Earlier in 2017, the United States Department of Agriculture published a study undertaken by the consultants ICF International that included a reassessment of the lifecycle greenhouse gas intensity of corn ethanol. The report concluded that corn ethanol’s greenhouse gas intensity is already lower than the level projected for 2022 by the Environmental Protection Agency in the regulatory impact analysis for the Renewable Fuel Standard 2, a conclusion that has been embraced by advocates for the corn ethanol industry.
In this study, commissioned by the Clean Air Task Force and National Wildlife Federation, we provide a critical review of the ICF report. We find that the report shows a lack of balance, systematically emphasising evidence that could suggest that the performance of corn ethanol is better than previously modeled, while understating or ignoring conflicting evidence. More problematic even than this lack of balance, however, we find that the analysis in the report is riddled with errors of methodology and data, many of them at the most basic level, so as to render some of the results presented essentially meaningless. Given the many issues identified, we conclude that the work presented is wholly inadequate to justify any firm conclusion on whether the corn ethanol emissions estimates made by EPA could or should be revised down.