life cycle assessment (lca) in forestry – state and

Subjectreview–Pregledni rad

Croat. j. for. eng. 33(2012)2 357

Life Cycle Assessment (LCA)

in Forestry – State and Perspectives

Hans Rudolf Heinimann

Abstract – Nacrtak

Environmentally sound technologies are a key to reduce resource use and environmental impact. The paper reviews the state of knowledge of an analysis tool, life cycle assessment (LCA), by addressing three issues: 1) methodological foundations of LCA, 2) lifecycle inventory modeling, and 3) environmental performance indicators for wood supply systems. The study results in the following findings: 1) LCA is still not widely used and accepted in the forest operations engineering. 2) Only a few studies are based on state-of-the-art life cycle inventory analysis. 3) The boundaries of the studied systems are often too narrow, limiting comparability with standard LCA studies. 4) Most forest-related studies are based on direct process energy input only and are neglecting environmental burdens of upstream processes. 5) »Truncated LCAs«, neglecting embodied burdens of road infrastructure and forest machines always result in an underestimation of environmental impacts or an overestimation of environmental performance, respectively. There is a need for LCA capacity building in the forest operations community, on the basis of which forest-related LCA studies should become more comprehensive and comparable with studies of the core LCA community.

Keywords: LCA, environmental performance, wood supply, eco-efficiency, industrial ecology

1. Introduction – UvodThereisabroadconsensusthatmankindhasto

exploreandimplementpathwaysofdevelopmentthatminimize resource use while reducing emissions,wasteandimpactstostructuresandfunctionsoftheenvironmentalsystemto»nearzero«.Environmen-tallysoundtechnologies(ESTs)wereidentifiedasakeytoachievethisbroad,long-termgoal.ESTsencom-passtechnologiesthathavethepotentialtosignifi-cantly improve environmental performance, com-paredwithothertechnologies(UNEP-IETC,online).Followingthequote»whatgetsmeasuredgetsdone«,whichisattributedtoPeterDrucker,thereisaneedtoapplyand improveenvironmentalanalysis tools toproducereliable,comprehensibleenvironmentalper-formanceindicators.Thedevelopmentsincetheearly1990sledtoawholesetoftools,suchas1)lifecycleas-sessment(LCA)forproductsystems(ISO2006b),2)regionalmaterialflowanalysisforgeographicalregions(Hendriksetal.2000),or3)carbonbudgetmodelsforlarge-scalegeographicalareas(Kurzetal.2009).Those

tools,designedfordifferentcontexts,aresomewhatembeddedintheumbrellaconceptof»industrialecol-ogy«,whichlooksatindustrialsystemsthesamewayasecologistshavebeenlookingatecosystems(Erkman1997).Thekeyissueistounderstand,modelandman-agethe»industrialmetabolism«,particularlytheflowofmaterialsandenergy,tocontinuouslyincreaseenvi-ronmentalperformance(forthehistoryoftheindus-trialmetabolismthinking,see(Fischer-Kowalski1998a,b)).TheideasgobacktopioneerssuchasRobertAyres(AyresandKneese1969);CharlesHall(Halletal.1979);andHowardT.Odum(Odumetal.1977),whosethoughtsstimulatedUlfSundberg,aforestoperationsengineeringscholar,toperformsomepreliminaryen-ergyanalysisstudiesofforestoperationssystems(Sun-dbergandSvanqvist1987).Forestryhasbeenatraditionalsupplierofrenew-

ablerawmaterialsforindustrialuse(sawmilling,pulpandpaper,particleboards,etc.),forhouseholdfuelwood,particularlyintheThirdWorld,andincreas-inglyforbiofuels.Fromaproductioncontextpointof

H. R. Heinimann Life Cycle Assessment (LCA) in Forestry – State and Perspectives (357–372)

358 Croat. j. for. eng. 33(2012)2

Table 1 Positioning of LCA within set of environmental assessment and policy tools. LCA addresses the level of product systems by model-ing the life cycle of a productTablica 1. Položaj analize životnoga ciklusa unutar grupe alata okolišne politike i alata analize utjecaja na okoliš. Analiza životnoga ciklusa odnosi se na razinu sustava proizvoda, određujući životni ciklus proizvoda

Level of Action

Razina djelovanjaDefinition – Definicija

Environmental Policy Tools

Alati okolišne politike

Environmental Analysis Tools

Alati analize učinka na okoliš

Policy

Politika

A defined course of action, for guiding present and future decisions, as a result of a political weighting of interest

Definirane smjernice aktivnosti za donošenje sadašnjih i budućih odluka, a rezultat su političkoga interesa Strategic Environmental

Assessment SEA

Strateška procjena okoliša

Sustainability Impact Assess-ment SIA

Procjena učinka na potrajnost

Program

Program

A portfolio of actions, directed to a sectorial policy and usually allocating financial resources

Područje aktivnosti usmjereno na politiku sektora i dodjelu financijskih sredstava

Plan

Plan

Localization and temporal definition how and with what priority public actions should be implemented

Lokaliziranje i privremeno definiranje aktivnosti koje će se i s kojim prioritetom provesti

Project (public)

Javni projektA set of activities that is 1) limited in time, 2) directed to create a clearly defined output, 3) considering financial

constraints, and 4) fulfilling quality requirements

Skup aktivnosti koji je 1) ograničen vremenom, 2) ima jasan zadatak, 3) ograničena financijska sredstva i 4) zadovoljava

uvjete kakvoće

Environmental Impact Assessment EIA

Procjena učinka na okoliš

Sustainability Impact Assess-ment SIA

Procjena učinka na potrajnost

Project (private)

Privatni projekt

Product System

Sustav proizvoda

Collection of materially and energetically connected unit processes which perform one or more defined functions (ISO

14050)

Skup materijalnih i energetskih postupaka kojima se izvršava točno zadana zadaća (ISO 14050)

Eco-Labeling

Ekoobilježavanje

Eco-Auditing

Ekoispitivanje

Life Cycle Assessment LCA

(E-LCA, S-LCA)

Procjena životnoga ciklusa

view,LCAisasuitabletooltoassesswoodsupplysystems,becauseitwasdesignedforproductsystems(ISO2006b).Recenteffortsfosteringthedevelopmentanddeploymentofenergysystemsthatarebasedontherenewableresourcesshouldfolloweco-efficientpathways,whoseperformancehas tobebasedoncomprehensiveassessmentmethods.Thepresentpa-peraimstocriticallyreviewenvironmentalperfor-manceassessmentfromaLCA-perspective.Thepa-perlooksatwood-basedrawmaterialpathwaysonly,andalsoneglectsproductionimpactsonforestsoils.AssumingthatLCAhasnotbeenwidelyappliedandacceptedwithintheforestoperationsengineering,thepaperfirstreviewsthemethodologicalfoundationofLCA, then looksat the stateof lifecycle inventorymodeling,andfinallysynthesizesthestateofknowl-edgeonenvironmentalperformanceindicatorsforwoodproduct, forest roadandbioenergyproductsystems.

