Energy storage systems with medium voltage electrical heat exchangers

• US 9,523,285 B2
• Filed: 12/13/2013
• Issued: 12/20/2016
• Est. Priority Date: 12/13/2013
• Status: Active Grant

• Current Assignee: Chromalox Incorporated (Spirax-Sarco Engineering PLC)
• Original Assignee: Chromalox Incorporated (Spirax-Sarco Engineering PLC)
• Inventors: Heiligenstein, Adam, Wheeler, Mark, Molnar, Christopher
• Primary Examiner(s): Denion, Thomas
• Assistant Examiner(s): MIAN, SHAFIQ A
• Application Number:
  US14/105,951
• Publication Number:
  US 20150167489A1
• Time in Patent Office: 1,103 Days
• US Class Current: 1/1
• CPC Class Codes: F01D 15/10 Adaptations for driving, or combinations with, electric generators
• CPC Class Codes: F01K 3/186 using electric heat
• CPC Class Codes: F01K 5/02 used in regenerative installation
• CPC Class Codes: F02C 6/16 for storing compressed air
• CPC Class Codes: F05D 2260/42 Storage of energy
• 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: H02J 15/00 Systems for storing electric energy mechanical systems therefor F01-F04; in chemical form H01M
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/28 Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H05B 3/50 heating conductor arranged in metal tubes, the radiating surface having heat-conducting fins
• CPC Class Codes: Y02E 60/14 Thermal energy storage
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

Energy storage systems and methods use medium voltage (MV) electrical heat exchangers to increase the efficiency of the energy storage system and/or reduce emission of pollutants. MV electrical heat exchangers use medium range voltages to heat a fluid, such as a gas or liquid. The heated fluid is used in the energy storage system to either drive a turbine generator directly or indirectly, such as by generating steam to drive the turbine generator. The electricity used to power the MV electrical heat exchangers can be from renewable energy sources, such as solar or wind-powered sources, further increasing efficiency of the energy storage system.

Claims

1. An energy storage system comprising:

a reservoir storing a fluid for heating;

a medium voltage electrical heat exchanger connected to the reservoir for heating the fluid, wherein the medium voltage electrical heat exchanger comprises one or more medium voltage resistive heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive;

a turbine driven by the heated fluid; and

an electrical generator connected to the turbine for generating electricity,

wherein the one or more medium voltage resistive heating elements each comprise;

an outer metal sheath;

a resistive wire; and

a dielectric core positioned within the outer metal sheath, wherein the dielectric core comprises;

a first series of two or more axially-aligned, outer tubular dielectric bodies positioned end-to-end; and

a second series of two or more axially-aligned, inner tubular dielectric bodies,

wherein;

the inner tubular dielectric bodies are positioned end-to-end in the sheath and are nested inside the outer tubular dielectric bodies;

the inner tubular dielectric bodies define an interior passageway and the resistive wire is positioned in the interior passageway; and

the inner tubular dielectric bodies are longitudinally staggered relative to the outer tubular dielectric bodies.

2. The energy storage system of claim 1, further comprising a renewable energy source that supplies the voltage between 601 V and 69,000 V, inclusive, to the medium voltage resistive heating elements of the medium voltage electrical heat exchanger to heat the fluid.

3. The energy storage system of claim 1, wherein:

the reservoir comprises compressed gas as the fluid; and

the compressed gas from the reservoir flows to the medium voltage electrical heat exchanger,

whereupon the medium voltage electrical heat exchanger heats the gas upon decompression of the gas; and

the turbine is powered by flow of the decompressed gas.

4. The energy storage system of claim 1, wherein:

the reservoir comprises a first tank; and

the fluid in the first tank comprises molten salt.

5. The energy storage system of claim 2, wherein the renewable energy source comprises a wind-powered renewable energy source.

6. The energy storage system of claim 3, further comprising:

a compressor for compressing the gas for storage in the reservoir;

an auxiliary tank for storing a second fluid to be heated, wherein the second fluid is heated with heat generated from compression of the gas by the compressor; and

a second medium voltage electrical heat exchanger for heating the second fluid in the auxiliary tank, wherein the second medium voltage electrical heat exchanger comprises one or more medium voltage heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive.

7. The energy storage system of claim 3, wherein the reservoir comprises a tank.

8. The energy storage system of claim 3, wherein the reservoir comprises an underground cavern.

9. The energy storage system of claim 4, wherein the medium voltage electrical heat exchanger is powered by one or more photovoltaic panels.

10. The energy storage system of claim 4, further comprising a concentrated solar power receiver for heating the molten salt, and wherein:

the first tank stores the molten salt heated in the concentrated solar power receiver; and

the medium voltage electrical heat exchanger is for heating the molten salt in the first tank.

