Compressed gas energy storage and restitution system and method

1. A compressed gas energy storage and restoration system comprising:

at least one gas compressor for compressing gas with each gas compressor providing heated compressed gas;

at least one compressed gas storage for storing compressed gas from the at least one gas compressor from which heat produced by compression has been removed;

at least one heat storage, each heat storage storing heat absorbed from the heated compressed gas, the at least one heat storage comprising a staged arrangement containing particles of a phase change material disposed in at least two fixed beds, at least two adjacent fixed beds of the staged arrangement containing particles of the phase change material with the particles of each adjacent fixed bed having a different melting point which creates a discontinuity in a thermal gradient disposed between the at least two adjacent beds and the particles of the phase change material of the at least one heat storage heating the compressed gas stored in the at least one compressed gas storage; and

at least one expander for producing energy from the compressed gas after heating of the stored compressed gas with the heat stored in the at least one heat storage; and wherein the at least two adjacent fixed beds of particles of the phase change material are separated by a wall permeable to the gas.

2. The system as claimed in claim 1 , wherein the discontinuity in the thermal gradient comprises a layer of a thermally insulating material separating at least two of the adjacent fixed beds of particles of the phase change material.

3. The system as claimed in claim 1 , wherein the discontinuity in the thermal gradient comprises a layer of a thermally insulating material separating the at least two of the adjacent fixed beds of particles of the phase change material.

4. The system as claimed in claim 1 , wherein the discontinuity in the thermal gradient is located between two fixed beds of the particles of the phase change material having different melting points.

5. The system as claimed in claim 1 , wherein the discontinuity in the thermal gradient is located between two fixed beds of the particles of the phase change material having different melting points.

6. The system as claimed in claim 2 , wherein the discontinuity in the thermal gradient is located between two fixed beds of the particles of the phase change material having different melting points.

7. The system as claimed in claim 3 , wherein the discontinuity in the thermal gradient is located between two fixed beds of the particles of the phase change material having different melting points.

8. The system as claimed in claim 4 , wherein the at least two of the fixed beds of particles of the phase change material having different melting points are respectively located at opposed ends of the at least one heat storage.

9. The system as claimed in claim 5 , wherein the at least two of the fixed beds of particles of the phase change material having different melting points are respectively located at opposed ends of the at least one heat storage.

10. The system as claimed in claim 6 , wherein the at least two of the fixed beds of particles of the phase change material having different melting points are respectively located at opposed ends of the at least one heat storage.

11. The system as claimed in claim 7 , wherein the at least two of the fixed beds of the phase change material having different melting points are respectively located at opposed ends of the at least one heat storage.

12. The system as claimed in claim 1 comprising an axial passage extending through the at least one heat storage providing a path for compressed gas to flow through the fixed beds of phase change material of the at least one heat storage.

13. The system as claimed in claim 12 , wherein the at least one heat storage comprises gas injection means and gas withdrawal means located at a face of at least one stage of the staged arrangement of the at least two fixed beds of particles of the phase change material.

14. The system as claimed in claim 13 in which the gas injection means, and the withdrawal means comprise a distribution grating located between two fixed beds of particles of the phase change material.

15. The system as claimed in claim 14 , comprising a layer of a thermally insulating material contacting one face of the distribution grating.

16. A compressed gas energy storage and restoration method comprising:

compressing gas with at least one compressor to provide heated compressed gas which is stored in at least one compressed gas storage after heat has been removed from the heated compressed gas;

storing the heat absorbed from the heated compressed gas in at least one heat storage, the at least heat storage comprising a staged arrangement containing particles of a phase change material disposed in at least two fixed beds, at least two adjacent fixed beds of the staged arrangement containing particles of the phase change material with the particles of each adjacent bed having a different melting point which creates a discontinuity in a thermal gradient disposed between the at least two adjacent beds and the particles of the phase change material of the at least one heat storage;

heating the compressed gas with the heat stored in the at least one heat storage; and

expanding the heated compressed gas with at least one expander to produce energy; and wherein the at least two adjacent fixed beds of particles of the phase change material are separated by a wall permeable to the gas.

17. The method as claimed in claim 16 , wherein the compressed gas is injected into and withdrawn from ends of the at least one heat storage.

18. The method as claimed in claim 16 , wherein compressed gas is injected into and withdrawal from at least one intermediate fixed bed of the phase change particles of the at least one heat storage.

19. The method as claimed in claim 16 , comprising:

storing heat in a first portion of the at least one fixed bed of the phase change particles of the at least one heat storage by a first heat exchange between the heated compressed gas and the phase change particles;

storing heat in a second portion of the at least one fixed bed by a second heat exchange between the compressed gas and the phase change particles; and

recovering heat stored in the first and second portions by heating the compressed gas by heat exchange between the first and second portions of the phase change particles and then expanding the heated compressed to generate the energy.

20. The method as claimed in claim 17 , comprising:

storing heat in a first portion of the at least one fixed bed of the phase change particles of the at least one heat storage by a first heat exchange between the heated compressed gas and the phase change particles;

storing heat in a second portion of the at least one fixed bed by a second heat exchange between the compressed gas and the phase change particles; and

recovering heat stored in the first and second portions by heating the compressed gas by heat exchange between the first and second portions of the phase change particles and then expanding the heated compressed to generate the energy.

21. The method as claimed in claim 18 , comprising:

storing heat in a first portion of the at least one fixed bed of the phase change particles of the at least one heat storage by a first heat exchange between the heated compressed gas and the phase change particles;

storing heat in a second portion of the at least one fixed bed by a second heat exchange between the compressed gas and the phase change particles; and

recovering heat stored in the first and second portions by heating the compressed gas by heat exchange between the first and second portions of the phase change particles and then expanding the heated compressed to generate the energy.