Evaluation of Abiotic Resource LCIA Methods

21 Pages·2016·2.49 MB·English

resources
Article
Evaluation of Abiotic Resource LCIA Methods
RodrigoA.F.Alvarenga1,*,IttanadeOliveiraLins2,† andJoséAdolfodeAlmeidaNeto2,†
1 DepartamentodeEngenhariaAmbiental,ProgramadePós-graduaçãoemCiênciasAmbientais,
UniversidadedoEstadodeSantaCatarina(UDESC),Av.LuizdeCamões,2090ContaDinheiro,
Lages-SC88.520-000,Brazil
2 DepartamentodeCiênciasAgráriaseAmbientais,ProgramadePós-graduaçãoemDesenvolvimentoeMeio
Ambiente,UniversidadeEstadualdeSantaCruz(UESC),Rod.Ilhéus-Itabuna,
km16s/n-Salobrinho-Ilhéus-BA45.662-900,Brazil;[email protected](I.O.L.);
[email protected](J.A.A.N.)
* Correspondence:[email protected];Tel.:[phone]
† Theseauthorscontributedequallytothiswork.
AcademicEditor:MarioSchmidt
Received:9December2015;Accepted:17February2016;Published:29February2016
Abstract: In a life cycle assessment (LCA), the impacts on resources are evaluated at the area of
protection(AoP)withthesamename,throughlifecycleimpactassessment(LCIA)methods. There
aredifferentLCIAmethodsavailableinliteraturethatassessesabioticresources,andthegoalofthis
studywastoproposerecommendationsforthatimpactcategory. Weevaluated19differentLCIA
methods,throughtwocriteria(scientificrobustnessandscope),dividedintothreeassessmentlevels,
i.e.,resourceaccountingmethods(RAM),midpoint,andendpoint.Inordertosupporttheassessment,
weappliedsomeLCIAmethodstoacasestudyofethyleneproduction. ForRAM,themostsuitable
LCIAmethodwasCEENE(CumulativeExergyExtractionfromtheNaturalEnvironment)(butSED
(SolarEnergyDemand)andICEC(IndustrialCumulativeExergyConsumption)/ECEC(Ecological
CumulativeExergyConsumption)mayalsoberecommended),whilethemidpointlevelwasADP
(AbioticDepletionPotential),andtheendpointlevelwasboththeRecipeEndpointandEPS2000
(EnvironmentalPriorityStrategies). WecouldnoticethattheassessmentfortheAoPResourcesisnot
yetwellestablishedintheLCAcommunity,sincenewLCIAmethods(withdifferentapproaches)
andassessmentframeworksareshowingup,andthistrendmaycontinueinthefuture.
Keywords: abiotic; resource; life cycle assessment; LCA; life cycle impact assessment; LCIA;
method;Brazil
1. Introduction
Natural resources are essential for our society, either for provision, supporting, regulating or
culturalservices[1]. However,duetotheworldpopulationgrowth,togetherwiththeincreaseinthe
consumptionpercapitaandpoorresourcemanagement,wearebeingledtoasustainabilitycrisis.
Naturalresourcesmaybeclassifiedinseveralways,(a)renewableornon-renewable,(b)stocks,funds
orflows, (c)bioticorabiotic, amongotherclassifications[2]. Regardingthelatter, bioticresources
arethosethatcomefromlivingorganisms, whileabioticresourcesaretheresultofpastbiological
processes(e.g.,crudeoil)orchemicalprocesses(e.g.,metal).
Oneofthetoolsthatmayassistinsustainableresourcemanagement,attheindustrialscale,is
aLifeCycleAssessment(LCA).ResourcesareseenintwowaysinanLCA:(1)Inoneway,theyare
theinputsneededinindustrialprocessesfortheproductionofaproduct,andinthissensetheyare
evaluatedatthelifecycleinventory(LCI)stage;and(2)inanotherway,theyareevaluatedasanarea
ofprotection(AoP),inlifecycleimpactassessments(LCIAs),i.e.,naturalresourcesareonetypeof
environmentalimpactassessed,andtherearedifferentmethodstoevaluatetheseimpacts.
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Accordingtotraditionalclassifications[2,3],thesemethodsmaybecategorizedintothreegroups:
(1) Resource accounting methods (RAM), which make a more simplified impact analysis, focused
mainlyongroupingtheresourcesintosinglescoreindicators,asenergyormass;(2)Midpointresource
depletionmethods, thatgobeyondRAM,evaluatingimpactsrelatedtoresourcedepletiondueto
itsuse, astheuse-to-availabilityratio; and(3)Endpointresourcedepletionmethods, thatgoeven
beyondthepreviousgroup,takingintoaccounttheconsequencesofresourcedepletion,inmanycases,
throughbackuptechnology[4,5],e.g.,evaluatingtheextraeffort(energyorcost)neededtoextractless
economicallyfeasibleresources.
DuetothelackofconsensusintheLCAcommunityregardingimpactsonnaturalresources,there
areotherapproachesofhowtheLCIAmethodsevaluatethatAoP.Rorbechetal.[6]classifiedLCIA
methodsintothreegroups: (1)Methodsthataccountfortheconsumptionoflimitedresources,which
ratherevaluatetheresourcecompetitionandassumethattheyareexchangeable(asRAM);(2)Methods
thatevaluatethedepletionofresources,whichmaybesubdividedintomidpointandendpoint(and
accordingtotheauthorswouldbetterrepresenttheAoPResources);and(3)Methodsthatevaluate
theextraeffortneededinthefutureduetoactualresourceextraction(e.g.,RecipeEndpoint),which
accordingtotheauthorsdonotrepresentaspecificAoPasResources,butaremidpointimpactsthat
affectotherAoPs(humanhealthandnaturalenvironment). Dewulfetal.[7]suggestednewAoPsfor
LCAandLifeCycleSustainabilityAssessment(LCSA),proposingfiveperspectives: (P1)thesafeguard
subjectistheresourceitself;(P2)theconcernisthecapacityofthisresourcetogenerateprovisional
services;(P3)thesafeguardsubjectisthecapacityofthisresourcetogenerateotherecosystemservices;
(P4) where consequential aspects are considered, e.g., socioeconomic mechanisms are taken into
account;and(P5)theconcernishumanwell-being,givingaratherholisticperceptionbygroupingall
previousperspectives. TheauthorsalsomentionthatP4andP5gobeyondclassicalLCA,andwould
betterfitinLCSA.
