New bills raise debate over ethanol’s environmental impact, with implications for the climate

By: - November 10, 2023 4:58 pm
An ethanol plant near Aberdeen. (Joshua Haiar/South Dakota Searchlight)

An ethanol plant near Aberdeen. (Joshua Haiar/South Dakota Searchlight)

South Dakota’s congressional delegation wants the federal government to measure the environmental impact of biofuels in a way that some researchers say is unlikely to help mitigate climate change.

Sen. John Thune and Rep. Dusty Johnson, both Republicans, recently reintroduced similar bipartisan bills in the Senate and House, with Sen. Mike Rounds, R-South Dakota, cosponsoring the Senate legislation. The bills would require the Environmental Protection Agency to prioritize a particular model for assessing the environmental impact of biofuels.

“We should be using the best science available and that’s exactly what this bill does,” Johnson said in a press release.

Critics allege CO2 pipelines ‘farm the government’ for climate money while helping oil industry

The delegation wants the EPA to make the Greenhouse gases, Regulated Emissions, and Energy use in Transportation model — or GREET — the primary model for determining biofuel’s impact on the climate. That information would then be used by the EPA to help determine the volume of biofuels mandated to be mixed into the nation’s fuel supply, which is called the renewable fuel standard. 

The model was developed by Argonne National Laboratory for the U.S. Department of Energy and is already one of the models used to help inform the EPA’s renewable fuel standard. 

The bill’s supporters say biofuels are good for the environment.

“It’s past time for the EPA to update its greenhouse gas modeling for all biofuels, which would more accurately reflect the emissions reductions achieved by ethanol, biodiesel, and sustainable aviation fuel,” Thune said in a press release.

Biofuels industry leaders also support prioritizing the GREET model.

“It is a well-established and well-understood model that is regularly updated through a consensus, peer-reviewed approach,” said a statement from Erin Branick, of South Dakota-based Poet, the world’s largest biofuel producer. “The model is based solely on nonpartisan scientific analysis.”

The legislation is also supported by Gevo (a would-be South Dakota bio-aviation fuel producer), the National Corn Growers Association, the American Coalition for Ethanol, the Renewable Fuels Association and the National Oilseed Processors Association.

Other models

Meanwhile, Jason Hill, a bioenergy professor and researcher at the University of Minnesota, emphasized the need to use multiple models, “which is what the EPA is currently doing,” rather than relying primarily on the GREET model.

“That model doesn’t account for things like the economic repercussions of certain policies,” he said. “For example, how more fuel production lowers fuel prices, and people then use more fuel.”

The bills say that within 90 days of their passage, and then every five years, the EPA would be required to adopt the latest version of the GREET model.

The agency currently relies on several models to gauge the impacts of biofuels to determine the renewable fuel standard. Models include FASOM, which simulates biofuel policy impacts on agriculture; CARD, which examines biofuel policies’ effects on agricultural markets; the EPA’s MOVES model, which predicts emissions from mobile sources; and other land-use models that help evaluate biofuel production’s impact on land changes.

Silvia Secchi, an environmental impacts researcher and professor at the University of Iowa, said the GREET model overlooks the climate implications of crop production, particularly concerning land-use changes like converting grasslands to cropland to produce more corn and soybeans for biofuels. 

Branick, of Poet, pushed back on that assertion. 

“Land use change is often overestimated by some with an agenda,” Branick said. “The total acreage of land devoted to corn agriculture has remained unchanged for nearly a century, and to claim that bioethanol production increases land-use change is simply disconnected from reality.”

Statistics from the U.S. Department of Agriculture show corn acreage has risen steadily since the 1990s, from roughly 70 million acres to more than 90 million acres nationally, and from about 3 million acres to more than 6 million acres in South Dakota. Corn is the most widely grown crop in South Dakota, and most of it is sent to ethanol plants.

Hill recently co-authored a study examining farmers’ profits and the health and environmental costs of growing corn in the Midwest, where about 20% of the world’s corn is grown. It found that the health and environmental costs — like ammonia inhalation and water pollution — of current management practices are $25.6 billion per year, exceeding farmer profits, which averaged $4.3 billion per year from 2013 to 2022. Ammonia inhalation is related to ammonia-based fertilizers, which can also be washed during a rainfall event into wetlands, creeks and rivers.   

CO2 pipelines

Under the renewable fuel standard, fuels are evaluated using “carbon intensity” (CI) metrics, and GREET helps determine a biofuel’s CI score. Carbon dioxide is a greenhouse gas that contributes to climate change by trapping heat in the atmosphere.

To improve the CI score of ethanol, projects worth billions aim to build pipelines to trap carbon dioxide emissions from ethanol plants. The projects are eligible for tax credits from the federal government that are intended to incentivize underground carbon storage, known as sequestration.

Two such proposals in South Dakota have had their permits rejected by regulators due in part to landowner opposition, but one of the pipeline projects plans to reapply after adjusting its route.

Hill said carbon from the pipelines could also be used for enhanced oil recovery, promoting fossil fuel use. Carbon dioxide can be injected into aging oil wells, where it mixes with the oil underground, makes it less thick and helps it flow better. It also causes the oil to expand, pushing it toward the wells where it can be collected.

Hill said the federal tax credits for carbon sequestration could end up incentivizing more oil production if the GREET model becomes the “gold standard.”

“The model they want would give the projects tax credits for the CO2 being pumped underground, but overlook the environmental consequences of extracting more oil,” Hill said. He said any honest CI score would take that variable into account.

The remaining company proposing a carbon pipeline in South Dakota, Summit Carbon Solutions, says its project will not be used for oil recovery. But a company executive acknowledged during a regulatory hearing that the pipeline would be a common carrier, which means it could be used by other companies interested in transporting CO2 for oil recovery. Maps show the project’s sequestration site is near the oilfields of western North Dakota.

The Renewable Fuels Association has acknowledged that some carbon capture projects, due to their proximity to oil fields, could supply CO2 for enhanced oil recovery.

Neither the Senate nor the House bill requiring the EPA to prioritize the GREET model has had a committee hearing.



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Joshua Haiar
Joshua Haiar

Joshua Haiar is a reporter based in Sioux Falls. Born and raised in Mitchell, he joined the Navy as a public affairs specialist after high school and then earned a degree from the University of South Dakota. Prior to joining South Dakota Searchlight, Joshua worked for five years as a multimedia specialist and journalist with South Dakota Public Broadcasting.