A Framework for Computer Aided Modeling, Design, a

1AFrameworkforComputerAidedModeling,Design,andOptimizationofIntegratedIndustrialSystemsEricD.WilliamsInstituteofAdvancedStudies,TheUnitedNationsUniversityMatthiasTroyer1InstituteofSolidStatePhysics,UniversityofTokyoContactInformation:EricWilliamsInstituteofAdvancedStudies,TheUnitedNationsUniversity,53-67Jingumae,5-chome,Shibuya-ku,Tokyo150-8304,[e-mail]modelinganddesignofindustrialsystemspresentsgreatpotentialforfacilitatingtheconstructionofindustrialsystemswhichmaximizeutilizationofmaterials,minimizeemissionsofharmfulwastes,andpreserveeconomicfeasibility.Aframeworkformodelingindustrialsystemsthatistoformthebasisofadesignsystemisdescribed.Themodeltakesanindustrialsystemtobeacollectionofprocesseseachcharacterizedbytheirinputsandoutputsofmaterials,energy,finances,andlabor.Akeyconceptisthatofthehierarchicalinput/outputtableformaterialsandenergy,whichisformulatedtofacilitatetheintegrationofindustrialprocesses.Theoutputofthemodelactstoevaluatetheeconomicandenvironmentalperformanceofthesystem,thusprovidingameanstocomparedifferentconfigurations.Themodelhasascale-invariancepropertythatreflectsthefractalnatureofsystemswithnestedflows.Suggestionsaregivenforacomputerdesignsystemforindustrialclusters,whereinalgorithmsareusedtosearchprocessdatabasestogeneratedesignswhichlinkindustriestogethertomaximizeutilizationandprofitability.IntroductionThecurrentsocietal-industrialsystemisunsustainableinthatitconsumesandemitsvastquantitiesofrawmaterialsandenergywithlittleconsiderationofthelong-termeffectsonhumanityandeco-systems.Thescaleofhumanactivitieshasreachedthesameorderofmagnitudeasthescaleoftheearth’secosystemsandresources,thuscreatingthepotentialtosignificantlyaltertheearthtothedetrimentoffuturegenerations.Thusifsocietyistoprosperinthelongterm,itisnecessarytobetterunderstandandcontroltheeffectsofhumankind’sactionsonitselfandtheenvironment.Theneedsandwantsofhumansocietiesaremetthroughtheactionsofindustry.Thus,akeypointinprogressingtowardsasustainablesocietyisfindingmeanstoreducetheenvironmentalloadof1AffiliatedwithETH,ZurichfromSeptember19982industrialactivities.Currentindustryfunctionsunderthemarketsystem,whichimpliesthattheprimarydesignconsiderationofindustrialsystemsisthemaximizationofprofit.Thus,howtoprogresstowardssustainableindustryinthecontextofthemarketsystemisacrucialquestion.Oneapproachtoaddressingthisissueistheintegrationofindustrialactivities.Ashumanknowledgeprogresses,wegainagreaterunderstandingandabilitytomanagecomplexsystems.Inthecontextofindustryandsustainability,IndustrialEcology(FroschandGallopoulos1989),IndustrialMetabolism(Ayres1994),andZeroEmissions(Pauli1996)haverecentlycomeforwardasapproachesaddressinghowasystemsviewpointcanaddresstheissueofsustainableindustry.Thecommonthemeintheseapproachesistolookbeyondtheindividualprocessesofextraction,manufacture,consumption,andre-usetoconsiderhowtheylinktogethertoformasystem.Atypicalindustrialsystemtodayis“open”,meaningthatmaterialsandenergyaretakeninanddisposedoffreely,themainconstraintbeingtheminimizationofcostforproducingagivenproduct.Suchopensystemsgenerallyonlyutilizeasmallfractionoftheinputmaterialsandenergy,toprogresstowardssustainableindustrythereisclearlyaneedto“close”thesystemasmuchaspossible.Animportantcomponentofclosingthecycleofmaterialsandenergyistheintegration,orclustering,ofindustrialactivities.Integrationinthiscontextisthelinkingofindustrialprocessessuchthatinterconnectedwholeutilizesmaterialsandenergyeffectivelyandemitsminimalwaste.Thekeypointishowoutputsofagivenprocesscanbeusedasinputforotherprocesses,insteadofbeingdumpedoremittedandthusbecomingwaste.Anespeciallyattractiveaspectofsuchlinkingisthatasinmanycasesfindingauseforwastesgenerateseconomicvalue,ithaspotentialtoincreaseprofitabilityaswellasreduceenvironmentalimpacts.ZeroEmissionsemphasizesthisvalue-addeduseofoutputsasinputsasakeytocreating“industrialclusters”,whicharegroupsofindustrieslinkedtogetherinsymbioticrelationshipstominimizewasteandmaximizeprofitability.Thereissometendencyforindustrialsystemstoself-organizetowardsintegration,asevidencedbymanyexamplesofindustriessellingunused“wastes”foruseinothercontexts.Generally,thesepointsofconnectionwereestablishedthroughbilateralrecognitionoftheeconomicadvantagesbetweenthetwopartiesinvolvedintherelevantprocesses.Anexampleofwherethisbilateralself-organizationhasresultedinahighlevelofintegrationoccursintheindustrialdistrictatKalundborg,Denmark(Ehrenfeld1997).However,lookingatindustryoverall,theaveragedegreeofintegrationwouldappeartoberatherlowincomparisonwithitspotential.Inadditiontobilateralself-organizationofintegratedindustries,whichproceedswithoutanyoverallplan,itisimportanttoconsiderthepotentialforachievingintegrationthroughcarefulorganizationofthesystem.Thisplanningcouldbedonethroughamultilateralprocessinvolvingdifferentparties,and/orthroughoneortwopartieshavingcontroloveraseriesofprocesses.Themodernoilrefineryisanexampleofsophisticatedprocessintegrationwithinagivenindustrialsector.Controlleddesignprese