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  • CARBONCOMPLIANCESettinganappropriatelimitforzerocarbonnewhomes

    Report

    CarbonemissionfactorsforfuelsMethodologyandvaluesfor2013&2016

    Date 06thOctober2010

    Authors TomLelyveldandPaulWoods,AECOM

    TheJohnsonBuilding,77HattonGarden,London,EC1N8JS

    Telephone:02076452000Website:http://www.aecom.com

    JobNo:60102149

    Reference:ZerocarbonHub

    DateCreated:22.08.10

    ThisdocumentisconfidentialandthecopyrightofAECOMLimited.Anyunauthorisedreproductionorusagebyanypersonotherthantheaddresseeisstrictlyprohibited.

  • CarbonCompliance CarbonEmissionFactorsforFuels

    1

    Contents

    Background.............................................................................................................................................. 2

    Methodology ........................................................................................................................................... 3

    Sourceofcarbonemissionfactordata ............................................................................................... 4

    CarbonEmissionFactors ......................................................................................................................... 5

    Biomass ............................................................................................................................................... 5

    Electricity ............................................................................................................................................. 7

    Gas..................................................................................................................................................... 15

    ConclusionsEmissionsfactorsforZeroCarbonHubmodelling.......................................................... 19

    Recommendationsforfurtherwork ..................................................................................................... 19

    Annex1:Mainsourcesofinformation.................................................................................................. 20

    Annex2:DefinitionofScopes ............................................................................................................... 21

  • CarbonCompliance CarbonEmissionFactorsforFuels

    2

    BackgroundAnewmethodologyforcalculatingcarbonemissionfactorsforfuelsandelectricitywasrecommendedinthereportCarbonComplianceforTomorrowsNewHomes1(CC4TNH)forusewithfutureBuildingRegulationscompliancetools.Themethodologyrecommendedforgridelectricityemissionfactorcalculationswasto:

    Useacombinedmarginalemissionfactor,basedontheUNFCCC2approach

    Includeupstreamemissions

    Includetheeffectsofothergreenhousegases(CO2equivalent)

    Becalculatedona15yearrollingaverage,fixedatasetlevelforthe3yearperiodsofBuildingRegulations

    Beupdatedannuallyforinformationtogivetheearliestpossibleindicationoffuturetrends

    TheZeroCarbonHubhasbeencommissionedbyCLGtocarryoutworkonthefutureCarbonCompliancelevelfornewzerocarbonhomesfrom2016.Inordertoprovidethemostappropriateadvice,thelikelyCO2(e)emissionfactorforgridelectricityandotherfuelsaccordingtotherecommendedmethodologyaboveisrequiredfortheBuildingRegulationsperiods20132015and20162018.

    AECOMwerecommissionedbytheZeroCarbonHubtoprovide,accordingtotherecommendedmethodologyoutlinedabove,abestestimateofCO2(e)emissionfactorsforthefollowingfuelsfortheperiods20132015and20161018:Gridelectricity;Mainsgas;Communityheatingfromboilersbiomass;Woodpelletsand;Woodchips.Emissionfactorswererequiredtobegeneratedwithinathreeweekperiod,anecessarilyshorttimescaletoenablefollowonworktobecarriedouttoconsidersolutionsavailabletomeeta2016carboncompliancetarget.

    Anumberofkeydocumentsandregulatorychangeshaveoccurredinthe6monthssincetheinitialworkinggroupinvestigatedmethodologiesforemissionfactorsandproducedinitialestimatesfortheCC4TNHreport.Theseinclude:

    UpdatedprojectionsfromtheInterdepartmentalAdvisoryGroup(IAG)(June2010)

    UpdatedDEFRA/DECCcompanyguidelinesforgreenhousegasreporting(August2010)

    TheEUagreementtotheextensiontoLargeCombustionPlantDirective(LCPD)/IndustrialEmissionsDirective(IED)extendinglifeofcoalburningpowerstationsfrom2015/16to2023

    1ZeroCarbonHub,CarbonComplianceforTomorrowsNewHomesAreviewofthemodellingtoolandassumptions,AnOverviewofFindingsandRecommendations(July2010)

    2UnitedNationsFrameworkConventiononClimateChangeCommittee

  • 3

    MethodologyThemethodologyproposedisasdetailedintheCC4TNHreportfromTopicWorkGroup2Carbonintensityoffuels3.ThismethodologywasbasedonthatsetoutbytheCleanDevelopmentMechanism(CDM)ExecutiveBoardoftheUnitedNationsFrameworkConventiononClimateChangeCommittee(UNFCCC)4whichisusedwhenassessingprojectsputforwardundertheCDM(asoperatedundertheKyotoprotocol).

    Thismethodologydefinestwomarginalemissionfactors:

    Operatingmarginalthisreferstothecohortofpowerstationsthatwouldreduceorincreasetheiroperationinresponsetochangesindemand.

    Buildmarginalthisreferstothecohortofpowerstationswhoseconstructionwouldbeaffectedbychangesindemandfromagivenproject.

