Out at the Wanapum Dam on the Columbia River, a new turbine is being tested that generates more electricity, but won't kill so many fish – thanks to research dollars from Uncle Sam.

Down in California's Long Valley, on the Sierra Nevada range, federal researchers are working to boost efficiency of geothermal energy, which uses the earth's natural heat to generate power.

But renewable energy advocates may have to kiss goodbye those and other research projects. The US Department of Energy (DOE) is quitting the hydropower and geothermal power research business – if Congress will let it.

Declaring them "mature technologies" that need no further funding, the Bush administration in its FY 2007 budget request eliminates hydropower and geothermal research, venerable programs with roots in the energy crises of the 1970s.

"What we do well is research and funding of new, novel technologies," says Craig Stevens, chief spokesman for the DOE. "From a policy perspective, geothermal and hydro are mature technologies. We believe the market can take the lead on this at this point."

Still, "zeroing out" such research could end up being a penny-wise, pound-foolish move, some energy advocates say. Any savings from the cuts would be nil since all of the nearly $24 million ($1 million from hydropower and $23 million from geothermal) research funding would go to other programs such as biofuels.

"I'm just astonished the department would zero out these very small existing budgets for geothermal and hydro – it makes no sense at all," says V. John White, executive director of the Center for Energy Efficiency and Renewable Technologies, an environmental group based in Sacramento, Calif. "These are very important resources for our energy future that could replace the need for a lot of coal-fired power plants."

Indeed, the costs of lost opportunities from dropping such research could be enormous in the long run, recent federal studies suggest.

Geothermal is a case in point. Its power plants need water, heat, and permeable rocks no deeper than about three miles beneath the surface to generate affordable electricity, says Karl Gawell, executive director of the Geothermal Energy Association, a Washington trade group.

Today more than 60 geothermal plants with the capacity of about three big coal-fired power plants produce less than 1 percent of the nation's electricity.

Yet geothermal holds vast potential – at least 30,000 megawatts of identified resources developable by 2050 and more unidentified resources, much of it in Western states, the National Renewable Energy Laboratory reported in May.

Research aims at new technologies that can use underground zones with good heat but little water and those with lower temperature rocks deeper in the earth.

"The idea that geothermal is a mature technology that doesn't need further research doesn't even pass the laugh test," says Mr. Gawell. "What they're saying is that if your program doesn't have to do with biofuels, wind, or solar, you won't have a program."

Meanwhile, the more than 5,400 potential "small hydro" power projects could produce about 20,000 megawatts of power, a DOE study in January found. And most would require no new dams at all, shunting a portion of a small river's flow to one side to make electricity. Others would add turbines to dams that don't have them yet.

Together, high-tech hydropower and geothermal resources could contribute at least enough power to replace more than 100 medium-size coal-fired power plants with emissions-free electricity – about the number now on the drawing board.

There have been moves in the Senate to restore DOE funding for geothermal, but far less support in the House, leaving uncertainty about the outcome, Gawell says. For hydropower, matters are worse. Though $4 million in funding has been proposed in the Senate, nothing has emerged from the House, observers say.

"There's this view that hydropower is a technology that's been around a long time, and there's not much more we can do to improve it – but we've got the next generation of hydropower – ocean, tidal, wave and conduit energy coming on," says Linda Church Ciocci, executive director of the National Hydropower Association, a Washington trade group.

Even those focused on environmental damage from dams worry about lost funding. "We'd like to see federal funding continue for new research on hydrokinetic systems and damless hydro," says Robbin Marks, director of the hydropower reform campaign at American Rivers, a Washington environmental group. "We're interested in understanding more about the environmental impact of those systems."

Power from tidal flows, waves, and irrigation canals are expanding the definition of hydropower – none of which are likely to get DOE research funding if the hydropower budget gets whacked, some observers say.

Others remain skeptical. "I find myself agreeing with the DOE argument that hydropower is a mature technology," says Jerry Taylor, the Cato Institute's director of Natural Resource Studies. "If there's economic merit to this area, then venture capitalists will put their money into it."

But that kind of waiting game would be a shame, says Trey Taylor, cofounder and president of Verdant Power in Arlington, Va. Two weeks ago his company received venture capital funding for its program. Next month, Verdant will deploy its first two underwater turbines in New York City's East River, the first step in an experimental technology that attempts to harness the tidal currents to create power.

But more firms would be competing to get into tidal power today – if the government shouldered more of the environmental research costs, Mr. Taylor says.

The current high cost of researching areas such as a technology's environmental impact makes it likely that a company will fail. He and his partners remortgaged their homes and begged friends for funds.

"I can understand the tight situation DOE is in," he says. "But what they're not seeing is that a whole new breed of technology has come on right now. The push for sustainable power is sweeping the globe."