Assessing the sustainability of bioethanol production in Nepal

Assessing the sustainability of bioethanol production in Nepal
TRITA-ECS 2010-01
Dilip Khatiwada
ISBN 978-91-7415-769-7
Assessing the sustainability of bioethanol production in Nepal
KTH 2010
www.kth.se
Assessing the sustainability
of bioethanol production
in Nepal
D i l i p K h at i wa d a
Licentiate Thesis in Energy Technology
Energy and Climate Studies
Stockholm, Sweden 2010
Asseessing th
he sustaainabilitty of
bioeth
hanol producti
p
ion in Nepal
N
Dilip
p Khatiw
wada
Licen
ntiate Thesis 22010
Division of Energy and Clilimate Studiess
D
Technology
Departmentt of Energy T
KTH Sch
hool of Industtrial Engineerring and Man
nagement
STOCK
KHOLM, SW
WEDEN
ISBN 978-91-7415-769-7
TRITA-ECS 2010-01
© Dilip Khatiwada
Abstract
Access to modern energy services derived from renewable sources
is a prerequisite, not only for economic growth, rural development
and sustainable development, but also for energy security and climate change mitigation. The least developed countries (LDCs)
primarily use traditional biomass and have little access to commercial energy sources. They are more vulnerable to problems relating
to energy security, air pollution, and the need for hard-cash currency to import fossil fuels. This thesis evaluates sugarcanemolasses bioethanol, a renewable energy source with the potential
to be used as a transport fuel in Nepal.
Sustainability aspects of molasses-based ethanol have been analyzed. Two important indicators for sustainability, viz. net energy
and greenhouse gas (GHG) balances have been used to assess the
appropriateness of bioethanol in the life cycle assessment (LCA)
framework. This thesis has found that the production of bioethanol is energy-efficient in terms of the fossil fuel inputs required to
produce it. Life cycle greenhouse gas (GHG) emissions from production and combustion are also lower than those of gasoline. The
impacts of important physical and market parameters, such as sugar cane productivity, the use of fertilizers, energy consumption in
different processes, and price have been observed in evaluating the
sustainability aspects of bioethanol production.
The production potential of bioethanol has been assessed. Concerns relating to the fuel vs. food debate, energy security, and air
pollution have also been discussed. The thesis concludes that the
major sustainability indicators for molasses ethanol in Nepal are in
line with the goals of sustainable development. Thus, Nepal could
be a good example for other LDCs when favorable governmental
policy, institutional set-ups, and developmental cooperation from
donor partners are in place to strengthen the development of renewable energy technologies.
Keywords: Bioethanol, sustainability, life cycle assessment, net energy values,
greenhouse gas (GHG) balances, sustainable development, least developed
countries (LDCs), Nepal
I
Preface
This thesis has been developed in the Division of Energy and Climate Studies (ECS), Department of Energy Technology at KTH –
School of Industrial Engineering and Management, within the
framework of the Global Energy and Climate Studies Program,
supported by the Swedish Energy Agency. Research at ECS has an
interdisciplinary character with a strong systems-based approach
dealing with cross-cutting issues of sustainable energy systems, viz.
energy, climate change and sustainable development. Research at
ECS is currently focused on bioenergy systems, rural electrification, and energy and climate policy.
In this thesis, the sustainability paradigm of bioethanol production,
with regard to environmental stewardship, economic prosperity,
and social integrity is dealt with in relation to one of the world’s
least developed countries (LDCs), Nepal. It is important to analyze
the sustainability criteria of the renewable bioenergy systems when
LDCs are living with energy and food poverty and myriad resource
pressures, whilst endeavouring to sustain their livelihoods and
achieve the goals of sustainable development.
This Licentiate thesis has been written as part of an ongoing PhD
program in the assessment of sustainable bioenergy systems at a
regional and global level. The evaluation of bioethanol production
with methodological improvements aimed at finding international
common ground is the next step in the research.
II
Publications
The current licentiate thesis is based on the following publications
which are appended at the end of the thesis:
I.
Paper - I: Khatiwada, D., Silveira S., 2009. Net energy balance
of molasses based ethanol: The case of Nepal. Renewable and
Sustainable Energy Reviews 13, pp. 2515-2524 [Available
online at Elsevier's www.sciencedirect.com]
II. Paper - II: Khatiwada, D., Silveira S., 2010. Greenhouse gas
balances of molasses based ethanol in Nepal (under review,
Journal of Cleaner Production). Revised manuscript of this
paper is appended in the thesis.
III. Paper - III: Silveira, S., Khatiwada, D., 2010. Ethanol production and fuel substitution in Nepal—Opportunity to promote
sustainable development and climate change mitigation. Renewable and Sustainable Energy Reviews 14, pp. 1644-1652
[Available online at Elsevier's www.sciencedirect.com]
III
Acknowledgements
First of all, I would like to express my profound gratitude and sincere appreciation to my thesis supervisor Prof. Dr. Semida Silveira
for inviting me to join her research team at ECS as a PhD student
and for her superb guidance and creative suggestions regarding my
research work. This thesis would have not come together in this
form without her continuous supervision.
I would also like to thank my colleagues Brijesh, Francis, Maria,
Tomas and Henrique at the Division of Energy and Climate Studies (ECS). Furthermore, I extend my special thanks to Mr. Johannes Morfeldt for his generous support and necessary assistance
during this thesis period.
I appreciate the work of Dr. Peter Hagström (KTH) for accepting
to review this thesis, and providing valuable inputs. My sincere
thanks also go to Dr. Andrew Martin, my thesis co-supervisor,
who has provided special assistance and guided me a lot during my
Master’s degree, as the program director.
I would like to thank the Swedish Energy Agency for providing
partial funding, as a part of the Global Energy and Climate Studies
Program, to allow me to complete my licentiate thesis.
Last but not least, I thank my wife, Ruchita and my beloved son,
Shreyash for their endurance, love, encouragement and moral support even from a great distance, in my home country – Nepal.
IV
Abbreviations and Nomenclature
ADP
BEFS
CDM
CH4
CHP
CO2
CO2eq
COD
E10
E20
E5
Ef
Ei
ESCAP
EtOH
ETP
EU
FAO
GHG
GJ
GoN
Ha
HC
HHV
IAEA
IEA
IPCC
ISO
K2O
Kcal
kg
kgCO2eq
KJ/kg
KL
koe
ktoe
kW
Anaerobic Digestion Process
Bioenergy and Food Security
Cleaner Development Mechanism
Methane
Combined Heat and Power
Carbon Dioxide
Carbon Dioxide Equivalent
Chemical Oxygen Demand
10% ethanol and 90 % gasoline (v/v)
20% ethanol and 80% gasoline (v/v)
5% ethanol and 95 % gasoline (v/v)
Lower Heating Value of Fuel ethanol
Primary Energy Inputs
The United Nations Economic and Social
Commission for Asia and the Pacific
Ethanol (>99.5% v/v), E100 or MOE
Effluent Treatment Plant
European Union
United Nations Food and Agricultural Organization
Greenhouse Gas
Giga Joule
Government of Nepal
Hectare, also ha
Hydro-Carbon
Higher Heating Value
International Atomic Energy Agency
International Energy Agency
Intergovernmental Panel on Climate
Change
International Standards for Organization
Potash
Kilocalorie
Kilogram
kg Carbon Dioxide Equivalent
Kilo Joule per Kilogram
Kilo-liter
Kilogram of Oil Equivalent
Kilo-tonnes of Oil Equivalent
Kilowatt
V
kWh
L
LCA
LDCs
LHV
LPG
m-3
m3
MDGs
MJ
MJL-1
MJ-1
MOE
MW
N
N2O
NEB
NEi
NEV
Nm3
NOC
NREV
NRs
OECD
ON
P2O5
PS
SRSM
Tonne
TPES
UNDP
UNFCCC
US
USD ($)
v/v
w/w
WECS
Kilowatt-hour
Liter
Life Cycle Assessment
Least Developed Countries
Lower Heating Value
Liquefied Natural Gas
Per Cubic Meter
Cubic Meter
Millennium Development Goals
Mega-joule
Mega-joule per Liter
Per Mega-joule
Molasses Based Ethanol or EtOH
Mega Watt
Nitrogen
Nitrous Oxide
Net Energy Balance or NEV
Non-Renewable or Fossil Fuel Inputs
Net Energy Value or NEB
Normal Cubic Meter
Nepal Oil Corporation
Net Renewable Energy Value or Balance
Nepalese Currency Rupees
Organisation for Economic Co-operation
and Development
Octane Number
Phosphorous
Pond Stabilization or Lagoon System
Sri Ram Sugar Mills Pvt. Ltd.
1000 kilogram (kg)
Total Primary Energy Supply
United Nations Development Program
United Nations Framework Convention on
Climate Change
United States of America
US Dollar
Volume by Volume
Weight by Weight
Water and Energy Commission Secretariat
VI
Table of Contents
ABSTRACT
I
PREFACE
II
TABLE OF CONTENTS
VII
INDEX OF FIGURES
INDEX OF TABLES
1
1.1
1.2
1.3
1.4
1.5
VIII
IX
INTRODUCTION
1
BACKGROUND
THESIS OBJECTIVE
RESEARCH QUESTIONS AND HYPOTHESES
SCOPE AND LIMITATIONS
ORGANIZATION OF THE STUDY
1
5
5
6
7
2
STATE-OF-ART TECHNOLOGIES IN BIOETHANOL
PRODUCTION AND UTILIZATION
9
2.1
2.2
2.3
BIOFUELS – AN OVERVIEW
BIOETHANOL PRODUCTION
BIOETHANOL AS A TRANSPORT FUEL
3
SUSTAINABILITY CRITERIA AND LIFE CYCLE
ASSESSMENT – CONCEPTS AND FRAMEWORKS
3.1
3.2
3.3
3.4
3.5
3.5.1
3.5.2
3.5.3
4
4.2.1
4.3
4.3.1
4.3.2
16
OVERVIEW
16
DEFINING SUSTAINABLE DEVELOPMENT AND SUSTAINABILITY 16
DEFINING LIFE CYCLE ASSESSMENT (LCA)
20
INTEGRATING SUSTAINABILITY AND LCA
21
DEVELOPMENT OF SUSTAINABILITY CRITERIA FOR BIOETHANOL
23
PRODUCTION
Identification of sustainability indicators for bioethanol in
Nepal
24
Defining net energy and greenhouse gas (GHG) balances 26
Realization of a case study – sensitivity analysis and
development of scenarios
28
RESULTS AND DISCUSSIONS
4.1
4.2
9
12
14
34
OVERVIEW
34
LIFE CYCLE NET ENERGY BALANCES AND TOTAL ENERGY YIELD
34
RATIO
Sensitivity analysis (net energy balances)
37
LIFE CYCLE GHG BALANCES AND AVOIDED EMISSIONS
39
Sensitivity analysis (GHG balances)
42
Alternative scenarios and system expansion
44
VII
4.4
4.5
4.5.1
4.5.2
4.5.3
4.5.4
4.6
5
5.1
5.2
6
COMPARISON OF RESULTS WITH OTHER STUDIES
48
PROSPECTS FOR SUSTAINABLE DEVELOPMENT
50
Ethanol production potential in Nepal
50
Substituting gasoline with E10 and E20 in the Kathmandu
Valley
50
Environmental gains of introducing E10 and E20 in the
Kathmandu Valley
51
Other important aspects of sustainable development
52
RESULTS OF SUSTAINABILITY ASSESSMENT: A SUMMARY SHEET
54
CONCLUSIONS AND FUTURE WORK
56
CONCLUSIONS
FUTURE WORKS
56
59
REFERENCES
60
Index of Figures
Figure 1:
Simplified layout of sugarcane bioenergy systems in
Nepal
7
Figure 2:
Layout of the thesis
Figure 3:
The production of biofuels from different biomass sources
10
Figure 4:
Production routes of bioethanol
Figure 5:
The three pillars of sustainability and their interaction in the
sustainable energy system
18
Figure 6:
Integration of LCA and sustainability assessment
Figure 7:
System boundary and material flows (per hectare) for
sugarcane-based systems in Nepal
31
Figure 8:
Realization of the case study in Nepal: sugarcane farming
and factory operations
33
Figure 9:
The contribution of fossil and renewable energy required to
produce 1 liter of EtOH (MOE) in Nepal, at each stage of
the ethanol production chain
37
Figure 10:
Effect of changes in the price of molasses on NEV,
NREV, and the energy yield ratio
38
8
VIII
13
22
Figure 11:
Effect of different levels of energy consumption at the
ethanol plant on NEV values
39
Figure 12 :
Sensitivity analysis for life cycle GHG emissions and
avoided emissions (%) as a function of different allocation
ratios for sugar and molasses
42
Figure 13:
Sensitivity analysis for variations in material/energy inputs
and sugarcane yield in Nepal
43
Figure 14:
Life cycle emissions in the case of partial treatment of
wastewater in PS and ADP
45
Figure 15:
Life cycle emissions in the case of biogas leakage
Figure 16:
GHG emissions shares from different stages of the ethanol
production chain in Nepal (in the case of using surplus
electricity to substitute diesel)
47
46
Index of tables
Table 1:
Selected sustainability criteria for evaluating the
appropriateness of bioethanol production and use in
transport – the case of Nepal
25
Table 2:
Primary energy requirement of one hectare of sugarcane
farmland in Nepal (40.61 tonne/ha)
35
Table 3:
Primary energy balance of sugar milling in Nepal (including
distillation, dehydration and ETP)
36
Table 4:
GHG emissions from sugarcane farm land per hectare in
Nepal (sugarcane yield: 40.61 tonne/ha)
40
Table 5:
Life cycle GHG (CO2eq) balance of molasses-based ethanol
(MOE, EtOH) fuel in Nepal
41
Table 6:
Life cycle comparison of GHG emissions, ethanol (EtOH)
and gasoline
41
Table 7:
Evaluating selected sustainability criteria for bioethanol
production and use in Nepal – Summary of thesis results 55
IX
1 Introduction
1.1
Background
The continuous depletion of limited fossil fuel reserves, the global
agenda on climate change and threats to energy security have led
to increased global interest in the exploration, production and utilization of biofuels in the transport sector. Bioenergy systems have
been drawn to the attention of policy makers since they reduce dependence on fossil fuel, contribute to rural and sustainable development, and are carbon-neutral. Reasons to promote biofuels include energy security, environmental concerns, foreign exchange
savings and socio-economic well-being of rural dwellers
(Demirbas, 2008). Rising oil prices and energy security issues are
the source of serious concerns in developing and least developed
countries (LDCs) while climate change has led to the development
of a global agenda that is also promoting renewable energy
(UNIDO, 2006).