    TheUNFCCCmethodologythenproposesfourapproachestocalculatinganoperationalmarginalemissionsfactor

    a) Simpleoperatingmarginal(OM)Generationweightedaveragedofallpowerplantsservingthesystemnotincludinglowcostmustrun(e.g.nuclearandwind)

    b) SimpleadjustedoperatingmarginalVariationofthesimpleOMforsystemswherelowcost/mustrunplantoperatesforaproportionoftheyearatthemargin.

    c) DispatchdataanalysisoperatingmarginalBasedonthegridpowerunitsthatareactuallydispatchedatthemargin

    d) AverageoperatingmarginalGenerationweightedaverageemissionrateofallpowerplantsservingthegridincludinglowcost/mustrunpowerplants.

    Thebuildmarginalisthencalculatedasthegenerationweightedaverageemissionfactorofthesetoffivepowerunitsthathavebeenbuiltmostrecently.

    Finallythecombinedmarginalemissionsfactoriscalculated,combinedtheoperatingandbuiltmarginals.Thedefaultassumptionfortheweightingofthesetwofactorsisa50:50average.Analternativeweightingcanbeappliedifthiscanbejustifiedbythetypeofproject.

    3ZeroCarbonHub,CarbonComplianceforTomorrowsNewHomes:Areviewofthemodellingtoolandassumptions,Topic2,Carbonintensityoffuels(August2010)www.zerocarbonhub.org/resourcefiles/TOPIC2_PURPLE_23August.pdf

    4UNFCCC/CCNUCCCDMExecutiveBoardEB50ReportAnnex14MethodologicalTool(Version02)Tooltocalculatetheemissionfactorforanelectricitysystemhttp://cdm.unfccc.int/methodologies/PAmethodologies/tools/amtool07v2.pdf

  • 4

    Sourceofcarbonemissionfactordata

    Akeyaspectoftheoriginalworkswasarecommendationthatthereshouldbeconsistencyintheuseofemissionfactorsbygovernment.Incarryingoutthispieceofworktheauthorsweremindfulofthisandthatemissionfactorscanbeusedforanumberofdifferentfunctionsincludingbutnotlimitedto:

    Informingdecisionmaking

    Individualcarbonaccounting

    NationwidecarbonaccountingtomeasureprogressagainstKyototargets

    SubsequenttothecompletionoftheCC4TNHTopic2Report5DEFRApublishedupdatedGuidelinesforGHGConversionFactorsforcompanyreporting6whichforthefirsttimeincludedbothothergreenhousegases(N2OandCH4)andupstreamemissions(emissionsfromextractionuptobutnotincludinguse).Toenableadesignertochoosethelowestcarbondesignsolutionthefullimpactofthechoiceoffuelonclimatechangefromtheemissionofgreenhousegasesshouldbeconsidered.

    The2010GuidelinestoDEFRA/DECC'sGHGConversionFactorsforCompanyReportingwereusedastheprimarysourceforemissionfactorinformationtoensureconsistencyacrossthesourcematerialusedtogenerateemissionfactors.

    5ZeroCarbonHub,CarbonComplianceforTomorrowsNewHomesAreviewofthemodellingtoolandassumptions,Topic2,Carbonintensityoffuels(August2010)www.zerocarbonhub.org/resourcefiles/TOPIC2_PURPLE_23August.pdf

    62010GuidelinestoDEFRA/DECC'sGHGConversionFactorsforCompanyReportingAugust2010www.defra.gov.uk/environment/business/reporting/conversionfactors.htm

  • 5

    CarbonEmissionFactorsEachfuelisconsideredinturnbelow

    Biomass

    Biomassisconsideredacarbonneutralfuelinthattheemissionsassociatedwithitscombustionwerepreviouslyfixedinthematerialasitgrewandwilloncemorebefixedasreplacementplantedforestsgrow.Consequentlythecarbonemissionsassociatedwiththeuseofbiomassaresolelyduetothetransportandprocessingofthefuelpriortouse.

    InSeptember2010theAECBpublishedadiscussionpaper,thatarguedthatitisfundamentallywrongtodefinebiomassburningaslowcarbon.Thereasoningproposedisthatburningbiomassleadstosimilarcarbondioxideemissionsperunitofheatasburningcoal.Whilsttreesdotakeupcarbonastheygrow,abetterusefortimbercouldbeinconstructionwhenthecarbonissequesteredforagreaterperiodoftime,andlowercarbonfuelscouldbeusedforheat.Thisdebateisnotedbutisoutsideofthescopeofthisstudy.

    DEFRAuseemissionfactorsderivedforSAP2009(consultationdraft)includingupstreamandothergreenhousegasemissions.FactorsaredetailedinTable1below.ScopesaredefinedinAppendix2.

    Table9c Scope3

    LifeCycleConversionFactorsforbiomassandbiogas

    TotalIndirectGHG

    FuelusedkgCO2(eq)perkWhNCV

    kgCO2(eq)perkWhGCV

    WoodChips 0.0158 0.015

    WoodPellets 0.0390 0.037

    Table1DEFRAbiomassemissionfactors

    EmissionfactorsusedbyDEFRAareconsistentwiththosecalculatedbytheBREandpublishedaspartoftheconsultationforSAP2009(thescopeofemissionfactorsusedinthefinalSAP2009includesupstreamemissionsbutnotothergreenhousegases).ThebreakdownofthesourcesofupstreamemissionsofCO2(eq)isdetailedinTable2below.