2. LCA Methodology – Metode analize životnoga ciklusa

AlthoughLCAwasstandardizedatthebeginningofthe1990s,theunderlyingmethodologyisnotwide-lyknownandacceptedwithintheforestsciencecom-munity.Therefore,itisusefultopositionLCAwithinthewholesetofenvironmentaltools,toexplaintheLCAframework,andtopresentthegenericapproachtomodellifecycleinventoriesinthefollowingpara-graphs.

2.1 Positioning of LCA within the set of environ-mental tools – Položaj analize životnoga ciklusa unutar grupe alata za procjenu utjecaja na okolišLifecycleassessment(LCA)isamethodtoquan-

tifyandimproveourunderstandingofpossibleim-pactsassociatedwithproductsaiming1)toidentify

Life Cycle Assessment (LCA) in Forestry – State and Perspectives (357–372) H. R. Heinimann

Croat. j. for. eng. 33(2012)2 359

opportunities for environmental performance im-provement,2)toinformindustrialdecision-makersonthedevelopmentofproductsandonthedesignorre-designofmanufacturingprocesses,3)toselectandquantifyenvironmentalperformanceindicators,and4)toproveenvironmentalsoundnessforeco-labelsorenvironmentalclaims(ISO2006a).However,LCAisembeddedinawholesetofenvironmentaltools(Table1),andthereisstillsomeconfusionaboutthepurposeandscopeofdifferenttoolsandaboutwhichtoolismostappropriatetotackleaspecificproblem.Thesuccessofenvironmentalpolicies,aimingto

mitigateandlimitexhaustiveresourceuse,pollutionandwastedisposal,isonlyvisibleafteractionsaffect-ingtheenvironmenthavebeenimplementedontheground.Awholesetofenvironmentaltoolswasde-velopedtofosteraprocessofchange,leadingtoenvi-ronmentallymoresoundbehavior.Table1presentsanoverview,organizedalongtwodimensions.Thefirstdimensionrepresentsthelevelofaction,frompoliciestoprograms,projectsandproductsystems,whereastheseconddimensioncharacterizesthetypeoftools:1) analysis tools and2)policy tools (UdodeHaes1996a).Analysis toolsaddress thequantificationofeco-efficiencymetrics,aimingatansweringquestionslike»howdoesapackagesystemperformcomparedtoanew,alternativesystem«.Policytools,ontheoth-er hand, are »instruments throughwhich govern-mentsseektoinfluencecitizenbehaviorandachievepolicypurposes«(SchneiderandIngram1990).Strategicenvironmentalassessmentisapolicytool

toinfluenceenvironmentalsoundnessofpolicies,pro-gramsandplans,whereasenvironmentalimpactas-sessmentaimsatimprovingtheenvironmentalsound-nessofprojects(Anonymous2002,2009).Thepurposeofimpactassessmentistoensurethatenvironmentalconsiderationsareexplicitlyincorporatedintothede-velopment decision-making process (Anonymous1999,2002,2009);itthereforeaimstoinfluencethebe-haviorofmainlypublicdecision-makers,e.g.theau-thorities responsible to approveproject proposals.Sustainabilityimpactassessmenthasitsoriginsinthefamilyofenvironmentalassessmentprocesses(SEAandEIA)andreflectsthe»triplebottomline«approachtosustainabilitybyconcurrentlyassessingenviron-mental,economicandsocialimpactsofproposedin-terventions(Popeetal.2004).Eco-labelsandeco-au-ditingaretwopolicytoolsaddressingtochangethevaluesandperceptionsofconsumersandproducers,respectively.Eco-labelingisastatement,symbolorgraphicthatindicatesanenvironmentalaspectofaproduct, a component orpackaging,whereas eco-auditingisasystematicverificationprocesstodeter-

minewhereactivitiesormanagementsystemscomplywithnormativestandards(ISO2002).Lifecycleassessmentbegantoemargeattheendof

the1960swhentheMidwestResearchInstitutecon-ductedastudyonresourcerequirements,emissionsandwaste ofdifferent beverage containers for theCoca-ColaCompany(Guinéeetal.2010).Similarstud-iesfollowedintheUSandinSwitzerland,investigat-ing environmental burdens of containersmade ofPVC, glass, sheetmetal and cardboard.However,therewasalackofacommontheoreticalframeworkandofmethodologicalconsistency(differentnameswereinuse,suchas»eco-balance«or»resourceandenergyproductionanalysis«),affectingthecompara-bilityofresultsandpreventingLCAtobecomeanac-ceptedanalyticaltool(Guinéeetal.2010).Bytheendof the 1980s, SETAC, the societyof environmentaltoxicologyandchemistry,tookresponsibilityforthetheoretical foundation and the standardization ofLCA,whichresultedinacodeofpractice(Consolietal.1993).InEurope,thetwoguidelinesdevelopedbythecenterofenvironmentalscienceintheNetherlands(Heijungs1992a,b)hadaconsiderableimpactontheLCApracticebecausetheypresentedamathematicalframeworktohandleevenhugesetsofinterrelatedprocesses.Themathematicalformalismisbasedonformerworkof(AyresandNoble1978;Koopmans1951a,b).In1994,ISO–internationalstandardsorga-nization–startedtodeveloptheISO14000standardsseries(Marsmann1997),addressingallaspectsoflife-cyclemanagement(ISO2006a),particularlyLCAprin-ciplesandframework(ISO2006b),LCArequirementsand guidelines (ISO 2006c), LCA vocabulary (ISO2002), and environmental performance evaluation(ISO1999).In2002,SETACtogetherwithUNEP–UnitedNa-

tions environmentprogram– started the so-calledlifecycleinitiative(Guinéeetal.2010),aimingtofosterlifecyclethinkingandtointegratethe»triplebottomline«(economic,social,andenvironmental)philoso-phyforgoodsandservices.Lifecycleassessment,nowcalledenvironmentallifecycleassessment–E-LCAhasmainlybeenfocusingonimpactsonthenaturalenvi-ronment,whereaslifecyclecosting–LCCaddressesthedirectcostsandbenefitsforpeople,planetandprosperity(UNEPandSETAC2009).Atooltoassesstheimpactofaproductsystemonhumanwell-beingandcorporatesocialresponsibilitywasmissing,andthelifecycleinitiativeresultedinframingandconcep-tualizinganewtool,sociallifecycleassessment–S-LCAtofill thisgap(UNEPandSETAC2009).Thisbroader,moreholisticapproachcoversallaspectsofthetriplebottomline–people,planet,andprosperity


