By Dina Cappiello, CQ Staff

When it comes to making the U.S. energy independent, lawmakers seem to have oil — and only oil — on the brain.

Both the House and Senate versions of the energy bill, which is now the subject of intensifying negotiations, are aimed at reducing imports, either by boosting fuel economy or promoting alternative fuels. When Speaker Nancy Pelosi , a California Democrat, assembled the House Select Committee for Energy Independence and Global Warming this year, she charged it with “restoring our freedom from overreliance on foreign oil.”

But as congressional leaders seek to reduce costly oil imports, they may inadvertently spark increased dependence on foreign supplies of other fuels.

Take uranium, which the United States already imports at a higher rate than crude oil: 84 percent of the uranium used in nuclear power plants comes from abroad, as compared with 67 percent of the country’s crude oil, according to the Energy Information Administration. As energy companies ponder bringing as many as 31 new nuclear reactors on line in the coming years, the present overreliance on foreign uranium could bulk into a full-fledged addiction. “Uranium will continue to be imported because we don’t have many economic reserves in the United States,” says John Longenecker, a nuclear industry consultant who had previously served as assistant deputy director of the Energy Department’s nuclear division

Or take natural gas. Last month, Rice University’s Baker Institute for Public Policy released a study that showed a growing dependence on imported natural gas from places such as the Middle East and Africa. It concluded that by 2030 foreign sources of natural gas could account for one-third of consumer supply in the United States. That’s up from 19 percent today.

This pattern of dependence will probably accelerate under the initiatives — likely to be in any compromise energy bill — to control emissions of heat-trapping carbon dioxide, some experts say. Electric utilities, for example, will have strong incentives to switch from dirtier native coal to cheap international supplies of natural gas. Congress is already weighing renewable-fuel mandates for gasoline producers that are making them leery of expanding their refinery capacities.

Edward J. Markey , who chairs the House Energy Independence panel, says he intends to remain focused on the oil issue. “America’s dependence on foreign oil trumps all other energy imports in its sheer size and overall impact,” the Massachusetts Democrat said.

Not all observers agree that lawmakers can address oil dependence as a stand-alone priority. “From the point of view of protecting the economy, they should be more concerned about natural gas,” says Amy Myers Jaffe, an energy specialist at the Baker Institute. “As more countries use more natural gas, it will have the same geopolitics as oil.”