    Ofthesourcesofgreenhousegasesassociatedwiththeuseofbiomassasafuel,0.0056kgCO2/kWhorbetween15%and38%isduetotransportemissions.Overthetimeperiod20132032theUKplanstodecarboniseitstransportsectorthroughtheincreasedelectrificationofpassengervehiclesandLightGoodsVehiclesandtheincreaseduseofbiofuelsinHeavyGoodsVehicles.

    Anyforwardprojectionofemissionsfrombiomasswasconsideredlinkedtotherateofdecarbonisationoftransportemissions.Thereissomeuncertaintyabouthowsustainablebiofuelscurrentlyare:

    Therearecurrentlysignificantissuesrelatingtothetruecarbonefficiencyofsomebiofuelsandconcernsabouttheirimpactonotheraspectsofenvironmentalsustainabilityandfoodsupply7.

    TheGallagherReviewrecommendedarangeforuseofsustainablebiofuelsintheUKfrom5%10%oftotalfuelconsumption(48%oftotalenergyforroadtransport)in2020.

    7CommitteeonClimateChange,BuildingalowcarboneconomytheUKscontributiontotacklingclimatechange,(2008)http://www.theccc.org.uk/reports/buildingalowcarboneconomy

  • 6

    TheCommitteehastreatedrecommendedtargetsinthereviewforbiofuelpenetrationasareasonablebasisforcarbonbudgetsetting.EUandUKpolicies,whichhavesettargetsabovethatrecommendedbytheGallagherreviewarecurrentlybeingreconsidered.( BuildingalowcarboneconomytheUKscontributiontotacklingclimatechange)

    A6%reductioninthecarboncontentoftransportfuelwouldleadtoamarginalreductionincarbonemissions(0.0003kgCO2eq,0.8%1.4%)whichwhencomparedtothedifferenceincarbonemissionsfactorsofthefuelstobecomparedintheZCHstudywasconsiderednegligible.

    Chips Pellets

    kgCO2(eq)/kWhGCV kgCO2(eq)/kWhGCV

    Regeneration 0.0001 0.0002

    Harvesting 0.0011 0.0011

    Extraction 0.0001 0.0001

    Transporttochippingplant 0.0018 0.0019

    Chippingofbranchwood 0.0008 0.0008

    Transporttodryingandstorage 0.0016 0.0017

    Transporttochippingplant 0.0005 0.0005

    Chippingofwastewoodchunks 0.0002 0.0002

    Drying,storingandcooling 0.0151

    Milling 0.0007

    Pelletising 0.0047

    Transporttoheatingplant 0.0017 0.0014

    Combustionandheatgeneration 0.007 0.0089

    Total 0.0149 0.0373

    0.0056 0.0055Totaltransport

    37.6% 14.7%

    Table2BreakdownofbiomassupstreamemissionsfromSAP2009consultationtechnicaldocumentation

    Communityboilers

    TheemissionfactorforBiomasscommunityheatingusedinSAP2009arestatedtobeanaverageemissionfactorbasedonthemixofbiomassheatsourcesfromDUKES2008Table7.6usingtheemissionfactorsaboveandanadditionalemissionfactorforstraw(0.044kgCO2(eq)/kWh)

    8.Itisuncleartheexactmixoffuelsusedtogeneratethisemissionfactoranditisnotclearwhy,beingabletospecifybiomassfuelsourceforindividualboilers(Pelletsorchips),thesameoptionsarenotavailableforcommunityheatingsystems.Thesedifferences,whencomparingemissionfactorsforbiomasstogasandelectricityaremarginal.ConsequentlythisstudyconcludedthatforthepurposesoftheproposedstudytheZCHshouldusetheemissionfactorsforbiomasspublishedbyDEFRA/DECCwithnoallowancefordecarbonisationoftransport.

    Theemissionfactorsarethus0.015kgCO2(eq)/kWhforwoodchip,0.037kgCO2(eq)/kWhforwoodpelletsand0.013kgCO2(eq)/kWhforheatfromcommunityboilersfuelledbybiomass.

    8BRE,TechnicalDocumentSTP09/CO203

  • 7

    Electricity

    AmethodologyforcalculatingcarbonemissionfactorsforelectricitywasrecommendedinthereportCarbonComplianceforTomorrowsNewHomes9(CC4TNH).Specifically,thatforgridelectricitythefactorshould:

    Useacombinedmarginalemissionfactor,basedontheUNFCCCapproach

    Includeupstreamemissions

    Includetheeffectsofothergreenhousegases(carbonequivalent)

    Becalculatedona15yearrollingaverage,fixedatasetlevelforthe3yearperiodsofBuildingRegulations

    Beupdatedannuallyforinformation

    AsdetailedintheCC4TNHreportthecalculationofamarginalemissionsfactorissensitivetothedatetheoperationalmarginalisunderstoodtochangefromcoaltogasandthedatethebuildmarginalchangesfromgastolowcarbon(renewable/nuclear/fossilfuelCCS)

    AECOMhaveundertakenfurtherresearchtoidentifythemostuptodatelikelyprojectionsfortheretirementofexistingplantandthecompletionofnewbuildplant.Thereareanumberofsourcesofprojectionsoffutureenergysupplyfromthefollowingorganisations:

