US looks ahead after ethanol subsidy expires

Doug Koplow of the policy consulting firm Earth Track said that the mandate is effectively another kind of subsidy for ethanol, and warns that it may be difficult to come up with new alternative fuels without adverse environmental impacts.

While there has been some enthusiasm about biofuels from switchgrass, cornstalks and algae, Koplow said, "I think people are painting that as too rosy a picture."

Even these alternatives "will require an enormous amount of land, and crops produced on a large scale. They will require chemical or water inputs," Koplow said, adding that he sees no "single solution" on fuels.