Varying Compression Ratios in Energy Storage and Retrieval Systems

• US 20170159496A1
• Filed: 02/23/2017
• Published: 06/08/2017
• Est. Priority Date: 09/27/2012
• Status: Active Grant

• Current Assignee: X Development LLC (Alphabet Inc.)
• Original Assignee: X Development LLC (Alphabet Inc.)
• Inventors: Larochelle, Philippe, Laughlin, Robert B., Cizek, Nicholas
• Granted Patent: US 10,458,283 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 method comprising:

operating a pumped thermal system in a charging cycle at a first compression ratio, wherein the pumped thermal system comprises a working fluid circulating through, in sequence, a compressor system, a hot side heat exchanger, a turbine system, and a cold side heat exchanger, wherein the working fluid is in thermal contact with a hot thermal storage (“

HTS”

) medium in the hot side heat exchanger and the working fluid is in thermal contact with a cold thermal storage (“

CTS”

) medium in the cold side heat exchanger; and

operating the pumped thermal system in a discharging cycle at a second compression ratio different than the first compression ratio.

2. The method of claim 1, wherein the compressor system comprises at least a first compressor and the second compressor.

3. The method of claim 2, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first compressor and the second compressor in parallel, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the first compressor and the second compressor in series.

4. The method of claim 2, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first compressor and not the second compressor, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the second compressor and not the first compressor.

5. The method of claim 2, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first compressor and not the second compressor, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the first compressor and the second compressor.

6. The method of claim 1, wherein the turbine system comprises at least a first turbine and a second turbine.

7. The method of claim 6, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first turbine and the second turbine in series, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the first turbine and the second turbine in series.

8. The method of claim 6, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first turbine and not the second turbine, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the second turbine and not the first turbine.

9. The method of claim 6, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first turbine and the second turbine, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the first turbine and not the first turbine.

10. The method of claim 1, wherein the compressor system comprises a compressor, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises operating the compressor at a first rotation speed, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises operating the compressor at a second rotation speed different than the first rotation speed.

11. The method of claim 1, wherein the turbine system comprises a turbine, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises operating the turbine at a first rotation speed, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises operating the turbine at a second rotation speed different than the first rotation speed.

12. The method of claim 1, wherein the compressor system comprises at least a first compressor and a second compressor, wherein the turbine system comprises at least a first turbine and a second turbine, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises circulating the working fluid through the first compressor and the first turbine and not circulating the working fluid through the second compressor and the second turbine, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises circulating the working fluid through the second compressor and the second turbine and not circulating the working fluid through the first compressor and the first turbine.

13. The method of claim 1, wherein the compressor system comprises a compressor comprising a variable pressure stator, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises tuning the variable stator to operate the compressor at a third compression ratio across the compressor, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises tuning the variable stator to operate the compressor at a fourth compression ratio across the compressor.

14. The method of claim 1, wherein the turbine system comprises a turbine comprising a variable pressure stator, wherein operating the pumped thermal system in the charging cycle at the first compression ratio comprises tuning the variable stator to operate the turbine at a third compression ratio across the turbine, and wherein operating the pumped thermal system in the discharging cycle at the second compression ratio comprises tuning the variable stator to operate the turbine at a fourth compression ratio across the turbine.

15. The method of claim 1, wherein the first compression ratio is a value such that

16. The method of claim 1, wherein the second compression ratio is a value such that

17. The method of claim 1, wherein the second compression ratio is greater than the first compression ratio.

18. The method of claim 17, wherein the first compression ratio is less than 3 and the second compression ratio is greater than 3. [0129]

19. The method of claim 1, wherein the first compression ratio varies based at least in part on a temperature of the working fluid.

20. The method of claim 1, wherein the second compression ratio varies based at least in part on a temperature of the working fluid.