360 Croat. j. for. eng. 33(2012)2

–andisalsocalledlifecyclesustainabilityanalysis–LCSA(Guinéeetal.2010).Thestandardizationeffortstriggeredtheintroduc-

tionofLCAintoforestryandforestindustries.OneofthefathersofLCA(UdodeHaes1996b)presentedthe»bottlenecks« thatprimaryproductionwas facing,particularly the definition of the upstream systemboundaryandco-production,whichrequirespecialallocationrules.AtthesametimeafirstconferencewasorganizedinGermany(Frühwald1995),andthemainLCAactivitiesrelatedtoforestsectoremergedinLCApioneeringcountries(Guinéeetal.2010),suchastheUS,Sweden,Switzerland,GermanyandFin-land.TheNordicpulpandpaperindustrystartedaninitiativetodevelopajointmethodologyforlifecycleinventories for forest industry in 1993 (Kärnä andEkvall1997),resultinginthedefinitionofparametersandunitsofmeasureandinapropositionofallocationrules.Atthesametime,thefirstLCAstudiesonforestoperationsandlong-distancetransportationoftimber(KarjalainenandAsikainen1996)andoneco-invento-ries of forest machines and processes (Berg 1995;Knechtle1997;ZimmerandWegener1996)appeared,yieldingoperationalperformanceindicators,particu-larlyrelatedtoenergyconsumptionandCO2emis-sion.HarmonizationeffortscontinuedwiththeEuro-peanCOST-action»lifecycleassessmentofforestandforestproducts«,whichpublishedthefindingsin2001(Karjalainenetal.2001).Lifecycleinventoriesoffor-estryandforestindustryprocessesstartedtobeinves-tigatedsystematicallyandenteredintolifecycle-inven-

tory databases, such as ecoinvent (ECOINVENT,online),orProBas(PROBAS,online).AnewwaveofLCA-typestudiesforforestoperationsappearedafter2005,e.g.(Valenteetal.2011a;Valenteetal.2011b),probablytriggeredbytheincreasinginterestinrenew-ableenergy.However,thestreamofresearchseemssomewhattobedelinkedfromtheLCAcommunity.

2.2 LCA framework – Okosnica analize životnoga ciklusaTheproceduralLCAframework,consistingof1)

goalandscopedefinition,2)inventoryanalysis,3)im-pact assessment and 4) interpretationhas been thefoundationofLCA.Table2presentsthefourphasesofLCAandthedefinitionfollowingtheISO14,000stan-dards.Therearetwocriticalissuesinscopedefinition,1)thedeterminationofsystemboundariesand2)thedefinitionofthefunctionalunit.Aswewillshowlater,systemboundariesareoftennotclear,particularlyinthe»upstream«direction.Theenvironmentalsystemhastobepartoftheanalysis,characterizedbyinputflowssuchasCO2,solarenergy,mineralresourcesandland(occupiedandtransformed).Inventoryanalysesconsistsofmappingthestructureandfunctionsoftheproductsystem,usuallyintheformofaprocessflowdiagramthatisthebasisforthefollowingmodelingofmaterials,energy,emissionandwasteflows.Inventoryanalysis is theheartofLCA, takingaconsiderableamountoftimeandbeingextremelydataintensive.Lifecycleimpactassessmentassignstheresultof

inventoryanalysistospecificimpactcategories,such

Table 2 Definition and positioning of LCA phases as defined by the ISO standardTablica 2. Određivanje i pozicioniranje faza analize životnoga ciklusa, opisanih u normama ISO

Phase – Etapa Definition – OpisRequired knowledge

Potrebno znanje

Goal and scope definition

Cilj i značaj definicije

Goal definition, e.g. environmental performance comparison of alternative systems

Definicija cilja, npr. usporedba okolišne pogodnosti alternativnih sustava

Scope definition, particularly determination of 1) system boundaries, 2) functional unit.

Značaj definicije, poglavito određivanje 1) granica sustava, 2) funkcionalnih jedinica

Systems theory

Teorija sustava

Inventory analysis – LCI

Analiza zaliha – LCI

Inventory modeling of input/output flows for specified product system(s)

Modeliranje ulaznih i izlaznih tokova za određeni proizvodni sustav

Systems theory, process engineering

Teorija sustava, tehnike postupaka

Impact assessment – LCIA

Procjena učinaka – LCIA

Impact assessment: assignment of LCI results to specific impact categories

Procjena utjecaja: zadatak utjecaja životnoga ciklusa na određene kategorije

Environmental science, Eco toxicology

Znanost o okolišu, Ekotoksikologija

Interpretation

Tumačenje

Conclusions and recommendations for process improvement.

Zaključci i prijedlozi za poboljšanje postupka

Critical thinking – Kritičko promišljanje

Decision making – Odlučivanje


Croat. j. for. eng. 33(2012)2 361

asdepletionofnonrenewableandrenewableresourc-es,greenhouseeffect,ozonedepletion,humantoxicity,acidification,etc.(Heijungs1992b).Finally,lifecycleinterpretationformulatesconclusionsandrecommen-dationsastohowtheenvironmentalperformanceofproductsystemsmaybeimproved,orwhatalterna-tiveofdifferentproductsystemsperformsbest.

2.3 Life Cycle inventory modeling of a product system – Životni ciklus zaliha proizvodnoga sustavaInventoryanalysisconsistsofthreemajorsteps:

firsttheidentificationoffunctionsandflowsoftheproductsystem;second,thequantificationofflows;andthird,thequantitativemodelingofallflowscon-vertingintoaspecificsetofoutputflows.Thesimplestapproach,tabularbalancing,isverylimitedtohandlecomplex networks of flows, resulting in so-called

»truncated«systeminventories(Joshi1999)thatdonotfulfillthecradletograverequirement.Therefore,wewillpresent the formalmathematicalapproachbelow,whichtoourknowledgeisnotwellknownintheforestsciencecommunity,andillustrateitwithapracticalexample.Productioneconomicsprovidesaformalapproach

toinvestigateprocessnetworksoreveneconomicsec-tors,whichreliesontwofundamentalconcepts:1)com-modities,and2)activities(Koopmans1951b,1951c).Anactivity,alsocalledaprocess,consistsofaspecifictech-nology, which transforms specific input-flows intooutput-flowsaccording towell-definedprocedures.Themappingofprocessnetworksasflowsonagraphhasbecomeanimportantapproachtoanalyzeenviron-mentalimpacts(Koopmans1951b,1951c).Activitiesarerepresentedasnodes,whilearcs representflowsofgoods,resources,emissions,andwastes.Theresulting

Table 3 Flow of materials, equipment components and services into the functional unit – one productive machine hour PMH of a Stihl 026C chainsaw (Knechtle 1997). Source flows are positive, whereas sink flows are negativeTablica 3. Tok materijala, sastavni dijelovi i servis radne jedinice na temelju jednoga proizvodnoga sata Stihl 026C (Knechtle 1997). Ulazni su tokovi pozitivni, dok su izlazni negativni