    Source Date

    DECCInterdepartmentalAnalystsGroup(updatedfromJanuary2010)

    June 2010

    DECCUpdatedEnergyandemissionsprojections(updatedfromJuly2009)

    June 2010

    NationalGridTransmittingBritainsEnergy2010 July 2010

    CommitteeonClimateChange December 2008

    ElectricityBuildMarginal

    TheC4TNHreportusedtheInterdepartmentalAnalystsGroups(IAG)ValuationofenergyuseandgreenhousegasemissionsforappraisalandevaluationdataupdatedinJanuary2010fortheforecastsforthedategaswasnolongerexpectedtobetheplantbuildmarginal.Thiswaspredictedtobe2030.TheIAGdefinitionofmarginalplantisunderstoodtorepresentbuildmarginalnotoperatingmarginalandisequivalenttonewgasfiredCombinedCycleGasTurbineplant.TheIAGreleasedanupdatedreportinJune2010whichmovedthisdateforwardsto2025.IntheJune2010IAGreportDECCnotethattheirenergymodelpredictsthatCCGTwillremainthemarginalplantbuiltuntilaround2025andconfirmthattheirmarginalwhichisabuildmarginalwillbeassumedtobeCCGTgasto2025.Onthisbasisthedatethebuildmarginalmovesfromgastoalowcarbonmixwastakenas2025.

    DECCexpressuncertaintyastowhatthebuiltmarginalwillbeafter2025until2040whenaloweraverageemissionsfactorof0.04kgCO2/kWhispredictedbytheirMARKALmodelling(fallingto0.02kgCO2/kWhby2050).After2025DECCassumethe(build?)marginalplantwillconsistofamixoflowcarbongenerationtechnologiesandCCGTplant,withtherelativeshareoflowcarbon

    9ZeroCarbonHub,CarbonComplianceforTomorrowsNewHomes:Areviewofthemodellingtoolandassumptions,AnOverviewofFindingsandRecommendations(July2010)

  • 8

    technologiesinthismixincreasingovertimeandtheshareofCCGTdecreasingandthenassumethatfrom2040,marginalelectricityemissionswillbethesameasaverageelectricityemissions.

    ThetwosetsofprojectionsareshowninFigure1.

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    Figure1PublishedemissionsfactorprojectionsfromDECCIntergovernmentalAdvisoryGroupcomparisonofJan2010andJune2010projections

    Thereisconsiderableuncertaintyintheprojectingoffutureenergygenerationandmajorpowerproducerplantconstruction.ForexampletheDECCUpdatedEnergyandEmissionsprojectionsseemtoindicatethatnofurtherNewGasnewbuildCCGTisexpectedafter2018(Figure2).

    Figure2ProjectedcumulativenewbuildbyplanttypeforMPPs2010to2025

    TheIADJune2010reportstates:Marginalemissionfactorswillbekeptunderreviewandupdatedasnecessaryastheyaresubjecttoconsiderableuncertaintyinthelongterm,particularlyintheelectricitysectorwhereitisunclearwhattype/mixofgenerationwillconstitutethemarginalsourceofelectricitysupply.

  • 9

    ElectricityOperationalMarginal

    FortheCC4TNHreportAECOMreviewedthedispatchdatafromElectrontounderstandwhatfuelwasdispatchedatthemarginalofdemand.Thiswasfoundtobecoal(Figure3)

    Figure3AveragefuelcontributionstogridgenerationFebruary2010,Elexontradingoperationsreport.

    Historicallytheoperationalmarginalhasfluctuatedbetweencoalandgasdependingontherelativefuelcosts.ForthepasttwowinterstheNationalGridhavepredictedthatgaswouldbetheoperatingmarginalandthenhavefoundthatthehistoricdispatchdataindicatesthatcoalwasthemarginaloperatingplant.Lowergaspricesleadtoitsuseasbaseloadgeneratingplant.

    TheNationalGridWinterConsultationReport2010/11predictsthatgaswillbetheoperatingmarginalwithcoaloperatingasbaseloadgeneratorforthenextwinter:

    Winter2010/11OutlookGasFuelpricefuturesshowanincreaseintheoilandcoalpricewithgasalsoincreasingalbeitretainingaseasonalprofile.Thecurrentmidwinterpriceofgassuggestscoalmaybethewinterbaseloadplantwithgasfiredgenerationasthemarginalplant.However,aswehaveobservedchangesinthefuelpricesforthepasttwowinterswhichhasleadtogasbeingusedforbaseloadgeneration,ourcurrentforecastassumesthiswillhappenagainandgas,ratherthancoal,isforecasttobebaseload.

    ReviewoftheMay2010Elexontradingoperationsreportindicatesthatcoaliscurrentlyoperatingasthesummermarginalplant(Figure4)

  • 10

    Figure 4 Average fuel contributions to grid generationMay 2010, Elexon trading operationsreport.

