million m3
of branches and tree tops and about 0.9 million m3 of stumps and roots.
3
4
Report of the Timber industry Development Group
European Forest Institute, Forest resources of Ireland
60
Commercial roundwood
Branches and tree tops
Stumps and roots
Total
*) Source: Consultant’s own estimation
Spruce, fir
Pine
2 287
709
595
3 590
762
160
183
1 105
Broadleaved
762
137
175
1 075
Total
3 811
1 006
953
5 770
Table 41 Annual increment of biomass excluding green matter, 1000 s-m3 (ob), 2000, ROI
Forest biomass types, related to commercial roundwood production, that are in theory available for energy production purposes consist of branches and tree tops, stems and roots and low-quality tree stems. The green
matter consisting of needles and leaves is not included in the energy potential as this material should be left to
forest to maintain the nutrient balance. Forest biomass energy potential is presented in the following table.
Spruce, fir
Pine
Low-quality roundwood *)
69
23
Branches and tree tops
709
160
Stumps and roots
595
183
Total
1 372
366
*) low-quality wood that is not suitable for industrial processing
Broadleaved
23
137
175
335
Total
114
1 006
953
2 073
Table 42 Forest biomass energy potential, 1000 s-m3/year (ob), 2000, ROI
6.2.2 Defining sawmill residues potential (chips, sawdust, bark)
Overview of timber production and use in Ireland
Roundwood supply in 2000 on the whole island of Ireland was estimated at 3.24 million m3. Coillte’s share of the
total supply was about 84%, NIFS’s 10% and private suppliers accounted for about 6% 5). Roundwood supply is
forecasted to increase to 3.8 million m3 in 2003 and to about 4.5 million m3 by the year 2010.
According to the Timber Industry Development Group’s report, roundwood supply forecast to 2015 covering
timber production from Coillte, NIFS and the Private Estates would be as follows.
5
Report of the Timber Industry Development Group
61
5 000
4 500
4 000
ULSTER
3 500
3 000
LEINSTER
2 500
2 000
CONNAGHT
1 500
1 000
MUNSTER
500
0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Table 43 Roundwood production forecast by province, 1000 m3 (including Coillte, NIFS, and the Private Estates)
In 2000, 40% of the timber sold went to > 20cm (large saw logs) top log diameter, 35% to 14-20 cm (small saw
log) and 25% to 7-13 cm (pulpwood) diameter category. The province of Munster accounts for 36%, Connaugh
23%, Leinster 22% and Ulster 19% of the timber supplied within the Republic.
Logs with 7-13 cm diameter go primarily to the board mills whilst larger logs are used mainly in sawmills.
There are about 100, mainly family owned sawmills in Ireland, producing timber mainly for construction purposes and for pallet manufacturing. Sawn timber production in the year 2000 was about 880 000 m3 of sawn
goods, with round wood intake about 1.97 million m3. Respectively the residues production was about 1.08 million m3. Estimated roundwood intake to sawmills in 2003 was 2.4 million m3 and related output consisted of
about 1.095 million m3 of sawn goods and 1.305 million m3 of by-products. Production of sawn goods is estimated to increase to 1,141 million m3 by the year 2010.
All the biggest size sawmills are members of the Irish Timber Council (ITC). ITC’s sawmills process over 95% of
the appropriately sized saw logs in 13 processing plants. Their timber supply was sourced from Coillte (88%),
NIFS (8%) and private growers (4%).
62
Address
County
Killimer
Ballykilleen
Clare
Offaly
Longford
Offaly
1
2
3
4
Power Plants: (white)
Moneypoint
Edenderry
Lanesborough
Shannonbridge
1
2
3
4
5
Panel Board Mills: (blue)
Finsa Forest Products
Smartply Europe
Masonite Ireland
Spanboard Products
Wayerhaeuser Europe
Scarrif
Clare
Belview
Waterford
Carrick-on-ShannLeitrim
Coleraine
Derry
Clonmel
Tipperary
Sawmills: (red)
Balcas Timber Ltd.
Balcas Timber Ltd.
Balcas Timber Ltd.
Coolrain Sawmills Ltd.
Drenagh Sawmills Ltd.
Drenagh Sawmills Ltd.
ECC Teo
Glennon Bros Ltd.
Glennon Bros Ltd.
Laois Sawmills Ltd.
Murray Timber Products Ltd.
Murray Timber Products Ltd.
Nordale (Banagher Sawmills)
Palfab Ltd.
SFE (Grainger Sawmills Ltd.)
Woodfab Timber Ltd.
Crowe's
Diamond's
Irish Forest Prod (ceased)
O'Grady's
Wood Industries
Magherafelt
Enniskillen
Newtowngore
Coolrain
Limavady
Glenties
Corr na Móna
Fermoy
Longford
Portlaoise
Ballon
Ballygar
Banagher
Macroom
Enniskeane
Aughrim
Mohill
Coleraine
Mountrath
Hollyford
Rathdrum
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Biomass CHP -Plants (yellow)
Enniskeane
1 Graingers / SFE
Enniskillen
2 Balcas
Emyvale
3 Monopower Ltd.
Derry
Fermanagh
Leitrim
Laois
Derry
Donegal
Galway
Cork
Longford
Laois
Carlow
Galway
Offaly
Cork
Cork
Wicklow
Leitrim
Derry
Laois
Tipperary
Wicklow
Cork
Fermanagh
Monaghan
Figure 26 Map showing the geographical location of sawmills, panel board mills, power plants and biomass CHPplants
Estimated production in 2003, 1000 s-m3
Name
County
Balcas Timber Ltd.
Derry
Balcas Timber Ltd.
Fermanagh
Roundwood
Intake
Sawn
goods
Chips
Dust
Estimated production in 2010, 1000 s-m3
Roundwood
Intake
Bark
Sawn
goods
Chips
Dust
Bark
87
39
28
12
8
90
41
29
12
8
348
158
111
47
32
363
165
116
50
33
Balcas Timber Ltd.
Leitrim
47
21
15
6
4
49
22
16
7
4
Coolrain Sawmills Ltd.
Laois
61
28
19
8
6
64
29
20
9
6
Drenagh Sawmills Ltd.
Derry
87
39
28
12
8
90
41
29
12
8
ECC Teo
Galway
268
122
85
36
24
279
127
89
38
25
Glennon Bros Ltd.
Cork
178
81
57
24
16
186
84
59
25
17
Glennon Bros Ltd.
Longford
184
83
58
25
17
192
87
61
26
17
Laois Sawmills Ltd.
Laois
100
50
36
8
6
100
50
36
8
6
Murray Timber Products Ltd.
Carlow
121
55
38
16
11
126
57
40
17
11
Murray Timber Products Ltd.
Galway
268
122
85
36
24
279
127
89
38
25
Nordale (Banagher Sawmills)
Offaly
21
9
7
3
2
22
10
7
3
2
Palfab Ltd.
Cork
178
81
57
24
16
186
84
59
25
17
SFE (Grainger Sawmills Ltd.)
Cork
178
81
57
24
16
186
84
59
25
17
Woodfab Timber Ltd.
Wicklow
109
50
35
15
10
114
52
36
16
10
1
Crowe's
Leitrim
16
7
5
2
1
16
7
5
2
Diamond's
Derry
12
6
4
2
1
13
6
4
2
1
Irish Forest Prod (ceased)
Laois
20
9
6
3
2
21
10
7
3
2
1
O'Grady's
Tipperary
10
5
3
1
1
11
5
3
1
Wood Industries
Wicklow
19
9
6
3
2
20
9
6
3
2
61
28
19
8
6
64
29
20
9
6
2 400
1 095
768
322
215
2 500
1 141
800
335
224
Other Sawmills
TOTAL
Table 44 Estimated saw logs intake, sawn timber and related by-products production figures for 2003 and 2010.
63
Source: (i) Coford, Maximising the potential of wood use and (ii) Consultant’s own estimations
Total sawmill residues (chips, dust, bark) production (theoretical potential) in 2003 was 1.31 million m3 (2.29
TWhfuel) and estimated values for 2010 would be 1.36 million m3 (2.39 TWhfuel).
The biggest end user of the sawmill by-products is the panel board mill industry, which consumes annually
about 2 million m3 of raw wood. In 2003 the raw-wood intake to the board mills consisted of sawmill byproducts (51%) and pulpwood / recycled wood (49%). It is assumed that the capacity utilization rate and raw
material consumption of the panel board mills will remain at the same level in 2010 as in 2003.
Finsa Forest Products
Smartply Europe
Masonite Ireland
Spanboard Products
Wayerhaeuser Europe
Product
type
Location / county
Name
Scarrif / Clare
Belview / Waterford
Carrick-on-Shannon / Leitrim
Coleraine / Derry
Clonmel / Tipperary
Rawmaterial
input, tn
200 000
600 000
150 000
200 000
650 000
Chipboard
OSB
MDF
Chippoard
MDF
sawdust
Rawmaterial used
pulp- recycled
chips
wood
wood
50 %
50 %
100 %
100 %
70 %
30 %
80 %
20 %
Table 45. Panel board mills in Ireland
The geographical location of the panel board mills in operation can be seen in Figure 26.
In this study it is assumed that the sawmill industry will continue to be the principal raw material supplier for
panel board mills also in the future. After taking into account the demand for sawmill residue chips and sawdust
of the panel board mills, the excess sawmill by-products availability (technical potential) would be 296 000 m3
(528 GWhfuel) in 2003 and 350 000 m3 (624 GWhfuel) in 2010.
Theoretical
Technical
2003
2010
2003
Chips, 1000 m3
768
800
25
2010
57
TWhfuel
1,34
1,40
0,04
0,10
Dust, 1000 m3
322
335
56
69
TWhfuel
0,56
0,59
0,10
0,12
Bark, 1000 m3
215
224
215
224
TWhfuel
0,39
0,40
0,39
0,40
Total, 1000 m3
1 305
1 359
296
350
TWhfuel
2,29
2,39
0,53
0,62
Table 46 Theoretical and technical potential of sawmill by-products
There are also other uses of sawmill by-products like sawdust and bark to produce process heat to sawmills,
sawdust for animal bedding and bark for horticulture. Today sawmill owners will get higher income by selling
their by-products for horticultural uses and animal bedding rather than for energy production purposes. It is
also obvious that sawmills that have their own energy production (heat or combined heat and power) will use
their own sawmill waste materials as fuel. When taking these alternative uses of by-products into account, the
excess “realistic-technical” potential of by-products would be only about 50% of the technical potential expressed in Table 46.
64
Transportation costs
Biomass transportation costs are mainly affected by the energy density of the transported material, transportation distance, condition of the roads, type of transportation equipment used, fuel costs and the availability of
return cargo.
The gross weight of a truck in Ireland is limited to 45 tonnes. This means that the maximum weight of the cargo
is about 30 tonnes. Transportation of wood is usually limited by weight and not by volume.
Miles
Km
EUR/t
EUR/t, km
< 20
< 30
4.5
0.140
20-50
30-80
6.5
0.081
50-65
80-100
8.25
0.079
> 65
>100
9.5
.0.059
Table 47 Average transportation costs for sawmill by-product in 2003
Biomass transportation costs are assumed to rise by 20% by the year 2010.
The transportation costs of wood-based biomass have been estimated in energy units (EUR/MWhfuel) assuming
30-tonne payload and average transportation cost of EUR 0.081/tonne per one km.
W ood
Pellets
chi ps
Figure 27 Effect of energy density of biomass on the transportation volume
Distances
Road transportation distances (km) have been estimated from each sawmill to each power plant.
Supply curves
Biomass availability, in terms of quantity and fuel price, for each power plant under review can be presented in
a supply curve.
Wood fuel supply curves have been drawn to each power plant for the years 2003 and 2010 for each fuel type
presenting the theoretical and technical fuel potential. The x-axis represents the cumulative fuel energy volume
(GWh) and y-axis the price level (EUR/MWh) of the fuel available. Price levels have been calculated as follows:
Gate fee (EUR/MWh, at the sawmill) + (transportation cost, EUR/MWh * transportation distance, km)
The gate fee used in this study for sawmill by-products for the year 2003 are EUR 18/t (EUR 11.4/MWh) for chips,
EUR 5.8/t (EUR 3.6/MWh) for sawdust and EUR 11.7/t (EUR 7.4/MWh) for bark. Gate fees are expected to rise by
20% by the year 2010.
65
Moneypoint, technical potential, 2003
€/MWh fuel
€/MWh fuel
Moneypoint, theoretical potential, 2003
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
Chips
Dust
Bark
0
200
400
600
800
1 000
1 200
1 400
1 600
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
1 800
Chips
Dust
Bark
0
50
100
150
GWh fuel
€/MWh fuel
€/MWh fuel
Dust
Bark
200
400
600
300
350
400
450
500
Moneypoint, technical potential, 2010
Chips
0
250
GWh fuel
Moneypoint, theoretical potential, 2010
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
200
800 1 000 1 200 1 400 1 600 1 800
GWh fuel
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
Chips
Dust
Bark
0
50
100
150
200
250 300
GWh fuel
Figure 28 Availability of sawmill by-products to Moneypoint power plant, 2003 and 2010
66
350
400
450
500
Edenderry, technical potential, 2003
24
23
23
22
22
21
21
20
20
19
19
18
18
17
17
16
16
€/MWh fuel
€/MWh fuel
Edenderry, theoretical potential, 2003
24
15
14
13
15
14
13
12
12
11
11
10
10
9
9
Chips
Dust
Bark
8
7
6
8
Chips
Dust
Bark
7
6
5
5
0
200
400
600
800
GWh fuel
1 000
1 200
1 400
0
50
€/MWh fuel
€/MWh fuel
Chips
Dust
Bark
0
200
400
600
800
GWh fuel
1 000
150
200
GWh fuel
250
300
350
400
Edenderry, technical potential, 2010
Edenderry, theoretical potential, 2010
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
100
1 200
1 400
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
Chips
Dust
Bark
0
50
100
150
200
GWh fuel
250
Figure 29 Availability of sawmill by-products to Edenderry power plant, 2003 and 2010
67
300
350
400
West Offaly Power, technical potential, 2003
€/MWh fuel
€/MWh fuel
West Offaly Power, theoretical potential, 2003
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
Chips
Dust
Bark
0
200
400
600
800
GWh fuel
1 000
1 200
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
Chips
Dust
Bark
0
1 400
Chips
Dust
Bark
0
200
400
600
800
1 000
1 200
100
150
200
GWh fuel
250
300
350
400
West Offaly Power, technical potential, 2010
€/MWh fuel
€/MWh fuel
West Offaly Power, theoretical potential, 2010
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
50
1 400
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
Chips
Dust
Bark
0
50
100
150
200
GWh fuel
GWh fuel
Figure 30 Availability of sawmill by-products to West Offaly Power, 2003 and 2010
68
250
300
350
400
Lough Ree, technical potential, 2003
€/MWh fuel
€/MWh fuel
Lough Ree, theretical potential, 2003
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
Chips
Dust
Bark
0
200
400
600
800
GWh fuel
1 000
1 200
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
1 400
Chips
Dust
Bark
0
50
Chips
Dust
Bark
0
200
400
600
800
1 000
150
200
GWh fuel
250
300
350
400
Lough Ree Power, technical potential, 2010
€/MWh fuel
€/MWh fuel
Lough Ree Power, theoretical potential, 2010
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
100
1 200
1 400
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
Chips
Dust
Bark
0
GWh fuel
50
100
150
200
250
GWh fuel
300
350
Figure 31 Availability of sawmill by-products to Lough Ree Power, 2003 and 2010
6.2.3 Defining pulpwood (small-diameter roundwood) potential
Pulpwood has been defined as timber with a top diameter of 7 to 14 cm. However, small sawlog may be “downgraded” to pulp on the basis of poor quality.