Modern liquid biofuels are seen as promising transport fuels in relation to reducing environmental impacts and improving energy
security. Today, the transport sector consumes about 30% of the
world’s total primary energy consumption and is one of the major
contributors to global greenhouse gas (GHG) emissions. Increased
use of fossil-fuel-based motorized transportation in urban areas of
developing countries has not only exacerbated problems of local
air pollution, but also poses energy security threats and high economic costs (Creutzig and He, 2009; Yan and Crookes, 2010).
Least developed countries (LDCs), which basically depend on traditional forms of energy (e.g. biomass) and have little access to
commercial energy sources (e.g. electricity and liquid fuels) for
their economic activities, are particularly vulnerable to issues surrounding energy security, air pollution, and the sustainability of
their development. In addition, they cannot afford the cost of importing fossils fuels.
The least developed countries (LDCs) are characterized by lowincome, weak human resources/assets, and high economic vulnerability. Their populations suffer severe distress in the face of rising
1
food and energy prices (UNCTAD, 2009). To achieve the Millennium Development Goals (MDGs), proper energy services need to
be guaranteed for the poor (UNMCLDC, 2007). Indeed, access to
modern energy services, sustainability (e.g. deforestation, land use,
natural environment, and GHG emissions) and energy security are
three areas that LDCs need to address to reach the MDGs (UNMCLDC, 2007).
Traditional fuel consumption contributes 78.3% of the total energy
in LDCs, while the figures for developing and OECD countries
are 26.3% and 4.6% respectively (UNDP, 2006). Commercial energy (coal, oil, and electricity) consumption in LDCs was only 67
koe (kg of oil equivalent) per capita in 2004 while other developing
countries consumed 718 koe (UNCTAD, 2008). In Asia and the
Pacific (ESCAP), half of the countries, including LDCs, landlocked developing countries and small island developing states are
categorized as being more vulnerable with regard to energy security and sustainable development. The total final energy consumption of the least developed countries (LDCs) is only 47.02 thousand ktoe, compared to a total of 2,992 thousand ktoe in the ESCAP, whilst the contribution of liquid fuels in LDCs is only 6.1
thousand, out of a total of 912 thousand ktoe in the region (UNESCAP, 2008). Moreover, LDCs have few resources for financing
infrastructure. The average value of domestic resources available
for financing governance and investment was only 41 cents per
capita in LDCs compared to $3.2 and $36.4 in lower-middle and
high-income countries respectively (UNCTAD, 2009).
However, there is huge potential for developing modern bioenergy
in LDCs. According to Batidzirai et al., (2006), there is a large bioenergy potential in Mozambique that can be harnessed without
compromising food demand and creating deforestation. FAO
(2010) evaluated suitable pathways for developing biofuel production in conjunction with food security and poverty reduction as a
way of realizing the enormous potential of biofuels in Tanzania. In
African LDCs, average commercial energy consumption per capita
was only 30.4 koe compared to 313 koe (kg of oil equivalent) in
Africa as a whole (UNIDO, 2008). Thus, LDCs lack a basic supply
of modern energy services and the financial resources to invest in
them. Although they still only constitute a limited market for
commercial liquid fuels for transportation, and are the lowest emit-
2
ters of GHGs, LDCs are highly vulnerable to global warming and
its related consequences (Huq et al., 2003).
Bioethanol has been used in the transport sector as a substitute for
conventional gasoline. Bioethanol helps to reduce the use of fossil
fuels, and to mitigate against climate change, while also promoting
the socio-economic transformation of developing societies. Bioethanol already contributes 90% of the total biofuel market in the
world, and its production could be significantly increased, particularly in sugar producing countries, where it can be used to replace
fossil fuels (Balat et al., 2008; Balat and Balat, 2009). However, the
production of biofuels has been debated in the context of environmental performance, food versus energy security and land use,
among others.
Nepal, a least developed and landlocked country in South Asia,
does not have fossil fuel reserves. Nepal’s total primary energy
supply (TPES) system is dominated by the use of traditional biomass (87.71%), followed by fossil fuels (9.94%), hydroelectricity
(1.82%), and renewable sources 0.53% (WECS, 2006). The
transport sector is the largest consumer of petroleum products.
Kathmandu Valley, the capital city alone, consumes about 70% of
the total imported gasoline. This area is also the place where 56%
of the total number of vehicles run. Vehicular emissions are a major source of air pollution in the Valley, and its bowl-shaped topography tends to exacerbate local pollution problems. The accumulation of foreign debts for oil imports, at a rising cost, the frequent shortage of transport fuels, public unrest due to rises in the
subsidized price of petroleum products, and alarming air pollution
have contributed to the initiation of discussions about alternative
sources of transport fuel in the Kathmandu Valley. Increasing foreign debts have also put pressure on the national economy as they
divert money away from the scarce developmental budget of the
country.
As a result, the Government of Nepal (GoN) decided to blend
10% ethanol with gasoline (in 2004), and formed a high level
committee with the task of finding energy alternatives to reduce oil
consumption (in 2008). One of the sugarcane factories, Sri Ram
Sugar Mills Pvt. Ltd. (SRSM) has also constructed an ethanol plant
in Nepal. However, the potential of ethanol production has not yet
3
been realized due to conflicting economic, technical and political
issues, and a lack of promising trust amongst major stakeholders.
Least developed countries (LDCs) have not yet harnessed their
huge potential in producing ethanol from sugarcane systems.
However, in recent times, they have been showing interest in the
development and deployment of sugarcane bioenergy in an effort
to reduce dependence on imported fuels and enhance domestic
energy security, as is the case with Nepal. Both private and public
sectors are willing to promote this commercial biofuel. International cooperation on the climate change agenda could also help to
initiate work in sustainable sugarcane bioenergy systems in LDCs,
such as the Bioenergy and Food Security (BEFS) program in Tanzania (FAO, 2010). Versteeg (2007) has evaluated the environmental sustainability of sugarcane-bioethanol production in Fiji, a small
island developing state in the Pacific, estimating reductions in life
cycle GHG emissions, net energy balances, and ecological footprints in the context of sustainable development. The feasibility
study focused on how to select LDCs to produce bioethanol in an
effective and sustainable way, indicating that surplus cane sugar,
dependency on imported fuels, and economic production potential
are the key selection criteria (DSDG, 2005). UNDESA (2007) has
also discussed the technical, socio-economic, and environmental
benefits of small scale biofuel production as a means of promoting
sustainable development in sub-Saharan Africa, focusing on the
poor’s access to energy, the reduction of oil imports, income generation, rural development and the improvement of local environmental pollution. However, detailed analyses of the production of
bioethanol have not been carried out for LDCs in general, and
Nepal in particular. This study aims to make a contribution towards this, with an analysis of the case of Nepal using the life cycle
perspective.
This thesis uses three pillars of sustainable development to analyse
sugarcane-molasses based bioethanol (MOE) production in Nepal.
Sustainability criteria and life cycle assessment (LCA) provide the
methodological framework for the study. It is the first of its kind
in LDCs and assesses the sustainability criteria of bioethanol in the
case of Nepal. The study provides useful information for decision
makers, private investors, and other associated stakeholders, interested in developing ethanol production in Nepal. The example of
4
Nepal also serves the purpose of motivating the assessment of
ethanol production potential in other LDCs.
1.2
Thesis objective
The main objective of this thesis is to investigate the net energy
balance, GHG emissions of bioethanol from a life cycle perspective, and prospects for sustainable development in Nepal. The objective has been achieved in the following steps:
1.
2.
3.
Estimation of the net energy balance in the production
of sugarcane-molasses-based bioethanol (MOE)
Examination of greenhouse gas (GHG) balances in
the production and use of bioethanol
Evaluation of bioethanol production for the purposes
of sustainable development
1.3 Research questions and hypotheses
The following research questions have been asked in the thesis:
) Is bioethanol energy efficient; how much energy does
it take to produce one liter of bioethanol?
) How many greenhouse gas (GHG) emissions and savings occur in the production and use of bioethanol?
) What are the direct benefits of bioethanol substitution
in the transport sector?
The first and second questions are life cycle assessment (LCA) related questions, and the third is concerned with the immediate
benefits, and sustainability issues observed from the production
and use of bioethanol in the transport sector. Addressing these
questions, this study performs a sustainability assessment of the
production and use of bioethanol in Nepal. The answers to these
questions provide valuable insights into the production of molasses-based ethanol in the least developed countries (LDCs) with respect to energy security, climate change mitigation, and sustainable
development.
As per the research questions above, and based on reviews of previous literature on bioethanol conversion technologies, life cycle
5
assessment and aspects of sustainability, the following hypotheses
have been tested:
9 The production of bioethanol requires a small amount of
fossil fuel compared to its energy content.
9 Life cycle greenhouse gas (GHG) emissions from bioethanol are lower than conventional gasoline.
9 Bioethanol contributes to improved socio-economic and
environmental performance, and can be promoted in Nepal in order to achieve sustainable development.
1.4 Scope and limitations
This thesis considers the full energy life cycle, material/waste
flows, and carbon (GHG) flows involved in producing anhydrous
ethanol (EtOH) from sugarcane molasses in Nepal. The system
boundary covers local agricultural practices, the harvesting of sugarcane, cane milling, the ethanol conversion phase, through the
fermentation, distillation and dehydration route, and waste management. Figure 1 provides a simplified schematic diagram of the
sugarcane energy system in Nepal. Data sources relating to material, energy, and waste flows have been taken from an intensive field
study visit made to one of the established sugar factories in Nepal
– Sri Ram Sugar Mills Pvt. Ltd. (SRSM). SRSM is the only factory
which has installed a molasses-based ethanol conversion unit, and
associated ancillaries such as wastewater treatment plants with biogas recovery. It is assumed that the factory operations for molasses-based ethanol conversion at SRSM are the best available in
Nepal. Energy and greenhouse gas (GHG) balances have been estimated from local inventory data for material and energy flows.
The corresponding energy values and emission factors have been
derived from regional and international studies.
Solar energy inputs have not been considered in the analysis of the
net energy balance. Energy inputs and GHG emissions from human labour have been considered. Energy generation and GHG
emissions avoided by the commercial utilization of cane trash /
waste have not been taken into account. In addition, energy inputs
and corresponding GHG emissions for raw materials (for industrial installations), and oil/lubricants/chemicals (for factory operations) have also been excluded from this thesis. Sensitivity analyses
have been performed to scrutinize the impacts of the variation in
6
material and eneergy flows, and scenarioos have beeen developed to
f
expan
nsion of moolasses-based
d ethanol pllants
incorrporate the future
in othher sugar/diistillery indu
ustries in Neepal.
Figurre 1: Simpllified layoutt of sugarccane bioeneergy system
ms in
Nepal
The iintended auudience of th
his thesis arre policy maakers, privatee investoors, research
hers, and oth
her stakehoolders (e.g. donor
d
agenccies),
who are interesteed and motiivated enouggh to consid
der making concerted efforts to
owards the production
p
oof commerccial bioenerggy in
the fo
form of bioeethanol in th
he least deveeloped counttries (LDCs)).
1.5
Organization of the study
This thesis is divvided into fivve chapters. The layout and flow off the
thesiss is presenteed in Figuree 2. Chapterr 1 deals wiith the ratio
onale
and oobjectives of the study. In Chapterr 2, an overvview of statee-ofthe-aart technolo
ogies in biofuel producction, and bioethanol
b
as a
transport fuel, arre presented
d. Methodollogical concepts and fraameworkks, with regaard to sustaiinability asseessment critteria and lifee cycle asssessment (L
LCA) are exxplained in Chapter 3. Reviews
R
of previouss research liiterature reggarding LCA
A, and the sustainability
s
y aspectss of biofuel production
p
have also beeen carried out.
o
Chappter 4 is the main bodyy of the thessis which beegins with a discussion of the firrst paper on
n ‘net energyy balances’. The major findf
ings oof the paperr concerningg life cycle ‘ggreenhouse gas (GHG) bal7
ancess’ are also discussed.
d
Su
ustainability aspects of bioethanol productiion and the findings of the paper ‘E
Ethanol prod
duction and fuel
substtitution in Nepal
N
- Opp
portunity to promote suustainable deevelopmeent and clim
mate change mitigation’ are explain
ned, which elucidatess the generall prospects for sustainab
ability in bioethanol production iin Nepal. Fiinally, the reesults are preesented and
d compared with
thosee from a sm
mall number of internatioonal studies. Chapter 5 presentss concludingg remarks an
nd indicatess the next steps in research
towards a PhD.