EventhoughtherearedifferentwaysofgroupingLCIAmethodsinLCA,andhowtheyaffect
(different) AoPs, in this manuscript we used the rather traditional overview, proposed by ILCD
(InternationalReferenceLifeCycleDataSystem)andSwartetal.[2,3](Figure1). Inthissense,there
aresomestudiesthatalreadycriticallyevaluateddifferentLCIAmethods,forinstance,Liaoetal.[8]
evaluatedthermodynamic-basedRAM,andpointedouttheCumulativeExergyExtractionfromthe
NaturalEnvironment(CEENE)[9]andtheSolarEnergyDemand(SED)[10],astherecommended
LCIAmethodsforthatapproach. InILCD[3],wheredifferentLCIAswereevaluatedinordertomake
recommendationsfortheEuropeancontext,theAbioticDepletionPotential(ADP)[11],adaptedto
thereservebase(Reservebase,accordingtotheUSGS(UnitedStatesGeologicalSurvey),accounts
for all reserves that have the actual potential of extraction and may be economically viable in the
future. TheADPmethodoriginallyconsideredtheultimatereserve,whichwouldbetheamountofa
certainresourceintheEarth’scrust),wasrecommendedformidpointassessment,whiletherewasno
recommendationforendpointLCIAmethods. TheLifeCycleInitiative,fromUNEP-SETAC(United
Nations Environment Programme and the Society for Environmental Toxicology and Chemistry),
is an ongoing project to create a worldwide consensus on recommendations of LCIA methods
(http://www.lifecycleinitiative.org/activities/phase-i/life-cycle-impact-assessment-programme/)[12]
whichmaybeconsideredasastepforwardtowhathasbeendonebyILCD[3].
DuetothevarietyofLCIAmethodsavailableinliteratureandthecomplexityinchoosingone
foranLCAstudy,thereisademandbyLCApractitionersforsupportindecisionmakinginprivate
andpublicorganizations. Therefore,theBrazilianLifeCycleImpactAssessmentNetwork(Redede
PesquisaemAvaliaçãodoCiclodeVida,RAICV,2014),(RegimentodaRededePesquisaemAvaliação
deImpactodoCiclodeVida. SãoBernardodoCampo,11November2014,RAICV)evaluateddifferent
LCIA methods, for several impact categories, including Abiotic Resources. Nevertheless, due to
certaincharacteristicsfromtheAbioticResourcescategory(e.g.,arelativesite-genericimpact),the
resultsforthiscategorymaybeappliedtoothercountriesaswell. Aswillbeseenlater,someRAM
create characterization factors (CF) for both biotic and abiotic resources; thus, in some cases the
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in some cases the recommendation went beyond abiotic resources (for RAM). Therefore, the
recommendationwentbeyondabioticresources(forRAM).Therefore,theobjectiveofthismanuscript
objective of this manuscript was to evaluate different operational LCIA methods for (abiotic)
was to evaluate different operational LCIA methods for (abiotic) resources available in literature
resources available in literature in order to propose a recommendation .To facilitate the assessment,
in order to propose a recommendation .To facilitate the assessment, we applied some of these
we applied some of these operational LCIA methods to a case study of ethylene production in Brazil
operationalLCIAmethodstoacasestudyofethyleneproductioninBrazilthroughbio-basedand
through bio-based and fossil-based routes.
fossil-basedroutes.

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ggrroouuppiinnggss pprrooppoosseedd bbyy IILLCCDD [[33]] aanndd SSwwaarrtt eett aall.. [[22]]
2. Results and Discussion
2. ResultsandDiscussion
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HHaannccoocckk [[1144]] aanndd PPiimmeenntteell eett aall.. [[1155]],, aanndd ssttaannddaarrddiizzeedd bbyy VVDDII ((tthhee AAssssoocciiaattiioonn ooff GGeerrmmaann
EEnnggiinneeeerrss)) [[1166]].. ItI tisis aann RRAAMM tthhaatt uusseess tthhee hheeaattiinngg vvaalluuee ooff mmaatteerriiaallss aass aann aaggggrreeggaattiioonn uunniitt..
