Ethanol no better than gasoline, study finds

Though popular with Midwestern farmers and long hailed as an environmentally friendly alternative to imported oil, ethanol made from corn isn’t actually reducing greenhouse gas emissions, a new study finds.

But UW-Madison researchers say there are home-grown alternatives being developed at laboratories in Madison.

Corn-based ethanol, which accounts for virtually all US biofuels, doesn’t really reduce greenhouse gas emissions and is likely making climate change even worse than simply burning fossil fuels, according to the paper published last week in the Proceedings of the National Academy of Sciences.

While not surprising to some scientists, the findings represent the first empirical analysis of the nation’s 15-year-old renewable fuel mandate and could inform debates over which types of alternative fuels should be favored going forward.

Instead, the authors suggest, the government should encourage the use of fuels derived from non-food plants like grasses that trap carbon in the ground, keep topsoils in place and don’t require chemical fertilizers.

“It basically reaffirms what many suspected,” said Tyler Lark, a scientist at UW-Madison’s Great Lakes Bioenergy Research Center and lead author of the paper. “Corn ethanol is not a climate-friendly fuel, and we need to accelerate the shift toward better renewable fuels.” First enacted by Congress in 2005 and expanded in 2007 in an effort to reduce greenhouse gas emissions and reliance on imported oil, the Renewable Fuel Standard requires transportation fuel to contain a minimum amount of renewable fuel.

While the law calls for increasing use of “advanced” biofuels, nearly all the renewable fuel used is corn-based ethanol, which the Environmental Protection Agency has estimated to reduce greenhouse gas emissions by 20% compared with gasoline.

This is the final year in which the Renewable Fuel Standard spells out specific biofuel volumes. Going forward, the EPA will take over the role of determining how much and which types of biofuels are needed.

“It’s a pivotal moment for deciding what this policy — and our landscape — should look like moving forward,” Lark said.

About five years ago, Lark and UW-Madison geographer Holly Gibbs assembled a team of economists, agronomists and other researchers to evaluate the accuracy of the EPA’s carbon footprint estimates.

“It’s really the first time we’ve taken a retrospective empirical analysis,” Lark said. “We were more clearly able to estimate what happened versus what would have happened.”

What they found is that in the 15 years since it was adopted, the renewable fuel standard boosted corn prices by about 30%, leading farmers to plant more corn — often on pasture and other marginal lands — and apply more fertilizer than they would have without an ethanol mandate.

The carbon released by these landscape changes offset any reduction in tailpipe emissions and may actually produce more greenhouse gasses than simply burning fossil fuels. And that doesn’t include the upstream carbon emissions that come from making more fertilizers.

“Any time you plow up a perennial grassland that’s sequestering carbon on the landscape … you emit a lot of carbon from the soil back into the atmosphere,” Lark said. “Those emissions, when accounted for, have a really big role in offsetting the net benefits of ethanol.”

Ethanol trade groups called the findings “completely fictional and erroneous” while pointing to a disputed industry-funded study that concluded ethanol has less than half the carbon intensity of gasoline.

“It is so disappointing that our own land grant university can miss the mark so badly,” said Erik Huschitt, president of the Wisconsin Biofuels Association.

Make way for corn

Industry groups note that total U.S. cropland has actually decreased since the passage of the ethanol mandate, which the American Corn Growers Association falsely claims invalidates the findings.

But both can be true: Even as some fields were lost to urban sprawl, farmers were also plowing up grassland, releasing carbon into the atmosphere.

“What’s important for folks to consider is what would have happened in the absence of corn ethanol development and the renewable fuel standard,” Lark said.

Lark’s team found almost 5 million acres of natural lands were brought back into production between 2008 and 2016, and farmers planted about 7 million more acres of corn than would be expected without the economic pressures created by the ethanol mandate.

 And the impacts weren’t just limited to the atmosphere.

Those additional acres of corn required 8% more fertilizer, which led to more phosphorus washed off the land, contributing to algal blooms and aquatic dead zones, and more nitrate seeping into groundwater.

The Wisconsin Department of Health Services estimates at least one in 10 private wells has high levels of nitrate, which is hazardous, especially to pregnant women and infants.

And while the ethanol mandate boosted corn prices, Lark said that has also resulted in higher feed and rental costs for dairy farmers.

“What might be good for one commodity crop and interest group often comes at a cost for others,” Lark said. “It’s often the largest agribusinesses that are able to take advantage and the smaller ones that get squeezed out.”

The past two decades have been the warmest on record, and the 2010s the wettest, with sharp increases in extreme storms that lead to loss of life, property and agricultural production.

‘Next generation’ biofuels

Lark argues that to achieve true reductions in greenhouse gas emissions, the renewable fuel standard should encourage development of “next generation biofuels” made from native grasses and other non-food plants grown on land less suited for conventional agriculture.

Hundreds of researchers at the Great Lakes Bioenergy Research Center in Madison are working to make that possible.

Established in 2007 with funding from the U.S. Department of Energy, the GLBRC is an interdisciplinary research center focused on economically viable and environmentally sustainable biofuels and other products.

Linda Horianopoulos, a postdoctoral fellow at the Great Lakes Bioenergy Research Center, experiments with different species of yeast used to ferment plant-based sugars into alternatives to fossil fuels and corn-based ethanol.

Researchers at the center are working to develop ways of turning plants like switchgrass, sorghum and poplar into alcohol-based chemicals that can fuel car, truck and airplane engines as well as be converted into products like plastic and nylon that are currently derived from petroleum.

“We’re using energy crops — crops that you would grow specifically to make transportation fuels and chemicals,” said Tim Donohue, a microbiologist who directs the center. “These crops are not being grown on acreage that’s currently used to produce food.”

With deep root systems, native grasses are able to hold soil in place and actually suck carbon from the air and trap it underground. And because they are perennial, once established a crop doesn’t have to be replanted and fertilized every year.

The center has generated hundreds of patents and licenses and spun off five startup companies, including the Madison-based Virent, whose plant-based fuel recently powered a commercial airline test flight.

But Donohue said commercial-scale production could be at least five years off because advanced biofuel refineries can cost as much as $400 million to build.

Sugar extracted from plant biomass used for fuel production in the lab at the Great Lakes Bioenergy Research Center at the Wisconsin Energy Institute in Madison.

Despite its unintended consequences, Lark said the Renewable Fuel Standard demonstrated that it’s possible to replace petroleum with plant-based fuels, setting the stage for more environmentally friendly replacements.

“Corn ethanol was a technology that was ready, initially, and probably filled a good role as an example of how we could get a renewable fuel blended into our transportation fuel supply,” Lark said. “That really can set an example of how we can use these next-generation fuels and other alternatives that are more climate-friendly.”


Tags: Biofuels, Corn-based, Ethanol, Gasoline, UW-Madison
Share with your friends