X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11

Steel, high alloyed, kg

Visokolegirani čelik, kg1 0 0 0 0 0 –1.166 –1.06 –0.24 –0.35 0

Steel, non-alloyed, kg

Nelegirani čelik, kg0 1 0 0 0 0 –0.088 0 0 –0.026 0

Aluminum, kg

Aluminij, kg0 0 1 0 0 0 –2.268 0 0 –0.681 0

Plastic, kg

Plastika, kg0 0 0 1 0 0 –1.127 0 0 –0.338 0

Gasoline, kg

Gorivo, kg0 0 0 0 1 0 0 0 0 0 –1.245

Chainsaw oil, kg

Ulje za motornu pilu, kg0 0 0 0 0 1 0 0 0 0 –0.296

Manufacturing, unit

Proizvodnja, komada0 0 0 0 0 0 1 0 0 0 –8E-04

Guide bar, unit

Vodilica, komada0 0 0 0 0 0 0 1 0 0 –0.005

Chain, unit

Lanac, komada0 0 0 0 0 0 0 0 1 0 –0.017

Maintenance, unit

Održavanje, komada0 0 0 0 0 0 0 0 0 1 –8E-04

Chainsaw deployment, PMH

Rad motorne pile, radni sat0 0 0 0 0 0 0 0 0 0 1


362 Croat. j. for. eng. 33(2012)2

graphisnon-cyclic,directed,andfinite.Additionally,severalsourcenodesandsinknodesmayexist,beinglocatedoutsideofthesystem’sboundaries.ThistypeofgraphhasalsobecomeknownasGOZINTO-graph,fol-lowing»thepartthatgoesinto«(Vazsonyi1954).Life-cycleassessmentbegantoemergeinthelate

1960’s,whenAyresandKneesepublishedapaperon»production,consumption,andexternalities«(AyresandKneese1969).Theystartedfromthepremisethatthecapacityoftheenvironmenttoprovideresourcesandassimilateemissionsandwastehasbecomescarce,andthatthereisastrongneedtorelieftheconceptof»freeeconomicgoods«,suchaswater,air,etc.Theirguidingideawasthatresourceextractionandenviron-mentalpollutionanditscontrolisa»materialsbalanceproblem«.Theyformulatedamathematicalapproachtomodelthematerialsbalanceproblemwithaninput-outputapproach,consideringtheproductsofphoto-synthesisandmineralresourcesasinputs,andCO2 andwasteasfinaloutputs.Flowsonagraphmayberepresentedbyasystemof

linearequations,anexampleofwhichispresentedinTable3foraStihl026Cchainsawfrom(Knechtle1997).Eachrowrepresentstheflowofacommodityfromthesourceprocess(positiveunitvalues)tosinkprocesses(negativeunitvalues).Thefirstrowrepresentstheflowofhighalloyedsteel,ofwhich–1.16kgareflowingintothemanufacturingprocess,–1.06intotheguidebar,–0.24intothechainand–0.35intomaintenance(spareparts).Rows2to11followthesamerepresentationallogic,andthewhole system is representedby11 commodities(rows)flowingbetween11processes(columns).Assum-ing that eachprocess canbe scaledbyavariablexi,whereasi=1...11thesystemof11equationscanbesolvedforX,whereasXisthevector(x1,...,x11),ifthetotalsystemoutputYisknown.ForTable3,theelementsoftheout-putvectorYare0,exceptforx11,whichisequaltooneunityofthefunctionalunit.The11×11matrixofTable3definesthechainsaw

technologyandiscalled»technologymatrix«A(Koop-mans1951b).Auniquesolutionrequires1)aquadratictechnologymatrixA,and2)aknownbalanceofinflowsandoutflowsforallcommodities.Inmatrixnotation,theequationsystem(1)ofTable3iswrittenas

A · X = Y (1)

Modelanalysisiscomplete,ifweknowthevectorX.Itcanbefoundbysolvingmatrixequation(1)forX(2).

X = A–1 · Y (2)

Equation(2)completelydescribestheflowofcom-moditiesforaspecificprocessnetwork.Assumingan

outputvectorYasbelow,equation(2)resultsinthefollowingsolutionforX.

Thescalingvector Xhasthefollowingmeaning:x5,gasolineconsumption,meansthat2.96kgofgasolineareusedforaproductivemachinehourPMH;x1,con-sumptionofhighalloysteel,meansthatabout10gofsteelareconsumedperPMH.However,themodeljustdescribesmaterialsandenergyflows,andithastobeenhancedtoanalyzetheflowsofenvironmentalbur-dens.Thereisawell-documentedapproach(Koop-mans1951b;1951c)thatassumestheflowofcommod-itiestobeproportionaltotheflowofenvironmentalburdens(linearityassumptions).Asingletypeofen-vironmentalburdenmayberepresentedbyavectorB,whichhasthesamelengthasthescalingvectorX.Table4presentseightenvironmentalburdenvectors,writtenasrows.Theburdensofmaterialsandenergycarriersweretakenfromecoinvent(ECOINVENT,on-line),whereastheburdenassociatedwithchainsawdeployment (x11) characterizes the engine-specificemissionprofileofatwo-strokeengine.Thex7tox10 processesdonothavedirectburdens,butareusedtologicallylinktheflows.ThefiguresinTable4definetheso-calledburden

matrixB,whichbymultiplicationwiththescalingvec-torXresultsintheburdenvectorbofthetotalsystem(3),resultinginthefollowingvaluesfortheStihl026Cexample.

b = B· X (3)


Croat. j. for. eng. 33(2012)2 363

TheuseofaproductivemachinehourPMHofachainsawconsumes65.8MJofprocessenergy,16.1MJofembodiedenergy,andemits4.79kgofCO2,0.29kgofCOand0.17kgofHC.Thischainsawspecificbur-denvectorBcanbereusedfortheanalysisofproduc-tionsystems,whichcontribute to comparabilityofresults.

3. State of Modeling Approaches – Pristupi modeliranja

3.1 Conceptual Models – Konceptualni modeliLifecycleinventoryanalysishastobebasedona

conceptualmodelthatdefinesthebuildingblocksofanalysisfrom»cradletograve«.TheauthorproposedaconceptualmodelthatispresentedinFig.1(Heini-mannetal.2006).Productsystemsarehierarchicallyorganized.Thehighest leveloforganization is theproductsystemlevel(Fig.1,level2,right),consistingofanetworkofhumans,machineryandfacilities.Theunderlyinglevelconsistsofmachines,madeofdiffer-entkindsofmaterialsduringthemanufacturingpro-cess.Combustionengineshavebeenthebackboneofforestmachineryandthequalityofthecombustionprocessiscrucialforallsubsequentresults.Machinesconsume resources through maintenance, whichshouldalsobeconsideredintheanalysisprocess.Thematerialsofwhichamachineismanufacturedem-

bodyenvironmentalburdensthathavetobeconsid-eredtofulfilltheir»cradletograve«requirement.En-vironmentalburdensofmaterialsaredocumentedindatabases,suchasecoinvent(ECOINVENT,online).Theecoinventdatabasecontainsinternationalin-

dustriallifecycleinventorydataonenergysupply,resourceextraction,materialsupply,chemicals,met-als, agriculture, waste management services, andtransportservices.Itisusedbyabout4’500usersinmorethan40countriesworldwideandisincludedintheleadingLCAsoftwaretoolsaswellasinvariouseco-designtoolsforbuildingandconstruction,wastemanagementorproductdesign(ECOINVENT,on-line).Similardatabasesarespine@cpm(SPINE@CPM,online),ELCD(ELCD,online),orProBas(PROBAS,online).Fig.2presentstheproductsystemforsolidwood

production,asrepresentedintheecoinventdatabase(Werneretal.2007).Thefirstfunction,biomassgrowth,consistsofthreeinputflowsfromtheenvironment,thecaptureofsolarenergy,thesequestrationofCO2,andlandoccupation.Thesecondfunction,forestman-agement,hasthreeinputflows,too,energyinput(die-selcombustion), theuseofgravelforroadmainte-nance, and the conversion of forest land intoindustrialland,whichiscausedbytheareaoccupiedbyforestroads.Thethirdfunction,harvesting,hastwoinputflows, energy input (diesel combustion) andchainsawuse(inPMH).

