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RWEDP Report No. 29
REGIONAL WOOD ENERGY DEVELOPMENT PROGRAMME IN ASIA
GCP/RAS/154/NET
Energy and Environment Basics
Compiled in co-operation with
Technology and Development Group
University of Twente, Netherlands
2nd edition
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
Bangkok, July 1997
This publication is printed by
the FAO Regional Wood Energy Development Programme in Asia,
Bangkok, Thailand
The designations employed and the presentation of material in this publication do not imply
the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United nations concerning the legal status of any country, territory, city or area or
of its authorities, or concerning the delimitations of its frontiers or boundaries.
The opinions expressed in this publication are those of the author(s) alone and do not imply
any opinion on the part of the FAO.
For copies write to:
Regional Wood Energy Development Programme in Asia
c/o FAO Regional Offcie for Asia and the Pacific
Tel: 66-2-280 2760
Maliwan Mansion, Phra Atit Road,
Fax: 66-2-280 0760
Bangkok, Thailand
E-mail: [email protected]
FOREWORD
Discussing energy problems without using adequate concepts and proper terminology,
dimensions and units, makes as little sense as disregarding the universal laws of nature. It is
virtually impossible to make a sensible contribution to energy development without reference to
quantitative issues. This is well understood by scientists and engineers, but there are many
more disciplines to contribute to the diverse problems of energy development. The same
applies to some extent to issues of the (natural) environment. Also wood energy development is
a science-based subject, for which contributions from many different disciplines are needed.
The present document aims to be of assistance to those who work in the field of energy and
related aspects of environment, but do not have their education in science or engineering. It is
not a compendium for specialists. It may rather serve as a basic training and reference
material.
The document has been prepared in cooperation with the Technology and Development Group
of the University of Twente in the Netherlands. Inputs and overall editing were provided by Jaap
Koppejan, Associate Professional Officer at RWEDP, with assistance from other RWEDP staff.
In due course, RWEDP aims to prepare a document on 'Wood Energy and Environment Basics'
which may even more specifically serve those involved in developing wood and other biomass
energy. Comments and suggestions from readers will be welcome.
In the mean time it is hoped that the present document will serve a large audience. More copies
can be requested from RWEDP.
Dr.W.S. Hulscher
Chief Technical Adviser
Regional Wood Energy Development Programme.
1
TABLE OF CONTENTS
Foreword ................................................................................................................................... 1
1.
2.
3.
4.
2
Basic Introduction to Energy ....................................................................................... 4
1.1
Energy Forms and Conversions .......................................................................... 4
1.2
Energy and Power ............................................................................................... 5
1.3
Dimensions and Units of Energy and Power........................................................ 6
1.4
More on Energy Conversions and Efficiency ....................................................... 7
1.5
Energy Flows..................................................................................................... 10
1.6
Primary Energy Sources.................................................................................... 12
1.7
Energy Terminology .......................................................................................... 13
Basic SI Units, Prefixes, and Derived SI Units Used ................................................ 15
2.1
Basic SI Units .................................................................................................... 15
2.2
SI Prefixes ......................................................................................................... 15
2.3
Most Common Derived SI Units......................................................................... 16
2.4
Conversion of Non-SI Units to SI Units .............................................................. 16
Energy Accounting ..................................................................................................... 23
3.1
Equivalence and Replacement Values .............................................................. 23
3.2
Energy Balances ............................................................................................... 24
3.3
Energy Auditing ................................................................................................. 27
General Energy Data ................................................................................................... 29
4.1
World Energy Production and Consumption ...................................................... 29
4.2
Biomass Energy Consumption in RWEDP Member Countries........................... 33
5.
Fuels and Combustion................................................................................................ 35
5.1
Chemical Composition....................................................................................... 35
5.2
Moisture Content ............................................................................................... 36
5.3
Ash Content....................................................................................................... 38
5.4
Heating Values .................................................................................................. 39
5.5
Bulk Density....................................................................................................... 41
5.6
Fuel Characteristics ........................................................................................... 43
6.
Wood Production Figures .......................................................................................... 44
7.
Electricity Production and Consumption .................................................................. 46
8.
Transportation............................................................................................................. 54
9.
Energy Intensity .......................................................................................................... 55
10.
Greenhouse Gases ..................................................................................................... 56
11.
Air Emission Standards.............................................................................................. 58
12.
Glossary of Energy and Environmental Terms ......................................................... 71
3
1. BASIC INTRODUCTION TO ENERGY
It is not unusual to hear colleagues, friends or family members say “I’ve got no energy today!”
when they don’t feel up to completing an assignment, playing sport or washing the dishes. This
everyday expression is actually very close to the scientific definition of energy. Energy is the
ability (or capacity) to do work. The word “work” here, to a scientist or engineer, has a much
broader meaning than simply going to the office or factory. However, non-technical people can
still think of energy as the ability to do all the hundred and one diverse things we might need or
want to do in our daily lives, from switching on a light to building a house.
Energy itself is not a thing or substance but an idea, a theoretical concept, used to connect
diverse processes, such as burning fuels, propelling machines or charging batteries, and to
explain various observations about these processes. Central to the concept of energy is that
processes which might at first sight appear to be very different, like those referred to in the
previous sentence, actually have a number of common features. Describing these common
features leads us to a greater understanding of what energy is.
1.1 Energy Forms and Conversions
A basic concept about energy is that while it has many forms (see Box 1.1), and can be
converted from one form to another (though some of the conversions would have no practical
value) or transformed from one grade of the same energy form to another (for example from
high temperature heat to low temperature heat), it can never be “used up”, and the actual
amount of energy stays the same. This is the basis of the First Law of Thermodynamics: in
any process involving energy,
the total quantity of energy is
BOX 1.1 FORMS OF ENERGY
Kinetic energy: energy possessed by a moving object, such as conserved.
wind or water in a stream. Speed and mass of the object influence
the amount of kinetic energy. The faster the wind blows or the
more water flowing in a stream the more energy is available.
Potential energy: energy possessed by an object’s position
relative to the earth’s surface. This is stored energy which if the
object falls is converted into kinetic energy. For example, water
behind a dam: the higher the dam or the greater the amount of
water, the higher the potential energy.
Thermal energy (heat): A form of kinetic energy due to the
random motion of the atoms or molecules (the building blocks) of
solids, gases or liquids. The faster the atoms or molecules move,
the greater the thermal energy of the object, usually described as
the hotter the object is.
Chemical energy: A form of energy stored in atoms or molecules.
This energy is usually utilised by converting into heat (combustion)
or electrical energy (batteries).
Electrical energy: Most familiar in the form of electricity, which is
the organised flow of electrons (one of the building blocks of an
atom) in a material, usually a metal wire.
Electromagnetic energy (radiation): A form of electrical energy
which all objects, in different amounts, emit or radiate. The most
familiar forms are light and sound.
Mechanical energy: The energy of rotation usually associated
with a rotating shaft.
4
However,
from
our
observations of normal life, we
know that in practical terms,
energy does run out. Batteries
in, for example, a torch
eventually
stop
producing
electrical energy and have to
be replaced. What has actually
happened is that the torch’s
bulb
has
converted
the
electrical energy into light – the
energy form it is designed to
produce – and, to a large
extent, waste heat. The original
chemical energy stored in the
battery has not disappeared, it
has just radiated into the
environment, where we can no
longer make use of it. The
energy may be lost to the
system (the torch and battery),
but the total amount of energy is the same before and after. It should be noted here that we
tend to focus on the energy form we want (the useful energy – the light in our example) and
regard the other as wasted (the heat), and so we neglect or overlook it. This can be an
expensive mistake, and energy conservation efforts pay a lot of attention to reducing the size of
this waste.
Energy conversions are just the ways in which we harness and utilise energy. For example, we
convert the potential energy of water stored in a dam into the mechanical energy of a turbine,
which in turn is converted into electrical energy. To pump water up from a well we do the
reverse. In everyday English we talk about “generating” and “consuming” energy, especially
when discussing electricity. These are, in fact, scientific impossibilities – what we are actually
describing is converting one form of energy to another. By generating electricity we usually
mean converting the chemical energy stored in a fuel such as coal or oil, by combustion into
heat energy, which in turn is converted into the mechanical energy of a turbine, and then into
electricity. What we in fact consume are fuels, which are forms of stored chemical energy.
1.2 Energy and Power
When utilising an energy conversion we are usually concerned with two things: the quantities of
energy involved and the rate at which energy is converted from one form to another, or
(particularly in the case of electricity) transmitted from one place to another via a medium, such
as water or high-voltage cable. The rate per second at which energy is converted or transmitted
is called the power. Thus there is a mathematical relation between the two concepts:
energy = power x time
or
power =
energy
time
In qualitative terms, this means that if you have a given quantity of energy, the greater the rate
at which you use it, the larger the amount of power produced. Take, for example, the chemical
energy stored in a tank of petrol, which, by a
succession of conversion processes, eventually
becomes the kinetic energy of the moving car. BOX 1.2 RELATIONSHIP BETWEEN
The more petrol allow into the engine per intake ENERGY AND POWER
stroke (by depressing the accelerator), the more At what rate per hour does a 1 kW heater
power the engine will produce and the faster the convert electrical energy into heat?
car will move. Another way to look at this is that the
more power you want from the engine, the quicker energy = power x time
1 kW is 1,000 watts
you will use up the fuel.
In everyday English, the words “power” and
“energy” are often used interchangeably. If the
meaning is clear in the context, then a lack of
scientific accuracy is not a problem. However, in
energy planning it is vitally important you are clear
which you mean.
When describing energy conversions, the energy
resources undergoing transformation are usually
characterised in terms of their quantities, and the
conversion equipment in terms of the amount of
Since 1 watt is 1 joule per sec
1,000 watts is 1,000 joules per sec
In one hour there are 3,600 seconds
Substituting in the equation
energy = 1,000 x 3,600 joules
= 3,600,000 joules
= 3.6 MJ
Therefore a 1 kW heater converts 3.6 MJ of
electrical energy into heat per hour.
5
power it consumes or produces. The next section looks at energy and power in quantitative
terms.
1.3 Dimensions and Units of Energy and Power
There are many ways of measuring energy, and although most scientists internationally use the
same unit, the joule (abbreviated as J), it is quite common to find other units in everyday use.
Americans and many engineers, particularly when
talking about steam, use British Thermal Units
(abbreviated as BTUs), and in India the calorie BOX 1.3 NON-ELECTRICAL ENERGY UNITS
A boiler consumes half a cubic metre of natural
(abbreviated as cal) is still common. National gas in one hour. What is the power input?
energy statistics use tonnes of coal equivalent or
barrels of oil equivalent. It is possible and, for The heat energy content of natural gas is 38
comparisons, desirable to convert the different MJ per cubic metre. Therefore in one hour the
units from one to the other, and Chapter 2 boiler has converted 19 MJ of heat energy
contains tables which give the appropriate factors
power = energy/time
to make these conversions.
Power is almost universally measured in watts
(abbreviated as W). 1 watt is defined as the power
produced when converting 1 joule of energy per
second, which can be written as 1 J/s (or 1 J s-1)
(see Box 1.2 for a worked example). 1 joule and 1
watt are very small quantities compared to the
amounts converted in many types of equipment, so
it is quite common to use multiples of ten for both
quantities (for example 103 J; 106 W) or to
abbreviate the powers of 10 with prefixes, for
example kilowatt (1 kW = 103 W), megawatt (1
MW = 106 W), kilojoule (1 kJ = 103 J) and
gigajoule (1 GJ = 109 J)
Many electrical appliances are sold in terms of their
power rating, for example a 60 W light bulb or 1
kW hot plate. It is therefore very common to
measure electrical energy consumption (i.e.
conversion) in terms of power and time. For
example, a one kilowatt device running for one
hour uses 1 kilowatt-hour (kWh), which is 3.6 MJ,
of energy.
= 19/3,600
= 5,300 joules per second
= 5.3 kW
BOX 1.4 MAGNITUDE OF 100 KJ OF ENERGY
100 kJ of energy is equivalent to:
⇒ radiation from the sun falling on the roof of
2
a house (of about 40 m ) in 2.5 s
⇒ heat released on burning 3.5 g coal or 2.9 g
petrol
⇒ potential energy of object (1,000 kg) at a
height of 10 m
⇒ energy captured by a windmill of 3 m
diameter in 20 mins in a wind blowing at 5
m/s
⇒ energy stored in a car (1,000 kg) moving at
50 km/h
⇒ heat emitted when 3 cups of coffee (0.4 kg)
cools from 80EC to 20EC
⇒ energy needed to melt 0.3 kg of ice
⇒ electrical energy consumed by 100 W light
bulb in 17 minutes
⇒ rotation energy of flywheel 0.6 m diameter,
70mm thick rotating at 1,500 revolutions
per second
The form of the energy can also be distinguished in
the output from a particular piece of equipment.
For example, a steam turbine produces both thermal and mechanical energy that can be used
by the equipment coupled to it. When it is not clear from the context, a subscript can be added
to the abbreviation to indicate what form of output energy we refer to: thermal energy – kWth;
electrical energy – kWel; mechanical – kWm. Non-electrical energy conversion processes can
also be described in terms of power. (see Box 1.3 for a worked example.)
6
The joule and the watt belong to the international system known as SI units. A list of the
common SI units is given in Chapter 2.
It is important not only to be able to make
quantitative comparisons about energy but
also to have an appreciation of the
magnitudes of energy, in its different
forms, and of power. Box 1.4 gives some
representative examples of energy while
Box 1.5 shows some comparative orders
of magnitude of power and energy.
1.4 More
on
Energy
Conversions and Efficiency
BOX 1.5
POWER
ORDERS OF MAGNITUDE OF ENERGY AND
1 kWh Roughly energy consumed by electric hot plate
in one hour
1 MWh Roughly energy needed to drive a car
1000 kilometres
25 TWhRoughly energy demand in Philippines in 1991
1 kW Power rating of an air conditioner
10 kW Power rating of small tractor/power tiller
1 MW Rated output of power station serving a small
town of around 20,000 people.
It was noted above that when one form of energy is converted into another for a particular
purpose, not all the energy ends up where you would like it, and energy is wasted or lost to the
process. This loss is usually in the form of heat. The ratio of the useful energy output to the
required input is the efficiency of the process – the higher the efficiency, the less energy is
“lost”. Efficiency is represented by the Greek letter η and is usually expressed as a percentage.
Energy input
Convertor
Useful energy
Losses
The efficiency of an energy conversion process is never 100%. It can be as high as 90% (for
example in a well-run water turbine) or very much less than that (for example 10–20% in a
typical internal combustion engine). Inefficiency can be reduced by good equipment design and
use, but some is inherent in the nature of the energy conversion, and an understanding of these
inherent inefficiencies is the key to optimising energy use. Some typical conversion efficiencies
are given in Table 1.1.
7
Table 1.1 Typical conversion efficiencies of different energy conversion technologies
converter
petrol engine
diesel engine
electric motor
boiler and turbine
hydraulic pump
hydro turbine
hydro turbine
generator
battery
solar cell
solar collector
electric lamp
water pump
water heater
lpg stove
wood stove
charcoal stove
charcoal kiln
form of
input energy
chemical
chemical
electrical
thermal
mechanical
potential
kinetic
mechanical
chemical
light
light
electrical
mechanical
electrical
chemical
chemical
chemical
chemical
form of
output energy
mechanical
mechanical
mechanical
mechanical
potential
mechanical
mechanical
electrical
electrical
electrical
thermal
light
potential
thermal
thermal
thermal
thermal
chemical
typical
efficiency
20-25 %
30-45 %
80-95 %
7-40 %
40-80 %
70-99 %
30-70 %
80-95 %
80-90 %
8-15 %
25-65 %
5%
60 %
90-92 %
60-70 %
12-30 %
20-30 %
25-40 %
Box 1.6 HEAT AND TEMPERATURE
Heat is thermal energy due to the motion of atoms or molecules. When an atom or molecule collides with
another of lower, energy a transfer of kinetic energy takes place which is always from the faster (hotter) to
the slower (cooler). This flow of heat enables a scale of relative “hotness” to be defined, which is what is
meant by “temperature”.
There are a number of different temperature scales. The SI scale used by scientists takes the starting point
of zero as the point when molecules have no motion. The unit of temperature on this scale is the Kelvin
(abbreviated to K). The most common scale in daily use is the Celsius scale (written as EC), in which zero
corresponds to the freezing point of water.
Values on the two scales can be easily converted from one to another using the formula:
temperature (K) = temperature (EC) + 273
Another scale still used by many people is the Fahrenheit (written as EF). This is converted into the Kelvin
scale as follows:
temperature (K) = 5/9F + 255
A Fahrenheit temperature is converted into a Celsius temperature by first subtracting 32 and then
multiplying by 5/9.
A Celsius temperature is converted into a Fahrenheit temperature by first multiplying by 9/5 and then
adding 32.
8
Figure 1.1 Efficiency of an energy conversion system
fuel
Diesel engine
30%
Generator
80%
Electric motor
80%
Water pump
60%
water
Overall system efficiency = 30% x 80% x 80% x 60% = 12%
The process of converting the form of energy input to the final output form generally comprises
a number of intermediate transformations or conversions. There are five conversion stages in
the diesel-powered water pump system shown in Figure 1.1: the chemical energy of the fuel is
converted, by the diesel engine, into mechanical energy to turn a shaft which the generator
converts to electrical energy. An electric motor converts the electrical energy back to
mechanical energy in the pump and the pump raises the water to the surface, and in so doing
transforms the mechanical energy into the potential energy of the water. Each stage in the
process has its own conversion efficiency and the overall system efficiency is found by
multiplying the efficiencies of the individual stages.
Clearly, the more stages there are in a conversion process the lower is the overall system
efficiency. This means not only a loss of useful energy, but a financial cost as well, so an
energy conversion system should generally be designed with as few stages as possible.
Another way to get round the problem, is to harness the waste heat from one stage and use it
elsewhere. For instance, the exhaust gases from a boiler in an agro-processing factory, which
usually contain a substantial amount of heat energy, can be used, via a heat exchanger, to dry
the product. By reducing both wasted heat energy and the requirement for input energy at the
drying stage, this increases the overall energy efficiency of the system.
This idea is the basis of co-generation or combined heat and power (CHP), where the waste
heat from electricity generation is used as process heat in a factory. A good example is the
sugar industry – in many cases, the factory generates its own electricity using a turbine (which
is often coupled to a boiler using the crushed sugarcane fibres, or bagasse, as fuel). Rather
than allowing it to run off into the atmosphere, the heat remaining in the exhaust gases is used,
via a heat exchanger, to evaporate water out of the raw cane juice, an essential part of the
extraction process. The overall efficiency of a co-generation system can be 80% or higher.
Using the energy of the original source for two or more applications is known as cascading,
where the grade of energy required is closely matched to the available energy.
Yet the efficiency of an energy conversion process depends not only on the equipment used,
but also on the form of the input energy. Some forms can be converted more efficiently than
others. This is related to their actual potential to do work (or exergy). The higher the exergy
content of an amount of energy, the more easy it is to do a certain task. For example boiling a
cup of water with 10 MJ of heat at 1000 EC will be much easier than boiling the same cup of
water with 10 MJ of heat at 110 EC. After any conversion process, the exergy or ability to do
useful work is less than it was before the conversion, either due to energy losses or quality
degradation.