11. The energy storage system of claim 5, wherein the reservoir is part of a pulverized coal-fired boiler.

12. The energy storage system of claim 6, wherein the second medium voltage electrical heat exchanger is powered by a renewable energy source.

13. The energy storage system of claim 9, the medium voltage electrical heat exchanger is powered by DC voltage from the one or more photovoltaic panels without converting the DC voltage to AC voltage.

14. The energy storage system of claim 10, further comprising:

a steam generator for generating steam with the molten salt in the first tank;

a second tank for storing the molten salt after the molten salt is used to generate the steam,

wherein the molten salt in the second tank is fed to the concentrated solar power receiver for solar heating; and

a second medium voltage electrical heat exchanger for heating the molten salt in the second tank, wherein the second medium voltage electrical heat exchanger comprises one or more medium voltage resistive heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive.

15. The energy storage system of claim 12, wherein the renewable energy source comprises a wind-powered renewable energy source.

16. The energy storage system of claim 15, further comprising an additional heat exchanger for heating the compressed gas prior to heating by the medium voltage electrical heat exchanger, wherein the additional heat exchanger uses heat from the second medium to heat the compressed gas.

17. The energy storage system of claim 14, wherein the first and second medium voltage electrical heat exchangers are powered by a wind-power energy system.

18. A method for storing energy comprising:

storing a fluid for heating in a reservoir;

heating the fluid with a medium voltage electrical heat exchanger connected to the reservoir, wherein the medium voltage electrical heat exchanger comprises one or more medium voltage resistive heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive, and wherein the one or more medium voltage resistive heating elements each comprise;

an outer metal sheath;

a resistive wire; and

a dielectric core positioned within the outer metal sheath, wherein the dielectric core comprises;

a first series of two or more axially-aligned, outer tubular dielectric bodies positioned end-to-end; and

a second series of two or more axially-aligned, inner tubular dielectric bodies,

wherein;

the inner tubular dielectric bodies are positioned end-to-end in the sheath and are nested inside the outer tubular dielectric bodies;

the inner tubular dielectric bodies define an interior passageway and the resistive wire is positioned in the interior passageway; and

the inner tubular dielectric bodies are longitudinally staggered relative to the outer tubular dielectric bodies;

driving a turbine by the heated fluid; and

generating electricity with an electrical generator that is connected to the turbine.

19. The method of claim 18, further comprising powering the medium voltage electrical heat exchanger with a renewable energy source that supplies the voltage between 601 V and 69,000 V, inclusive, to the medium voltage resistive heating elements of the medium voltage electrical heat exchanger to heat the fluid.

20. The method of claim 18, wherein:

the reservoir comprises compressed gas as the fluid; and

the compressed gas from the reservoir flows to the medium voltage electrical heat exchanger, whereupon the medium voltage electrical heat exchanger heats the gas upon decompression of the gas; and

the turbine is powered by flow of the decompressed gas.

21. The method of claim 18, wherein storing the fluid for heating in a reservoir comprises storing molten salt in a reservoir that comprises a first tank.

22. The method of claim 19, wherein the renewable energy source comprises a wind-powered renewable energy source.

23. The method of claim 20, further comprising:

compressing the gas for storage in the reservoir with a compressor;

storing a second fluid to be heated in an auxiliary tank, wherein the second fluid is heated with heat generated from compression of the gas by the compressor; and

heating the second fluid in the auxiliary tank with a second medium voltage electrical heat exchanger, wherein the second medium voltage electrical heat exchanger comprises one or more medium voltage heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive.

24. The method of claim 21, further comprising powering the medium voltage electrical heat exchanger with one or more photovoltaic panels.

25. The method of claim 21, further comprising heating the molten salt in a concentrated solar power receiver for, and wherein:

the first tank stores the molten salt heated in the concentrated solar power receiver; and

the medium voltage electrical heat exchanger is for heating the molten salt in the first tank.

26. The method of claim 23, wherein the second medium voltage electrical heat exchanger is powered by a wind-powered renewable energy source.

27. The method of claim 25, further comprising:

generating steam by a steam generator using the molten salt in the first tank;

storing the molten salt in a second tank after the molten salt is used to generate the steam, wherein the molten salt in the second tank is fed to the concentrated solar power receiver for solar heating; and

heating the molten salt in the second tank with a second medium voltage electrical heat exchanger, wherein the second medium voltage electrical heat exchanger comprises one or more medium voltage resistive heating elements, wherein each of the medium voltage resistive heating elements is driven with a voltage between 601 V and 69,000 V, inclusive.

28. The method of claim 26, further comprising heating the compressed gas with an additional heat exchanger for prior to heating by the medium voltage electrical heat exchanger, wherein the additional heat exchanger uses heat from the second medium to heat the compressed gas.

29. The method of claim 27, further comprising powering the first and second medium voltage electrical heat exchangers with a wind-power energy system.