    Projectingintothefuture,theavailabilityofcoalfiredpowergenerationissettodecreaseduetotheincreasingimpactoftheLargeCombustionPlantDirective(LCPD)andtheIndustrialEmissionsDirective(IED).ThehighercarbonemissionsassociatedwiththegenerationofelectricityfromcoalhasalsoreducedthepricecompetitivenessofcoalduetotheEuropeanUnionEmissionsTradingScheme(EUETS).NewbuildcoalfittedwithdemonstrationCarbonCaptureandStorage(CCS)isexpectedtobeoperatedasbaseloadproducerwhilstplantaffectedbytheemissionsdirectiveswillrunforreducedhoursdrivingthisplanttocontinuetooperateatthemarginal.

    Inpredictingabestestimateofelectricityemissionsfactorsfor20132016and20162019wehavetakenasimpledispatchdataapproachtodeterminingthemarginalplant.BasedonthedispatchreportingfromtheElexontradingoperationsreportasimpledispatchdatamethodologywasusedassumingthattheoperationalmarginalwillremaincoaluntilthelastunabatedcoalplantisretired.

    InFebruaryApril2010whentheCC4TNHworkwasundertakentheLCPDwaspredictedtoforcetheclosureoftheoldestcoalburningpowerstationsby2015.TheLCPDisoneofthesevenexistingEUdirectives,includingtheIPPCthatwasrecastundertheIndustrialEmissionsDirective(IED).PriortotheendorsementbytheEuropeanParliamentoftheIED(7thJuly2010)therequirementsofLCPDwerethesubjectofhardnegotiatingbythosememberstates(includingtheUK)withsignificantcoalgeneratingcapacity.Asaresult,thetextoftheendorsementstatesthatmemberstatescanputinplace"transitionalnationalplans"togiveLCPsuntilJuly2020tomeettherequirements.Olderplantscancontinuetooperatebeyondthisdateiftheiroperatinghoursdonotexceed17,500hoursafter2016andiftheyclosebytheendof2023.

    Thelatest(June2010)projectionsforthedecommissioningofunabatedcoalstationswereprovidedbyDECC(Figure5)indicatingthatDECChavelargelyupdatedtheirprojectionstotakeaccountofatransitionalplanforplantdecommissioningthatrunsupto2023.TheDECCprojectionsincludeoneplantclosingin2024.

  • 11

    Theavailabilityofthisplantfrom2016to2024isofconsiderableuncertainty.Howplantisoperatedwilllikelydependonfactorsincludingtherateofcommissioningofnewgasandnuclearplant;therelativepriceofcoalandgas,thecostofcarbonwithintheEUETS,theneedforintermittentavailabilitytosupportperiodsoflowrenewablegenerationetc.Iftheoldercoalplantsweretorunfor17,500hourswith80%availabilitythentheywouldberequiredtoclose2.5yearsafter2016mid2019.Itisconsideredunlikelythatcoalwouldremainthesummerandwintermarginalasiscurrentlythecaserightupuntil2023or2024.Therewillbeaperiodoftailoffwherecoalatthemarginofoperationwouldcontributelessthan10%oftheannualUKpowergeneration.Forthisstudytheassumptionwastakenthatcoalwillnolongerbetheoperatingmarginalfrom2022.Furtherworkisrecommendedtounderstandtherangeoflikelyoperatingscenariosfortheprojectedmixafter2018.

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    Figure5DECCplannedPlantClosure20112025

    ThecombinedmarginalemissionfactorisrepresentedinFigure6belowtogetherwiththeIAGmarginalandaverageprojections.Thekeypointsthatdefinethecombinedmarginalare:

    ThedateatwhichcoalfiredpowerstationsceasetooperateandtheoperatingmarginaldropstoalevelreflectingoldergasfiredCCGTplant.

    Thedateatwhichnewbuildpowerstationsaresolelyverylowcarboni.e.nuclear,renewableandfossilfuelplantswithcarboncaptureandstorage(CCS).

    ThedateatwhichgasfiredCCGTplantceasestobetheoperatingmarginalplantandcoalfiredCCSisassumedtobecomemarginal(assumedtobepost2035andnotplottedbelow).

  • 12

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    UNFCCCmarginal 15yrrollingave

    Figure6Build,Operating,AverageUNFCCCmarginalemission factorprojectionsand15yearrollingaverage.

    Inprojectingemissionsfactorsfor20132016and20162019,andtakinga15yearrollingaverage,emissionsassumptionsarerequiredupto2034.GasCCGTisassumedtocontinuetobetheoperatingmarginalpost2034.Thedateatwhichnewbuildcomprisessolelylowcarbongenerationisassumedtobe2025,whengaswouldnolongerbethebuildmarginal.Theseassumptionsarediscussedinmoredetailbelow.

    TheemissionsfactorshowninFigure6aboveanddetailedinTable3belowformarginalnewbuildgasplantwastakentobeforNewbuildCCGTusingLNGsourcednaturalgas.Theemissionfactorforoperatingmarginalgasplant(post2022)wastakenasexistingbuildCCGTusingnaturalgas.ConversionefficienciesandtransmissionlossesweresourcedfromtheDefra/DECCemissionfactorsforcompanyreporting10.