Figurre 2: Layoutt of the thesiis
8
2 State-of-ar t technologies
in bioethanol production
and utilization
2.1
Biofuels – an overview
Bioenergy is obtained from biomass, in the form of different solid,
liquid or gaseous fuels. Food crops (sugarcane, corn, soybean,
wheat, and sugar beet), hydrocarbon-rich plants, wastes (crop,
food, and municipal), weeds and wild growths, and lignocellulosic
biomass are the potential sources of biomass for bioenergy generation (Abbasi and Abbasi, 2010). Biodiesel is obtained through the
esterification of plant oils, whereas bioethanol is mainly derived
from agricultural feedstocks. The use of biofuels in the transport
and industrial sectors tends to be on the increase due to growing
concerns about fossil-fuel reserves, climate change and sustainable
development. Liquid biofuels, namely biodiesel and bioethanol,
are used in their pure or blended form (with conventional gasoline
or diesel) in automobiles.
Biofuels from biomass are obtained primarily through two production processes: bio-chemical and thermo-chemical; bio-chemical
processes may be further broken down into chemical and biological conversion technologies (Abbasi and Abbasi, 2010; Sheehan,
2009; Walter and Ensinas, 2010). With the thermo-chemical route,
biomass is heated in the absence (or regulated/controlled concentration) of oxygen, which includes pyrolysis, gasification, and Fisher-Tropsch processes. The Bio-chemical route consists of five alternatives - fermentation, esterification, anaerobic digestion, photosynthetic organisms, and dark fermentation (Abbasi and Abbasi,
2010). Fermentation and esterification produce bioethanol and biodiesel respectively whilst anaerobic digestion creates biogas. Photosynthetic organisms and dark fermentation are part of the experimental phase.
Fermentation and anaerobic digestion are classified as biological
processes, whereas trans-esterification and hydro-treating follow
chemical processes, in terms of bioenergy conversion technologies,
9
as shhown in Figuure 3. The advantage
a
o f the thermo-chemical process iis that it con
nverts almost all of the organic com
mponents off the
biom
mass into bio
oenergy, wh
hereas bio-chhemical pro
ocesses onlyy utilise tthe polysacccharide con
ntent of thee biomass. Operation and
mainntenance cossts are quitee high in thhe thermo-ch
hemical con
nversion, and these processes
p
usually consuume significcant amountts of
Abbasi and Abbasi,
A
2010
0).
fossill fuel along the producttion chain (A
Figurre 3: The pro
oduction off biofuels froom differentt biomass
sourcess
(Includes first, second and third genneration biofueels)
Adoptedd from Sheehan (2009)
Biofuuels are broaadly divided
d into severaal categoriess, dependingg upon ffeedstock characteristiccs and pro duction pathways. Sev
veral
studiies provide reviews off biofuels ttechnologies used glob
bally
A, 2005; Royyal Society, 2008;
2
Nigam
m and Singh
h, 2010; Yan and
(IEA
Lin, 2009; Naik et al., 2010)). First geneeration biofuuel technolo
ogies
are w
well established, and in
nclude the ffermentation
n of sugars and
starchhes and the trans-esterification of pplant oils. For
F examplee, cereals,, grains and sugar cropss can be ferm
mented to produce
p
bioeethanol, while oilseeed crops su
uch as sunfflower, rapee-seed, soyb
bean,
m and jatrop
pha can be converted
c
too methyl essters (biodieesel).
palm
How
wever, first generation
g
biofuels
b
are being debatted due to con10
cerns over land use, food security/prices, water scarcity, and deforestation. Second generation biofuel conversion technologies are
complex, expensive and at an early stage of research & development and commercialization. They are obtained from, among other things, lignocellulose (cellulose, hemicelluloses, and lignin – e.g.
woodchips, straw and, cane bagasse) and feedstocks, through a
conversion route which includes acid hydrolysis, followed by enzymatic fermentation.
Second generation biofuels, produced from agricultural and forestry residues, municipal solid waste, and other forms of lignocellulosic biomass, can improve energy security, and reduce urban air pollution (Wyman, 1994) in spite of increased concerns about changes
in land use patterns (Brennan and Ownede, 2010). Third generation biofuels, derived from microalgae, could avoid land use
changes since they can be grown in aquatic media i.e. watersurfaces (Brennan and Ownede, 2010; Goh and Lee, 2010). New
research has been initiated in the development of genetically modified crops/plants, and novel biofuels from non-food oil crops.
At present, commercial biofuels are mainly derived from energy
crops (e.g. sugarcane, corn) and oil feedstocks (e.g. palm oil,
oilseed rape). The production of biofuels has increased significantly in the past decade (GRFA, 2009). The reduction of greenhouse
gas (GHG) emissions, achieving CO2 targets, the diversification
away from commercial energy systems, favourable government
policy and rural development are a few motivating factors in terms
of encouraging biofuel production. Furthermore, biofuels can help
to ensure energy security, reduce the environmental impacts arising
from the transport sector, and create a conducive environment for
economic growth in rural areas and the industrial sector at large.
Nigam and Singh (2010) have highlighted energy security, economic stability and environmental gains as the main advantages of using biofuels. The key drivers of biofuel development in Asia are:
(a) the security of the energy supply chain, (b) climate change, (c)
land use changes and food security, and (d) rural development and
poverty alleviation (Yan and Lin, 2009). Zhou and Thomson
(2009) have also mentioned energy security, trade balances, foreign
exchange, reduction in government expenditure, new markets for
the principal agricultural products, employment in the agricultural
sector, and climate change as being the driving forces, while deforestation, problems with water security, the sdanger of monocul11
ture, biofuels and food prices are highlighted as some of the negative impacts of biofuels production in Asia. Escobar et al., (2009)
have assessed issues relating to environment, technology and the
food security of biofuels. Debates surrounding the production of
biofuel using the same raw materials for both fuel and food production, and changing land use patterns have encouraged the assessment of the sustainability of biofuels.
2.2
Bioethanol production
Bioethanol contributes more than 90% of the total liquid biofuel
consumption in the world (IEA, 2007). Figure 4 shows different
routes for the bioethanol production process. As can be seen in
the figure, sugar/starch obtained from sugarcane/corn or cellulose
feedstocks follows the process of fermentation, distillation, and
dehydration in order to produce first and second generation ethanol respectively. It should be noted that molasses (also a sugarbased product) is treated separately in the figure in order to make
it distinct from other conversion routes. This thesis covers molasses-based bioethanol. First generation bioethanol, obtained from
sugarcane and corn feedstocks has so far dominated the bioethanol market globally and other technologies are at an early stage of
development. In 2009, global ethanol production was about 74
billion liters, a four-fold increase since 2000 and it has contributed
to a reduction in GHG emissions by 87.6 million tonnes in a year
(RFA, 2010). The United States (US) was the world largest producer of bioethanol, accounting for about 52% (i.e. 38.5 billion liters) of the total bioethanol production in 2009. Brazil was the
largest bioethanol exporter and second largest producer with a
share of 34% (25 billion liters). The EU produced 3.9 billion liters
(5.3%) whereas two emerging developing countries, China and India, contributed 2.8% and 0.5% of the total bioethanol production
respectively. Bioethanol production could surpass 125 million liters
by 2020 with the development of new agricultural policies/programs along with the exploration of new feedstocks in
America, Asia and Europe (Balat and Balat, 2009). The primary
feedstocks for bioethanol production are corn (US), sugarcane
(Brazil, Thailand, India, Australia), and beet/grain (EU). Different
bioethanol production processes are discussed by various authors
in the literature (Kumar et al., 2010, Abbasi and Abbasi, 2010;
Najafi et al., 2009; Nigam and Singh, 2010; Cardona and Sanchez,
12
2007; IEA, 20055). Ethanol from sugarrcane has prroven to bee the
w decades, fo
ollowing a steep
s
mostt cost competitive over the last few
learnning curve in
n the produ
uction of etthanol (Golldemberg ett al.,
20044; Bake et al., 2009), and
d there is a sttrong globall ethanol maarket
nt (Hira, 20 10).
for innternational developmen
Figurre 4: Producction routes of bioethannol
Adoptedd from Penninggton (2009) wiith the inclusio
on of sugarcane by-products (molasses and baggasse, which is
i also cited
by Abbassi and Abbasi (2010)
Besiddes producin
ng bioethan
nol from suugarcane juicce, as in Brrazil,
otherr developingg countries such as Thhailand and
d India are also
produucing bioeth
hanol using the by-prodduct of the sugar indusstry–
molaasses. Few studies
s
havee been condducted into molasses-based
bioetthanol (Nguuyen and Gheewala,
G
22008a, b, c;; Harijan ett al.,
2009; Prakash ett al., 1998; Kumar
K
et all., 2010; Khatiwada and
d Silveira, 2009). Mollasses (with a fermentabble sugar con
ntent of 40 – 45
% byy weight, w//w) is the byy-product obbtained duriing the crystallization and centrrifugation prrocess in thhe productio
on of sugar at a
pointt when the extraction
e
of
o sugar is noo longer possible. It is considered to be thee cheapest source
s
of biioethanol prroduction (H
Harijan et al., 2009). Pakistan co
ould producee 500 millio
on liters bioeetha13
nol from molasses which could be used in the transport sector in a
blending ratio of 5 – 10%, saving US $ 200 – 400 million per year,
bringing various environmental and health benefits (Harijan et al.,
2009). Mozambique could extract 68 million liters of bioethanol
from sugarcane by 2010 (Batidzirai et al., 2006). Nepal also has a
sugar-molasses bioethanol production potential of 18 million liters
per year (Silveira and Khatiwada, 2010). India could produce an
abundant amount of bioethanol from its available molasses (Kumar et al., 2010). However, policy needs to be focussed on the development and use of bioethanol in order to realise such potential
(Pohit et al., 2009).
In recent years, there have been a number of concerns with regard
to the environmental, social and economic sustainability of bioethanol production. This thesis deals with the sustainability aspects of
molasses-based bioethanol in the case of a sugar-producing least
developed country, Nepal. Chapter 3 provides more details about
the sustainability issues related to bioethanol production.
2.3
Bioethanol as a transport fuel
Bioethanol is the most commonly used liquid biofuel in the transportation sector, especially in Brazil and the US, and its global use
is growing quickly due to increased interest in both developed and
developing countries. Pharmaceutical, cosmetic and beverage items
are also obtained from the use of bioethanol. Thus bioethanol is
not limited to the transport sector (EUBIA, 2005). However, the
largest share of bioethanol (more than 80%) has been used to fuel
automobiles and it is expected to represent a 4% share of the
world’s motor gasoline consumption in 2010 and 6% in 2020
(IEA, 2005).
Vehicles can be fuelled either by pure or neat hydrous bioethanol
(i.e. 95% ethanol v/v) or by a blend of gasoline and anhydrous (i.e.
99.5% v/v) ethanol – the most common blend ranges from 5 –
25% (Costa et al., 2010). It has been found that bioethanol as a
fuel additive improves engine performance and reduces exhaust
emissions in addition to increasing braking power and thermal and
volumetric efficiency (Al-Hasan, 2003). Niven (2005) has examined five important environment impacts of the ethanol enrichment of unleaded gasoline, viz. air pollution, subsurface contami14
nations, greenhouse emissions, energy efficiency, and sustainability. Automobiles with 5 – 10 % ethanol blended fuels do not require any engine adjustments or modifications while minor modifications are needed for a 10 – 25 % ethanol blend (IEA, 2005).
Rising international oil prices, limited fossil-fuel reserves, environmental and climate change concerns, energy security, and diversity of energy sources are the major driving forces behind the
desire for developed countries to produce biofuels. Biofuels may
also help to save foreign currency, improve access to commercial
energy, and generate local employment. However, the biofuel
agenda has not yet had any major impacts in the least developed
countries (LDCs). One important reason is that development donors have not prioritized bioethanol production. In addition,
proper government policies are still lacking, even though the potential for bioethanol production is high.
At the same time, there is increased apprehension about energy security and climate change in both developing and developed countries. Biofuels could contribute towards the mitigation of greenhouse gas emissions while also promoting development. Energy
security concerns and climate threats for the least developed and
land-locked countries are extremely high since they are too weak
economically to invest in new domestic technologies, require agricultural land for a growing population, in order to produce food,
and cannot afford imported fossil fuels. This study is an attempt to
assess the sustainability of bioethanol in the case of a land-locked,
least developed country, Nepal. The study not only highlights the
potential which exists, but also the opportunities to enhance the
potential further and actually contribute to addressing a large
number of national and global questions simultaneously.
15
3 Sustainability criteria and
life cycle assessment –
c o n c e p t s a n d f r a m e wo r k s
3.1
Overview
In this chapter, the concept of sustainable development, sustainability criteria, and life cycle assessment (LCA) are defined. Sustainability aspects of biofuels are presented and relevant criteria are
developed for assessing bioethanol production, based on literature
reviews, and existing local conditions. Issues related to the integration of sustainability and LCA are also discussed. The life cycle assessment (LCA) tool is used to address the sustainable development of biofuels. Indeed, a life cycle based system approach serves
an important role in addressing the economic, social and environmental integrity of any production system.
This thesis uses a LCA methodology to evaluate the net energy
and greenhouse gas (GHG) balances of molasses-based bioethanol
(MOE) from cradle to grave. The case of Nepal, in terms of the
production of bioethanol from sugarcane-molasses is realized and
explained. Other general aspects of sustainability, such as the
economy, local air pollution, and hard currency savings are also
dealt with.
3.2
Defining sustainable
development and
sustainability
In general terms, sustainability covers the realms of environment
(planet), society (people), and economy (prosperity). By sustainable
development, we actually mean that the environment, comprising
the earth and its ecosystems, biodiversity, scarce resources and cultures, needs to be sustained, while people (survival, life expectancy,
education, equity and equality), economy (wealth distribution, consumption), and society (institutions, social capital, states, regions)
need to be developed (Kates et al., 2005)
16
The concept of sustainable development and its underlying three
pillars of sustainability have become important in dealing with the
prosperity of developing and least developed countries (LDCs). In
finding indicators for sustainable energy systems, the current state,
economic and social systems, driving forces, and the responses of
the institutional set up should be dealt with, and their interconnection considered, in order to determine the current situation regarding the sustainability of the energy system as shown in Figure 5.
