the Corn Belt is on the move. Over the past couple of decades, farmland devoted to corn production has been creeping northward and westward. In North and South Dakota, grasslands that were formerly used for cattle grazing or set aside for conservation have been converted to cornfields. Between 2005 and 2021, the area of land harvested for corn in the U.S. increased by around 14 percent.
One of the big drivers of this shift has been bioethanol—transportation fuel usually made from fermented corn. Since 2005, the U.S. government’s Renewable Fuel Standard has mandated that gasoline producers blend corn ethanol into their fuel. The amount the RFS requires to be mixed in has ratcheted up each year from the policy’s start, and since 2016 gasoline producers have been instructed to blend 15 billion gallons of corn ethanol annually into transportation fuel. The RFS was supposed to reduce reliance on fuel imports and lessen the environmental impact of the transportation sector, but when it was introduced some scientists warned that it might end up increasing overall emissions. Now it looks like those predictions have come to pass.
In February, Tyler Lark, a scientist at the University of Wisconsin–Madison, published a study analyzing the impact of the RFS. Lark and his colleagues researched the impact the policy had on crop prices and farm expansion between 2008 and 2016, comparing the real-world situation with a counterfactual one where biofuel production was kept at levels mandated in an earlier version of the RFS.
Lark’s study found that the RFS significantly pushed up the price of corn. This incentivized the expansion of total U.S. cropland by 2.1 million hectares between 2008 and 2016—an increase of 2.4 percent. Often the areas newly converted to cropland were grasslands on the western edge of the Corn Belt. “Over millennia these grasslands have created really carbon-rich soils. And what happens is, when you plow that up, you expose a lot of it and make it vulnerable to being released into the atmosphere,” says Lark.
The supposed benefit of biofuel is that, although it still releases carbon dioxide when it burns, that carbon was drawn down from the atmosphere by the plants that make up the fuel rather than being released from oil that was once underground. But growing fuel creates emissions too. The biggest problem is when land that used to be a carbon sink is plowed up to plant crops, but manufacturing fertilizer is also a major source of emissions, and applying that fertilizer to land also releases greenhouse gasses in the form of nitrous oxide emissions.
In 2010 the Environmental Protection Agency, which sets the amount of corn ethanol required by the RFS, estimated that by 2022 corn ethanol would have total life-cycle emissions 20 percent lower than gasoline. But these projections didn’t account for the dramatic effect the RFS would have on land use in the U.S. “I don’t think people expected as much land to come back into production,” says Lark. His study found that the RFS increased corn prices by 30 percent and the prices of other crops by 20 percent. In response, farmers who previously used their land for cattle grazing or were involved in conservation schemes started growing crops instead. All this land use change has essentially outweighed the reductions in greenhouse gas emissions that come from growing fuel instead of pumping it out of oil wells.
I yield to no man in my disdain for gasahol. It takes uses ground that that could be growing food for people, or at least food for our food (animals), instead of being wasted as a vehicle fuel for which it doesn't even serve the proclaimed function of reducing greenhouse gases. And the fuel isn't even very good, less energy dense than gasoline, and prone to water absorption problems. But it is a bi-partisan folly.