FFrriisscchhkknneecchhtt eett aal.l .[1[177] ]evevalauluataetded sesveevrearla olpoepreartiaotnioanl aLlCLICAI Amemtheotdhos dwsitwh itthhist haipsparpopacrhoa, pcho,inptoiningt oinugt
osoumtseo dmieffedrieffnecreesn caemsoamngo nthgetmhe, msu,cshu cahs athseth uesue soefo hfihgihg horo rlolwow hheaetaitningg vvaalulueess. .TThhee CCEEDD ccaann aallssoo bbee
uusseedd asasa par opxyroixnyL CinA ,LsiCncAe, itspinrecsee nitte dparedsiernectetdco rar eldaitrioenctw citohrrseelvaetiroanlo twheitrhL CsIeAveirnadl icoattohresr [1L8C,1I9A],
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tahcecoruensotsu srcoeleslyth faotrh thave ereasoceurrtcaeisn tehnaet rhgayvoe rah ceearttaining evnaelurgey, worh hicehatminagy vbaelusee,e wnhaischa mlimayit batei osneeonf atsh ae
alipmpirtoataicohn boefc tahues eapitpbreocaocmh ebsecreasutsreic itte dbetcooemneesr greetsitcrircetseodu troce esn(eforgsseitli,cn ruecsloeuarrc,esso l(afro,sgseilo, tnhuecrlmeaarl,, wsoilnadr,,
agneodthheyrdmroalp, owwinerd), aanndd bhiyodmroapsso.wIetri)s annodt baiormegaiossn. aIlti zise dnomt aet rheogdio,nbaultizaecdc omrdetihnogdt,o bAutl vaacrceonrgdain[g2 0to],
sAplavtairael-ndgiaff e[2r0en], tsiaptaiotinal-mdaifyfebreenctoiantsioidne mreadyf boer lcaonndsiudseereidf afonr aldanadp tuastieo inf aisnp ardeavpiotautsiloyn pise rpforervmioeudstloy
apveorfiodrdmoeudb tloe- acovuoindt idnoguwbilteh-cboiuonmtiansgs, wasitshu bgigoemstaesds,i nasA sluvgagreenstgeade itna Al.l[v21a]r.eSnignac eeti atlu. s[2e1s]e. nSeinrgcey, ibt ausseeds
oennetrhgeyfi, brsatsleadw oonf tthhee rfimrsotd laywna omf itchse,rtmheosdcyiennatmifiiccsr,o tbhues stncieesnstiisficn orotbsoushtingehsss iins cneotth seor ehaigreh ostihnecre LthCeIrAe
maree tohtohdesr tLhCatIAu smeeththeosdesc othnadt luawse othfet hseercmonodd ylanwam oifc tsh,ewrmhiochdyhnaasmaihcsig, hwehricshci ehnatsi fiac hriogbhuesrt nsceisesn(tsifeiec
broeblouwst)n.eFsusr t(hseeer, sbienlcoewi)t.h FausrCthFeern, tsiirneclye fiot rheanse rCgFy reenstoiurerlcye sfoarn denbeiorgmya srses(oanudrcseist ea-gnedn ebriiocm),athsse C(aEnDd
hsiated-gloewnesrcico)r,e tshfeo CrEboDt hhacdri tleorwia .scores for both criteria.
CExD
The Cumulative Exergy Demand (CExD) [22] is a RAM that uses the CED as a baseline, but
instead of using energy as the indicator, it uses exergy. Exergy of a resource or system is the
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CExD
TheCumulativeExergyDemand(CExD)[22]isaRAMthatusestheCEDasabaseline,butinstead
ofusingenergyastheindicator,itusesexergy. Exergyofaresourceorsystemisthemaximumamount
of useful work that can be obtained from it [23]. By using exergy, the CExD is able to account for
severaltypesofresources(fossil,nuclear,wind,solar,potential,biomass,water,metals,andminerals),
includingthosewithnoheatingvalue.Landuseisnotaccountedforinordertoavoiddouble-counting
withbiomass. Thismethoddoesnothavespatial-differentiatedCF,butaccordingtoAlvarenga[20],
it may be adapted to consider the regionalization for land use (as in CED). Dewulf et al. [9] and
Swartetal.[2]mentionedseveralinconsistenciesintheCExDmodeltocalculatetheexergyvalueof
metals,minerals,andbioticresources. SinceCExDusesexergy(2ndlawofthermodynamics),ithasa
higherscientificrobustnessthanCEDandahigheramountofCF.Therefore,ithadamediumscore
(higherthanCED)forthecriteriaevaluated.
CEENE
TheCEENEmethod[9]isaRAMthattriestoaggregatedifferenttypesofresourcesinasingle
unit(exergy). Itconsidersseveralelementaryflows,withahighernumberofCFthanotherRAMthat
usethesameapproach(e.g.,CExD).Moreover,itisseenasanevolutionofCExD,andbyusingexergy
insteadofenergy,ithasahigherscientificrobustnessthanCED.Liaoetal.[8]consideredCEENEas
(oneof)thebestthermodynamic-basedLCIAmethod(s). OneofthedifferencesbetweenCEENEand
CExDistheapproachusedtoaccountfortheexergyofmetalsandmineralsandforbioticresources
(biomassand/orlanduse). CEENE1.0doesnothavespatially-differentiatedCF;however,inCEENE
2.0(Thereisanevenmorerecentversion(3.0),wherethereisalsospatial-differentiationforocean
occupation(e.g.,foraquaculture),butitwasnotconsideredsinceitwaspublishedafter2014),there
isspatial-differentiationforlandusethroughtheworkofAlvarengaetal.[21]. Inthiscase,CFare
presentedindifferentscales(seeinbelow). Duetotheadvanceinthemodeltocalculateexergyfor
someresources,CEENEhasahigherscoreforscientificrobustnessthanCExDandhighernumberof
CF.Further,CEENE2.0hasregionalizedCFforlanduse. Therefore,CEENEhadthehighestscorefor
bothcriteria,incomparisontootherRAM.
SED
TheSolarEnergyDemand(SED),developedbyRuganietal.[10],isaRAMthatusestheEmergy
concept [24] as a baseline. In Emergy, the cradle of an LCA is not in the boundary between the
ecosphereandanthroposphere,asconsideredbyseveralRAM(e.g.,CEENE),butwithinthelimits
ofthegeobiosphere,i.e.,theSun,tidalenergy,andgeothermalenergy,aggregatedintoanindicator
calledsolarenergyequivalent[2]. InthisLCIAmethod,theauthorsfocusedoncreatingahighamount
of CF through the compilation of several published works that had quantified the transformities
(Transformity is the name give in Emergy scientific community to what is called as CF in LCA
community)ofdifferentnaturalresources. Regardingthepossibledouble-countingbetweenbiotic
resourcesandlanduse,SEDfollowstheapproachofCEENE,whichchoosestoaccountforlanduse(in
contrarytoCEDandCExD);therefore,wecansaythatSEDandCEENEareequivalentinthisaspect.