    Scope111 Scope3 AllScopes

    CO2 CH4 N2O

    TotalD

    irect

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    FuelTypekgCO2/kWhGCV

    kgCO2(eq)/kWhGCV

    kgCO2(eq)/kWhGCV

    kgCO2(eq)/kWhGCV

    kgCO2(eq)/kWhGCV

    kgCO2(eq)/kWhGCV

    % %

    kgCO2(eq)/kWhGCV

    Coal(electricitygeneration)

    0.31907 0.00006 0.00277 0.32190 0.05265 0.375 36.4% 8.00% 1.11

    NaturalGasexistingbuild

    0.18485 0.00027 0.00011 0.18523 0.01799 0.203 46.7% 8.00% 0.47

    LNGnewbuildCCGT

    0.18485 0.00027 0.00011 0.18523 0.06488 0.250 50.8% 8.00% 0.53

    10Additionalsource:conversationwithMrDavidWilsonatDECC(NewbuildGasCCGTandtransmissionlosses)

    11SeeAppendix2fordefinitionofScopes

  • 13

    Table3Emissionfactorsusedindeterminationofelectricityemissionfactor.

    Takenasa15yearaveragethismethodologygeneratesthefollowingemissionfactorsformarginalelectricityfortheperiods20132016and20162019(Figure7).

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    20132016GridElec=0.642kgCO2eq/kWh

    20162019GridElec=0.527kgCO2eq/kWh

    NB:15yraveragefactorsnotcalculatedpost2019

    Figure7Electricityemissionfactors20132016and20162019

    Emissionfactorsareheavilyinfluencedbythedateunabatedcoalisnolongerconsideredtheoperationalmarginal.TheimpactofmovingthisdatebytwoyearsisshowninTable4below.

    DateOperatingmarginalchangesformCoaltoGas

    Emissionsfactor

    kgCO2eq/kWh

    20132016 20162019

    2020 0.599 0.484

    2022 0.642 0.527

    2024 0.685 0.570

    Table 4 Sensitivity of electricity emission factor to period of time Coal operates asmarginalplant.

    TheUNFCCCmethodologyidentifiesthattheoperationalmarginalshouldcomprisethelast10%ofplanttobedispatched.IfcoalisthelastfueltobedispatchedduetolimitedoperatinghoursandhighercarboncostfromtheDECCpredictionofelectricitygeneration(Figure8)itseemspossiblethatcoalcouldreasonablybeconsideredthemarginaluntilcirca2022,dependingontheproportionofcoalconsumedinnewdemonstrationCCSpowerplant(whichisnot100%abated).Furtherworkisrequiredtoconsiderlikelyplantoperationoverthisperiod.

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    Figure8ElectricitygenerationbysourceDECCupdatedemissionprojectionJune2010

    TheUNFCCCcalculationapproachisapplicableonlywhenlowcostmustrunplantcompriseslessthan50%ofthegenerationmix.By2025oneDECCpredictionoftheproportionofgenerationmixindicatesthatlowcostmustrunwillcompriseapproximately45%ofthegenerationmix(Figure8).Itisrecommendedthattheprojectionforfuturemarginalplantpost2025andtheassumptionthatchangesinmarginalplantoccurasclearstepchangesbeexploredfurther.

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    Gas

    GasconsumptionintheUKispredictedtodeclineduetoimprovementsinenergyefficiencyinbuildingsbeforeslowlystartingtoriseaftercirca2025(Figure9).

    HomeproductionofnaturalgasfromtheUKContinentalshelf(UKCS)isindecline.ImportsfromNorwayareprojectedtostabilisein2014andplateaubeforemarginallydeclining.InTransportingBritainsEnergy2010theNationalGridpredictthatintermsofmeetingthetotalUKimportrequirement,theNorwegiancontributionfallsfromapproximately67%in2009/10toonly24%in2020/21.ProjectionsbytheNationalGrid(Figure10)andDECCindicatethatLiquefiedNaturalGas(LNG)importedfromoverseasanddegasifiedforinjectionintothenationalgridisexpectedtomakeupthegapinsupplyanddemand.

    NationalGridforecastsindicateasteadyincreaseinLNGimportsbeforeanincreasedrequirementpost2015assuppliesfromboththeUKCSandNorwayareforecasttodecline.TheNationalGridpredictLNGwillmakeupover40%ofUKsupplyby2020/21.

    Figure9:DECCProjectionsofPrimaryEnergyDemand

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    Figure10:NationalGridBaseCaseAnnualSupply10yearoutlook

    Takingamarginalapproachtogasconsumptionwehavemadetheassumptionthatabuildmarginaltheadditionalgasrequiredtomeetarisingdemand,orthegasnotrequiredifdemandisfallingwillbeLNG.

    TheDEFRAemissionfactorsforgasaredetailedinTable5below.Thebreakdownofemissionfactorshighlightsthecarbonemissionsassociatedwiththeliquefaction,transportandregasificationofLNGpriortoinjectionintotheNationalGrid.Indirectgreenhousegasemissionsresultina35%increaseintheCO2eqemissionsfactorforLNG.Thiscomparestoa10%increasefornaturalgaswheretheprimarysourceofupstreamemissionsisunderstoodtobeduetomethaneleakageinextractionandtransport.

