Accounting for indirect land-use change in the life cycle assessment of biofuel supply chains
Accepted for publication in J. R. Soc. Interface 9 (2012); doi: 10.1098/rsif.2011.0769 Copyright © 2012 The Royal Society. Used by permission.
Submitted November 9, 2011; accepted March 2, 2012.
The expansion of land used for crop production causes variable direct and indirect greenhouse gas emissions; and other economic, social and environmental effects. We analyze the use of life cycle analysis (LCA) for estimating the carbon intensity of biofuel production from indirect land-use change (ILUC). Two approaches are critiqued; direct, attributional life cycle analysis (ALCA) and consequential life cycle analysis (CLCA). A proposed hybrid “combined model” of the two approaches for ILUC analysis relies on first defining the system boundary of the resulting full LCA. Choices are then made as to the modeling methodology (economic equilibrium or cause-effect), data inputs, land area analysis, carbon stock accounting and uncertainty analysis to be included. We conclude that CLCA is applicable for estimating the historic emissions from ILUC, although improvements to the hybrid approach proposed, coupled with regular updating, are required, and uncertainly values must be adequately represented; however, the scope and the depth of the expansion of the system boundaries required for CLCA remain controversial. In addition, robust prediction, monitoring and accounting frameworks for the dynamic and highly uncertain nature of future crop yields and the effectiveness of policies to reduce deforestation and encourage afforestation, remains elusive. Finally, establishing compatible and comparable accounting frameworks for ILUC between the USA, EU, southeast Asia, Africa, Brazil and other major biofuel trading blocs, is urgently needed if substantial distortions between these markets which would reduce its application in policy outcomes are to be avoided.