9
Chemical energy, kinetic energy
Box 1.7 POWER STATIONS AND WASTE HEAT: A SECOND LAW
of
moving
matter,
stored
ANALYSIS
potential energy and electrical The Second Law of Thermodynamics can be expressed as an
energy can be shown to have an equation, which can be used to calculate the maximum theoretical
exergy content equal to 100% of efficiency of a conversion process where heat energy is converted
their energy, so conversion to to mechanical or electrical energy. Steam turbines used in many
lower energy forms can easiliy fossil fuelled power stations are heat engines. The efficiency
be realised easily with only small depends upon the temperature of the steam reaching the turbine
energy losses. Below them are and the lower temperature of the steam leaving to be condensed. If
high temperature heat and then these are called TU and TL respectively then:
low temperature heat with less
maximum theoretical efficiency = (Tu-TL)/Tu)
than 100% exergy content in the
energy. Since during any (The Kelvin temperature scale must be used in the formula.)
conversion
process
exergy
content can at best remain If steam enters the turbine at 550 oC and is ultimately cooled to 27
constant, the conversion from a oC the maximum thermodynamic efficiency is given by:
lower grade energy form such as
low temperature heat, to a Inserting the values
TU = 550 + 273 = 823 K
higher-grade energy form such
TL = 27 + 273 = 300 K
as electricity is inherently
into the formula gives:
inefficient. The efficiency of
(823 - 300)/823 = 0.635 or 63.5%.
electricity generation using a
steam or gas turbine is limited to In practice the best steam turbines achieve around 66% of the
about 40% since exergy is lost theoretical maximum efficiency which means that the actual
during fuel combustion that efficiency is likely to be: 0.66 x 0.635 = 0.42.
cannot be retrieved in the To obtain an overall system efficiency the turbine efficiency needs
turbine.
Present
research to be combined with boiler and generator efficiencies, both of
therefore focusses on increasing around 88%:
0.88 x 0.42 x 0.88 = 0.33 or 33%
the
turbine
operating
temperatures. It stands to
reason that the use of difficult to produce, high grade energy carriers such as electricity to fullfil
a low-grade energy demand such as boiling water should be avoided as it is irrational and
expensive. Though maybe less convenient, it would be more efficient and cheaper to boil the
water directly with gas.
Box 1.7 gives an example of an energy efficiency analysis based on the Second Law of
Thermodynamics.
1.5 Energy Flows
It was remarked earlier that energy conversions from the original source to the useful form
often take place in a number of intermediate stages. The energy flows from one form to another
at each conversion, transformation or transport step, and these steps can be considered as a
chain. Constructing such a chain enables an energy analyst to look at the efficiencies of the
different stages in order to reduce costs and avoid unnecessary losses.
10
Natural resources
Losses
Mining, drilling,
harvesting, collecting
Primary energy
Losses
Processing, conversion,
tranformation
Secondary energy
Losses
Transportation, transmission,
storage. distribution
Final energy
energy supply
energy demand
End-use device
Losses
Useful energy
Figure 1.2 The energy chain
When constructing the chain, energy is
classified into four types: primary,
secondary, final and useful. Primary
energy is the energy in the form in which it
is available in the natural environment.
Secondary energy is the energy ready for
transport or transmission. Final energy is
the energy which the consumer buys or
receives and useful energy is the energy
actually required to perform the work. To
illustrate the difference between final and
useful energy, consider a light bulb: the
final energy of the process enters the bulb,
but most is wasted as heat. The useful
energy, the light, may represent less than
10% of the final energy. This example
aside, useful energy is almost always in the
form of heat or mechanical shaft energy.
For or a few end uses, for example,
communications equipment, electricity is
the useful form.
An example of an energy flow or chain is the use of water to run a saw mill. The primary energy
is potential energy stored in the water in a dam. The water is used in a hydro power station,
where the potential energy is converted to electricity – the secondary energy. The electricity is
transmitted to the saw mill, where it is converted to the useful form of shaft energy. In this case,
the secondary and final forms are the same.
Figure 1.2 illustrates the concept of the chain and Figure 1.3 gives an example of a typical
energy chain for fuelwood.
Traditional
cookstoves
(Direct)
combustion
Natural
forests
Pyrolysis
Homestead
trees
Fuelwood
Community
trees
Wood
Plantations
Gasification
Household cooking,
water and space heating
Industrial heat
Charcoal
Household lighting,
electrical appliances
Low energy
gas
Electricity
generation
Hydrolysis/
fermentation
Improved
cookstoves
Water pumping
Electricity
Industrial applications
Biogas
Household lighting
Ethanol
Petrol/diesel engines
Figure 1.3 A possible energy chain for fuelwood
11
1.6 Primary Energy Sources
The previous section referred to primary energy sources as energy as it is available in the
natural environment. These include:
Biomass energy: any material of plant or animal origin such as woody biomass (stems,
branches, twigs) non-woody biomass (stalks, leaves, grass), agricultural residues (rice husk,
coconut shell), and animal and human faeces. The energy can be converted through a variety
of processes to produce a solid, liquid or gaseous fuel. The biomass usually needs some form
of processing stage prior to conversion, such as chopping, mixing, drying or densifying.
Solar energy: energy from the sun comes as either direct radiation or diffuse radiation.
Direct radiation is only collected when the collector (e.g. a leaf or a solar panel) faces the sun.
Diffuse radiation comes from all directions and is even present on a cloudy day. The energy
falling on a surface of a specified area is less for diffuse radiation than direct radiation. Solar
energy can be converted through thermal solar devices to heat, or through photovoltaic cells to
electricity.
Hydro energy: utilises the potential energy from water stored behind dams, weirs or natural
heads (water falls) and the kinetic energy of streams or rivers. Water wheels and hydro turbines
are used to convert this energy source to mechanical or electrical energy.
Wind energy: the kinetic energy from the wind is converted by wind turbines (also known as
wind generators or windmills) into mechanical energy (usually for water pumping) or electrical
energy.
Geothermal energy: heat flow from the earth’s core to the surface by molten rock or hot water.
The heat can be used for space heating, drying, process heat applications or electricity
generation.
Animate energy: energy delivered by humans and animals. This is a major source of energy
in agriculture in many developing countries, but never appears in national energy balances.
Ocean energy: includes three energy sources: wave and tidal, which both utilise the kinetic
energy of moving water, and ocean thermal, which utilises the heat flow between the warm
surface waters and cool deep waters of tropical oceans. All three are still at early stages of
development, but the intention is to use them to generate electricity.
Fossil fuels: Coal, crude oil and natural gas. The main commercial fuels around the world.
Nuclear energy: energy released when the nuclei of atoms (usually uranium) break apart. This
energy is utilised by converting it into electrical energy.
Although these sources are called primary, with the exceptions of solar, nuclear and tidal, they
are not ultimate sources of energy. The remainder are come, either directly or indirectly, from
solar energy.
12
1.7 Energy Terminology
Energy sources are sometimes classified under headings such as renewable, traditional,
modern, commercial and conventional. The terminology is rather ambiguous, since it depends
very much on the context. For example, wind energy is clearly renewable, but is it traditional?
Windmills have been used for several centuries, making it traditional, but wind has been used
to generate electricity only in this century, so perhaps it is modern. In different areas of a
country a source may be classified differently. For example, fuel wood in rural areas is often
non-commercial, whereas in towns it generally has to be bought. Table 1.2 shows the
classification of a number of energy resources according to three criteria: familiarity (that is,
conventional, traditional and non-conventional), renewability (renewable or non-renewable) and
monetisation (commercial and non-commercial).
Renewable means that a source is not depleted by use – wind is always renewable, while
biomass can be renewable if regrowth is matched by consumption. Fossil fuels are nonrenewable, as they will eventually be depleted (i.e. run out) as there is no viable way to produce
more of them. Another classification, new and renewable, covers all the renewable forms of
energy plus ocean and geothermal. Some energy analysts also include nuclear energy in this
category, though clearly not because it is renewable.
Whether an energy resource is traditional or non-traditional depends very much on the user’s
perspective. Many biomass users would be regarded as using a traditional source (that is, what
they have always used) and they would regard using fossil fuels as non-traditional. However, it
can be the conversion technology rather than the resource which determines the classification.
Wood can be regarded as a traditional energy resource, but if it is used in a gasifier it produces
a non-traditional energy source. Similar difficulties arise when categorising energy sources as
conventional and non-conventional.
Commercial energy refers to those energy sources for which have to be paid for. This always
includes the fossil fuels and some new and renewable sources. Biomass is usually classified as
non-commercial – however, this depends again on where you are in the world.
Table 1.2 demonstrates that a fuel can be placed in more than one category and that there are
no hard and fast rules. Classification depends on circumstances, and an energy analyst should
be prepared to exercise some flexibility and make clear what fuel classification is being used.
13
Table 1.2 Energy supply terminology by different classifications
Familiarity
Resource
Large scale hydropower
Coal
Oil and gas
Nuclear
Fuelwood
Agricultural residue
Animal dung
Animal labour
Industrial waste
Solar thermal
Solar photovoltaic
Wind
Small-scale hydropower
Biogas
14
Conventional
♦
♦
♦
♦
♦
Traditional
Reproducibility
NonConventional
Renewable
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
NonRenewable
♦
♦
♦
♦
Monetisation
Commercial
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
NonCommercial
♦
♦
♦
♦
♦
♦
♦
2. BASIC SI UNITS, PREFIXES, AND DERIVED SI UNITS USED
2.1 Basic SI Units
Basic Unit
Unit
Abbreviation
length
metre
m
mass
kilogram
kg
time
second
s
electric current
ampere
A
Kelvin
K
temperature
2.2 SI Prefixes
Prefix
Abbreviation
Factor
exa
E
1018
peta
P
tera
Prefix
Abbreviation
Factor
deci
d
10-1
1015
centi
c
10-2
T
1012
milli
m
10-3
giga
G
109
micro
µ
10-6
mega
M
106
nano
n
10-9
kilo
k
103
pico
p
10-12
hecto
h
102
femto
f
10-15
deca
da
101
atto
a
10-18
15
2.3 Most Common Derived SI Units
#
*
name
unit
abbreviation
area
square metre
m2
volume (contents)
cubic metre
m3
speed
metre per second
m/s
acceleration
metre per second squared
m/s2
frequency
hertz
pressure
Pascal
volume flow
cubic metre per second
3
m /s
mass flow
kilogram per second
kg/s
density (specific mass)
kilogram per cubic metre
force
Newton
energy/heat/work
joule
J (= N.m)*
power/energy flow
watt
W (=VA=J/s)
energy flux
watt per square metre
W/m2
calorific value (heat of combustion)
joule per kilogram
J/kg
specific heat capacity
joule per kilogram per Kelvin
voltage
volt
Hz (= s-1)
Pa (= N/m2)
kg/m3
N (= kg.m/s2)#
J/kg K
V (= W/A)
A mass of 1 kg exerts a force of approximately 10 N (Exact value depends on position on
earth since force = g N, where g is acceleration due to gravity. g is 9.781 m/s2 at the equator.)
The joule can also be written in the form watt second (1 J = 1 W.s)
NB In many calculations, the symbol B (pi) is used. B is the ratio of a circumference of a circle
to its diameter and can be represented by the value 3.14159 (although in many instances
3.14 would be sufficiently accurate).
2.4 Conversion of Non-SI Units to SI Units
Although scientists and engineers must be strict in their use of SI units for their calculations, in
the every day world a number of non-SI units are still commonly used. Manufacturers of small
scale energy equipment are no exception. For example, engines are still sold by cc (cubic
centimetres of fuel-holding capacity) and hp (horse power), and water pumping windmill
manufacturers often quote in terms of cubic feet of water pumped per hour. Even among
16
manufacturers of the same type of equipment, consistency in the use of units is lacking.
Therefore, in order to be able to compare the products of different manufacturers, it is important
to be able to convert the different data to a common unit. The tables below give useful
conversion factors for some common non-SI units. The conversion ratios given in the tables
below can be used to convert the unit in the left-hand column to the unit in the top row, above
the ratio. (For example, 1 inch = 25.4 mm, while 1 mm = 0.0394 inches.)
length
unit
abbreviation
millimetre
mm
metre
m
kilometre
km
inch
in
foot
ft
mile
m.
1
0.001
10-6
0.0394
0.0033
5.4x10-7
m
1,000
1
0.001
39.4
3.28
5.4x10-4
km
106
1,000
1
39360
3280
0.5392
in
25.4
0.025
2.5x10-5
1
0.083
1.4x10-5
ft
305
0.305
3.0x10-4
12
1
1.9x10-4
m.
1.6x106
1,609
1.609
63,360
5,280
1
square
metre
m2
hectare
square
foot
ft2
acre
ha
square
kilometre
km2
m2
1
10-4
10-6
10.76
2.5x10-4
3.9x10-7
ha
10000
1
0.01
1.1x105
2.471
3.9x10-3
106
100
1
1.1x107
247.1
0.386
ft2
0.0929
9.3x10-6
9.3x10-8
1
2.3x10-5
3.6x10-8
acre
4,047
0.4047
4x10-3
43,560
1
1.6x10-3
sq.m.
2.6x106
259
2.590
2.8x107
640
1
mm
area
unit
abbreviation
km2
square mile
sq.m.
acre
17
volume
unit
abbreviation
L
cubic
metre
m3
L
1
10-3
1,000
1
m
3
litre
cubic inch
-5
gallon
(Imperial)
gal
cubic foot
in3
gallon
(US)
gal
61.02
0.264
0.220
0.0353
6,102
264
220
35.31
-3
-3
ft3
in3
0.0164
1.6x10
1
4.3x10
3.6x10
5.8x10-4
gal
3.785
3.8x10-3
231.1
1
0.833
0.134
gal
4.546
4.5x10-3
277.4
1.201
1
0.160
ft3
28.32
0.0283
1,728
7.47
6.23
1
mass
unit
abbreviation
gram
g
kilogram
kg
tonne
t
pound
lb
ton
ton
g
1
0.001
10-6
2.2x10-3
9.8x10-7
kg
1000
1
.001
2.205
9.8x10-4
t
106
1,000
1
2,205
0.984
lb
453.6
0.4536
4.5x10-4
1
4.5x10-4
106
1,016
1.016
2,240
1
ton
velocity
unit
metres/second kilometres/hour feet/second miles per hour
abbreviation
m/s
km/h
ft/s
mph
knots
kt
1
3.60
3.28
2.237
1.768
km/h
0.278
1
0.912
0.621
0.539
ft/s
0.305
1.097
1
0.682
0.592
mph
0.447
1.609
1.467
1
0.868
kt
0.566
1.853
1.689
1.152
1
m/s
18
rotation
unit
abbreviation
herz
Hz
revolutions per minute
rpm
radians/second
rad/s
1
60
6.283
rpm
0.0167
1
0.1047
rad/s
0.159
9.549
1
Hz
flow rate
unit
litre/minute
L/min
cubic
metres/second
m3/s
Imperial
gallons/minute
gal(Imp)/min
cubic
feet/second
ft3/s (or cusec)
L/min
1
1.7x10-5
0.220
5.9x10-4
m3/s
60,000
1
13,206
35.315
gal(Imp)/min
4.546
7.6x10-5
1
2.7x103
ft3/s
1,699
0.0283
373.7
1
abbreviation
force
unit
newton
kilonewton
tonne
kN
kilogram
force
kgf
ton
t
pound
force
lbf
abbreviation
N
N
1
0.001
0.102
1x10-4
0.225
1x10-4
kN
1,000
1
102
0.102
225
0.100
kgf
9.807
0.010
1
0.001
2.205
9.8x10-4
t
9,807
9.807
1,000
1
2,205
0.984
lbf
4.448
0.004
0.5436
4.5x10-4
1
4.5x10-4
ton
9,964
9.964
1,016
1.1016
2,240
1
ton
19
torque
unit
abbreviation
newton - metre
Nm
kilonewton - metre
kNm
pound - feet
lbf.ft
Nm
1
0.001
0.738
kNm
1,000
1
738
-3
1.365
lbf.ft
1.4x10
1
work/heat/energy (smaller units)
unit
calorie
joule
watt-hour
cal
J
Wh
1
4.182
1.2x10-3
3.9x10-3
3.088
1.6x10-6
J
0.239
1
2.8x10-4
9.4x10-4
0.7376
3.7x10-7
Wh
860.4
3,600
1
3.414
2,655
1.3x10-3
BTU
252
1,055
2.93
1
778
3.9x10-4
ft.lbf
0.324
1.356
3.8x10-4
1.3x10-3
1
5.0x10-7
hp.h
6.4x105
2.6x106
745.7
2,546
2.0x106
1
abbreviation
cal
British
foot-pound horsepowerThermal Unit
force
hour
BTU
ft.lbf
hp.h
work/heat/energy (larger units)
unit
abbreviation
kilocalorie megajoule
kcal
kilowatt
hour
MJ
kWh
-3
-3
British
Thermal
Unit
BTU
horsepo- Metric ton Metric ton
wer hour
of oil
of coal
hp.h
equivalent equivalent
mtoe*
mtce*
-3
-9
144.3x10
-6
31.42x10
-6
122.8x10
-9
37.53x10
64.13x10
-6
91.61x10
15,593
1
1.428
10,916
0.7001
1
kcal
1
4.2x10
1.2x10
3.968
1.6x10
100.3x10
MJ
239
1
0.2887
947.8
0.3725
23.88x10
kWh
860.4
3.6
1
3,414
1.341
85.98x10
BTU
0.252
1.1x10
2.9x10
1
3.9x10
26.27x10
hp.h
641.6
2.685
0.7457
2,546
1
41,868
11,630
38.062x10
6
6
mtoe*
mtce*
-3
6
9.969x10
6
6.979x10
29,310
-4
8,142
-4
26.645x10
-9
-6
-6
-9
-6
* These conversion ratios are based on the European Community norms of 1 tce = 29.31 GJ and 1 toe =
41.868 GJ. The United Nations uses slightly different conversion ratios. In practice, the calorific values
of both oil and coal may vary significantly.
20
power
unit
watt
kilowatt
abbreviation W (or J/s)
kW
metric
foot-pound/ horsepower British Thermal
horsepower second
Units/minute
CV
ft.lbf/s
hp
BTU/min
W
1
0.001
1.4x10-3
0.7376
1.3x10-3
0.0569
kW
1,000
1
1.360
737.6
1.341
56.9
CV
735
0.735
1
558
1.014
41.8
1.356
1.4x10-3
1.8x10-3
1
1.8x10-3
0.077
746
0.746
0.9860
550
1
42.44
17.57
0.0176
0.0239
12.96
0.0236
1
ft.lbf/s
hp
BTU/min
power flux
unit
abbreviation
watt/square metre
W/m2
kilowatt/square metre
kW/m2
horsepower/square foot
hp/ft2
W/m2
1
0.001
1.2x10-4
kW/m2
1,000
1
0.1246
hp/ft2
8,023
8.023
1
calorific value (heat of combustion)
calorie/gram
cal/g
megajoule/kilogram
MJ/kg
British Thermal Unit/pound
BTU/lb
cal/g
1
4.2x10-3
1.8
MJ/kg
239
1
430
BTU/lb
0.556
2.3x10
unit
abbreviation
-3
1
21
density (specific mass) and (net) calorific value (Heat of combustion) of some fuels
density (kg/m3)
calorific value (MJ/kg)
LPG
560
45.3
gasoline (petrol)
720
44.0
kerosene
806
43.1
diesel oil
850
42.7
fuel oil
961
40.1
varies
18-19
wood, oven dried
natural gas (1013 mbar, 0?C)
39.36 MJ/m3
NB These values are approximate, since the fuels vary in composition which affects both the
density and calorific value.
power equivalents*
Mtoe/yr
Mbd
Mtce/yr
GWth
PJ/yr
Mtoe/yr
1
0.02
1.55
1.43
45
Mbd
50
1
77
71
2,235
Mtce/yr
0.65
0.013
1
0.92
29
GWth
0.70
0.014
1.09
1
32
PJ/yr
0.02
4.5x10-4
0.034
0.031
1
* based on EC conversion factors
Mtoe/yr = Million tonnes of oil per year
Mbd = Million barrels of oil per day
Mtce/yr = Million tonnes of coal equivalent per year
GWth = Gigawatts thermal
PJ/yr = Petajoules per year
22
3. ENERGY ACCOUNTING
3.1 Equivalence and Replacement Values
When compiling energy statistics, or when comparing different fuel options for possible
substitution of one energy source for another, energy planners need a common unit of
measure. Primary energy can be physically quantified in a number of ways, depending on the
energy type of the resource. For example:
• mass (tonnes of solid fuel such as coal or biomass)
• volume (barrels for liquids, such as oil, or cubic metres for gases, such as biogas)
• rate of work (horsepower)
• velocity (metres per second for wind)
Biomass can be difficult to quantify, since it is measured in a variety of non-standard units, such
as head loads, buckets and bundles. A value in SI units has to be assigned to these nonstandard units, which can lead to considerable uncertainty in the data.
