Life cycle analysis of electricity generation systems with implications on climate change policy

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LIFECYCLEANALYSISOFELECTRICITYGENERATION
SYSTEMSWITHIMPLICATIONSONCLIMATE
CHANGEPOLICY
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NIANJIALIANGVICTOR
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NATIONALUNIVERSITYOFSINGAPORE
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2014
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LIFECYCLEANALYSISOFELECTRICITYGENERATION
SYSTEMSWITHIMPLICATIONSONCLIMATE

CHANGEPOLICY
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NIANJIALIANGVICTOR
B.Eng.(Hons.),NUS
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ATHESISSUBMITTED
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FORTHEDEGREEOFDOCTOROFPHILOSOPHY
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DEPARTMENTOFMECHANICALENGINEERING
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NATIONALUNIVERSITYOFSINGAPORE
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2014
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Declaration

I hereby declare that,this thesis
is
my original work and
it
has
been written by
me
in
its entirety.
I have duly acknowledged all the sources
of
information which have been
used in the thesis.
This thesis
has
also
not
been submitted
for
any degree in any university
previously.
Nian Jialiang Victor
3 January
2014
i
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Acknowledgement

Iwouldlike togratefullyandsincerely thankmythesissupervisor,Professor
Chou Siaw Kiang for his guidance, understanding, and patience during my

graduatestudiesattheNationalUniversityofSingapore.Hismentorshipwas
paramount in providing a well‐roundedexperience consistent mylong‐term
career goals. He encouraged me to not only grow as an engineer and an
academicresearcher,butalsoasaninstructorandanindependentthinker.I
amgratefulforhisconfidenceinmydevelopmentofmyindividualityandself‐
sufficiencybybeingallowedtoworkwithsuchindependence.Foreverything
you’vedoneforme,ProfessorChou,Ithankyou.Iwouldalsoliketothankthe
Department of Mechanical Engineering, especially all members inmy thesis
committeefortheiradviceinshapingthefocusofmyresearch.

IwouldalsoliketothankDr.JohnBaulyforhisguidanceingettingmygraduate
careerstartedontherightfootandprovidingmegenerouslywithhisexpert
knowledgevaluabletomyresearch.Iamgratefulforhisgeneroussharingof
hisvastexperiencesinnuclearengineering.Despitehisbusyscheduleandthe
long distance between Singapore and Zurich, his valuable comments and
advice had alwaysbeen reaching me
 in atimely manner. Working withhim
grantedmewiththe uniqueopportunitytogainawiderbreadthofresearch
experiences.

IwouldliketothanktheEnergyStudiesInstituteforgivingmetheopportunity
toparticipateinimportantresearchprojects.Iwashonouredtobeawarded 
with a research
scholarship top‐up from the institute for the project on an
energyeconomymodeloftheSingapore’selectricitysector.

Finally,andmostimportantly,Iwouldliketothankmyfamily,especiallymy
parents,fortheirsupport,encouragement,quietpatienceandunfailinglove.I
am grateful for their faith in me and allowing me to be as ambitious as I
ii

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wanted.ItwasundertheirwatchfuleyethatIgainedso much drive and an
abilitytotacklechallengesheadon.
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iii
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TableofContents
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Summary iv
ListofFigures vi
ListofTables viii
ListofAbbreviations ix
ListofSymbols xi
1 Introduction 1
2 LiteratureReview 13
3 DevelopmentoftheMethodology 27
3.1 Genericpowergenerationsystemdefinition 27
3.2 Levelledsystemstructureandassociatedboundaries 40
3.3 KayaIdentityanddecomposition 53
4 CaseStudyonaReferenceLightWaterReactor 107
4.1 Referenceglobaluraniumsupplychain 107
4.2 Uraniumfuelcyclecalculation 109
4.3 ProcessChainAnalysisfortheLWR 116
4.4 Lifecycleenergyandcarbonemissionanalysis 134
4.5 Furtheranalysis 147
5 CaseStudyonFutureSmallMediumReactors 169
5.1 Thestateoffissionpowerreactordevelopment 169
5.2 ReactortechnologyroadmaptowardsGenerationIV 181

5.3 TheprospectsoftheSMRs 190
5.4 Evolutiontowards“SmarterEnergy”future 207
6 Discussions 217
6.1 TechnicalBenefits 217
6.2 PolicyBenefits 221
6.3 Limitations 223
7 ConcludingRemarks 226 
References 231
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iv
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Summary
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Given the urgency to mitigate the warming climate caused by excess
anthropogenic carbon emissions, decarbonizing the global energy system
rankedas oneof the toppriorities.In evaluating thealternativelow carbon
technologies,lifecycleanalysis(LCA)emergedstronglyasamodellingtoolfor
supporting the decision making process. An
LCA focusing on energy
consumption and carbon emissions can provide insights on climate change
policy.Overthedecades,twodominant approacheswereestablishedinthe
LCAliterature,namelytheInput‐OutputAnalysis(IOA),andtheProcessChain
Analysis(PCA)approaches.

