Adding fuel-cell technology to power plants can nearly double a plant's efficiency and cut greenhouse-gas emissions, a U.S. materials-science professor says.

This technology can be a key to optimizing electricity production until natural resources such as sunlight, wind, rain, tides and geothermal power come of age, Northwestern University materials-science and engineering Professor Scott Barnett says.

"Fossil fuels like coal are going to be in use for a long time to come, until renewable-energy sources take over, and fuel cells provide a means for using them more efficiently and reducing our production of CO2," Barnett, of the McCormick School of Engineering and Applied Science, tells the school's McCormick Magazine.

To create electricity, power plants typically burn fossil fuels to create heat. The heat runs engines that drive turbines that generate electric power, the magazine says in an article titled "Energizing Research."

The multistep process has an efficiency rate of about 30 percent, the magazine says.

But fuel cells improve that efficiency by converting a fuel's chemical energy into electricity directly by exploiting the reaction between oxygen and hydrogen. The energy generated by combining fossil-fuel hydrogen with oxygen creates electricity at a 40 percent to 60 percent efficiency rate, nearly twice that of conventional power plants.

Fuel cells also have a much lower rate of carbon-dioxide emissions, the magazine says.

"The technology has come a long way," Barnett says.

It is currently used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. But several major automakers have committed in recent months to fuel-cell car production by 2015.

The cells are still expensive, but the technology is improving, making them increasingly market-worthy, Barnett says.

"People worry about cost, availability of materials, efficiency, and long-term durability," he tells the magazine. "We have predictions that look good but have to be fleshed out in practice."