Aspreviouslymentioned,SEDhasahighnumberofCF,buttheyarenotregionalized. Emergyisan
approachthatisstillchallengedbythescientificcommunity,eventhoughtherearesomeeffortsto
solvesomeoftheproblemsandalignittoLCA[25,26],inwhichSEDwasaresultofthateffort. Dueto
thosereasons,SEDreceivedamedium-highscoreforbothcriteria.
MIPS
MaterialInputsPerService(MIPS)[27,28]isanindicatorofthecumulativeamountofresources
ofproduct/servicethroughitslifecycle,andsometimesiscalledaMaterialFootprint. MIPSisbased
onmaterialflowanalysis,separatingmaterialsinfiveclasses: abioticresources,bioticresources,earth
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movement,water,andair[28]. AssomeotherRAM,MIPSwasdevelopedoutsideofLCAandlaterit
wasconsideredasanLCIAmethod. SauratandRitthoff[29]proposedamethodtocalculateCFfor
ecoinventdatabasev2.2. However,theCFarenotfullymadeavailableinthatpublication,whilethe
authorsmentionthattheCFareabetaversionandthenewCFshallbeavailableinWuppertalInstitute
websiteinthefuture. EventhoughinRitthouffetal.[28]andinSauratandRitthoff[29],thepossibility
andimplementationofregionalizationismentioned,thisisinfactaregionalizationofLCI,andnot
LCIAasinCEENE2.0. Therefore,MIPSdoesnothaveregionalizedCF.SauratandRitthoff[29]and
Wiesen et al. [30] mentioned some differences between traditional MIPS assessment and LCA and
the need for adaptation of MIPS into an ecoinvent database, as the lack of elementary flows from
unusedextractedmaterialsfrommining. Duetothosereasons,MIPSreceivedamedium-lowscorefor
scientificrobustnessandamediumscoreforscope.
LREx
TheExergy-basedaccountingforlandresource(LREx)[21]isamethodfocusedonaccountingfor
landuseasanaturalresourcethroughexergy,andisproposedtobecomplementarytotheCEENE
method. Regardingtheissueofavoidingdouble-countinginbioticresourcesinRAM,LRExsuggests
toaccountforthebiomassextracted,whenthisoriginallyoccursinanaturalenvironment,andforthe
landuse,whenoriginallychangedinaman-madeenvironment,andinthiscase,basedonnatural
potentialnetprimaryproduction(NPP).Regardingthelatter,ithasspatial-differentiatedCFindifferent
scales,i.e.,site-generic(world),continent-based,country-based,region-based(forsixcountries),and
onagridscale(approximately10kmˆ10km). Inthissense,LRExhadahighscientificrobustness,
butalowscoreforscope,eventhoughitwasregionalized,sinceitwasfocusedsolelyonlanduseand
bioticresources. Infact,LRExisaspecificLCIAmethodforatypeofelementaryflow(landuse);thus,
itisproposedtobeusedascomplementarytootherRAM,andnotasasingleindicator.
ICEC/ECEC
TheIndustrialCumulativeExergyConsumption/EcologicalCumulativeExergyConsumption
(ICEC/ECEC) is an LCIA method developed by Hau e Bakshi [31] and Zhang et al. [32], based
on exergy. The method has CF that are operational for extended input-output databases, as USA
Input-OutputDatabase1997,whileotherLCIAmethods(previouslymentioned)areoperationalfor
process-basedLCI(e.g.,ecoinvent). First,theauthorstriedtooperationalizethecumulativeexergy
consumption(CExC),proposedbySzargut[33],viatheICEC.However,thismethodalsoproposes
anadditionalapproach,fillingthegapbetweenLCAandeconomicassessmentofnaturalresources
(evaluatingecosystemservices),viatheECEC[32]. Forthelatter,itusedprinciplesfromEmergy[24],
allowingforconsiderationoftheexergyconsumptionofecologicalgoodsandservicesinsolarenergy
equivalents. Therefore,ECEChasasimilarapproachtoSED,wherethecradleisattheboundaryof
thegeobiosphere. EventhoughICEC/ECECtriestoincludeecosystemservices,thisinclusionisstill
limitedforsomeimportantones,aspollinationandcarbonsequestration. Moreover,ICEC/ECECdoes
nothaveregionalizedCF.Nevertheless,ECECproposessomesolutionsforemergycriticalaspects,
suchasallocation. Forthosereasons,ICEC/ECEChadamedium-highscoreforbothcriteria.
EF
TheEcologicalFootprint(EF)isdefinedastheareaofwaterandlandneededtodirectlyand
indirectly support a certain population [34]. It divides these areas in six classes: crop land, forest,
pasture, water, infrastructure, and energy (carbon sequestration). For LCA, EF of a product may
bedefinedbytheareadirectlyandindirectlyneededduringthelifecycleofthisproduct. EFwas
operationalizedasanLCIAmethodbyHuijbregtsetal.[35],whereitwasalsoadded(throughsome
adaptations)totheareaneededfornuclearresources. EFappearedtobeagoodproxy, butitwas
notrecommendedformineral-basedproductsorthosewithhighparticulatematteremission[35].
ItmaybeinterpretedascomplementarytoCED/CExD,makingitpossibletoaccountforlanduse
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withlowuncertainty,butforthat,someadaptationsareneededtoavoiddoublecountingwithbiotic
resources. EFmayberegionalizedfordifferentscales,basedonspecificbiocapacities,butthereisno
operationalLCIAmethodwithspatially-differentiatedCF.Ontheotherhand,EF(asanLCIAmethod)
onlyconsiderselementaryflowsrelatedtofossilandnuclearresources,landuse,andCO emission.
2
Therefore,ithasalimitedscope(itdoesnotaccountformetalsandminerals),andgoesbeyondthe
AoPResourcesbyaccountingforCO emissions. Forthesereasons,thefinalscoreofthisRAMwas
2
ratherlow.
