A review of domestic land use change attributable to U.S. biofuel policy
Improving estimates of the quantity and location of land use change (LUC) attributable to U.S. biofuel policy, and specifically the Renewable Fuel Standard (RFS) program, is critical for comprehensive evaluation of impacts on air and water quality, biodiversity, soil quality and invasive species (EPA 2018). We review 29 studies published since 2008 attributing domestic LUC to the RFS program, updating previous comparisons of economic modelling approaches, and including a growing number of empirical approaches to estimating biofuel-induced LUC. We documented key attributes of each studies’ approach, including spatial extent and resolution, time period, baseline scenario, influence or treatment, biofuel feedstocks, and types of LUC examined. Although the diversity of approaches prevents a direct comparison, this synthesis allowed us to identify some of the principal reasons underlying the differences in reported effects. Economic modelling studies reported 0.01 to 14.6 million acres of additional cropland relative to a baseline in the absence of the simulated RFS Program (median: 3.95). Adjusting for differences in the magnitude of the modelled policy shock, this corresponds to a range of 0.01 – 2.45 million acres of net cropland expansion per billion-gallon increase in biofuel volumes (median: 0.41). Empirical approaches reporting national-scale estimates fall within this range, reporting 2.1 – 7.0 million acres of additional cropland, corresponding to 0.43 – 0.66 million acres per billion-gallon increase. Across approaches, studies generally did not represent all of the potential drivers of biofuel production, and instead reported projections reflecting a combination of RFS program impacts and other influences. Our best estimate of the historical effects of the RFS Program is a net increase of 1.1 – 7.0 million acres of cropland nationally, acknowledging that this range still reflects underlying differences in study design, assumptions, and time periods of investigation. Refinements to the approaches reviewed in this study will strengthen the evidence-base for sustainable biofuel policy in the future.