TheIOAisaneconomicdriventop‐downapproachthat
considersaggregated
flowsbetweeneconomicsectors.ThePCAisabottom‐upa pproachthatuses
engineering and process‐specific data. PCA generally yields more accurate
results, but it is a time consuming exercise. Thus, a PCA exercise is usually
simplified by applying “cut‐off” criteria to exclude less relevant processes,

leadingtowardspotentialunder‐estimationoftheimpact.Ontheotherhand,
theresultsfromIOAaremorecompleteandlesscasedependent,buttheyare
also less precise. There are also transparency issues due to the lack of
granularityattheprocesslevel.

From a quick scan, we detected a
 large dispersion on the life cycle carbon
emissionfactorsofelectricitygenerationsystem,nuclearpowerinparticular.
v
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Basedonourliteraturereview,therewasalackofstandardizedmethodology
in the PCA approach for benchmarking. In response, we proposed a
methodologytostreamline theformulationofthelifecycleenergysystem.The
methodology,developedbasedonthefirstprinciple,cangivecleardepiction
on the elementary mechanisms of the input‐output interactions across the
systemboundaries.Theresultingsystemboundariescanfacilitatetheuseof
KayaIdentityandthedecompositionconcepttoobjectivelyestablishthe“cut‐
off”criteriaforanLCA‐PCAexercise.

Twocasestudiesweredevelopedwithoneonareferencelargesizereactor
systemandtheotheronaSmallandMediumReactor(SMR)system.Fromthe
case study results, the methodology was capable of estimating with good
confidence the life cycle carbon emission factor of existing electricity
generationsystems.Itwasalsocapableofprojectingthelifecycleenergyinput
andcarbonemissionsoffutureelectricitygenerationtechnologies,suchasan
advanced SMR system. Moreover, the methodology was also capable of
analysing the influence of key design parameters on the life cycle carbon
emissions of the system. These capabilities can provide insights directly
relevantforenergysystemplanningandclimatechangepolicymaking.


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vi
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ListofFigures
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Figure1‐1The“450Scenario”developedbytheIEA 3
Figure1‐2GeneralframeworkofanLCAonfissionpowergeneration 6
Figure1‐3Lifecyclecarbonemissionsoffissionpowergenerationreportedin
theliterature(logarithmplot) 7
Figure2‐1CriteriaontheevaluationofLCAmethodologies 14
Figure3‐1Schematicofaheatengine 28
Figure3‐2Schematicofsteamelectricitygeneration 29
Figure3‐3Schematicofthegenericelectricitygenerationsystem 30
Figure3‐4Genericelectricitygenerationsystemwithrepresentationson
environmentalimpact 31

Figure3‐5Powergenerationandupstreamsystems 32
Figure3‐6Schematicofabroaderfuelfabricationsystem 34
Figure3‐7Extendedenergyinputdefinitionforpowergenerationsystem 35
Figure3‐8Formationoflifecycleelectricitygenerationsystemviasystem
merging 36

Figure3‐9Completerepresentationofthelifecycleelectricitygeneration
system 37
Figure3‐10Genericlifecycleelectricitygenerationsystem 37
Figure3‐11Generic“LCAMainSystem”definitionforelectricitygenerationin
thePCAapproach 38
Figure3‐12Boundariesbetweenthetechnologicalsystemandits
surroundings 45

Figure3‐13Boundariesbetweenthe“LCAMainSystem”andthe“LCASub‐
systems” 45
Figure3‐14Expandedviewoflevelledsystemstructure 49
Figure3‐15DefiningthecarbonemissionstreamswithC
Int
andC
Ext
 55
Figure3‐16Simplifiedmulti‐processsystemrepresentation 58
Figure3‐17SchematicfordecomposingatLevel1‐“EnergyInput”side 63
Figure3‐18SchematicfordecomposingatLevel2‐“EnergyInput”side 71
Figure3‐19SchematicfordecomposingatLevel1‐“Non‐EnergyInput”side
82

