Lark’s study comes at a decisive time for the future of corn ethanol. Later this year the EPA will decide how much biofuel should be blended into U.S. transportation fuel from 2023 onward. And on April 12 the White House temporarily waived the summertime ban on E15, fuel made from gasoline blended with between 10.5 percent and 15 percent ethanol. In the U.S., E15 is banned over the summer months because of the way it reacts with sunlight to create smog, but lobbyists and some lawmakers have argued that removing the ban will ease the country’s reliance on Russian oil and keep down gasoline prices. Earlier this month, Congress voted to ban imports of oil, gas, and coal from Russia.

Increasing corn ethanol production would be a big mistake, says Jason Hill, a biofuels expert at the University of Minnesota. “The science has long pointed out that this is not where we want to go,” he says. “In the long run corn ethanol has done almost nothing for our energy independence, and it has a large, disproportionately negative impact on the environment and food security.”