Economic prosperity, social development and environmental integrity are well connected and involve trade-offs between their
varying objectives. Thus it is very difficult to deal with these factors in isolation. The three pillars always reinforce each other (Hediger, 2000). For instance, environmental pollution always involves
economic costs/activities. Poverty, equality and social justice are
also intertwined. Moreover, institutional strengthening i.e. networking, collaboration and cooperation between stakeholders, and
political stability are also vital in order to enable sustainable development in developing and least developed countries (LDCs). Sustainable development aims to keep the integrity of the overall system. Economic sustainability includes investment, benefits and the
availability and mobility of scarce national resources. Environmental sustainability is the ability of the natural environment to sustain
human life. Social sustainability covers issues of equity and justice
in wealth distribution, for example job creation, and human rights.
Likewise, sustainable development of the bioenergy (biofuels) system is also very significant in terms of creating economic prosperity, and putting in place social and environmental safeguards.
Energy security, rural development, and the climate change agenda
motivate the production and utilization of biofuels derived from
energy crops. Sustainability criteria are needed to justify the appropriateness of these energy systems. Interaction between the three
pillars of sustainable development are crucial, as well as being
complex and multidimensional throughout the production chain,
which includes types of feedstock, land use, conversion technologies, material and energy flows, pollution, and geographical conditions.
17
Figurre 5: The th
hree pillars of
o sustainabiility and theeir interaction in the sustainaable energy ssystem
Adopted from IAEA,, Fact Sheets
Therre is a vast amount of literature oon the sustaainability asssesss
in general and tthe bioenerggy system in parmentt of energy systems
ticulaar (Afgan et al., 2000; Cramer,
C
20066; Elghali ett al., 2007). Four
F
sustaainability inddicators, vizz. resource (e.g. fossil fuel and en
nergy
consuumption), environment
e
t (e.g. emisssions and pollution),
p
so
ocial
(e.g. jobs), and economic (ee.g. investm
ment, cost) are
a used forr as000).
sessinng the sustaainability off energy sysstems (Afgaan et al., 20
Zhouu and Thom
mson (2009) have foundd that energgy security, economiics (trade baalance, pricee of petroleuum, an improved economy),
sociaal dimension
ns (increaseed jobs in tthe agricultuural sector, improveement in faarmers’ inco
ome), and eenvironmenttal impacts (climate change andd air quality) are the maiin driving fo
orces behind
d the
a bioethannol in Asia. Cramer (2006)
devellopment off biodiesel and
has pproposed sixx criteria on the theme oof sustainabiility for biom
mass
produuction, viz. greenhousee gas emissioons, compettition with food
f
and tthe local app
plications off biomass, bbiodiversity, economic prosp
perityy, social welll-being, and
d environmeent. Elghali et al. (2007)) has
develloped a susttainability frramework foor the assesssment of bioenergy systems in terms of economic
e
viiability, envvironmental permance, and so
ocial acceptaability.
form
18
Smeets et al. (2006) have assessed sustainability criteria viz. The
ecological, economic and social impacts of sugarcane-based ethanol production in Brazil, compared using the Dutch sustainability
criteria. GHG balances, competition with food & energy supply,
biodiversity, wealth, welfare and the environment were used as determining criteria. These criteria might also be useful to establish a
product certification system for the international market. Environmental or ecological impacts cover water use, water pollution,
land use, forest protection and biodiversity, soil erosion, greenhouse gas emissions and energy balance. On the other hand, socioeconomic criteria might include competition with food production,
number of jobs, income distribution and land tenure, wages, worker rights, child labour, social responsibility and benefits (Smeets et
al., 2006).
Goldemberg et al. (2008) have discussed the sustainability of ethanol production from sugarcane, considering air quality improvement, rural development, biodiversity, deforestation, soil degradation, water source contamination, food vs. fuel production, and labour conditions in the fields. They have also discussed sustainability aspects of ethanol production, namely environmental and social
factors, along with the following sustainability criteria, as suggested
by the Cramer commission (Cramer et al., 2006): (a) energy balance, (b) environment aspects, such as gaseous emissions from
sugarcane and ethanol production, or due to sugarcane burning),
water (water availability, water pollution - organic pollutants, inorganic pollutants), land use (expansion of sugarcane, land competition - ethanol versus food crops), soil, biodiversity; (c) social aspects and social impacts such as labour conditions, jobs creation,
wages and income distribution, land ownership, working conditions. Zhou et al. (2007) have selected four sustainability indicators
for assessing biofuels - economics, environment, energy, and renewability. The energy indicator represents how much energy is
required to produce biofuel and renewability is evaluated using the
rate of exploitation of natural resources, such as fuel-wood.
In this way, there is great concern over the sustainability of biofuel
in both developed and developing countries. For the Least developed countries (LDCs), whose main primary energy source is traditional biomass, issues of sustainability are quite high on the
agenda, since rural populations live in conditions of utter poverty
and do not have enough resources for economic growth.
19
3.3
Defining life cycle
assessment (LCA)
Life cycle assessment (LCA) is a concept used to evaluate the environmental performance of a product or service during its entire
life span. LCA is an holistic systems approach and takes into account the inputs and outputs of the entire production system, viz.
raw materials, energy and waste, at every stage, from resource extraction (raw materials acquisition) to the final utilization and disposal of the product. LCA has become important since it encompasses all the processes and environmental discharges during the
production phases of the product, thus avoiding the shift of environmental problems from one place to another along the production chain (USEPA, 2006). The results of LCA have increasingly
been used as a decision-making policy tool for the selection of
products, and for environmentally friendly product-certification.
Rebitzer et al. (2004) and Pennington et al. (2004) have elaborated
on LCA application and practices. ISO 14040 - standards/series
(ISO, 2006a and 2006b) also uses the LCA concept and methodologies. LCA comprises four phases: goal and scope definition, inventory analysis, impact assessment, and interpretation (see Figure
6a). Goal definition and scoping describe the objectives of the
analysis, the production processes and system boundaries. The
purpose of the study is measured as a functional unit. In the inventory analysis, the material inputs/outputs are identified and quantified, for example, natural resources (energy, land, water etc.) and
environmental releases (e.g. emissions or wastes). Human and ecological effects that occur due to resource usage/consumption or
emissions/waste released into the air, water or soil are taken into
account in the impact assessment. This phase reveals the contribution made by different impact categories, for example: resource
depletion, climate change, eco-toxicity, human and ecological
health, acidification, and eutrophication. Following the inventory
analysis and the impact assessment, the interpretation of the LCA
is ultimately carried out to select the product or service based on
the envisaged environmental performance and in order to comply
with the objectives of the study. Thus, LCA provides a comprehensive environmental overview of the product, from cradle to
grave.
20
There are lots of applications of the LCA concept in evaluating renewable and sustainable energy systems. The LCA concept and
methodologies have been widely applied in developing bioenergy
systems. Liquid biofuels are increasingly seen as potential substitutes for gasoline and diesel in transportation. It is, therefore, important to assess the environmental performance of biofuel production and consumption, and also to compare them with conventional fossil fuels. Several LCA studies and reviews have been conducted to investigate the impacts of the life cycle resource consumption and environmental burden of bioethanol production
from different feedstocks, and they are primarily focused on the
life cycle net energy balance and GHG balances (see, for example,
Shapouri et al., 2004; Macedo et al., 2008; Dai et al., 2006; Nguyen
et al., 2007a/b/c, 2010; Blottnitz and Curran, 2007; Gnansounou
et al., 2009; Cherubini et al., 2009; Hoefnagels et al., 2010;
Xunmin et al., 2009). In this thesis, the life cycle energy and
greenhouse gas (GHG) balances have been investigated for molasses-based bioethanol (MOE). Molasses are a low-value by-product
resulting from sugar production. The definition of system boundaries, local sugarcane growing practices, harvesting, factory operations and waste management, and allocation methods in LCA are
some of the key features of the sustainability assessment of bioethanol carried out for Nepal.
3.4
Integrating sustainability and
LCA
LCA conventionally covers environmental sustainability, but efforts have been made to extend the concept to cover the three pillars of sustainability, including economic prosperity and social integrity. The future of LCA is likely to encompass all aspects of sustainable development, and the life cycle costing will provide policy
decision-makers with information on investment and return, while
social aspects might include indicators of millennium development goals (MDGs) in a holistic approach (Hunkeler and Rebitzer,
2005). LCA analyses have been carried out for the sustainability
assessment of various products/services during the last decade.
For example, Heller et al., (2000) have scrutinized economic, social
and environmental dimensions of the US food system, taking into
account the interaction between LCA and sustainability throughout the life cycle. Zhou et al. (2007) have analysed single- and mul21
ti-dim
mension susstainablity asssessment ccriteria for th
he sustainab
bility
assesssment of fuuels in the liife cycle fraamework, including reneewaa sustainaability indexees.
bilityy indicators and
Fig.66(a)Life cyclee assessment
(LCA) frramework
Fig.6((b) Sustainab
bility assessm
ment
procedurre
Adopted from
f
ISO (20006)
Adopted frrom DETEC (2004)
(
Figurre 6: Integraation of LCA
A and sustaiinability asseessment
The conceptual framework and basic methodologgy guidelinee for
sustaainability asssessment inccludes relevaance analysiis, impact an
nalysis annd assessmeent optimizaation (DETE
EC, 2004). This
T can also be
appliied to bioeth
hanol produ
uction. The m
main aim off the sustainability asssessment iss to evaluate and optim
mize bioethaanol producction
and cconsumption in relation
n to the targgets of sustaainable deveelopmentt. Sustainabiility assessm
ment is also a systemattic and com
mprehensiive approacch, and the relevance aanalysis deteermines the sustainabbility criteria in detail. Impact
I
anallysis evaluattes whether sustainabble developm
ment has beeen achievedd or not. Fin
nally, the sysstem
is opptimized forr further im
mprovement. These step
ps are show
wn in
Figurre 6b. Linkaage or integgration seem
ms importan
nt when the system ccan also be optimized with
w the hellp of objecttive function
ns to
securre the best, most envirronmentallyy benign op
ptions (Azap
pagic
and C
Clift, 1999). In this wayy, there is a cclose link beetween life cycle
c
22
assessment and sustainability assessment of biofuel production
(see Figure 6). Moreover, Zah et al., (2009) have recently outlined
an idea for the standardization and simplification of life cycle assessment, as a driver for more sustainable biofuels, using a webbased sustainability check-list for benchmarking sustainability criteria. This should help developing countries conduct LCAs of biofuels when product-certification schemes become mandatory.
3.5
Development of
sustainability criteria for
bioethanol production
The literature has been reviewed to find out more about the sustainability indicators of bioethanol production. Yan and Lin (2009)
have mentioned energy security, climate change, rural development
and poverty alleviation as the driving forces of sustainable biofuel
production. The energy and food security debate is crucial when
discussing the sustainability assessment of bioethanol since agricultural land is used to produce feedstocks, and these same feedstocks
can alternatively be used for food production, such as sugarcane
and corn. Biofuel and food prices have become an important factor in Asia when considering biofuel production, due to their conflicting nature, in terms of price, which could subsequently lead to
political instability (Zhou and Thomson, 2009). Sheehan (2009)
has mentioned that LCA is used for assessing the sustainability of
biofuels not only when it comes to net energy balance or the carbon footprint, but also expanding it to include global land and water resources, global ecosystems, air quality, public health and social justice. As he has shown, analytical frameworks for LCA and
sustainability assessment for biofuel have received increased attention in recent years. Research on the topic 'biofuels and sustainability' and 'ethanol and life cycle' have increased six-fold and threefold respectively from 2006 to 2008 (Sheehan, 2009). Smeets et al.
(2008) have evaluated the environmental and socio-economic impacts of the production of ethanol from sugarcane in the state of
Brazil for the purposes of product certification. Phalan (2009) has
given an overview of the social and environmental costs and benefits of biofuels in Asia, and the major factors identified were land
use, feedstocks used, technology issues and scale. According to
Schubert and Blasch (2010), bioenergy can only play an important
role in greenhouse gas (GHG) reduction when it is produced in a
23
sustainable way, thus the biofuel-pathways with minimum environmental and socio-economic problems should be promoted. Initial subsidies could also be instrumental in promoting environmentally benign biofuel promotion processes. Government policies, such as mandatory blending targets, tax exemptions and subsidies are the driving forces for biofuels production in many countries (Sorda et al., 2010). The development and selection of the
sustainability criteria for bioenergy depends on feedstock characteristics and different production pathways. Buchholz et al. (2009)
have also screened 35 sustainability criteria from a survey of experts, which are grouped into three pillars of sustainability. Regarding the experts’ views, which were based on attributes of relevance,
practicality, reliability, and importance, only two criteria, namely
energy balance and greenhouse gas balance, were found to be the
most critical, and local social parameters such as compliance with
laws, food security, participation, human rights and social cohesion
were ranked lower down. Competition between food and bioenergy production, and deforestation were two of the sustainability criteria used in the potential assessment of modern bioenergy sources
in one of the least developed countries (LDCs) in Africa Mozambique (Batidzirai et al., 2006)
3.5.1
Identification of sustainability indicators
for bioethanol in Nepal
Within the context of the sustainability assessment criteria for bioethanol production in the least developed countries (LDCs) such
as Nepal, the scarcity of commercial transport fuels, the flow of
hard currency, with state-subsidies on the imports of petroleum,
and local air pollution in urban cities are motivating factors for using a blend of bioethanol in gasoline. Energy security and the diversification of transport fuels, along with issues of food security
(i.e. sugar), environmental problems, such as water pollution, and
GHG emissions, play a vital role in the sustainability of bioethanol.