Table 4 Environmental burden matrix B for the Stihl 026C chainsaw. The figures for x1 to x6 were taken from the ecoinvent database (ECO-INVENT, online) (grey shaded), whereas the values for x11 characterize the combustion process in the 2-stroke engine (dark shaded)Tablica 4. B matrica okolišnoga opterećenja motorne pile Stihl 026C. Izvor je podataka x1 do x6 baza Ecoinvent, dok je vrijednost x11 rad dvo-taktnoga motora

X1 X2 X3 X4 X5 X6 X7 X8 X9 X10 X11

Embodied energy, MJ

Ugrađena energija, MJ109.7 33.3 231.4 93.32 9.216 9.21 0 0 0 0 0

Process energy, MJ

Utrošak energ. pri radu0 0 0 0 42.7 42.7 0 0 0 0 0

CO2, kg 5.282 1.614 9.964 3.229 0.505 0.503 0 0 0 0 3.926

CO, kg 0.029 0.03 0.004 0.001 9E-04 9E-04 0 0 0 0 0.285

CH4, kg 0.016 0.009 0.022 0.008 0.004 0.004 0 0 0 0 2E-04

HC, kg 0.005 0.001 0.011 0.011 0.009 0.009 0 0 0 0 0.16

NOx, kg 0.01 0.003 0.02 0.007 0.003 0.003 0 0 0 0 0.004

SOx, kg 0.343 0.005 0.058 0.019 0.003 0.003 0 0 0 0 0.001

Imported from Ecoinvent (2012) – Izvor Ecoinvent (2012)No direct burden

Bez izravnoga opterećenja

Engine combustion

Sagorijevanje


364 Croat. j. for. eng. 33(2012)2

Fig. 1 Components of the framework of life cycle inventory analysis (Heinimann et al. 2006). Recycling of materials, such as steel is assumed to be included in raw material burdensSlika 1. Dijelovi okvira analize zaliha životnoga ciklusa. Recikliranje materijala, poput čelika, pretpostavlja se da ulazi u granice sirovih materijala

Fig. 2 Conceptual mapping of energy, material and area flow for wood product systems (Werner et al. 2007)Slika 2. Konceptualno kartiranje tokova energije, materijala i područja u proizvodnji drva (Werner i dr. 2007)

Theharvestingfunctionisatypicalcaseofco-pro-duction,whichisatermformultipleproductscomingoutofonefunction(ISO2002).Co-productionrequiresrulesastohowtoallocateupstreamenvironmentalburdenstoasetofproducts,whichisoftendonepro-portionallytotheeconomicvalueoftheoutputprod-ucts.Intheecoinventdatabase,theallocationfactorsare0.86forroundwood,0.09forindustrialwood,and0.05forresidualwood.Thenatureofallocationfactorsisnormative,andthereisnorightorwrongsolutiontothisproblem.There-presentationinecoinventdoesnotfullycomplywiththe»cradletograve«require-ment thatwouldrequest to includeenvironmentalburdensthatareembodiedinforestmachines,tools,

andinforestroads.Takingintoaccounttheseshort-comings,(Heinimannetal.2006;Knechtle1997)eco-inventoriesforforestmachinesandfortheconstruc-tionandmaintenanceofforestroadsweremodeled.

4. State of environmental performance knowledge – Stanje znanja o okolišnoj

učinkovitostiTheselectionandquantificationofoperationalper-

formanceindicators(OPIs)isamainpurposeofLCA(ISO2006a).OPIsareindicatorstomeasureandcom-pare eco-efficiency (Huppes and Ishikawa 2007),


Croat. j. for. eng. 33(2012)2 365

whichisarelationshipbetweenresourceconsump-tion,emittedpollutantsordeposedwasteperaunityofthefunctionalunit.Materials-relatedindicatorsarethemassofmaterials,orthequantityofwaterusedperproductunit,whichise.g.aperformanceindicatorforpulpproductsystems.Energy-relatedOPIsspeci-fythequantityofenergyusedperproductunit,andemission-relatedOPIsthemassofspecificemissionsperproductunit(ISO1999).Below,wepresenttwotypicalOPIs,energyconsumptionandCO2emissionperfunctionalunit,asreportedinthescientificlitera-ture.

4.1 OPIs for solid wood product systems – Poka-zatelji ekološke učinkovitosti za drvne proiz-vodeTable5presentsOPIsforthe»solidwoodproduct

system«.Afirstproblemthatweencounteredduringthe screeningof the literaturewas that the systemboundarieswereeithernotclearlyspecifiedordiffer-ingacrossstudies.Theupstreamboundaryshouldinclude the environmental system (Udo de Haes

1996b)asrepresentedintheecoinventmodel(Fig.2).However, someof the studies startwith the forestmanagement function (see Fig. 2),whereas othersseemtoconsidertheharvestingfunctiononly.IntheNordiccountries,thedownstreamboundaryisusu-allyat themillgate,whereas inCentralEuropeanstudies,theboundaryisattheforestroad.Consider-ingtheearlyfindingsof(KarjalainenandAsikainen1996)thatabouttwothirdoftheenvironmentalbur-denoftheforesttomillproductsystemarecausedbyroad construction and long distance transport, itwouldmakesensetoreporttwoseparateOPIs,oneforforestmanagementandharvesting,andtheotheroneforlongdistancetransportation,includingroadinfra-structure.Asecondproblemthatweencounteredwasthefactthatmostoftheforestrystudieswereoflevel2only(seeFig.1),consideringonlydirectmaterialsandenergyconsumptionsduringsystemdeploymentandneglectingembodiedenvironmentalburdensofupstreamfunctions.Accordingto(Knechtle1997),theembodiedenergyinmachineslikeharvestersandfor-wardersequalstoabout40to50%ofthedirectprocessenergy.Thehigheremissionvaluesfromtheeco-in-

Table 5 Energy input and CO2 output for harvesting operations. The underlying harvesting systems are of harvester-forwarder type, with a motor-manual system for ecoinventTablica 5. Utrošak energije i emisija CO2 pri pridobivanju drva sustavom harvester – forvarder, osim u slučaju »Ecoivent« gdje je u pitanju ručno-strojni rad

Source – IzvorCO2

(kg m–3 ub)

