Ekvall presentation by 4il60c93

VIEWS: 7 PAGES: 14

									                                      Chalmers University of Technology




   Attributional
and consequential
  LCI modelling
              Tomas Ekvall

      Department of Energy Technology
      Chalmers University of Technology
           Gothenburg, Sweden
    email tomas.ekvall@me.chalmers.se



InLCA/LCM 2003, Seattle, September 22-25 2003
                                             Chalmers University of Technology




 The type of LCA affects modelling

• Early proponents:
  Heintz & Baisnée (1992)
  Weidema (1993)

• Well established:
  SETAC-Europe WG
  on Inventory Enhancement

       InLCA/LCM 2003, Seattle, September 22-25 2003
                                             Chalmers University of Technology




 Types of LCA in this presentation
        (Curran et al. 2001)

• Attributional LCA, which aims at
  describing the environmental properties
  of a life cycle and its subsystems.

• Consequential LCA, which aims at
  describing the effects of changes within
  the life cycle.

       InLCA/LCM 2003, Seattle, September 22-25 2003
                                                Chalmers University of Technology




 LCI modelling – Guide in summary

• Attributional LCA:
  Include full life cycle
  Use average data
  Allocate in proportion to, e.g., economic value

• Consequential LCA:
  Include processes that are affected
  Use data that reflect expected effects of changes
  Avoid allocation through system expansion

          InLCA/LCM 2003, Seattle, September 22-25 2003
                                               Chalmers University of Technology



      Data that reflect changes
       (Azapagic & Clift 1999)
Environmental
 burdens (B)


                                   Marginal
                                   change



            Substantial
             change




                Complete
                 change


                                    Point of        Production
                                   operation        volume (Q)

         InLCA/LCM 2003, Seattle, September 22-25 2003
                                          Chalmers University of Technology



   Allocation problem at
 multifunctional processes
 (Ekvall & Weidema 2003)
               Raw material




        Multifunctional process



    Product A              Product B
 (used in the life       (used in other
cycle investigated)        life cycles)




    InLCA/LCM 2003, Seattle, September 22-25 2003
                                        Chalmers University of Technology



  System expansion
 when B depends on A
                                        Prod. of
            Raw material               product C


                                         Market for
   Multifunctional process           function provided
                                        by product B



Product A                                Use of
                                      product B/C


                                        Waste
                                      management


 InLCA/LCM 2003, Seattle, September 22-25 2003
                                                            Chalmers University of Technology



               System expansion
              when A depends on B

                        Multifunctional process                        Product B
                       (excluded from analysis)


               Waste                Product A
            management

                       Market for          Market for
 Prod. of              alternative      function provided              Prod. of
                    function provided    by product A in              Product C
Product D             by product A        the life cycle
                                          investigated




             InLCA/LCM 2003, Seattle, September 22-25 2003
                                                  Chalmers University of Technology



        Additional consequences
              (Ekvall 2003)

                       Example:
Consequences on…       Electricity efficiency   Modelling tool

…demand by other       Increased through        Partial equilibrium
consumers              price reduction          models

…economic activity     Increased through        General equilibrium
                       money savings            models

…knowledge and         Reduced through good Marketing models?
values                 example




           InLCA/LCM 2003, Seattle, September 22-25 2003
                                             Chalmers University of Technology




 Including affected processes
                           Cradle




Chain of cause
                         Change or
                     foreground system
  and effect
                                      Large uncertainty

                                    Unmanageable uncertainty

                           Grave


       InLCA/LCM 2003, Seattle, September 22-25 2003
                                               Chalmers University of Technology




                    Limitations

• Attributional LCA:
  Describes systems only
  Systems are subjective (allocation,
  geographical boundaries etc.)

• Consequential LCA:
  Describes consequences only
  Entails great uncertainty and instability

         InLCA/LCM 2003, Seattle, September 22-25 2003
                                              Chalmers University of Technology




          Suggested criteria
     for assessing methodology

• Generate relevant information
• Allow efficient communication of this
  information
• Contribute to inspire actions
• No significant adverse effects


        InLCA/LCM 2003, Seattle, September 22-25 2003
                                              Chalmers University of Technology




    Conclusions and discussion

• Consequential modelling goes far beyond
  marginal data and avoiding allocation
• Pure consequential LCAs are rare
• Terminology is confused
• Ranking methodology is not straightforward
• Choice of methodology should be deliberate


        InLCA/LCM 2003, Seattle, September 22-25 2003
                                                     Chalmers University of Technology




                        References
Azapagic A, Clift R. 1999. Allocation of environmental burdens in multiple-
      function systems. J Cleaner Prod, Vol. 7, No. 2, pp. 101-119.
Curran MA, Mann M, Norris G. 2001. Report on the International
      Workshop on Electricity Data for Life Cycle Inventories. Cincinnati,
      Ohio 45268 USA, October 23 – 25, 2001.
Ekvall T. 2003. Tools for consequential modelling. Poster presented at
      13th SETAC-Europe Annual Meeting in Hamburg, April 2003.
Ekvall T, Weidema BP. 2003. System Boundaries and Input Data in
      Consequential Life Cycle Inventory Analysis. Submitted to Int J LCA.
Heintz B, Baisnée P-F. 1992. System boundaries. In: Life cycle
      assessment. Workshop report, Leiden, The Netherlands, 2-3
      December 1991. SETAC, Brussels, Belgium, pp. 35-52.
Weidema BP. 1993. Development of a method for product life cycle
      assessment with special references to food products (summary).
      PhD thesis. Technical University of Denmark, Lyngby, Denmark.



              InLCA/LCM 2003, Seattle, September 22-25 2003

								
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