Fact Checker: Is Joni Ernst right on ethanol? – The Gazette

U.S. Sen. Joni Ernst, a member of the Senate Committee on Agriculture, Nutrition and Forestry, questioned former Iowa Gov. Tom Vilsack at a Feb. 2 hearing on his nomination to be U.S. agriculture secretary.

The committee confirmed Vilsack, setting him up for approval by the full Senate. Vilsack also served as ag secretary during President Barack Obama’s administration.

Ernst wanted to know whether Vilsack will “stand firm” on the Renewable Fuel Standard, which mandates U.S. transportation fuels contain a minimum value of biofuel, which could be corn-based ethanol or cellulosic ethanol.

There is concern among Republicans, including Ernst, that Democratic President Joe Biden’s plan to convert the federal vehicle fleet to electricity will leave ethanol in the dust.

“As you know — you know this intimately — Iowa is a top producer of our biofuels, both ethanol and biodiesel,” Ernst said. “A new report released just last week found greenhouse gas emissions from corn ethanol are 46 percent lower than gasoline.”


The Fact Checker will check these statements, which are part of a larger conversation about the best ways to reduce carbon emissions to attempt to head off climate change. First, let’s check the statement about Iowa being a top producer of ethanol and biodiesel.

A 2018 report by the U.S. Energy Information Administration said Iowa is the top producing state for fuel ethanol with the capacity for up to 102 million barrels per year. The next highest state was Nebraska at more than 50 million barrels per year.

It makes sense Iowa, as the top corn producing state in the nation, would be a powerhouse for ethanol, which is made by fermenting the starches and sugars in grains, usually corn.

The Energy Information Administration reported last year Iowa has the largest biodiesel plant capacity in the country at more than 10 million barrels per year in 2019, or about 17 percent of the nation’s capacity. Texas was second place. Most U.S. biodiesel is made with soybean oil, which Iowa can supply as one of the nation’s top producers of soybeans.

For the first claim, Ernst gets an A.

In the second part of her statement, Ernst cites a new report, which is a manuscript accepted for publication in Environmental Research Papers, a peer-reviewed journal. The report, titled “Carbon intensity of corn ethanol in the United States: state of the science,” was written by four researchers, two from Harvard University, one from Tufts University and the principal investigator, Melissa Scully, from Environmental Health & Engineering Inc. in Newton, Mass.

The researchers reviewed well-to-wheel analyses of greenhouse gas emissions for corn ethanol. Well-to-wheel includes all emissions related to fuel production, processing, distribution and use. The team noted it updated its model to include changes on the farm to lower use of fertilizer and fossil fuels, more efficient use of natural gas at ethanol refineries and land use changes. The result is an estimate of carbon intensity for corn ethanol of 51.6 grams of carbon dioxide equivalent per megajoule of energy, which is 46 percent lower than the “average carbon intensity” of gasoline.

The largest component, 58 percent, of the carbon intensity computation is the production the ethanol at a refinery.

“Market conditions that favor greater adoption of precision agriculture systems, retention of soil organic carbon, and demand for co-products from ethanol production may lower the carbon intensity of corn ethanol further,” the report states.

A Canadian study published in October in the journal Renewable and Sustainable Energy Reviews found replacing gasoline with an ethanol blend in Canada’s light-duty vehicle fleet could reduce well-to-wheel greenhouse gas emissions in 2030 by 7.2 percent for corn and wheat ethanol. The report noted that reduction is less than one-fifth of the reductions Canada committed to in the Paris Agreement on climate.

Neither report compares ethanol’s carbon emissions with electric vehicles, but a report from the Alternative Fuels Data Center within the U.S. Department of Energy says well-to-wheel emissions of an all-electric vehicle produces about 4,000 pounds of carbon dioxide equivalent per year, compared with about 11,000 pounds for a gas-powered vehicle. This means the emissions for an electric vehicle were about 63 percent less than a gas-powered one.

While electric vehicles produce no carbon emissions themselves, the well-to-wheel analysis accounts for emissions at power plants that power charging stations and additional emissions that come from the process of extracting battery materials, such as lithium. As more states move away from coal-fired power plants, that will factor into reduced well-to-wheel emissions for electric vehicles.

We give Ernst an A for accurately citing a credible report about the potential for ethanol to reduce greenhouse gas emissions over gasoline.


Iowa has invested heavily in ethanol and biodiesel production, investments Ernst and other Iowa politicians are eager to protect. She is correct about Iowa’s prominence in the industry and accurately reports from the recent analysis showing corn ethanol produces 46 percent less greenhouse gas emissions than gasoline. The only missing context is that ethanol’s performance relative to electricity, which has a greater potential than ethanol to reduce greenhouse gas emissions.

As a side note, Vilsack said he sees a place for ethanol for the “foreseeable future,” especially as a greener alternative in U.S. ships and planes.

We give Ernst an A overall.


The Fact Checker team checks statements made by an Iowa political candidate/officeholder or a national candidate/officeholder about Iowa, or in ads that appear in our market.

Claims must be independently verifiable.

We give statements grades from A to F based on accuracy and context.

If you spot a claim you think needs checking, email us at factchecker@thegazette.com.

This Fact Checker was researched and written by Erin Jordan of The Gazette.

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