WNA Report
Comparison of Lifecycle
Greenhouse Gas Emissions
of Various Electricity
Generation Sources
1
Contents
1. Introduction 2
2. Scope and Objectives 2-4
3. Methodology 5
4. Summary of Assessment Findings 6-8
5. Conclusions 9
6. Acknowledgement 9
7. References 9-10
2
1
Introduction
The emission of greenhouse gases (GHGs) and their implications to climate change have sparked global
interest in understanding the relative contribution of the electrical generation industry. According to the
Intergovernmental Panel on Climate Change (IPCC), the world emits approximately 27 gigatonnes of
CO
2
e from multiple sources, with electrical production emitting 10 gigatonnes, or approximately 37% of
global emissions
i
. In addition, electricity demand is expected to increase by 43% over the next 20 years
ii
.
This substantial increase will require the construction of many new power generating facilities and offers
the opportunity to construct these new facilities in a way to limit GHG emissions.
There are many different electrical generation methods, each having advantages and disadvantages with
respect to operational cost, environmental impact, and other factors. In relation to GHG emissions, each
generation method produces GHGs in varying quantities through construction, operation (including fuel
supply activities), and decommissioning. Some generation methods such as coal fired power plants release
the majority of GHGs during operation. Others, such as wind power and nuclear power, release the
majority of emissions during construction and decommissioning. Accounting for emissions from all phases
of the project (construction, operation, and decommissioning) is called a lifecycle approach. Normalizing
the lifecycle emissions with electrical generation allows for a fair comparison of the different generation
methods on a per gigawatt-hour basis. The lower the value, the less GHG emissions are emitted.
2
Scope and Objectives
The objective of this report is to provide a comparison of the lifecycle GHG emissions of different
electricity generation facilities. The fuel types included in this report are:
• Nuclear;
• Coal;
• Natural Gas;
• Oil;
• Solar Photovoltaic;
• Biomass;
• Hydroelectric; and
• Wind.
Table 1 lists all studies utilized for the report, the organization that completed it, and the date the report
was published.
Carbon Capture and Sequestration (CCS) is often cited as a technology that could dramatically reduce
carbon emissions from coal fired power plants. Although this technology appears quite promising, it is
currently in early developmental stages and does not have widespread commercial application. Therefore,
the lifecycle GHG emissions can not be accurately estimated and have not been included in this report.
3
Title
Year
Released
Publishing
Organization
Type of
Organization
Link
Hydropower-
Internalised Costs
and Externalised
Benefits
2001 IEA Government/
Agencies
http://www.nea.fr/globalsearch/
search.php
Greenhouse Gas
Emissions of
Electricity Chains:
Assessing the
Difference
2000 IAEA Government/
Agencies
http://www.iaea.org/Publications/
Magazines/Bulletin/Bull422/
article4.pdf
Comparison of
Energy Systems
Using Life Cycle
Assessment
2004 World Energy
Council
Government/
Agencies
http://www.worldenergy.org/
documents/lca2.pdf
Uranium Mining,
Processing and
Nuclear Energy —
Opportunities for
Australia?
2006 Australian
Government
Government/
Agencies
http://www.ansto.gov.au/__data/
assets/pdf_file/0005/38975/
Umpner_report_2006.pdf
European
Commission Staff
Working Document
2007 European
Commission
Government/
Agencies
http://ec.europa.eu/energy
GHG Emissions and
Avoidance Costs of
Nuclear, Fossil Fuels
and Renewable
2007 Öko-Institut
(Institute for
Applied Ecology)
Government/
Agencies
http://www.oeko.de
Environmental
Impacts of
PV Electricity
Generation
2006 European
Photovoltaic
Solar Energy
Conference
Universities http://www.ecn.nl/docs/library/
report/2006/rx06016.pdf
Externalities and
Energy Policy
2001 OECD Nuclear
Energy Agency
Government/
Agencies
http://www.nea.fr/html/
ndd/reports/2002/nea3676-
externalities.pdf
Greenhouse-gas
Emissions from
Solar Electric and
Nuclear Power
2007 Columbia
University
Universities http://www.ecquologia.it/sito/
energie/LCA_PV_nuc.pdf
Life-Cycle
Assessment
of Electricity
Generation Systems
and Applications
for Climate Change
Policy Analysis
2002 University of
Wisconsin
Universities http://fti.neep.wisc.edu/pdf/
fdm1181.pdf
Nuclear Power -
Greenhouse Gas
Emissions and Risks
a Comparative Life
Cycle Analysis
2007 California Energy
Commission
Nuclear Issues
Workshop
Government/
Agencies
http://www.energy.
