In light of recent action by the state of California to refine its ethanol greenhouse gas emission (GHG) calculations for the state’s Low Carbon Fuels Standard (LCFS), the U.S. Environmental Protection Agency (EPA) also should reevaluate its modeling of lifecycle GHG emissions under the Renewable Fuels Standard (RFS2), wrote the Renewable Fuels Association (RFA) in a letter to EPA Administrator Lisa Jackson.

At issue is EPA’s highly uncertain analysis of emissions from hypothetical indirect land use changes (ILUC) assumed to result from biofuels expansion under the RFS2. Recent analyses from Purdue University and the Department of Energy have demonstrated problems with the ILUC studies performed by the California Air Resources Board (CARB) and EPA for the recently implemented California LCFS and RFS2. In response to the new research, an Expert Workgroup appointed by CARB suggested changes and updates earlier this month to California’s LCFS modeling for ILUC related to ethanol. CARB has since adopted a resolution committing itself to implement the Expert Workgroup’s recommendations. Given that EPA was represented on the LCFS Workgroup and that it has publicly highlighted the fact that its ILUC results were similar to those originally obtained by CARB, the RFA is urging EPA to consider similar changes in its RFS2 calculations.

“The proposed changes to the California LCFS analysis are likely to result in substantially lower LUC values, meaning EPA’s analysis for the RFS2 will be inconsistent with the latest science being adopted by CARB. Because EPA was represented by two staff members on the LCFS Expert Workgroup that recommended the changes to CARB’s LUC analysis, we are curious as to whether EPA similarly plans to revisit its LUC analysis for the RFS2 and incorporate more up-to-date assumptions and data,” wrote RFA President and CEO Bob Dinneen in a letter dated November 23, 2010.

While EPA and CARB used different modeling approaches, some of the changes being adopted by CARB would result in lower values for ILUC in EPA’s RFS2 as well. Specifically, adjusted treatment of crop yields on newly converted land, treatment of carbon sequestration in harvested wood products, and the effect of higher prices on crop yields are among the factors that EPA should re-consider to ensure the RFS2 is based on the most up-to-date science and available data.

The RFA letter to EPA also served as a response to a September 29, 2010 response the RFA received from EPA in regard to concerns over RFS2 modeling approaches. The RFA has long argued that EPA’s isolation approach to calculating ILUC values for the various biofuels covered under the RFS2 ignores the dynamic relationships that exist between the fuels, the feedstocks, and in the marketplace. On August 4, 2010, the RFA wrote to EPA that “examining the impact of volume increases for individual biofuels in isolation of one another exaggerates the LUC impacts and misrepresents the real-world progression of the RFS2 as required by [the Energy Independence and Security Act].” Last week’s letter again encouraged EPA to consider an analytical method that examines the simultaneous and aggregate LUC effects of the RFS2.

According to RFA, the bottom line is that the science behind ILUC is still evolving rapidly and requires continual monitoring and updating to ensure the best available science is being appropriately considered.