Figure3‐20SchematicfordecomposingatLevel2‐“Non‐EnergyInput”side
85
Figure4‐1Globaluraniumsupplychainforthecasestudy 109
Figure4‐2Summaryofuraniumfuelcyclecalculationresults 116
Figure4‐3Schematicoftheuraniumminingandmilling“Process” 118
Figure4‐4Schematicofuraniumconversion“Process” 120
Figure4‐5Schematicofuraniumenrichment“Process”(Scenario1) 122
Figure4‐6Schematicofuraniumenrichment“Process”(Scenario2) 123
Figure4‐7Schematicofuraniumenrichment“Process”(Scenario3) 123
Figure4‐8Schematicoffuelfabrication“Process” 126
Figure4‐9Schematicofpowergeneration“Process” 129
Figure4‐10SchematicofSFinterimstorage“Process” 131
Figure4‐11Schematicofspentfueldisposal“Process” 133

vii
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Figure4‐12Benchmarkingthecasestudyresultsagainstthemedianof
publishedLCAresults 142
Figure4‐13BenchmarkingthecasestudyresultsforLevel0againstthe
medianofpublishedLCAresults 143
Figure4‐14Benchmarkingthecasestudyresultsagainsttheaverageof
publishedvalues 144
Figure4‐15BenchmarkingthecasestudyresultsforLevel0againstthe
averageofpublishedvalues 145
Figure4‐16Distributionof“ProcessEnergyInput” 149
Figure4‐17Shareof“ProcessEnergyInput” 150
Figure4‐18Distributionofupstream“ProcessEnergyInput” 151
Figure4‐19Distributionof“Process”carbonemissions 153
Figure4‐20Shareof“Process”carbonemissions 154
Figure4‐21Distributionofupstream“Process”carbonemissions 155
Figure4‐22Influenceofuraniumoregradetothelifecyclecarbonemission
factorofthereferenceLWRsystem 158
Figure4‐23Typicalinitialloadingmapforareactorcore 160
Figure4‐24Impactofenrichmentconcentrationtothelifecycleemission
factor 162
Figure4‐25Scenariodependenttrajectoriesofemissionfactors 163
Figure4‐26Influenceof
235
UConcentrationinScenario1 164
Figure4‐27Influenceof
235
UConcentrationinScenario2 166
Figure4‐28Influenceof
235
UConcentrationinScenario3 168
Figure5‐1Graphite“pebble”forPebbleBedReactor 171

Figure5‐2OlkiluotonuclearpowerstationUnit3(EPRunit) 174
Figure5‐3LoviisanuclearpowerstationwithtwounitsofVVER‐440 174
Figure5‐4QinshanCANDUnuclearpowerstation 175
Figure5‐5Shikanuclearpowerstation(BWRandABWR) 176
Figure5‐6Leningradnuclearpowerplant(RMBKandVVERreactors) 177
Figure5‐7Monjunuclearpowerstation(sodiumcooledLMFBR) 179
Figure5‐8TornessAGRpowerstation,Scotland 180
Figure5‐9Roadmapforfissionpowerreactors 183
Figure5‐10Theprospectoffuturereactorlicensing 184
Figure5‐11Benchmarkinglifecyclecarbonemissionfactors 192
Figure5‐12BenchmarkingthelifecyclecarbonemissionfactoroftheSMRin
thetechnologyconservativescenario 195
Figure5‐13BenchmarkingthelifecyclecarbonemissionfactoroftheSMRin
thetechnologyoptimisticscenario 197
Figure5‐14Influenceofuraniumoregradetothelifecyclecarbonemission
factoroftheconceptualizedSMR 199
Figure5‐15LCOEsofalternativepowergenerationtechnologies 201
Figure5‐16Capitalcostsofalternativepowergenerationtechnologies 202
Figure5‐17Capitalcostsofalternativepowergenerationtechnologies
includingSMR 203