    Scope1 Scope3 AllScopes

    CO2 CH4 N2OTotalDirectGHG

    Total

    IndirectGHG

    GrandTotalGHG

    FuelTypekgCO2perkWh

    kgCO2eqperkWh

    kgCO2eqperkWh

    kgCO2eqperkWh

    kgCO2eqperkWh

    kgCO2eqperkWh

    LNG 0.185 0.00027 0.00011 0.185 0.065 0.250

    NaturalGas 0.185 0.00027 0.00011 0.185 0.018 0.203

    Table5DEFRA/DECCemissionfactorsforgasusedintheUK

    Theoperationalmarginalistakenasthetop10%oftheoperatingsupply(UNFCCCmethodology).DiscussionswithMrMikeEarpatDECCidentifiedthatUKgasmarginalsupplyissourcedfromastorageresourcecomprisingshort,mediumandlongrangestorage.FromFigure11belowthemajorityofmarginalsupplycanbeseentobesourcedfrommediumandlongrangestoragepredominantlyexistingexhaustedgasfields(e.g.RoughintheNorthSea)andsaltcaverns.

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    Figure11:NationalGridGasSupplybuildup1stOctober2009to31stMarch2010

    UKGasstoragelocationsarefilledoversummermonthswhenthereislowerdemandforheat.Gasiscompressedto200barandstoredinlocationssuchasRoughforreleaseintothesystemattimesofwinterpeakdemand.

    Thelatestsourcedsummerdatawasfrom2008.ForthatyearsummergasdemandwassourcedfromUKCS,NorwayandimportsfromthecontinentwithasmallproportionofgasimportedasLNG.ItwasthereforeassumedthatgasstoredinlongandmediumrangestoragewouldprincipallyhaveanemissionsfactorassociatedwithnaturalgasnotLNG.Theassumptionwasmadethatoperationalmarginalisnaturalgasthatisstoredoversummermonthsanddischargedovertheheatingseason.

    ThisinitialanalysiswouldbenefitfromamoreindepthapproachtoconsiderthefutureUKgasmixinsummermonthswhenstorageisrecharged.FromtheprofileinFigure11theautumnandspringmonthsmightcompriseaproportionofLNGand/orInterconnectorimport(BBL).AssuchtheremaybeacasefortheoperationalmarginaltobeacombinationofLNGandnaturalgas.FurthermoreitislikelythatovertimethesummerimportofLNGwillincreaseandthattheoperationalmarginalwouldtendfurthertowardsLNG.

    Bynatureoftheshorttimeframeofthisworkthegasemissionsfactorhastakenasimplisticinterpretationofthecomplexoperatingarrangementsemployedbythenationalgridandallthesupplierstoensureconstantsupplyofgasismaintained.ThisdoesnottakeaccountoftheuseofshorttermbulletLNGstorageofnaturalgastomanagepeakloads.Theassumptionwastakenthatasthisisthemostexpensiveformofshortrangestorageitwouldbeunlikelytoberequiredtoprovidesignificantcapacityinthesummerwhenthereisgenerallyexcesscapacityonthenetwork.

    Energyassociatedwithgascompressionforstorage

    Naturalgasiscompressedtoaround200barforstorageattheRoughgasfield.Theenergycostofcompressionofmethanefrom85bar(assumedpressureofgrid)to200barstoragepressurewascalculatedtobelessthan0.7%ofthecalorificcontentofthefuelandsowasassumednegligibleforthepurposeofthisstudy.

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    Figure12GasDemandBuildupSummer200812

    Reviewingthenationalgrid2010summerprojections(Figure13)LNGistheonlysourceofgassupplypredictedtoincreaseinthesummermonthssupportingtheassumptionthatLNGisthebuildmarginal.

    Figure132010SummerforecastofGassupplybysource

    TheMarginalemissionsfactorforgaswascalculatedasa50:50splitbetweenLNGandnaturalgastobe0.227kgCO2(eq)/kWh

    Tomaintainaconsistentapproachtothechoiceoffuelsa15yearrollingaverageofemissionsfromgasshouldbecalculatedtoenablethedesignertomakeaninformeddecisiononthelifetimecarbonemissionsoftheirheatingfuelchoice.OvertimeitispredictedthatLNGmightcompriseanincreasingproportionofsummergasconsumption,increasingtheemissionsfactorofstoredgasandleadingtoahighercombinedmarginaltendingtowardsamaximumemissionsfactorof0.25kgCO2/kWh.ItwasnotpossibletosourceprojectionsofsummerUKgasconsumptionsinordertobeabletosensiblyprojectthesummermixandtheimpactonourassumptionsoftheoperationalmarginal.Withoutfurtherdetailedworkanassumptionofa50:50splitbetweenLNGandnaturalgaswasconsideredsufficientlyrobustfortheZCHwork.

    12UKNationalGridGasMonthlySummerUpdateOctober2008

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    ConclusionsEmissionsfactorsforZeroCarbonHubmodellingBasedontheworkdescribedabovethefollowinginterimemissionsfactorsarerecommendedforuseintheZerocarbonhubcarboncompliancework.

    EmissionfactorkgCO2eq/kWhGCV

    20132016 20162019

    Gridelectricity 0.642 0.527

    MainsGas 0.227 0.227

    Biomasschip 0.015 0.015

    Biomasspellet 0.037 0.037

    Biomasscommunityheating 0.019 0.019

    Table620132016and20162019emissionfactors

    Emissionfactorsfor20132016and20162019arehigherthanthosecurrentlyinuseinPartL2010.ThisisinpartduetotheuseofCO2equivalentemissionfactorsbutmostsignificantlyduetotakingamarginalapproachtotheimpactofchangesindemandonelectricitysupplyratherthanagridaverageapproach.

