Pumped Thermal Storage Cycles with Recuperation

• US 20170321967A1
• Filed: 02/23/2017
• Published: 11/09/2017
• Est. Priority Date: 09/27/2012
• Status: Active Grant

• Current Assignee: Malta, Inc.
• Original Assignee: X Development LLC (Alphabet Inc.)
• Inventors: Laughlin, Robert B., Larochelle, Philippe, Cizek, Nicholas
• Granted Patent: US 10,458,721 B2
• Time in Patent Office: Days
• CPC Class Codes: F01K 13/02 Controlling, e.g. stopping or starting
• CPC Class Codes: F01K 3/00 Plants characterised by the use of steam or heat accumulators, or intermediate steam heaters, therein regenerating exhaust steam F01K19/00
• CPC Class Codes: F01K 3/12 having two or more accumulators
• CPC Class Codes: F01K 3/185 using waste heat from outside the plant F02G5/00 takes precedence
• CPC Class Codes: F01K 3/20 with heating by combustion gases of main boiler
• CPC Class Codes: F02C 1/10 Closed cycles
• CPC Class Codes: F02C 6/14 Gas-turbine plants having means for storing energy, e.g. for meeting peak loads
• CPC Class Codes: F05D 2250/90 Variable geometry
• CPC Class Codes: F24S 60/10 using latent heat
• CPC Class Codes: F28D 15/00 Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies F28D17/00, F28D19/00, F28D20/00 take precedence
• CPC Class Codes: F28D 20/00 Heat storage plants or apparatus in general; Regenerative heat-exchange apparatus not covered by groups F28D17/00 or F28D19/00
• CPC Class Codes: F28D 2020/0047 using molten salts or liquid metals
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 20/14 Combined heat and power generation [CHP]
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 60/14 Thermal energy storage
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids

Abstract

The present disclosure provides pumped thermal energy storage systems that can be used to store electrical energy. A pumped thermal energy storage system of the present disclosure can store energy by operating as a heat pump or refrigerator, whereby net work input can be used to transfer heat from the cold side to the hot side. A working fluid of the system is capable of efficient heat exchange with heat storage fluids on a hot side of the system and on a cold side of the system. The system can extract energy by operating as a heat engine transferring heat from the hot side to the cold side, which can result in net work output. Systems of the present disclosure can employ solar heating for improved storage efficiency.

Claims

1. A system configured to operate in a heat pump mode, the system comprising:

a compressor;

a hot side heat exchanger;

a hot thermal storage (“

HTS”

) medium;

a turbine;

a cold side heat exchanger;

a cold thermal storage (“

CTS”

) medium;

a recuperative heat exchanger;

a working fluid; and

a closed cycle fluid path configured to circulate the working fluid through, in sequence, the compressor, the hot side heat exchanger, the recuperative heat exchanger via a high pressure side of the recuperative heat exchanger, the turbine, the cold side heat exchanger, the recuperative heat exchanger via a low pressure side of the recuperative heat exchanger, and back to the compressor, wherein the working fluid exchanges heat with the HTS medium in the hot side heat exchanger, wherein the working fluid exchanges heat with the CTS medium in the cold side heat exchanger, and wherein the working fluid in the high pressure side of the recuperative heat exchanger exchanges heat with the working fluid in the low pressure side of the recuperative heat exchanger.

2. The system of claim 1, wherein the system is configured to reject heat from the working fluid to an external environment along the closed cycle fluid path between exiting the high pressure side of the recuperative heat exchanger and entering the turbine.

3. The system of claim 2, wherein the system is configured to reject heat from the working fluid to the external environment via a radiator.

4. The system of claim 1, wherein the HTS medium is molten salt.

5. The system of claim 1, wherein the CTS medium is hexane.

6. A system configured to operate in a heat engine mode, the system comprising:

a compressor;

a hot side heat exchanger;

a hot thermal storage (“

HTS”

) medium;

a turbine;

a cold side heat exchanger;

a cold thermal storage (“

CTS”

) medium;

a recuperative heat exchanger;

a working fluid; and

a closed cycle fluid path configured to circulate the working fluid through, in sequence, the compressor, the recuperative heat exchanger via a high pressure side of the recuperative heat exchanger, the hot side heat exchanger, the turbine, the recuperative heat exchanger via a low pressure side of the recuperative heat exchanger, the cold side heat exchanger, and back to the compressor, wherein the working fluid exchanges heat with the HTS medium in the hot side heat exchanger, wherein the working fluid exchanges heat with the CTS medium in the cold side heat exchanger, and wherein the working fluid in the high pressure side of the recuperative heat exchanger exchanges heat with the working fluid in the low pressure side of the recuperative heat exchanger.