Figure5‐18LCOEsofalternativepowergenerationtechnologiesincluding
SMR 204



viii

ListofTables


Table2‐1SummaryofsignificantmilestonesinLCAdevelopment 25
Table4‐1OperatingconditionsofthereferenceLWRsysteminSingapore110
Table4‐2SummaryofSWUcalculation 114
Table4‐3Miningandmilling“Process”inputs 119
Table4‐4Conversion“Process”inputs 121
Table4‐5Enrichment“Process”inputs‐Scenario1 124
Table4‐6Enrichment“Process”inputs‐Scenario2 124
Table4‐7Enrichment“Process”inputs‐Scenario3 125
Table4‐8Fuelfabrication“ProcessEnergyInput”‐Scenario1 127
Table4‐9Fuelfabrication“ProcessEnergyInput”‐Scenario2 127
Table4‐10Fuelfabrication“ProcessEnergyInput”‐Scenario3 127
Table4‐11Fuelfabrication“ProcessNon‐EnergyInput”‐allscenarios 128
Table4‐12Powergeneration“Process”inputs 129
Table4‐13SFinterimstorage“Process”inputs 131
Table4‐14Spentfueldisposal“Process”inputs 133
Table4‐15Carbonemissionfactorsofelectricity 134
Table4‐16Carbonemissionfactorsoffuels 135
Table4‐17Carbonemissionfactorsofpowerplantmaintenanceactivities135
Table4‐18EnergyandcarbonemissionanalysisforScenario1 135
Table4‐19EnergyandcarbonemissionanalysisforScenario2 136
Table4‐20EnergyandcarbonemissionanalysisforScenario3 137
Table4‐21Carbonemissionfactorsof“Non‐EnergyInput” 139
Table4‐22CasestudyresultsforthereferenceLWRsystem 140
Table4‐23Lifecyclecarbonemissionsonfissionpowerreportedglobally.140
Table4‐24Summaryofresultsforenergyandcarbonemissionanalysis 147
Table4‐25Summaryof“ProcessEnergyInput”inphysicalunit 149
Table4‐26Summaryof“ProcessEnergyInput”inpercentage 150
Table4‐27Summaryof“Process”carbonemissionsinphysicalunit 152
Table4‐28Summaryof“Process”carbonemissionsinpercentage 154
Table4‐29Initial

235
Uenrichmentvs.averageassemblyburn‐upforLeibstadt
LWR 161

Table5‐1SummaryofcurrentSMRdesigns 186
Table5‐2SMRoperatingconditions–technologyconservativescenario 193
Table5‐3SummaryofcasestudyresultsfortheconceptualizedSMRinthe
technologyconservativescenario 194
Table5‐4SMRoperatingconditions–technologyoptimisticscenario 196
Table5‐5SummaryofcasestudyresultsfortheconceptualizedSMRinthe
technologyoptimisticscenario 196
Table5‐6OvernightcostandtheLCOEoftheconceptualizedSMRdesign.203
Table5‐7Benchmarkingthekeycharacteristicsofalternativepower
generationtechnologies 211



ix

ListofAbbreviations

ABWR Advancedboilingwaterreactor
AGR Advancedgas‐cooledreactor
AHTR Advancedhightemperaturereactor
ASEAN AssociationofSoutheastAsianNations
BWR Boilingwaterreactor
CANDU CanadaDeuteriumUranium
CCGT Combinedcyclegasturbine
CRIEPI CentralResearchInstituteofElectricPowerIndustry
DEPT Dimensionlessenergypaybacktime

EDF Electricityde
France
EJ Exajoule
EPR EuropeanPressurizedReactor
EPT Energypaybacktime
ESBWR Economicallysimplifiedboilingwaterreactor
FBR Fastbreederreactor
FNR Fastneutronreactor
GCR Gascooledreactor
GDP Grossdomesticproduct
GHG Greenhousegas
GIF GenerationIVInternationalForum
GJ Gigajoule
GFR Gas‐cooledFastReactor
GMR Graphitemoderated
reactor
GWD GigawattDay(typicalunitforuraniumfuelburn‐up)
GWh Gigawatthour
HTR Hightemperaturereactor
HWR Heavywaterreactor
IAEA InternationalAtomicEnergyAgency
IEA InternationalEnergy Agency
IR InferredResources
ISL In‐Situleaching
IPCC IntergovernmentalPanelonClimateChange
LCA Lifecycleanalysis
LCI Lifecycleinventory
LCOE Levellizedcostofelectricity
LFR Lead‐cooledFastReactors
LMFBR Liquidmetalfastbreederreactor

