I write to you in response to a recently released study by Tyler Lark, et al., from the University of Wisconsin-Madison and elsewhere that reviewed the environmental impacts of ethanol from corn. The authors claim this study was partially funded by the U.S. Department of Energy (DOE) and make significant and misleading errors in the study’s assumptions and conclusions. We urge the Department to correct the record on this study to ensure more widely accepted science is used to achieve our nation’s climate goals.
A wide range of agencies and researchers have reached positive environmental conclusions for corn-based ethanol, including the U.S. Department of Agriculture, the California Air Resources Board, and the Oregon Department of Environmental Quality. The DOE’s own Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies (GREET) model has been tracking corn-ethanol’s lifecycle analysis impacts since 1996, and has drawn starkly contrasting conclusions to the Lark study. Last May, DOE’s Argonne National Lab, which runs GREET, said “for the United States, biofuels like corn ethanol can play a critical role in reducing our carbon footprint.”
In its most recent iteration, GREET shows that corn ethanol has roughly 40
percent lower carbon emissions than traditional petroleum gasoline.5
“The greenhouse gas benefits of corn ethanol—assessing recent evidence,” Biofuels. Jan Lewandrowski, Jeffrey
Rosenfeld, Diana Pape, Tommy Hendrickson, Kirsten Jaglo, Katrin Moffroid (2020). 11:3, 361-375, DOI:
“Data Dashboard: Low Carbon Fuel Standard.” California Air Resources Board. May 2020.
“2021 Illustrative Compliance Scenarios.” ICF for the Oregon Department of Environmental Quality. July 2021.
“Corn ethanol reduces carbon footprint, greenhouse gases.” Argonne National Laboratory news release,
“Life-Cycle Greenhouse Gas Emission Reductions of Ethanol with the GREET Model”,
In addition, a January 2021 study by Environmental Health and Engineering, Inc. (EH&E) found
that ethanol reduces greenhouse gas (GHGs) emissions by 46%6
compared to traditional
gasoline. Improvements in ethanol’s carbon scores can be attributed to the related efficiencies in
land use and biorefineries. Corn growers are producing stronger yields with less acreage, and our
ethanol plants can obtain more gallons per bushel of corn. In fact, total cropland has fallen from
470.8 million acres of cropland in 1978 to 391.9 million acres by 20127
. Moreover, yields of
corn have increased dramatically over the last 50 years, increasing from 72.4 bushels per acre in
1970, to 172 bushels per acre in 2020. In the last 10 years, corn yields have increased by 20%,
while land planted for corn has remained steady.8
Unfortunately, the Lark study does not appropriately take these compelling scientific analyses
into account and uses non-public data sets to create incredibly high carbon penalties. A memo by
Pieter Booth, a principal with Net Gain Ecological Services, that provides a preliminary rebuttal
to the Lark study, is attached. Mr. Booth carefully examines many of the flaws in this study, but
this excerpt encapsulates many of his concerns:
“The authors characterize as fact numerous modeled results, giving the reader a
misleading impression of false confidence in the conclusions which are drawn from
highly uncertain models embedded with extensive assumptions that may or may not
reflect the real-world.”
Growth Energy specifically asks that DOE make clear that this research is both inconsistent with
and subordinate to the DOE’s GREET model, and that the Department did not specifically fund
this study, but instead, provided a grant related to the broader work of dedicated bio-energy
crops performed at the University of Wisconsin. Further, we ask the Department to evaluate if
this work violated the $115 million award provided by DOE to run from 2017-2022.
Failing to address this research’s inconsistencies and departure from mainstream science and
could have negative consequences in our nation’s quest to decarbonize the transportation
sector—both on the ground and in the air. According to recent research by the Rhodium Group9
our industry’s contributions in reaching net-zero emissions targets and decarbonizing the
transportation sector will be necessary. The ethanol industry is continually finding new ways to
innovate and reduce emissions throughout its production cycle, including by creating new
applications for hard-to-decarbonize industries like aviation. We must rely on the best and most
“Carbon Intensity of corn ethanol in the United States: State of the science,” Environmental Health & Engineering,
Inc.. Melissa Scully, Gregory Norris, Tania Alarcon Falconi, and David MacIntosh (March 2021).
“Cropland, 1945-2012, by State: The sum of cropland used for crops, cropland idled, and cropland used for
pasture,” U.S. Department of Agriculture’s Economic Research Service. August
“Crop Production Historical Track Records,” National Agricultural Statistics Service. April 2021,
“Closing the Transportation Emissions Gap with Clean Fuels.” The Rhodium Group,
widely accepted science to achieve our climate goals and attain net-zero emissions by 2050. The
Lark study is an off-base distraction from the work ahead of us.
Thank you for your attention in this matter and do not hesitate to reach out with any questions.