Petitioning the EPA could also prove hard. In 2008, another drought year, Perry asked the agency to waive half of that year's mandate of 9 billion gallons of ethanol to be mixed into fuel.
The EPA turned the request down saying economic damage would have to be severe. In addition, the EPA signaled that future petitions would have to demonstrate that implementation of the mandate itself was causing the economic harm, not just contributing to it.
An EPA spokeswoman said on Friday the agency had not received any waiver petitions. If the EPA does get a request, it could take months for it to decide, as a public comment period and assembling a case for or against any petition takes time.
Even if the EPA granted a waiver, it is not certain that would have a big impact on corn prices. Bruce Babcock, an agricultural economist at Iowa State University of Iowa, said removing the mandate may only cut corn prices about 28 cents per bushel, or about 4.6 percent