Table1.Quali-quantitativeassessmentoftheLCIAmethodsattheRAMlevelfortheAoPResources.
LCIAMethod CEENE CExD CED SED MIPS LREx ICEC/ECEC EF
Basereference [9] [22] [13,16] [10] [28] [21] [31,32] [34,35]
Criterion#1(Scope) 5 3 1 4 3 1 4 3
Criterion#2(Scientific
5 3 2 4 2 5 4 2
robustness)
Finalscore 5.0 3.0 1.5 4.0 2.5 3.0 4.0 2.5
Weevaluated Specificfor
Observation - - - - - -
v1.0andv2.0 landuse
2.1.2. MidpointLCIAMethods
ADP
AbioticDepletionPotential(ADP)wasinitiallydevelopedbyGuinée[11],waslatermodified
in van Oers et al. [36], and included in the LCIA methodology CML-IA (from the Institute of
EnvironmentalSciences(CML),namedCML-IA).TocalculateCF,ADPusesanequationthatinvolves
theextractionrateofacertainresourceandthesquaredoftheavailabilityofthisresourceindeposits.
All resources are normalized to the CF of antimony (Sb); therefore, the indicator is Sb equivalent
(Sb-eq). RegardingthedepositsusedtocalculatetheCF,originalADPusedtheultimatereserves,
whichmaybedefinedasthetotalamountofacertainsubstance(e.g.,iron)availableintheEarth’s
crust,oceansandatmosphere. Inthissense,theultimatereservealsoincludesdepositsthatarenot
economicallyortechnicallyfeasibleforextraction. Later,ADPcreatedCFforotherapproachesaswell,
i.e.,forreservebaseandeconomicreserves. ADPhasCFformetalsandminerals,andthetotalamount
ofCFisdependentontheapproachused(ultimatereserve,reservebaseoreconomicreserve). For
fossilfuels,ADPalsohasCF,butinthelatterversionsoftheultimatereserveapproach(e.g.,v4.2),the
CFarebasedonthenetheatingvalueofthefossilfuel,similartoCED(aRAM),thusnotprovidinga
midpointresourcedepletionassessment. ADPhashighscientificrobustnessinLCAcommunity,and
theapproachbasedonthereservebaseisrecommendedbyILCD[3]astheLCIAmethodtobeused
formidpointassessment. Furthermore,theamountofCFprovidedbythismethodisquitehighin
comparisontootherdepletionLCIAmethods,despitetheapproachconsidered. Inthissense,ADP
receivedhighscoresforthecriteriaconsidered.
EDIP
EDIP(EnvironmentalDesignofIndustrialProducts)1997/2003[37]isanLCIAmethodology
establishedintheLCAcommunityandtraditionallyusedfortheassessmentofproducts. ThisLCIA
methodologyconsidersseveralimpactcategories,includingthedepletionofresources,withCFfor
metals,minerals,andfossilfuels.Forthiscategory,theCFarecalculatedbyanequationthatexclusively
involvestheamountofavailableresourcesindeposits,i.e.,notconsideringtheextractionrate,asin
ADP.Therefore,thepropertyofaresourceforhavingahigh/lowextractionrateisnotaccountedfor
bytheCF.Forthisreason,EDIPreceivedalowerscorethanADPinthecriterionscientificrobustness.
ThedepositsconsideredinthisLCIAmethodarebasedontheeconomicreserves. EDIPhasahigh
amountofCFfortheresourcespreviouslymentioned,higherthanRecipeMidpoint[38],butslightly
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lowerthanADP(dependingontheapproachused). Forthatreason,EDIPhadamedium-highscore
forscope.
RecipeMidpoint
Recipe Midpoint (Recipe has two versions (midpoint and endpoint) and, regarding resource
depletion,therearedifferencesintheanalysis. Forthisreasontheywereevaluatedseparately.)[39]has
CFforfossilfuels,metalsandminerals,andtheapproachusedisdifferentforthetypesofresources.
Forfossilfuels,RecipeMidpointconsiderstheheatingvalue,i.e.,aRAMapproach,similartoCED.For
metalsandminerals,theapproachisdifferent,consideringthedepletionofthoseresourcesatmidpoint
level. Recipe Midpoint has an innovative approach, in comparison to ADP and EDIP, evaluated
throughthedepositsofminerals,andnotbythemetalsperse. Accordingtotheauthors,bydoingthis,
theLCIAmethodbetterrepresentstherealityofthemetals’geologicaldistribution,allowingthem
tocoverahighernumberofcommodities,especiallythoseextractedasby-products. Thismethod
considersthechangeintheoregrade,i.e.,thedecreaseintheconcentrationofmineralsinanoredue
toextraction. RecipeMidpointhaslessCFthanADPandEDIP,andthisisprobablyduetothehigher
complexityleveltoobtainthedataneededtocreatetheCFbytheapproachfromtheformer. Further,
RecipeMidpointhassomeinconsistenciesinthecreationofCF[40](e.g.,allocationprocedure). For
thosereasons,thismethodhadamediumscoreforbothcriteria.
ORI
ORI(OreRequirementIndicator)[40]isaspecificLCIAmethodfortheevaluationofmetaland
mineraldepletion;therefore,itdoesnothaveCFforfossilfuels,forinstance. Itusesasimilarapproach
toRecipeMidpoint,i.e.,considersthechangeinoregrade,anditsequationisthereciprocalofthe
ore grade variation, thus the change in ore mass by mass of metal extracted. However, instead of
usingasmalldatabase(locallyortemporally)togenerateCF,asperformedinRecipeMidpoint,the
authorsuseamorerobustdatabasethathasinformationfromdifferentminesformorethanadecade.
