New study finds ethanol is worse than gasoline for climate, contradicting previous research

Source: By Donnelle Eller, Des Moines Register • Posted: Tuesday, February 22, 2022

A new study says ethanol is worse for the environment than gasoline, challenging the findings of other recent studies assessing renewable fuels’ greenhouse gas emissions.

The University of Wisconsin-Madison study, published in last week’sProceedings of the National Academy of Sciences, says a federal mandate requiring that ethanol be blended into the nation’s fuel supply has driven more intense corn cultivation and added acreage. The result: an increase in emissions related to land use and an overall carbon intensity for ethanol production that is “no less than gasoline and likely at least 24% higher.”

Both hailed as a critical look at biofuels’ “disastrous impact” on climate and criticized as “untethered from reality,” the study contradicts earlier research papers. They include a Harvard University study, published a year ago in Environmental Research Letters, finding that corn-based ethanol had 46% fewer net greenhouse gas emissions than gasoline.

A U.S. Department of Agriculture study published in 2019 drew a similar conclusion, finding that ethanol has 39%-43% lower carbon emissions than gasoline.

The newest research comes as Congress debates the need for the Renewable Fuel Standard, or RFS, a law passed in 2005 and expanded two years later. Aimed at cutting greenhouse gas emissions and reducing the nation’s reliance on foreign oil, it mandates that renewable fuels must be blended with gasoline, meaning that almost all gas sold in the U.S. contains 10% ethanol.

After 2022, the law no longer will require the U.S. Environmental Protection Agency to set the levels for the standard, raising doubt about the future of the RFS.

It’s seen as a critical economic issue for Iowa, the national leader in ethanol production, which absorbs half of the state’s annual corn crop — also the nation’s largest. The industry supports thousands of jobs in rural cities and towns across the state.

In addition, three companies are seeking to build multi-billion-dollar pipelines in Iowa to capture carbon dioxide emissions at ethanol and other agricultural plants. The greenhouse gas would be liquefied and sent to underground sequestration sites in a bid to help the industries dramatically reduce their carbon footprints.

Scientist says his study used a better model than previous ones

The new Wisconsin study says corn-based ethanol has failed to meet the country’s greenhouse gas emissions targets, raising questions about whether the biofuel should be part of its approach to addressing climate change.

President Joe Biden is pushing the nation toward electric vehicles to reduce carbon emissions, saying he wants half of all cars sold by 2030 to be electric.

In a statement on the study, David DeGennaro, a climate and biofuel specialist at the National Wildlife Federation,  pointed to an unintended environmental effect from U.S. reliance on ethanol.

“Rather than replace fossil fuels with a cleaner option, corn ethanol and the Renewable Fuel Standard have only accelerated the climate crisis, contaminated drinking water … and destroyed millions of acres of wildlife habitat,” said DeGennaro.

But Emily Skor, CEO of Growth Energy, a Washington, D.C., ethanol lobbying group,  attacked the study, saying it manipulated “science and data” and used “an unorthodox methodology that leads to really fictitious and erroneous conclusions.”

“In short, you’ve got a piece of work that’s untethered from reality,” Skor told a U.S. Senate committee examining the RFS last week. She added that the study contradicts “a totality of science,” including studies from EPA, the U.S. Energy Department’s Argonne National Laboratory and low-carbon fuel assessments by the states of California and Oregon.

“Ethanol is lower carbon than gasoline, and that advantage continues to increase,” Skor said.

Tyler Lark, a University of Wisconsin scientist who is the study’s lead author, said his team’s model is better than those used by previous studies to assess greenhouse gas emissions from land used to grow corn. “They are several different versions … of really just one estimate or approach,” Lark said.

The RFS requires that conventional or corn-based ethanol have at least 20% fewer greenhouse gas emissions than gasoline. To determine that, scientists assess emissions from each stage of production, from the field to the ethanol plant to the vehicle exhaust pipe.

The life-cycle analysis looks at what kind of crops are grown and how; land use changes; and the energy ethanol plants use, among other issues.

Switching from cotton and wheat to corn and soybeans

The study also looked at the RFS’ impact on crop prices and the mandate’s environmental costs.

The report says the RFS boosted corn prices 30% and soybean and wheat prices 20% from 2008 to 2016, prompting farmers to raise more corn. Lark said farmers grew corn more intensely on 6.9 million acres of existing cropland and planted crops on 5 million acres that was previously pasture or in conservation reserve programs.

Most of the newly cultivated acres were in North and South Dakota, western Minnesota and parts of Arkansas and Louisiana, the study said.

The push to grow more corn drove fertilizer use up 3%-8% and increased “water quality degradants,” such as nitrates leaching from fields, phosphorus runoff and soil erosion, by 3%-5%, the study said.

Geoff Cooper, the Renewable Fuels Association’s president, said farmers have shifted from crops like cotton in the South and wheat in the North to corn and soybeans. But he took issue with the finding that they had expanded acreage, saying “farmers aren’t plowing up millions of acres of native grassland and cutting down forests so they can plant more corn and soybeans.”

“And to say that plowing up that land, which didn’t happen, released lots of carbon and made ethanol no better than gas, it’s absurd,” Cooper said in a video, adding that total land used in farming has declined by about 25 million acres since the Renewable Fuel Standard was expanded in 2007.

“The corn we’ve needed to expand ethanol production has come from yield increases and yes, there has been some crop-switching acres,” he said.

Last year, the Argonne laboratory said that increased corn yields without extra fertilizer use resulted in a decreased amount of fertilizer per bushel of corn harvested. Along with more energy efficiency in ethanol production, it pushed the biofuel’s carbon intensity 23% lower than gasoline’s from 2005 to 2019.

Overall, the Argonne study said, ethanol reduced greenhouse gas emissions by about 540 million metric tons over 15 years.

But Jeremy Martin, director of the Union of Concerned Scientists’ fuel policy, said the Wisconsin study reached a different conclusion because it took into account how land would have been used had the federal biofuels policy not been implemented.

“This highlights what would have happened had we taken a different course a decade ago, and kept more land conservation cover,” Martin said. “The Midwest would have looked different. And it would have had implications for fertilizer use, for soil carbon, for water pollution.”

MORE: Iowa closes the books on once-promising renewable fuels plant in Emmetsburg; no repayment required

At a climate crossroads, the nation should move to more advanced ethanol, such as biofuel produced from more environmentally friendly perennial grasses such as miscanthus and switchgrass, Lark said.

“What we hoped could potentially be an environmental and climate solution in corn ethanol has come with quite a few environmental costs,” Lark said. “If anything, it really adds urgency to finding true climate solutions.”

 But at last week’s committee hearing on the Renewable Fuel Standard, U.S. Sen. Joni Ernst, an Iowa Republican, pointed to another benefit of ethanol and biodiesel production: creating jobs in rural America.

“The biofuels industry accounts for over $5 billion of GDP (gross domestic product), generates $2.6 billion of income for households and supports nearly 46,000 jobs in Iowa alone. In my rural area,” she said.

Ernst criticized Biden’s push toward electric vehicles.

“As much as the Biden administration dreams of an all-electric world, the reality is liquid fuels are here to stay,” Ernst said. “With 98% of cars and trucks today, and nearly 80% of new vehicle sales projected in 2050 running on gasoline or flex fuel, biofuel is the key pathway to decarbonizing the transportation sector — and the RFS is the policy engine that makes this possible.”

The University of Wisconsin study was funded in part by the National Wildlife Federation, the Great Lakes Bioenergy Research Center at the UW-M, and U.S. Department of Energy.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at or 515-284-8457.