For national energy statistics, fuels are usually classified either by their heat content (joules) or
in fuel equivalence values (usually coal or oil equivalents). For the latter, an estimate is made
of what quantity of coal (in tonnes) or oil (in tonnes or barrels) has the same energy content.
Table 3.1 below gives equivalence values for some of the most common fuels.
Table 3.1 Energy equivalence values of major fuels
fuel
unita
tonnes of coal
equivalent b
(tce)
tonnes of oil
equivalentb
(toe)
barrels of oil
equivalentc
(boe)
GJa
coal
firewoodd (air dried)
tonne
tonne
1.00
0.46
0.70
0.32
5.05
2.34
29.3
13.6
kerosene
tonne
1.47
1.03
7.43
43.1
natural gas
gasoline (petrol)
gas oil/diesel
a
b
c
d
1,000 m
3
1.19
0.83
6.00
34.8
c
0.18
0.12
0.90
5.2
c
0.20
0.14
1.00
5.7
barrel
barrel
GJ/tonne is numerically equivalent to MJ/kg
The energy content of 1 tce and 1 toe varies. The values used here are the European Community
9
9
norms: 1 tce = 29.31 x 10 J and 1 toe = 41.868 x 10 J
3
1 barrel of oil = 42 US gallons = 0.158987 m
The energy equivalent of wood can vary by a factor of 3, depending on the moisture content of wood
and, to a lesser degree, species and ash content.
It is important to realise that equivalence values are not exact coefficients or conversion factors,
since they can only express a mean value of the heat content of one fuel compared with the
mean heat content of the same quantity of another reference energy source. It is a difficulty for
energy planners that most fuels have varying heating values. This is because fuels are not
23
homogeneous substances but are compounds, the make-up of which varies from one sample
of the fuel to another. To complicate matters further, there are other parameters which
influence the energy content, such as density and moisture content. This means that different
reference sources use different values for their units of measure (footnote b in Table 3.1
indicates that the values given in the table are European Community norms, and this must be
taken into account when comparing them with other equivalence values).
Another complication is that the energy required to achieve a certain output depends upon the
efficiency of the conversion device used. This means that when considering substituting one
energy form for another, more or less input energy maybe needed to serve the same end use,
depending on what equipment is used to convert each energy form. In this case, energy
equivalence values have a limited use for energy planners, since they are more interested in
the quantities of the different forms of energy used. How much is needed to replace one source
of energy by another becomes the unit of measure here. Coal or oil are usually used as the
reference value for the replacement value of an energy form, again expressed in terms of
tonnes of coal equivalent (tce) or tonnes/barrels of oil equivalent (toe or boe).
Table 3.2 gives examples of coal replacement values for some fuels. The end use has to be
specified in order to reflect the different conversion efficiencies. (See for example the kerosene
values for lamp and stove). The figures vary on a case-to-case basis.
Table 3.2 Coal replacement values of some energy forms
Fuel
Unit
Soft coke
Kerosene (Pressure stove)
Kerosene (Wick-fed stove)
Kerosene (Lamps)
Electricity
L.Diesel.
H.S.Diesel
Charcoal
Firewood (Closed chullah)
Firewood (Open chullah)
Dung-cake
Vegetable wastes
kg
Litre
Litre
Litre
kWh
Litre
Litre
kg
kg
kg
kg
kg
Coal replacement per unit
(kg CR)
1.50
6.98
5.20
2.10
0.70
7.68
7.44
1.81
0.95
0.70
0.30
0.61
3.2 Energy Balances
An energy balance is a set of relationships accounting for all the energy which is produced and
consumed, and matches inputs and outputs, in a system over a given time period. The system
can be anything from a whole country to an area to a process in a factory. An energy balance is
usually made with reference to a year, though it can also be made for consecutive years to show
variations over time.
24
Energy balances provide overviews, and are basic energy planning tools for analysing the current
and projected energy situation. The overviews aid sustainable resource management, indicating
options for energy saving, or for policies of energy pricing and redistribution, etc. There are a
number of different types of energy balance which can be made, depending on the information
you need: the energy commodity account, the energy balance and the economic balance.
the energy commodity account
The energy commodity account includes all flows of energy carriers, from the point of extraction
through conversion to end-use, in terms of their original, physical units such as kilotons of coal
and GWh of electricity.
the energy balance
The energy balance is similar to the energy commodity account, except for the fact that all
physical units are converted into a single energy unit (e.g. TJ, ktoe, ktce etc.). This type of
balance uses mean energy content values because of the inevitable variations in fuel composition,
especially with coal. This means that there are inherent inaccuracies within the balance, but as
long as they are within accepted limits, this is common practice. The conversion ratios used
always need to be noted with the balance.
the economic balance
In the economic balance, different forms of energy are accounted for in terms of their monetary
value. However, variations in currency rate, subsidies, taxes etc. make it difficult to compare
different energy forms, especially between countries.
An important part of preparing an energy balance is the construction of an energy chain to trace
the flows of energy within an economy or system, starting from the primary source(s) of supply
through the processes of conversion, transformation and transportation, to final/delivered energy
and finishing with end use. The data can be laid out either in table form or in a flow diagram (see,
for example, Figure 1.2).
All too frequently, energy balances are constructed in terms of primary energy without taking
into account conversions or transformations. This can lead to incorrect conclusions. The most
common example is electricity, a secondary energy form. Electricity is usually included in a
primary energy balance either on the basis of the amount of fossil fuel needed to produce it, or,
when the electricity is generated from hydro, nuclear or renewables, an energy equivalent or
heat content is used. However, it is not simply a matter of taking a conversion of one single fuel
to another, since the conversion efficiency varies with the primary energy source. For example,
for hydro it is around 90% whereas for coal it is around 40%. The amount of energy required to
produce the electricity needs to reflect these differences. To produce one unit of electricity
would take at least twice the amount of energy (on a joule basis) using coal as using hydro.
An energy balance should include the following:
• commercial energy. It should be clearly specified which energy forms are included in
commercial and in non-commercial energy categories (see the discussion in Section 1.7).;
25
• non-commercial energy, which usually includes biomass (woody and agricultural residues)
and animate energy. Despite their important contribution to the energy supply, particularly in
rural areas, these sources do not usually appear in national energy balances. They are
difficult to quantify physically since they are traded and used in non-standard units and also
they fall outside of the monetised economy, so their flows are not monitored. A few countries
now include agricultural processing residues, such as bagasse and rice husk, in their energy
balances.;
• non-energy products from primary energy carriers such as petrochemicals from crude oil,
coal and natural gas, should be listed as a separate column.
• energy imports, exports, bunkers, stock changes, transformation (conversion of one fuel to
another, for example coal to coke), distribution and conversion losses as well as, if relevant,
self consumption by the energy industry, should all be included;
• an energy balance is usually constructed from two sides: 1) from end-uses back to total
primary energy consumption, and 2) from resource extraction to primary energy supply. A
statistical difference is sometimes included to balance for inaccuracies in supply and
demand, for example, due to evaluation of losses. (These statistical differences can
sometimes be as high as 10%.)
A number of inconsistencies can arise between energy balances from different countries:
• energy consumption for the extraction and preparation of primary energy sources (like coal
mining) can be listed under energy consumption of the energy sector, or under losses, or the
primary source may be valued as the extracted and prepared stock;
• apparent energy losses can be technical or physical (transmission and distribution) losses
but can also be unmetered losses;
• some energy sources have multiple uses, such as wood (e.g. construction) or oil (e.g.
lubrication), but the total amount, including non-energy uses, is often included.
The basic equation of an energy balance is:
source + import = export + variation of stock + use + loss + statistical differences
In this equation,
⇒ sources are local primary energy sources;
⇒ imports are energy sources which come from outside the country (or -depending on the
boundary of the system under consideration- region, village etc.);
⇒ exports go to other countries, (regions, areas etc.);
⇒ variations of stock are reductions of stock (wood, oil) and storage;
⇒ use can be specified sectorally or by energy form or by end use. This includes use of fuels
for non-energy purposes;
⇒ losses can be technical and administrative.
⇒ statistical differences arise since an energy balance is constructed from both resource- and
end-use side with unavoidable inaccuracies.
26
A national energy balance is usually displayed as a matrix. The columns represent the various
fuels and the rows represent the energy uses of the different activities. The cells of the matrix
represent how much energy is added or subtracted by the activity of the row to the fuel in that
specific column. Not all cells contain data.
Table 3.3 An example of a national energy balance matrix
Supply and
consumption
Coal
Other
solid
fuel
Crude Petroleum
oil
products
Gas
Hydro Biomass Nonenergy
use
national production
+ imports
- stock changes
- exports
total primary supply
- energy
transformations
- sectors own uses
- losses
final energy production
total final consumption
industry sector
transport
agriculture
commercial
residential
energy industry
Table 3.3 shows an example of a blank energy balance sheet. The upper part of the matrix
represents the production side and the lower part the consumption side. Brackets indicate
negative figures. It could be broken down further, for example under industry different subsectors could be included (iron and steel, chemical, ferrous, paper, construction etc.) and
transport could be defined in terms of form (road, rail, air or water).
3.3 Energy Auditing
Energy accounting is an energy balance prepared at the micro-level usually for a firm using
different energy forms. It is the basis of energy conservation with the aim of a more rational use
of energy. An energy audit is the basic tool of energy accounting and is a systematic method
of identifying and accounting for energy flows through an industrial system or process.
An energy audit uses energy units rather than economic units. The starting point is an analysis
based on the First Law of Thermodynamics, which looks at the energy input and output at each
stage of a process.
Some energy audits also include an energy analysis based on the Second Law of
Thermodynamics, which allows for the calculation of the minimum theoretical energy necessary
for manufacturing a particular product. This value can then be used as a reference for
27
comparison with actual energy use by an industry so enabling energy efficient targets to be set
for reducing energy consumption.
The process energy requirement (PER) of a product is the direct energy input into the
production process and related transport requirements. This value is of interest to the
management of a factory. However, an energy planner may wish to take a much broader view
and consider the energy content of the input materials (for example, in an agricultural
processing factory, such as rice milling, the energy used in producing the fertilisers used to
grow the rice). This form of analysis can be taken further to include the energy required by the
machines to produce these materials, and even further to include the energy required by the
machine tools to make the machines. This more extended analysis is known as the gross
energy requirement (GER). The PER and GER figures themselves do not give information
about types of energy used or variations in energy flows.
28
4. GENERAL ENERGY DATA
4.1 World Energy Production and Consumption
World Energy Consumption 1990 per Sub Region
including alternative and traditional sources of energy
TECa
Consumption of different sources of energy
Coal
Oil
Natural
Gas
Fos.b
Alt.c
EJ
% of TEC
World
363
25
36
20
81
13
North America
Western Europe
J.A.NZg
95.8
61.0
23.1
22
22
21
38
43
51
24
16
12
83
80
84
East
Eastern Europe
ex-USSR
73.1
14.7
58.3
25
46
20
29
25
31
36
19
40
Africa
North and South Africa
sub-Sahara
15.1
6.45
8.63
21
na
na
27
na
na
Asia
China
India
Other
61.82
30.1
10.6
21.1
49
72
41
19
Latin America
Brazil
Mexico
Other
23.3
7.75
5.95
9.55
Middle East
9.76
Con/Cape Con/GNPf
Trad.d
GJ/cap
MJ/$
6
68.7
17.6
15
19
16
2
1
1
348
142
160
16.7
10.5
7.12
91
90
91
8
9
8
1
1
1
177
118
202
23.9
38.1
21.8
9
na
na
57
92
30
6
3
9
37
5
61
23.4
42.7
17.6
38.9
28.5
54.4
25
15
23
39
4
2
4
8
78
89
68
66
7
5
7
11
15
6
25
23
22.2
26.4
12.6
26.0
49.8
76.6
36.8
37.7
4
5
5
4
45
34
49
51
14
2
22
20
63
41
75
74
22
29
20
17
15
30
5
9
51.9
51.5
67.0
45.6
27.6
20.5
34.8
32.2
1
64
32
98
1
1
75.8
26.4
a
Total Energy Consumption; b Sum of fossil fuels (coal, oil, natural gas); c Alternatives (nuclear, hydro, wind,
geothermal, etc.); d Traditional (woodfuel); e Consumption of energy per capita; f Consumption per dollar of Gross
National Product produced; g J.A.NZ: Japan, Australia, New Zealand
Source: Energy Policy, Vol 22 (1), 1994
World Commercial Energy Production and Consumption in 1994 per sub region and
major producing and consuming countries
(million tonnes of oil equivalent)
TECa
Production of different
sources of energy
Oilb
Natural
Gas
Coalc
Consumption of different
sources of energy
Oilb
Natural
Gas
3172.4
1824.2
Coalc
2153.2
Nuclear
Energy
573.1
HydroElectric.
201.0
TOTAL WORLD
7923.8
North America
USA
Canada
Mexico
2358.4
2028.6
222.5
107.3
652.5
386.3
106.2
160.0
632.5
487.9
121.7
22.9
593.1
550.1
39.5
3.5
964.0
807.9
79.5
76.6
620.0
533.2
63.5
23.3
521.4
492.5
24.9
4.0
202.5
173.6
27.8
1.1
50.5
21.4
26.8
2.3
South & Central America
Argentina
Bolivia
Brazil
Colombia
Ecuador
Peru
Trinidad
Venezuela
306.0
46.3
267.2
35.1
63.3
20.0
3.0
23.6
186.3
19.6
64.7
21.9
17.2
0.8
2.1
2.1
35.6
2.0
102.3
34.5
23.4
18.5
6.5
6.5
138.0
2.5
17
66.7
4.2
10.1
<0.05
21.2
3.9
23.3
1.3f
19.6
24.9
0.3
-
4.5
Western Europe
Austria
Belgium & Luxembourg
Denmark
Finland
France
Germany
Greece
Iceland
Republic of Ireland
Italy
Netherlands
Norway
Portugal
Spain
Sweden
Switzerland
Turkey
United Kingdom
1429.3
22.9
55.2
20.6
22.9
232.0
333.2
25.7
1.2
9.4
150.1
80.2
20.3
15.7
94.5
43.7
23.8
56.6
217.8
286.7
188.8
153.2
0.5
2.9
14.0
5.5
76.5
7.9
18.1
59.3
27.6
0.1
126.7
58.9
652.5
11.3
26.8
10.1
10.4
90.5
135.1
17.2
0.7
5.2
92.3
36.3
9.8
11.6
53.5
16.6
12.7
25.8
83.1
263.2
5.8
10.1
2.5
2.7
27.7
61.1
<0.05
2.2
40.9
34.2
6.5
0.7
2.0
5.9
60.9
261.8
2.5
8.4
8.0
4.1
14.1
96.3
8.2
0.1
2.0
12.8
8.8
0.8
3.4
17.7
2.1
0.2
21.9
50.2
209.3
9.9
4.7
92.8
39.0
0.9
14.4
19.0
5.7
22.9
42.4
3.3
<0.05
<0.05
1.0
6.9
1.6
0.2
0.4
0.1
4.1
9.8
0.7
2.4
5.1
3.2
3.0
0.6
Eastern Europe
Former Soviet Union:
- Russian Fed.
- Ukraine
- Kazakhstan
- Azerbaijan
- Uzbekistan
- Turkmenistan
Bulgaria
Czech Rep & Slovakia
Hungary
Poland
Romania
1270.3
1001.3
664.6
158.0
375.5
361.8
316.0
628.5
603.8
509.6
15.3
290.9
231.8
162.7
19.8
544.5
493.5
335.0
73.2
349.6
210.3
126.5
46.1
60.6
45.0
25.3
17.8
24.9
20.8
15.2
1.1
10.5
7.9
14.7
10.2
8.0
8.2
29.9
4.0
71.6
6.6
3.6
-
0.4
<0.05
0.2
49.3
9.1
129.3
14.1
20.3
9.6
19.1
29.2
370.8
224.7
120.8
48.6
53.7
39.6
29.9
57.6
23.6
94.6
0.50
6.9
15.1
4.9
29.2
3.7
86.4
7.5
World Commercial Energy Production and Consumption in 1994 per subregion and
major producing and consuming countries
(million tonnes of oil equivalent)
(cont)
TECa
Middle East
Abu Dhabi
Dubai & N. Emirates
Iran
Iraq
Kuwait
Oman
Qatar
Saudi Arabia
Syria
Yemen
297.0
Africa
South Africa
Algeria
Angola
Cameroon
Congo
Egypt
Gabon
Libya
Nigeria
226.4
95.2
Asia & Australia
Australia
Brunei
China
India
Indonesia
Japan
Malaysia
New Zealand
Pakistan
Papua New Guinea
Philippines
Singapore
South Korea
Taiwan
Thailand
Vietnam
2036.4
90.4
748.7
212.4
68.9
478.5
29.9
13.3
Production of different
sources of energy
Oilb
Natural
Gas
956.8
94.1
19.5
178.0
24.5
103.7
40.5
20.8
427.5
29.9
16.0
114.6
13.3
329.6
66.4
55.7
26.1
6.4
10.6
46.5
16.8
67.6
93.1
45.3
26.9
8.5
144.9
33.6
74.2
25.3
8.4
14.9
15.6
55.8
30.9
23.4
Coalc
Consumption of different
sources of energy
Oilb
Natural
Gas
Coalc
Nuclear
Energy
HydroElectric.
1.1
179.8
110.7
5.1
-
1.3
108.5
103.5
99.7
18.8
36.8
-
80.5
73.5
2.6
2.6
6.8
0.2
118.3
799.2
34.1
184.3
17.0
917.6
37.9
96.0
-
39.5
1.4
144.1
67.6
39.9
268.7
15.5
5.8
14.9
15.7
24.2
54.3
12.2
4.0
572.0
121.8
4.0
82.0
1.8
1.3
3.1
1.3
67.3
-
14.5
6.0
0.8
6.3
0.4
2.2
15.1
23.7
85.1
32.4
29.3
1.4
7.6
3.6
9.1
1.5
26.5
16.2
46.4
15.1
9.0
-
0.5
0.4
0.8
0.4
27.9
11.6
33.9
9.5
5.6
3.7
12.5
592.0
122.9
18.8
2.2
1.5
5.7
17.0
25.0
134.8
61.9
45.0
6.9
a
Total Energy Consumption; b includes: crude oil, oil sands, and natural gas liquids (the liquid content of natural gas where this is
recovered separately), excludes: liquid fuels from other sources, such as coal derivatives; c commercial solid fuels only, i.e. bituminous coal
and anthracite (hard coal), and lignite and brown (sub-bituminous) coal
Source: BP Statistical Review of World Energy, June 1995
Figure 4.1. Growth in commercial energy consumption (1985-1988)
16
14
M alaysia
Thailand
12
10
% grow th
p.a.
