Corn-based ethanol alcohol mixed with gasoline, long a U.S. strategy to reduce greenhouse gas emissions from transportation, may be wrong-headed, according to a new research report to be published March 1, 2022 in the influential journal Proceedings of the National Academy of Sciences (PNAS).
The study by nine researchers led by Tyler J. Lark of the University of Wisconsin Madison, examining the US Renewable Fuel Standard, concluded, “The US Renewable Fuel Standard (RFS) is the world’s largest existing biofuel program, yet despite its prominence, there has been limited empirical assessment of the program’s environmental outcomes. Even without considering likely international land use effects, we find that the production of corn-based ethanol in the United States has failed to meet the policy’s own greenhouse gas emissions targets and negatively affected water quality, the area of land used for conservation, and other ecosystem processes. Our findings suggest that profound advances in technology and policy are still needed to achieve the intended environmental benefits of biofuel production and use.”
Ethanol production has been a major boon for America’s corn growers, as all gasoline sold in the U.S. has at least 10% ethanol (except for a limited amount of gasoline used in small gas-powered engines, where non-ethanol gas is often preferrable). It has given corn farmers a large new and lucrative market.
But lead author Lark told Reuters, “Corn ethanol is not a climate-friendly fuel.” Lark is at Wisconsin’s Center for Sustainability and the Global Environment.
Funded by the Department of Energy and the National Wildlife Foundation, the study found that ethanol is substantially more carbon-intensive than gasoline without alcohol, because of farming and land use practices incentivized by the RFS. The study said, “We find that the RFS increased corn prices by 30% and the prices of other crops by 20%, which, in turn, expanded US corn cultivation by 2.8 Mha (8.7%) and total cropland by 2.1 Mha (2.4%) in the years following policy enactment (2008 to 2016). These changes increased annual nationwide fertilizer use by 3 to 8%, increased water quality degradants by 3 to 5%, and caused enough domestic land use change emissions such that the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher.”
The Renewable Fuels Association, which represents ethanol producers in Washington, rejected the findings. Geoff Cooper, RFA chief, told Reuters that the study is “completely fictional and erroneous,” and used ‘worst-case assumptions [and] cherry-picked data.” A 2019 US Department of Agriculture found that carbon intensity of ethanol was 39% lower than gasoline alone, largely because of carbon sequestration with planting new corn crops.
The carbon sequestration concept has become controversial as some researchers claim its benefits are overstated.
–Kennedy Maize