How green is nuclear power?

In Kansas, where winds blow strong, the push for clean energy includes not only new wind turbines but also new nuclear-power plants as part of a "carbon-free" solution to climate change.

It's an idea that may be catching on. At least 11 new nuclear plants are in the design stage in nine states, including Virginia, Texas, and Florida, according to the Nuclear Energy Institute website.

But that carbon-free pitch has researchers asking anew: How carbon-free is nuclear power? And how cost-effective is it in the fight to slow global warming?

"Saying nuclear is carbon-free is not true," says Uwe Fritsche, a researcher at the Öko Institut in Darmstadt, Germany, who has conducted a life-cycle analysis of the plants. "It's less carbon-intensive than fossil fuel. But if you are honest, scientifically speaking, the truth is: There is no carbon-free energy. There's no free lunch."

Nuclear power has more than just a little greenhouse gas attached to it, when mining uranium ore, refining and enriching fuel, building the plant, and operating it are included. A big 1,250 megawatt plant produces the equivalent of 250,000 tons of carbon dioxide a year during its life, Dr. Fritsche says.

That's still much less than coal-fired power plants and natural-gas turbines. It even does better than solar power and small-scale hydro projects. However, the gap with solar is closing and emissions from manufacturing photovoltaic panels are now on par with nuclear, a new study funded by the US Energy Department finds.

Officials in the nuclear power industry say references to carbon-free energy in their promotions refer only to the power-plant operation – and are not intended to describe carbon emissions during the entire nuclear life cycle.

"Yes, absolutely there's carbon," says Paul Genoa, director of policy development for the Nuclear Energy Institute, which represents the nuclear power industry in the US. "Most studies have found life-cycle emissions of nuclear to be comparable with renewable. Some show nuclear to be extremely high, but we do not find those credible."

Neither do many researchers. A 2003 Massachusetts Institute of Technology study recommended vast expansion of nuclear power to make a dent in the climate-change problem. Princeton researchers also cited it as an option, although they acknowledged concerns about terror threats and potential accidents.

One University of Wisconsin life-cycle emissions study in 2003 found even lower carbon emissions for nuclear than for most renewables. "We found wind and nuclear fission to have the lowest greenhouse-gas emissions over their life-cycle," says Paul Meier, director of the energy institute at the university. "We didn't include biomass and some of the others now available."

Yet it's not so much nuclear's carbon emissions, which are still relatively modest, but its cost-effectiveness in reducing carbon-dioxide emissions globally that's the key question, researchers say. Few studies have addressed that question.

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