LS‐VHTR Liquidsaltveryhightemperaturereactor
LWR Lightwaterreactor
MSR Moltensaltreactor
MWD MegawattDay(typicalunitforuraniumfuelburn‐up)
MWe Megawattofelectricity
MWh Megawatthour
MWt Megawattofthermalenergy
NEA NuclearEnergyAgency

x

OCGT Opencyclegasturbine
OECD OrganizationforEconomicCooperationandDevelopment
OMR Organicallymoderatedreactor
O&M Operationandmaintenance
PHWR Pressurizedheavywaterreactor
RPV Reactor pressurevessel
PWR Pressurizedwaterreactor
RAR Reasonableassuredresources
RBMK ReaktorBolshoyMoschnostiKanalniy(HighPowerChannel
Reactor)
R&D Researchanddevelopment
SC Supercritical
SCWR Supercriticalwatercooledreactor
SFR Sodiumcooledfastreactor
SMR SmallandMediumReactor
SWU Separativeworkunit
toe Tonneofoilequivalent
TWh Terawatthour
UNFCCC UnitedNationsFrameworkConventiononClimateChange

UNGG UraniumNaturelGraphiteGaz
USC Ultra‐supercritical
U.S.DOE UnitedStatesDepartmentofEnergy
U.S.EIA UnitedStatesEnergyInformationAdministration
U.S.NERAC UnitedStatesNuclearEnergyResearchAdvisoryCommittee
U.S.NRC UnitedStatesNuclearRegulatoryCommission
VHTR Veryhightemperaturereactor
VVER Vodo‐VodyanoiEnergeticheskyReactor
WNA WorldNuclearAssociation
WWER Water‐WaterEnergeticReactor



xi

ListofSymbols



 :then
th
processofthe“LCASub‐system”onthe“EnergyInput”
side


 :“product”of“Process”






 :then
th
processofthe“LCASub‐system”onthe“Non‐Energy
Input”side


 :“product”of“Process”


 :carbon(GHG)emissions


 :carbonemissionsduetoEnergyInput


 :extrinsicemissionof“Process”input



:carbonemissionsfromfuelfabrication


 :intrinsicemissionof“Process”input


 :carbonemissionsfromthe“Fuel”


 :lifecyclecarbonemissionsfromthe“LCAMainSystem”



 :carbonemissionsfromthemining


 :carbonemissionsdueto“Non‐EnergyInput”



:carbonemissionsfromthepowergeneration



:carbonemissionsofasystem


 :thecarboncostatyear“”


 :thedecommissioningcostatyear“”
 :energyintensityofproductfromalifecycle“Process”



:theamountofenergyorheatreleasedfromfuel(primary
energy)



:energyinputtothefuelfabricationsystem




:energylossofthefuelfabricationsystem


 :energyinputtotheminingsystem


 :energylossoftheminingsystem

,,

:“EnergyInput”toeach“Process”ofthe“LCAMainSystem”or
“Sub‐system”


 :“EnergyInput”toasystem


 :energylossesofasystem


 :energyoutputfromasystem



:energyinputtothefuelfabricationprocess



 :energyinputtotheminingsystem


 :energylossoftheminingsystem



:energyinputtothepowergenerationprocess


 :electricitygeneratedatyear“”


 :fragmentsfromthefissionprocess
 :thesubstancerequiredtoproducethermalenergy


 :thefuelcostattime(year)“”
 :heatvalueofreactorfuel


 :theinvestmentcostattime(year)“”
 :conversionfactorforspentfuelassembly(kgperunitofspent 
fuel)

xii

 :massofdifferentformsoffuel(denotedbyeachrespective
subscript)




:feedmass



:massofwastes(residues)fromthefuelfabricationprocess



:massoffuelforproducingthermalenergy



:productmass



:wastes(residues)fromthepowergenerationprocess(quasi‐
heat‐enginedefinition)


 :tailmass


 :GHGemissionsfrompowergeneration


 :wastes(residues)producedfrompowergeneration



 :wastes(residue)factor(genericdefinition)


 :“Non‐EnergyInput”(e.g.powerplantfacilities,pumps,
materials,etc.)topowergeneration

,,

:“Non‐EnergyInput”toeach“Process”ofthe“LCAMainSystem”
or“Sub‐system”
 :intensityof“Non‐EnergyInput”consumptionof“product”ina
“Process”