S.Korea
8
India
6
Brazil
A f rica
Indonesia
4
USSR
China
Asia
USA
2
Japan
Net h erlands
W .Germ a n y
0.5
0
-2 0
Europe
1
1.5
2
2.5
-4
Consumption (billion toe)
Figure 4.2. Growth in commercial energy consumption (1989-1992)
16
M alaysia
14
W orld Totals
Usage 7 . 6 E+ 9 toe
Grow th 0 . 4 % pa
Thailand
12
S.Korea
10
Indonesia
8
A sia
% grow th
6
p.a.
India
4
Japan
Oceania
China
S.A m erica
2
Brazil
0
Netherlands
Africa
0
-2
USA
0.5
1
1.5
USSR
-4
Consumption (billion toe)
32
2
Europe
W .Germany
N . A m erica
2.5
Table 4.3. Increase in energy use expected as a result of population increases
Year
Population
(billions)
Total energy use
(EJ/y)
(TW*)
Energy use per person
(GJ/Y)
(kW*)
1990 (dev)
1990 (ldc)
1990 (world)
1.2
4.1
5.3
284
142
426
9.0
4.5
13.5
237
35
80
7.5
1.1
2.5
2025 (dev)
2025 (ldc)
2025 (world)
1.4
6.8
8.2
167
473
640
5.3
15.0
20.3
120
69
78
3.8
2.2
2.5
* = equivalent continuous power
dev = developed countries
ldc = less developed countries
4.2 Biomass Energy Consumption in RWEDP Member Countries
Table 4.4. RWEDP-specific data on biomass fuel use
Biomass Energy
Consumption (PJ)
1981
Bangladesh
Bhutan
Cambodia
China
India
Indonesia
Lao PDR
Malaysia
Myanmar
Nepal
Pakistan
Philippines
Sri Lanka
Thailand
Vietnam
Total
243
7
41
1,541
2,165
1,181
29
69
156
113
192
308
70
484
197
6,755
1986
262
9
47
1,820
2,441
1,320
33
78
175
197
233
327
78
546
222
7,742
1991
277
12
54
2,018
2,824
1,465
39
90
193
206
296
382
89
526
251
8,666
Av. annual growth in
biomass en. cons. (%/y)
1981-86
1986-91
1.6
4.7
2.9
3.4
2.4
2.3
2.5
2.4
2.3
11.7
4.0
1.2
2.1
2.5
2.4
2.8
1.1
4.9
2.5
2.1
3.0
2.1
3.0
2.9
1.9
0.9
4.9
3.1
2.8
-0.7
2.4
2.3
Av. ann. growth during
1981-1991 (%/y)
population
2.5
2.2
3.3
1.5
2.1
2.0
2.9
2.7
2.2
2.8
3.3
2.5
1.5
1.5
2.2
1.9
GDP
4.1
6.5
5.3*
9.1
5.2
5.5
NA
6.2
1.1
4.5
6.0
1.2
4.1
8.0
NA
7.0
* for the period 1987-1993
Source: WRI, 1995
33
Table 4.5. Contribution of biomass in total energy supply
Country
Year
Share of
Share of
Share of Biomass in Source
Biomass (%) Woodfuel (%) Domestic Sector (%)
Bangladesh
1992
Bhutan
1993
Cambodia
1995
China
1994
India
1992
Indonesia
1994
Laos
1993
Malaysia
1992
Maldives
1994
Myanmar
1992-93
Nepal
1994-95
Pakistan
1993-94
Philippines
1994
Sri Lanka
1992
Thailand
1995
Vietnam
1993
1 - no data available
3 National energy balance
5 United Nations
73
86
85
23
33
36
89
7
23
86
92
47
39
72
24
44
89
UN
WRI
82
98
MIME
65
IEA
78
UN
73
IEA
WRI
21
AEEMTRC
23
84
UN
86
99
DOE
69
98
WECS
27
83
Energy Wing
84
IEA
69
91
CEB
17
62
DEDP
WRI
2 Domestic and commercial sector
4 World Resource Institute
6 AEEMTRC
.
Figure 4.3. Conventional vs. wood and biomass energy consumption in Nepal
300,000
100
90
250,000
80
70
200,000
60
50
40
% share
GJ 150,000
Conventional
Biomass
Wood
Share of Biomass
Share of W ood
100,000
30
20
50,000
10
-
0
1980/81
Source:
34
1982/83
1984/85
1986/87
1988/89
1990/91
1992/93
1994/95
Energy Sector Synopsis Report 1992/93 (2049/50), Water and Energy
Commission Secretariat, Ministry of Water Resources, 1994
5. FUELS AND COMBUSTION
Combustion occures when a fuel burns. This chemical reaction involves oxygen, and usually
takes place in air (although for some special applications it takes place in pure oxygen), during
which the chemical energy of the molecules is converted into heat energy. The main products
are carbon dioxide and water.
All fuels consist primarily of carbon, hydrogen and, in some cases, oxygen, but in different
proportions. (Although the term nuclear fuels is used, this is not strictly correct since the heat
produced by nuclear reactions is not obtained through a combustion process.) The energy
content of a fuel depends upon its chemical composition and a number of other parameters,
such as density and moisture content. Biomass fuels in particular are subject to a wide variation
in their energy content, not only because of the differences in chemical composition but also
due to the influence of a number of parameters such as:
• moisture content,
• ash content, and
• bulk density.
5.1 Chemical Composition
All biomass consists of an organic fraction, an inorganic fraction and water. It is the organic
fraction which burns, although the inorganic component does influence the combustion process
and forms ash, the solid residue remaining after combustion. Ash is discussed below. Table 5.1
gives the typical elemental composition of some different species of woody biomass and
agricultural residues.
Table 5.1 Elemental (or ultimate) analysis of selected biomass fuels
(weight %, oven dry basis)
Biomass
Black oak1
Douglas fir1
Red alder1
Cotton gin trash1
Rice hulls1
Rice straw2
Sugar cane bagasse2
Coconut shell and fibre2
Wheat straw2
Maize straw2
Elemental per cent
Carbon Hydrogen Oxygen Nitrogen
49.0
6.0
43.5
0.15
50.6
6.2
43.0
0.06
49.6
6.1
43.8
0.13
42.8
5.1
35.4
1.53
38.3
4.4
35.5
0.83
41.44
5.04
39.94
0.67
46.95
6.10
42.65
0.30
51.50
5.70
41.00
0.35
48.53
5.53
39.08
0.28
47.09
5.54
39.79
0.81
Sulphur
0.02
0.02
0.07
0.55
0.06
0.13
0.10
0.10
0.05
0.12
Ash
1.34
0.10
0.41
14.7
21.0
17.4
3.90
1.80
6.53
5.77
1
Source: Strehler and Stutzle, Biomass Residues, in Biomass, Hall and Overend (eds), 1987
Source: Rossi (1984) quoted by Tillman, Biomass Combustion, in Biomass, Hall and Overend
(eds), 1987
2
35
5.2 Moisture Content
The moisture content of biomass is defined as the quantity of water in the material, expressed
as a percentage of the material’s weight. Moisture content is the most critical factor governing
the amount of useful heat from biomass combustion. The water has to be evaporated first
before heat is available for its end application. Put simply, the higher the moisture content the
lower the useful energy available. The heat losses related to water in a biomass fuel are due to:
1. warming up the water stored in the plant tissues to the evaporation point;
2. evaporating this water; and
3. removal by water formed as vapour during combustion reactions.
The heat loss in (3.) is present when all fuels combust, and major design efforts are made to
utilise this energy through the use of heat exchangers. Although all fuels contain trace amounts
of water (attempts are made during processing, transport and storage to ensure this is kept to a
minimum), it is in biomass that the levels are most significant. The moisture content varies
between types of biomass, the length of time between cutting and using and the atmospheric
humidity. When the biomass is cut it will lose moisture until it reaches equilibrium with its
environment (a piece of wood from the same species would have a different moisture content in
the monsoon climatic region than if it were in the Sahara desert). Therefore, when trying to
compare the fuel characteristics of different types of biomass, it is important to state the
moisture content.
Assigning a moisture content value can be confusing since there are three ways in which
moisture content can be defined. The quantity of water can be a percentage of the biomass
weight on:
• a wet basis;
• a dry basis; and
• a dry and ash free basis.
The consequence of this is that the same piece of biomass could be given three different
values for moisture content! Therefore, not only should the heat content of a particular biomass
type state at what moisture content the value is given, but the basis on which a moisture
content itself is defined should also always be quoted.
When biomass is first cut it always contains some moisture. The mass of the material can be
analysed in terms of three components: dry matter (W daf), ash (W ash) and water (W H2O). The
total mass of the wet material (W wm) is therefore given by:
W wm = W daf + Wash + WH2O
moisture content on wet basis (mcwb)
The mass of water is expressed as a percentage of the total mass of the biomass (water, ash,
and dry, combustible matter).
36
mcwb =
W H 2O
W daf + W ash + W H 2 o
=
W H 2O
W wm
(5.1)
moisture content on dry basis (mcdb)
The mass of water is expressed as a percentage of the mass of the dry matter plus the mass of
the ash.
mcdb =
W H 2O
W daf + W ash
=
W H 2O
Box 5.2 MOISTURE CONTENT ON
DRY BASIS (mcdb)
Using data from
equation 5.2:
mcdb =
0.15
0.8 + 0.05
Box
5.1
It is also possible to convert the values between the two
systems:
in
mcdb =
mcwb
× 100
100 − mcwb
mcwb =
mcdb
× 100
100 + mcdb
and
= 0.176 = 17.6%
Box 5.3 MOISTURE CONTENT ON
DRY ASH FREE BASIS (mcdaf)
Using data from Box 5.1 in
equation 5.3:
mcdaf =
(5.2)
W wm - W H 2O
0.15
= 0.188 = 18%
0.80
moisture content on dry, ash free basis (mcdaf)
The moisture content can also be related to the mass of the
dry combustible solid matter alone.
mcdaf =
WH2 O
Wdaf
=
WH2 O
Wwm − Wash − WH2 O
(5.3)
oven dried, air dried, green, wet biomass
Another source of confusion is that data on the energy Box 5.1 MOISTURE CONTENT ON
content of biomass is often referred to on the basis of WET BASIS (mcwb)
the biomass being oven dried, air dried, green or A 1 kg piece of wet biomass is
wet. Oven dried means that the biomass was heated in found to contain 0.8 kg of dry
an oven, under laboratory conditions, until a constant matter, 0.05 kg of ash and 0.15
weight was recorded, i.e. until all the moisture had kg of water. Therefore, from
been driven off. Green means the biomass was equation (5.1) the mcwb is given
weighed with the moisture content it had at the moment by:
of cutting. However, this is not an accurate value, since
0.15
mcwb =
= 0.15 = 15%
all biomass begins to lose some moisture as soon as it
1
is cut. Air dried means that the biomass was allowed to
dry so that it was in equilibrium with atmospheric humidity (see Figure 5.1.). As was mentioned
above, this is site specific. Wet biomass is sometimes used synonymously with green wood, but
it actually includes both green and air dried biomass. Of these values, only oven drying gives a
37
unique value. Therefore, any value assigned to the energy content of biomass should state at
which moisture content the measurement was made. There is considerable debate about which
value to use in calculations, since although oven dried gives the only consistent value it is not
the form in which it is used.
Figure 5.1. Effect of relative humidity on equilibrium moisture content of wood
(Household Energy Handbook, World Bank technical paper 67, 1987)
As a guide (since figures are highly dependent on local conditions), the moisture content of
wood on a dry basis is around:
• 0% for bone dry or oven dried wood
• 6% for kiln dried wood
• 7-15% for air dried
• 28-35% for wet wood (for some species it is higher).
5.3 Ash Content
The size of the inorganic component of biomass varies widely and is made up of a wide range
of elements. The ash content can be expressed in the same way as the moisture content on a
wet basis, dry basis or an ash free basis. In general, the ash content on a dry basis is the one
usually used.
38
ash content on a wet basis (acw)
acw =
Wdaf
Wash
W
= ash
+ Wash + WH2O Wwm
Box 5.4 CALCULATING ASH CONTENT
Inserting the data from Box 5.1 into equations
(5.4) 5.4, 5.5, and 5.6 gives the following:
ash content on a dry basis (acd)
acd =
Wash
Wash
=
Wdaf + Wash Wwm − WH2O
acw =
0.05
= 0.05 = 5.0%
1.0
acd =
0.05
= 0.059 = 5.9%
0.8 + 0.05
acd =
0.05
= 0.063 = 6.3%
0.8
(5.5)
ash content on a dry and ash free basis (acdaf)
acdaf =
Wash
Wash
=
Wdaf Wwm − Wash − WH 2 O
(5.6)
5.4 Heating Values
The energy released on combustion is indicated by the heating value of the fuel, which is the
energy per unit mass of the fuel (J/kg) for solids (known as specific energy) and, for liquids
and gases, the energy per unit of volume (MJ/L and MJ/m3 at 1 atmosphere, both measured at
15EC - known as the energy density). There is no single heating value for a specific fuel. The
two most commonly used measures are the Higher Heating Value (HHV) and the Lower
Heating Value (LHV). These values are related to the physical state of the water produced on
combustion. During combustion the water is produced initially as steam and therefore contains
a lot of energy. If the steam escapes without doing any useful work then this is a loss of energy
to the process. The energy available for completing the task in hand is therefore in practice less
than the maximum; this is the LHV.
Figure 5.2. Relationship between several heating value definitions (Household Energy
Handbook, World Bank technical paper 67, 1987)
Theoretically, one could fully condense and cool the steam to the original temperature before it
is allowed to escape, then all heat would be recovered, and the corresponding heating value
39
would be the Higher Heating Value (HHV). For calculations involving steam and gasifiers, the
values have to be adjusted to take into account that the combustion products are at constant
pressure, which is not reflected in the manner in which specific energy is measured in the
laboratory.
A piece of wood contains free and bound water that are both released during combustion. Free
water refers to the moisture content as described before, and can be removed when drying in
an oven. Bound water is water that forms during combustion as a chemical reaction from
hydrogen atoms in the cellulose and oxygen from outside.
Higher Heating Values on dry and ash free, dry and wet basis
As with moisture content, the HHV/LHV should, since the units are on a mass basis, be quoted
with reference to the state of the fuel, that is, wet, dry or dry and ash free. The HHVdaf of all
types of biomass is in the order of 20,400 kJ/kg ("15%). On an energy density basis biomass
fuels have approximately one-tenth of the value of fossil fuels, such as oil or high quality coal.
HHVd = HHVdaf ×
Wdaf
Box 5.5 CALCULATING HIGHER HEATING VALUES
Wdaf + Wash
Using the value obtained in Box 5.4, the higher
heating value on a dry basis can be obtained from
equation 5.7:

Wash 

= HHVdaf ×  1 −
 Wdaf + Wash 
= HHVdaf × (1 − acd )
HHVw = HHVdaf ×
= HHVdaf ×
= HHVdaf
HHVd = 20,400 × (1 − 0.059) = 19.196 kJ kg
(5.7)
Wdaf
Wdaf + Wash + WH2O
The higher heating value on a wet basis can be
obtained from equation 5.8 and the value calculated
in Box 5.1:
HHVW =
20,400 × (1 − 0.059) × (1 − 0.15) = 16,317 kJ kg
Wwm − Wash − WH 2 O
Wwm
× (1 − ac w − mcwb ) = HHVdaf × (1 − acd ) × (1 − mcwb )
BOX 5.6. USE OF 1M3 BIOGAS
1 m3 of biogas is enough for:
Cooking:
Lighting:
Driving:
Running:
Generating:
three meals for a family of 5 (China)
equal to a 60 watt bulb for 6 hours
a 3 tonne lorry for 2.8 km
a 1hp engine for 2 hours
1.2 kWh of electricity
NB Values are approximate due to variation in methane content of biogas
Source: after van Buren 1979.
From: Bioenergy and the environment - J. Pasztor and L. Kristoferson, 1990
40
(5.8)
Lower Heating Value on dry, ash free basis
The calculation of this value needs an ultimate analysis1 of the hydrogen content of the fuel,
represented as [ H ] daf :
Box 5.7 CALCULATING LOWER HEATING VALUES
Using the data calculated in Box 5.5 and taking the
LHVdaf = HHVdaf − H × 20,300
daf
hydrogen content in the fuel as 6% on a dry, ash
(5.9)
free basis, the lower heating values can be obtained
− mcdaf ×2,260
[ ]
from equations 5.9, 5.10 and 5.11 as follows:
Lower Heating Value on dry basis
LHVd = LHVdaf ×
= LHVdaf
= LHVdaf
LHVdaf
Wdaf
= 20,400 - 0.06×20,300 - 0.188 × 2,260
Wdaf + Wash


Wash
× 1 −

 Wdaf + Wash 
× (1 − acd )
= 18,757 kJ kg
LHVd = 18,757 × (1 − 0.059) = 17 ,650 kJ kg
(5.10)
= 15,030 kJ kg
Lower Heating Value on wet basis
LHVw = LHVdaf ×
Wdaf
Wdaf + Wash + WH2 O
LHVw = 18,757 × (1 - 0.059) × (1 - 0.15)
= LHVdaf ×
Wwm − Wash − WH2 O
Wwm
= LHVdaf × (1 − ac w − mcwb) = LHVdaf × (1 − ac d ) × (1 − mcwb)
(5.11)
5.5 Bulk Density
Density is defined as mass per unit volume. However, for biomass, due to the structure of the
material or the form in which it is to be utilised, there are three ways in which this density can be
expressed: true density, apparent density and bulk density. Biomass has a porous structure,
which means there are spaces between the cells, which contribute to the volume but not to the
mass.
True density is the mass per unit volume of solid matter of biomass. Apparent density is defined
as mass per unit volume enclosed within the boundary of the biomass particle, where the
volume includes the solid volume and the pore volume.
When biomass comes in small pieces, such as rice husk or sawdust, the density depends on
whether the pieces are piled loosely or have been compacted, since there are also spaces
between the particles (known as void volume). The density measured in this case is the bulk
density and obviously depends upon the degree of compaction. The volume includes the solid
volume, pore volume and void volume. For biomass the bulk density is either expressed on an
oven dry weight basis (mcod=0%) or an as received (wet) basis (mcwb), and should be at
standard packing conditions. Biomass densification reduces pore and void volume of the
particles.
1
Ultimate analysis of a fuel determines the carbon, oxygen, hydrogen, nitrogen, sulphur and ash content.
41
The three volumes are related as follows:
wa = ws (1 - εp)
wb = wa (1 - εb)
ws = true density, mass/volume
wa = apparent density, mass/volume
wb = bulk density, mass/volume
εp = particle porosity =
volume of pores
volume of pores and volume of solid
εb = bed porosity =
volume of external voids
volume of external voids and volume of particles
The bulk density of biomass show wide variations, from 150 to 200 kg/m3 for cereal straw to
around 600 to 800 kg/m3 for solid wood.
