DEBBIE ELLIOTT, host:

With all the concern over global warming, nuclear power is getting a second look in this country. That's because nuclear reactors don't pump plumes of greenhouse gases into the atmosphere the way coal fire plants do. Some environmentalists are softening their opposition to nuclear. The Bush administration wants to see new reactors built. And some power companies are putting together plans to do that. But obstacles remain.

NPR's Chris Arnold reports on the prospects for nuclear power making a comeback.

CHRIS ARNOLD: The Bush administration doesn't beat a drum about global warming every often unless the subject is nuclear power.

Mr. SAMUEL BODMAN (Secretary of Energy): We must recognize the realities of global climate change.

ARNOLD: Energy Secretary Samuel Bodman spoke recently to the American Nuclear Society at his conference in Boston.

Mr. BODMAN: We need more nuclear power in this country, and this is the critical point. At present, nuclear power is the only mature technology that can supply large amounts of emissions-free base load power to help us meet the expected growth in demand.

ARNOLD: The U.S. currently has 104 nuclear reactors generating electricity, the most of any country in the world, but those are aging. After an accident at Three Mile Island and the Chernobyl disaster, this country lost its stomach for nuclear power. Utilities cancelled 96 new nuclear projects and a new reactor hasn't been built in the U.S. since.

Mr. BODMAN: And we have not licensed a new nuclear power plant in this country in over 30 years. That simply must change.

ARNOLD: Things are changing, according to some in the industry. Ted Quinn is a consultant and past president of the American Nuclear Society, made up of scientists, businesspeople, construction experts, power companies.

Mr. TED QUINN (Consultant, American Nuclear Society): We just finished a meeting this afternoon with our utilities and representatives from different states that they are moving ahead with 31 new nuclear units in the United States to go through licensing in the next three years.

ARNOLD: That is plans for 31 new nuclear power plants.

Mr. QUINN: So this is a new wave of both licensing and construction that will occur.

ARNOLD: Well, actually, it may not occur. Companies are jockeying for position right now to qualify for some federal subsidies if they do build a plant. So they've started the ball rolling on permits. But power companies may decide the new plants don't make sense. And it's not just because of controversy over where to put nuclear waste or safety concerns. Those are still issues. The biggest obstacle to nuclear right now is just basic economics: building a coal-burning plant is cheaper. In fact, because of that, despite the energy secretary's enthusiasm, the Department of Energy's own experts are skeptical that nuclear power will play a bigger role in years to come.

Mr. ALAN BEAMON (Director, Energy Information Administration): Absence in some change in policy, the economics favor coal in most regions of the country over nuclear.

ARNOLD: Alan Beamon is the director with the federal Energy Information Administration. The EIA predicts that nuclear power's share of electricity generation in the United States will fall in coming years. But there is something that could change that: tougher greenhouse gas regulations. The EIA recently did an analysis of some current proposals for a so-called cap-and-trade system to limit emissions.

Mr. BEAMON: In the most stringent case, the additions of nuclear capacity are so large that they essentially double current nuclear capacity that exists in the country.

ARNOLD: That's because greenhouse gas caps make burning coal more expensive so nuclear becomes more attractive. And there is enough global warming concern in Washington right now that such caps are considered likely.

Mr. KEN HUGHEY (Senior Manager, Nuclear Business Development, Entergy): I see environmental regulations on air qualities becoming stricter and stricter.

ARNOLD: That's Ken Hughey, a business development executive with Entergy, which runs 11 nuclear power plants and is currently seeking permits to build two new ones. Both would be located next to existing nuclear reactors. Hughey says like other companies, Entergy is trying to figure out how much a new plant would cost.

Mr. HUGHEY: The problem that we're having right now is getting those numbers refined enough that we can really price it out. And it is because we haven't built one in 30 years.

ARNOLD: Tougher emissions laws also would mean more power from renewables - solar, wind and biomass. But experts say those can't match a nuclear's output. So it might not be what some environmentalists were hoping for while pushing for tougher global warming laws but more nuclear power plants could be on the horizon.

Chris Arnold, NPR News, Boston. Transcript provided by NPR, Copyright NPR.