Recent advances in compressed air storage in underground reservoirs

The concept of compressed air energy storage (CAES) is described; reservoir stability criteria are described; and the initial performance and results of a recent field test of CAES in Illinois are discussed. The CAES concept is a technically and economically promising means to store off-peak energy to meet peak electrical energy demand. Reservoir stability criteria have been developed for salt and hard rock reservoirs and interim criteria have been developed for porous rock reservoirs. A field test is underway at Pittsfield, Illinois to test porous sandstone reservoir behavior under CAES conditions. US Department of Energy authority and sponsorship for the test was transferred to the Electric Power Research Institute during air bubble development. Although injectivity was lower than anticipated, a sizeable quantity of air has been injected into the reservoir at the test site and plans call for cyclic testing under EPRI sponsorship.