Table 5.2 Typical characteristics of biomass fuels used at present commercially for
energy generating purposes
Biomass type
Lower heating
value on wet basis
LHVw (kJ/kg)
7,700-8,000
Moisture content
on wet basis
MCw (%)
40-60
Ash content
on dry basis
Acd (%)
1.7-3.8
13,000-16,000
7-9
7-14
Coconut shells
18,000
8
4
Coffee husks
16,000
10
0.6
Cotton residues:
stalks
gin trash
16,000
14,000
10-20
9
0.1
12
13,000-15,000
10-20
2
3-7
5,000
11,000
15,000
15,000
63
40
15
15
5
9,000-15,000
13-15
1-20
Rice husks
14,000
9
19
Straw
12,000
10
4.4
Wood
8,400-17,000
10-60
0.25-1.7
Charcoal
25,000-32,000
1-10
0.5-6
Bagasse
Cocoa husks
Maize:
cobs
stalks
Palm oil residues:
fruit stems
fibres
shells
debris
Peat
42
5.6 Fuel Characteristics
Although all biomass fuels have similar Higher Heating Values (HHV), they show a large
variation with respect to physical (moisture content, bulk density), chemical (volatile matter
content, ash content) and morphological (size, size distribution) characteristics. These
characteristics influence the choice of conversion technology suitable for a particular fuel. For
example, wood and charcoal can be used with a wide range of conversion technologies with
little need of pre-processing, whereas many agricultural residues, for example, rice husk and
bagasse, require more dedicated equipment usually with pre-treatment to make handling and
transport easier, for example briquetting. Table 5.2 gives Lower Heating Value, moisture
content and ash content for some biomass fuels commonly used for commercial energy
generation.
Table 5.3. Energy content of various fuels
Fuel type
LHV on wet basis
Coal
27 GJ/tonne
Coke
28 GJ/tonne
Petrol
34 GJ/m3
Diesel fuel
36 GJ/m3
Heavy oil
Ethanol
Liquefied fuel gas
Natural gas
39 GJ/m3
26 GJ/tonne
46 GJ/tonne
0.03 GJ/m3
LNG (Liquefied Natural Gas)
20 GJ/m3
Peat (50% moisture content)
9 GJ/tonne
Peat (35% moisture content)
12 GJ/tonne
Wood (fresh)1
8 GJ/tonne
Wood (stored)1
14 GJ/tonne
Dung (15% moisture content)1
Biogas
Crop residues1
Pellets, briquettes1
12.6 GJ/tonne
3
22 MJ/m
14 - 18 GJ/tonne
18 GJ/tonne
1 All energy content values are approximate since they depend on chemical composition and moisture
content and significant variations for these fuels occur.
43
6. WOOD PRODUCTION FIGURES
Table 6.1. Energy and production characteristics for various tree and palm species
Scientific Name
Acacia auriculiformis
Acacia decurrens
Acacia farnesiana
Acacia leucopholea
Acacia mangium
Acacia mearnsii
Albizia falcataria
Albizia lebbeck
Albizia procera
Alnus nepalensis
Alstonia macrophylla
Anthocephalus cadamba
Antidesma ghaessimbilla
Avicennia officinalis
Bruguiera gymnorrhiza
Bruguiera parviflora
Bruguiera sexangula
Calliandra calothyrsus
Cassia fistula
Cassia siamea
Cassuarina equisetifolia
Ceriops tangal
Cocus nucifera
Cordia dichotoma
Dalbergia latifolia
Dalbergis sissoo
Derris indica
Diospyros philippinensis
Diospyros philosanthera
Eucalyptus camaldulensis
Eucalyptus deglupta
Eucalyptus globulus
Eucalyptus grandis
Eucalyptus urophylla
Gigantochloa apus
g
Gfiricidia sepium
Grevillea robusta
Gre wia multiflora
Inga vera
Lagerstroemia speciosa
44
Annual
Average
Yield
(m3/ha.yr)
10-20
17
19
30
10-25
30-40
5
10-20
15
5-10
6-10
5-10
e
10-20
10-15
5-15
15
10-15
f
17-35
10-30
17-60
19
15
8-20
15
10
Average
Possible
a
Rotation Regeneration
Length
(yrs)
8-12
S, C
8
S, C
S, C
20
S, C
S, C
7-10
S, C
5-15
S, C
10-15
S, C
S, C
15-20
S, C
S
9
S
S
30
S
30
S
30
S
1
S, C
S, C
5-10
S, C
7-10
S
S
S
S
20
S, C
S, C
4-5
S, C
S
S
f
7-10
S, C
S, C
5-15
S, C
6-10
S, C
9
S, C
5
S
8
S, C
10-15
S
S
3-5
S, C
15
S
Nitrogen
b
Fixing
Use
c
Priority
Oven-dry
density
3
Y
Y
Y
Y
Y
Y
Y
N
N
Y
N
N
Y
N
Y
Y
N
N
N
Y
Y
Y
Y
Y
Y
N
N
F
F
F
F
F
F
P, T, F
T, F
T, F
F, P
P, T
P, T
F
T, F
F
F
F, T
T, F
F, T
T, F
F
T, F
T
T
T
T, F
T
T
T, F
P, T, F
T, F
T, F
F, T
P, F
T, F
T
kg/m
600-800
840
650
700-850
330
550-600
660
320-370
560
330
600
630-700
700-1,000
700-1,000
810
510-780
520
600-800
800-1,200
810
660
680
750
580
430
430
800-1,000
400-550
740
570
450
570
590
d
HHV
(MJ/od kg)
17.7-20.3
18.7
19.2
21.8
16.7-19.3
18.1
21.8
19.7
16.0-18.3
19.2
18.9-19.8
19.1
18.5
20.4
18.7
19.4
18.9-19.9
18.4
18.8
19.0-21.1
19.6
19.0
18.4
19.8
19.0-21.0
19.3
18.6
18.1
19.0-21.0
18.7
20.1-21.0
19.0-20.5
18.4
19.0-20.6
19.3
Scientific Name
Leucaena diversifolia
Leucaena leucocephala
Prosopis pallida
Pterocarpus indica
Rhizophora apiculata
Rhizophora mucronata
Samanea samau
Schima noronhae
Schleichera oleosa
Sesbania grandiflora
Swietenia Macrophylla
Syzygium cumini
Tamarindus indica
Terminalia catappa
Trema orientalis
Xylocarpus granatum
Xylocarpus moluccensis
Zizyphus talanai
Annual
Average
Yield
(m3/ha.yr)
25
h
30-40
8
10
5-10
5-10
15
5-12
10
i
15-25
17
5
10-15
10
-
Average
Possible
a
Rotation Regeneration
Length
(yrs)
S, C
h
5-10
S, C
S
15
S, C
30
S
30
S
S, C
8
S
25
S
i
3-7
S, C
25
S, C
S, C
25
S, C
10-15
S
8
S, C
S
S
S
Nitrogen
b
Fixing
Use
c
Priority
Oven-dry
density
3
Y
Y
N
Y
Y
Y
Y
T, F
F, T
F
T, F
T, F
T, F
T, F
Y
N
N
Y
N
N
N
N
N
F
T
F
T, F
F
F
kg/m
540
530-580
800
700-1,000
700-1,000
520
420
770
590
250
560
580
690
d
HHV
(MJ/od kg)
17.5-19.5
19.0-20.5
20.1
21.3
20.0
18.7
19.3
20.7
20.1-20.5
16.3
15.4
18.3
Sources: Adapted from the University of Philippines (1981) and NAS (1980).
Notes:
Characteristics are presented for more than 60 trees or palms that have been or may be used as energy
sources. However, many species also have alternative or better uses, such as timber. The values in the table
above are not always comparable; since data come from a variety of studies, uniformity of measurements and
consistency of definitions cannot be assured. Some data are based on small species trials, making these date
only instructive, not definitive. Great care needs to be taken, especially with air-dry density and calorific value
estimates. Unfortunately, the moisture content for the air-dry weight was usually not given in most research.
Calorific values generally are assumed to be high heat values-oven-dry energy contents. Rounding errors and
varying measurement conditions, however, make the data on HHV suggestive at best. These problems may not
be too critical to rough estimates since energy contents do not vary widely among most species. An average
"wood" value often used is 15 MJ/kg at 15 percent mcwb, or 13 MJ/kg at 25 percent mcwb. The table does not
mean to suggest that every species be used as fuelwood; it merely gives particular characteristics.
a Regeneration code: C means tree can be coppiced; S means that regeneration is primarily from seeds or
plantings.
b Nitrogen-fixing code: Y means that the plant has the ability to fix nitrogen and thereby will enrich the soil; N
means that the plant does not fix nitrogen.
c Use priority provides a hierarchy of uses for the plant, with P indicating pulpwood, T timber, and F fuelwood.
The typical ranking of use priority is indicated by the order of the symbols, although priority may change among
different users.
d HHVs may vary by 10-20 percent.
e Average yields often increase to 30-65 m3/ha.yr after the first cutting at six months to a year.
f Values are given for good sites; poor, dry sites average 2-11 m3/ha on a 10-14 year rotation.
g Also known as Gliricidia maculata.
h Well-managed plantations of giant L. leucocephala report 50-100 m3/ha.yr on a 3-5 year rotation.
i Data for well-managed plantations.
45
7. ELECTRICITY PRODUCTION AND CONSUMPTION
Figure 7.1. Growth in electricity consumption (1985-1988)
18
W orld T o t a ls
U s a g e 1 1 E+ 1 2 k W h
G row t h 4 . 4 % pa
16
14
Thailand
S.Korea
12
India
10
China
M alaysia
% grow t h
p.a.
8
Indonesia
A f rica
6
A s ia
Brazil
Netherlands
4
USA
Europe
Japan
USSR
2
W .Germ a n y
0
0
1
2
3
4
-2
C o n s u m p t ion (1 0
12
k W h)
Figure 7.2. Growth in electricity consumption (1989-1992)
18
Thailand
M alaysia
16
W orld Totals
Usage 1 2 E+ 1 2 k W h
Grow th 1 . 6 % pa
S.Korea
14
12
10
China
A sia
% grow th
p.a.
8
India
6
Netherlands
S.A m erica
4
Brazil
A f rica
Oceania
Indonesia
2
Japan
USA
N . A m erica
Europe
0
0
0 . 5W .Germ any 1
1.5
USSR
2
2.5
-2
Consumption (x1 0
46
12
kWh)
3
3.5
4
Figure 7.3. Electricity consumption versus Gross Domestic Product (1991)
100,000
Sources
Electricity : Energy Statistics Yearbook 1992 (UN)
GDP: World Development Report 1993 (World Bank)
New Zealand
10,000
Norw ay
Canada
USA
Japan
Netherlands
Hungary
Elect ricit y
Consumption
kWh/Cap
Brazil
M exico
Thailand
1,000
Egypt
China
India
Ghana
Indonesia
100
Bangladesh
Nepal
Tanzania
10
10
100
1,000
GDP/Cap
10,000
100,000
($ /Cap)
Figure 7.4. Electricity as a part of total energy consumption in German industry
180
1990
160
1980
140
1970
120
Elect ricit y 1 0 0
Consum p t ion
( T W h)
80
1960
60
40
1950
20
0
0
100
200
300
400
500
600
700
T o t a l Energy Consum p t ion (T W h)
47
Table 7.1. Growth in electricity consumption in RWEDP countries
Country
Bangladesh
Bhutan
China PDR
India
Indonesia
Lao PDR
Malaysia
Maldives
Myanmar
Nepal
Pakistan
Philippines
Sri Lanka
Thailand
Vietnam
Total/average
Aggregate Consumption (GWh)
1980
1990 growth (%/y)
1,406
4,705
13%
259,212
541,174
8%
82,367
184,222
8%
6,560
27,741
16%
183
7,967
19,093
9%
2
22
27%
854
1,840
8%
162
524
12%
10,349
29,229
11%
12,637
20,087
5%
1,392
2,608
6%
12,730
36,896
11%
395,688
868,425
8%
Per Capita Consumption (kWh)
1980
1990 growth (%/y)
16
42
10%
264
479
6%
122
223
6%
44
156
13%
44
579
1,075
6%
11
103
25%
26
45
6%
11
28
10%
125
261
8%
263
331
2%
94
154
5%
272
655
9%
1,835
3,608
7%
Note: For Bhutan, Lao PDR and Vietnam, not all data is available.
Source: ADB (1993)
Table 7.2. Share of number of households with access to electricity (1990)
Country
Bangladesh
China PDR
India
Indonesia
Malaysia
Myanmar
Nepal
Pakistan
Philippines
Sri Lanka
Thailand
Vietnam
1
share of total number of
households1
12%
66%
80%3
24%
82%
6%
9%
37%
61%
29%
71%
NA
Source: ADB, 1993
Source: Ramani et al, 1993
3
This figures represent the percentages of villages electrified.
2
48
2
share of rural households
10%
80%
25%
22%
80%
6%3
2%
30%3
54%
18%
65%
3
15%
Figure 7.5. National electricity demand forecasts for the Netherlands
Table 7.3. Technical and non-technical losses
(in percent of net generation)
Technical
Non-technical
Total
Sri Lanka
14
4
18
Panama
17
5
22
Sudan
17
14
31
Bangladesh
14
17
31
Liberia
13
22
35
Malaysia
11
17
28
8
4
12
Ivory Coast
Source: M. Munasinghe et al., A review of World Bank Lending for Electric Power, World Bank,
Washington, DC, Energy Series Paper No. 2, p. 60.
49
Table 7.4. Distribution of technical energy losses (percent)
Madagascar Kenya Bangladesh Targeta
Power plant transformers
2.2
0.5
0.5
0.3
Transmission lines
2.7
5.2
2.2
3.8
Sub-stations
0.8
0.9
1.1
0.3
Primary lines
2.1
2.1
4.2
2.5
Distribution transformers and low tension network
4.2
6.3
6.0
1.5
12.0
15.0
14.0
8.3
Total
a
Target levels are those found in a relatively efficient, well-run system.
Source:
From:
IDEA, "Improving Power Sector Efficiency in Developing Countries," draft contractor
report to the Office of Technology Assessment, October 1990, p. 26.
Fuelling Development - Energy Technologies for Developing Countries, - Congress of
the United States Office of Technology assessment, 1992.
Table 7.5. Some typical fuel consumption rates for engine generators
Size (kW)
Fuel
Consumption rate
liters/kWh
Fuel operating costs
$/kWh
4.0
gasoline
0.71
0.71
7.5
gasoline
0.63
0.63
20
diesel
0.40
0.20
50
diesel
0.28
0.14
100
diesel
0.24
0.12
1,000
diesel
0.28
0.14
Note: both fuels priced at 50 US cents/litre.
50
Table 7.6. Initial capital costs of electricity generating systems
Technology
Engine generator:
- gasoline
- diesel
Note:
Size (kWp)
Initial capital cost ($kWp)
4.0
20.0
760
500
Micro-hydro
10-20
1,000-2,400
Photovoltaic
0.07
11,200
Photovoltaic
0.19
8,400
Wind turbine
0.25
5,500
Wind turbine
4
3,900
Wind turbine
10
2,800
Costs are for entire system, including conversion device, electric generator, and
associated electrical equipment. Prices for wind turbine and photovoltaic systems include
batteries. kWp ratings are for peak output, average output will be somewhat lower
depending on the resource. Prices for wind turbine, photovoltaic, and engine generators
are actual retail prices in the USA in 1990. Prices for micro-hydro are averages across
several installations.
Source: Fuelling Development - Energy Technologies for Developing Countries, - Congress of the
United States Office of Technology assessment, 1992.
Table 7.7. Operating, maintenance, and fuel costs for different technologies
used to generate electricity (diesel fuel price of $0.50/litre assumed)
Technology
O&M costs
Fuel costs
(cents/kWh)
(cents/kWh)
Engine generator
2
20 (diesel)
Micro Hydro
2
0
Photovoltaics
0.5
0
Wind turbines
1
0
Source: Fuelling Development - Energy Technologies for Developing Countries, - Congress of the
United States Office of Technology assessment, 1992.
51
Table 7.8. Approximate lifetimes of off-grid renewable generating technologies
Technology
Lifetime (years)
Engine Generator (diesel)
8-10
Micro Hydro
20-30
Photovoltaics
20-30
Wind Turbine
15-25
Batteries
3-5
Source: Fueling Development - Energy Technologies for Developing Countries, - Congress of the
United States Office of Technology assessment, 1992.
Table 7.9. Land requirements for power stations
Technology
dendro-thermal
solar thermal central receiver plant
solar thermal parabolic trough
pv concentrator
hydro
size (MW)
Area (m2)
50
300,000,000
1-10
6,216-71,084
80
16,800
0.025-0.3
245-11,880
24-12,600 96,000-42,000,000,000
km2/MW
6
0.007-0.01
0.021
0.009-0.013
0.004-9.1
Source: World Bank, 1994, Renewable Energy Technologies, A review of the status and costs of
selected technologies
Table 7.10. Estimates of annual electricity consumption, Bangkok (1989)
Appliance
Colour TV
Power
(W)
79
Usage
(hours/year)
2,014
Annual consumption
(kWh)
159
Refrigerator
109
5,760
628
Rice cooker
1,149
230
264
Clothes washer
1,567
91
143
- Window
1,815
1,442
2,617
- Central
2,257
1,564
3,530
77
2,061
159
4,418
54
239
Air conditioner:
Ceiling fan
Water heater
Source: Fueling Development: Energy Technologies for Developing Countries, Congress of the
United States Office of Technology assessment, 1992.
52
Table 7.11. Power rating of home energy appliances
Appliance
Power Rating
25-100 W
Incandescent bulbs
Fluorescent tube light
24°
48°(Slim light)
48°
20 W
36 W
40 W
Night lamp
5W
Mosquito repellent
5W
Fans
60 W
Air coolers
115 W
Air conditioners (1-1,5 ton)
1,000-1,500 W
Refrigerators (165 litres)
225 W
Mixer/blender/juicer
450 W
Toaster
800 W
Hot plate
1,000-1,500 W
Oven
Electric kettle
Iron
Water heater
- 1,1/2-2 litre capacity (Instant Geysers)
- 10-20 litre (Storage type)
- Immersion Rod
1,000 W
1,000-2,000 W
450-700 W
3,000 W
2,000 W
1,000 W
Vacuum Cleaner
700-750 W
Washing Machine
325 W
Water Pump
750 W
T.V.
60-120 W
Radio
15 W
Video
40 W
Tape Recorder
20 W
Stereo System
50 W
Source: Gujarat Energy Agency, India
53
8. TRANSPORTATION
Table 8.1. Energy efficiency of trucks in selected countries
Country/region
Truck name
Capacity
(metric tons)
Energy consumption
(MJ/tonne/km)
OECD
Mercedes
7.0
1.0
OECD
Man-VW 9136 (1980)
5.9
1.0
India
TATA 1201 SE/42
5.0
2.1
India
Ashok Leyland Beaver
7.5
1.6
China
Jiefang CA-10B
4.0
2.3
China
Dongfeng EQ140
5.0
1.8
Benz
1217
Note: OECD and Indian trucks use diesel, Chinese trucks use gasoline.
Source:
J. Yenny and L. Uy, World Bank, Transport in China, Staff Working Paper No. 723,
1985, p.70.