Inordertoguaranteescientificsoundness,theauthorscreatedCFsolelyforthemetalsinwhichthe
sourcefromthedatabaserepresentedmorethan50%ofworldwideproduction. Inthisway,ithasa
higherscientificrobustnessthanRecipeMidpoint. Ontheotherhand,ithadalimitednumberofCF
(9 metals). ORI has an interesting approach, indicating an option to be followed for midpoint
assessment,especiallywiththeexpansionofdataformetalsandminerals. However,sinceithassolely
9CFandisfocusedonmetalsandminerals(noCFforfossilfuels),ithasalowoperationalizationfor
LCA(laterthisLCIAmethodmaybeenhancedbytheinclusionofmoreCF),andasaconsequence,it
hadalowscoreforscopeandahighscoreforscientificrobustness.
AADP
TheAnthropogenicStockExtendedAbioticDepletionPotential(AADP)[41]maybeconsidered
acomplementarymethodfortheADP,byincludingthedepletionassessmentresourcesthathave
alreadybeenextractedfromtheirdepositsandarenowavailableintheanthroposphere(e.g.,landfill),
bringinganinnovativeconcept. However,duetothedifficultyofobtainingconsistentdata,ithasCF
forsolely10metals. SinceitisaspecificLCIAmethodformetals,itdoesnothaveCFforfossilfuels.
Forthosereasons,ithadahighscoreforscientificrobustnessandalowscoreforscope,asORI.AADP
wentthroughsomeadaptations,wheremoreCFwerecreated(35intotal),butthisnewversion[42]
wasnotconsideredinthisstudybecauseitwaspublishedafterDecember2014.
OGD
TheOreGradeDecrease(OGD)wasproposedbyVieiraetal.[43],andithasasimilarapproachto
ORI,i.e.,itevaluatedtheoregradechangeduetoextractionofmetals,basedonageologicdistribution
model. Forthisreason,ithasahighscientificrobustness,buttheauthorscreatedonlyoneCF,for
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copper,givingalowscoreforthescopecriterion. Inordertodifferentiatethisfromotherlow-scoring
LCIAmethodsatthescopecriterion(ORIandAADP),wegaveanevenlowerscoreforOGD.
Table2.Quali-quantitativeassessmentoftheLCIAmethodsatmidpointlevelfortheAoPResources.
LCIAMethod ADP EDIP RecipeMidpoint ORI AADP OGD
Basereference [11,36] [37] [39] [40] [41] [43]
Criterion#1(Scope) 5 4 3 1 1 0.5
Criterion#2(Scientific
4 3 3 5 5 5
robustness)
Finalscore 4.5 3.5 3.0 3.0 3.0 2.75
Specificfor
Specificfor Sinceithad
Observation - - - metalsat
metals onlyoneCF
anthroposphere
2.1.3. EndpointLCIAMethods
Eco-Indicator99
Eco-Indicator99isanLCIAendpointmethod,i.e.,itevaluatesthefinalimpactfromusingfossil
fuels,metalsandmineralsbytheapproachproposedinMuller-Wenk[4],whichconsiderstheincreased
(future)workloadintheextractionofmoreinaccessiblereservesresources(e.g.,marginalreserves). In
Eco-indicator99,thesurplusenergy(MJ )isusedasanaggregatedunitforresourcedepletion[44].
se
ThisresourcedepletioncharacterizationmodelisusedinotherLCIAmethodologiesaswell,suchas
inTRACI(theToolfortheReductionandAssessmentofChemicalandotherenvironmentalImpacts),
BEES(BuildingforEnvironmentalandEconomicSustainability),andImpact2002+[13]. Thebasefor
theEco-indicator99assessmentisthroughtheestimatedsurplusenergyrequiredfortheextractionof
minerals,basedonthedeclineoftheconcentrationrateintime[4,45]. Theanalysisusesgeostatistical
models to indicate the distribution structure, quantity and quality of the minerals and the future
effortneeded,tocalculatethesurplusenergyforextractionofresources. Followingthesametrend
fromotherendpointLCIAmethods,theEco-indicator99hasfewerCFthanmidpointLCIAmethods.
In addition, compared to other endpoint LCIA methods (e.g., Recipe Endpoint and EPS2000), the
numberofCFisalsolower,andwiththeabsenceofimportantmineralsintheglobalcontext,such
asgold,iron,palladium,molybdenum,leadandplatinum. Forthisreason,thescoreforscopewas
medium. Ononehand,thecharacterizationmodelispartofdifferentmethodsLCIA(e.g.,Impact
2002+),whichareconsolidatedandacceptedbythescientificcommunity,butontheotherhand,the
characterizationmodelswasbased(formetals)onalimitednumberoflowaccuracycurves. Therefore,
Eco-indicator99’sscientificrobustnesswasconsideredmedium-low,incomparisontootherendpoint
LCIAmethods.
RecipeEndpoint
RecipeEndpoint[39]assessesthedepletionoffossilfuels,metalsandmineralsthroughanother
approach(comparedtoitsmidpointversion),goingbeyondthecause-effectrelationship,i.e.,toan
endpointlevel[2,3]. Theapproach,somewhatsimilartotheEco-indicator99,evaluatestheincrease
inthecostofextractingthoseresourcesduetotheirdepletion,thususingtheapproachproposedby
Müller-Wenk[4]andStewartandWeidema[5]. BecauseitisanLCIAmethodthatgoesbeyondthe
causeandeffectofresourcedepletionimpacts,ithasgreatercomplexityofdatatocreateCF,andin
thissense,ithasfewerCFthanmidpointLCIAmethods(e.g.,ADP).Moreover,whencomparedto
otherendpointLCIAmethods,ithasmoreCFthantheEco-indicator99,forinstance. Formetalsand
minerals,CFwerecalculatedbasedonextractioncostsandontheCFofRecipeMidpoint. Therefore,
theendpointCFalsohasthesamecalculationinconsistenciesmentionedinSwartandDewulf[40]
(e.g., allocation procedure). Regarding fossil fuels, the CF for crude oil was based on data from
theInternationalEnergyAgency,assumingconstantannualproductionovertime,usingalimited
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relationshipofpriceandproductionanddetermininganarbitrarytimeperiod[46]. Additionally,due
toalackofdata,coalandnaturalgasCFwerecalculatedusingextrapolateddatafromcrudeoil. Thus,
theRecipeEndpointreceivedamedium-highscoreforthescopecriterionandamediumscoreforthe
scientificrobustnesscriterion.
