The Environmental Protection Agency proposed lowering requirements for biofuel use in 2014 on November 15, cutting corn-based ethanol targets for the first time since the Renewable Fuel Standard (RFS) was established in 2007.

The reduction brings the 2014 requirements for renewables down to 2012 levels, with a 15.21-billion-gallon ceiling, according to the EPA's announcement last month. The proposed level falls about 16 percent below the 18.15-billion-gallon target Congress had originally called for, and about nine percent below the 16.55-billion-gallon requirement for this year. The new EPA standard, which includes target ranges for each kind of renewable fuel, will be subject to comment before the agency settles on quotas in the first quarter of 2014.

"Advances in vehicle fuel economy and other economic factors have pushed gasoline consumption far lower than what was expected when Congress passed the Renewable Fuel Standard in 2007," the EPA said in a statement. "As a result, we are now at the "E10 blend wall,'" which is the maximum level of ethanol that can be added to gasoline without switching to a higher-percentage blend like E15 or E85. E15 has been criticized by a variety of trade organizations for the potential harm it can cause in the small engines found on boats, outdoor power equipment and the like.

The biggest renewable fuel is corn-based ethanol, which will amount to about 13.8 billion gallons this year and would be limited to 13 billion gallons next year under the proposal. In 2007, Congress set a 15-billion-gallon limit on corn-based ethanol because of concern about using food for fuel. Ethanol is expected to consume about 38 percent of this year's record corn crop.

EPA teased a possible reduction in the 2014 RFS as far back as August. "[T]here are constraints in the market's ability to consume renewable fuels at the volumes specified in the Clean Air Act in future years "?(R)? EPA anticipates proposing adjustments to the 2014 volume requirements in the 2014 rule to address these constraints," the agency said in a statement on the 2013 fuel standards.