Energy – Energija

(MJ m–3 ub)

Level – Razina

2 1+2

Ecoinvent 2012 12.41 4.07 kg crude oil

4,07 kg sirove naftex

ProBas 2012 17.92 501 x

SPINE@COM 2012 57 x

Berg 1997 2.4 – x

González-García et al. 2009, Spain3,4 ~22 ~90 x

González-García et al. 2009, Sweden3,4 ~14 ~40 x

Karjalainen and Asikainen 19963 6.4 – x

Knechtle 19993 7.4 110 x

Lindholm 20063 5.9 63–66 x

Schwaiger and Zimmer 2001 2.4–4.3 36 x

Valente et al. 20113 4.4 52 x

1 road maintenance included – uključeno održavanje cesta2 functional unit: 1 kg, conversion with 0.007 m3 per kg – funkcionalna jedinica 1 kg, pretvorba s 0,007 m3 po kg3 without silvicultural operations – bez uzgojnih radova4 including transport to mill – uključujući prijevoz do pilane


366 Croat. j. for. eng. 33(2012)2

ventorydatabases (Table 5) (ECOINVENT, online,PROBAS,online)mayalsobeexplainedbytheem-bodiedburden.MedianvaluesofthestudiesreportedinTable2

areabout7.5kgCO2.m-3

ubandabout60MJ.m-3ub,both

withconsiderablevariabilityanduncertainty.Thereisaneedtoimprovethequalityandcomparabilityoffuturestudiesbystandardizingthedefinitionofsys-temboundariesforthesolidwoodproductionsystemandbydefiningandinvestigatingidenticalflows.Thishastobeachievedontheconceptuallevel,asillus-tratedinFig.2.

4.2 OPIs for the construction and maintenance of forest roads – Pokazatelji ekološke učinkovitosti pri gradnji i održavanju šumskih cestaTakingtheevidencethatabout60%oftheoverall

environmental burdens of forest production arecausedbyroadnetworkinfrastructureandlong-dis-tancetransport(KarjalainenandAsikainen1996;Win-kler1997;Heinimann1999)asastartingpoint,Heini-mann andMaeda-Inaba (2004) presented an LCAstudythatfollowedtheconceptualapproachpresent-edinFig.1,performingbothlevel1andlevel2analy-sisandusingeco-inventoriesformaterialsandenergycarriersfromecoinvent(ECOINVENT,online).Table6presentsasummaryoftheresults.Onmoderateslopesupto40percent,construction

ofoneunitlength(m)offorestroadconsumesabout350MJofenergywhileemittingabout20kgofgreen-housegases.Thisamountofenergyconsumptionisequivalenttotheheatingvalueofabout10lofdieselfuel,andabout10kgofwoodmass thathas tobegrowntosequestratetheamountemittedgreenhousegas.Transportdistanceofbasecoursematerialsisthemostsensitivefactorofinfluence.Comparedtoon-site

preparationofaggregates,a50-kilometertransportincreasesenergyconsumptionbya factorofaboutfive.Slopedemonstratedtobethesecondimportantfactorthatshowsanonlinearinfluenceonenergycon-sumptionandgreenhousegasemissions.Increasingslopetoabout50percent,doublesenergyconsump-tionandgreenhousegasemissions,whileaslopeof70percentalmost triples them.Roadbedwidth is thethirdfactorofinfluence.Energyconsumptiondoublesbyincreasingitfrom4.2mto6.2m.Assumingalifecycleofaforestroadof40years,

a road density of 25 m ha–1, an average yield of10m3ha–1a—1,andallocatingtheOPIsofTable6tothefunctionalunit(m3

ub)ofthewoodproductsys-tem results inanamountof embodiedenergyof20–40MJ m–3,whichisconsiderable,comparedtotheenergyinputofharvestingoperations(Table5).Iftheannualyieldisloweredtoabout5m3ha–1a–1,theroad-inducedembodiedenergyreachesthesameorderofmagnitudeastheimpactoftheproductsystemitself.Thesefindingsillustratethatneglectingtheforestroadinfrastructureresultsinaconsiderableoverestimationofenvironmenttalperformance,particularlyforlow-yieldforestsandfordifficultterrain.

4.3 OPIs for truck transport systems – Pokaza-telji ekološke učinkovitosti pri prijevozu drva kamionimaRoadtransportationwithtruckshasbeenthemain

modeforlong-distancehauling.Allowablegrossve-hiclemass(GVM)wasstandardizedwithintheEuro-peanUnion,definingthefollowinglimitsfortrucks:2-axle18tons,3-axle26tons,4-axle32tons,and5-axle38tons.Typicalconfigurationsfortimbertransportarea3-axlemotorvehicleplus2-or3-axletrailerwithaGVMof40tons,anda3-axlemotorvehicleplus4-axletrailerwithaGVMof60tonsintheNordiccountries.

Table 6 Energy input and CO2 output for the construction and maintenance of forest roads. Functional unit: 1 m of road length. Assumptions: (1) roadbed width of 4.2 m, (2) cut slope angle of 1:1, (3) fill slope angle of 4:5, (4) base course thickness of 0.3 m, (5) surface course thick-ness of 0.08 m, and (6) base course materials transport distance of 10 kilometers, (6) increasing rock excavation on slopes steeper than 50%Tablica 6. Utrošak energije i emisija CO2 prilikom gradnje 1 m šumske ceste širine planuma od 4,2 m, nagiba usjeka 1 : 1, nagiba nasipa 4 : 5, debljine donjega stroja 0,3 m, debljine gornjega stroja 0,08 m, s prijevozom građevnoga materijala na udaljenost od 10 km i povećan iskop materijala na nagibima > 50 %

Terrain conditions – Terenski uvjetiCO2

(kg m–1)

Energy – Energija

(MJ m–1)

Level 2

Razina 2

Level 1+2

Razina 1+2

Slope >10% – Nagib >10 % 19 315 x –

Slope ~ 40% – Nagib ~ 40 % 25 405 x –

Slope ~60% – Nagib ~ 60 % 47 735 x –


Croat. j. for. eng. 33(2012)2 367

Table7givesanoverviewofenergyinputandCO2 emissionsforthesetwoconfigurations.TheGermanProBasdatabase(PROBAS,online)

providesthemostup-to-dateeco-inventoriesfortrucktransportation,consideringeuro-5emissionstandards,however,withoutfiguresfor60tonconfigurations.TheSwedishSpinedatabase(SPINE@CPM)providesfig-ures for 60 ton configurations,which are based onanalysisworkdoneinthelate1990s.Forest-specificfig-uresareonlyavailableforSweden(LindholmandBerg2005)andforFinland(KarjalainenandAsikainen1996),whereassomeresults,e.g.(Valenteetal.2011b),arenotcomparable.TheProBasdataillustratethatenviron-mentalperformancedependsonthetrafficmode(high-way,overland,inthecity),yieldinganincreasinggradi-ent from highway to in the city transport. TheSwedishdata(LindholmandBerg2005)giveapre-liminaryhintthattimberhaulagehasitsown,forest-specifictrafficmode(intheforest,overland,high-way)thatisnotwellunderstood,butprobablyresultsinburdensthatareclosetothe»inthecity«mode.Assuminga40tonconfiguration,overlandmode,andatimberloadof28m3yieldsanenergyconsump-tionofabout0.55MJ m–3

ub.Comparedtoanaverageenergyinputof60MJ m–3

ub(Table5),aroadtransportdistanceofabout100kmresultsinanenvironmentalburdenofthesameorderofmagnitudeasfromtheharvestingprocess,however,neglectingtheembodiedenergyoftheforestroadinfrastructure(seeTable6),whichaddsbetween20and40MJ m–3

ub(see4.2).

