A renewable fuels requirement will be one of the more contentious issues that members of a special Senate-House of Representatives conference committee will have to address as they try to hammer out legislation to update U.S. energy policy for the first time in a decade.

A Senate-passed energy bill included a requirement to triple the amount of renewable fuels, like ethanol and biodiesel, used to 5 billion gallons a year by 2012. The House of Representatives's energy legislation does not have a similar mandate.

U.S. Energy Secretary Spencer Abraham asked lawmakers on the conference committee last week to include the Senate's renewable fuels language in a final energy bill.

"The administration supports the renewable fuels standard compromise contained in the Senate bill and urges conferees to adopt it," Abraham said in a letter last week to conferees.

"This provision will increase the use of clean, domestically produced renewable fuels, like ethanol, which will improve the nation's energy security, farm economy, and environment," Abraham said.

While Bush has endorsed more ethanol use, a recent internal administration document said a jump in ethanol consumption would increase gasoline costs and might create fuel supply shortages in some areas.

The renewable fuels agreement in the Senate bill would also ban MTBE, a gasoline additive that many states already are phasing out because MTBE has leaked from underground storage tanks and polluted drinking water.

The Senate's renewable fuels mandate was the result of a compromise reached between the American Petroleum Institute and the Renewable Fuels Association (RFA), which is the trade group that represents ethanol producers.

The agreement also has the support of Northeast states, U.S. Chamber of Commerce, American Farm Bureau and the American Lung Association.

RFA President Bob Dinneen said the administration's letter to conferees "puts in black and white what President Bush has been saying all along that this country needs to use more domestic, renewable fuels like ethanol and biodiesel."

"We feel confident that the historic coalition of support for this fuels agreement will ensure its inclusion in the final energy bill," Dinneen said.

The Oxygenated Fuels Association, which represents MTBE producers, has questioned the environmental benefits of ethanol, arguing that the fuel additive may result in more pollution and could raise gasoline prices.

The trade group also said that instead of banning MTBE, federal and state agencies should enforce laws that punish energy companies with leaky storage tanks.