Potential availability of pulpwood for energy production purposes has been analysed in the Maximising the
Potential of Wood Use for Energy Generation in Ireland, 2002 and in the Timber Industry Development Group
report, 2001. Produced from data in these reports the following estimates of excess volume for pulpwood can
be drawn.
69
400
Unit
2000
2003
2010
Total pulpwood (theoretical potential)
1000 m3
1 266
1 343
1 773
Total pulpwood (theoretical potential)
GWh
2 005
2 128
2 808
Overall excess of pulpwood (technical potential)
1000 m3
186
146
459
Overall excess of pulpwood (technical potential)
GWh
295
231
728
Table 48 Estimate of volumes of excess pulpwood, 2000, 2003 and 2010
The technical potential is the amount of pulpwood that is left over after panel board mill roundwood intake as
pulp as well as raw material needs for stakes production have been taken into account.
Location
In this study it is assumed that pulpwood has been distributed among the counties in the same proportion as
the estimated roundwood production will take place.
2003
1000 m3
Antrim
Armagh
Carlow
Cavan
Clare
Cork
Derry
Donegal
Down
Dublin
Fermanagh
Galway
Kerry
Kildare
Kilkenny
Laois
Leitrim
Limerick
Longford
Louth
Mayo
Meath
Monaghan
Offaly
Roscommon
Sligo
Tipperary
Tyrone
Waterford
Westmeath
Wexford
Wicklow
Total
77
20
48
69
106
475
56
296
39
12
73
301
130
45
80
180
98
88
11
32
342
28
56
76
82
67
194
137
227
23
90
249
3 811
%
2
1
1
2
3
12
1
8
1
0
2
8
3
1
2
5
3
2
0
1
9
1
1
2
2
2
5
4
6
1
2
7
100
2010
1000 m3
96
25
45
188
204
442
70
268
48
21
91
453
153
56
100
140
156
106
58
20
231
40
34
82
68
172
268
171
200
51
53
331
4 441
%
2
1
1
4
5
10
2
6
1
0
2
10
3
1
2
3
4
2
1
0
5
1
1
2
2
4
6
4
5
1
1
7
100
Table 49 Roundwood production in the island of Ireland, 1000 m3
The transportation distances have been calculated from the geographical centre of every county to each power
plant.
70
Fuel production costs
Fuel production costs used are:
•
•
•
•
Pulpwood stumpage price: EUR 5/t (EUR 2.8/MWh) in 2003 and 2010
Pulpwood compilation and forest transportation costs: EUR 5/m3 in 2003 and EUR 4/m3 in 2010
Road transportation cost: EUR 0.081/t per km in 2003 and EUR 0.097/t in 2010
Chipping cost: EUR 7.65/t in 2003 and EUR 5/t in 2010
Supply curves
Moneypoint / pulpwood
30
29
28
27
26
25
24
23
€/MWh fuel
22
21
20
19
18
17
16
Theoretical, 2003
15
Technical, 2003
14
13
Theoretical, 2010
12
Technical, 2010
11
10
0
400
800
1200
1600
2000
2400
2800
GWh fuel
Figure 32 Availability of pulpwood to Moneypoint Power Plant, 2003 and 2010
71
Edenderry / pulpwood
23
22
21
20
19
€/MWh fuel
18
17
16
15
14
13
Theoretical, 2003
12
Technical, 2003
11
Theoretical, 2010
Technical, 2010
10
9
0
400
800
1200
1600
2000
2400
2800
GWh fuel
Figure 33 Availability of pulpwood to Edenderry Power Plant, 2003 and 2010
West Offaly / pulpwood
23
22
21
20
19
€/MWh fuel
18
17
16
15
14
Theoretical, 2003
13
Technical, 2003
12
Theoretical, 2010
11
Technical, 2010
10
0
400
800
1200
1600
2000
2400
2800
GWh fuel
Figure 34 Availability of pulpwood to West Offaly Power Plant, 2003 and 2010
72
Lough Ree / pulpwood
23
22
21
20
19
18
€/MWh fuel
17
16
15
14
13
12
Theoretical, 2003
11
Technical, 2003
10
Theoretical, 2010
Technical, 2010
9
8
0
400
800
1200
1600
2000
2400
2800
GWh fuel
Figure 35 Availability of pulpwood to Lough Ree Power Plant, 2003 and 2010
6.2.4 Defining forest residues potential
The theoretical and technical availability of forest residues has been studied in detail in the COFORD study
“Maximising the Potential of Wood Use for energy Generation in Ireland, 2001”. The following text is a direct
citation of the COFORD study.
“Binggeli et al (2001) have estimated the annual potential resource of forest residues in Ireland based on timber
harvesting and roundwood production projections from Coillte, COFORD and the Northern Ireland Forest Service. No detailed estimates were available for projected production from private forest plantations in Northern
Ireland.
An initial assessment of production of total forest residues was calculated by applying a factor of 0.3 on to the
timber production figures of Coillte, COFORD and the Northern Ireland Forest Service. This methodology was
based on that adopted by the UK Forestry Contractors Association (Hudson, 1997) and follows their definition of
forest residues as including ‘all above ground material removed from marketable trees and including tops,
branches, foliage and un-marketable stem pieces from in-forest conifer harvesting operations’. It also takes account of residuals, defined as ’small, dead and fallen trees’.
The influence of soil types and, perhaps more importantly, the reluctance of the harvesting managers to stop
using brash mats mean that it is unlikely that all the forest residues present will be made available in a noncontaminated form (even though the procedure of windrowing forest residues costs between 89 and 254 euros
per hectare (average 149 euros) and reduces re-planting density and evenness). A more realistic model for early
exploitation of clean forestry residues for heat and power should assume that only the top portion of the tree
would be made available. These tops can be handled more efficiently using existing forestry equipment, particularly if they have been passed through a harvesting head and are partially cleaned of twigs and needles. The
resulting chip will also be more uniform, with less small material and a more rounded form. Another advantage
of using this material is that it can be harvested from all spruce plantations, almost regardless of the soil types or
terrain conditions. An estimate of the initial amount of forest residues that is likely to be made available for fuel
can be made by applying a factor of 0.7 (to account for pine and minor conifer plantations, whose brash mats
73
are considered much weaker than spruce) and then applying a second factor of 0.09 to the roundwood production targets. This model will be considered the most appropriate for the early exploitation of forest residues.”
1 400
1 200
1000 m3
1 000
800
Theoretical potential
Technical potential
600
400
200
0
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Figure 36 Forest residue production in Ireland 2001 - 2010
3
1000 m
GWhfuel
Theoretical
2003
2010
Technical
2003
2010
1 143
1 810
240
380
280
443
1 333
2 111
Table 50 Forest residue potential in Ireland 2003, 2010
Location
In this study it is assumed the pulpwood has been distributed among the counties in the same proportion as
the estimated roundwood production will take place as presented in the table 49.
Fuel production costs
The transportation distances have been calculated from the geographical center of every country to each
power plant.
Fuel production costs used are:
Forest residue stumpage price: EUR 0/t
Forest residue compilation and off-road transportation cost: EUR 6.9/MWh (EUR 11/m3) in 2003 and
EUR 5.4/MWh (EUR 8.5/m3) in 2010
Road transportation costs: EUR 0.081/t per km in 2003 and EUR 0.097/t in 2010
Chipping cost: EUR 4.3/MWh (EUR 7.65/t) in 2003 and EUR 2.8/MWh (EUR 5/t) in 2010
Logging residues have not been compiled and transported away from the forest so far in Ireland. This means
that logging residues production costs are not known. Production costs are totally dependent on the cost effectiveness of the chosen production systems.
74
In this study it is assumed that logging residues (as well as pulpwood) are chipped prior to entering the power
plant. In practice this means that comminution will take place in the terrain (in forest at the source) or at landing
(at the road-side). The logging residue costs estimated in this study for Ireland (EUR 11.3/MWh, excluding roadtransportation, overhead and VAT) are about 40% higher than the current logging residue production costs in
Finland (EUR 6.8/MWh). However, production costs are estimated to decrease to the level of about EUR
8.2/MWh by the year 2010 after finding the most cost-effective production technologies, systems and entrepreneurship structure.
Finnish experiences of the large-scale production systems of forest chips are described in appendix 5.
Supply curves
Moneypoint / forest residues
30
29
28
27
26
25
24
23
€/MWh fuel
22
21
20
19
18
17
16
15
Theoretical, 2003
14
Technical, 2003
13
Theoretical, 2010
12
Technical, 2010
11
10
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
GWh fuel
Figure 37 Availability of forest residues to Moneypoint Power Plant, 2003 and 2010
75
EDENDERRY / forest residues
24
23
22
21
20
19
€/MWh fuel
18
17
16
15
14
Theoretical, 2003
13
Technical, 2003
12
Theoretical, 2010
11
Technical, 2010
10
9
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
GWh fuel
Figure 38 Availability of forest residues to Edenderry Power Plant, 2003 and 2010
WEST OFFALY / forest residues
24
23
22
21
20
€/MWh fuel
19
18
17
16
15
14
Theoretical, 2003
13
Technical, 2003
Theoretical, 2010
12
Technical, 2010
11
10
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
GWh fuel
Figure 39 Availability of forest residues to West Offaly Power Plant, 2003 and 2010
76
LOUGH REE / forest residues
24
23
22
21
20
19
€/MWh fuel
18
17
16
15
14
13
Theoretical, 2003
12
Technical, 2003
11
Theoretical, 2010
10
Technical, 2010
9
8
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
GWh fuel
Figure 40 Availability of forest residues to Lough Ree Power Plant, 2003 and 2010
6.2.5 Defining short rotation coppice plantations (willow) potential
Energy crops are any biomass material grown principally for the purpose of converting into fuel for power generation, heat or transport. Technically this could include a wide range of material. However, for the purposes of
this analysis short rotation coppice (SRC) willow was chosen because willow has been cultivated for energy production in many European countries and in the USA and Canada. Willow is an agricultural crop, which means
that it is possible to stop growing willow and change to another crop if so desired.
In order to be able to estimate willow resource potential in Ireland it is necessary to understand the common
agricultural policy (CAP) and its anticipated development trends. Agricultural policy in Ireland will change under
CAP reform, and so any energy coppice plantation assumptions based on the existing situation will be invalid.
Ireland has opted for full decoupling under CAP reform, which comes into effect in January 2005. 80% of agricultural area in Ireland is currently devoted to grass (silage, hay & pasture), 11% to rough grazing, with the remaining 9% to crop production. From the IENICA report from the Republic of Ireland (EU 5th Framework Programme), the total set-aside land in 1999 was 30,400 hectares. Farmers will probably be required to maintain
set-aside land under the CAP reform. However, in this study the theoretical willow potential is based on the assumption that this set-aside land would be devoted to short rotation coppice production.
Both the theoretical and practical (technical) resource for 2003 is practically zero. There are some farmers in
Northern Ireland who are growing their own coppice to gasify and fire a 100 - 200 kWe gas engine at the farm.
Theoretical resource potential for 2010 would be 669 000 t (1,155 GWh) from 30,400 ha planting area assuming
22 t/ha output (10 t/ha, Oven Dry Tonne) and a calorific value of 1.73 MWh/t (60% moisture, 2 % ash).
Even if all set-aside land was planted with energy crops, this would only amount to 0.7% of total agricultural
area. It therefore seems unlikely that set-aside land alone will provide significant energy crop production potential. Regarding job creation, energy crop production is likely to be a displacement activity within agriculture as
farmers choose to switch from food crop production if the economics are right. It is therefore unlikely to give
rise to significant additional job creation.
77
Annex 3 of the Consultation Document on Options for Future Renewable Energy Policy, Targets and Programmes, recently published by the Department of Communications, Marine & Natural Resources, has estimated the technical resource potential to be 57,000 t (99 GWh) assuming a production area of 2,600 ha in the
year 2010. This production area can be considered realistic in 2010, because there is a 4 year lead time before
the plantations can be commercially harvested for the first time, which effectively means that all the crops
would need to be planted in the next 1-2 years and because currently there is no support policy in place in Ireland for energy crops.
Production costs
Production costs involved in producing fuel from energy crops is derived from the data presented in the study
“An Assessment of Changes to the Renewables Obligation Rules Relating to Co-firing in UK, A report to Dti, August 2003.
Final costs of the SRC-based fuel depend on the soil preparation costs, crop planting costs, maintenance, weed
and pest control, harvesting and chipping costs and transportation costs. In this study it is assumed that the
same cost level that is prevailing in the UK would also apply in Ireland.
The estimated fuel production costs would be EUR 23.6/MWh (EUR 40.8/t) including establishment, maintenance and harvesting costs. Establishment costs have been divided equally to the estimated lifetime (20 years)
of the plantation. The production cost can be considered rather high, and strong incentives should be given to
the farmers so that SRC plantations would become an option for the farmers. It would also be important that
possible growers should be situated as close to the power plant as possible in order to minimize the transportation costs.
In this study it is assumed that the average transportation distance would be 50 km and the transportation cost
EUR 0.056/MWh per one km. This means that the total cost of willow chips delivered to the power plant would
be:
Base value:
Transportation
Total
EUR 23.6/MWh
EUR 2.8/MWh
EUR 26.4/MWh
6.2.6 Overseas trading of biofuels (wood pellets)
General about overseas trading of biofuels
The only biomass based fuel that is commercially traded overseas, is wood pellets. The overseas trading of refined biomass is understandable because the transportation cost of traditional biomass is very high due to low
calorific value per volume. In addition, because of the high moisture content of the biomass, the cargo would
soon start to decompose during the long sea transportation. The heterogeneous and wet biomass would also
cause problems at the power plant premises, related to storing, handling (conveying) and further processing
(drying, chipping, moulding) to suitable fuels. Pellets are suitable for trading because of high calorific value per
volume (3 times higher than forest chips). As homogenous material they are suitable for pneumatic unloading.
Pellets can be crushed and used also by co-firing with coal in pulverised combustion boilers, and the security of
supply of pellets from overseas is good due to increasing production quantities in several countries.
Some small-scale "biomass for energy" trial shipments of low quality round wood logs of low calorific value per
volume have been made during the past years, probably from South America and Africa to Europe. These shipments have been implemented by private enterprises, which means that no accurate public information is
available. However, based on the experience of some of the big biomass energy users, the overseas trading of
large quantities of unrefined biomass is not feasible.
