Almost 80 percent of current farmland in the U.S. would have to be devoted to raising corn for ethanol production in order to meet current biofuel production targets with existing technology, a new study has found.

An alternative, according to a study in ACS' journal Environmental Science and Technology, would be to convert 60 percent of existing rangeland to biofuels.

W. Kolby Smith and colleagues explain that the 2007 Energy Independence and Security Act (EISA) set a goal of increasing U.S. biofuel production from 40 to 136 billion gallons of ethanol per year by 2022.

They point out, however, that gaps exist in the ability to establish realistic targets for biofuel production, which the law fills with assumptions about technological developments and the availability and productivity of farmland.

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

The satellite analysis found that to meet the EISA goals under current technology, farmers would either need to plant biofuel crops on 80 percent of their farmed land or plant biofuel crops on 60 percent of the land currently used to raise livestock.

The authors reported that both options would significantly reduce the amount of food U.S. farmers produce. They also noted that research shows that increased farming could lead to more polluted freshwater and accelerate global climate change.