ca.gov/2007_energypolicy/
documents/2007-06-25+28_
workshop/presentations/panel_4/
Vasilis_Fthenakis_Nuclear_Power-
Greenhouse_Gas_Emission_Life_
Cycle_Analysis.pdf
4
Title
Year
Released
Publishing
Organization
Type of
Organization
Link
Quantifying
the Life-Cycle
Environmental
Profile of
Photovoltaics and
Comparisons with
Other Electricity-
Generating
Technologies
2006 National PV
EH&S Research
Center
Industry/
Associations
http://www.bnl.gov/pv/files/pdf/
abs_195.pdf
ExternE National
Implementation
Germany
1997 IER Universities http://www.regie-energie.
qc.ca/audiences/3526-04/
MemoiresParticip3526/Memoire_
CCVK_75_ExternE_Germany.pdf
Climate Declaration
for Electricity
from Wind Power
(ENEL)
2008 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
Documents/decl/CD66.pdf
Climate Declaration
for Electricity from
Nuclear Power
(Axpo)
2008 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
Documents/decl/CD144.pdf
Climate Declaration
for Electricity from
Nuclear Power
(Vattenfall)
2007 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
Documents/decl/CD21.pdf
Climate
Declaration:
Product: 1kWh
net Electricity
from Wind Power
(Vattenfall)
2010 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
PageFiles/383/epdc115e.pdf
Climate Declaration
for Electricity
from Hydropower
(Vattenfall)
2008 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
Documents/decl/CD88.pdf
Climate Declaration
for Electricity
and District Heat
from Danish Coal
Fired CHP Units
(Vattenfall)
2008 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.klimatdeklaration.se/
Documents/decl/CD152.pdf
EDP Otelfinger
Kompogas Biomass
(Axpo)
2008 Swedish
Environmental
Management
Council
Industry/
Associations
http://www.environdec.com/reg/
epd176.pdf
EDP of Electricity
from Torness
Nuclear Power
Station
(British Energy)
2009 British Energy/
AEA
Industry/
Associations
http://www.british-energy.com/
documents/Torness_EPD_
Report_Final.pdf
5
Methodology
This report is a secondary research compilation of literature in which lifecycle GHG emissions associated
with electricity generation have been accounted for. To be included within this compilation, the source
needed to meet the following requirements:
• Be from a credible source. Studies published by governments and universities were sought out,
and industry publications used when independently verified.
• Clearly define the term “lifecycle” used in the assessment. Although the definition of lifecycle can
vary, to be considered credible, the source needed to clearly state what definition was being used.
• Include nuclear power generation and at least one other electricity generation method. This would
ensure that the comparison to nuclear was relevant.
• Express GHG emissions as a function of electricity production (e.g. kg CO
2
e/kWh or equivalent).
This would ensure that the comparison across electricity generation was relevant.
Figure 1 summarizes the number of literature sources evaluated for each generation method.
3
*iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii, xviii, xix, xx, xxi, xxii, xxiii
16
14
12
10
8
6
4
2
Number of Sources
Oil
Lignite
Coal
Solar PV
Nuclear
Natural Gas
Biomass
Hydroelectric
Wind
6
10
5
12
13
5
14
7
11
Figure 1: Number of Sources for each Generation Type
6
4
Summary of Assessment Findings
Lifecycle GHG emissions for the different electricity generation methods are provided in Table 2 and shown
graphically in Figure 2. Although the relative magnitude of GHG emissions between different generation
methods is consistent throughout the various studies, the absolute emission intensity fluctuates. This is
due to the differences in the scope of the studies.