Employment generation in sugarcane cultivation and industrial operations, and the use of domestic resources for economic growth
at a local and regional level are to be assessed when evaluating the
sustainability of bioethanol. The technical viability of bioethanol
production is also important. Empowering local communities,
strengthening institutions among the concerned stakeholders and
24
political stability are all necessary for sustainable development of
bioethanol in Nepal.
Thus there are many different and important criteria to be considered in this context. This thesis focuses on some of the most important sustainability criteria. An overview of the indicators identified is presented in Table 1. The indicators marked with an asterisk
(*) are the focus of the present study. Many of the other criteria
have been discussed from a sustainability point of view, but more
as a means of analysing and defining the problem, thus lacking the
necessary depth for arriving at major conclusions.
Table 1: Selected sustainability criteria for evaluating the appropriateness of bioethanol production and use in transport
– the case of Nepal
Environmental
Economic
Social
Others
Fossil fuel substitution
Life cycle energy balances
CO2 emissions from fuel substitution in automobiles
Life cycle GHG balances
Local air pollution
Wastewater management
Change in land use pattern
Soil pollution
Utilization of natural resources
Protecting forests (avoiding deforestation)
Investment (costs and benefits analysis)
Savings on oil imports
Availability of resources (Capital)
Industrial growth
Agriculture growth
Energy security and diversification
Improved trade balances
Economic instruments: subsidies/tax exemptions
Carbon trading (under CDM)
Food vs. energy security
Employment generation, and wages
Rural and local development
Trade union, workers' facilities & safety
Poverty reduction
Equality, equity and cultural sovereignty
Institutional
Technical
Political
25
*
*
*
*
*
*
*
*
*
Two important sustainability indicators: net energy and greenhouse
gas (GHG) balances have been analysed in the life cycle framework. The economic and social factors of biofuel production,
which play a key role in determining the sustainability of bioethanol production, are also discussed so as to justify the research
questions and hypotheses of the thesis. However, this study is limited to evaluating the direct economic and social benefits. The life
cycle assessment of economic and social sustainability and the optimization of relevant sustainability indicators could possibly be the
scope of future analysis.
3.5.2
Defining net energy and greenhouse gas
(GHG) balances
Two important sustainability criteria – energy efficiency (net energy balances) and greenhouse gas (GHG) balances have been defined along the entire product-chain. The actual net energy and
GHG balances of bioethanol production in Nepal can then be estimated.
a. Net energy balance
Energy balances primarily deal with the life cycle energy efficiency
of bioethanol and the savings in non-renewable fossil fuels compared to bioethanol in the entire product-chain. There are defined
terminologies for dealing with energy balances. The net energy value or
balance (NEV or NEB) of bioethanol (EtOH) is the difference between the energy content of the bioethanol produced and the total
primary energy inputs (fossil plus renewable) in the entire fuel
production cycle.
NEV = EF î EI
where, EF is the energy content (lower heating value) of
ethanol, EI is the total amount of primary energy inputs
Net renewable energy value/balance (NREV) is calculated as follows:
NREV = EF î NEI
where, NEI is the non-renewable energy or fossil fuel input.
26
The energy yield ratio is defined as the ratio between the energy content of bioethanol and the total fossil energy required to produce
it.
energy yield ratio=
energy content in ethanol
fossil energy input
NREV and the energy yield ratio provide essential information
necessary to assess the contribution of biofuels to energy security.
The threshold limit is NREV > 1, while NEV gives and analysis
of the total input/output of energy, including renewable inputs. In
this study, energy recovered from by-products within the system,
i.e. excess bagasse and biogas are also incorporated into estimates
of NEV, NREV, and energy yield ratio.
b. Greenhouse gas balances
Total net emissions of greenhouse gases (GHG) are estimated
from greenhouse gas balances, including both release and absorption through the life cycle. The main GHGs considered in the
analysis are: carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The effect of these gases is measured using Global
Warming Potential (GWP), expressed in CO2 – equivalent (CO2eq.).
The estimation of GHG emissions is carried out by taking account
of the direct consumption of fossil fuels, the production of fertilizers/chemicals, activities taking place on agricultural farm land,
operations in industrial premises, and the ultimate combustion of
fuels.
This thesis uses the life cycle assessment (LCA) methodology to
evaluate greenhouse gas (GHG) balances and avoided emissions
compared to conventional gasoline. Material and energy inputs,
and their GHG emissions in sugarcane farming (fertilizer application and irrigation), transportation, milling, fermentation, distillation and the dehydration processes are considered in the analysis.
The system boundary covers local agricultural practices, the harvesting of sugarcane, cane milling, the ethanol conversion phase
(through the fermentation, distillation and dehydration route), and
waste management.
The functional unit in LCA is a measure of quantified performance
of products or services, and it enables comparison between the
27
products / services under consideration. GHG emissions in terms
of the kgCO2eq m-3 (also, in kgCO2eq MJ -1) functional unit are evaluated without considering the mechanical efficiency of the end user of bioethanol as the transport fuel. Material and energy flows in
the sugarcane bioenergy systems are normalized to this functional
unit.
Avoided emissions in the production and combustion/use of bioethanol (as the gasoline substitute) are estimated using the following equation, considering energy equivalencies of gasoline and bioethanol i.e. 1 GJ of bioethanol replaces 1 GJ of gasoline.
Avoided life cycle GHG emissions ሺ%ሻ
=
3.5.3
GHG emissions in gasoline-GHG emissions in bioethanol
x 100
GHG emissions in gasoline
Realization of a case study – sensitivity
analysis and development of scenarios
Sugarcane is one of Nepal’s cash crops, and 2.6 million tonnes of
sugarcane was produced from 64 thousand hectares of land, giving
an average yield of 40.6 tonnes per hectare in 2006/07. The trend
has been towards an increase in production, cultivation area, and
productivity since 1999/00. Nine sugar mills are operational with a
total installed capacity of 17,050 cane-tonnes per day, and are located in different districts of the fertile plain land of the South.
The sugar industry produces low-value molasses (4 - 5% of the
cane-stalk, w/w) as a by-product, which can be used for bioethanol production. At present, an ethanol plant with a production capacity of 30 m3 per day has been installed to produce molassesbased ethanol at Sri Ram Sugar Mills Pvt. Ltd. (SRSM).
In order to evaluate sustainability aspects of bioethanol production
in Nepal, a field case study was carried out at SRSM. Field data
based on material, energy, and waste flows (inputs and outputs) in
both agricultural practices and industrial operations are considered.
Figure 7 provides details of energy and material flows, including
emissions and waste at each stage along the ethanol production
chain in Nepal.
There are actually two main by-products in the sugar milling process: molasses and bagasse. Bagasse is used as the fuel input to
28
boilers. The steam from bagasse-fired boilers is used in power turbines to generate electricity, and the exhaust steam is utilized as the
heat required for the process of sugarcane milling, distillation and
dehydration. Molasses are converted into anhydrous ethanol fuel
(EtOH) via the route of hydrous ethanol (95% (v/v) ethanol,
called rectified spirit). The fermentation of molasses and the subsequent process of repeated distillation generate rectified spirit. To
produce anhydrous ethanol (99.5% v/v), rectified spirit (95% v/v)
is passed through a typical molecular sieve dehydration column/plant and following this the anhydrous vapour of EtOH are
condensed and cooled down to produce the final bioethanol.
Distillery waste water effluent (spent wash) is treated prior to disposal since treatment is essential from an environmental point of
view. An anaerobic effluent treatment plant generates biogas,
which is later used as a fuel, which is input into the boilers. Bagasse, which is used to generate steam for electricity and the heat
production, is considered as a source of renewable energy input into the system. Thus, bioethanol is only produced from low-value
molasses in Nepal at this point. Sugar juice is mainly dedicated to
the production of sugar.
In LCA, economic allocations are used to divide the resource consumption (primary energy), and environmental burdens (GHG
emissions) in upstream operations when we get co-products (sugar
and molasses). The market prices of sugar and molasses determine
the division of energy consumption, and greenhouse gas (GHG)
emissions between these two products. The average allocation ratio was found to be 22.2:1.
Figure 8 (a-j) shows actual field conditions in agricultural practices,
transportation of feedstocks, and factory operations, including the
generation of the co-products. SRSM is the only plant in Nepal
which has an installed molasses-based ethanol conversion unit, and
associated ancillaries such as wastewater treatment with biogas recovery. Therefore, factory operations for molasses-based ethanol
conversion in SRSM are considered to be the best available ethanol
plant in Nepal.
In order to cover the effect of variations in input parameters, such
as fertilizers, diesel consumption for irrigation, allocation ratio (i.e.
the prices of co-products), and agricultural yields, sensitivity anal29
yses have been performed for estimating both net energy and
GHG balances. Scenarios have also been developed at the plant
level to evaluate the consequences of adopting different
wastewater treatment processes, with or without biogas recovery,
and selling surplus bagasse electricity to the grid.
30
Figuree 7: System boundary an
nd material fflows (per hectare)
h
for sugars
cane-based systems iin Nepal
31
a. Sugarcane plantation, grrowth, and haarvesting are donne by human labour;
l
main materim
al inputs aare fertilizers, pesticides, in
nsecticides, and diesel (to op
perate water pumps
p
for irrigatiion). The totaal duration req
quired
for sugarcaane growth is 11-12 months, and
harvesting time lasts up to five months. Average prodductivity is 40..61 tonnes per hectare.
b. Transportation: Different
D
modees of transportt for carrying sugarcane feed
dstock
to tthe factory gatee; they includee animal-powerred cart (50%)), tractor (30%
%), and
trucck (20%).
c. Feeeding of feedsttock into
the milling processs
d. Open
O
burningg of sugarcane wastes (top
ps and
leaves)
l
e. Industrial compplex – Sri Ram
m Sugar Millss. Pvt.
Lttd. (SRSM) runns for about 5 months durin
ng the
haarvesting seasoon of sugarcan
ne. Industrial operao
tio
ons include suugarcane millin
ng, which pro
oduces
sugar as the maiin product, an
nd molasses an
nd bagasse as co-prodducts. Bagassee is separated during
d
the crushing off sugarcane wh
hile molasses is obtaiined at the cryystallization/ceentrifugal process.
f. Coggeneration plant: Bagasse-firred industrial boilers (left), and steam turbines
(righht) to generatee heat and elecctricity requiredd for the plantt
32
g. Geeneration of suugar: The yielld is
7 – 9 % of the suugarcane crush
hed.
h. Genneration of baggasse: a co-prroduct
of thhe milling pro
ocess and the yield
y
is
35 – 37% of the cane
c
crushed.
i. Disttillation plant (left) – molassses based biooethanol (95%
% v/v ethanol)), and
Deehydration plaant (right) - molasses
m
based bioethanol (999.5% v/v eth
hanol).
Appprox. 120 ton
nnes of molasses (42% w/w
w - fermentablle sugar) is req
quired
to generate 30 m3 of ethanol in
n the distillatioon plant.
j.j Effluent (w
wastewater or spent-wash) treatment plantt where reducttion in environ
nmental load occcurs along witth the generatiion of
biogas, whhich is later ussed as fuel inp
put in
the boilerss. 0.53 Nm3 of
o biogas (68%
% methane) is pproduced per kg of COD reducr
tion. In thhe present statte-of-the-art case in
SRSM, 1000% biogas is recovered from
m the
Anaerobic Digestion Pro
ocess (ADP) and directly fed in
into boilers.
Figurre 8 (a – j): Realization
n of the casee study in Nepal:
N
sugarrcane
a factory operations
farming and
Photograp
phs: Author’s field visit at Sri Ram Suggar Mills Pvt. Ltd.
(SRSM), Nepal
N
33
4 Re s u l t s a n d D i s c u s s i o n s
4.1
Overview
In this chapter, the findings of the research and case study are discussed. The results of the evaluation of the net energy balances,
energy yield ratios, and GHG balances are presented for the case
of Nepal. Sensitivity analyses are performed taking into account
economic allocation, material inputs, energy consumption, and
sugarcane yield. Different scenarios for the treatment of
wastewater and the case of surplus electricity derived from bagasse
are also dealt with for the purposes of evaluating GHG balances.
Finally, important sustainability aspects of the production of molasses-based bioethanol are discussed and summarized. The various steps taken in the calculations are explained in detail in the following papers: Khatiwada and Silveira (2009), Khatiwada and Silveira (2010), and Silveira and Khatiwada (2010) which are annexed
at the end of this thesis.
4.2
Life cycle net energy balances and
total energy yield ratio
In the case of sugarcane farming in Nepal, the primary energy consumption (per hectare) is 45,371.6 MJ (see, Table 2). The share of
fossil fuel and renewable energy inputs are 67.5% and 32.5% respectively. Out of the fossil fuel inputs, diesel used for irrigation
contributes 43.2% and fertilizers/chemicals comprise 45.7%. Since
transportation is mainly carried out using animal-driven carts, it
has only a small share, that is to say 5.9%, of total fossil fuel inputs. In the factory operations, 737.3 tonnes of bagasse is generated per day, which has a heating value (HHV) of 7,036.5 GJ. Bagasse and biogas supply energy for the plant’s processes. The sum
of the primary energy requirements of the different processes gives
the total energy demand.
