Patent ID: 6994156

Claim:
A thermal storage device for storing cooled liquid comprising: a. a cavity in the earth's surface with contents that comprise a pool of aqueous liquid; b. a liner that is substantially impermeable to liquid and which covers the bottom of said cavity so as to contain said pool of aqueous liquid; c. sidewalls of said cavity that comprise an earthen material with any structural reinforcement to said sidewalls capable of being supplied essentially by said contents of said liner; d. a protective layer over the top of said pool of aqueous liquid that prevents transmission of solar radiation into said pool of aqueous liquid and reduces heat transfer between said pool and the environment; and e. a fluid circuit that comprises i. a cooler that cools liquid, ii. a cooling load that comprises a heat exchanger between said liquid and a second fluid to be cooled, and iii. means for moving liquid that moves liquid reversibly in a vertical direction through said pool such that when storage of cooling capacity is required, said means for moving liquid withdraws warm liquid near the top of said pool, moves the liquid through said cooler, which cools the liquid to form cooled liquid, and supplies the cooled liquid near the bottom of said pool which causes cooled liquid to displace warm liquid upward through the pool and when retrieval of stored coo ing capacity is required, the means for moving liquid withdraws cooled liquid near the bcttom of said pool, moves it through said cooling load, which warms the liquid, and supplies warm liquid near the top of said pool, which causes warm liquid to displace cooled liquid downward through the pool and thereby provided storage and retrieval of useful cooling to the cooling load.