4.4 Environmental performance of bioenergy product systems – Okolišna učinkovitost sustava za proizvodnju bioenergije

IEA(2011,2012),assumedthatlow-carbontech-nologieswouldcontributetothereductionofgreen-housegasemission.Thereareseveralbioenergypath-ways(Fig.3),1)biomassinunprocessedformsuchasfirewood,forestresidues;2)biomassintermediates,suchaspelletsorbiomethanefrommanureorlandfill;3)first-generationbiofuels,madeofseed,grain,orsugar;4)second-generationbiofuels,manufacturedfromlignocellulosicbiomass,and5)third-generationbiofuels,manufacturedfromalgaeorseaweeds(IEA2011,IEA2012,NigamandSingh2011).Environmen-talperformance,particularlyCO2-andenergy-effi-ciency,isadecisivecriteriontochoosethebestcourseofactionforfuturebiomass-basedenergysupply.Comparabilityofresultsofenvironmentalperfor-

manceassessmentrequiresfirstacleardefinitionofsystemboundaries,andsecond,anagreementonthefunctionalunit,whichisusedtonormalizetheresults.Systemboundariesshouldbeofa»welltoplant«forwoodchips,»welltostove«forpellets,and»welltowheel«typeforbiofuels.Asaconsequence,functionalunitsshouldbedefinedasaunitofenergyproducedinaplantorstove(MJ),oraunitoftransportationserviceproduced(t.km,person.km).ThescreeningoftheLCAliteratureforforestfuelsupplyindicatesthatsystemboundariesarefartoonarrow,particularlyinthedown-streamdirection,andthefunctionalunit is, inmostcases,definedintraditionalforestryunits,suchasbulkvolume,bulkmass,solidtimbervolume,etc.Thekeyquestionstilliswhattechnologyrouteout

ofthepossibilitiesoutlinedinFig.3ismostcost-effec-tiveandmostenvironmentallyperforming.TheEIAtechnologyroadmaphypothesizesthatthefollowing

Table 7 Energy input and CO2 output for long-distance truck transportationTablica 7. Utrošak energije i emisija CO2 pri daljinskom transport drva kamionima

Source – IzvorGross vehicle

mass, t

Masa vozila, t

Load capacity, t

Masa tovara, t

Emission standard

Standardi emisije

CO2

(kg· t–3 · km–1)

Energy

(MJ· t–3· km–1)

ProBas 2012 (over land, no highway – izvan autoceste)

40 24 Euro 5 0.057 0.67

ProBas 2012 (highway – autocesta) 40 24 Euro 5 0.050 0.59

ProBas 2012 (in the city – gradska vožnja)

40 24 Euro 5 0.084 0.99

SPINE@COM 2012 40 26 Euro 2 0.050 0.68

SPINE@COM 2012 60 40 Euro 2 0.041 0.57

Karjalainen and Asikainen 1996 60 40 ? 0.038 –

Lindholm and Berg 2005 60 40 ? – 0.99


368 Croat. j. for. eng. 33(2012)2

bioenergysystemsarethemostpromising:1)there-placementof traditionalbiomassbyadvancedbio-masscookstovesandhouseholdbiogassystems,2)cogeneratingheat-powerplantsCHP(IEA2012).EIAhypothesizesthatadvancedbiofuels,suchascellu-losicethanol,advancedbiodiesel,bio-syntacticgasBSGfromlignocellulosicbiomassoralgaearemorecost-andeco-efficient thanfirstgenerationbiofuelsmadeofsugarandstarch(Cherubinietal.2009).Areviewpaper(Cherubinietal.2009)assessesthestateofknowledgeofdifferenttechnologypathways.Theauthorsconcludethattheavailablestudiesindicatethatelectricityorheatgenerationofbiomasshaveabetterenvironmentalperformancethanbiofuels,andthatbioenergychainsbasedonthewasteandresiduerawmaterialsoutperformchainsbasedondedicatedcrops.Theyalsomentionedthatthe»cascading«useofbiomass(e.g.firstuseasbuildingmaterial,followedbyuseforfiber,followedbyenergeticuse)havethepotentialtofurtherenhancegreenhousegassavings.ArecentLCA-study(StuckiandJungbluth2012)onsecond-generationbiofuelspresentsevidencethatsys-temsbasedonmolasse,wasteoilglycerineandpuri-fiedbiogasperformedbestwithanamountofCO2-emissionsofabout120gpkm–1,whereasoil-baseddiesel and gasoline emit about 180 g pkm–1 and200gpkm–1,respectively.However,therearestillcon-siderablechallenges(Cherubinietal.2011),particu-larlymethodologicalinconsistenciesduetotheselec-tion of different system boundaries, alternativeapproachestoestimategreenhousegasemissions,or

alternativeallocationrules.TheauthorsalsostressthatanincreasingnumberofLCA-studiesonlignocellu-losic biomass, sugarcane, or palm oil is available,whereascontributionsonpromisingfeedstocks,suchas algae, or advanced biomass processing are stillscarce.Therearestill interestingforestryshortrotation

crops,usuallybasedonwilloworpoplar(Björeson2006;Göranson2009;Gyuriczaetal.2011).Acom-parisonof alternative bioenergy cropping systems(Adleretal.2007)showedthatsystemsbasedoncorn,soybean,andalfalfaoutperformedapoplar-basedsys-temintermsofCO2emissionsbyafactorofabout1.5.Astudycomparingtwopelletproductionsystems

(sawdust,chips)(Heinimannetal.2007)resultedinthefindingthatchip-basedsupplysystemsoutper-formsawdust-basedsystemsintermsofenergyeffi-ciency,carbondioxideemission,eco-toxicity,andpar-ticle emissions (PM10) caused by highermoisturecontentofsawdust.Thepelletmanufacturingprocess,consistingofrawmaterialssupply,pelletmanufactur-ing,andpelletdistribution,causedabout60to80%ofthetotalenergyinput.Thedryingprocessisthemostimportantstepofpelletmanufacturingwithashareof60to80%,andthereforeofferingpotentialforefficien-cy improvement by using e.g. superheated steamdryertechnology.IEA technology roadmaps (IEA2011, IEA2012)

stressthatalternativebioenergypathwaysrequirerawmaterialsupplychainsthataretailoredtotheenduseandoptimizedforbotheconomicandeco-efficiency.