34
Table 2: Primary energy requirement of one hectare of sugarcane farmland in Nepal (40.61 tonne/ha)
Activities
1. Sugarcane farming
Phosphorous
(P2O5)
Fertilizers
Potash (K2O)
Nitrogen
Pesticides/Insecticides
Herbicides
Diesel (irrigation)
Human Labor
2. Diesel (Transportation)
Sub-total (fossil and renewable)
Total
Fossil fuel inputs
(MJ/ha)
Renewable
energy inputs
(MJ/ha)
382.1
387.8
7,883.7
4,761.4
586.7
13,227.7
1,625
1,793.6
14,723.5
-
30,648.1
14,723.5
45,371.6 MJ/ha
Table 3 shows the primary energy balance in all the processes. The
sugar milling process consumes a large amount of primary energy
(73%). It should be noted that surplus bagasse amounts to 17%,
and is also taken into account in the calculation.
To produce one liter of anhydrous bioethanol (99.5% EtOH or
MOE), the life cycle energy input analysis shows that the renewable energy contribution amounts to 91.7% (31.42 MJ/L) since
most of the operations are run using bagasse, biogas and nonmotorized transportation. The only exceptions are the application
of fertilizers/chemicals and irrigation. Fermentation/distillation
consumes 12.63 MJ/L, which is the most energy intensive part of
the process, followed by sugar milling which consumes 10.46
MJ/L (see Figure 9).
35
Table 3: Primary energy balance of sugar milling in Nepal (including distillation, dehydration and ETP)
Processes
Sectors
GJ/day
Primary energy required
Sugarcane milling
Power (including electricity to facilities)
Heat
Fermentation/Distillation
Power
Heat
Dehydration
Power
Heat
Effluent treatment plant
Power
(ETP)
Lighting in the distillation,
dehydration, ETP plus
Power
electricity in their facilities
Total primary energy required
990.3
4,600.0
73.8
240.2
78.1
54
32.8
54.5
6,123.7
Primary energy supply
Bagasse primary energy input
ETP biogas input
Total primary energy input
Excess bagasse
% excess bagasse
7,036.5
319.3
7,355.8
1,232.1
16.75 %
Taking the energy content of anhydrous bioethanol (EtOH) to be
21.2 MJ/L, the net renewable energy value (NREV) is positive
(18.36 MJ/L) but the net energy value (NEV) is negative (î13.05
MJ/L). The higher positive value of NREV shows that the amount
of fossils fuels used in the production cycle of bioethanol is quite
low. In fact, the ratio between the energy content of bioethanol
fuel to fossil fuel inputs (energy yield ratio) is 7.47. However, the negative value of NEV shows that more energy is required to make
EtOH than there is in its final energy content. In any case, low
quality biomass feedstock, i.e. molasses (in terms of market and
energy values), is converted into a high quality commercial energy
carrier - bioethanol.
36
Figurre 9: The co
ontribution of
o fossil andd renewable energy requ
uired
to prodduce 1 literr of EtOH (MOE) in Nepal, at each
stage off the ethano
ol productionn chain
4.2.1
Sensitivity analysis (net energy
balances)
Sensiitivity analysses are perfo
ormed to finnd out the effect of (a)) the
economic allocattion ratio, an
nd (b) energgy consumption (power and
y
ratio.
proceess heat) on the net eneergy values aand energy yield
(a) V
Variation of allocation
a
ratioo related to moolasses price
The price of mo
olasses is qu
uite low in Nepal. As the
t demand
d for
e
incrreases, it cann be expecteed that the price
p
molaasses-based ethanol
of m
molasses will rise. The prrice of molaasses has beeen increased by
50%,, 100%, 150% and 200%
% to see thee effect on th
he energy vaalues
and eenergy yieldd ratio, whilst the pricee of sugar iss assumed to
o be
consttant. It has been found
d that the neet energy vaalue (NEV),, net
renew
wable energgy value (NR
REV), and energy yield
d ratio also
o de37
creasse with an in
ncrease in th
he price of m
molasses, seee Figure 10 (a-c).
(
For eexample, a 100% increaase in the pprice of mollasses leads to a
reducction of 90.22% in the NEV
N
and 14..7% in the NREV
N
with correspoonding enerrgy values of (-24.83) M
MJ/L and 155.66 MJ/L. The
energgy yield ratiio is also reeduced to 3..88 (a 48.8%
% reduction
n). A
higheer value for the energy yield
y
ratio eqquates to a higher merit for
the fu
fuel.
Figurre 10 (a-c): Effect
E
of changes in thee price of mo
olasses on
NEV, NREV,
N
and the energy yyield ratio
38
(b) E
Energy consum
mption in the plant
p
is reducedd
In thhe factory op
perations, th
here is signiificant poten
ntial to improve
the eenergy balan
nce of the prroduction oof bioethano
ol in Nepal. One
impoortant way to
o achieve th
his is to savve energy (p
power and heat).
h
Figurre 11 showss the variatio
on in NEV
V resulting frrom a reducction
in thhe plant’s en
nergy consum
mption. It hhas been found that a 10%
reducction in eneergy consum
mption in tthe plant heelps to incrrease
NEV
V by 33.5%.. The breakkeven point,, when NEV
V reaches zero,
z
occurrs at a 30% reduction in
n energy connsumption. Although th
his is
possiible from a technologgical point of view, itt is difficullt to
achieeve given thee current tecchnological settings of the
t plant.
Figurre 11: Effecct of different levels off energy con
nsumption
at the ethanol plant on NEV values
4.3
L i f e c y c l e GH G b a la n c e s an d a v o id e d
emissions
GHG
G emissionss (per hectarre) from suggarcane farm
ming are 36
625.3
kgCO
O2eq and thee contributio
on from diffferent activiities is show
wn in
Tablee 4. The shaare of produ
uction and thhe total app
plication of fertif
lizerss/chemicals is 55 %, while
w
diesel uused to pow
wer diesel water
w
pumpps and truckks/tractors constitutes
c
229.9%. Hum
man labour, cane
trashh burning, an
nd returned residues haave small shares of the total
emisssions, with figures
f
of 3.9%, 6.3% annd 4.9% respectively.
39
Table 4: GHG emissions from sugarcane farm land per hectare in Nepal (sugarcane yield: 40.61 tonne/ha)
Particulars
Production of fertilizers/ chemicals
Application of N-fertilizers
Human labour (fossil fuel inputs)
Use of diesel (irrigation and transportation)
Cane trash burning (dry trash)
Returned residues
Total kgCO2eq emissions per hectare
Emissions
(kgCO2eq Ha-1)
1013.34
982.45
142.12
% share
27.9
27.1
3.9
1082.72
29.9
228.43
176.20
3625.27
6.3
4.9
Table 5 shows the results of the estimation of GHG balances. The
life cycle greenhouse gas (GHG) emissions from the production of
1 m3 of molasses-based anhydrous bioethanol (EtOH) are 432.5
kgCO2eq, considering the best available molasses-based ethanol
conversion plant at Sri Ram Sugar Mills Pvt. Ltd. (SRSM), Nepal.
The net avoided emissions come out at 1418.4 kgCO2eq m-3 ethanol,
compared to conventional gasoline (of an equivalent energy
amount) which is a 76.6% reduction in the life cycle GHG emissions (see Table 6). Moreover, the life cycle emissions of EtOH
measured as a functional unit, per MJ, is 20.42 gCO2eq MJ-1.
Fossil fuels used in the production of fertilizers/chemicals, diesel
combustion (in water pumps and trucks/tractors), and human labour contributes 51.9% (224.4 kgCO2eq) of the total emissions. Soil
emissions from fertilizer-application and returned residues is the
second largest source with a share of 26.8% (116.1 kgCO2eq).
Emissions from boilers as a result of bagasse/biogas combustion,
trash burning, and combustion of ethanol in vehicles all correspond to small shares.
Total life cycle GHG emissions have been calculated to be 1251
kgCO2eq m-3 ethanol when all the sugarcane is used to produce bioethanol (without sugar), considering that 1 tonne sugarcane produces 80 liters of ethanol. It should be noted that the allocation
has not been made here since bioethanol accounts for the entire
GHG share in this case. Avoided emissions are 599.7 kgCO2eq m-3
ethanol or a 32.4% reduction in the life cycle GHG emissions
compared to gasoline, thus much lower than the case of molassesbased ethanol.
40
Table 5: Life cycle GHG (CO2eq) balance of molasses-based ethanol (MOE, EtOH) fuel in Nepal
Emissions
(kgCO2eq m-3)
Activities and constituents
Fertilizer production
Phosphorous (P2O5)
Potash (K2O)
Nitrogen (N)
Chemical production
Insecticides/pesticides
Herbicides
Diesel (irrigation): production & combustion
Diesel (transport): production & combustion
Fertilizer application
N2O from fertilizer N-application
CO2 from fertilizer N-application
Human labour (fossil fuel inputs)
Cane trash burning
N2O (spent wash/stillage)
Returned
N2O (filter cake/mud)
residues
N2O (unburned trash)
Bagasse combustion in boilers (for heat & power)
Biogas combustion in boilers
Sub-total (emissions along the ethanol production
chain)
Emissions from combustion of 1 m3
ethanol
(EtOH) in vehicles
Total life cycle emissions (production & combustion of EtOH)
5.95
3.89
48.92
38.66
4.16
95.57
12.96
76.11
22.37
14.25
22.90
1.06
9.13
7.48
35.57
8.56
407.53
25.00
432.53
Table 6: Life cycle comparison of GHG emissions, ethanol
(EtOH) and gasoline
Equivalent fuels (EtOH and gasoline)
Emissions from production and combustion, 1 m3
ethanol (EtOH)
Emissions from production and combustion, 0.658
m3 gasoline
(= 1 m3 of EtOH)
Net avoided emissions (kgCO2eq EtOH)
% reduction in life cycle GHG emissions
41
Emissions
(kgCO2eq)
432.53
1850.95
1418.42
76.63
4.3.1
Sensitivity analysis (GHG balances)
) Variattion of allocaation ratio reelated to molassses price
Sensiitivity analysis shows how
h
the lifee cycle GHG
G emissionss increasse when thee market priices change towards a higher
h
pricee for
molaasses. Figuree 12 depicts the result off GHG emiissions, coveering
the w
whole range of sensitiviity from thee allocation ratio
r
of 24 to
t 4.
It should be notted that the average alloocation ratio
o, considereed to
be thhe normal base
b
case for analysis, w
was 22.2. When
W
the maarket
pricee of molassees increases two-fold, tthe new allo
ocation ratio
o i.e.
10.888 (keeping the market price of suugar constaant) would give
844.77 kgCO2.eq m-3 ethanol which
w
is a 554.4% reduction in thee life
cyclee GHG emissions comp
pared to gassoline (also,, see Figure 12).
The full trade-o
off situation, i.e. when the life cyccle emission
ns of
ethannol are the same as tho
ose of conveentional gassoline, occurrs at
an alllocation ratiio of 4.43 (b
break-even ppoint). Below
w this point,, it is
not eeconomicallyy viable to produce
p
moolasses-based
d ethanol in Nepal.
Figurre 12 : Sensiitivity analyssis for life cyycle GHG em
missions and
avoideed emissions (%) as a fuunction of different
d
allocation raatios for suggar and molaasses
(Note: Dots on the primary
p
and se condary y-axiss represent thee total
ons and % avo
oided emissionns respectively at the base caase alemissio
location
n ratio, i.e. 22.2:1 (molasses: sugar)
42
) Alternaation of material/ener
m
rgy inputs, and sugarrcane
yield
Withh a variation
n in the threee importannt input paraameters, nam
mely
consuumption of pesticides, nitrogen-fert
n
rtilizer, and diesel
d
(for irrigation),, the life cyccle GHG em
missions havve been estiimated. Thee parameeters have beeen varied frrom a 75% rreduction to
o a 75% incrrease
from
m the presentt value. Figu
ure 13 show
ws the resultss of the anallysis.
It cann be observved that thee productionn and appliication of nitrogen-ffertilizer hass a higher im
mpact on GH
HG emissio
ons than thee use
of dieesel and pessticides. Forr example, a 50% increaase in the usse of
nitrogen-fertilizeer will lead to
t an increaase in GHG
G emissions to a
-3
level of 506 kgC
CO2eq m ethaanol, while ddiesel consuumption and
d the
appliication of peesticides wo
ould only inccrease the emissions
e
to 480
and 4452 kgCO2eqq m-3 ethanoll respectivelyy. On the otther hand, when
w
sugarrcane yields are improvved, there iss a significaant reduction in
the liife cycle GH
HG emission
ns (see also Figure 13). A 75% incrrease
in thee cane yield (i.e. 71 tonn
nes per hecttare) from th
he present value
v
of 400.61 tonnes//ha could reeduce GHG
G emissions to 306 kgC
CO2eq
m-3 eethanol (14.4 gCO2eq MJ
M -1) and avvoided emissions would
d be
83.5%
% comparedd to gasolinee. Cane yieldds are curren
ntly quite low in
Nepaal. Thereforre, there is plenty of scope for immediate improveements.
Figurre 13: Sensittivity analyssis for variattions in matterial/energyy inputs and sugarcaane yield in Nepal
43
4.3.2
Alternative scenarios and system
expansion
) Alternative scenarios in wastewater treatment plants
GHG emissions from wastewater (effluent or spent wash) treatment plants at the factories/distillery plants are quite significant,
and are related to the types of treatment process used. The Anaerobic Digestion Process (ADP, a biological digester) and Pond Stabilization (PS, also called the lagoon system) are two common
treatment practices for the treatment of wastewater from sugar and
distillery industries. The present scenario (at the plant level) in
SRSM comprises the best available case in Nepal with wastewater
treatment facilities treating 100% of the wastewater, using ADP to
recover biogas, whereby no leakage of biogas is allowed into the
atmosphere. Recovered biogas is fed directly into boilers as fuel.
