The idea of compressed-air energy storage isn’t new, but cheap and plentiful energy has precluded much research. The low-tech explanation goes like this: excess energy from a power plant is used to run air compressors, which pump air into an underground cave, where it is stored under pressure. When released, the air powers a turbine, creating electricity. The initial energy used to force the air underground can come from wind, solar, nuclear or any source.

The technology could also help utilities meet their peak demand by collecting energy from wind farms, which generate most of their power at night, or by storing excess energy from nuclear plants, which are hard to power up and down.

A power generation plant with a compressed air energy storage system comprises a means to reduce the pressure of air extracted from a compressed air storage cavern for the use in a combustion turbine. The means to reduce the air pressure comprises at least one expansion turbine and means to control the size of pressure reduction. Furthermore, the expansion turbine is arranged on a rotor shaft that drives a generator. The means for pressure redact, according to the invention, avoid power losses and provide an increased overall efficiency of the power generation plant.

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http://gigaomcleantech/compressed-air-startup-to-inflate-utility-power-generation/