Do emerging guidelines for automotive life cycle assessment lead to consistent results? The case of battery electric vehicles

Abstract

Road transportation is responsible for one fifth of European Union’'s total greenhouse gases (GHGs), besides other environmental concerns. Thus, Life Cycle Assessment (LCA) is increasingly used in the automotive sector to guide environmental strategies and policy compliance, emphasizing the importance of methodological choices and their standardization. This study examines three recent and influential LCA guidelines in Europe developed through major harmonization initiatives: TranSensus LCA, Catena-X, and the United Nations Economic Commission for Europe Automotive LCA guidelines. A qualitative comparison of methodological choices and assumptions in these guidelines was conducted to identify areas of overlap, divergences, and flexibilities within each guideline. The analysis showed broad alignment across guidelines, with divergences mainly in electricity modeling and addressing multifunctionality problems, where also degrees of freedom within guidelines remain. Applied to a battery electric vehicle LCA, a quantitative comparison across guidelines (based on a basic expected application of each guideline) demonstrated less than a 10 % difference in most impact categories. Furthermore, the intra-guideline choices (flexibilities) were tested in the LCA model, showing larger variations relative to the basic application of each guideline (e.g., −27 % and +11 % change in climate change impacts when shifting to the Circular Footprint Formula (CFF) and static electricity modeling, respectively, in UNECE guidelines). These findings suggest that horizontal harmonization across guidelines is well advanced, but vertical harmonization within guidelines requires improvement. Future improvements could include more detailed guidance in some parts like CFF application to reduce subjectivity, automation of application, and comprehensiveness in impact categories and life cycle stages coverage.