Given a scenario of 100% biogas leakage into the open atmosphere from ADP, the total amount of emissions would be 2602.1
kgCO2eq (per hectare). The Pond Stabilization (PS) process releases
1551.4 kgCO2.eq Ha-1 into the atmosphere. A close examination of
the GHG emissions associated with each of these waste treatment
options shows that the ADP treatment process, without any biogas
leakage, is preferred.
The results of emissions from ADP and pond stabilization (PS)
treatment plants have been scrutinized. When 100% of the spent
wash is sent through the pond stabilization process, the life cycle
emissions may increase to 118% with a value of 4032 kgCO2eq m-3
ethanol. When 50% of the spent wash is treated using PS and the
remaining 50% fed into the ADP (with biogas recovery), there is a
21% increase in emissions, compared with those for gasoline.
However, if 25% of the spent wash is treated using PS and the remaining 75% with the ADP, the emissions are reduced by 28% to
a level of 1332 kgCO2eq m-3 ethanol, as shown in Figure 14. Thus,
the installation and operation of the ADP in sugar and distillery
factories not only recovers energy but also reduces the life cycle
GHG emissions.
44
Figurre 14: Life cycle emissiions in the case of parrtial treatment of wastewatter in PS andd ADP
Whenn considerin
ng the leakaage of bioggas from a bio-digester
b
(i.e.
from
m ADP), 10%
% leakage would
w
avoid 44% of thee life cycle emissionss compared to gasolinee. In this caase, the vallue of life cycle
c
GHG
G emissionss becomes 1038 kgCO
O2eq m-3 ethaanol. Figuree 15
show
ws the total emissions, taking into account bio
ogas leakagees in
the raange of 5 – 25%. If thee total leakagge of biogass exceeds 23
3.4%
then the life cyccle GHG em
missions of bioethanol will surpasss the
emisssions level of its coun
nterpart, connventional gasoline.
g
Th
herefore, it is essentiial to avoid leakage in oorder to takke full advan
ntage
f
fuel subbstitution.
of thhe emissions reduction from
) Grid connection
c
for
fo electricityy from exceess bagasse and
technoloogical improvements
As foound in the estimation of
o the net ennergy balancces, there is 17%
excesss bagasse arising
a
from
m the sugar pproduction chain at SR
RSM.
Sugarr mills/facto
ories in Nep
pal are locatted near to industrial corridors where manyy industrial complexes ooperate. The industries suffer frrom power shortages, especially
e
inn the dry seaason (Decem
mber
– Maay), the perio
od when hyydroelectricitty generatio
on is limited and
45
the hharvesting of sugarcan
ne occurs. Industries, therefore, run
standd-by diesel power
p
plantts when no electricity iss available from
f
the ggrid. Excesss bagasse caan be used tto generate and
a supply elece
tricityy to the gridd along thesse industrial corridors. Part
P of the elece
tricityy produced by the dieseel power plaants can be replaced byy this
renew
wable bioellectricity with a conseequent reduuction in GHG
G
emisssions. It sho
ould be notted that boillers and turbines with their
t
curreent installed capacities can operate iin such a waay as to geneerate
excesss electricityy though im
mproved eff
fficiency, wh
hich would add
both economic and
a environm
mental valuee.
Figurre 15: Life cyycle emissio
ons in the caase of biogass leakage
Withh the avoidan
nce of GHG
G emissions through thee substitutio
on of
dieseel-based elecctricity, the total
t
emissioons of ethan
nol are negaative
(-2133 kgCO2eq m-3 ethano
ol) indicatinng that thee entire su
ugarcane//ethanol pro
oduction-ch
hain absorbs GHG ratheer than releaasing
emisssions into th
he atmosph
here. The tootal percentaage reductio
on in
GHG
G emissions is 112% baased on the production of 1 m3 of molassess-based ethaanol (EtOH)), when com
mpared with
h gasoline. Emissionss from differrent activitiees are shownn in Figure 16. It should be
notedd that the avoided
a
GH
HG emissioons are not partitioned betweenn sugar andd molasses when
w
considdering the exxpansion off the
46
system
m with surrplus electriccity. Sugar aand molasses actually emit
618 kgCO2eq an
nd 28 kgCO
O2eq at an alllocation rattio of 22.2:1 as
show
wn in Figure 16.
Techhnological im
mprovementts in the baggasse-fuelled
d combined heat
and ppower plantt (CHP), such as a highh pressure and
a temperaature
turbinne, can geneerate 1 kWh
h electricity ffrom 1.6 kgg of bagasse (Purohitt and Michaaelowa, 20077) which is m
more than five times more
m
resouurce efficien
nt than the ones foundd in Nepal.. Thus, therre is
huge potential to
o trade-off the
t entire G
GHG balancces in the su
ugarcane systems off Nepal by generating and selling bagasse-fueelled
bioellectricity to replace
r
dieseel power plaants. The uttilization of cane
trashh/wastes forr electricity generation, and the im
mprovement and
optim
mization of industrial processes
p
c ould furtheer reduce GHG
G
emisssions.
Figurre 16: GHG
G emissions shares from
m different sttages of the ethanol production
p
chain in N
Nepal (in the case of using
u
surpluus electricityy to substitutte diesel)
47
4.4
Comparison of results with other
studies
Several studies have estimated the life cycle energy and GHG balances of bioethanol derived from various feedstocks, such as sugarcane, cassava, corn and cane-molasses. Macedo et al., (2008)
found that the energy yield ratio in the production phase of sugarcane was 9.3 in Brazil during 2005/06, taking into account the direct consumption of external fuels and electricity, the energy required for the production of chemicals and materials, and the additional energy necessary for the manufacture, construction and
maintenance of equipment and buildings. The total GHG emissions for anhydrous ethanol production were 436 kg CO2eq m-3
ethanol in the same period and could decrease to 345 kgCO2eq m-3
for a conservative scenario in 2020 (Macedo et al., 2008). Cane
productivity and ethanol yield were the most important parameters
affecting the estimation of GHG balances. However, the study
has not dealt with wastewater treatment of spent wash.
Nguyen et al. 2007a have calculated the NEV and NREV for cassava-based bioethanol in Thailand with respective positive values
of 8.8 MJ/L and 9.15 MJ/L. Shapouri et al. (2004) reported that
the net energy balance (energy yield ratio) for producing corn ethanol in the USA was 1.67. The results of NEV and NREV for cassava fuel ethanol, as reported by Dai et al. (2006), were 7.47 MJ/L
and 7.88 MJ/L respectively, in the case of China. Nguyen et al.
(2008b)’s life cycle analysis of sugarcane-molasses-based ethanol
calculated the values of NEV (-5.67 MJ/L), NREV (5.95 MJ/L),
and energy yield ratio (6.12 per MJ petroleum inputs) in Thailand.
The study was quite similar to that of molasses bioethanol in Nepal. However, the results contrast with the values of NEV (-13.05
MJ/L) and NREV (18.36 MJ/L) found in the Nepalese case. In
the Thai case, the plant’s energy requirements are not met by bagasse alone; rice husks and wood wastes are also used as supplementary fuels in the sugar milling process. Coal is a major fuel in
the ethanol conversion process, and biogas is not utilized for process energy. At the same time, excess electricity is sold to the grid
as energy outputs. In the case of Nepal, the difference in NEV is
due to higher total energy inputs (fossil fuel plus renewable) while
favourable conditions for NREV occur, since energy requirements
are mostly met by renewable sources.
48
Nguyen et al. (2007b) have analysed the life cycle GHG emissions
for molasses-based ethanol in Thailand, demonstrating that there is
a 31.3% increase in GHG emissions (per liter of ethanol) with an
allocation ratio (between sugar and molasses) of 8.6:1. Emissions
from anaerobic pond stabilization contributed the largest share, of
54.1%. However, the study also showed that biogas recovery from
100% spent wash could reduce GHG emissions by 60.6% compared to conventional gasoline, and further improvements are possible, up to an 88.8% reduction. In comparison, a 76.6% reduction
in total emissions per liter of ethanol is observed in the Nepalese
case, assuming the best case currently available in one of the established sugar factories.
Greenhouse gas savings (tonnes of CO2eq per hectare) in sugarcane
bioenergy systems have also been identified by Nguyen et al.
(2010) in the sugar industry in Thailand. Electricity generation
from cane trash/residues and excess bagasse, and energy extraction from stillage (wastewater) would reduce GHG emissions.
When considering molasses as a feedstock for ethanol production
in the average Brazilian mill, Gopal and Kammen (2009) found
that the life cycle GHG emissions were 15.1 gCO2eq MJ-1 , and
sugar and molasses prices play a key role in determining the
emissions. In comparison, emissions of 20.4 gCO2eq MJ-1 of GHGs
were found in the case of Nepal, for sugarcane-molasses-based
ethanol. The life cycle emissions in the production and use of 1 m3
of cassava-based ethanol were 964 kgCO2eq, which corresponds to
62.9% of the total reduction in emissions Nguyen et al. (2007c).
Moreover, Blottnitz and Curran (2007) conducted a review of
assessments of bioethanol as a transporation fuel from the net
energy, greenhouse gas and environmental life cycle perspective,
comparing energy yield ratios and GHG balances, though with
differing assumptions and system boundaries. The values of GHG
emissions and energy yield ratios differ significantly depending on
the feedstock used and the production practices applied. Recent
literature also points out that it is essential to distinguish between
the bioenergy systems referred to, the energy conversion
technologies used and the resultant energy and GHG balances,
when contrasting LCA and sustainability issues for different
biofuels (Gnansounou et al., 2009 ; Cherubini et al., 2009; Hoefnagels et al., 2010). These studies are important points of reference
for the evaluation of biofuels, but an in depth comparison of the
49
energy values and GHG emissions of ethanol production methods
is difficult without precisely defining the methodological approach,
system boundaries, allocation methods, and specific feedstock
characteristics, among other things. Thus, unified methodological
procedures in the production of bioethanol are required globally,
including LDCs.
4.5
Prospects for sustainable
development
Nepal has great potential to produce molasses-based ethanol and
for it to be used as part of a blend in gasoline-run vehicles. The increased use of biofuels not only reduces dependency on fossil fuels
but also reduces the greenhouse gas (GHG) emissions and local air
pollution caused by vehicular emissions. In addition, the production of biofuels can serve as a driver for improvements in agriculture. The prospects for sustainable development are discussed in
detail in Silveira and Khatiwada (2010). This section highlights the
key issues related to the potential for ethanol to contribute to sustainable development in Nepal.
4.5.1
Ethanol production potential in Nepal
With an installed production capacity of 30 m3 of bioethanol per
day, Sri Ram Sugar Mills Pvt. Ltd. (SRSM) can produce 4,500 m3
annually, assuming the plant runs for 150 crop days. If SRSM purchased molasses from other sugar mills, then the production capacity reaches 8,760 m3, assuming that the ethanol plant runs during the whole year at a plant utilization factor of 80%.
Of the total sugarcane production in 2006/07 (i.e. 2.6 million
tonnes), 70% was processed by sugar industries to produce sugar
in Nepal. 78,684 tonnes of molasses were generated, assuming an
average production of 4.3% of the sugarcane milling. Thus the bioethanol production potential was 18,045 m3 for the same year.
4.5.2
Substituting gasoline with E10 and E20 in
the Kathmandu Valley
The Kathmandu Valley consumes 71,338 m3 of gasoline (70% of
the gasoline imported to Nepal) per year. 56% of the country’s automobiles run in the valley. Most light automobiles, such as cars,
50
jeeps and vans, and a huge fleet of two-wheeler motor-bikes use
gasoline. Automobiles fuelled by gasoline can use E5-E20 blended
fuel in the existing engine with only minor adjustments, and it also
has a high octane number (ON) with better combustion efficiency.
When considering the energy content or lower heating value
(LHV), and the volumetric equivalency between the ethanol blend
(E10) and pure gasoline, i.e. one liter of pure gasoline is equal to
1.0354 liters of E10, it is found that the substitution of the gasoline
presently used in the Kathmandu Valley adds up to a total of
73,864 m3 of E10, which corresponds to a blend of 66,478 m3 gasoline and 7,386 m3 of ethanol. It should be noted that the LHV of
anhydrous ethanol (99.5% v/v, EtOH) and gasoline are 21.183
MJ/L and 32.192 MJ/L respectively. As examined by Silveira and
Khatiwada (2010), The Kathmandu Valley could save 4,860 m3 of
gasoline per year, which is a reduction in imports of 6.8% if gasoline automobiles went for E10. The demand for E10 could be met
if SRSM purchased molasses from other sugar mills and ran the
dehydration ethanol plant annually at a plant utilization factor of
68% assuming other sugar mills were not equipped to produce anhydrous ethanol (EtOH).
When the vehicles go for an E20 blend, a reduction of 14% in
gasoline imports, i.e. an annual saving of 10,078 m3, is achievable,
which corresponds to an ethanol requirement of 15,315 m3 in a
year. This annual requirement is still lower than the total potential
capacity of the sugar mills, given the availability of molasses for
ethanol production.
Looking at the economics of petroleum imports, Nepal Oil Corporation (a state owned enterprise, NOC) accumulated annual
losses of US$ 78 million in 2007/08, US$ 27 million in 2006/07,
and US$ 55 million in 2005/06. With the introduction of ethanol
blends, direct annual import savings of US$ 4.9 million (with E10),
and US$ 10.1 million (with E20) can be achieved, given the current
retail price of gasoline.
