WASHINGTON - U.S. farmers could grow enough corn to produce 25 billion gallons of ethanol in 2030, twice as much as this year's target of 12 billion gallons, said the leader of a U.S. corn group on Thursday.

U.S. yields could double in 20 years, said Darrin Ihnen, president of the National Corn Growers Association.

Potentially, there would be enough corn in 2030 to produce 25 billion gallons of ethanol, he said.

A 2007 law set a ceiling of 15 billion gallons a year of corn-based ethanol to be blended into fuel in 2015 and a goal of 21 billion gallons of advanced biofuels, such as ethanol from cellulose found in woody plants, grass and crop debris.

If we don't get past the higher-blend issue, then even 15 billion (gallons) is moot, said Ihnen, referring to a proposal pending at the Environmental Protection Agency to allow up to 15 percent ethanol in gasoline.

The blend rate for years has been 10 percent. Ethanol backers say at that level, they will saturate the gasoline market before reaching the 15 billion-gallon level.

(Reporting by Charles Abbott; Editing by Lisa Shumaker)