California Might Use Compressed Air to Generate Electricity

Wind farms produce more than enough electricity at night -- when demand is lowest. One option for storing the excess energy is to capture the resource that generates it. In effect, to bottle the wind.

Or cram it into caves.

Which is what Pacific Gas & Electricity would like to do. The utility just received a $25 million award from money set aside in stimulus funds for smart-grid projects. The award will help pay for a study to find out if California can pack away pressurized air in underground caverns.

Here's how a compressed-air power plant would work. At night, wind turbines would force air into porous rock in Kern County, Calif. In the morning, the compressed air would be released to rotate turbines, which would generate up to 300 MW of electricity.

The generating plant will cost about $365 million. According to CleanTechnica, building a fossil-fuel plant that supplies the same amount of energy would come to $850 million.