The most prominent factor influencing the results was the selection of facilities included in the study.
Emission rates from power generation plants are unique to the individual facility and have site-specific and
region-specific factors influencing emission rates. For example, enrichment of nuclear fuel by gaseous
diffusion has a higher electrical load, and therefore, lifecycle emissions are typically higher than those
associated with centrifuge enrichment. However, emissions can vary even between enrichment facilities
dependant upon local electrical supply (i.e. is electricity provided by coal fired power plants or a low
carbon source).
Another factor influencing results was the definition of lifecycle. For example, some studies included waste
management and treatment in the scope, while some excluded waste. When the study was completed, also
led to a broader range in results, and was most prevalent for solar power. This is assumed to be primarily
due to the rapid advancement of solar photovoltaic panels over the past decade. As the technology and
manufacturing processes become more efficient, the lifecycle emissions of solar photovoltaic panels will
continue to decrease. This is evident in the older studies estimating solar photovoltaic lifecycle emission
to be comparable to fossil fuel generation methods, while recent studies being more comparable to other
forms of renewable energy. The range between the studies is illustrated within the figure.
Technology
Mean Low High
tonnes CO
2
e/GWh
Lignite 1,054 790 1,372
Coal 888 756 1,310
Oil 733 547 935
Natural Gas 499 362 891
Solar PV 85 13 731
Biomass 45 10 101
Nuclear 29 2 130
Hydroelectric 26 2 237
Wind 26 6 124
*iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii, xviii, xix, xx, xxi, xxii, xxiii
Table 2: Summary of Lifecycle GHG Emission Intensity
7
Coal fired power plants have the highest GHG emission intensities on a lifecycle basis. Although natural
gas, and to some degree oil, had noticeably lower GHG emissions, biomass, nuclear, hydroelectric, wind,
and solar photovoltaic all had lifecycle GHG emission intensities that are significantly lower than fossil fuel
based generation.
Nuclear power plants achieve a high degree of safety through the defence-in-depth approach where,
among other things, the plant is designed with multiple physical barriers. These additional physical
barriers are generally not built within other electrical generating systems, and as such, the greenhouse
gas emissions attributed to construction of a nuclear power plant are higher than emissions resulting from
construction of other generation methods. These additional emissions are accounted for in each of the
studies included in Figure 2. Even when emissions from the additional safety barriers are included, the
lifecycle emissions of nuclear energy are considerably lower than fossil fuel based generation methods.
Averaging the results of the studies places nuclear energy’s 30 tonnes CO2e/GWh emission intensity at
7% of the emission intensity of natural gas, and only 3% of the emission intensity of coal fired power
plants. In addition, the lifecycle GHG emission intensity of nuclear power generation is consistent with
renewable energy sources including biomass, hydroelectric and wind.
Figure 3 illustrates source evaluation data by study group. Using linear regression, the coefficient of
correlation between industry and university sources was 0.98, between industry and government was
0.98, and between university and government was 0.95. This shows that emission intensities are consistent
regardless of the data source.
Figure 4 illustrates averaged source data subdivided into those organizations specializing in nuclear
energy and those groups specialising in other energy options and those addressing energy in general.
*iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii, xviii, xix, xx, xxi, xxii, xxiii
Figure 2: Lifecycle GHG Emissions Intensity of Electricity Generation Methods
1600
1400
1200
1000
800
600
400
200
GHG Emissions
(Tonnes CO
2
e/GWh)
Oil
Lignite
Coal
Solar PV
Nuclear
Natural Gas
Biomass
Hydroelectric
Wind
Average Emissions Intensity
1069
888
735
500
85
45
28
26
Range Between Studies
26
8
Figure 3: Comparison of LCA Results Between Sources
*iii, iv, v, vi, vii, viii, ix, x, xi, xii, xiii, xiv, xv, xvi, xvii, xviii, xix, xx, xxi, xxii, xxiii
1200
1000
800
600
400
200
GHG Emissions
(Tonnes CO
2
e/GWh)
Oil
Lignite
Coal
Solar PV
Nuclear
Natural Gas
Biomass
Hydroelectric
Wind
115
42
31
501
416
580
901
895
841
1074
1047
935
33
70
39
25
13
29
5
36
10
18
Universities
Government/Agencies Industry/Associations
685
The main difference between the two sets of results is that on average the nuclear specialist studies tend to
have somewhat lower LCA GHG emissions, particularly for fossil fuels. However, the overall conclusions
with regards the comparative emissions of fossil fuels, nuclear and renewables are consistent.
Figure 4: Comparison of LCA Results between nuclear specialists and other sources
1200
1000
800
600
400
200
gCO
2
/kwh
Oil
Lignite
Coal
Solar PV
Nuclear
Natural Gas
Biomass
Hydroelectric
Wind
837
818
547
413
75
10
15
20
12
1133
921
731
506
97
52
30
27 30
Nuclear Specialist Average
Others Average
9
References
i
International Energy Agency. Energy Technology Perspectives [Online]. 2008 [cited August 1, 2010]; Available from;
http://www.iea.org/w/bookshop/add.aspx?id=330
ii
International Atomic Energy Agency, World Energy Outlook 2009 – GLOBAL ENERGY TRENDS TO 2030 [Online], 2009
[cited August 1, 2010]; Available from http://www.iea.org/W/bookshop/add.aspx?id=388
iii
International Energy Agency. Hydropower-Internalised Costs and Externalised Benefits [Online]. 2001 [cited August 1,
2010]; Available from http://www.nea.fr/globalsearch/search.php
iv
International Atomic Energy Agency. Greenhouse Gas Emissions of Electricity Chains: Assessing the Difference [Online].
2001 [cited August 1, 2010]; Available from http://www.iaea.org/Publications/Magazines/Bulletin/Bull422/article4.pdf
v
World Energy Council. Comparison of Energy Systems Using Life Cycle Assessment [Online]. 2004 [cited August 1, 2010];
Available from http://www.worldenergy.org/documents/lca2.pdf
vi
Fritsche, U. et al. Treibhausgasemissionen und Vermeidungskosten der nuklearen, fossilen und erneuerbaren Strombereitstellung
– Arbeitspapier (Greenhouse gas emissions and avoidance costs for nuclear, fossil and renewable power production–working
paper) [Online]. 2007 [cited August 1, 2010]; Available from http://www.oeko.de
vii
Australian Government. Uranium Mining, Processing and Nuclear Energy -Opportunities for Australia? [Online]. 2006 [cited
August 1, 2010]; Available from http://www.ansto.gov.au/__data/assets/pdf_file/0005/38975/Umpner_report_2006.pdf
7
Conclusions
Based on the studies reviewed, the following observations can be made:
• Greenhouse gas emissions of nuclear power plants are among the lowest of any electricity generation
method and on a lifecycle basis are comparable to wind, hydro-electricity and biomass.
• Lifecycle emissions of natural gas generation are 15 times greater then nuclear.
• Lifecycle emissions of coal generation are 30 times greater then nuclear.
• There is strong agreement in the published studies on life cycle GHG intensities for each generation
method. However, the data demonstrates the sensitivity of lifecycle analysis to assumptions for each
electricity generation source.
• The range of results is influenced by the primary assumptions made in the lifecycle analysis. For
instance, assuming either gaseous diffusion or gas centrifuge enrichment has a bearing on the life
cycle results for nuclear.
5
Acknowledgement
WNA is grateful for the significant contribution of Jamie McIntyre, Brent Berg, Harvey Seto and Shane
Borchardt in compiling this report.
