EH&E Response to Proposed Renewable Fuel Standard (RFS) Program Standards for 2023–2025

We at Environmental Health & Engineering (EH&E) are a multi-disciplinary team of environmental health scientists and engineers with expertise in measurements, models, data science, lifecycle analyses (LCA), and public health. Members of our team conducted a state of the science review of the carbon intensity (CI) for corn ethanol in the United States (U.S.), as well as a reply supporting our work and a comprehensive assessment of the impacts of corn ethanol fuel blends on tailpipe emissions. A primary conclusion from our past and present work is that the best available science suggests a well-to-wheel corn starch ethanol CI of 51 gCO2e/MJ, representing an approximately 46% reduction in GHG emissions relative to the petroleum gasoline baseline. Over the past several months, we have submitted public comments to governmental agencies including EPA and the State of Washington. We have also recently published a reply that shares feedback on a recent but questionable study of domestic land use change. A theme present across all of our analyses is that, overall, the CI estimates for the indirect land use change (iLUC) associated with corn starch ethanol have been converging on
lower values when considering the best available science and improved models. The latest analyses of the four commonly relied upon models—GTAP-BIO, FAPRI-CARD, MIRAGE, and GLOBIOM—show results that are 2-fold to 4-fold lower than the results from studies that use outdated models. Studies that do not incorporate the best available science suggest a strong link between biofuel expansion and iLUC; as we will discuss, recent empirical research does not support that relationship.

We submit this letter to EPA in response to the proposed Renewable Fuel Standard (RFS) Program: Standards for 2023–2025 and Other Changes (hereafter, “the Set Proposal”) and the associated Draft Regulatory Impact Analysis (DRIA).