Wood pellet markets
Production of the wood-based-pellets in the world was estimated to about 2.5 million tonnes in 2002. The biggest pellet producing areas were Northern Europe (mainly Sweden, Finland, Denmark and recently also Austria
78
and Germany) accounting for about 55% of the total production, and North America (USA, Canada) with about
40% market share. Also the Baltic Countries are important pellet producers, especially Latvia and Estonia. In addition, some new wood-based-pellet production capacity has been installed in countries with an abundance of
cheap and unutilised raw-material resources like Russia, several countries in South and Central America and
Asia. Almost all pellets produced in Russia, the Baltic Countries, and South and Central America are exported to
Europe. In addition, more than 100,000 tonnes of pellets are exported from Canada to Europe.
The UK and Ireland have plans to use pellets both in large-scale energy production and in households, but so far
their own pellet production has been very modest or non-existent.
Globally the EU is pioneering the pellet market development driven by GHG emission reduction targets and EU
energy policies aiming at increased energy independence and the role of renewable energy sources (action
plan to double the share of renewable energy sources in EU energy balance between 1995 and 2010 from 6 to
12%). The main driver to increase production and consumption of pellets is the taxation of fuels and energy
production or consumption within many EU countries that favour renewable energy with low GHG emissions.
In the USA the pellet market was already created in the 1970s as a response to the energy crises. The size of the
US market is relatively small compared to Europe. Also, the US pellet market has not grown as rapidly as in the
EU. The main reason is that the US energy policy does not provide similar support and incentives for development of renewable energy sources as the EU energy policy.
The most important markets for industrial pellets are Sweden and Denmark. Both countries have existing coalfired heating/power plants that already import pellets in large-scale overseas shipments. In 2001 the woodpellet imports to Sweden were about 150 000 tonnes/year and to Denmark about 110 000 tonnes/year. Most of
the pellets imported to these countries originated from other European countries, but regular overseas shipments occur e.g. from Canada. It is anticipated that the pellet imports to Sweden and Denmark will almost double by the year 2010 compared to 2001.
Cost-insurance-freight (CIF) prices for overseas traded wood pellets in 2003 were EUR 100-110/tonne (EUR 2123/MWh, EUR 5.8-6.4/GJ) in Europe. Import prices have increased by some 3-5% / year in recent years. The
maximum ship-load size in Sweden will be more restricted (5,000-10,000 t/ship) than in Denmark. This will have
some impact on delivery costs (USD 5-10 /t), which could be made up by the CIF price difference between
Denmark and Sweden. (Note: overseas freight prices started to increase rapidly as from the beginning of 2004
due to heavy demand for metal in China resulting in fully booked vessel capacity)
The demand for wood pellets both in industrial applications as well as in domestic use are increasing especially
in the EU countries. In the future there will also be a shortage of pellet raw material in the traditional pellet producing countries. This means that the pellet prices can be expected to rise in the future. On the other hand it is
expected that the low-cost structure countries (e.g. Honduras, Venezuela, Brazil and Russia) will start to produce
pellets or increase existing production for solely export purposes. This would help to smooth out the price development of imported pellets.
Costs
The only cost applied to wood pellets at Moneypoint is the purchase price of EUR 100-110/t, which includes
unloading of the cargo. At the Edenderry, West Offaly and Lough Ree power plants the wood pellet cost comprises the purchase price and road transportation cost from Dublin to the power plant.
International prices for wood pellets are anticipated to remain at the same level as today. Each wood pellet producer in the world can usually supply about 100-250 GWh pellets per year. The purchase price of the pellets can
probably be lowered by making long-term fuel purchase agreements.
79
Supply curves
Wood pellets, 2003
26
25
€/MWh fuel
24
23
22
21
Moneypoint
Edenderry
West Offaly
Lough Ree
20
19
0
100
200
300
400
500
600
700
800
900 1000 1100
GWh fuel
Figure 41 Availability of wood pellets in 2003
Wood pellets, 2010
26
25
€/MWh fuel
24
23
22
21
Moneypoint
Edenderry
West Offaly
Lough Ree
20
19
0
100
200
300
400
500
600
700
800
900
1000 1100
GWh fuel
Figure 42 Availability of wood pellets in 2010
80
6.3
Availability of straw
The total area of agricultural land under crops, fruit, horticulture and grass in 2002 was about 4.8 million hectares on the Island of Ireland. Crops, fruit and horticulture accounted for 10% of that area, silage for 23%, hay for
4%, pasture for 52% and rough grazing for 11%. The best farmlands are found in the east and southeast.
The amount of the production of straw depends in the first instance on agronomy, i.e., the science of cultivation
of land, soil management, and crop production. The annual straw production is influenced by the framework
stipulated by the EU agricultural policies, including developments in cereal prices, the fallow of land etc. The
straw quality and the amount of straw that can be gathered in are also influenced by the weather during growing and harvest.
Straw is a by-product resulting from the growing of commercial crops, primarily cereal grain. Total area under
cereal grains (wheat, barley, oats) cultivation in the ROI was 297,500 hectares and 38,000 ha in the NI in 2002.
Grain yield per hectare was 8.4 t of wheat, 7.1 t of oats and 5.5 t of barley.
Cereal production has been relatively steady during the past couple of years. However, it is expected that total
area under cereal production will decline by about 7% by the year 2012. This would mean that straw production
will drop in the coming years by about 0.9% per year.
The number of cereal growers has fallen from about 100,000 in 1975 to the current number, which is about
15,000. This trend is to continue and it has been estimated that there may be 1,000–1,500 full-time and 5,000–
6,000 part-time tillage farmers in Ireland within a 10 year time frame.
Total cereal straw production potential (theoretical potential) would be about 1,4 Mt (5.3 TWh fuel) if 4,8 t of
straw per hectare would be collected up from all areas under cereal cultivation (297,500 ha in 2002). Theoretical
potential would be 1.34 Mt (5 TWh) from about 279,000 ha in the year 2010.
The greater part of the straw produced in Ireland is used in agriculture’s own production, i.e. as animal bedding
material, animal feed supplement, mushroom compost component and as a soil structure / fertilizer improvement material. The excess straw that would be left unutilized after traditional uses would possibly be available
for energy production purposes. Realistic straw potential (technical potential) for energy production purposes
has been estimated assuming straw collection from areas covering 5% in the year 2003 and 8% in 2010 from the
total cereal cultivation area. This would mean current technical availability of 71,000 t (265 GWh fuel) of straw in
2003 and respectively 107,000 t (400 GWh) of straw in 2010.
Straw production costs
Straw production quantities have been divided between the counties in the proportion as cereal is cultivated in
the Counties.
A base value for straw can be assumed considering its intrinsic worth as a fertilizer and as a soil structure improver. If a straw price of EUR 86.45/ha (= EUR 18/t, EUR 4.8/MWh)) cannot be obtained for straw on the ledge
i.e. cut and un-baled, it is more cost effective for farmers to return this straw to the ground. The same basic
value has been used for the years 2003 and 2010.
Straw for energy production purposes needs to be collected and baled for efficient transportation. Baling costs
of straw to “Large Squares” (weight 550–620 kg/bale) vary from EUR 52 to EUR 65/t. In this study a baling cost of
EUR 55/t (EUR 16.4/MWh) has been used for the year 2003 and EUR 40/t (EUR 11.9/MWh) for the year 2010.
81
Transportation costs
Transportation of straw is limited by volume and not by weight. A standard trailer could carry a payload of
about 9 or 10 t (33–37 MWh). In this study transportation costs of EUR 0.076/MWh per one km in 2003 and EUR
0.091/t per one km in 2010 have been used.
Supply curves
Moneypoint / straw
52
50
48
46
44
42
€/MWh fuel
40
38
36
34
32
30
28
Theoretical, 2003
26
Technical, 2003
24
Theoretical, 2010
22
Technical, 2010
20
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
GWh fuel
Figure 43 Availability of straw to Moneypoint Power Plant in 2003 and 2010
82
Edenderry / straw
42
40
38
36
€/MWh fuel
34
32
30
28
26
Theoretical, 2003
24
Technical, 2003
22
Theoretical, 2010
20
Technical, 2010
18
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
GWh fuel
Figure 44 Availability of straw to Edenderry Power Plant in 2003 and 2010
West Offaly / straw
42
40
38
36
€/MWh fuel
34
32
30
28
26
Theoretical, 2003
24
Technical, 2003
22
Theoretical, 2010
20
Technical, 2010
18
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
GWh fuel
Figure 45 Availability of straw to West Offaly Power Plant in 2003 and 2010
83
Lough Ree / straw
41
39
37
35
€/MWh fuel
33
31
29
27
25
Theoretical, 2003
23
Technical, 2003
21
Theoretical, 2010
19
Technical, 2010
17
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
GWh fuel
Figure 46 Availability of straw to Lough Ree Power Plant in 2003 and 2010
6.4
Availability of chicken litter
According to the Central Statistics Office, the data for 2002 shows that there were 12.7 million poultry (11.6 million chickens) in the ROI. In 2002 the total number of poultry in Northern Ireland was 16.9 million birds, of which
about 11 million were chickens. According to the Consultant’s estimation, there could be 4,000-9,000 chicken
farmers (average farm size: 2,500–4,500 birds per poultry farm) on the whole Island of Ireland.
Chicken production is very concentrated in the Counties of Antrim, Monaghan and Tyrone, which alone produce about 60% of the total chicken litter in Ireland. Distribution of chickens by county and related litter production have been estimated in the following table assuming that one broiler chicken produces about 20 g of
litter per day.
84
Chickens
Antrim
Armagh
Carlow
Cavan
Clare
Cork
Derry
Donegal
Down
Dublin
Fermanagh
Galway
Kerry
Kildare
Kilkenny
Laois
Leitrim
Limerick
Longford
Louth
Mayo
Meath
Monaghan
Offaly
Roscommon
Sligo
Tipperary
Tyrone
Waterford
Westmeath
Wexford
Wicklow
Total
1000 pcs
4 850
981
14
616
8
792
607
33
1 517
13
487
129
177
13
12
14
30
1 740
19
19
297
318
4 812
5
4
7
17
4 048
857
26
111
30
22 600
Theoretical Technical
t litter
29 487
5 963
83
3 745
48
4 815
3 693
201
9 224
76
2 964
783
1 079
76
70
83
184
10 577
114
114
1 803
1 932
29 258
32
23
42
104
24 614
5 208
158
676
181
137 408
Theoretical Technical
t litter
GWh litter GWh litter
7511
73
19
1519
15
4
21
0
0
954
9
2
12
0
0
1226
12
3
941
9
2
51
0
0
2349
23
6
19
0
0
755
7
2
199
2
0
275
3
1
19
0
0
18
0
0
21
0
0
47
0
0
2694
26
7
29
0
0
29
0
0
459
4
1
492
5
1
7452
72
18
8
0
0
6
0
0
11
0
0
27
0
0
6269
61
15
1327
13
3
40
0
0
172
2
0
46
0
0
35 000
340
86
Table 51. Chicken litter potential for 2002 (t, GWh)
Theoretical litter resource potential is estimated to be 137,000 t (340 GWh) and technical potential 35,000 t (86
GWh) in 2002. These potentials are anticipated to be the same in the year 2010.
There are currently only two principal outlets for chicken litter namely the mushroom industry (constituent of
mushroom compost) and agriculture (land spreading). It is estimated that 60,000-100,000 t of broiler litter are
used by the mushroom industry and 50,000-80,000 t of poultry litter are land-spread in Ireland every year.
The feasible / accessible poultry litter resource is produced by a total of 950 commercial poultry production
units. In the “Dry Agricultural Residues Resource Study, 2003” the practical poultry litter resource in Ireland has
been estimated to be 25,000–40,000 t per annum.
Production costs
Base value: EUR 10/tonne (EUR 2.7/MWh).
Transportation cost: EUR 0.033 /MWh in 2003 and EUR 0.039/MWh in 2010.
All analyses are based on the net calorific value in dry matter of 15 MJ/kg (4.17 MWh/t) and in fresh matter of 8.9
MJ/kg (2.47 MWh/t).
85
Demand Curves
Moneypoint / litter
18
17
16
15
14
€/MWh fuel
13
12
11
10
9
8
Theoretical, 2003
7
Technical, 2003
6
Theoretical, 2010
5
Technical, 2010
4
0
50
100
150
200
250
300
350
GWh fuel
Figure 47 Availability of litter to Moneypoint Power Plant in 2003 and 2010
Edenderry / litter
13
12
11
€/MWh fuel
10
9
8
7
Theoretical, 2003
6
Technical, 2003
Theoretical, 2010
5
Technical, 2010
4
0
50
100
150
200
250
300
350
GWh fuel
Figure 48 Availability of litter to Edenderry Power Plant in 2003 and 2010
86
West Offaly / litter
14
13
12
11
€/MWh fuel
10
9
8
7
Theoretical, 2003
Technical, 2003
6
Theoretical, 2010
5
Technical, 2010
4
0
50
100
150
200
250
300
350
GWh fuel
Figure 49 Availability of litter to West Offaly Power Plant in 2003 and 2010
Lough Ree / litter
14
13
12
11
€/MWh fuel
10
9
8
7
Theoretical, 2003
Technical, 2003
6
Theoretical, 2010
5
Technical, 2010
4
0
50
100
150
200
250
300
350
GWh fuel
Figure 50 Availability of litter to Lough Ree Power Plant in 2003 and 2010
87
6.5
Availability of spent mushroom compost
SMC is a low value waste product of the mushroom growing industry. The value of the industry has been growing consistently over the last twenty years. The number of growers has been decreasing from the 566 growers
in the 1995 to some 365 in 2002.
Mushroom compost is produced by seven major producers located predominantly in the border counties of
Cavan and Monaghan, and one producer each in Kildare and Wexford. Principal outlet of SMC is land-spreading,
which is a good provider of both potassium and phosphates and can improve the soil structure. Currently about
80% of SMC is land-spread by mushroom farmers.
Total theoretical SMC production was 290 000 t (199 GWh) in 2002. It is anticipated that production figures will
remain at the same level also in the near future.
The technical resource potential would be that fraction of the theoretical resource that could be available for
alternative uses. This fraction will involve a cost of disposal for the mushroom growers. Where mushroom producers have the land capacity to land-spread the SMC they produce, there is no cost associated with its production and disposal and so there would be no reason for them to send their SMC elsewhere while it remains a
negative value product. In this study it is assumed that the cost of removal of SMC for mushroom growers is 4 IR
£ per tonne (EUR ~5 /tonne). Technical, accessible SMC resource potential has been estimated to be 92,000 t (63
GWh).