 :intensityof“Non‐EnergyInput”requiredto“produce”

by
type
&

 :theoperationsandmaintenancecostattime(year)“”


 :generatingcapacityofthemodelplant


 :“product”ofthen
th
“Process”ofthe“LCAMainSystem”



 :themagnitudeofheattransferbetweenthecyclicdeviceand
thehigh‐temperaturemediumattemperature




 :themagnitudeofheattransferbetweenthecyclicdeviceand
thelow‐temperaturemediumattemperature


 :thermalenergy
 :discountrate
 :separativeworkfunction
 :lifetimeofthemodelplant


 :temperatureofthehightemperaturemedium


 :temperatureofthelowtemperaturemedium
 :time(year)




 :valuefunctionbasedontheenrichmentvalues
 :numberofneutrons


,

:networkoutput


 :protonnumberoftheatomicfragmentafterfissionprocess



:feedassay



:productassay


 :tailassay



:
235
Uenrichmentconcentration



:natural
235
Uconcentration




:uraniumoregrade
 :feed‐to‐productratio
 :energypaybacktime



:thermalefficiencyofthepowergenerationtechnology

xiii




:systemenergyefficiency
 :dimensionlessenergypaybacktime

:loadingfactor


1

1 Introduction

Global warming caused by anthropogenic carbon emissions has received
increasingattentionoverthedecades[1].Thereisastrongscientific consensus
thatcontinuedrisingtrendofglobalwarmingwillleadtocatastrophicclimate
change, threatening life of millions [2]. According to the ADB [3], climate
changewillhavesevereadverse

effectsonthesustainabledevelopmentand
poverty eradication efforts globally and particularly to the Southeast Asian
region. First, a large population (about 563 million people) lives along the
coastlines,measuring about 173,251 kilometres long. Thesepopulationsare
highly vulnerable to sea level rises. Second, even though rapid economic
growthandstructural
transformationbroughtmillionsoutofextremepoverty,
therewerestillabout93million(18.8%)livinginextremepovertyasof2005.
Third, agriculture accounted for about 43% of the total employment in
Southeast Asia and contributed about 11% GDP in 2006. The increase in
extremeweatherevents(suchasdroughts,floods,andtropicalcyclones,and
warming),andforestfiresduetoclimatechangeseriouslythreatentheexport
of agricultural produce. Lastly, increases in frequency and intensity of heat
waves,droughts,floods,andtropicalcycloneswillleadtomorefrequentand
extensivedamagetopropertiesandhumanlives.Itisthereforeimportantto
takeonurgentactionindecarbonizingourenergysystems.

One of the typical approaches in identifying the means of reducing carbon
emissions is energy systems modelling. Under the broad family of energy

2

systemmodellingframeworks,thereisalargepoolofmethodologiesandtools
focusingontheassessmentofenvironmentalimpacts,reportedbyFinnveden
[4]. By examining the pool of methodologies, life cycle analysis (LCA) is the
most relevant methodology for quantifying major potential environmental
impacts related to the product or service. In this case, the environmental
impactsrefertocarbonemissions,whichcauseglobalwarming.

TheinterestinLCAexperiencedrapidgrowthsincetheearly1990s.Initially,

LCAswereappliedforproducts[5,6]asadecisionsupporttoolforselection
among different alternatives. In the early development, LCA received both
highexpectationandvariedcriticisms,asseeninUdodeHaes[7],Ayres[8],
Ehrenfeld[9],KrozerandViz[10],andFinnveden[11].Theseexpectationsand
criticisms stimulated strong development efforts globally. Over the years,
international standards, ISO14040 [12] on principles and framework, and 
ISO14044 [13] on requirements and guidelines were established. These
standardswerecomplementedbyoperationalguides,suchasGuinée[14],and
textbooks,suchasWenzelandothers[15],andBaumannandTillman[16].

Over the decades, LCA has been progressively applied to energy producing
systems, especially power generation [17]. From 1973 to 2011, the global
energy production  increased from 6,129 TWh to 22,202 TWh at an average
annualgrowthrateof3.5%[18].In2010,powergenerationwasaccountable
for 41% of carbon emissions with 67.8% of the world electricity production
from fossil fired power plants [19]. Thus, it is important to identify suitable

3

powergenerationsystemstoreducethe carbon emissions by means ofLCA
studies.Giventhestrategicimportanceoffissionpowerinaddressingenergy
securityandreducingcarbonemissionsasdiscussedin[20,21],itbecameone
ofthepopulartargetsforLCAstudies[22].Inthe“450Scenario”developedby
the International Energy Agency (IEA), fission power was expected to
contribute to 6% of the carbon emissions reductions from the Business‐As‐
Usual(BAU)scenario(Figure1‐1drawnbasedontheinformationfrom[23]).