6
10
viii
Alsema, E., de Wild-Scholten, M., & Fthenakis, V. Environmental Impacts of PV Electricity Generation - A Critical
Comparison of Energy Supply Options. European Photovoltaic Solar Energy Conference [Online]. 2006 [cited August 1, 2010];
Available from http://www.ecn.nl/docs/library/report/2006/rx06016.pdf
ix
OECD Nuclear Energy Agency. Externalities and Energy Policy: The Life Cycle Analysis Approach [Online]. 2001 [cited
August 1, 2010]; Available from http://www.nea.fr/html/ndd/reports/2002/nea3676-externalities.pdf
x
Fthenakis, V., & Kim, H. C. (n.d.). Greenhouse-gas emissions from solar electric and nuclear power: A life-cycle study [Online].
2007 [cited August 1, 2010]; Available from http://www.ecquologia.it/sito/energie/LCA_PV_nuc.pdf
xi
Meier, P. Life-Cycle Assessment of Electricity Generation Systems and Applications for Climate Change Policy Analysis
[Online]. 2002 [cited August 1, 2010]; Available from http://fti.neep.wisc.edu/pdf/fdm1181.pdf
xii
Fthenakis, V. Nuclear Power-Greenhouse Gas Emissions & Risks a Comparative Life Cycle Analysis [Online]. 2007 [cited
August 1, 2010]; Available from http://www.energy.ca.gov/2007_energypolicy/documents/2007-06-25+28_workshop/
presentations/panel_4/Vasilis_Fthenakis_Nuclear_Power-Greenhouse_Gas_Emission_Life_Cycle_Analysis.pdf
xiii
European Commission Staff Working Document. 2007 [cited August 1, 2010]; Available from http://ec.europa.eu/energy
xiv
Fthenakis, V., & Kim, H. Quantifying the Life-Cycle Environmental Profile of Photovoltaics and Comparisons with Other
Electricity-Generating Technologies [Online]. 2006 [cited August 1, 2010]; Available from http://www.bnl.gov/pv/files/
pdf/abs_195.pdf
xv
ExternE National Implementation Germany [Online]. 1997 [cited August 1, 2010]; Available from
http://www.regie-energie.qc.ca/audiences/3526-04/MemoiresParticip3526/Memoire_CCVK_75_ExternE_Germany.pdf
xvi
Climate Declaration for Electricity from Wind power [Online]. [2008] [cited August 1, 2010]; Available from
http://www.klimatdeklaration.se/Documents/decl/CD66.pdf
xvii
Climate Declaration for Electricity from Nuclear Power [Online], [2007] [cited August 1, 2010]; Available from
http://www.klimatdeklaration.se/Documents/decl/CD144.pdf
xviii
Climate Declaration for Electricity from Nuclear Power [Online]. [2007] [cited August 1, 2010]; Available from
http://www.klimatdeklaration.se/Documents/decl/CD21.pdf
xix
Climate Declaration: Product: 1kWh net Electricity from Wind Power [Online]. [2010] [cited August 1, 2010]; Available from
http://www.klimatdeklaration.se/PageFiles/383/epdc115e.pdf
xx
Climate Declaration for Electricity from Hydropower [Online]. [2008] [cited August 1, 2010]; Available from
http://www.klimatdeklaration.se/Documents/decl/CD88.pdf
xxi
Climate Declaration for Electricity and District Heat from Danish Coal Fired CHP Units [Online]. [2008] [cited August 1,
2010]; Available from http://www.klimatdeklaration.se/Documents/decl/CD152.pdf
xxii
EDP Otelfinger Kompogas Biomass [Online]. [2008] [cited August 1, 2010]; Available from http://www.environdec.com/
reg/epd176.pdf
xxiii
EDP of Electricity from Torness Nuclear Power Station [Online]. [2009] [cited November 13, 2010]; Available from
http://www.british-energy.com/documents/Torness_EPD_Report_Final.pdf
July 2011
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The World Nuclear Association is the international private-sector
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supporting the people, technology, and enterprises
that comprise the global nuclear energy industry.
WNA members include
the full range of enterprises involved in producing nuclear
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– from uranium miners to equipment suppliers to generators of
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With a secretariat headquartered in London, the
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