The tax credit debate directly affects Northeast Iowa. Ethanol plants are located in Fairbank, Shell Rock, Iowa Falls, Steamboat Rock, Charles City, Lawler and St. Ansgar. A biodiesel facility is also located in Iowa Falls. The plants buy hundreds of thousands of bushels of corn and soybeans from area farmers and hundreds of people rely on them for jobs.

Credits were approved years ago to promote renewable fuels and get them established in the marketplace. In biodiesel's case, the financial incentive offset high production costs and provided a chance for profitability.

Opponents of biofuel tax credits say the country can't afford to give away billions of dollars to refiners that don't need it, or the money needs to be invested to promote other forms of renewable energy.

Bruce Babcock, an economics professor and director of the Center for Agricultural and Rural Development at Iowa State University, said the credits aren't needed. In a study released by ISU in July, it asserts the nation's renewable fuels standard requires ethanol and biodiesel to be blended with petroleum already, so credits are overkill.

"The beneficiaries of the tax credit(s) is the blenders," Babcock said. "They are already obligated to meet mandates, so we're letting them off the hook by paying them extra. It doesn't make much sense to me."