Corn Based Ethanol Worse for Climate than Gasoline

February 14, 2022


Corn-based ethanol, which for years has been mixed in huge quantities into gasoline sold at U.S. pumps, is likely a much bigger contributor to global warming than straight gasoline, according to a study published Monday.

The study, published in the Proceedings of the National Academy of Sciences, contradicts previous research commissioned by the U.S. Department of Agriculture (USDA) showing ethanol and other biofuels to be relatively green.

President Joe Biden’s administration is reviewing policies on biofuels as part of a broader effort to decarbonize the U.S. economy by 2050 to fight climate change.

“Corn ethanol is not a climate-friendly fuel,” said Dr. Tyler Lark, assistant scientist at University of Wisconsin-Madison Center for Sustainability and the Global Environment and lead author of the study.

The research, which was funded in part by the National Wildlife Federation and U.S. Department of Energy, found that ethanol is likely at least 24% more carbon-intensive than gasoline due to emissions resulting from land use changes to grow corn, along with processing and combustion.

Geoff Cooper, president and CEO of the Renewable Fuels Association, the ethanol trade lobby, called the study “completely fictional and erroneous,” arguing the authors used “worst-case assumptions [and] cherry-picked data.”

Under the U.S. Renewable Fuel Standard (RFS), a law enacted in 2005, the nation’s oil refiners are required to mix some 15 billion gallons of corn-based ethanol into the nation’s gasoline annually. The policy was intended to reduce emissions, support farmers, and cut U.S. dependence on energy imports.

As a result of the mandate, corn cultivation grew 8.7% and expanded into 6.9 million additional acres of land between 2008 and 2016, the study found. That led to widespread changes in land use, including the tilling of cropland that would otherwise have been retired or enrolled in conservation programs and the planting of existing cropland with more corn, the study found.

Tilling fields releases carbon stored in soil, while other farming activities, like applying nitrogen fertilizers, also produce emissions.

A 2019 study from the USDA, which has been broadly cited by the biofuel industry, found that ethanol’s carbon intensity was 39% lower than gasoline, in part because of carbon sequestration associated with planting new cropland.

But that research underestimated the emissions impact of land conversion, Lark said.

USDA did not respond to a request for comment.

The U.S. Environmental Protection Agency, which administers the nation’s biofuel policy, is considering changes to the program. Under the RFS, Congress set blending requirements through 2022, but not beyond, giving the EPA authority to impose reforms. EPA plans to propose 2023 requirements in May.

6 Responses to “Corn Based Ethanol Worse for Climate than Gasoline”

  1. mboli Says:

    Meanwhile, two companies in Illinois announced a project to build a factory producing 120 million gallons yearly of aviation biofuel.

    They claim it will be 70% less carbon polluting than the regular stuff, based on using corn ethanol and also utilizing carbon capture and storage.

    One wonders how this new analysis would change that claim.

    Here is a typical article. (The articles are all the same, it seems they came from a press release.)

    • rhymeswithgoalie Says:

      “Biofuel” covers a range of potential sources and technologies. Growing corn straight up just to make ethanol to burn sounds goofy, but there may be some waste-stream sources where the cost/benefit calculation changes.

      • renewableguy Says:

        Saw a film on restorative farming. More like turning the farm into an intentional prairie. Cattle eat the different grasses and plants, manure fertilizing the plants and the prarie returning carbon to the soil. Fantastic.

  2. renewableguy Says:

    My uncle grows corn on the Iowa border in Illinois. Clinton Iowa has an ethanol facility along the Mississippi. I noticed a really large round gold ball outside the facility. Turns out that gold ball holds coal. Wow. Just disappointing. Enuff said.

  3. indy222 Says:

    You mean they LIED to us?! Say it ain’t so, Joe!

    Yes, this finding is not new, nor is the Greenwash new.

  4. Gingerbaker Says:

    On the other hand, at least the grassland is being converted to arable farming. You don’t HAVE to grow corn there, and there will be increasing demands for ag exports over the next century.

    If that arable farmland can be managed correctly, the soil could be a carbon sink.

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