Attributional and Consequential Life-cycle Assessment in Biofuels: a Review of Recent Literature in the Context of System Boundaries

Abstract

At the core of the debate over life-cycle assessment (LCA) modeling of the environmental impacts of biofuels is doubt that biofuels can mitigate climate change. Two types of LCA, attributional and consequential, have been applied to answer this question with competing results. These results turn on system boundary design, including feedstock considerations and assumptions of indirect land-use impacts. The broadening of the system boundary to include large scale land-use change of biofuel production has challenged the viability of biofuels to meet climate change goals. This paper reviews some of the latest literature in biofuels LCA exemplary of this debate and discusses the distinctions between attributional and consequential models in biofuels. We also present a generalized boundary map that can be used to convey LCA system boundaries clearly and succinctly within both attributional and consequential LCA.