Patent ID: 8850808

Claim:
A compressed air energy storage system comprising a low pressure subsystem, the low pressure subsystem comprising: a low pressure hydraulic vessel adapted to contain a heat transfer liquid and comprising a low pressure piston disposed therein for horizontal reciprocating movement; first and second low pressure vessels coupled to the low pressure hydraulic vessel on opposite sides of the low pressure piston, each adapted to contain at least one of the heat transfer liquid and a gas, each of the first and second low pressure vessels including a valve adapted to introduce ambient pressure gas into the respective low pressure vessel; and first and second heat transfer devices respectively coupled to and disposed within the first and second low pressure vessels, wherein: the low pressure piston is moveable in a first direction to displace at least some of the heat transfer liquid from the low pressure hydraulic vessel to the first low pressure vessel to compress ambient pressure gas in the first low pressure vessel, and the low pressure piston is moveable in a second direction to displace at least some of the heat transfer liquid from the low pressure hydraulic vessel to the second low pressure vessel to compress ambient pressure gas in the second low pressure vessel.