88
Antrim
Armagh
Carlow
Cavan
Clare
Cork
Derry
Donegal
Down
Dublin
Fermanagh
Galway
Kerry
Kildare
Kilkenny
Laois
Leitrim
Limerick
Longford
Louth
Mayo
Meath
Monaghan
Offaly
Roscommo
Sligo
Tipperary
Tyrone
Waterford
Westmeath
Wexford
Wicklow
Theoretical
tonnes
1 306
22 856
3 222
32 162
4 317
1 810
1 633
15 227
5 712
2 263
1 306
4 982
447
14 030
1 064
500
1 698
1 682
9 640
3 872
20 442
8 559
46 363
3 401
14 601
2 211
22 753
19 591
246
7 787
9 226
4 328
289 236
Technical
tonnes
16 325
20 111
1 961
2 538
805
8 564
42 176
92 480
Table 52 Theoretical and technical SMC resource potential in 2003, tonnes (predicted to remain the same
in 2010)
89
Supply curves
Moneypoint / SMC
40
38
36
34
32
30
28
26
€/MWh
24
22
20
18
16
14
12
10
Theoretical, 2003-2010
8
6
Technical, 2003-2010
4
2
0
0
50
100
150
200
250
GWh
Figure 51 Availability of SMC to Moneypoint Power Plant in 2003 and 2010
Edenderry / SMC
24
22
20
18
16
€/MWh
14
12
10
8
6
Theoretical, 2003-2010
4
Technical, 2003-2010
2
0
0
50
100
150
200
250
GWh
Figure 52 Availability of SMC to Edenderry Power Plant in 2003 and 2010
90
West Offaly / SMC
26
24
22
20
18
€/MWh
16
14
12
10
8
6
Theoretical, 2003-2010
4
Technical, 2003-2010
2
0
0
50
100
150
200
250
GWh
Figure 53 Availability of SMC to West Offaly Power Plant in 2003 and 2010
€/MWh
Lough Ree / SMC
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Theoretical, 2003-2010
Technical, 2003-2010
0
50
100
150
200
250
GWh
Figure 54 Availability of SMC to Lough Ree Power Plant in 2003 and 2010
91
Availability of other biomass types
6.6
MBM
Meat and bone meal (MBM) is not a well known fuel in heat production in many countries. It is rather homogenous regarding the particle size distribution as well as chemical and physical properties.
Each year, the meat sector in Ireland generates some 550,000 tonnes of animal by-product for rendering, in
compliance with EU veterinary rules, into about 150,000 tonnes of MBM at 8 Department of Agriculture and
Food approved rendering plants. This can be considered to be the theoretical resource potential of MBM totalling 150,000 t (613 GWh) in 2003. Assuming that the MBM production trend is the same as with tallow the MBM
production quantity in 2010 will be some 135,000 tonnes (552 GWh).
At present, all MBM is directed for incineration. In this study it is assumed that 50% of MBM produced would be
technically available for co-firing purposes for the power plants under review in this study. This would mean
production figures of 75,000 t (306 GWh) for 2003 and 68,000 t (276 GWh) for 2010.
In this study MBM is split between producers using the same proportions as tallow production is split up.
Plant
2003 Theoretical
2003 Technical
tonnes
tonnes
GWh
GWh
2010 Theoretical
tonnes
GWh
2010 Technical
tonnes
GWh
Premier
19 822
81
9 911
40
17 840
73
8 986
37
Monery
17 344
71
8 672
35
15 610
64
7 863
32
College
14 867
61
7 433
30
13 380
55
6 740
28
Waterford
14 485
59
7 243
30
13 037
53
6 567
27
Dublin
39 644
162
19 822
81
35 680
146
17 972
73
Slaney
9 149
37
4 574
19
8 234
34
4 147
17
Western
14 867
61
7 433
30
13 380
55
6 740
28
Munster
Total
19 822
81
9 911
40
17 840
73
8 986
37
150 000
613
75 000
306
135 000
552
68 000
278
Table 53. Theoretical and technical production estimates for MBM
MBM production costs
A base price for MBM that the rendering plants would get when selling MBM is not known. A base value of EUR
5/MWh (EUR 20/tonne) ex factory has been used in this study.
Transportation costs used to define the supply curve are EUR 0.020/MWh per km for 2003 and EUR 0.024/MWh
per one km for 2010.
92
Supply curves
Moneypoint / MBM
13
12
€/MWh
11
10
9
Theoretical, 2003
Technical, 2003
8
Theoretical, 2010
Technical, 2010
7
0
100
200
300
400
500
600
700
GWh
Figure 55 Availability of MBM to Moneypoint Power Plant in 2003 and 2010
Edenderry / MBM
10,0
9,5
9,0
€/MWh
8,5
8,0
7,5
Theoretical, 2003
7,0
Technical, 2003
Theoretical, 2010
6,5
Technical, 2010
6,0
0
100
200
300
400
500
600
GWh
Figure 56 Availability of MBM to Edenderry Power Plant in 2003 and 2010
93
700
West Offaly / MBM
10,0
9,5
9,0
8,5
€/MWh
8,0
7,5
7,0
6,5
Theoretical, 2003
Technical, 2003
6,0
Theoretical, 2010
5,5
Technical, 2010
5,0
0
100
200
300
400
500
600
700
GWh
Figure 57 Availability of MBM to West Offaly Power Plant in 2003 and 2010
Lough Ree / MBM
11
10
€/MWh
9
8
Theoretical, 2003
Technical, 2003
7
Theoretical, 2010
Technical, 2010
6
0
100
200
300
400
500
600
GWh
Figure 58 Availability of MBM to Lough Ree Power Plant in 2003 and 2010
94
700
Tallow
There are eight rendering (carcass to food processing) plants that produce tallow namely:
Plant
Location
Country
Premier
Ballinasloe
Galway
Monery
Crossdoney
Cavan
College
Nobber
Meath
Waterford
Ferrybank
Waterford
Dublin
Dunlavin
Wicklow
Slaney
Bunclody
Wexford
Western
Ballyhaunis
Mayo
Munster
Cahir
Tipperary
Table 54. Tallow production plants in Ireland
Estimated tallow production (theoretical resource potential) in 2003 was 78 000 tonnes, which is equivalent to
774 GWh (9.92 MWh/t). The biggest tallow production is in the Dublin rendering plant, which accounts for
about 26% of total tallow production. Total tallow production is projected to slightly decrease to 71 000 tonnes
in 2010 (704 GWh).
More than half of the tallow produced is used as a top-up fuel in the rendering plants. Other outlets for tallow
include, for example, feed and pharmaceutical uses.
In this study the technical resource potential is the excess amount of the tallow after rendering plant’s own fuel
use. Technical resource potential in 2003 has been estimated at 37 000 tonnes (367 GWh) in 2003 and 33 000
tonnes (327 GWh) in 2010.
Plant
2003 Theoretical
2003 Technical
tonnes
tonnes
GWh
GWh
2010 Theoretical
tonnes
GWh
2010 Technical
tonnes
GWh
Premier
10 307
102
4 889
49
9 382
93
4 361
43
Monery
9 019
89
4 278
42
8 210
81
3 816
38
College
7 731
77
3 667
36
7 037
70
3 271
32
7 532
75
3 573
35
6 856
68
3 187
32
Dublin
20 615
205
9 779
97
18 765
186
8 722
87
Slaney
4 757
47
2 257
22
4 330
43
2 013
20
Waterford
Western
7 731
77
3 667
36
7 037
70
3 271
32
Munster
10 307
102
4 889
49
9 382
93
4 361
43
Total
78 000
774
37 000
367
71 000
704
33 000
327
Table 55 Theoretical and technical tallow resource potential in Ireland in 2003 and 2010
Tallow production costs
A base price for tallow that the rendering plants would get when selling tallow is not known. A base value of
EUR 5/MWh (EUR 50/tonne) ex factory has been used in this study.
Transportation costs used to define the supply curve are EUR 0.008/MWh per km for 2003 and EUR 0.010/MWh
per one km for 2010.
95
Supply curves
Moneypoint / Tallow
8,0
€/MWh fuel
7,5
7,0
Theoretical, 2003
6,5
Technical, 2003
Theoretical, 2010
Technical, 2010
6,0
0
100
200
300
400
500
600
700
800
GWh fuel
Figure 59 Availability of Tallow to Moneypoint Power Plant in 2003 and 2010
Edenderry / Tallow
7,0
€/MWh fuel
6,5
6,0
Theoretical, 2003
Technical, 2003
Theoretical, 2010
Technical, 2010
5,5
0
100
200
300
400
500
600
700
800
GWh fuel
Figure 60 Availability of Tallow to Edenderry Power Plant in 2003 and 2010
96
West Offaly / Tallow
7,0
€/MWh fuel
6,5
6,0
Theoretical, 2003
5,5
Technical, 2003
Theoretical, 2010
Technical, 2010
5,0
0
100
200
300
400
500
600
700
800
GWh fuel
Figure 61 Availability of Tallow to West Offaly Power Plant in 2003 and 2010
Lough Ree / Tallow
7,5
€/MWh fuel
7,0
6,5
Theoretical, 2003
6,0
Technical, 2003
Theoretical, 2010
Technical, 2010
5,5
0
100
200
300
400
500
600
700
GWh fuel
Figure 62 Availability of Tallow to Lough Ree Power Plant in 2003 and 2010
97
800
6.7
Technical applicability of available biomass to co-firing in power generation
As already described, all wood-based biomass fuels considered in this study - sawmill residues (bark, woodchips, sawdust), low-quality pulpwood (small diameter roundwood), forest residues (harvesting residues) and
wood pellets are the most suitable for co-firing at the coal- and peat-fired power plants in Ireland due to their
chemical and physical properties and many operating experiences (references) in co-firing applications in existing power plants worldwide.
Based on some operating experience, short rotation coppice willow may also be co-fired indirectly by gasifying
it first and then by burning syngas in an existing power boiler. It is not recommended to co-fire directly willow
alone due to lack of references in power generation. However, willow can also be co-fired directly together with
wood-based biomass fuels.
On the other hand, co-firing of straw, chicken litter and spent mushroom compost in power generation applications based on FBC or PC technology is not recommended by the Consultant due to unsuitable chemical and
physical properties of these biomass fuels leading to anticipated risks in boiler and power plant operation and
also due to the lack of references in comparable co-firing applications in existing power plants worldwide.
The following table summarizes the technical applicability to co-firing in power generation of biomass fuels
considered in this study.
Commercial references in:
Energy pro- FBC or PC
duction
technology
Pulpwood
Harvesting residues
Wood chips (byprod.)
Bark (by-prod.)
Sawdust (by-prod.)
Wood Pellets
SRC Willow
Straw
Chicken Litter
Spent Mushroom
Comp.
Chemical and physical
Electricity Gasifica- properties of the fuel to be
co-fired with FBC or PC
production tion
technology
Many
Many
Suitable
Many
Many
Suitable
Many
Many
Many
Many
Many
Many
Many
Many
Suitable
Many
Many
Many
Some
Many
Some
Many
Many
Many
Some
Some
Some
Many
Many
Many
Some
Some
Some
Many
Many
No
Some
No
No
Suitable
Suitable
Suitable
Suitable
Not recommended *)
Not recommended *)
Some
No
No
No
Not recommended *)
Table 56. Technical applicability of various biomass fuels to co-firing in power generation
*) Based on the current know-how and operating experiences these fuels are not recommended for the power
plants under review in this study. In the future it is quite possible that the status of these fuels in electricity production could change. However, the prerequisites would be that:
• reliable test runs with the fuel carried out
• boiler manufacturer and other equipment manufacturers (e.g. flue gas cleaning system, fuel and ash handling systems, etc.) must accept the use of these fuels
• power plant must have suitable permits (e.g. Waste Management Act)
The technical applicability of biomass fuels considered in this study to co-firing in power generation has also
been discussed in section 2.1 of this study (characterization and properties of biomass).
98
7
Estimating Feasible Level for Co-Firing with Biomass
7.1
General
The feasible level for co-firing has been estimated by applying supply-demand theory, according to which the
power plants under review will always choose such fuels to be incinerated which will maximise the overall plant
economy.
This section will focus only on those fuels that have been evaluated by the Consultant to be suitable and recommended (see section 6.7) for co-firing i.e. all wood-based fuels.
7.1.1 Summary of the technical supply potential
Relevant supply potential, as a function of fuel price of the selected biomass-based fuels for each power plant
has been expressed in the technical supply-curves presented in section 6.
The following table shows the maximum quantity of wood-based fuels available under the “Technical Supply
Potential” scheme.
Current technical supply potential
Future technical supply potential
1000 t, fresh
GWh fuel
1000 t, fresh
GWh fuel
Sawdust (by-prod.)
Bark (by-prod.)
Chips (by-prod.)
Pulpwood
Harvesting residues
50
194
22
132
216
97
388
44
231
380
62
202
51
414
252
121
404
99
728
443
SRC willow
-
-
57
99
Total
614
1 139
1 038
1 894
Fuel
Table 57 Current (2003) and future (2010) maximum technical supply potential of wood-based fuels
Bark (388 GWh) and harvesting residues (380 GWh) show the highest maximal volumes to be technically available today. In the future (2010) pulpwood shows the highest technical potential of about 730 GWh.
7.1.2 Summary of the technical co-firing potential
The current and future capabilities of the power plants under review to co-fire with different biomass types, as
well as their fuel paying capability (equivalent price) for the biomass-based fuel have been analysed in section
3.
Co-firing potential
Theoretical and technical co-firing potential is summarized in the following table:
99
Future, 2010
With modification
investment
Technical
Current, 2003
Without modification
investments
Theoretical
Technical
Moneypoint
% of total
GWh,fuel / 1 unit
GWh,fuel / 3 unit
10 (direct)
560
1680
5 (direct)
280
840
15 (indirect)
840
2520
Edenderry
% of total
GWh,fuel / 1 unit
50
1140
20
460
30
690
West Offaly Power
% of total
GWh,fuel / 1 unit
30
800
Lough Ree Power
% of total
GWh,fuel / 1 unit
30
550
Table 58 Current (2003) theoretical and technical and future technical co-firing potential
Today in theory Moneypoint could co-fire high-quality sawdust and wood pellets to generate approx. 560 GWh
per year (in each unit) without making any major modification investments in boiler and combustion technology. The technical co-firing possibilities are considerably less (280 GWh/unit) due to the plant’s existing fuel
handling system and equipment. In the future the modification investment considered would be biomass gasification, which would allow the plant to use safely large quantities of biomass-based fuels (840 GWh per unit).
Prices
A summary of the equivalent prices for biomass-based fuels that the power plants can afford to buy is presented in the following table.
Without modification
investments
Modification
investment
included
Effect of modification, 2010
Current, 2003
Future, 2010
Future, 2010
Total investment
Effect on fuel price
€/MWh
€/MWh
€/MWh
1 000 €
€/MWh
Moneypoint, 1 unit
5
5.3
2,92
2000
-2.38
Moneypoint, 3 units
5
5.3
2,92
6000
-2.38
11.3
12.7
12,67
200
-0.03
West Offaly Power
12.7
12,67
200
-0.03
Lough Ree Power
12.7
12,67
200
-0.03
Edenderry
Table 59 Estimated equivalent prices for biomass-based fuels and the effect of possible modifications on
the fuel price
In the table we can see that, for example, Edenderry would be able to pay some EUR 11.3/MWh for high-quality
wood-based fuels delivered to the power plant in the form of homogenous chips (particle size less that 5 cm). In
the future the price has been estimated to increase to EUR 12.7/MWh. The modification required at Edenderry
would enable the plant to use fuels the particle size of which is not very homogenous. To this end, the plant
should invest in a crusher and related auxiliary systems and equipment that would handle oversized wood particles from the screen. The cost of this fuel comminution system would be in the range of EUR 200,000 and the
effect on the fuel price would be about EUR 0.03/MWh.