7. The system of claim 6, wherein the system is configured to reject heat from the working fluid to an external environment along the closed cycle fluid path between exiting entering the turbine and entering the low pressure side of the recuperative heat exchanger.

8. The system of claim 7, wherein the system is configured to reject heat from the working fluid to the external environment via a radiator.

9. The system of claim 6, wherein the HTS medium is molten salt.

10. The system of claim 6, wherein the CTS medium is hexane.

11. The system of claim 6 further comprising a heat rejection device in thermal contact with the CTS medium and configured to reject heat from the CTS medium to an external environment.

12. The system of claim 11, wherein the heat rejection device is a radiator.

13. The system of claim 11, wherein the heat rejection device is in thermal contact with a heat sink.

14. The system of claim 6 further comprising a heat rejection device in thermal contact with the HTS medium and configured to reject heat from the HTS medium to an external environment.

15. The system of claim 14, wherein the heat rejection device is a radiator.

16. The system of claim 14, wherein the heat rejection device is in thermal contact with a heat sink.

17. The system of claim 6 further comprising:

a first CTS tank;

a second CTS tank;

an intermediate CTS tank;

a first CTS fluid path configured to flow CTS medium from the first CTS tank through the cold side heat exchanger and to the intermediate CTS tank;

a second CTS fluid path configured to flow CTS medium from the intermediate CTS tank to the second CTS tank.

18. The system of claim 6 further comprising:

a first HTS tank;

a second HTS tank;

an intermediate HTS tank;

a first HTS fluid path configured to flow HTS medium from the first HTS tank through the hot side heat exchanger and to the intermediate HTS tank;

a second CTS fluid path configured to flow HTS medium from the intermediate HTS tank to the second HTS tank.

19. A system configured to operate in a heat pump mode, the system comprising:

a compressor;

a hot side heat exchanger;

a turbine;

a cold side heat exchanger;

a cold thermal storage (“

CTS”

) medium;

a hot side recuperative heat exchanger;

a cold side recuperative heat exchanger;

a thermal fluid;

a working fluid;

a closed cycle fluid path configured to circulate the working fluid through, in sequence, the compressor, the hot side heat exchanger, the hot side recuperative heat exchanger, the turbine, the cold side heat exchanger, the cold side recuperative heat exchanger, and back to the compressor, wherein the working fluid exchanges heat with the HTS medium in the hot side heat exchanger, wherein the working fluid exchanges heat with the CTS medium in the cold side heat exchanger; and

a thermal fluid path configured to circulate the thermal fluid between the hot side recuperative heat exchanger and the cold side recuperative heat exchanger, wherein the working fluid in the hot side recuperative heat exchanger exchanges heat with the thermal fluid, and wherein the working fluid in the cold side recuperative heat exchanger exchanges heat with the thermal fluid.

20. A system configured to operate in at least a heat pump mode and a heat engine mode, the system comprising:

a compressor;

a hot side heat exchanger;

a turbine;

a cold side heat exchanger;

a recuperative heat exchanger;

a working fluid;

a first closed cycle fluid path for operation of the system in the heat pump mode and configured to circulate the working fluid through, in sequence, the compressor, the hot side heat exchanger, the recuperative heat exchanger via a high pressure side of the recuperative heat exchanger, the turbine, the cold side heat exchanger, the recuperative heat exchanger via a low pressure side of the recuperative heat exchanger, and back to the compressor, wherein the working fluid in the high pressure side of the recuperative heat exchanger exchanges heat with the working fluid in the low pressure side of the recuperative heat exchanger;

a second closed cycle fluid path for operation of the system in the heat engine mode and configured to circulate the working fluid through, in sequence, the compressor, the recuperative heat exchanger via a high pressure side of the recuperative heat exchanger, the hot side heat exchanger, the turbine, the recuperative heat exchanger via a low pressure side of the recuperative heat exchanger, the cold side heat exchanger, and back to the compressor, wherein the working fluid in the high pressure side of the recuperative heat exchanger exchanges heat with the working fluid in the low pressure side of the recuperative heat exchanger; and

a plurality of valves configured to switch circulation of the working fluid between the first closed cycle fluid path for operation of the system in the heat pump mode and the second closed cycle fluid path for operation of the system in the heat engine mode.