Figure1‐1The“450Scenario”developedbytheIEA


According to Turconi [17], therewere broadlyfour phasesin conductingan
LCA:1)goalandscopedefinition,2)inventoryanalysis,3)impactassessment,
and4)interpretation.Althoughtherewasaregulatoryframeworkdefinedin
ISO14040andISO14044,theguidelinesprovidedinthecurrentISOstandards
for conducting an LCA study allowed for flexibility in interpreting key
methodologicalissues[24].Suchflexibilityhasledtosubjectiveapproachesin
the formulation of an LCA methodology, which may produce incompatible
resultswithotherLCAstudiesofidenticalgoalsandscope.Intheabsenceofa

4

standardized approach, it was difficult to benchmark the LCA results from
differentmethodologies.

Ingeneral,therearebroadlytwoapproachesintheLCAliterature,theProcess
ChainAnalysis(PCA)andtheInput‐OutputAnalysis(IOA).PCAisabottom‐up
approachthatusesengineeringandprocess‐specificdata.Ideally,thesedata
areobtaineddirectlyfromtheactualplantsinthesupplychain.PCAgenerally
yields more accurate results, but it is a time consuming exercise [25]. Very
often,aPCAexerciseissimplifiedbyapplying“cut‐off”criteriatoexcludeless
relevantprocesses,leadingtowardspotentialunder‐estimationoftheimpact
[26]. Ontheother hand, theIOA is an economicdriventop‐down approach 
thatconsidersaggregatedflowsbetweeneconomicsectors.Itisoftenusedfor
trackingtheembodiedenergyorembodiedcarbonemissionsintrade[27,28]
withtheabilitytoconsiderthefeedbackeffectsin amulti‐regionalsetting[29].
Compared with PCA, the results from IOAare more complete and less case
dependent, but they are also less precise [30]. There are also transparency
issuesduetothelackofgranularityattheprocesslevel.

Intheliterature,therewerealsodevelopmentsonthehybridapproachesby

linkinguptheIOAandPCA,suchasBullard[31],Wilting[32],Treloar[33],Suh
[34].However,therewerenotmanystudiesusingtheseapproachesavailable
intheliterature[17].Wi edmann andothers[35]usedtwohybridapproaches
aswellasthePCAapproachtoestimatethelifecycle
carbonemissionsofwind
powerintheUK.Althoughthefinalresultsofthetwohybridapproacheswere

5

similar,therewerestrongvariationsintherelativecontributionsoflifecycle
inventory(LCI).Sincetheissueswerecentredoninputsattheprocesslevel,it
signalledtheneedtofurtherenhancethePCAmethodology.

ForboththeIOAandPCAapproaches,itisnecessaryforanLCAstudytoselect
an appropriate set of LCIs to reflect the local conditions and the temporal
scope of the study [17]. The selection of LCI is closely dependent on the
formulation of the life cycle system. In  the case of  a PCA, the granularity
requirementfortheLCIdatasetishigh
andcanbedifficulttoobtain.However,
thesamesetofLCIscanleadtoconsiderablydifferentresultsintheabsence
ofaproperlyformulatedLCAmethodologyinthePCAapproach.Thecauseof
suchvariationwasfoundtoberelatedtothereliabilityofthemethodological
developmentinthePCA
approach.

Usingfissionpowerasanillustration,ageneralframeworkforanLCAstudyin
thePCAapproachcanbeoutlinedasschematizedinFigure1‐2.Basedonthis
approach,severalLCAmethodologiesonfissionpower,suchas[36‐47]were
developed with corresponding life cycle carbon emission factors reported.
However,thereisalackofastandardizedmethodologyinthePCAapproach

for benchmarking the current LCA results on fission power. Without a
standardized methodology, it is also difficult  to benchmark the life cycle
carbonemissionsofalternativepowergenerationsystems.


