Common metal could efficiently produce fuel from sunlight

January 20th, 2011 - 1:58 pm ICT by ANI  

Washington, Jan 20 (ANI): A new study has found that a common metal found in self-cleaning ovens could efficiently convert sunlight into fuel.

Sossina Haile, at the California Institute of Technology, found that cerium oxide-or ceria could be used to concentrate solar energy and convert carbon dioxide and water into fuels.

The process developed by Haile and her colleagues would make it possible to store and transport solar energy over to different locations.

The researchers designed and built a two-foot-tall prototype reactor, which contains a cylindrical lining of ceria, that has a quartz window and a cavity that absorbs concentrated sunlight.

The concentrator works “like the magnifying glass you used as a kid” to focus the sun’s rays, says Haile.

Ceria can “exhale” oxygen from its crystalline framework at very high temperatures and then “inhale” oxygen back in at lower temperatures.

“What is special about the material is that it doesn’t release all of the oxygen. That helps to leave the framework of the material intact as oxygen leaves,” Haile said.

“When we cool it back down, the material’s thermodynamically preferred state is to pull oxygen back into the structure.”

Currently, the system harnesses less than 1 percent of the solar energy it receives, with most of the energy lost as heat through the reactor’s walls or by re-radiation through the quartz window.

“When we designed the reactor, we didn’t do much to control these losses,” says Haile.

Thermodynamic modelling by lead author and former Caltech graduate student William Chueh suggests that efficiencies of 15 percent or higher are possible.

Eventually, the process could be adopted in large-scale energy plants, allowing solar-derived power to be reliably available during the day and night, Haile said.

The CO2 emitted by vehicles could be collected and converted to fuel, “but that is difficult,” she says.

A more realistic scenario might be to take the CO2 emissions from coal-powered electric plants and convert them to transportation fuels.

“You’d effectively be using the carbon twice,” Haile explains.

Alternatively, she says, the reactor could be used in a “zero CO2 emissions” cycle: H2O and CO2 would be converted to methane, would fuel electricity-producing power plants that generate more CO2 and H2O, to keep the process going. (ANI)

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