EPS2000
TheEnvironmentalPriorityStrategies(EPS)isanendpointLCIAmethod,proposedforthefirst
timein1990,anditwaslatermodified;thefinalversionisnamedEPS2000[47,48]. Theprinciplefor
damageassessmentisthroughthewillingness-to-pay(WTP)approach,inwhichnaturalresourcesand
environmentalimpactsareputinmonetaryvalues. Oneoftheimpactcategoriesisnamedabioticstock
resource(ordepletionofreserves),whichevaluatesthedepletionimpacts(atendpointlevel)from
metals,mineralsandfossilresources. TheunitusedistheEnvironmentalLoadUnit(ELU),which
representsthecostsofsustainableextractionofnon-renewableresources. Consideringthelimitations
ofWTPforabioticresources,EPS2000proposesamarketscenario,inwhichtheproductioncostsofa
certainsubstanceareusedtoestimatetheCFforresourcedepletion. Thecharacterizationmodelsfrom
EPSarenotentirelytransparent,consideringthattheyarebasedonpoliticalandsocioculturalvalues.
Therefore,EPS2000hadamedium-lowscoreforscientificrobustness. ThecurrentversionofEPS2000
hasasignificantamountofCF,higherthanotherendpointLCIAmethods(e.g.,RecipeEndpoint),and
forthisreasonitreceivedahighscoreforscope. Asaconsequence,EPS2000receivedthesamefinal
scorefromRecipeEndpoint.
SuCo
The Surplus Cost (SuCo) method, proposed in Ponsioen et al. [46], aims to adapt or integrate
elementaryflowsrelatedtofossilresourcestoLCA.Therefore,thisLCIAmethodisspecificforthat
type of resource, not generating CF for metals and minerals (amongst other resource types). The
proposalfromSuCoistoassessfossilresourcescarcitybasedonthefutureincreaseinglobalcostsdue
totheuseofmarginalfossilresourcesusedinthelifecycleofproducts. Therefore,SuCofollowsthe
sametrendasEco-indicator99andRecipeEndpoint. Inpractice,SuComaybeseenasanevolution
fromRecipeEndpoint(whichmaybeseenasanevolutionfromEco-indicator99),andthatthereisa
possibilitytoincorporateSuCotoRecipeEndpointinthenextversionsofthelatter[49]. SuCohas
CFforthreetypesoffossilfuels(crudeoil,naturalgas,andcoal),fromwhichitusedspecificdatafor
thecalculationoftherespectiveresource. Therefore,ithashigherscientificrobustnessthanRecipe
Endpoint,inwhichonlydatafromcrudeoilwasused.Forthatreason,itreceivedamedium-highscore
forthatcriterion. SinceitisaspecificLCIAmethodforfossilfuels,itreceivedalowscoreforscope.
Exergoecology
Exergoecology,proposedbyValeroeValero[50,51],bringsaninnovativeapproachtotheLCA
community,wheretheauthorstrytoquantifythedepletionofmetalsandmineralsthroughtheexergy
cost,which,inasimplifiedway,wouldbetomakeacumulativeexergyconsumptionassessment,butin
theoppositedirection,i.e.,fromgrave-to-cradle. Themainideaisthatthemethodquantifiestheexergy
neededtoletthemetalbereadyforextractionthroughmining,fromitsreferencestate(whereexergy
iszero). ThismethodmaybeconsideredasevaluatingtheAoPResourcesattheendpointlevel,since
itconsiderstheconsequencesfromresourcedepletion. Exergoecologyhasaninterestingalternative
approach,butitisnotyetcompletelyoperationalforLCA,mainlyfortworeasons: (1)Throughthe
publishedarticles,wewereabletoquantifyonlysevenCF;and(2)thisoriginatesfromascientificarea
thatneedsmoreresearch,andmoreCFshouldbegenerated. Regardingthelatterreason,eventhough
exergyisalreadyestablishedinLCA,thescientificproposalfromValeroandValero[50,51]goesbeyond
traditionalexergy,i.e.,theyproposeaccountingfortheexergyfromgrave-to-cradle. Forthosereasons,
Exergoecologyreceivedalowscoreforscopeandamedium-highscoreforscientificrobustness.
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Table 3. Quali-quantitative assessment of the LCIA methods at the endpoint level for the
AoPResources.
