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Attributional and consequential LCI modelling Tomas Ekvall Department of Energy Technology Chalmers University of Techn

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 The type of LCA affects modelling Early proponents:

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Attributional and consequential LCI modelling Tomas Ekvall Department of Energy Technology Chalmers University of Techn

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  1. 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

  2. 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

  3. 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

  4. 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

  5. Environmental burdens (B) Marginal change Substantial change Complete change Point of Production operation volume (Q) Data that reflect changes(Azapagic & Clift 1999) InLCA/LCM 2003, Seattle, September 22-25 2003

  6. Allocation problem at multifunctional processes(Ekvall & Weidema 2003) InLCA/LCM 2003, Seattle, September 22-25 2003

  7. System expansion when B depends on A InLCA/LCM 2003, Seattle, September 22-25 2003

  8. Multifunctional process Product B (excluded from analysis) Waste Product A management Market for Market for Prod. of Prod. of alternative function provided function provided by produc t A in Product C Product D by product A the life cycle investigated System expansion when A depends on B InLCA/LCM 2003, Seattle, September 22-25 2003

  9. Additional consequences(Ekvall 2003) InLCA/LCM 2003, Seattle, September 22-25 2003

  10. Cradle Chain of cause Change or foreground system and effect Large uncertainty Unmanageable uncertainty Grave Including affected processes InLCA/LCM 2003, Seattle, September 22-25 2003

  11. 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

  12. 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

  13. 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

  14. 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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