100
Effect of emission trading on fuel prices and quantities under CO2 trade
According to the market indications, the unit price of CO2 is expected to vary between EUR 0 and EUR 30/t. The
effect of the prices of EUR 0, 10, 20 and 30/t of CO2 on the biomass-based fuel paying capability has been summarized in the following table.
Biomass-based fuel paying capability, €/MWhfuel
Time horizon
Price of CO2 in
emission trading, €/t
Modification
investment
Current, 2003
0
not included
5
Future, 2010
0
not included
5.3
Future, 2010
10
not included
8.5
Future, 2010
20
not included
Future, 2010
30
not included
Future, 2010
0
Future, 2010
West Offaly
Power
Lough Ree
Power
-
-
11.3
12.7
12.7
12.7
16.6
16.6
16.6
11.7
20.5
20.5
20.5
15
24.4
24.4
24.4
included
2.92
12.67
12.67
12.67
10
included
6.12
16.57
16.57
16.57
Future, 2010
20
included
9.32
20.47
20.47
20.47
Future, 2010
30
included
12.62
24.37
24.37
24.37
Moneypoint
Edenderry
Table 60. Effect of the carbon prices in emission trading on the biomass-based fuel paying capability
The power plants were allocated for free 73.7% of their GHG emissions for the first emissions trading period
(2005-2007). This means that the power plants either can buy relevant amounts of CO2 savings from the CO2
trading market or they can try to substitute fossil (traditional) fuels with CO2-free fuels in order to gain a needed
amount of emission savings. The objective of the power plants is naturally to minimise costs and choose the
most cost-effective measures to meet the GHG emission targets.
In this study it is assumed that the power plants will get the same amount of their emissions for free also for the
second emissions trading period.
Plant
Fuel
Amount of
CO2 to be
saved
Amount of CO2-free fuels Amount of main fuel
to be replaced with
to be used to achieve
required emission savings CO2-free fuel
t of CO2
GWh fuel
1000 t
Lough Ree Power
Peat
198 729
509
238
West Offaly Power
Peat
298 093
764
357
Edenderry
Moneypoint (three
units)
Peat
209 307
536
251
Coal
1 498 414
4 614
664
Table 61 Emission saving requirements by power plant
7.2
Current feasible co-firing level
At present, Moneypoint cannot purchase any biomass-based fuels in the prevailing market situation where the
world market price for coal is low and indigenous biomass-based fuels prices are high.
Edenderry, West Offaly Power and Lough Ree Power can afford to buy bark and sawdust within the range of
170-190 GWhfuel. This is considered to be the current feasible co-firing level. However, one must bear in mind
that all power plants are competing with each other for the same limited fuel resources.
101
CURRENT (2003, no emissions trading)
Wood SRC
EUR/CO2 Pulp Harvesting Sawmill
Total
Bark Sawdust
pellets willow
t
Wood residues
chips
Moneypoint
Edenderry
West Offaly Power
Lough Ree Power
0
0
0
0
-
-
-
80
100
108
90
90
75
-
-
0
170
190
183
Table 62. Current feasible co-firing potential (no emissions trading, no modification)
Moneypoint, Technical fuel potential vs. feasible co-firing level , 2003
29
27
25
23
21
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
€/MWh fuel
19
17
15
13
11
9
7
5
0
50
100
150
200
250
300
350
400
450
GWh fuel
Figure 63. Current feasible co-firing potential at Moneypoint (without modification)
102
500
Edenderry, Technical fuel potential vs. Feasible availability, 2003
29
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
27
25
23
21
€/MWh fuel
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 64. Current feasible co-firing potential at Edenderry (without modification)
West Offaly, Technical fuel potential vs. Feasible availability, 2003
29
27
25
23
Sawchips
Sawdust
Bark
21
Pulpwood
harvesting residues
€/MWh fuel
19
Wood Pellets
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 65. Current feasible co-firing potential at West Offaly Power (without modification)
103
Lough Ree, Technical fuel potential vs. Feasible availability, 2003
29
27
25
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
23
21
€/MWh fuel
19
17
15
13
11
9
7
5
0
50
100
150
200
250
300
350
400
450
500
GWh
Figure 66. Current feasible co-firing potential at Lough Ree Power (without modification)
7.3
Future feasible co-firing level
7.3.1 Without modification investments
In the future Moneypoint will be able to purchase only sawdust if the market price for carbon will be EUR 20 or
30/t of CO2.
Edenderry, West Offaly Power and Lough Ree Power have the opportunity to acquire a large variety of woodbased fuels whatever the market price for carbon will be.
Feasible co-firing volumes for each power plant can be read from the table hereunder.
104
FUTURE (2010, with emission trading, without modification
investments)
Wood SRC
EUR/CO2 Pulp
Harvesting Sawmill
Bark Sawdust
Pellets Willow
t
Wood residues Chips
Moneypoint
0
10
20
10
30
58
Edenderry
0
70
40
55
100
10
325
200
5
205
110
20
650
395
45
318
120
30
60
1 000 728
443
400
120
West Offaly Power 0
130
75
85
90
10
350
210
25
200
110
20
395
40
330
728
120
30
60
460
728
443
400
120
Lough Ree Power 0
65
205
50
70
10
330
410
10
220
110
20
45
320
728
443
120
30
728
443
70
400
120
350
-
Total
0
0
10
58
265
845
1 528
2 751
380
895
1 613
2 211
390
1 080
1 656
2 111
Table 63. Future feasible co-firing potential (with emissions trading, no modification)
MONEYPOINT, Technical biomass-based fuel availability, 2010
35
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
SRC Willow
33
31
29
27
25
€/MWh fuel
23
21
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 67. Future feasible co-firing potential at Moneypoint (with emissions trading, no modification)
105
EDENDERRY, Technical biomass-based fuel availability, 2010
35
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
SRC Willow
33
31
29
27
25
€/MWh fuel
23
21
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 68. Future feasible co-firing potential at Edenderry (with emission trading, no modification)
WEST OFFALY, Technical biomass-based fuel availability, 2010
35
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
SRC Willow
33
31
29
27
25
€/MWh fuel
23
21
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 69. Future feasible co-firing potential at West Offaly Power (with emission trading, no modification)
106
LOUGH REE, Technical biomass-based fuel availability, 2010
35
33
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
SRC Willow
31
29
27
25
€/MWh fuel
23
21
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh
300
350
400
450
500
Figure 70. Future feasible co-firing potential at Lough Ree Power (with emission trading, no modification)
7.3.2 With modification investments
FUTURE (2010, with emission trading, with modification investments)
Wood SRC
EUR/CO2 Pulp
Harvesting Sawmill
Bark Sawdust
Pellets Willow
t
Wood residues Chips
Moneypoint
0
10
20
30
75
45
12
Edenderry
0
69
39
54
98
10
319
196
5
201
108
20
637
387
44
312
118
30
59
980
713
434
392
118
West Offaly Power 0
127
74
83
88
10
343
206
25
196
108
20
387
39
323
713
118
30
59
451
713
434
392
118
Lough Ree Power 0
64
201
49
69
10
323
402
10
216
108
20
44
314
713
434
118
30
713
434
69
392
118
343
Table 64. Future feasible co-firing potential (with emission trading and modification)
107
Total
0
0
0
132
260
828
1 497
2 696
372
877
1 581
2 167
382
1 058
1 623
2 069
MONEYPOINT, Technical biomass-based fuel availability, 2010
35
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Wood Pellets
SRC Willow
33
31
29
27
25
€/MWh fuel
23
21
19
17
15
13
11
9
7
5
0
50
100
150
200
250
GWh fuel
300
350
400
450
500
Figure 71. Future feasible co-firing potential at Moneypoint (with emission trading and modification)
7.4
Summary
The pilot phase of the EU emissions trading scheme is due to commence in January 2005. In compliance with
its obligations, Ireland notified its National Allocation Plan (pilot phase 2005-2007) to the European Commission
on 31st March 2004. Based on the National Allocation Plan as notified to the Commission, the allocated emission to the traded sector for 2005-2007 is 67.5 Mt CO2e, or 98.2% of the base case scenario GHG emissions from
the sector for that period. Within the entity level allocation, the power plants, which are the subject of this
study, have been allocated allowances which are 73.7% of their ‘relevant emission’6. Therefore, the power
plants will be required to reduce their greenhouse gas emissions or to purchase carbon credits, amounting to a
total of 2,204,543 t CO2e (~1,498,000 t from coal-fired generation and ~706,000 t from peat-fired generation).
The study commissioned by the Irish Government to determine the share of national greenhouse gas emissions
for emissions trading in Ireland 7 estimates that the emissions allocated to the traded sector for the 2008-2012
(Kyoto) period will represent an average of 84% coverage of the traded sector’s base case scenario GHG emissions for this period. The entity level allocations have not been announced for this second “Kyoto” phase of the
emissions trading scheme, and therefore the allocation to individual power plants for this period is not known.
The feasible potential for co-firing with biomass in the solid-fuel burning power plants together with the potential GHG savings are shown in Table 65 below, and graphically in Figure 72.
6
For Edenderry Power Plant and Moneypoint Generating Station, the relevant emission was taken to be the average greenhouse gas emission in the period 2002-2003. For Lough Ree Power and West Offaly Power Plants, the
relevant emissions were set at the predicted greenhouse gas emissions.
7
ICF Consulting, Byrne Ó Cléirigh Ltd., February 2004, Determining the Share of National Greenhouse Gas
Emissions for Emissions Trading in Ireland, Final Report, submitted to the Department of the Environment, Heritage and Local Government, Ireland.
108
Peat
Coal
Total
GWh
t CO2e
GWh
t CO2e
GWh
t CO2e
170
66 353
0
0
170
66 353
0 €/t of CO2e
460
179 544
0
0
460
179 544
10 €/t of CO2e
1 100
429 343
0
0
1 100
429 343
20 €/t of CO2e
1 700
663 530
0
0
1 700
663 530
30 €/t of CO2e
2 040
796 236
132
42 863
2 172
839 099
2003
0 €/t of CO2e
2010
Table 65. The feasible level for co-firing with biomass and related GHG savings
109
GWhfuel
2003
2010
Co-firing with coal
4500
4000
3500
3000
Technical co-firing potential
2500
10 €/t of CO2
1000
Feasible co-firing with
alternative CO2 prices
500
0 €/t of CO2
Co-firing with peat
20 €/t of CO2
1500
INDIGENOUS
BIOMASS SUPPLY
30 €/t of CO2
2000
Biomass imports
0
Substitution for peat
0
0,1
Feasible potential for
CO2 -reduction with
alternative CO2 prices
0,2
0,3
0,4
0 €/t of CO2
10 €/t of CO2
0,5
0,6
20 €/t of CO2
0,7
0,8
30 €/t of CO2
1
Substitution for coal
0,9
Technical potential for CO2 reduction
1,1
1,2
1,3
1,4
1,5
1,6
1,7
Mt of CO2
2003
2010
Figure 72. Technical and feasible co-firing and related CO2e reduction potential in the studied power
plants with alternative CO2e emissions trading price levels.
The co-firing potential of the Moneypoint coal-fired power plant is very low. The analysis indicates that it would
not be economically sensible for the plant to co-fire with biomass under most scenarios considered. Even under
the emissions trading scenario where it is assumed that the clearing price for carbon credits under the EU ETS
scheme is EUR 30/t CO2e, the total feasible GHG savings which could be achieved from biomass correspond to
less than 1% of the annual GHG emissions from the plant. On this basis alone, it is unlikely that Moneypoint
would opt to use co-firing biomass in their strategy to meet the requirements under the National Allocation
Plan.
110
The potential for emissions savings at the peat-fired plants is more significant. Assuming a carbon credit clearing price of EUR 10/t CO2e, as indicated by the forward market price for EUA for the pilot phase of the EU ETS,
the feasible potential for GHG savings is estimated to be 429,343 t CO2e at the peat-fired plants by 2010. This is
equivalent to approximately 16% of the annual emissions from the peat-fired plants. The potential would be
even higher for higher clearing prices of carbon credits. While the feasible potential for 2007 may be somewhat
lower than that projected for 2010, the analysis suggests that co-firing with biomass could help to meet a significant proportion of the peat-fired plants’ obligations under the EU ETS.
111
8
Institutional Mechanisms to support Biomass and Biomass –based Electricity Production in Ireland
8.1
Background
As part of the European Union, Ireland has committed to meeting environmental targets in respect to greenhouse gas reductions and electricity generation from renewable sources. Ireland has agreed to limit the growth
in greenhouse gas emissions to 13% above the 1990 level by the target period 2008-2012. Under the latest
‘Business as Usual’ Projections8, Ireland’s emissions in 2010 are predicted to be 69.4 Mt CO2 e, i.e. 30% above the
1990 levels.
Under EU 2001/77/EC (the RES-E Directive), Ireland has also been set an indicative target of generating 13.2% of
its annual electricity requirement from renewable energy sources by 2010. This is equivalent to approximately
4.3 TWh per year.
8.2
Existing policy
8.2.1 Support for peat generation
The Edenderry Power, Lough Ree Power and West Offaly Power peat-fired power stations have 15-year power
purchase agreements with ESB PES for 100% of their output, back-to-back with a 15-year fuel purchase agreement from Bord na Móna. The running of the peat-fired power plants is supported through a Public Service Obligation (PSO) on all electricity users, as described below.
8.2.2 Support for renewable energy generation
Since 1994, the development of electricity generating capacity from renewable energy has been encouraged
through a series of government-supported Alternative Energy Requirement (AER) competitions. The objective
of the AER is to increase the contribution of renewables in the overall electricity generating mix. As with peatfired generation, the AER programme is supported through a PSO on all electricity users.
The AER involves a series of tendering competitions, in which prospective generators are invited to compete,
based on price per unit of electricity, for contracts to sell electricity to ESB. Successful competitors are offered
ESB power purchase agreements of up to fifteen years. Applicants must bid at or below the cap price in the
competition - the lowest bids received will be selected to receive the offer of a Power Purchase Agreement
(PPA) up to the limit of the overall threshold outlined, in advance, for each category.
To date, biomass has played a minor role in Ireland’s renewable energy portfolio. AER 1 to 5 brought just 15
MWe of landfill gas generation capacity on stream. AER 6 included separate tranches for biomass CHP, landfill
gas and biomass anaerobic digestion, awarding an additional 34.3 MWe of generating capacity.
As a pre-requisite to entry to the AER VI competition, planning permission for the construction of the project, an
up-to-date tax clearance certificate in respect of the applicant and confirmation that applications had been
submitted to the Commission for Energy Regulation (CER) for the associated authorisation to construct an electricity-generating station and a licence to generate electricity were required.