Fig. 3 Classification of Biofuels (Nigam and Singh 2011), modifiedSlika 3. Podjela biogoriva (modificirano prema Nigam i Singh 2011)


Croat. j. for. eng. 33(2012)2 369

However,toourknowledge,therearenocomprehen-siveLCA-studies available that investigate supplychainstailoredtospecificbioenergypathwaysasil-lustratedinFig.3.Availablestudiesonsupplychainsarelimitedinscope,astheyinvestigatetheprocessenergyuseonly,andcalculatetheemissionsduetoenginecombustionwithrulesofthumb.Therefore,thereisastrongneedtodofurtherresearchonbio-masssupplychainsfordifferentbioenergypathways(Valenteetal.2011a;Valenteetal.2011b).

5. Conclusions – ZaključciTheguidingideaofLCAistoimproveourunder-

standingoftheimpactsofalternativeproductsystemsontheenvironmentandtoquantifyenvironmentalperformanceindicators,characterizingthecontribu-tionofproductstothemainenvironmentalrisks.ThepresentcontributionreviewedthestateofLCA-relat-edresearchforproductsystemswithforestbiomassasrawmaterial.The study resulted in the followingfindings. 1)

WhereasLCA-methodologyislookingbackonaboutthirtyyearsofexperience,itisstillnotwidelyusedandacceptedwithintheforestoperationsengineeringre-searchcommunity.2)Onlyafewforest-relatedLCA-studiesarebasedonaquantitative,mathematicalstrin-gentmethodologythatusessystemsoflinearequationstocharacterizeandmodelcommodity,energy,andsub-stanceflowsfrom»cradletograve«.3)AlthoughLCAisfollowinga»welltouse«philosophy,manyforestrelatedLCA-studiesarebasedonquitenarrowsystemboundaries,andonforest-specificfunctionalunits,thuslimitingthecomparabilitywithstate-of-the-artLCA-studies.4)Mostoftheforest-relatedLCA-studiesarebasedondirectprocessenergyconsumption,measuredasfuelconsumption,andemissionfiguresthatarecal-culatedfromfuelconsumptionbygeneralassumptions.5)»TruncatedLCAs«,neglectingembeddedenviron-mentalburdensofmachinesandforestroadinfrastruc-ture,resultsinanunderestimationofenvironmentalimpactsofforestproductsystems.Whereasenvironmentalanalysistoolsseemtocon-

verge,forexamplebybringingexergyanalysis,whichisatraditionalfieldinprocessengineering,togetherwithLCA-methodology(Hau2002;HauandBakshi2004),anew,forest-specificresearchstreamhasbeenemerging,sustainabilityimpactassessmentofwoodsupplychains,forwhichaspecific,made-to-purposesoftware toolwasdeveloped,ToSIA (Lindner et al.2012).Thisnewinitiativeseemsnottobewelllinkedtosustainabilityimpactassessment(SIA)thatemergedoutofthestrategicimpactassessment(SIA)andenvi-

ronmentalimpactassessment(EIA)traditions,beingdesignedaspolicy,andnotasanalysistools.Addition-ally,itisonlyweaklylinkedtotheongoinglifecyclemanagementinitiative,whichaddressesthe»triplebot-tomline«withthreetools:environmentallifecycleas-sessment(E-LCA),sociallifecycleassessment(S-LCA),andlifecyclecosting(LCC)(UNEPandSETAC2009).Thestudyhasseveralimplicationsfortheforest

operationsresearchcommunity.First,ithastoinvestincapacitybuildingtobetterunderstandmainstreamlife-cycleassessmentmethodology.Second,thereisastrongneedtodevelopstandardsforsystemboundariesandfunctionalunitsoftypicalbioenergypathways(seeforexampleFig.3),whichisthebasistoimprovethecom-parabilityoffuturestudies.Third,lifecycleinventoriesfor road construction, roadmaintenance and roadtransportationneedtobeupdatedbecausepreviousstudiesdemonstratedthatlong-distancetransportationandforestroadinfrastructureaccountforabouttwothirdofthetotalimpactfortypicalforestproductivitysystems(HeinimannandMaeda-Inaba2004;Karjalain-enandAsikainen1996).Andforth,futurelifecyclein-ventorieshavetobelinkedtoLCIdatabases,suchasEcoinvent (ECOINVENT,online),ProBas(PROBAS,online),etc.,toaccountformaterialsandenergysys-temsofveryupstreamprocesseslikethemanufacturingofmachines.Andfifth,futurestudiesshouldprovideinformationon the standards for theassessmentofcomplianceofmachineengines,e.g.Tier1toTier4stan-dardsintheUS(DIESELNET,online-b),StageItoIVfortheEuropeanUnion(DIESELNET,online-a),be-cause there isaconsiderabledecreaseofallowableemissionwithincreasingTierandStage.

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Sažetak

Analiza životnoga ciklusa u šumarstvu – stanje i perspektivaOkolišno prihvatljive tehnologije ključne su za smanjenje potrošnje ograničenih resursa i smanjenje utjecaja na

okoliš. U radu je opisano stanje poznavanja analitičkoga alata i analize životnoga ciklusa uz razradu triju problema: 1) metodološke postavke analize životnoga ciklusa, 2) modeliranja zaliha životnoga ciklusa i 3) pokazatelja okolišne učinkovitosti pri proizvodnji drva. Rezultati istraživanja ogledaju se u sljedećim nalazima: 1) Analiza životnoga ciklusa nema široku primjenu u šumarskoj zajednici. 2) Samo je nekoliko istraživanja napravljeno temeljem najsuvremenijih analiza zaliha životnoga ciklusa. 3) Postavljene granice istraživanja često su preuske, što smanjuje mogućnost usporedbe s uobičajenim istraživanjima životnoga ciklusa. 4) Većina se istraživanja analize životnoga ciklusa u šumarstvu zasniva samo na izravnom utrošku energije te time zanemaruje opterećenje okoliša daljinjim postupcima. 5) Takva »skraćena« analiza životnoga ciklusa zanemarivanjem opterećenja koja nastaju gradnjom šumskih cesta i uporabom šumskih vozila podcjenjuje učinak na okoliš ili precjenjuje okolišnu učinkovitost. U šumarstvu je potrebno dodatno razviti analizu životnoga ciklusa kako bi buduća istraživanja bila što obuhvatnija i kako bi se što lakše mogla usporediti s osnovnim istraživanjima analize životnoga ciklusa.

Ključne riječi: analiza životnoga ciklusa, okolišna učinkovitost, proizvodnja drva, ekološka učinkovitost, industrijska ekologija

Received(Primljeno):July14,2012Accepted(Prihvaćeno):September14,2012

Author’saddress–Autorova adresa:

Prof.HansRudolfHeinimann,PhD.e-mail:hans.heinimann@env.ethz.chInstituteofTerrestrialEcosystemsDepartmentofEnvironmentalSystemsETHZürichUniversitätsstrasse228092ZurichSWITZERLAND

life cycle assessment (lca) in forestry – state and

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