Table 8.2. Estimated traction power of animals operating farm equipment
Low Speed Traction
Type of animal
Weight
(kg)
Speed
(km/hr)
Force
(newton)
High Speed Traction
Power
(W)
Speed
(km/hr)
Force
(newton)
Power
(W)
Horse
light
385
2.4
435
290
4
396
440
medium
500
2.4
660
440
4
468
520
heavy
850
2.4
990
660
4
864
960
light
210
2.4
330
220
4
198
220
medium
450
2.4
660
440
4
468
520
heavy
900
2.4
1,215
810
4
864
960
light
400
2.4
550
370
3.2
416
370
medium
650
2.4
885
590
3.2
664
590
heavy
900
2.4
1,215
810
3.2
911
810
Bull
Water Buffalo
Source: K V Ramani, A K N Reddy, and M N Islam, “Rural Energy Planning: A Government
Enabled Market Based Approach”, APDC, Kuala Lumpur, Malaysia, 1995
54
9. ENERGY INTENSITY
Table 9.1. Energy consumption in the EU for the production of a number of products
product
resources
steel
aluminium
copper
zinc
alumina
ammonia
chlorine
soda ash
phosphor
methanol
oil products
petro-chemicals
styrene
VCM
poly-ethylene
poly-propylene
PVC
cement
building bricks
glass
paper
ore, scrap
alumina
ore, scrap
ore
bauxite
fossil fuels
salt
salt
ore
natural gas
crude oil
HC feedstocks
ethylene, benzene
ethylene, chlorine
ethylene
propylene
VCM
limestone
clay
sand, cullets
pulp, waste paper
*
production volume primary energy demand
(ktonne)
(PJ)
(% of total)
137,774
2635
5.7
2,319
369
0.8
1,266
14
0.0
1,719
67
0.1
4,900
72
0.2
12,479
443
1.0
8,490
287
0.6
5,750
75
0.2
240
40
0.1
2,000
34
0.1
463,725
1421
3.1
27,734
2237
4.8
3,000
27
0.1
4,360
36
0.1
5,955
36
0.1
2,440
29
0.1
3,930
23
0.1
171,922
665
1.4
47,760
133.5
0.3
20,410
181.9
0.4
35,010
778.0
1.7
*
energy intensity
(GJ/tonne)
19.1
159.1
11.1
39.0
14.7
35.5
33.8
13.0
166.7
17.0
3.1
80.7
9.0
8.3
6.0
11.9
5.9
3.9
2.8
8.9
22.2
Calculated by dividing the total primary energy demand by the production volume of a product
Source: Potentials for improved use of industrial energy and materials - E. Worrell, 1994
Table 9.2. Average energy intensities of building materials
Material
Source:
Energy intensity (MJ/kg)
Concrete aggregate
0.18
Concrete
0.8
Brick and tile
3.7
Cement
5.9
Plate glass
25.0
Steel
28.0
Mogens H. Gogand Kishore L. Nadkarni, "Energy Efficiency and Fuel Substitution in the
Cement Industry with Empahsis on Developing Countries, "World Bank Technical
Paper No. 17, Washington, DC, 1983.
55
10. GREENHOUSE GASES
Table 10.1. The principal greenhouse gases
CO2
concentration
pre-industrial
present
-1
radiative forcing per molecule (CO2 )
lifetime in atmosphere (years)
global warming potential1 relative to CO2
20 years
100 years
500 years
percentage contribution to
radiative forcing 1980-1990
current increase (per cent/year)
total
CH4
CFC-11 CFC-12
N2O
(ppmv)
280
353
(ppmv)
0.79
1,072
(pptv)
0
280
(pptv)
0
484
(ppbv)
280
310
1
21
12,400
15,800
206
50-200 14.5 +/- 2.5
65
130
120
4,500
3,500
1,500
7,100
7,300
4,500
290
320
180
1
1
1
62
24.5
7.5
55
15
24 (all CFC's)
0.5
0.9
4
6
0.25
Data from IPCC Working Group I, quoted in Climate Change and Energy Efficiency in Industry,
IPIECA, 1991
1
The warming effect of an emission of 1 kg of each gas relative to CO2 based on the present
day atmosphere. The figures for CH4 and N2O are those recently been revised by the IPCC and
not as in the original text.
56
Table 10.2. Emissions of pollutants from electric power generation: the total fuel cycle (a)
(tons per gigawatt hour)
Energy source
CO2
Conventional coal 1,058.2
Fluidised bed coal 1,057.1
Natural gas IGCC
824.0
Nuclear
8.6
Photovoltaic
5.9
Biomass
0(c)
Geothermal
56.8
Wind
7.4
Solar thermal
3.6
Hydropower
6.6
NO2
SO2
TSP(b)
CO
HC
2.986
1.551
0.251
0.034
0.008
0.614
TR(d)
TR(d)
TR(d)
TR(d)
2.971
2.968
0.336
0.029
0.023
0.154
TR(d)
TR(d)
TR(d)
TR(d)
1.626
1.624
1.176
0.003
0.017
0.512
TR(d)
TR(d)
TR(d)
TR(d)
0.267
0.267
NA
0.018
0.003
11.361
TR(d)
TR(d)
TR(d)
TR(d)
0.102
0.102
NA
0.001
0.002
0.768
TR(d)
TR(d)
TR(d)
TR(d)
Nuclear Total
waste
NA 1,066.1
NA 1,063.3
NA
825.8
3.641
12.3
NA
5.9
NA
13.4
NA
56.8
NA
7.4
NA
3.6
NA
6.6
notes:
a
: the total fuel cycle includes resource fuel extraction, facility construction and plant operation.
b
TSP: Total suspended particulates.
c
With biomass fuel regrowth program.
d
TR: trace elements.
NA: not applicable.
Sources:
(a) Meridian Corporation, Energy System Emissions and Material Requirements. Prepared for the Deputy
Assistant Secretary for Renewable Energy, US Department of Energy, Washington DC, February 1989,
pp. 25-29.
(b) Carbon dioxide data adapted by the Council for Renewable Energy Education from Dr. Robert L. San
Martin, Deputy Assistant Secretary for Renewable Energy, Environment Emissions from Energy
Technology Systems: The Total Fuel Cycle, US Department of Energy, Washington DC, spring 1989, p. 5.
Other emissions data from Assistant Secretary for Environment, Safety and Health, Energy Technologies
and the Environment, Environmental Information Handbook, Office of Environmental Analysis, US
Department of Energy, October 1988, pp. 333-334.
Table 10.3. Average CO2 emissions from selected fossil fuel sources
(tonnes per TJ of fuel burned)
Carbon
Coal2
24.2
Gas
13.8
Petrol
18.2
Diesel
18.8
Oil
19.8
CO21
88.7
50.6
66.7
68.9
72.6
Notes
1. NB 1 tonne of C combusts to give 3.667 tonnes of CO2
2. The amount of CO2 emitted from a given unit of coal will vary since the C content can be in the range
50-80%.
3. Limestone is frequently mixed with hard coal at combustion to control sulphur emissions which cause
acid rain. This practice serves to add a small increment to the CO2 output, though this effect has been
estimated to be no more than 0.4 tonnes CO2/TJ.
57
11. AIR EMISSION STANDARDS
Table 11.1. Exposure limits for a healthy indoor environment
agent
neighbour noise
radon
particulate matter (PM10)
benza-pyrene
benzene
lead in air
lead in drinking water
nitrogen dioxide
carbon monoxide
sulphur dioxide
ozone
formaldehyde
dichloro methane
Note:
reference value
+ 5 dB
-3
1 Bq.m EER; year
-3
-3
40 :g.m ; year, 140 :g.m ; 24 h
-3
1 ng.m ; year
-3
12 :g.m ; year
-3
0.5 :g.m ; year
-1
50 :g.L
-3
-3
300 :g.m ; 1 h, 150 :g.m ; 24 h
-3
-3
40 mg.m ; 1 h, 10 mg.m ; 8 h
-3
350 :g.m ; 1 h
-3
-3
150-200 :g.m ; 1 h, 100-120 :g.m ; 8 h
-3
120 :g.m ; 0.5 h
-3
1.7 mg.m ; 8 h
references
(WHO, 1987)
(RIVM, 1987)
(WHO, 1987)
(RIVM, 1987)
(GR, 1984)
(WLW, 1984)
(GR, 1979)
(GR, 1975)
(WHO, 1987)
(WHO, 1987)
(GR, 1984)
(RIVM, 1987)
Chemical agents of which exceeding the reference values indoors is not expected, is inevitable or
is considered to be not significant.
Table 11.2. Non-carcinogenic and carcinogenic agents
Agent
1,2-dichloroethane
acrylonitrile
arsenic
cadmium
carbon disulphide
external ionising radiation
hexavalent chromium
hydrogen sulphide
internal radiation in consequence of radon:
- in ambient air
- in construction material
manganese
mercury
styrene
sulphuric acid
tetrachloro ethane
toluene
trichloro ethane
vanadium
vinyl chloride
Carcogenic/
Non-Carcogenic
C
C
C
NC
NC
C
C
NC
C
C
NC
NC
NC
NC
NC
NC
NC
NC
C
Reference values
-3
36 :g.m ; year
-3
3.8 :g.m ; year
-3
20 ng.m ; year
-3
10 B 20 : gm ; year
-3
100 :g.m ; 24 h
mainly inevitable
-3
1 ng.m ; year
-3
150 :g.m ; 24 h
inevitable
mainly inevitable
-3
1 :g.m ; year
-3
1 :g.m ; year
-3
800 :g.m ; 24 h
(not considered significant)
-3
5 mg.m ; 24 h
-3
3 mg.m ; 24 h
-3
1 mg.m ; 24 h
-3
1 :g.m ; 24 h
-3
4,000-40,000 opt. fibres.m ; year
Source: Zorgen voor morgen (Cares for Tomorrow, National Environmental Assessment), Nationale
Milieuverkenning 1985-2010 - Rijks Instituut voor Volksgezondheid en Milieuhygiene (RIVM)
(Dep. of Health and Environment), 1989
58
Table 11.3. Air emission guidelines in the Netherlands
condition for emission-standard
a
emission-standard
when untreated mass-flow
is smaller/bigger than:
(gram/hour)
minimalisation-obligation for:
extremely hazardous pollutants:
polyhalogene-dibenzo-dioxines
polyhalogene-dibenzo-furanes
polychlorine-bifenyls
carcinogenic pollutants
mg/m
3
see end note c
carcinogenic material:
b
with threshold-value :
asbestos (cat. sA.1)
arsenic and -compounds (cat. sA.1), calculated as As
cadmium and -compounds ((cat. sA.1), calculated as Cd
formaldehyde (cat. O.1)
silica (silicon dioxide) fibres (cat. sA.1
0.10
0.20
0.20
20
0.20
> 1.0
> 1.0
> 100
> 1.0
without threshold-value:
category C.1
> 0.5
(compounds that are classified as carcinogenic based on epidemiological research)
benzo(a)anthracene
benzo(a)pyrene
benzo(b)fluoranthene
beryllium and -compounds, calculated as Be
chromium (VI) -compounds, calculated as Cr
benzo(j)fluoranthene
2-naphthylamine (+ salts)
benzo(k)fluoranthene
2-nitropropane
dibenzo(a,H)anthracene
category C.2
> 5.0
(compounds that are classified as carcinogenic based on chronic animal experiments)
3,3-dichloridebenzidine (+ salts)
dimethylsulphate
nickel and -compounds, calculated as Ni
category C.3
acrylo-nitrile
benzene
buta-1,3-diene
particulate matter (category S)
epi-chlorine-hydrine
hydrazine (+ salts)
< 500
> 500
a without filtering separator
b with filtering separator
particulate inorganic matter
category sA.1
1.0
ethylene-oxide
> 25
1,2-dibromine-methane
1,2-dichloro-ethane
0.10
> 1.0
5.0
propene oxide
vinyl-chloride
a
50b
10a
25b
10
0.20
mercury and inorganic mercury compounds, calculated as Hg
iron-penta-carbonyl
Silica fibres
platinum compounds, calculated as Pt
silver and -compounds, calculated as Ag
rhodium compounds, calculated as Rh
Asbestos fibres
thallium and -compounds, calculated as Tl
Arsenic and -compounds
vanadium compounds, calculated as V
Cadmium and -compounds
59
category sA.2
> 5.0
1.0
chromium-chloride
selenium and -compounds, calculated as Se
cobalt smoke and -compounds, calculated as Co
tellurium and -compounds, calculated as Te
silica (quartz) as respirable matter (excluding silica fibres) copper smoke, calculated as Cu
rhodium and not-water-soluble -compounds, calculated as Rh
lead and inorganic lead compounds, calculated as Pb
gaseous or vaporous inorganic matter
category gA.1
arsenic hydrogen (arsine)
chlorine cyanide
chlorine dioxide
> 10
1.0
phosphorus hydrogen (phosphine)
phosgene
category gA.2
> 50
5.0
bromide and -compounds, calculated as HBr
chlorine gas (Cl2)
hydrogen sulphide
fluorine and -compounds, calculated as HF
hydrogen cyanide
category gA.3
> 300
30
> 5,000
200
chlorine compounds, calculated as HCl
category gA.4
ammonia
nitrogen oxides, calculated as NO2
sulphur oxides, calculated as SO2
particulate organic matter
< 100
> 100
a without filtering separator
b with filtering separator
a
50b
10a
25b
10
category sO.1
alkyl-lead-compounds
maleic-acid-anhydride
organo-tin-compounds
di-phenyl-ether
methanol
propene acid
di-phenyl-methane-2,4-diisocyanate
propanol
methyl-amine
pyridine
benzyl chloride
2-methyl-aniline
sec-amyl acetate
biphenyl
methyl-bromide
1,1,2,2-tetra-chloro-ethane butyl acrylate
methyl-phenols
tetra-chloro-methane
chloro acetic acid
ethanol
methyl-(2-methyl)-propionate 2-chloro-ethanol
methyl-propionate
thio-alcohols
chloro-methane
1-methyl-2,4-phenylene-diisocyanate
1,1,2-trichloro-ethane
1-methyl-2,6-phenylene-diisocyanate
1,2-dichloro-methane
nitrobenzene
thio-ethers
tri-chloro-phenols
ftaal-acid-anhydride
nitro-cresols
tri-chloro-methane
2-furaldehyde
nitro-phenols
tri-ethyl-amine
60
aniline
anthracene
acetic acid-anhydride
di-methyl-amine
N,N-di-methyl-aniline
1,4-dioxin
nitro-toluenes
ethyl-amine
ethyl-propionate
phenol
formic acid
1,1-dichloro-ethylene
di-chlorine-phenols
di-ethylamine
category sO.2:
i-amyl-acetate
n-amyl-acetate
acetic acid
aromatic hydrocarbons
butanol
ethane
tri-chlorine-ethylene
tri-methyl-benzene
vinyl-acetate
vinyl-benzene
xylene
chlorine-benzene
category sO.3
aliphatic hydrocarbons
alkyl-alcohols
acetic-acid-ester
benzene
2-butanol
iso-butyl-acetate
n-butyl-acetate
chlorine-ethane
2-chloro-propane
2-chloro-1,3-butadiene
cyclo-hexanol
cyclo-hexane
1,4-dichloro-benzene
i-butanol
n-butanol
2-butanol
2-but-oxy-ethanol
butyl-lactate
carbon disulphide
ethyl benzene
di-butyl-ether
di-ethyl-ether
di-methyl-ether
1,2-ethane diol
ethanol-amine
ethylene
ethyl-acetate
ethyl-formate
2-hydroxy-methyl furan
2,2-imino-diethanol
iso-foron
iso-propenyl-benzene
iso-propyl-benzene
di(2-ethyl-hexyl)phthalate
N,N-dimethyl-acetamide
2,4-dimethyl-phenol
N,N-dimethyl-formamide
2,6-dimethyl-hepta-4-ol
2-ethoxy-ethanol
propane acid
4-hydroxy-4-methyl-2-methanol
2-iso-propoxy-propane
methanol
methyl-benzoate
3-methyl-2-butanol
n-methyl-pyrrolidine
4-methyl-2-pentanol
olefinic hydrocarbons
propanal
n-propyl-acetate
tetra-chloro-ethylene
tetra-hydro-furan
1,1,1-tri-chlorine2-methoxy-ethanol
methyl-acetate
methyl-benzene
methyl-cyclo-hexane
methyl-formate
naphthalene
paraffinic hydrocarbons
3-pentanol
2-pentanol
petroleum
pinenen
propanol
i-propyl acetate
gaseous or vaporous organic matter
category gO.1
> 100
20
category gO.2
> 2,000
100
category gO.3
> 3,000
150
a
the emission-standard quoted in the column "emission-standard" only applies when the massflow of the untreated gas meets the condition that it is bigger than the value as quoted in this
column
b
the minimal dose is below which no carcinogenic effects are to be expected
c
zero-emission should be target.
Source: Nederlandse Emissie Richtlijnen Lucht - Stafbureau NER (Netherlands Air Emission
Guidelines), 1992 e.v.
61
Table 11.4. U.S. National ambient air quality standards, 1988 (NAAQS)
Pollutant
Primary (health-based) standard
Averaging time
TSP
a
Concentration
annual geometric mean
b
24 hours
SO2
75 mg.m
-3
150 mg.m
annual arithmetic mean
CO
Secondary standard
c
same
-3
-3
80 mg.m (0.03 ppm)
-3
24 hours
365 mg.m (0.14 ppm)
3 hours
1300 mg.m (0.5 ppm)
8 hours
10 mg.m (9 ppm)
1 hour
40 mg.m (35 ppm)
-3
-3
c
-3
annual arithmetic mean
O3
daily max 1 hour avg
235 mg.m (0.12 ppm)
Lead
maximum quarterly avg
1.5 mg.m
Hydrocarbons
3 hours
160 mg.m (0.24 ppm)
b
c
-3
1300 mg.m (ppm)
-3
NO2
a
for 3 hours
100 mg.m (0.05 ppm)
same
-3
-3
-3
same
Total Suspended Particles
The geometric mean is obtained by taking the nth root of the product of n numbers. This
tends to reduce the impact of a few very large numbers in a set.
An arithmetic mean is the average determined by dividing the sum of a group of data points
by the number of points
Source: US EPA
Table 11.5. US automobile emission standards (grams per mile)
pollutant
1968
1985
1994
3.4
0.41
0.4
NOx
-
1.0
0.6
CO
34
3.4
10
Hydrocarbons
Source: US EPA
62
Table 11.6. Annual emissions of air pollutants, Lahore Pakistan, 1985
Particulates
Source
tonnes
%
SO2
tonnes
CO
%
tonnes
Hydrocarbons
%
tonnes
%
NOX
tonne
Aldehydes
%
tonnes
%
14,56
5
1,878
73
209
89
9
26
11
1,553
8
-
-
s
Motor
vehicles
Railway
2,014
26
1,377
49
123,054
96
29,536
91
171
2
756
27
657
-
447
1
54
1
5
-
193
-
51
Wood, coal,
solid waste
Industrial unit
1,119
14
302
11
4,622
4
1,569
5
3424
9
-
-
4,406
57
358
13
285
-
1,010
3
162
1
-
-
TOTAL
EMISSIONS
7,764
Natural gas
2,798
128,811
32,613
21,58
2
235
Source: UNIDO, 1994
Table 11.7. Estimated air pollutants from various economic sectors in Pakistan
(thousand tonnes)
1977/78
1987/88
1997/98
Sector
CO2
SO2
NOX
CO2
SO2
NOX
CO2
SO2
NOX
Industry
12,308
19
n/a
26,680
423
n/a
53,429
982
n/a
Transport
7,068
52
n/a
10,254
57
n/a
18,987
105
n/a
Power
3,640
4
3
11,216
95
n/a
53,062
996
76
Domestic
16,601
5
n/a
24,054
16
n/a
3,998
40
n/a
Agriculture
845
5
n/a
4,490
28
n/a
6368
40
n/a
Commercia
1726
11
n/a
2,587
13
n/a
4,261
25
n/a
l
n/a = not applicable
Source: UNIDO, 1994
63
Table 11.8. Emission standards in the Netherlands for waste burning installations
compound
total particulates
hydrochloric acid
fluorides
CO
organic compounds (as C)
SOx
NOx
emission standard (mg/m3)
5
10
1
50
10
40
70
heavy metals:
Sb+Pb+Cr+Cu+Mn+V+As+Co+Ni+Se+Te
Cd
Hg
Poly Chloro Dibenzo Dioxins
Poly Chloro Dibenzo Furans
1.0
0.05
0.05
0.1 ng/m3
0.1 ng/m3
Source: Combustion guidelines 1989; lowering air emissions - letter of Directorate Generale
Environment of Netherlands Ministry of Health and Environment to 12 provinces in
1989.