6


Figure1‐2GeneralframeworkofanLCAonfissionpowergeneration

Basedonourassessmentonthecredibilityandreputation,wehavecarefully
selectedalistofmorethan50LCAstudiesinthePCAapproach.Thesestudies
constitute more than 90 sample points for the LCA results. Based on our
observation,the reported values of thelifecycle carbon emissionfactorsof
fission power varied by more than a factor of 100 (Figure 1‐3). Such a
magnitudeof dispersion are hardlyplausible.Itseemstosuggest that there
arereliabilityissueswiththecurrentmethodologies.Thus,itsuggeststheneed
tocarefullyinvestigatetheissuesassociatedwiththecurrentLCAstudies.In
brief,wefoundthattherewerereliabilityissuesfromboththemethodological
developmentandLCIselectionaspects.


7


Figure1‐3Lifecyclecarbonemissionsoffissionpowergenerationreported
intheliterature(logarithmplot)

In turn, these reliability issues may lead negative consequences as many
globallyrecognizedstudiesarerelyingontheLCAresultsfromtheliterature.

Pacala and Socolow [48] developed a methodology under which replacing
conventionalfossilfuelledtechnologieswithnewandcleantechnologiescould
formwedgestohelpstabilizetheatmosphericCO
2
concentration.TheIEA[23]
referenced LCA results on power generation for the development the 450
Scenario. In the discussion on future emission scenarios, the IPCC [49]
referenced LCA results from the literature for benchmarking the life cycle

8

carbon emissions from alternative power generation technologies with key
policyrecommendations.TheLCAresultswerealsousedbytheconsultantsat
Mckinsey for the development of a global Marginal Abatement Cost Curve
(MACC)[50,51].Attheregionallevel,theADBreferencedLCAresultsinthe
discussionaboutclimatechangeinSoutheastAsia[3].Atthecountrylevel,the
U.S. Energy Information Administration (EIA) referenced LCA results for the
agency’sAnnualEnergyOutlookseries [52]. Alloftheseauthoritative works
maybecomeunreliablewiththeuseofunreliableLCAresults.Assuch,itmay
leadtotheill‐informed
decisionmaking,whichcouldresultinadverseeffects
indecarbonizingtheenergysystems.

To understand the root cause of the issues with the current LCA
methodologies, we employ a scorecard me thod (explained in Appendix A),
developed by Nian and others [53]. This method allows for a systematic
evaluationonthekey
aspectsofanLCAmethodologyrelatedtoestimatingthe
life cycle carbon emissions of energy systems (explained in Chapter 2). Our
findings suggest that the cause of the issues are rooted primarily from the

system boundary definition. The definition of system boundaries originated
fromthedevelopmentofacradle‐to‐gravesystemaswellastheinput‐output
definitions.Thedefinitionsforalifecyclesystem,itsinput‐outputinteractions,
and boundary selections are fundamental to an LCA methodology on
estimatingcarbonemissions.Thus,thereliabilityissuesneedtobeaddressed
fundamentally.


9

TherewerefourotherissueswiththecurrentLCAmethodologies on power
generationintheliterature.Firstofall,noneoftheexistingLCAmethodologies
were capable of analysing “design” related issues. These “design” related
issues include projecting the life cycle carbon emissions of future and/or
advancedenergysystems,andtheinfluenceonthelifecyclecarbonemissions
from the change in de sign parameters (e.g. reactor size, enrichment
concentration, and uranium ore grade). Indicators derived from these
capabilities are very important for climate change policymaking. Secondly,
therewasnostandardizedLCAmethodologyeventhoughtheywerebasedon
asimilarframework.Inotherwords,thecurrentmethodologieswereusually
case specific. An LCA methodology for solar PV power generation system
cannotbeusedonafissionpowergenerationsystemwithoutre‐definingthe
entirelifecyclesystem.Thirdly,there wasalackofgenericrepresentationon
theenergysystems.AlifecyclesystemdefinedforsolarPVcannotbeusedto
representahybriddiesel‐backedsolarPVsystem.Theseproblemscreateda
barrier for establishing a common platform for repeatability and
benchmarking.

Inviewoftheabove discussion,the objectivesofthisdissertationare:(i)to
developagenericmethodologyforanalysingcarbonemissionsfromelectricity

generation systems usingthe LCA‐PCA approach;(ii) to establishthe cut‐off
criteria for an LCA‐PCAbyusing the genericmethodologytogether with the
concept of  Kaya Identity and decomposition; (iii) to apply the generic
methodologytodeterminethelifecyclecarbonemissionfactor(measuredin