LCIAMethod Eco-Indicator99 RecipeEndpoint EPS2000 SuCo Exergoecology
Basereference [44] [39] [47,48] [46] [50,51]
Criterion#1(Scope) 3 4 5 1 1
Criterion#2(Scientific
2 3 2 4 4
robustness)
Finalscore 2.5 3.5 3.5 2.5 2.5
2.2. CaseStudy
WeappliedanethyleneproductioncasestudytosomeoftheaforementionedLCIAmethods. We
comparedthetraditionalfossil-basedethylene(FE)tothebioethanol-basedethylene(BE),produced
from sugarcane. From the 19 different LCIA methods, 13 were selected to be applied in the case
study. SixLCIAmethodswereexcludedduetothelackofoperationalCF.TheLRExmethodwas
appliedviatheCEENEv2.0method. Further,itisinterestingtonotethatsomeLCIAmethodologies
(Impact 2002+, BEES, and TRACI) are indirectly considered in this study since they use a similar
charaRcetseourriczesa 2t0i1o6n, 5m, 13o delasEco-indicator99. ItmaybeimportanttomentionthattheLCI1A0 omf 2e1 thod
EcologicalScarcity[52]wasnotconsideredinthecasestudy,norintheprevioustheoreticalassessment,
use a similar characterization model as Eco-indicator 99. It may be important to mention that the
because it is a Swiss-based distance-to-the-target method, and is not in the scope of the Brazilian
LCIA method Ecological Scarcity [52] was not considered in the case study, nor in the previous
contetxhte.oFreotricaAl DasPs,ewssmeeunste, dbetcharuesee vite irss iao Snwsiisns-tbhaeseads dseisstsamnceen-tto-otfheb-etattregrete mvaeltuhoadti,o ann:d( 1is) nAoDt iPn vth3e. 2, an
oldersvcoeprsei oonf otfheA DBrPazthiliaatna cccoonutenxtts. fFoorrm AeDtaPls, ,wmei nuesreadls ,thanrede fvoesrssiliofnuse lisni nthSeb -aesqs,esthsmroeungt hoft hbeeuttletri mate
reserveveasl(utahtuiosnm: (1id) ApoDiPn tva3s.2s,e asns moldenert )v;e(r2s)ioAnD oPf AvD4.P2 ,thaant aecwcoeurnvtes rfsoiro mneotaflAs, DmPintehraaltsa, acncodu fonstssilf ofuremls etals
andmini nSebr-aeqls, tahsroSubg-ehq t,hteh uroltuimgahteu rletismeravtees r(ethsuers vmeisd,pwohinitl easfsoersfsomsesnilt)f;u (e2)l sAiDtaPc vc4o.u2,n at snfeowretrh veelrosiwonh oefa ting
valueA(tDhPu tshsaitm acilcaorutnotsa foRrA mMet)a;las nadnd( 3m)iAneDraPl-sI aLsC SDb-,eaqn, tAhrDouPgvhe urlstiiomnatteh aretsaesrvseesss, ewshmilee tfoarls f,omssiinl feureallss and
it accounts for the low heating value (thus similar to a RAM); and (3) ADP-ILCD, an ADP version
fossilfuelsasSb-eqthroughareservebase.
that assesses metals, minerals and fossil fuels as Sb-eq through a reserve base.
2.2.1. RAM
2.2.1. RAM
ForallfiveRAMmethods,theresultsshowedBEwithhigherenvironmentalimpactsthanFE,
For all five RAM methods, the results showed BE with higher environmental impacts than FE,
ascanbeseeninFigure2. FortheCED,CExD,CEENEv2.0,andSED,FEhadapproximatelyhalfof
as can be seen in Figure 2. For the CED, CExD, CEENE v2.0, and SED, FE had approximately half of
thetotthael tvoatalul veaolufeB oEf (BvEa (rvyairnyginbge btwetweeenen4 747%%a anndd 5544%%)).. OOnn ththe eotohtehre hrahnadn, dFE, FhEadh aapdparopxpimroaxtiemlya 3t4e%ly 34%
oftheoft othtael tvotaallu veaolufeB oEf BfoEr ftohr ethCe ECEENENEEm metehthoodd vv11..00.. TThhee mmaainin hohtosptsoptso tfsoufnodu nind eianche aocfh thoef RthAeMR AM
methomdesthaordesd airsec duisssceudssbedel boewlo.w.

Figure 2. Resource-based assessment of bio-based ethylene and fossil-based ethylene, with different
Figure2.Resource-basedassessmentofbio-basedethyleneandfossil-basedethylene,withdifferent
RAM methods, normalized to the highest value
RAMmethods,normalizedtothehighestvalue
CED and CExD had similar results, i.e., BE had greater environmental impact, mainly due to the
CenEeDrgayn cdonCteEnxt Dof hthaed ssuigmairlcaarnree (s8u6%lts–,8i7.e%.,),B aEndh aad cognrseiadteerrabelnev firraocntiomne onft tahlei mtoptaal cvta,lmuea winalsy dduuee toto the
energfyoscsoiln teennetrogfyt hecosnusguamrcpatinoen (8(61%0%–8–711%%),),a nmdaaincloyn sdidueer abtole fnraatcutiroanl ogfatsh ectoontasulmvaeldu edwuarsindgu eto
fossileetnheanrgoyl-tcoo-netshuymlepneti opnro(d1u0c%ti–o1n1 a%nd), dmieasienll ycodnusuemtoedn aintu trhael sguagsacrocannseu smtaegde.d Fuorri nthge eFtEh,a mnools-tt oo-fe tthhey lene
environmental impacts were due to the crude oil (63%–64%) and natural gas (31%–33%)
consumption in the ethylene supply chain. An interesting difference between CED and CExD was
the results for water resources, i.e., for CED, water resources were consumed mainly due to
hydropower (potential energy), while the CExD accounted not only for water from hydropower
(potential energy), but water was also used in the ethanol production process.
For the CEENE method, BE environmental impacts were mainly due to land occupation for the
sugarcane cultivation (90% in v1.0 and 85% in v2.0). Fossil fuels also had a significant contribution in
the total value (7% in v1.0 and 11% in v2.0), and from that approximately 53% was due to natural gas
consumption in the ethanol-to-ethylene production process and 22% was due to diesel consumption
during sugarcane cultivation. The main difference between v1.0 and v2.0 was land occupation, i.e., while
the former uses average European solar irradiation as a proxy, giving a higher result, the latter uses
regionalized data on natural potential NPP as a proxy (which for this case study, gave a lower value).
When using the SED, BE had more than double the total environmental impacts, and the main
hotspot was the consumption of gypsum (mineral) in the sugarcane stage, which was responsible for
more than 66% of the total environmental impact. After that, the consumption of limestone
(mineral), with 10% of total, natural gas in the ethanol-to-ethylene process (4%), and diesel at the