64
Table 11.9. Emission standards in the Netherlands for
heating systems, gas turbines and piston-engines
Heating systems
type
solid fuel
general
condition
>300MW th
<300MW th
liquid fuel
cokes-furnace gas
blast-furnace gas
refinery gas
liquid petrol gas
remaining gas
SO2
standard
3
(mg/m )
200
700
>300MW th
200
<300MW th
1,700
subcondition
400,
mw until 200
150,
mw until 120
C
800
5
35
NOx
particulate matter
substandard
substandard
3
3
condition
(mg/m ) condition (mg/m )
200
100
D
p, A
300
>50MW th 100 or 50
p, B
150
<50MW th no standard
b, A
300
b, B
110
p
100
20
60
Gas turbines and gas turbine installations
g NO2/GJ
200 0/30
65 0/30
gas turbines
gas turbine installations
Piston engines
gas engines
NOx condition
>50kW
<50kW
diesel engines
>50kW
<50kW
A
B
C
D
p
b
0
mw
g NO2/GJ
140 0/30
mw until 100 0/30
800 0/30
mw until 270 0/30
400 0/30
mw until 150 0/30
1200 0/30
mw until 400 0/30
liquid fuel generated inside the plant N>0.3%
remaining liquid fuels
gas from a refinery
dependent on ash-content of the fuel
process-furnaces
boiler
gas-turbine or engine efficiency
margin width: the licence authority has freedom to dictate stricter standards (with the indicated
limit) when a specific situation requires this
Source: Guidelines "Act Emission Norms Combustion Installations" A - Dumas and Mulder-Bakker,
Netherlands Min. of Environment, 1993
65
Table 11.10. Review of Dutch boundary, guide and target values of pollutants
name of matter
acrolein; propenal
acrylo nitrile; ethylene-nitrile
benzene
1,2-dichloro-ethane
di-chlorine-methane; methylenechloride
ethylene
1,2-epoxy ethane
phenol
fluorides
formaldehyde; methanol
carbon-monoxide
lead
methyl-bromide; brominemethane
ozone
boundary
value
20
4
1
10
guide
value
120
12
2.8
0.8
0.4
100
40
30
6,000
40,000
2
0.5
0.1
annual average
1
1
annual average
annual
average
99.99 percentile (hourly average)
0.03
1
1
100
240
120
benzo(a)pyrene
propylene-oxide; propyl-oxide;
1,2-epoxy propane
nitrogen-dioxide
styrene
tetra-chlorine-ethylene
tri-chlorine-ethylene
tri-chlorine-methane; chloroform
vinyl chloride; chlorine-ethylene
sulphur-dioxide
sulphur-hydrogen
particulate matter; black smoke
0.005
1
0.0005
135
175
80
2,000
8,300
1,000
50
300
75
200
250
2.5
30
75
90
150
remark
99,99 percentile (hourly average)
20
300
30
target
value
25
8,300
30
80
100
annual
average
8
25
50
1
1
annual average
annual average
daily average
monthly average
growth-seasonally average
99.99 percentile (hourly average)
98 percentile (24 hourly average)
95 percentile (24 hourly average)
98 percentile (8 hourly average)
99.99 percentile (hourly average)
98 percentile (24 hourly average)
annual average
annual average
hourly average
hourly average, max. 5 d/a
exceeding
hourly average, max. 1 d/a
exceeding
annual average
98 percentile (hourly average)
99.5 percentile (hourly average)
50 percentile (hourly average)
annual average
annual average
98 percentile (hourly average)
99.5 percentile (hourly average)
annual average
98 percentile (hourly average)
annual average
annual average
50 percentile (24 hourly average)
95 percentile (24 hourly average)
98 percentile (24 hourly average)
99.5 percentile (hourly average)
50 percentile (24 hourly average)
95 percentile (24 hourly average)
98 percentile (24 hourly average)
24 hourly average
Source: Nederlandse Emissie Richtlijnen - NER (Netherlands Emission Standards), June 1991
66
Table 11.11. Estimated emission factors of selected fuels
Fuel
TSP
d<10µ
µm
3
(mg/m )
4-20
CO2
CO
Wood
Heating
Value
(MJ/kg)
16
HCs
(Vol %)
8
(mg/m )
12-156
(ng/m )
1300
(mg/m )
0.31
(mg/m )
0.16
Dung
12.5
5-80
-
17-175
8200
0.14
0.24
Charcoal
30
5.5
-
-
-
0.075
0.83
Coal (Indian)
23
24.9
-
-
4200
0.17
1.7
3
NO2
3
SO2
3
3
Source: K R Smith, “Air, Health and Pollution”, 1987, quoted in “Manual on Simple Monitoring Techniques
for the Control of Indoor Air and Combution Quality Standards in Developing Countries”, J
Usinger, WHO/HEP-GTZ, 1996.
Table 11.12. WHO standards for health affecting limits of various pollutants
Pollutant
Carbon Monoxide
Formaldehyde
Lead
Nitrogen dioxide
Ozone
Sulphur dioxide
Suspended Particles
Thoracic Particles
Benzene
Asbestos
Radon
Tobacco smoke
Concentration
3
100 mg/m
3
60 mg/m
3
30 mg/m
3
10 mg/m
3
100 µg/m
3
1 µg/m
3
400 µg/m
3
150 µg/m
3
200 µg/m
3
120 µg/m
3
500 µg/m
3
350 µg/m
3
125 µg/m
3
120 µg/m
3
70 µg/m
3
2.5 µg/m
3
500 fibres/m
100 Bq
as little as feasible
Time limit
15 min
30 min
1 hour
8 hours
30 min
1 year
1 hour
24 hours
1 hour
8 hours
10 min
1 hour
24 hours
24 hours
24 hours
1 year
1 year
1 year
not inside bedroom of young children or the sick
Source: Quoted in “Manual on Simple Monitoring Techniques for the Control of Indoor Air and
Combustion Quality Standards in Developing Countries”, J Usinger, WHO/HEP-GTZ, 1996.
67
Table 11.13. Comparison of smoke exposures and concentrations due to
traditional and improved cook stoves in South Asia: summary of studies
Location
pollutant
Traditional Stoves
number
mean
Nepal (personal monitoring)
Two mid-hill villages
TSP
22
India (personal monitoring)
Two Gujarat villages
TSP
21
BAP
21
Four Gujarat villages
TSP
21
a
One Harayana village
TSP
51
Two Karnataka
TSP
39
a,b
villages
Nepal (area monitoring)
Two mid-hill villages
CO
27
c
7-day means
(kitchen)
NO2
5
(bedroom)
NO2
4
(kitchen)
HCHO
5
(bedroom)
HCHO
4
Nepal, Kathmandu valley (simulated cooking)
old stoves
CO
16
new, well installed
CO
28
stoves
3.14 mg/m
3
Improved Stoves
number
mean
3
stat.
variance
date
<0.5%
1986
27
1.13 mg/m
6.4 mg/m
3
3.7 µg/m
3
3.6 mg/m
3
3.2 mg/m
3
3.5 mg/m
14
14
23
36
40
4.6 mg/m
3
2.4 µg/m
3
3.9 mg/m
3
2.8 mg/m
3
2.6 mg/m
n.s.
n.s.
n.s.
n.s.
n.s.
1983
300 ppm
26
67 ppm
<0.1%
1986
0.26 ppm
0.02 ppm
0.33 ppm
0.04 ppm
5
4
4
4
0.04 ppm
0.04 ppm
0.04 ppm
0.13 ppm
<1.0%
n.s.
n.s.
n.s.
1986
600 ppm
400 ppm
28
11
400 ppm
100 ppm
<5%
<0.5%
1985
1985
3
3
1987
1987
1987
Notes: Except where noted all measurements were taken during the cooking period in the dry season
either by use of personal monitoring equipment worn by the cook or with stationary monitors
placed nearby.
HCHO Formalehyde
n.s.
not significant, that is less than 0.5%
a
These measurements were taken in all three major seasons (summer, winter, monsoon).
b
Also measured were exposures of women cooking with traditional
stoves placed under a
3
fireplace-style hood. With 24 measurements, the mean was 1.6 mg/m , which is significantly lower
than either the traditional stove or the improved stove in the same village (p<1%).
c
The p value for combined kitchen and bedroom NO2 concentrations in homes with traditional
versus improved stoves is <2.5% while that for HCHO is not significant.
Source: K Smith, “Biofuels, Air Pollution, and Health: A Global Review”, Plenum Press, New York, 1987,
quoted in K V Ramani, A K N Reddy, and M N Islam, “Rural Energy Planning: A Government
Enabled Market Based Approach”, APDC, Kuala Lumpur, Malaysia, 1995
68
Table 11.14. Nominal particulate dose commitment and dose-equivalent energy
for alternative cooking methods
Coal Power Plant and Electric Stove
Conversion
Quantity
Factor
1.0 MJ Heat
Energy into pot
Stove Efficiency
80%
1.2 MJ Heat
Transmission
80%
1.6 MJ Heat
Conversion
30%
5.2 MJ Heat
Density
20 MJ/kg
Emission Factor
Flue gas control
Dose commitment or
b
Dose-equivalent energy
Wood Fuel Cook stove
Conversion
Quantity
Factor
1.0 MJ Heat
20%
5.0 MJ Heat
0.3 kg Coal
15 MJ/kg
0.33 kg Wood
200 g/kg
52 g TSP
2 g/kg
0.66 g TSP
85%
8.0 g TSP
0
0.66 g TSP
2.5 g/t
-4
1,200 g/t
1 x 10 g/MJ or
1000 MJ/g
0.2 x 10 g/MJ or
50,000 MJ/g
-3
Notes
a Dose commitment = (Dose equivalent energy) - 1 = grams particulates inhaled by humans per unit
useful energy; in this case MJ heat into cook pot.
b Dose equivalent energy = (Dose commitment) - 1 = MJ useful energy per gram of inhaled particulates.
Source: K Smith, “Biofuels, Air Pollution, and Health: A Global Review”, Plenum Press, New York, 1987,
quoted in K V Ramani, A K N Reddy, and M N Islam, “Rural Energy Planning: A Government
Enabled Market Based Approach”, APDC, Kuala Lumpur, Malaysia, 1995
Table 11.15. Nominal dose commitments for RSP, CO, NOX, and HCHO
resulting from cooking one meal on an unvented stovea
Stove
Wood fired
c
Gas
d
Kerosene
b
RSP
(mg)
17.0
0.012
4.2
CO
(mg)
340.0
5.9
58
NOX
(mg)
8.5
0.27
1.5
HCHO
(mg)
0.69
0.05
0.069
Notes
HCHO =3 Formalehyde
a 40 m kitchen, 5 ACH, 1.5 hour cooking period, one burner in use
b Wood stove: 2 kg/h, 15 MJ/kg, 10% efficient, 135 mg/MJ-RSP, 2700 mg/MJ-CO, 68 mg/MJ NOX, 2.7
mg/MJ HCHO. Mixing behaviour lower exposures by 50%.
c Gas stove: 3.8 MJ/h, 80% efficient, 0.4 mg/MJ RSP. 200 mg/MJ-CO. 9.0 mg/MJ NOX, 1.7 mg/MGHCHO.
d Kerosene Stove: (RSP and CO measurements of Nutun cook stove, others from highest reported
levels for kerosene heaters): 5.0 MJ/h, 60% efficient, 64 mg/MJ RSP, 920 mg/MJ-CO, 26 mg/MJ NOX,,
1.2 mg/MG-HCHO.
Source: K Smith, “Biofuels, Air Pollution, and Health: A Global Review”, Plenum Press, New York, 1987,
quoted in K V Ramani, A K N Reddy, and M N Islam, “Rural Energy Planning: A Government
Enabled Market Based Approach”, APDC, Kuala Lumpur, Malaysia, 1995
69
Table 11.16. Kerosene stove emission factors (g/kg)
Date of quoted study
1982
1983
1983
1984
1984
1984
1985
1985
1987 (1)
1987
Stove type
Radiant and convective
Radiant
Radiant
Convective
Multi-stage
Radiative
Convective
Kerosene
Nutan
Wood fired
TSP
0.06
0.01
a
0.022
a
0.017
5.0
2.8
2.0
CO
3.2
2.8
4
5.5
4.4
5.7
0.03
0.06
-
HCHO
0.05
-
NO2/NO
0.7/0.7
0.6/0.5
0.5-0.7
0.2/0.07
0.1
0.16/0.06
0.13/0.7
0.11/0.27
-
67
41
40
-
-
0.4
0.5
Notes
All studies except (1) relate to unvented space heaters.
Original units in square brackets which have been converted into common unit (g/kg).
Kerosene has net energy of 43.5 MJ/kg and a mass density of 0.78.
HCHO = Formaldehyde
a Total PAH from radiant heater found to be 0.04 mg/kg and from convective heater 0.005 mg./kg. This
compares with about 1.0 mg/kg for BaP alone in wood combustion.
Source: K Smith, “Biofuels, Air Pollution, and Health: A Global Review”, Plenum Press, New York, 1987,
quoted in K V Ramani, A K N Reddy, and M N Islam, “Rural Energy Planning: A Government
Enabled Market Based Approach”, APDC, Kuala Lumpur, Malaysia, 1995
Table 11.17 Conversion of ppm to mg/m3 and vice versa
Gas
Carbon monoxide CO
Nitrogen dioxide NO2
Sulphur dioxide SO2
Formaldehyde HCHO
Benzol C6H6
Mass of mol (g/mol)
28
46
64
30
78
Factor to convert
3
ppm into mg/m
1.16
1.91
2.66
1.25
3.25
Factor to convert
3
mg/m into ppm
0.86
0.52
0.37
0.8
0.31
Example
3
The level of Carbon Monoxide in a flue gas exhaust was found to be 10 mg/m . The corresponding ppm is
given by: 0.86 x 10 = 8.6 ppm.
3
The formaldehyde level was found to be 0.3 ppm. The corresponding concentration in mg/m is given by:
3
1.25 x 0.3 = 0.375 mg/m .
Source: J Usinger, “Manual on Simple Monitoring Techniques for the Control of Indoor Air and
Combustion Quality Standards in Developing Countries” , WHO/HEP-GTZ, 1996.
70
12. GLOSSARY OF ENERGY AND ENVIRONMENTAL TERMS
Acid rain or acid deposition
A complex chemical and atmospheric phenomenon that occurs when emissions of sulphur and
nitrogen compounds and other substances are transformed by chemical processes in the
atmosphere, often far from the original sources, and then deposited on earth in either a wet or dry
form. The wet forms, popularly called acid rain, can fall as rain, snow or fog. The dry forms are
acidic gases or particulates.
Active solar energy
The advanced use of sunshine through solar photovoltaic or solar thermal conversion
technologies.
Air quality standards
The level of pollutants prescribed by regulations that may not be exceeded during a specified time
in a defined area.
Agricultural residues
By-products of the agricultural production system, including straws, husks, shells stalks and
animal dung, with a large number of uses, including an energy resource. Residues can be
divided into two groups: crop residues, which remain on the field after harvest, for example,
cotton stalks; and agro-processing residues, produced off-field at a central production sight, for
example, rice husk.
Agro-processing residues
See under agricultural residues.
Alternative energy system
A phrase used to describe new energy technologies and production processes that are seen as
alternatives for traditional and conventional energy sources.
Anaerobic digestion
The natural process of decomposition of organic material by bacteria under anaerobic conditions
(i.e. in the absence of oxygen), a by-product of which is biogas.
Animate energy (or power)
Utilisation of human and animal muscles to do work.
Assimilation
The ability of a body of water to purify itself of pollutants.
Base load
The average minimum demand on an electricity system, usually measured over a 24 hour cycle.
Basel Convention
The Basel Convention on the Control of Trans-boundary Movements of Hazardous Wastes and
their Disposal (1989) aims to control the trans boundary movement and disposal of hazardous
wastes.
71
Biochemical oxygen demand (BOD)
A measure of the amount of oxygen consumed in the biological processes that break down
organic matter in water. The greater the BOD, the greater the pollution.
Biocoal
Compacted solid fuel made from carbonised wood waste or low ash agro-residues.
Biodegradability
The ability to break down or decompose rapidly under natural conditions and processes.
Bio-diesel
Modified (trans-esterified) vegetable oils, such as soya bean, palm oil, jatropha, which have
similar chemical properties to diesel and therefore can be used as a direct substitute.
Biodiversity
Biological diversity, the variety of species within a given area.
Biogas
A mixture of gases consisting of around 60 to 70% of methane (depending on conditions)
produced by the process of anaerobic digestion in a closed container (digester). Biogas burns with
similar properties to natural gas.
Biological magnification
Refers to the process whereby certain substances such as pesticides or heavy metals move up
the food chain, work their way into a river or lake and are eaten by large birds, animals or
humans. The substances become concentrated in tissues or internal organs as they move up the
chain.
Biological oxidation
The way bacteria and micro-organisms feed on and decompose complex organic materials. Used
in self-purification of water bodies and in activated sludge waste-water treatment.
Biological treatment
A treatment technology that uses bacteria to consume waste. This treatment breaks down organic
materials.
Biomass
A generic term to describe all forms of organic matter including wood, agricultural waste, animal
dung and human waste. The term can be extended to include derivatives, such as ethanol, which
can be used as fuels. (The scientific definition is the total dry organic matter or stored energy
content of living organisms in a given area.)
Biosphere
The portion of the earth that supports life, including the surface waters and the air. Similar to
ecosphere.
Biotechnology
Techniques that use living organisms or parts of organisms to produce a variety of products, from
medicines to industrial enzymes, to improve plants or animals or to develop micro-organisms for
specific uses such as removing toxins from bodies of water or killing pests.
72
Briquetting
Densification of loose organic material, such as rice husk, sawdust, coffee husks, to improve fuel
characteristics including handling and combustion properties.
Brundtland Report
Popular name for report produced in 1987 by the World Commission on Environment and
Development. This United Nations-sponsored body produced a global agenda for change and
specified how sustainable development could be achieved. The commission was chaired by Gro
Harlem Brundtland, the then – and subsequently re-elected – prime minister of Norway.
Cadmium
Toxic heavy metal used mainly for metal plating and as a plastic pigment. Significant by-product in
zinc smelting and of concern in phosphate manufacture.
Capacity factor
The actual output of a technology divided by the theoretical maximum output of the technology
operating at peak design resource levels.
Capital cost
The investment in plant and equipment, including construction costs but not operation,
maintenance or energy costs.
Carbon cycle
The circulation of carbon in the biosphere. Carbon is an essential part – a building block – of the
molecules that make up all living cells. In the atmosphere it circulates as carbon dioxide, which is
released by respiration, combustion and decay and fixed in complex carbon compounds during
photosynthesis in plants and certain micro-organisms.
Carbon dioxide (CO2)
A colourless, odourless, non-poisonous gas that results from respiration, combustion and decay
and is normally present in ambient air.
Carbonisation
The heating of biomass in the absence of air to remove the volatile component, leaving a solid
high carbon product, charcoal.
Carbon sink
See Sink.
Carcinogen
Any substance that can cause or contribute to the onset of cancer.
Catalytic converter
An air pollution abatement device that removes pollutants from motor vehicle exhaust, either by
oxidising them into carbon dioxide and water or reducing them to nitrogen and oxygen.
