Compressed gas energy storage system
View Patent ↗Embodiments of the present invention use compressed air to store and deliver electrical, mechanical, and/or thermal power with high round-trip efficiency. Various embodiments may be scalable for use in a variety of environments—from wind farms to power plants to motor vehicles. An energy storage system according to the present invention can operate as a stand-alone storage system that connects electrically to the grid, it can be tightly integrated with a wind turbine, and/or it can be co-located with a thermal power generation facility and operate with even higher efficiency by scavenging low-grade waste heat.
1. An energy storage and recovery system comprising:
a reversible compressor/expander in selective fluid communication with a compressed gas storage unit and comprising an element configured to introduce liquid to effect gas-liquid heat exchange with gas being compressed or expanded within the reversible compressor/expander;
a gas-liquid separator configured to separate the liquid from a gas-liquid mixture received from the reversible compressor/expander;
an insulated thermal storage unit in thermal communication with separated liquid; and
a second insulated thermal storage unit configured to be in thermal communication with liquid separated by a second gas-liquid separator when the reversible compressor/expander is operating as a compressor.
2. An energy storage and recovery system as in claim 1 wherein the insulated thermal storage unit is configured to store the separated liquid.
3. An energy storage and recovery system as in claim 1 wherein the insulated thermal storage unit is configured to store a second liquid in thermal communication with the separated liquid through a heat exchanger.
4. An energy storage and recovery system as in claim 3 wherein the second liquid is maintained at a lower pressure than the gas-liquid mixture.
5. An energy storage and recovery system as in claim 3 wherein the separated liquid and the second liquid comprise water.
6. An energy storage and recovery system as in claim 3 wherein the separated liquid comprises water and the second liquid comprises an oil.
7. An energy storage and recovery system as in claim 3 wherein the heat exchanger comprises a tube-in-shell heat exchanger.
8. An energy storage and recovery system as in claim 3 wherein the heat exchanger comprises a counter flow heat exchanger.
9. An energy storage and recovery system as in claim 1 wherein the heat source is internal to the energy storage and recovery system.
10. An energy storage and recovery system as in claim 1 wherein the heat source is external to the energy storage and recovery system.
11. An energy storage and recovery system as in claim 1 further comprising a second insulated thermal storage unit configured to be in thermal communication with the separated liquid when the reversible compressor/expander is operating as a compressor.
12. An energy storage and recovery system as in claim 11 wherein the second insulated thermal storage unit is in thermal communication with a heat source.
13. An energy storage and recovery system as in claim 1 wherein the insulated thermal storage unit is configured to store a second liquid in thermal communication with the separated liquid through a heat exchanger.
14. An energy storage and recovery system as in claim 1 wherein the second insulated thermal storage unit is in thermal communication with a heat sink.
15. An energy storage and recovery system as in claim 1 wherein the reversible compressor/expander undergoes rotational motion.
16. An energy storage and recovery system as in claim 15 wherein the reversible compressor/expander comprises a turbine.
17. An energy storage and recovery system as in claim 1 wherein the reversible compressor/expander undergoes reciprocating motion.
18. An energy storage and recovery system as in claim 17 wherein the reversible compressor/expander comprises a crankshaft.
19. An energy storage and recovery system as in claim 1 wherein the element is configured to introduce liquid directly into the reversible compressor/expander.
20. An energy storage and recovery system as in claim 1 wherein the element is configured to introduce liquid upstream of the reversible compressor/expander.
21. An energy storage and recovery system as in claim 1 wherein the reversible compressor/expander further comprises an actively controlled valve.
22. An energy storage and recovery system as in claim 1 wherein:
the reversible compressor/expander comprises a valve pocket; and
the element comprises a sprayer in the valve pocket.