But some researchers in the field aren’t convinced the resource is nearly that big. Adam Liska at the University of Nebraska in Lincoln says a lot of this acreage is in the Great Plains, which wouldn’t produce a reliable crop year after year.

“One year you may have high rainfall and high crop yields and be able to sustain your facility, [but] the next year you may have a drought,” Liska says.

Indeed, Brent Erickson […] says nobody has plans just yet to use this kind of plant material to make biofuels. […]

“Every region of the country has some form of biomass — so the Northwest would have sawdust and wood waste; the California area might have rice straw or wheat straw, … Refiners in the Midwest are looking at corn cobs, and a plant that’s actually operating in Florida uses dead citrus trees.”

“As this technology progresses we’re going to see a great diversification of biomass supply,” Erickson predicts.

… Timothy Searchinger, an associate research scholar at Princeton University.

The 27 million acres identified in the latest study would provide less than 0.5 percent of our national energy demand, he says. And the more we try to expand biofuels, the more we risk displacing crops for food, or chopping down forests, which store a huge amount of carbon.

Searchinger says Europe has recently recognized those potential hazards and is scaling back its biofuels ambitions.

“They realize that it was a mistake, and their compromise for the moment is essentially to cap what they’re doing and then they promise by 2020 to phase out all government support for biofuels.”