4.5.3
Environmental gains of introducing E10 and
E20 in the Kathmandu Valley
The Kathmandu Valley suffers from a severe air pollution problem
due to increased vehicular emissions and its specific geographic lo51
cation. Various international studies have shown that the use of
biofuels not only reduces dependency on fossil fuels but also reduces greenhouse gases and local air pollution caused by vehicular
emissions. In Nepal, the environmental life cycle analysis of an
E10 and pure gasoline car shows that E10 fuel works better than
pure gasoline with regards to greenhouse gas emissions, the release
of carcinogens, and ozone layer destruction, although the quantity
of substances causing acidification/eutrophication increases with
the E10 (Khatiwada, 2007). A piece of research conducted to investigate the performance of E10 and E20 in automobiles in the
Kathmandu Valley showed ethanol blends work better than conventional gasoline (AEPC, 2008).
The Kathmandu Valley consumed 71,338 m3 of gasoline, 46,003
m3 of diesel, and 5400 tonnes of LPG in the transport sector in
2006/07. The total CO2 emissions resulting from the consumption
of these transport fuels were estimated to be 304,000 tonnes (petrol: 54.4%, diesel: 40.3%, and LPG: 5.3%). The introduction of
E10 could avoid 11,283 tonnes (7% of total gasoline emissions) of
CO2 emissions, while E20 could contribute to the avoidance of
23,397 tonnes of CO2 emissions, which is 14% of the total gasoline emitted in a year in 2006/07 (Silveira and Khatiwada, 2010).
4.5.4
Other important aspects of sustainable development
First generation bioethanol, derived from food crops such as
corn/maize and sugarcane is often debated when it comes to food
security and land use. In Nepal, the production of bioethanol occurs from the low-value by-product of the sugar milling process:
molasses. Without compromising sugar and other indigenous sugar-based food products (such as Chaku and Shakhar), Nepal could
today produce enough bioethanol to introduce an E20 blend for
gasoline replacement in the Kathmandu Valley (Silveira and
Khatiwada, 2010). Therefore, there is no trade-off between food
and fuel in terms of bioethanol production in Nepal at its present
scale. Our study has also shown that there is still a significant potential to increase cane yields, which would guarantee a significant
increase in ethanol production without the need to bring more
land into cultivation.
52
Given the present conditions, sugar industries are self-sufficient in
their energy requirements. Bagasse generates the heat and electricity required to run the whole plant. Excess bagasse could be used
to provide surplus electricity to replace diesel-powered electricity
in the industrial corridor. Bioethanol derived from molasses could
replace gasoline in the transport sector. Having made more efficient utilization of bagasse and cane-trash, surplus bioelectricity
could be generated to provide power for nearby industries or to
provide lighting for the rural poor, with the help of rural electrification in the countryside, where 61% of the population still lack
electricity. Therefore, the development of sugarcane bioenergy systems would enhance energy security.
Of the total land area of 14.72 million hectares in Nepal, cultivated
land accounts for 21%, non-cultivated 7%, forest including shrubs
39.6%, grass land 12% and water bodies and others 20.4%. Cultivated land is used for cereal/food products, cash crops, pulses,
and fruit/vegetables. Cash crops consist of oilseed, potato, tobacco, sugarcane, and jute. The production of cash crops takes place
in 13.2% of the total cultivated land, of which 14.5% is allocated
for sugarcane farming. Thus, it can be observed that the area occupied by sugarcane is significantly smaller than the area dedicated
to other cash or food crops. At present, sugarcane yields reach an
average of 40.6 tonnes/ha, and could be improved with the help of
regional experience and practice in sugarcane cultivation. Mechanization of agricultural practices should also be considered in the
medium term. This would enhance food production as well as that
of energy products without the need for more cultivated land.
Wastewater (spent wash), generated by bioethanol conversion
units, is treated using an Anaerobic Digestion Process (ADP) with
biogas recovery, and the final effluents are only discharged into
water bodies, within acceptable limits, after the treatment has met
the effluent standards set out by the environmental protection
rules/regulations in Nepal. If the wastewater treatment plant is
properly operated and maintained, there will be no significant water pollution resulting from distillery operations.
The institutional collaboration between concerned private and
public stakeholders, including donor agencies/partners plays an
important role in the sustainability of any development project.
The institutional set-up and public-private-partnerships seem weak
53
in the case of Nepal. For example, government policy on the introduction of the E10 blend was enacted in 2004 but has not yet
been implemented due to institutional bottle-necks.
Nepal is currently at the verge of a period of political transition,
and internal conflicts still exist within the country, especially in the
plains of the south, which affects sugarcane production and
productivity. Proper renewable energy policy is required to boost
the production and use of bioethanol, providing on the one hand
incentives for sugarcane farmers and industries who want to make
the investment in bioethanol production and, on the other hand,
the proper institutional conditions to promote the switch to a new
fuel.
4.6 Results of sustainability assessment: a
summary sheet
With the above discussion on the development of sustainability
criteria, and the findings from the case of molasses-based bioethanol production and use in Nepal, a summary sheet of sustainability
criteria for bioethanol production is presented in Table 7. While
Table 1 indicated a large number of important criteria in the context of bioethanol production and use, Table 7 shows a summary
of the most important messages derived from the in depth analysis
carried out using some of these sustainability criteria. The second
column summarizes the main contributions or arguments of the
thesis, indicating what can be achieved in the short run.
54
Table 7: Evaluating selected sustainability criteria for bioethanol production and use in Nepal – Summary of thesis
results
Criteria
Contributions of the thesis
Life cycle energy balances
Fossil fuels substitution
11,283 tonnes and 23,397 tonnes of CO2 are avoided by substituting E10 and E20 for gasoline respectively.
Net renewable energy value (NREV) = 18.36 MJ/L; Net energy value (NEV) = - 13.05 MJ/L; Total energy
(fossil and renewable) inputs = 34.26 MJ /L; Energy yield ratio = 7.47
With the use of bioethanol blends in the transport sector, the consumption of imported gasoline is reduced.
Gasoline savings are 4,860 m3 (for E10) and 10,078 m3 (for E20) per year in the Kathmandu valley.
A. Environmental
CO2 emissions from fuel
substitution in automobiles
Life cycle GHG emissions = 433 kgCO2eq m-3 (or 20.4 gCO2eq.MJ-1.); net avoided emissions = 1418 kgCO2eq
m-3 ethanol or a 76.6% reduction in the life cycle GHG emissions compared to conventional gasoline
Molasses, a low-value by-product of the sugar milling process is used for bioethanol production without
compromising the production of sugar and other indigenous sugar based food products (such as Chaku and
Shakhar).
Direct annual savings are US$ 4.9 million (using E10) and US$ 10.1 million (using E20) in the Kathmandu
Valley
National bioethanol potential = 18 million liters. Bioethanol can replace imported gasoline, enhancing domestic energy security. Moreover, a combined heat and power (CHP) plant, fuelled by bagasse and recovered
biogas, provides energy at the plant level, while surplus bioelectricity can be sold to the grid.
Bioethanol blends reduce air pollution problems in the Kathmandu Valley
Examination of the wastewater treatment processes shows that it is essential to treat distilleries’ wastewater
(spent wash) using the Anaerobic Digestion Process (ADP) with biogas recovery. Biogas contributes 4% of
total available primary energy, and ADP (without biogas leakage) contributes to reducing life cycle GHG
emissions.
Life cycle GHG balances
Local air pollution
Wastewater management
B. Economic
Savings on oil import
Energy security and diversification
C. Social
Food vs. energy security
55
5 Conclusions and
future work
5.1 Conclusions
This study has estimated the net energy balance of the production
of molasses-based bioethanol in Nepal, examined the GHG balances associated with the production and use of bioethanol in the
country, and showed how bioethanol production and use can contribute towards sustainable development. The thesis now turns to
the three key questions that were asked at the beginning, as a way
of putting the analysis into perspective and drawing appropriate
conclusions.
(a) Is bioethanol energy efficient i.e. how much energy does it take to produce
one liter of bioethanol?
The fossil fuel required to produce 1 liter of molasses-based bioethanol (MOE or EtOH) is 2.84 MJ, giving a good energy yield ratio (7.47). The net renewable energy value (NREV) is 18.36 MJ/L,
and a higher value of NREV indicates the low amount of fossil
fuels used in the production cycle of ethanol in Nepal. Thus, bioethanol production is energy efficient in terms of the amount of
fossil fuel used to produce it. The total energy (fossil fuel and renewable) requirement is 34.26 MJ/L, which is higher than the energy content of 1 liter of bioethanol (i.e. 21.2 MJ/L), giving a negative NEV (î13.05 MJ/L). However, low quality biomass feedstock
i.e. molasses (in terms of market and energy values) is converted
into a high quality modern renewable transport fuel. In addition,
there is plenty of room for significant improvements in the short
term.
The life cycle renewable energy contribution amounts to 91.7%,
required to produce 1 liter of EtOH, since bagasse, biogas and
non-motorized transportation cover most of the operations with
the exception of the application of fertilizers/chemicals and irrigation. There is huge potential for energy savings in sugar milling
and ethanol production: a 10% reduction in energy consumption
56
helps to increase NEV by 33.5%. An improvement of 30% in the
efficiency of the plant will result in a break-even situation for
NEV, i.e. a point where the total energy input into the system is
equal to the output in terms of the energy content provided by bioethanol. This is fully possible with readily available technology.
(b) How many greenhouse gas (GHG) emissions and savings occur in the production and use of bioethanol?
The total life cycle emission of bioethanol is 433 kgCO2eq m-3 (i.e.
20.4 gCO2eq MJ-1), which is a 76.6% reduction in GHG emissions
compared to conventional gasoline from a life cycle perspective.
Thus, the production and consumption of bioethanol saves 1418
kgCO2eq m-3 of GHG emissions when an equivalent volumetric
amount (i.e. 1 m3 ethanol = 0.658 m3 gasoline) of gasoline is replaced by ethanol as the transport fuel in Nepal.
(c) What are the direct benefits of bioethanol substitution in the transport sector?
The direct benefits of bioethanol substitution in the transport sector are: replacement of gasoline fuel, enhancement of energy security, diversification of energy products, improvement of local air
quality in the Kathmandu Valley, saving hard foreign currency, and
a reduction in GHG emissions.
The variation in the price of molasses has a significant effect on
the net energy values, energy yield ratio, and GHG balances. When
the market price of molasses doubles, the energy yield ratio is reduced to 3.88 (a 48.8% reduction). NEV and NREV also decrease
by 90.2% and 14.7% respectively. On the other hand, the life cycle
GHG emissions would be 844.7 kgCO2eq m-3 ethanol given a twofold increase in the price of molasses.
The analysis of scenarios concerning the choice of wastewater
treatment plant, from either Anaerobic Digestion Process (ADP)
or Pond Stabilization (PS), shows that ADP with biogas recovery
significantly reduces GHG emissions, particularly if leakages are
avoided. The pond stabilization (PS) treatment process contributes to an alarming increase in GHG emissions. The expansion of
the system, with the sale of surplus electricity obtained from the
57
combustion of excess bagasse, could also help to reduce GHG
emissions.
This thesis has identified a number of opportunities for improvements to the net energy balance and GHG emissions along the bioethanol production chain. Improvements can be achieved
through: (a) improvement in cane yields, with the help of the modernization of agricultural practices, (b) cane bagasse and
trash/wastes being used efficiently to generate bioelectricity, and
(c) the technological upgrading and optimization of industrial operations. However, it is difficult to compare and benchmark these
improvements with similar studies carried out elsewhere due to a
lack of methodological coherence in evaluating bioethanol production globally.
In spite of the international debate on biofuels, bioethanol production in Nepal does not pose any threats to food security since the
feedstock is a low-value industrial by-product obtained from the
sugarcane milling process. Nepal can produce 18 million liters of
bioethanol annually without compromising the production of food
products, and savings of US$ 10 million could be possible through
the implementation of the E20 blend in the Katmandu Valley to
replace conventional gasoline. Vehicles running on ethanol blends
(E10 or E20) also release less air pollutants compared to pure gasoline.
It is envisaged that favorable governmental policies, such as mandatory bioethanol blends and incentives/subsidies for sugarcane
farmers and private investors, will be put in place to explore the
bioethanol potential in Nepal. Proper institutional mechanisms and
coordination amongst concerned stakeholders, including both private and public sectors, are required for the production and commercialization of bioethanol in Nepal. Both political and institutional concerns have become the most urgent issues to address at
this stage, when mature conversion technologies are already available and accessible in the region. The insight provided using the
example of this country could also motivate the assessment and
production of bioethanol in other LDCs.
58
5.2 Future works
(a) This research is focused on the direct economic and environmental benefits, along with the life cycle energy assessment and GHG balances of bioethanol production in Nepal.
The generation of bioelectricity from bagasse and cane
trash/wastes has not been discussed in detail. There is a
huge potential, not only to generate bioelectricity in order to
improve net energy balances and efficiency, but also to
trade-off entire GHG balances in the sugarcane systems of
Nepal. Therefore, life cycle economic and social sustainability, and the optimization of relevant sustainability indicators,
such as net energy and GHG balances and the utilization of
cane trash/wastes for electricity generation is another step
worthy of investigation.
(b) The development of life cycle case studies for sustainability
assessment, and the optimization of sugarcane-based commercial energy sources (i.e. bioelectricity and bioethanol) are
important for many least developed countries (LDCs). In
this regard, a similar case study in one of the African LDCs
would be interesting to investigate. After the compilation of
field data from the production chain of bioethanol in different LDCs, the modelling of climate, energy, land use, environmental performance, and the consumption of other natural resources, such as water, could be carried out.
(c) Last but not the least, in order to allow a comparative analysis of the sustainability assessment of bioethanol production
from sugarcane feedstock, methodological coherence and
unification should be established and benchmarked globally
in the context of the evaluation of sustainable bioenergy systems for product certification, and international trade from
the life cycle perspective. Therefore, the evaluation of sugarcane bioethanol, with methodological improvements towards international common ground, is the next step of this
research work.
59
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