Researchers say the U.S. government has set biofuels production targets that mean American consumers will have to choose between environmentally friendly fuel and eating domestically produced food.

William Kolby Smith, a doctoral candidate at the University of Montana, says almost 80% of existing U.S. farmland would have to be devoted to raising corn for ethanol production to meet current biofuels production objectives with existing technology.

An alternative, Smith says in a study published in the American Chemical Society’s Environmental Science & Technology journal, would be to convert 60% of existing rangeland to biofuels.

Smith and fellow researchers say the 2007 Energy Independence and Security Act set a goal of increasing annual U.S. biofuels production from the current 10.6 billion gallons (41 billion L) to 35.9 billion gallons (136.7 billion L) of ethanol by 2022.

The research team says gaps exist in the ability to establish realistic targets for biofuels production, while the law contains assumptions about technological developments and the availability and productivity of farmland.

In an effort to establish more accurate estimates, the team used satellite data regarding climate, plant cover and usable land to determine how much biofuels the U.S. could produce.

The satellite analysis found that while the energy targets specified in the law are theoretically achievable, meeting those goals utilizing current technology would require either an 80% displacement of current crop harvest or the conversion of 60% of rangeland productivity.

They say either option not only would significantly reduce the amount of food U.S. farmers produce, but also lead to more polluted freshwater and accelerate global climate change.

“Accordingly, energy planning should include iteratively and realistically constrained bioenergy estimates for effective incorporation of bioenergy potential into the national energy portfolio,” the report concludes.