Three biomass CHP projects were successful, as follows:
8
ICF Consulting & Byrne Ó Cléirigh Ltd., 2004, Determining the Share of National Greenhouse Gas Emissions
for Emissions Trading in Ireland, submitted to the Department of the Environment, Heritage and Local Government, Ireland.
112
Location
Monaghan
Cork
Offaly
Site
Killycarron, Emyvale
Graingers Sawmills, Enniskeane
Ballyfore, Edenderry
Developer
Monopower Ltd.
SWS Forestry Services
Art Generation
Ltd.
Capacity (MWe)
22.5
2.55
1.45
8.2.3 Public Service Obligation (PSO)
The PSO requires ESB PES to purchase electricity generated from peat and renewable, sustainable or alternative
forms of energy in following Government aims for security of supply. The amount of the Levy is the excess of
the ESB PES’s allowed costs for bought-in and owned peat-fired generation and alternative energy requirements (AER) over the Best New Entrant price for electricity. The levy includes an economic return on investment,
where relevant, and any other revenue accruing to ESB PES associated directly with peat-fired generation and
AER generation schemes. The levy is imposed as a fixed charge, based on the customer’s installed capacity and
is included as a separate line item on the electricity bills issued by each supplier. The monies collected are then
passed on to ESB.
ESB PES submit their estimated costs to CER of generating electricity from their peat-fired stations and the estimated cost of purchases from AER and Edenderry Power Ltd. on an annual basis for audit.
The CER has determined the annual levy for 2004 as follows:
Customer Category
Annual Levy Amount
Domestic customers
EUR 18.16 / customer
Small commercial customers (maximum
import capacity of less than 30kVA)
EUR 54.98 / customer
Medium and large customers (maximum
import capacity of greater than 30kVA)
EUR 9.99 / kVA
The total amount to be recovered via the Levy in 2004 is EUR 74.814 million.
8.2.4 Research and development policy
Sustainable Energy Ireland promotes and assists environmentally and economically sustainable, production,
supply and use of energy in Ireland. The National Development Plan has made funding provision of EUR 223
million to support implementation of the Government's sustainable energy policy through Sustainable Energy
Ireland.
Under this policy, a EUR 16.25 million programme of support for research, development and demonstration on
renewable sources of energy and related topics has been launched. Quoted priorities for biomass from the
Strategy document9 include biomass resource studies, plant feasibility studies and development of fuel supply
strategies, in addition to biomass demonstration projects.
9
Sustainable Energy Ireland, 2002, Renewable Energy Research, Development & Demonstration Programme
Strategy.
113
8.3
Future policy
8.3.1 Carbon energy taxation
The Irish Government has announced that they intend to introduce a carbon energy tax from the end of 2004.
Having published a consultation paper inviting submissions, the Government has received submissions from a
large number of interested parties and is now in the process of agreeing the mechanisms to implement the tax.
Based on the consultation document, it is proposed that an excise-type tax will be placed on all fossil fuels. It is
envisaged that any company involved in the EU emissions trading scheme will not be subject to the carbon energy tax. Therefore, the power plants under review in this study will not be impacted by the introduction of a
carbon energy tax.
8.3.2 Emissions trading
The pilot phase of the EU emissions trading scheme is due to commence in January 2005. In compliance with
its obligations, Ireland notified its National Allocation Plan (pilot phase 2005-2007) to the European Commission
on 31st March 2004.
The Environmental Protection Agency (EPA) has been given the responsibility for implementing the Emissions
Trading Directive in Ireland by the Government. Based on the results of a study by ICF Consulting and Byrne Ó
Cléirigh for the Department of the Environment, advising them regarding the allocation between sectors, a total
of 67.5 Mt CO2e has been allocated to the traded sector for the period 2005-2007. The EPA is responsible for
allocating the emissions between the various installations covered by the trading scheme.
Based on the National Allocation Plan as notified to the Commission, the power plants, which are the subject of
this study, have been allocated 73.7% of their ‘relevant emission’. In the case of Edenderry Power Plant and
Moneypoint Generating Station, the relevant emission was taken to be the average greenhouse gas emission in
the period 2002-2003. For Lough Ree Power and West Offaly Power Plants, the relevant emissions were set at
the predicted greenhouse gas emissions.
The ICF/BÓC report notes that the impact of the EU ETS on emissions from the power sector will be highly dependent on the way in which generators are able to pass through the increase in production cost by the Commission for Energy Regulation (CER). If generators are only allowed to recover the direct cost of their allowance
deficit through tariffs (Regulated Scenario), there will be no incentive for generators to reduce emissions. If,
however, generators are able to pass through the actual cost and opportunity cost (Competitive Market Scenario) of allowances to final prices, emission levels are likely to decline relative to the Base Case as the cost of
GHG emissions will be more accurately reflected in generating and dispatch decisions. Only under the second
scenario would there be an incentive for generators to reduce emissions by, for example, co-firing with biomass,
which would be treated as carbon neutral. While the CER have yet to determine the way in which generators
will be able to pass through costs, the report based its analysis on the Competitive Market Scenario as the more
prudent approach.
8.3.3 RES-E Directive
The Irish Government policy is to meet the indicative target of generating 13.2% of its annual electricity requirement from renewable energy sources by 2010, as set under EU 2001/77/EC (the RES-E Directive). Emissions
projections from the energy sector for 2010, which were used in the ICF/BÓC study, and hence have fed
through to Ireland’s National Allocation Plan for the EU ETS, have assumed that this target will be met.
The Department of Communications, Marine and Natural Resources recently published a consultation document inviting submissions on options for future renewable energy policy targets and programmes. Four specific types of direct financial support options were identified for consideration in the consultation process, as
follows:
Feed-in tariff;
Competitive tender (per AER mechanism);
114
Production credit;
Renewable obligation with renewable credits.
Depending on what type of future support mechanism is put in place for biomass to replace the AER mechanism, generators could potentially receive additional incentives to co-fire biomass in the solid fuel burning
power plants in addition to emissions savings under the EU ETS. It should be noted that any restrictions regarding the type of technology or type of biomass that may be used, for example, requirements for the biomass mix
to include a fixed percentage of energy crops or that newer technology gasification plant be used, may serve to
reduce this incentive.
The consultation document also outlines a number of secondary support measures, which could be introduced
to support renewables, including grants, tax incentives and low interest loans. As noted earlier in this report,
with the exception of the option to install a gasifier at Moneypoint, the level of investment required to co-fire in
the existing power plants is expected to be low. Therefore these secondary support mechanisms are expected
to be of lesser importance in the context of the power plants, which are the subject of this study.
8.4
Additional potential mechanisms to boost co-firing potential
In order to maximise the potential for co-firing biomass in the power plants, it will be necessary to maximise the
quantity of biomass, which is made available from the various sources identified in Section 3 of this report. In
particular, harvesting residues and short rotation coppice are not readily available for co-firing at present.
COFORD has carried out a study into the harvesting of forest residues 10, including the development and testing
of a prototype mobile bundling machine suitable for use in Irish conditions. While the work represents a significant contribution to the experience base, additional development work will need to be supported if forestry
residue is to be harvested on a commercial scale.
While SRC has been identified as having considerable potential for energy generation in Ireland in the future,
the resource available at present is effectively zero. In order to encourage planting of energy crops, it is likely
that government support in the form of planting grants will be required.
10
COFORD, ‘Forest Residues: Harvesting, Storage and Fuel Value’
115
116
Appendix 1.
Biomass resource and co-firing definitions
Biomass resources as well as co-firing potential are defined in this study as theoretical, technical and
feasible.
The theoretical biomass resource potential reflects the theoretical maximum resource potential that
exists at current or foreseen future production rates. Theoretical resource potential is presented as
“demand curve” to each studied power plant. The demand curve shows in x-axis the estimated quantity (GWh) of the resource available from each supply point and in y-axis the price (€/MWh) of the resource delivered from the supply point to the power plant. The price consists of the start value of the
resource at its origin and the transportation cost to the power plant.
The technical biomass resource potential considers alternative uses of the biomass resource as well
as the technical and ecological availability constraints of each resource. E.g. it is not reasonable to
compile all harvesting residues from a clear felling area because part of the material (e.g. green mass)
is best left on the site as a nutrient matter. Technical resource potential is presented also as a “demand curve” to each studied power plant.
The feasible biomass resource potential in the case of each power plant is presented based on the
biomass resource “supply curves” and the fuel paying capability of the power plant. Feasible biomass
resource means such quantity of biomass that the power plant can afford to purchase at the same or
lower price that it is purchasing fuel peat or coal. Feasible biomass resource potential is estimated to
reflect current fuel prices and fuel/energy taxation and on the other hand to reflect the situation in
the year 2010 taking into account the estimated fuel peat and coal price development as well as the
effects of the foreseen emission trading or alternatively carbon energy taxation.
The theoretical co-firing potential reflects only the estimated capability of the boiler and other combustion equipment (burners) to co-fire with solid and good quality biomass without notable risks in
boiler operation. This is usually expressed as % of the fuel input. E.g. 10% theoretical co-firing potential in a coal fired power plant means that 10% of the fuel input could be biomass and the majority
90% would remain to be coal.
The technical co-firing potential considers the operational possibilities (bottlenecks) of not only the
boiler and other combustion equipment (burners) but also related boiler plant’s auxiliary systems
and equipment (e.g. fuel and ash handling systems, flue gas cleaning system, etc) to handle biomass.
The feasible co-firing potential considers plant economy so that an energy producer will always use
most competitive fuels in order to maximise the plant’s overall economy. Where modification investments are needed to enable the plant to start to use biomass-based fuels or to increase its current use, the effect of the modification investment is added to the fuel purchase price. Feasible cofiring potential considers the potential plant modifications required to implement the substitution of
biomass to the maximum level that is technically feasible.
117
Appendix 2.
Geographical location of power plants, panel board mills and sawmills
118
Legend
Address
Power Plants: (white)
1 Moneypoint
Edenderry
2
3 Lanesborough
4 Shannonbridge
County
Killimer
Clare
Ballykilleen
Offaly
Longford
Offaly
Panel Board Mills: (blue)
1
2
3
4
5
Finsa Forest Products
Smartply Europe
Masonite Ireland
Spanboard Products
Wayerhaeuser Europe
Scarrif
Belview
Carrick-on-Shannon
Coleraine
Clonmel
Clare
Waterford
Leitrim
Derry
Tipperary
Magherafelt
Enniskillen
Newtowngore
Coolrain
Limavady
Glenties
Corr na Móna
Fermoy
Longford
Portlaoise
Ballon
Ballygar
Banagher
Macroom
Enniskeane
Aughrim
Mohill
Coleraine
Mountrath
Hollyford
Rathdrum
Derry
Fermanagh
Leitrim
Laois
Derry
Donegal
Galway
Cork
Longford
Laois
Carlow
Galway
Offaly
Cork
Cork
Wicklow
Leitrim
Derry
Laois
Tipperary
Wicklow
Enniskeane
Enniskillen
Emyvale
Cork
Fermanagh
Monaghan
Sawmills: (red)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Balcas Timber Ltd.
Balcas Timber Ltd.
Balcas Timber Ltd.
Coolrain Sawmills Ltd.
Drenagh Sawmills Ltd.
Drenagh Sawmills Ltd.
ECC Teo
Glennon Bros Ltd.
Glennon Bros Ltd.
Laois Sawmills Ltd.
Murray Timber Products Ltd.
Murray Timber Products Ltd.
Nordale (Banagher Sawmills)
Palfab Ltd.
SFE (Grainger Sawmills Ltd.)
Woodfab Timber Ltd.
Crowe's
Diamond's
Irish Forest Prod (ceased)
O'Grady's
Wood Industries
Biomass CHP -Plants (yellow)
1 Graingers / SFE
2 Balcas
3 Monopower Ltd.
119
APPENDIX 3
Technology for large-scale chip production
Data source: Wood Energy Technology Programme, 1999-2003 , Pentti Hakkila, VTT Processes (pages: 17-30)
TECHNOLOGY FOR LARGE-SCALE CHIP PRODUCTION
A3.1 System development
A prevailing feature of the programme is a systems approach. A forest chip production system consists of a
sequence of individual operations performed to process biomass into commercial fuel and transport it
from source to plant. The main phases of chip procurement are purchase, cutting, off-road transport from
stump to roadside, comminution, measurement and secondary transport from roadside to mill. The system
offers the organization, logistics and tools to control the process.
The efficiency of a procurement system is highly dependent on both the environment and the infrastructure in
which it is operating. Economic, social, ecological, industrial and educational factors, as well as local traditions, also have an effect. Consequently, no single production system is optimal in all countries or in all
conditions within a given country. Under Finnish conditions, the operating environment of forest chip
procurement is characterized by the following attributes:
• The majority of the forests belongs to private non-industrial owners, the size range of holdings being
typically 20–200 ha. This means small average sales volumes, cramped landing areas at nearby road sides,
and frequent shifting of machines from site to site. These drawbacks increase the cost of transactions and
the scaling of biomass, decrease the operational availability of machines and so place considerable demands upon control of large-scale chip procurement.
• Up to 90 % of harvestable biomass potential is linked to the harvesting of industrial roundwood (Figure
10). The production of forest chips must therefore be integrated with the existing timberprocurement, but
the degree of integration may vary.
• All logging machines and timber trucks are owned by independent contractors. The production of forest
chips rests on private contractors and the profitability of their enterprises.
• The Finnish forests belong to the Pan-European Forest Certification System (PEFC). Good forest management practices are essential also for the production of forest fuels.
• The demand for chips varies seasonally, especially in smaller heating plants. It is highest in the winter and
lowest in the summer, which causes fluctuations in employment. In large CHP plants, the demand for chips
is more stable.
• Only small plants can base their fuel supply exclusively on forest chips. To secure fuel availability, to reduce the costs, and to level out quality variation, larger plants burn forest chips mixed with bark, sawdust,
peat or coal. To keep the fuel mixture constant, chip arrivals at the plant must be strictly scheduled. This
requirement complicates the logistics of forest chip procurement.
Compatibility of equipment
The integration of forest chip production with the procurement of roundwood opens up possibilities for
cost savings. It is feasible to use the existing transport equipment for forest biomass when possible. However, due to differences in handling properties and destinations, special equipment is also needed.
Forest machine contractors harvest over 40Mm3 of roundwood annually. Delivery sales by self-employed
forest owners included, timber truck contractors correspondingly haul 55 Mm3 of roundwood. The Nordic
120
cut-to-length system is the only technology employed when harvesting timber for the forest industries.
The equipment used by different contractors is compatible, allowing organizational flexibility.
Unfortunately, little machine compatibility has been achieved in the procurement of forest chips, although
the annual production is not yet much more than 1 Mm3. The lack of compatibility is because the logging
conditions vary considerably from the early uncommercial thinning of young stands to the final harvest of
mature stands, and because the technology is still new. Several alternative production systems are in use,
and each system employs special equipment that is not necessarily compatible with other systems. Poor
compatibility increases the commercial risks for contractors and plants when they invest in new equipment,
and it may result in underemployment and unnecessary shifting of harvesting machines and trucks from
one site to another.
