Energy storage system and method for energy storage

1. An energy storage system, the energy storage system comprising:

a compressor for compressing a gas,

a thermal energy storage for cooling the gas coming from the compressor to a given temperature by heating a thermal storage medium to store thermal energy,

a heat recuperator for further cooling the gas coming from the compressor, and

a reservoir for storing the compressed gas that has been cooled in the heat recuperator,

wherein the compressed gas is further cooled below the given temperature by heating the gas supplied to the compressor using the heat recuperator.

2. The energy storage system according to claim 1 , wherein the thermal energy storage includes:

a plurality of thermal energy storages,

and further comprising another compressor connected to an outlet of one of the plurality of thermal energy storages and an inlet of another of the plurality of thermal energy storages, the another compressor for compressing the gas.

3. The energy storage system according to claim 2 , wherein the thermal storage medium passes through the thermal energy storages in parallel.

4. The energy storage system according to claim 2 , wherein each of the plurality of thermal energy storages has a heat exchanger and common hot tanks and cold tanks.

5. The energy storage system according to claim 1 , further comprising another compressor connected between the heat recuperator and the reservoir.

6. The energy storage system according to claim 1 , further comprising:

a turbine connected between the thermal energy storage and the heat recuperator, whereby the turbine is provided for expanding the gas coming from the reservoir and heated in the heat recuperator and thermal energy storage.

7. The energy storage system according to claim 2 , further comprising a plurality of turbines, each turbine connected to an outlet of one of the plurality of thermal energy storages and an inlet of another of the plurality of thermal energy storages, whereby each turbine is provided for expanding the gas contained in the reservoir.

8. The energy storage system according to claim 2 , further comprising a plurality of turbines, wherein each turbine of the plurality of turbines is provided in parallel with one of the compressor and the another compressor.

9. The energy storage system according to claim 1 , wherein the thermal storage medium includes molten salt.

10. The energy storage system according to claim 1 , wherein the given temperature is comprised in the range 280-320° C. and preferably it is about 300° C.

11. The energy storage system according to claim 1 , wherein the heat recuperator has path connected to the thermal energy storage and another path connected to the compressor.

12. A method for energy storage comprising

compressing a gas in a compressor,

cooling the gas coming from the compressor to a given temperature by heating a thermal storage medium to store thermal energy,

further cooling the compressed gas coming from the compressor below the given temperature by heating the gas supplied to the compressor using a heat recuperator, and

storing the compressed gas after the further cooling of the compressed gas by the heat recuperator.

13. The method of claim 12 , wherein cooling the gas comprises a plurality of cooling steps, and compressing the gas between the cooling steps.

14. A method for energy storage comprising:

extracting a compressed gas from a reservoir,

heating the gas coming from the reservoir by cooling a thermal storage medium to recover thermal energy in a thermal energy storage,

expanding the gas in a turbine and discharging the gas,

heating the compressed gas coming from the reservoir to a given temperature by cooling the gas discharged from the turbine using a heat recuperator, and

conveying the gas discharged from the turbine to the thermal energy storage.

15. The method of claim 14 , wherein heating the gas from the reservoir by cooling the thermal storage medium comprises a plurality of heating steps, and expanding the gas between the steps of the plurality of heating steps.