High efficiency, closed, scalable, liquid and compressed air storage and generation system.

Abstract

A closed cycle power storage and generation system comprising compressed air storage J and liquefied air energy storage D, wherein air is compressed in a compressor A, before being cooled in a heat ex

Description

The invention comprises a closed loop energy storage system which combines elements of both compressed air and liquid air energy storage systems. The system is split into an energy storage system and an energy recovery system, which are joined through both compressed air storage and liquid air storage (D), vessels. When storing power, electrical power is used to compress air in A, to form a high pressure (HP) air stream. The HP air is passed through a heat exchanger B, which is used to substantially cool the HP air stream to cryogenic temperatures. The HP air is then expanded in an expansion valve C, to form a low pressure (LP) mix of gaseous and liquid air. The liquidised mass fraction mi, is extracted and stored in D. The residual, LP, un-liquidised, air stream is then mixed at valve E, with LP cryogenic air of mass flow mi, to entirely replace the liquidised mass fraction. This LP cryogenic gaseous air is produced either directly by the power generation cycle, or it is drawn from compressed air stored in J, which is then expanded through the appropriate stage of expander H, to produce LP cryogenic air (this expansion process will generate power, offsetting the electrical power used to compress it for storage). The regenerated LP cryogenic air flow now enters the cold side of the heat exchanger B, to provide the maximum possible cooling of the HP air stream entering the hot side of the heat exchanger. The LP air stream now re-enters the compressor and the cycle re-starts. During the power generation process, LP liquid air is drawn from D, and pressurised to a very high pressure in a cryopump F. This high pressure, liquid air is passed through a multi-heat-source, heat exchanger G. In G, the liquid air is heated to a temperature where its enthalpy (Sent), corresponds to its saturated vapour enthalpy (Ssatvap) upon expansion to LP (ie Scrit= Ssatvap @ LP). This recovers the maximum amount of power upon expansion and provides cryogenic gaseous air to be used for cooling in the power storage cycle. The superheated air is passed to a multi-stage expander H, for power generation by expansion to LP. The system is closed because the LP expanded cryogenic air is recovered and either directly used in the power storage process (added at valve E), or compressed until its enthalpy at ambient temperature corresponds to the saturated vapour enthalpy at LP (ie Sent @ Tambient=SsatVap @LP). The volume of the working fluid (and the system’s overall energy storage capacity) can be increased by drawing dry, CO2 scrubbed air into compressor I, compressing it for storage and allowing it to cool to ambient temperature. Adjusting the system flow rate can be used to scale power storage and power generation rates. KEY A. Air compressor B. Heat exchanger C. Expansion valve D. Cryogenic liquid storage vessel(s) E. Mixing valve F. Cryogenic liquid pump G. Multi source heat exchanger H. Gas expander I. Cryogenic gas compressor J. Ambient compressed gas storage vessel(s)

Claims

creation of a closed cycle power storage and generation system combining compressed gas energy storage with liquid gas energy storage, comprising a compressor (A), a recuperating heat exchanger (B), an expansion valve (C), a liquified gas vessel (D), a cryogenic pump (F), a second heat exchange process (G), a multi-pressure expansion process (H), compressed gas storage vessel(s)(J), a second compressor (I), and a valve (E), for regenerating the initial mass flow rate.

2. The creation of power generation cycle according to claim (1), where the expansion process (H) always yield gas at its saturated vapour temperature through the co-ordination of the expander (H) inlet temperatures and pressures.

3. The creation of a gas liquefaction system according to claim (1), in which the expanded cryogenic gas is retained and utilised for cooling, via the recuperation heat exchanger (B).

4. The creation of a gas liquefaction cycle according to claim (1), where the “regeneration valve” (E), is placed between the liquid storage (D), and the cold inlet of the recuperation heat exchanger (B), (rather than between the cold outlet of the recuperation heat exchanger (B), and the inlet of compressor (A)).

5. The creation of a compressed gas cold storage system according to claim (1), for the storage of cryogenic temperatures at ambient temperature without the need for heat exchangers or heavily insulated “cold storage” media.

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