Alternative systems
A forest fuel production system is built around the comminution phase. The position of the chipper or
crusher in the procurement chain largely determines the state of biomass during transportation and,
consequently, whether subsequent machines are dependent on each other. Comminution may take place
at the source, at the road side or landing, at a terminal, or at the plant where the chips are to be used. Four
alternative production systems have been studied in the Wood Energy Technology Programme (Figure
73).
121
Figure 73. Alternative systems for the production of forest chips. Source VTT.
Comminution at the source, or in the terrain, requires a highly mobile chipper suitable for cross-country
operations and equipped with a tippable 10–20 m3 chip container. The chipper moves in the terrain on
strip roads and transfers the biomass with its grapple loader to the feeder of the chipping device. When
the chipper container fills up, the load is hauled to the road side and tipped into a truck container, which
may be on the ground or on a truck trailer (Figure 74).
As a single machine carries out both the comminution of biomass and the off-road transport of chips,
the cost of shifting machines from site to site is reduced, and smaller logging sites become commercially
viable. The use of containers weakens the interdependence between the chipper and the truck, although it is not entirely removed. Large landing areas are not needed, but a level and firm site is necessary for the truck containers.
For off-road operation, the chipper must be as light as possible, although its strength and stability may
suffer. Even so, terrain chippers tend to be too heavy for use on soft soils, while use of crushing equipment in terrain is out of question. A terrain chipper requires flat and even ground and, because of its
small load size and slowspeed, its range is less than 300–400 m. Snow causes problems in the winter and
results in an increased moisture content of chips, unless the terrain chipper operates at a landing.
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When large volumes of forest fuels are produced, the terrain chipping system becomes difficult to control. At present, the role of the system is diminishing.
Comminution at a landing is performed in smaller operations with farm tractor-driven chippers and in
large-scale operations primarily with heavy truck-mounted chippers or crushers. The biomass is hauled
with forwarders to the landing and bunched onto 4 to 5 m high piles. This facilitates operation in difficult
terrain and in winter conditions and allows longer off-road hauling distances. The forwarder operates
independently of the chipper. The comminuted biomass from the chipper is blown directly into a 100 to
130 m3 trailer truck, a process that makes the system hot and vulnerable, i.e. subsequent machines are
dependent on each other. A wider landing area is required than in the alternative systems because of
the large road-side inventories of biomass and the simultaneous presence of the chipper and the truck.
To avoid the system from over-heating, the truck-mounted chipper and chip truck can be replaced by a
single chipper truck (Figure 75). This blows the chips directly into its own containers and then hauls the
load to the plant. As the chipper truck is equipped with its own chipping device and crane, load capacity
suffers and the operation radius around the plant is reduced.
Landing chippers do not operate off road and can therefore be heavier, stronger and more efficient than
terrain chippers. If the biomass, such as stump and root wood, is contaminated by stones and soil, it is
possible to use crushers that are more tolerant instead of chippers (Figures 76 and77).
The close linkage of comminution and trucking results in waiting and stoppages and thus reduces the
operational availability. On the other hand, the landing chippers are reliable and their technical availability is rather high. The system has so far kept its position as the basic solution of large-scale procurement
of forest chips.
Comminution at a terminal or plant means that road transportation of the biomass takes place before the
size reduction. The biomass is transported to the terminal or plant in the form of undelimbed tree sections, whole small-trees, loose logging residues or bundles. Lowbulk density restricts the operation radius, unless the biomass is bundled.
At large plants, comminution can be performed with efficient stationary crushers at low cost. At satellite
terminals or smaller plants, the use of transportable chippers or crushers is more feasible, although the
productivity of comminution is lower and the cost higher.
Figure 74. Pika Loch 2000 terrain chipper (Courtesy of S.Pinomäki Oy)
123
Figure 75. TT-97 RMS chipper truck (Courtesy of Biowatti Oy).
Figure 76. Truck-mounted Giant chipper comminuting logging residues at a landing (Courtesy of LHM
Hakkuri Oy).
124
Figure 77. Trailer-mounted Diamond tub grinder crushing stump and root wood at a landing (Courtesy
of UPM-Kymmene Oyj).
Figure 78. Timberjack 1490D residue bundler in a clear-cutting area (Courtesy of Timberjack Oy)
125
Figure 79 Off-road transport of residue bundles with a conventional forwarder (Courtesy of Timberjack
Oy).
Comminution at the plant, based on the bundling of logging residues and crushing of bundles with stationary equipment, has been one of the key areas of technological development in the Wood Energy
Technology Programme. In this system, logging residues are compressed and tied into 60–70 cm diameter, 3 m long bundles or composite residue logs (CRL) (Figure 78). A bundle of green residues weights 500
kg and has an energy content of about 1 MWh. Bundles are transported to the road side using a conventional forwarder (Figure 79) and on to plant with a conventional timber truck. About 65 bundles or 30
tons form one truck load. Whether it will be necessary, for safety reasons, to equip the truck with rear
and side walls, is still an open question.
Efficient process control
The CRL technology is still new and has considerable development potential. Although it was introduced
in Finland as recently as in 2001, many of the major producers of forest chips have already started to
employ it. The rapid success of the system is a consequence of the recent development of bundling
techniques and the many indirect advantages:
• The machines involved operate independently of each other making the system cool and reliable.
• The integration of bundle production in the procurement of industrial roundwood is simple, as off-road
and on-road transportation can be performed with standard equipment.
• The bundler produces accurate real-time information about the daily production and inventories. Scaling becomes cost-free.
• The storage of bundles is simple: storage space requirement is reduced, little loss or deterioration of
the biomass occurs, and long-term buffer storage is possible.
• Bundles can be unloaded from a vehicle and stored at any stage of the production chain. This possibility, as well as reliable information about the biomass inventories, create good conditions for efficient process control.
• The noise, dust and litter problems, which may occur in conjunction with comminution at a landing, are
avoided.
• The reliability of the fuel deliveries is greatly improved, while the overhead costs are reduced.
126
A3.2 System building components
As a chain is as strong as its weakest link, identifying and solving problem areas play a key role in system
building. This typically requires the development of new machines, but it may also require new working
techniques and work organization. Although the system approach is the principle of the programme,
some projects focus on narrower topics aimed at developing and demonstrating solutions for bottlenecks in a system.
The efficiency of comminution is one of the key areas. Efficiency is understood in its broad sense: high output, flexible adjustment in the system, reliability, good product quality, and minimum harmful environmental impact. Among the comminution equipment developed and studied are the Pika Loch 2000 chip
harvester of S. Pinomäki Ky, capable of tipping its load from 4.2 m height directly onto a truck trailer; the
truck-mounted Giant chipper of LHM Hakkuri Oy, capable of producing evensized chips from different
kind of loose and bundled biomass; the farm tractor-mounted TT-97 RMT drum chipper and the TT-97
RMS chipper truck from Heinola Sawmill Machinery for carrying out both road-side chipping and chip
transport; a two-phase crusher prototype; and the 1490D residue bundler of Timberjack Oy.
The programme has also participated in the development and demonstration of the Timberjack 720 and
730 multi-tree feller heads for the mechanization of small-tree harvesting from early thinnings; the Valtra
farm tractor-based residue forwarder with enlargening load space from MetsäenergiaKy (Figure 80); the
farm tractor based, load-compacting HavuHukka residue forwarder from Vapo Oy for transporting residues from source to satellite terminal (Figure 81), and a forwarder-based prototype combi-machine developed by Antti Varis for collection and hauling logging residues and simultaneously preparing the site
for regeneration.
Figure 80. A Valtra farm tractor-based residue forwarder with enlargening load space (Courtesy of TTSInstitute).
127
Figure 81 The load-compacting HavuHukka forwarder for transporting residues from logging site to satellite terminal (Courtesy of Vapo Oy).
Machine development is frequently accompanied by method development, including aspects such as work
techniques and adjustments in the procurement system. As machine contractors are usually paid by
piece rate, measuring the performance may become a source of friction in the procurement system.
Measuring unprocessed biomass is difficult, and for a low-value product the cost of measurement must
be kept low. Therefore, methods for the measurement of biomass must be developed. One of the research
projects concerned with adding crown mass estimation to the computerized stem volume measurement
of a one-grip harvester, based on the diameter and taper of the stem. Another project concerned a simple estimation method for determining the performance of a forwarder in the off-road transport of logging residues from stump to road side. In the CRL system, measurement problems have been solved in
an ideal way, as the volume and energy content of a bundle is sufficiently constant and the bundler produces cost-free real-time information about the number of bundles.
A3.3 Assessing cost factors of chip production
While fossil fuels occur in large deposits and can be produced at a constant cost, forest fuels are scattered and must be collected from a large number of stands. Technical logging conditions in these stands
vary widely, and the variations are reflected in the productivity and cost of work.
The cost factors of forest chip production are not known sufficiently. When the Wood Energy Technology Programme was established, this lack of elementary knowledge was recognized as a serious shortcoming from the viewpoint of technology development. The effect of factors such as stand conditions
and hauling distances should be known for a number of reasons:
• to identify the most advantageous stands for chip production
• to estimate the change in the cost when the demand for chips increases or quality requirements of the
fuel are tightened
• to focus on the key problems in machine and method development
• to collect relevant material for practitioners for decision making.
128
The effect of cost factors associated with the operating environment depends on the scale of operation,
the technology applied, the source and quality requirements placed upon the biomass. At the end of the
fourth year of the programme, cost factor information is only available for logging residues from final
harvest, whereas cost studies on smalltree harvesting from early thinnings are still in progress. Examples
of the results are presented below:
• The cost of recovery depends on the yield of biomass per hectare. The recovery of logging residues
from the final cut of mature spruce stands is typically 20 % of the recovery of roundwood. For pine, the
corresponding figure is not much more than 10 %. Halving the recovery raises the cost of off-road transport by 10 %. The cost of harvesting is thus lowest in spruce-dominated stands, and the availability of
forest fuels is best in regions where spruce is the dominating species.
• The proportion of foliage in logging residues from mature stands in 30%for spruce and 20% for pine.
The cost of chips increases if the residues are left to season on the site so as to improve the quality of fuel
and reduce the loss of nutrients from forest soil through defoliation. The cost increase is caused by reduced biomass recovery, the delay in the harvesting schedule, and accompanied logistical disadvantages.
• If a plant’s demand for logging residues increases, the average cost of procurement increases as well,
because the operations must be extended to less favourable stands and at greater distances. Figure
82shows how the average cost of biomass at plant (cost of comminution excluded) increases with growing demand. Considerable regional differences result from differences in the structure of forests and
species dominance. Furthermore, a plant with a coastal location has to operate within a semicircular
procurement area, whereas plants in the interior typically operate within a circular procurement area.
Figure 82. Effect of a plant’s demand for logging residues on the average cost of transportation in different regions of Finland. Cost of comminution excluded. Source VTT.
• The small size of timber sales from private forest holdings is a serious cost factor. Proper timing and coordination of operations with neighbouring holdings could increase the harvestable fuel in a region by
more than 10 % and reduce the average costs by 4 to 6 %.
A3.4 Truck transport of forest chips
Truck transport is the largest single cost factor in the procurement of logging residue chips, constituting
up to one third of the total cost at the plant. As the use of forest fuels grows, the average distance and
the cost of transport will also grow further.
129
At present, forest biomass is delivered to the plant mainly in the form of chips. Most of the trucks used
for hauling forest chips were originally designed for operating on better roads and for other materials
such as sawmill chips, sawdust, debarking residues and peat. They are not ideal for use on forest roads
and cramped landing sites. The unsuitability of trucks strains the productivity because of slower driving
speed, increased waiting times and under-utilization of load capacity. Drivers of these trucks are often
unaccustomed to side roads and therefore reluctant to use them. Consequently, shortage of trucks is not
uncommon.
Along with the increase in the use of forest chips it has become necessary, but also easier, to employ
special trucks for forest chips or even uncomminuted residues, and to develop efficiency by means of
advanced logistic control of transport. The following topics have been studied in the programme:
• Compaction of chips to increase bulk density in conjunction with loading from the chipper. Compared
with blowing, a belt conveyor equipped with a mechanical ejector was found to compress the load volume by up to 15 %.
• Truck transport of uncomminuted loose residues (Figure 83) and residue bundles.
• Logistics of forest fuel transport. The use of an internet-based, general-purpose logistics control system
applying mobile terminals was studied. Among the aspects investigated were vehicle control and terminal logistics, navigation of vehicles, and work planning and instruction delivery by internet to mobile terminals.
There is considerable development potential in the logistics control system (Figure 84). The advantages
mentioned by the participants of the project under consideration are “paper free truck cabin”, decreased
need of cellular phone calls, and GIS/GPS supported navigation. Technology should be developed further to support the whole business process of the truck entrepreneur so that the information needed in
planning, operative work and invoicing could be monitored by the system.
Figure 83. Loading uncomminuted logging residues onto a special truck+trailer unit (Courtesy of
Metsäteho Oy).
130
Figure 84. Internet-based logistics control systems help to reduce the cost of chip procurement and improve the reliability of fuel supply (Courtesy of Biowatti Oy).
A3.5 Control of fuel quality
The quality of forest chips is dependent upon the source of the biomass and the techniques employed
for comminution, handling and storage. Consistent particle size, as well as low contents of moisture, foliage and ash each improves the efficiency and economy of combustion. However, different boilers demand different fuel properties. The larger the plant, the more tolerant it usually is of random variations in
fuel properties, mainly because large boilers employ the fluidized bed technology. Even so, knowledge
of fuel properties and careful control of quality are essential to the operational reliability and efficient
combustion of all boiler systems. The most important single quality factor is the moisture content of chips,
as it affects the heating value, storage properties and transport costs of the fuel. Moisture content is thus
a direct cost factor, and it is taken into account in the pricing of fuel. An excessive moisture content results in a price reduction, while a low moisture content may bring a bonus.
The moisture content of fresh biomass must be reduced to obtain the full energy potential. Moisture is a
critical fuel property, especially in the winter time (Figure 85), as a reduction in the moisture content occurs only during the summer. Maintaining the reduced level of moisture during the autumn rains requires careful planning and timing of operations. During recent years, the procurement organizations
have managed greater control of the moisture content, and truck loads of fuel with an excessive 55–60
% moisture content are no longer common. Nevertheless, energy is still lost because biomass arrives at
the plant with an excess of moisture.
131
Figure 85. Seasonal variation of the moisture content (green mass basis) of forest chips arriving at
plant in 2000. Average of several plants. Source VTT.
Forest chips that contain high quantities of needles may cause combustion problems because of their high
contents of alkali metals and chlorides. Depending on the combustion conditions, the alkali metals can
be oxidized or they can form sulphates or chlorides. If onlywood chips are burned, the sulphur content is
low and chlorides are formed. The chlorides tend to be condensed on heat transfer surfaces of the boiler
causing the risk of high-temperature corrosion. If the sulphur content of the fuel is increased, e.g. by mixing peat with chips, sulphates are formed instead of chlorides, and the risk of corrosion is avoided.
