But the ethanol era has proven far more damaging to the environment than politicians promised and much worse than the government admits today.
As farmers rushed to find new places to plant corn, they wiped out millions of acres of conservation land, destroyed habitat and polluted water supplies, an Associated Press investigation found.
Five million acres of land set aside for conservation — more than Yellowstone, Everglades and Yosemite National Parks combined — have vanished on Obama's watch.
Landowners filled in wetlands. They plowed into pristine prairies, releasing carbon dioxide that had been locked in the soil.
Sprayers pumped out billions of pounds of fertilizer, some of which seeped into drinking water, contaminated rivers and worsened the huge dead zone in the Gulf of Mexico where marine life can't survive.
The consequences are so severe that environmentalists and many scientists have now rejected corn-based ethanol as bad environmental policy. But the Obama administration stands by it, highlighting its benefits to the farming industry rather than any negative impact.
Farmers planted 15 million more acres of corn last year than before the ethanol boom, and the effects are visible in places like south central Iowa.
The hilly, once-grassy landscape is made up of fragile soil that, unlike the earth in the rest of the state, is poorly suited for corn. Nevertheless, it has yielded to America's demand for it.
"They're raping the land," said Bill Alley, a member of the board of supervisors in Wayne County, which now bears little resemblance to the rolling cow pastures shown in postcards sold at a Corydon pharmacy.
All energy comes at a cost. The environmental consequences of drilling for oil and natural gas are well documented and severe. But in the president's push to reduce greenhouse gases and curtail global warming, his administration has allowed so-called green energy to do not-so-green things.
In some cases, such as its decision to allow wind farms to kill eagles, the administration accepts environmental costs because they pale in comparison to the havoc it believes global warming could ultimately cause.
Ethanol is different.
The government's predictions of the benefits have proven so inaccurate that independent scientists question whether it will ever achieve its central environmental goal: reducing greenhouse gases. That makes the hidden costs even more significant.
"This is an ecological disaster," said Craig Cox with the Environmental Working Group, a natural ally of the president that, like others, now finds itself at odds with the White House.