    Recommendationsforfurtherwork TheUNFCCCcalculationapproachisapplicableonlywhenlowcostmustrunplantcompriseslessthan50%ofthegenerationmix.By2025oneDECCpredictionoftheproportionofgenerationmixindicates(Figure8)thatlowcostmustrunwillcompriseapproximately45%ofthegenerationmix.Itisrecommendedthattheprojectionforfuturemarginalplantpost2025andtheassumptionthatchangesinmarginalplantoccurasclearstepchangesbeexploredfurther.

    Furtherworkisrequiredtoconsiderlikelyplantoperationovertheperiod20162023.

    Forthisstudytheassumptionwastakenthatcoalwillnolongerbetheoperatingmarginalfrom2022.Furtherworkisrecommendedtounderstandtherangeoflikelyoperatingscenariosfortheprojectedmixafter2018.

    ItisrecommendedthatthecalculationoftheemissionsfactorforelectricitybeconsideredusingthegasmarginalemissionsfactorinthecalculationofthebuiltandoperatinggasCCGTemissionsfactorsinsteadofseparateUKCSnaturalgasandLNGemissionsfactors.

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    Annex1:MainsourcesofinformationThemainsourcesofinformationusedbyAECOMtoinformthisworkareasfollows:

    Emissionfactors

    2010GuidelinestoDEFRA/DECC'sGHGConversionFactorsforCompanyReporting

    August2010

    WelltoTankReportVersion3.0,APPENDIX2DescriptionanddetailedenergyandGHGbalanceofindividualpathways

    November2008

    BRE,TechnicalDocumentSTP09/CO202MethodologyfortheGenerationofUKEmissionFactorsforuseintheNCM(Mar2009)

    March2009

    BRE,TechnicalDocumentSTP09/CO203RevisedEmissionFactorsforuseintheNCM:Datasourcesandassumptions

    March2009

    DigestofUKEnergyStatistics2010(DUKES) July2010

    TheGreenhouseGasProtocol

    acorporateaccountingandreportingstandardSeptember2001

    Projectedplantbuildout

    DECC,Valuationofenergyuseandgreenhousegases(GHG)emissionsforappraisalandevaluation:backgrounddocumentation(June2010)

    June2010

    DECC,UpdatedEnergyandEmissionsProjections(June2010) June2010

    DECC,EnergyMarketsOutlook(Dec2009) December2009

    NationalGrid,TransportingBritainsEnergy2010:DevelopmentofEnergyScenarios(July2010)

    July2010

    NationalGrid,ThepotentialforRenewableGasintheUK(Jan2009)

    January2009

    Methodology

    UNFCCCAnnex14MethodologicalTool(V02)Tooltocalculatetheemissionfactorforanelectricitysystem.

    October2009

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    Annex2:DefinitionofScopes

    Excerptfrom2010GuidelinestoDEFRA/DECC'sGHGConversionFactorsforCompanyReporting(page5)

    Whatisthedifferencebetweendirectandindirectemissions?

    ThedefinitionusedinusedintheGHGProtocolfordirectandindirectemissionsisslightlydifferentthanfortheseAnnexes(whichareconsistentalsowiththeGovernment'sActonCO2CalculatorandCarbonOffsettingAccreditationScheme). In theseAnnexesdirectandindirectemissionsaredefinedasfollows:

    DirectGHG emissions are those emissions emitted at the point of use of a fuel/energycarrier(orinthecaseofelectricity,atthepointofgeneration).

    Indirect GHG emissions are those emissions emitted prior to the use of a fuel/energycarrier (or in the case of electricity, prior to the point of generation), i.e. as a result ofextracting and transforming the primary energy source (e.g. crude oil) into the energycarrier (e.g. petrol). Emissions from the production of vehicles or infrastructure are notconsidered.

    TheGHGProtocoldefinesdirectandindirectemissionsslightlydifferentlyasfollows:

    DirectGHG emissions are emissions from sources that are owned or controlled by thereportingentity.

    Indirect GHG emissions are emissions that are a consequence of the activities of thereportingentity,butoccuratsourcesownedorcontrolledbyanotherentity.

    WhataretheGHGProtocolScopes1,2and3

    TheGHGProtocolfurthercategorizesdirectandindirectemissionsintothreebroadscopes:

    Scope1:DirectGHGemissionsemittedatthepointofcombustionoffuels.

    Scope2:IndirectGHGemissionsfromconsumptionofpurchasedelectricity,heatorsteam.(=DirectGHGemissionsfromtheproductionofelectricity,heatorsteam.)

    Scope3:Indirectemissions,suchastheextractionandproductionofpurchasedmaterialsandfuels,transportrelatedactivities invehiclesnotownedorcontrolledbythereportingentity,electricity related activities (e.g.T&D losses)not covered in Scope2,outsourcedactivities,wastedisposal,etc.

    OutsideofScopes:Emissionsdata fordirectCO2emissions frombiologically sequesteredcarbon(e.g.CO2fromburningbiomass/biofuels)arereportedseparatelyfromthescopes.