Unless the needle problem in combustion is solved, forest chips cannot be allowed to contain a high
needle content, which means friction in the logistics and increased costs. Therefore, this topic is given
considerable emphasis in the program.
Examples of the projects dealing with the quality yimprovement of forest chips in the Wood Energy Technology Programme, as well as quality aspects of industrial processing residues, are:
• quality control of logging residues and small diameter trees by means of seasoning
• critical properties of wood fuels in respect of power plant availability
• chemical changes in wood fuels during storage and thermal drying, and the effects of the changes on
fuel properties, occupational health hazards and emissions during storage
• flue gas emissions from cofiring by-products from the plywood and particle board industries
• boiler corrosion in conjunction with the cocombustion of wood and sludge
• improving the combustion properties of bark: reduction of moisture content prior to storage, removal
of impurities, and optimizing storage
• use of forest chips in large fluidized bed boilers
• improving the particle size of chips through chipper development
• suitability of small-diameter wood for pulping, and setting of boundaries between pulpwood and fuelwood.
A3.6 Receiving and handling forest chips
Wood fuels differ from peat and coal in respect of their handling properties, such as particle size, particle
size distribution, bulk density, moisture content and fluidity. Differences also occur amongst the wood
fuel. For example, forest chips and debarking residues behave differently as fuels.
Modern boilers, fluidized bed boilers in particular, make possible the efficient use of non-homogenous
forest fuels, and to cocombust them with other fuels. In large plants, forest chips are often blended with
bark and peat to homogenize and standardize the mixture.
Receiving, handling, mixing and feeding are problematic where the plant is not prepared for the special
properties of chips and chip truck. As these operations are an essential function of a forest fuel produc132
tion system, they are given an important position in the Wood Energy Technology Programme. The following topics are being addressed:
• Development of inbound logistics of arriving chip trucks in order to reduce the time used for queing
and unloading.
• Adjusting plants designed for peat trucks unloading sidewards to accept chip trucks unloading backwards.
• Making a homogenous mix from a variety of fuels. Mixing is usually performed at the receiving station
of the plant, but it may take place also in conjunction with intermediate fuel storage when loading or
unloading fuel silos.
• Adjusting handling equipment, such as disc screens and conveyors, to cope with chips containing oversized particles, impurities and excessive moisture.
• Developing comminution of forest biomass with high-capacity stationary crushers at the plant.
When old technology is replaced, or a Greenfield plant is built to use forest chips, participation of the
forthcoming chip procurement organization in the planning phase is necessary. Since the mid 1990s, a large
number of heating and CHP plants have been refitted with the technology required to use forest chips.
This has greatly increased the utilization capacity of forest fuels in Finland. It has been learned by experience, that due consideration must be given to the differing properties of forest chips and the specific demands of the forest fuel procurement system. Otherwise, the fluency of fuel deliveries, reliability of fuel
feeding and the quality of fuel may suffer.
A3.7 Impacts of biomass removal on forestry
The fundamental rationale for the promotion of forest energy is the reduction of greenhouse gas emissions, i.e. the protection of the environment. It follows that the production must be in agreement with sustainable forestry. Although the Wood Energy Technology Programme is primarily aimed at developing
new technology for forest chip production, the impacts on the ecosystem and forestry can not be ignored.
Studying the effects of intensive biomass removal requires long-term biological experiments and permanent sample plots in forests. This is beyond the scope of short-term technological projects. However,
credibility of the system development presupposes that its impacts are taken into account and evaluated. The goal must be prevention, or at least the minimization of possible harmful effects.
The greatest concentration of plant nutrient elements occurs in the parts of the tree, such as foliage,
where essential life processes take place. It is thus inevitable that the extraction of crown mass means an
increase in nutrient loss from the forest; more in fact than the increase in biomass yield would suggest.
In comparison with conventional stem-only harvesting, each percentage increase in biomass recovery
from crown mass with foliage incurs increased nutrient losses amounting to 2– 3 % for pine, 3–4 % for
spruce, and 1.5 % for leafless hardwoods. Yet, particularly in managed forests, crown mass represents such
a large proportion of
the fuel potential that large-scale bioenergy production would not be feasible without it.
Yield studies show a decline in growth after crown mass removal. However, scientific experiments carried out in Finland and other Nordic countries do not correspond to the every-day practice in the following respects: crown mass has been completely removed from the experimental stands, which would
never be achieved operationally; the growth loss caused by 4 m wide strip roads in thinnings has not
been taken into consideration; and in the control plots representing stem-only logging, residual biomass
has been distributed manually evenly across the whole site in an ideal way, which is not the real case in
mechanized cutting operations. Results from scientific experiments only seldom include allowances for
the differences between experimental treatments and actual harvesting practices, thus causing confusion among forest owners.
133
Even though the results may be exaggerated, the problem is real enough. The programme sees the control of nutrient loss to be an important aspect of the development of harvesting techniques. The following possibilities occur:
• No technology is able or intended to remove all crown mass from the site. For example, the salvage of
logging residues from the final harvest, irrespective of the system applied, extracts only some 70 % of
the crown mass.
• Summertime transpiration drying is an effective way of achieving the simultaneous reduction in moisture content and partial defoliation in small whole trees and logging residue heaps on the site. However,
the flow of fuel from the logging site to the energy plants slows down, and the recovery of biomass is
reduced.
• In small-tree operations, especially in young pine stands, topping the trees means compromising the
principle of whole-tree logging, but it reduces effectively the loss of nutrients. If a 3 m top from a pine
tree is left on the site in an early thinning, needle recovery is reduced by 52% but the overall recovery of
whole-tree chips is reduced by only 8 %.
• Nutrient loss caused by intensive biomass recovery can be counteracted by the recycling of ash, the loss
of nitrogen excluded. A precondition of feasible ash recycling is proper ash management at the plant.
Cofiring of biomass with fossil fuels, municipal waste or peat results in diluting the nutrient content of
ash and is therefore a serious constraint to recycling. So far, the programme has not developed ash recycling technology. But to assure the safe handling, storage and use of ash, an ongoing project is developing tools to predict the radioactivity of wood ash. A life cycle analysis of wood fuel use has also been carried out.
The negative effect of biomass removal on forest growth can be largely reduced by these means. From
the viewpoint of the forest owner, possible growth losses should be weighted against the silvicultural benefits achieved:
• Precommercial thinnings, the Achilles’ heel of the Finnish forestry, are encouraged. Tending young
stands results in the increased growth of industrial timber.
• The removal of logging residues from regeneration areas improves the productivity and quality of site
preparation and planting. A cost saving of € 100/ha may be achieved.
• The removal of logging residues and stumps creates favourable conditions for the mechanization of
planting. About 80 000 ha are reforested each year in Finland by manual planting, but a serious shortage
of forest labour is becoming an insurmountable barrier. The effect of biomass removal on the conditions
for mechanized planting is being studied in the programme.
134
135
Appendix 4.
Background
Finland is the world leader in utilisation of bioenergy and currently about 20% of the primary energy is
derived from wood-based fuels. Finnish forest industry has the central role in converting woodbased
residues into heat and power.
However, meeting the challenges of the mitigation of climate change has lead to the commitment to
double the use of the renewable energy sources by 2025, as compared to the situation in 1995. The main
focus is on wood-based bioenergy. The main source of wood-based fuels is processing residues from the
forest industries. However, as all processing residues are already in use, an increase is possible only as far
as the capacity and wood consumption of the forest industries grow. Energy policy affects the production and availability of processing residues only indirectly.
Another large source of wood-based energy is forest fuels, consisting of traditional firewood and chips
comminuted from low-quality biomass. It is estimated that the reserve of technically harvestable forest
biomass is 10–16 Mm3 annually, when no specific cost limit is applied. This corresponds to 2–3 Mtoe or
6–9 % of the present consumption of primary energy in Finland. How much of this reserve it will actually
be possible to harvest and utilize depends on the cost competitiveness of forest chips against alternative
sources of energy.
A goal of Finnish energy and climate strategies is to use 5 Mm3 forest chips annually by 2010. The use of
wood fuels is being promoted by means of taxation, investment aid and support for chip production
from young forests. Furthermore, research and development is being supported in order to create
techno-economic conditions for the competitive production of forest chips. The combustion capacity of
the present and planned heating and power plants is sufficient to absorb practically all competitively
priced woody biomass available. As a result of the recent technological development, even stump and
root wood can be used by large power plants equipped with modern fluidized bed technology.
Considerable progress is taking place in the technology of chip production, e.g. the successful CRL system based on bundling of residues and crushing at the plant. Nevertheless, the production of chips
rather than combustion technology still remains the real bottleneck for the utilization of the bio-mass
potential of the Finnish forests. The main barrier is the high price of chips.
Means to promote biomass based fuels
The objective of the Government’s energy policy is to create circumstances that ensure the availability of
energy, keep the price of energy competitive, and enable Finland to meet its international commitments
with respect to emissions into the environment.
Wood fuels becoming available from industrial processes depends directly on the future growth of the
forest industries. As a rule, using these by-products for energy is profitable, and the production technology is not a key issue.
Wood fuels derived directly from low-quality forest biomass. Here, the resource would enable an even
higher increase than that outlined, and the availability of the biomass is not connected with future
growth of the forest industries. Instead, a major barrier to the increased use of forest biomass as a source
of renewable energy is its poor price competitiveness in respect to other fuels. Consequently, the development and commercialization of innovative forest fuel production technology is essential.
However, as the demand for forest chips increases, availability starts to cause concern. In addition to developing technology and reducing costs, non-technical barriers must also be addressed in order to encourage forest owners, forest machine entrepreneurs and chip producers.
136
The Government’s aim is to make all forms of renewable energy economically competitive on the open
energy markets. The following support measures are employed:
• Energy taxation on fuels used for heat production
A carbon-based environmental fuel tax was imposed in 1990. Wood-based fuels are free of the tax because of their carbon neutrality.
• Support to electricity production
A tax of 6.9 €/MWh is levied on electricity, whether domestic or imported, rather than on fuel input. If
forest chips or wind are used for the production of electricity, the tax is refunded to the producer.
• Aid for investments
Financial aid can be granted to development and investment projects in order to promote the conservation of energy, to improve energy efficiency, to promote utilization of renewable energy, to improve the
security of energy supply, and to reduce harmful impacts of the production and use of energy. For special equipment used in the production of forest chips, the investment aid is typically about 20% of the
costs. Projects involving innovative technology are given priority.
• Support for the production of forest fuels
When small-diameter fuelwood is harvested from young forest stands, a subsidy of about 5.5 €/MWh is
paid to chip producers. The stands must meet specific silvicultural criteria. No direct support is awarded
for the production of fuel chips from logging residues from late thinnings or final harvest.
• Public financial support to development and commercialization of technology
The National Technology Agency, Tekes is responsible for technology R&D funding. Tekes allocates annually 10 million euros to the RES sector. The Ministry of Trade and Industry gives financial support to
demonstration projects.
The main R&D programmes on bioenergy include:
A) Bioenergy Research Programme (1993–1998), which was aimed at the production, use and conversion of wood and peat fuels in 1993–1998.
B) Wood Energy Technology Programme (1999–2003), that is focused on the development of technology for the large-scale production of forest chips.
The availability of forest biomass is not a limiting factor since the potential greatly exceeds the target.
The capacity of heating and power plants also soon exceeds the target: new wood fuelled plants have
been established and old plants have been modified to receive, handle and burn chips. The real limiting
factor is the production of chips at competitive cost.
The ultimate target of the Wood Energy Technology Programme is to create favourable conditions for
increasing the use of forest chips. Consequently, the programme is aimed at developing the production
technology and procurement logistics for forest chips. The emphasis is on system development for largescale operations in conjunction with combined heat and power production.
Preconditions for a rapid increase in the use of forest chips are the reduction of costs, improved quality
of chips, and reliable delivery systems. Chips must also be produced by environmentally sound methods
that support sustainable forest management.
The primary targets of the programme are:
•to integrate energy production into conventional forestry and the procurement of industrial timber
• to develop production systems and procurement logistics for forest fuels
137
• to develop technology for comminuting, bundling, handling and storage of wood fuels
• to develop long-distance transport of chips, uncomminuted loose residues and composite residue logs
• to encourage the participation of forest machine and truck contractors in the wood fuel branch
• to develop quality control for forest chips and processing residues from the forest industries
• In 2002 the scope was expanded. A sub-programme was established for small-scale production and
combustion of wood fuels.
The programme has set for itself an unofficial goal: increasing the annual use of forest chips from 0.5
Mm³ in 1998 to 2.5 Mm³ in 2003. Unofficial statistics show that the use of forest chips was about 2 Mm3
in 2003.
The organization of the R&D programme
The programme is composed of projects that typically last 1–3 years. There are three types of projects:
• Projects undertaken by research institutes address common and general needs. The results and knowhow achieved are in the public domain. In research projects research organizations collaborate with industrial partners.
• Projects dealing with product development, i.e. industrial projects, are related to practical applications.
They serve specific needs of a single company or company integrate. Examples include the development
of a complete chip procurement system, a less corrosive combustion technique for chips rich in needles,
or a chipper, bundler, feller-buncher for small trees, forwarder for biomass transport, and a special truck
for forest fuels. An industrial project commonly includes a research component that requires cooperation with a research organization. The results and experience from company projects are not necessarily
in the public domain.
• Demonstration projects are aimed to promote introduction and deployment of new technologies in forest fuel production and combustion. Funding is primarily investment grant-aid from the Ministry of
Trade and Industry.
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Appendix 5
Current (2003) Technical Biomass-based fuel availability
-Future (2010) Technical Biomass-based fuel availability
139
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
140
GWh fuel
250
300
350
MONEYPOINT, Technical biomass-based fuel availability, 2003
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
500
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
141
GWh fuel
250
300
350
EDENDERRY, Technical biomass-based fuel availability, 2003
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
500
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
142
GWh fuel
250
300
350
WEST OFFALY, Technical biomass-based fuel availability, 2003
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
500
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
143
GWh fuel
250
300
350
LOUGH REE, Technical biomass-based fuel availability, 2003
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
500
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
144
250
GW h fuel
300
350
MONEYPOINT, Technical biomass-based fuel availability, 2010
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
W ood Pellets
SRC W illow
500
KESKENERÄINEN
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
145
250
GWh fuel
300
350
EDENDERRY, Technical biomass-based fuel availability, 2010
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
SRC Willow
500
KESKENERÄINEN
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
146
250
GWh fuel
300
350
WEST OFFALY, Technical biomass-based fuel availability, 2010
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
SRC Willow
500
KESKENERÄINEN
€/MWh fuel
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
0
50
100
150
200
147
GWh fuel
250
300
350
LOUGH REE, Technical biomass-based fuel availability, 2010
400
450
Sawchips
Sawdust
Bark
Pulpwood
harvesting residues
Straw
Tallow
Meat and Bone Meal
Spent Mushroom Compost
Chicken Litter
Wood Pellets
SRC Willow
500
KESKENERÄINEN
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