Compressed air energy storage

Compressed Air Energy Storage (CAES) refers to the compression of air during periods of low energy demand, for use in meeting periods of higher demand. Typically, compression is done with an electrically powered turbo-compressor; and expansion is done with a natural-gas powered 'expander' (heater) which drives a combustion turbine. Installations exist in Huntorf, Germany, and McIntosh, Alabama (USA). An additional facility is under development in Norton, Ohio. Air is stored underground in a cavern created by solution mining (salt is dissolved away) or an abandoned mine. Plants are designed to operate on a daily cycle, charging at night and discharging during the day.