Sustainable Transportation Energy Pathways (STEPS)
Yeh, Sonia, Holly Gibbs, Steffen Mueller, Richard Nelson, Don O'Connor (2010) A Report to the California Air Resources Board: Carbon Emission Factors Subworkgroup, Low Carbon Fuel Standard (LCFS) Indirect Land Use Change Expert Workgroup. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-10-35
A key step of estimating the impacts of direct and indirect land use conversions as a result of increased biofuel demand is to estimate the amount and the duration of greenhouse gas (GHG) emissions as a result of land use and land use conversions in the various policy scenarios and the "base case" (i.e., no biofuel policy case). California Air Resources Board‘s (CARB) indirect land use change (ILUC) analysis for biofuels using the Global Trade Analysis Project (GTAP) model (CARB 2009) (CARB analysis hereafter) and a subsequent GTAP analysis by Tyner et al. (2010) (Tyner analysis hereafter) both characterize two kinds of emissions in their analyses: (1) carbon lost when forests or grasslands are cleared and converted into cropland, resulting in the loss of biomass and soil carbon stock; (2) foregone CO2 sequestration by the forest converted to crop land.
The purpose of this report is to critically review the assumptions used in the CARB and Tyner analyses and to make recommendations for improvements in CARB‘s future analyses. We recognize that some of the recommendations may require more time and resources; therefore they are broken into "must," "short-term," and "long-term" recommendations.
This report summarizes our findings of the literature review and recommendation for the calculation of emission factors for the analysis of indirect land use change (ILUC).