Chemical oxygen demand (COD)
A measure of oxygen required to oxidise all compounds in water, both organic and inorganic.
73
Chlorofluorocarbons (CFCs)
A family of inert, non-toxic and easily liquefied chemicals used in refrigeration, air conditioning,
packaging and insulation or as solvents and aerosol propellants. Because CFCs are not
destroyed in the lower atmosphere they drift into the upper atmosphere, where their chlorine
components destroy ozone.
Cleaner production
A concept of industrial production that minimises all environmental impacts through careful
management of resource use, of product design and use, systematic waste avoidance and
management of residuals, safe working practices and industrial safety. Sometimes called pollution
prevention or waste minimisation.
Clean technologies
Production processes or equipment with a low rate of waste production. Treatment or recycling
plants are not classed as clean technologies.
Co-generation
Sequencial production of both heat and power using the same fuel. An example is the use of
expanded steam left over after generating electricity for heating purposes. The concept is applied
extensively in many wood and agro-processing industries (such as, sugar and palm oil mills).
Combined Heat and Power (CHP) Generation
Simultanous production of both heat and power. The difference with co-generation is that the
generation of heat and power may be done as parallel processes, which results in a lower overall
efficiency.
Combustion
Chemical reaction between a fuel and oxygen which usually takes place in air. More commonly
known as burning. The products are carbon dioxide and water with the release of heat energy.
Commercial energy
Energy traded in the market for a monetary price, usually conventional energy, such as coal or oil,
but also traditional energy, such as fuelwood, which is traded in urban and semi-urban areas in
many developing countries.
Coppicing
Technique of utilising the ability of some trees species to re-generate from the stump after a
cutting.
Cradle-to-grave
Term used to imply the whole life cycle of a product, from raw material to final disposal.
Crop residues
See under agricultural residues.
Decentralised energy systems
Small scale energy producing facilities deigned to meet local demand only.
Demand side management
The planning, implementation and monitoring of activities designed to encourage consumers to
modify their pattern of energy use.
74
Dendropower
The conversion of wood energy to electricity or shaft power.
Dilution ratio
The relationship between the volume of water in a stream and the volume of incoming water. If
affects the ability of the stream to assimilate waste.
Dioxin
Any of a family of compounds known chemically as dibenzo-p-dioxins. They are of concern
because of their potential toxicity and contamination in commercial products. Tests on laboratory
animals indicate that dioxins are among the more toxic man-made chemicals known.
Disposal
Final placement or destruction of toxic, radioactive or other wastes; surplus or banned pesticides
or other chemicals; polluted soils; and drums containing hazardous materials from removal
actions or accidental releases. Disposal may be accomplished through use of approved secure
landfills, surface impoundments, land farming, deep well injection, ocean dumping or incineration.
Dissolved oxygen (DO)
The oxygen freely available in water. Dissolved oxygen is vital to fish and other aquatic life and for
the prevention of odours. Traditionally, its level has been accepted as the single most important
indicator of a water body's ability to support desirable aquatic life. Secondary and advanced waste
treatment are generally designed to protect DO in waste-receiving waters.
Dump
A site used to dispose of solid wastes without environmental controls.
Eco-efficiency
Maximization of industrial output from a given level of resource input, thus ensuring waste
minimisation and appropriate use of human, renewable and non-renewable resources.
Ecology
The relationship of living things to one another and their environment, or the study of such
relationships.
Ecologically sustainable industrial development (ESID)
Patterns of industrialisation that enhance the contribution of industry to economic and social
benefits for present and future generations without impairing basic ecological processes.
Ecosystem
The interacting system of a biological community and its non-living environmental surroundings.
End-of-pipe treatment (abatement)
Treating pollutants at the end of a process (by, for example, filters, catalysts and scrubbers)
instead of preventing their occurrence.
End-use
The final use of energy at the level of the user, for example, lighting, cooking, space-heating and
motive power.
Energy
Capacity (or ability) to do work.
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Energy auditing
A systematic method of identifying and accounting for energy flows through an industrial
system or process to assist in identifying options to reduce energy use.
Energy balance
An energy balance is a set of relationships accounting for all the energy which is produced and
consumed, and matches inputs and outputs, in a system over a certain time period. The system
can be a country, a region, a village, a farm, a household, a factory, or a process.
Energy carrier
A liquid, gaseous or solid fuel or electricity to provide energy.
Energy convertor
Device, process of system which transforms energy from one form into another, for example,
diesel engine, generator, electric motor, water pump.
Energy efficiency
Conversion ratio of output and input energy of energy production technologies and end-use
appliances.
Energy equivalent
Theoretical value comparing energy contents of two different fuels, not including differences in
transformation efficiencies.
Energy intensity
Amount of energy needed per unit of physical or monetary output.
Energy need
Actual end-need for which energy is required, for example, illumination, mobility, warmth.
Energy replacement value
The amount of a particular energy form which in practice is needed to do the same job as another
energy form or fuel.
Energy service
View of energy as a resource to perform a desired task to meet end-needs
Environment
The sum of all external conditions including physical and social factors, affecting the life,
development and survival of an organism.
Environmental compliance audit
Systematic review and testing by professional environmental auditors of the management,
production, marketing, product development and organisational systems of an enterprise to
determine and assess compliance with environmental regulations.
Environmental impact assessment
An analysis to determine whether an action would significantly affect the environment.
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Eutrophication
The slow ageing process in which a lake, estuary or bay becomes a bog or marsh and eventually
disappears. During the later stages, or eutrophication, the water body is choked by overabundant
plant life as the amounts of nutritive compounds such as nitrogen and phosphorus increase.
Human activities can accelerate the process.
Expressed demand
Equal to consumption. Demand that is expressed in relation to energy supply availability and the
user’s purchasing power or physical capacity to acquire.
Externality
The cost or benefits to parties other than the supplier and purchaser of an economic transaction.
FAO
Food and Agricultural Organisation of the United Nations.
Feedback
When a change in one variable in a system, for example, increase in temperature, triggers
changes in a second variable, such as cloud cover, which in turn ultimately affects the original
variable, that is, increasing or diminishing the warming. A positive feedback intensifies the initial
change, a negative feedback reduces the initial change.
Final energy
Energy which the consumer buys or receives to perform a desired task with an end-use device.
Fossil fuels
The non-renewable energy resources of coal, petroleum or natural gas or any fuel derived from
them. Exploitation of new reserves has a long development period.
Fuel wood
Trunks and branches of trees as well as residues from wood processing industries and
scrapwood which are used as an energy source, largely through direct combustion.
Gasification
Conversion of solid fuels (biomass and coal) at high temperatures in the absence of air to give
combustible gases.
Generating capacity
The capacity of a power plant to generate electricity, often expressed in watts-electric (e.g. MWe).
GDP
Gross Domestic Product. The total market value of all the goods and services produced within a
nation (excluding income from abroad) during a specified period.
GEMS
Global Environment Monitoring System, managed by UNEP. Makes comprehensive assessments
of major environmental issues and thus provides the scientific data needed for the rational
management or natural resources and the environment, provides early warning of environmental
changes by analysing monitoring data.
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Global warming
The consequences of the greenhouse effect, caused by rising concentrations of greenhouse
gases. The suspicion is that global warming will disrupt weather and climate patterns. It could lead
to drought in some areas and flooding in others. One of the most serious environmental problems
facing the world.
GNP
Gross National Product. The local market value of all the goods and services produced by a
nation (including income from abroad) during a specified period.
Good housekeeping
Efficient management of the property and equipment of an institution or organisation. In the
context of Cleaner Production, it often refers to the procedures applied in the operation of a
production process.
Greenhouse effect
The warming of the earth's atmosphere, caused by a build-up of carbon dioxide or other trace
gases. It is believed by many scientists that this build-up allows light from the sun's ray to heat the
earth but prevents a counterbalancing loss of heat.
Greenhouse gases
The gases, such as carbon dioxide, water vapour, methane, nitrous oxides and CFCs, that trap
the sun's heat in the lower atmosphere and prevent it from escaping into space. Major source of
increased concentration in the atmosphere is the combustion of fossil fuels. See Greenhouse
effect.
Gross Energy Requirement (GER)
Total energy input required for one unit of product
Groundwater
The supply of fresh water found beneath the earth's surface (usually in aquifers) that is often used
for supplying wells and springs. Because groundwater is an important source of drinking water,
there is growing concern about areas where agricultural or industrial pollutants or substances from
leaking underground storage tanks are contaminating groundwater.
Halons
Bromine-containing compounds with long atmospheric lifetimes whose breakdown in the
stratosphere can cause depletion of ozone. Halons are used in fire-fighting.
Hazardous waste
By-products of society that can pose a substantial hazard to human health or the environment
when improperly managed. Characterised by at least one of the following: ignitability, corrosivity,
reactivity or toxicity.
Heavy metals
Metallic elements with high atomic weights, e.g. mercury, chromium, cadmium, arsenic and lead.
They can damage living organisms at low concentrations and tend to accumulate in the food
chain.
Hydrocarbon (HC)
Chemical compounds consisting entirely of carbon and hydrogen.
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IE/PAC
Industry and Environment Programme Activity Centre of UNEP, in Paris; formerly called the
Industry and Environment Office.
IEA
International Energy Agency of the OECD
Incineration
1. Burning of solid, liquid or gaseous materials.
2. A treatment technology involving destruction of waste by controlled burning at high
temperature, e.g. burning sludge to remove the water, to reduce the remaining residues to a
safe, non-combustible ash that can be disposed of safely on land, in some waters or in
underground locations.
INEM
International Environmental Management Association. Co-ordinates and supports national
associations of environmentalist business management associations or business enterprises.
Described in the European Community publication Business and Environment.
IPCC
Intergovernmental Panel on Climate Change.
IRPTC
International Register of Potentially Toxic Chemicals, at Geneva. A co-operative activity of
UNEP/WHO/ILO. Maintains a global system for assessing environmental effects of chemicals.
Topics include identification of knowledge gaps; chemical hazards; evaluation and control of
chemicals in the environment; numerical data; production, use and characteristics of chemicals;
laws and regulations affecting man, living species and natural resources.
Landfills
1. Sanitary landfills are land disposal sites for non-hazardous solid wastes, where the waste is
spread in layers, compacted to the smallest practical volume and cover material applied at the
end of each operating day.
2. Secure chemical landfills are disposal sites for hazardous waste. They are selected and
designed to minimise the chance of hazardous substances being released into the environment.
Leachate
A liquid produced when water collects contaminants as it trickles through wastes, agricultural
pesticides of fertilisers. Leaching may occur in farming areas, feedlots or landfills and may result
in hazardous substances entering surface water, groundwater or soil.
Life cycle cost
The cost of a good or service over its entire life cycle.
Mercury
A heavy metal that can accumulate in the environment and is highly toxic if breathed or swallowed. See Heavy metals.
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Minimisation
Actions to avoid, reduce or in other ways diminish the hazards of wastes at their source. Recycling
is, strictly speaking, not a minimisation technique but is often included in such programmes for
practical reasons.
Monoculture
The exclusive cultivation of a single species, a common practice in modern agriculture and
forestry.
Montreal Protocol
The Montreal Protocol on Substances that Deplete the Ozone Layer, adopted 16 September
1987, sets limits for the production and consumption of damaging CFCs and halons.
NIMBY
Acronym for "not in my back yard." Political jargon to describe a situation in which the electorate
might agree to, say, industrial dumping or incineration, as long as it does not take place near their
homes.
Nitrate
A compound containing nitrogen that can exist in the atmosphere or as a dissolved gas in water
and that can have harmful effects on humans and animals. Nitrates in water can cause severe
illness in infants and cows.
Non-commercial energy
Energy which does not have a monetary price, usually refers to fuelwood, agricultural residues or
animal waste, which are self collected or traded through barter.
Non-point source
Pollution sources that are diffuse and do not have a single point of origin or are not introduced into
a receiving stream from a specific outlet. The pollutants are generally carried off the land by
storm-water run-off. The commonly used categories for non-point sources are agriculture,
forestry, urban areas, mining, construction, dams and channels, land disposal and salt-water
intrusion.
Non-renewable energy
Any form of primary energy, the supply of which is finite and hence its use depletes the existing
stock. It generally refers to fossil fuels.
Non-woody biomass
Stalks, leaves, grass, animal and human waste.
NOx
Chemical formula that stands for all the oxides of nitrogen, mainly NO2, but also N2O, NO, N2O3,
N2O4 and NO3, which is unstable.
Nutrient
Any substance assimilated by living organisms that promotes growth. The term is generally
applied to nitrogen and phosphorus in waste water but is also applied to other essential and trace
elements.
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Off-site facility
A hazardous waste treatment, storage or disposal area that is located away from the generating
site.
Ozone (O3)
Found in the lower layers of the atmosphere, the stratosphere and the troposphere. In the
stratosphere (the atmospheric layer beginning 7-10 miles above the earth's surface), ozone is a
form of oxygen found naturally which provides a protective layer, shielding the earth from
ultraviolet radiation's harmful health effects on humans and the environment. In the troposphere
(the layer extending up 7-10 miles above the earth's surface), ozone is a chemical oxidant and a
major component of photochemical smog. Ozone can seriously affect the human respiratory
system and is one of the most prevalent and widespread pollutants. Ozone in the troposphere is
produced through complex chemical reactions between nitrogen oxides, which are among the
primary pollutants emitted by combustion sources, hydrocarbons, which are released into the
atmosphere by the combustion, handling and processing of petroleum products, and sunlight.
Ozone depletion
Destruction of the stratospheric ozone layer, which shields the earth from ultraviolet radiation
harmful to life. This destruction of ozone is caused by certain chlorine- and/or bromine-containing
compounds (chlorofluorocarbons or halons), which break down when they reach the stratosphere
and catalyse the destruction of ozone molecules.
Passive solar energy
The direct use of natural sunshine for lighting, heating or convective ventilation in buildings in
order to replace conventional conversion technologies.
PCBs
A group of toxic, persistent chemicals (chemical name: polychlorinated biphenyls) used in
transformers and capacitors for insulating purposes and in gas pipeline systems as a lubricant.
Peak load
The average maximum power demand on an energy system, especially for electricity generation,
over a period of time, usually a 24 hour cycle.
Phenols
Organic compounds that are by-products of petroleum refining, tanning and the manufacturing of
textiles, dyes and resins. Low concentrations cause taste and odour problems in water; higher
concentrations can kill aquatic, animal and human life.
Phosphates
Certain chemical compounds containing phosphorus.
Phosphorus
An essential chemical food element that can contribute to the eutrophication of lakes and other
water bodies. Increased phosphorus levels result from discharge of phosphorus containing
materials into surface waters.
Photochemical smog
Air pollutant formed by the action of sunlight on oxides of nitrogen and hydrocarbons.
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Pollutant
Generally, any substance introduced into the environment that has the potential to adversely
affect the water, soil or air. See Residual.
Pollution
Generally, the presence of matter or energy whose nature, location or quantity produces
undesired environmental effects.
Power
The rate at which energy is converted or transmitted in a given period of time.
Primary energy sources
Any natural energy source available in nature which can be transformed into a useful energy form,
such as coal, solar, biomass.
PVC
A tough, environmentally indestructible plastic (chemical name: polyvinyl chloride) that releases
hydrochloric acid when burned.
Recycling
The process of minimising the generation of waste by recovering useable products that might
otherwise become waste. Examples are the recycling of aluminium cans, waste paper and bottles.
Reserves
The portion of a resource base that is proven to exist and can be economically recovered, that is,
the value of the product exceeds the production and transportation costs.
Residual
A pollutant remaining in the environment after a natural or technological process has taken place,
e.g. the sludge remaining after initial waste-water treatment or particulates remaining in air after
the air passes through a scrubbing or other pollutant removal process.
Resources
The total existing stock of a resource, including discovered and not yet discovered portions,
regardless of the economic feasibility of recovering the resource.
Risk assessment
The qualitative and quantitative evaluation performed in an effort to define the risk posed to
human health and/or the environment by the presence or potential presence and/or use of specific
pollutants.
Rotation period
Age of a tree when it becomes mature for harvest
Rural electrification
The extension of supply of electricity to the rural areas, conventionally by extending the national
grid based on centralised generating power plants but now taken to include small scale
decentralised generating systems.
RWEDP
Regional Wood Energy Development Programme in Asia.
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Scrubber
An air pollution control device that uses a spray of water or reactant or a dry process to trap
pollutants in emissions.
Secondary energy
Energy in a form ready for transport or transmission.
Sink
In air pollution, the receiving area for material removed from the atmosphere, e.g. by virtue of
photosynthesis, plants are sinks for carbon dioxide.
Solar Photovoltaics
Technologies which convert sunshine into electricity using solar cells (photosensitive silicon cells).
Solar Thermal Energy
Energy derived from converting sunshine into direct heating applications, such as water heating,
or to produce electricity in a steam generating plant.
Solvents
Liquids that dissolve other substances. Chemical solvents are used widely in industry. They are
used by pharmaceutical makers to extract active substances; by electronics manufacturers to
wash circuit boards; by paint-makers to aid drying. Most solvents can cause air and water
pollution and can be a health hazard.
Standing stock
Total volume of trees in a specified area.
Sulphur dioxide (SO2)
A colourless, irritating pungent gas formed when sulphur burns in air, one of the main air
pollutants that contribute to acid rain and smog. Comes from the combustion of the sulphur
present in most fossil fuels.
Suspended Particulate Matter (SPM)
Fine liquid or solid particles such as dust, smoke, mist, fumes or smog, found in air or emissions.
Sustainable development
Development that meets present needs without compromising the ability of future generations to
meet their own needs. Necessarily based on limited data due to our current inability to forecast
accurately 50-100 years ahead.
Synergistic
Interaction between two or more forces such that their combined effect is greater than the sum of
their individual effects.
Tradeable permits
Market mechanism for controlling pollution; it entails issuing permits to pollute up to fixed limits
and grants the right to sell unused portions of the permits.
Traditional energy
Forms of energy derived from locally available biomass, animate power and other renewable
energy sources using rudimentary production processes and technologies.
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Tree production rate
Annual increment of standing stock per unit area.
UNCED
United Nations Conference on Environment and Development; it took place at Rio de Janeiro in
June 1992 and was convened by the General Assembly in its resolution 44/228.
UNDP
United Nations Development Programme.
UNEP
United Nations Environment Programme.
Unsatisfied demand
The difference between expressed demand and effective (or satisfied) demand, also called
suppressed demand
Useful energy
Energy which is available to perform the task required by the end-user, such as heat, light or shaft
power.
UV-B
Short wavelength ultraviolet radiation.
Waste
Unwanted materials left over from a manufacturing process and refuse from places of human or
animal habitation.
Waste reduction audit
Highly cost-effective technique that follows material inputs into the production process and
accounts for them quantitatively, in any form (solid, liquid, gaseous), to identify losses (wastes),
which can then be reduced by changes in input materials, process technology, product design and
recycling.
Waste minimisation
The reduction of waste by changing materials, processes or on-site disposals arrangements in a
way that is profitable for the enterprise and the environment. Also called waste reduction.
Water quality standards
Ambient standards for water bodies. The standards address the use of the water body and set
water quality criteria that must be met to protect the designated use or uses.
WCED
World Commission on Environment and Development
WEC
World Energy Council
WICE
World Industry Council for the Environment, a division of the International Chamber of Commerce
that raises environmental awareness on the part of industry in developing and developed
countries.
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Wind farm
A group (or array) of wind turbines connected to a grid for producing electricity.
Woody biomass
Stems, branches, shrubs, hedges, twigs and residues of wood processing.
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