Evaluation of Life Cycle Assessment Recycling Allocation Methods

12 Pages Posted: 12 Oct 2013

See all articles by Jeremiah X. Johnson

Jeremiah X. Johnson

University of Michigan at Ann Arbor - School of Natural Resources & Environment

Colin McMillan

affiliation not provided to SSRN

Gregory A. Keoleian

University of Michigan at Ann Arbor

Date Written: October 2013

Abstract

Life cycle assessment practitioners struggle to accurately allocate environmental burdens of metals recycling, including the temporal dimension of environmental impacts. We analyze four approaches for calculating aluminum greenhouse gas emissions: the recycled content (RC) or cut‐off approach, which assumes that demand for recycled content displaces primary production; end‐of‐life recycling (EOLR), which assumes that postuse recycling displaces primary production; market‐based (MB) approaches, which estimate changes in supply and demand using price elasticities; and value‐corrected substitution (VCS), which allocates impact based on price differences between primary and recycled material. Our analysis suggests that applications of the VCS approach do not adequately account for the changing scrap to virgin material price ratio over time, whereas MB approaches do not address stock accumulation and depletion. The EOLR and RC approaches were analyzed using two case studies: U.S. aluminum beverage cans and vehicle engine blocks. These approaches produced similar results for beverage cans, which have a closed material loop system and a short product life. With longer product lifetimes, as noted with the engine blocks, the magnitude and timing of the emissions differs greatly between the RC and EOLR approaches. The EOLR approach indicates increased impacts at the time of production, offset by negative impacts in future years, whereas the RC approach assumes benefits to increased recycled content at the time of production. For vehicle engine blocks, emissions using EOLR are 140% higher than with RC. Results are highly sensitive to recycled content and future recycling rates, and the choice of allocation methods can have significant implications for life cycle studies.

Keywords: automobile, beverage cans, consequential LCA, industrial ecology, life cycle assessment (LCA), metals

Suggested Citation

Johnson, Jeremiah X. and McMillan, Colin and Keoleian, Gregory A., Evaluation of Life Cycle Assessment Recycling Allocation Methods (October 2013). Journal of Industrial Ecology, Vol. 17, Issue 5, pp. 700-711, 2013, Available at SSRN: https://ssrn.com/abstract=2339365 or http://dx.doi.org/10.1111/jiec.12050

Jeremiah X. Johnson (Contact Author)

University of Michigan at Ann Arbor - School of Natural Resources & Environment ( email )

440 Church St.
Ann Arbor, MI 48109
United States

Colin McMillan

affiliation not provided to SSRN

No Address Available

Gregory A. Keoleian

University of Michigan at Ann Arbor ( email )

500 S. State Street
Ann Arbor, MI 48109
United States

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