Grid scale energy storage systems using reheated air turbine or gas turbine expanders

1. A method of operating a compressed aft energy storage system associated with a gas turbine power plant, the compressed aft energy storage system having an aft storage tank in fluid communication with a multi-stage compressor, the multi-stage compressor comprising a low pressure compressor having an intercooler associated therewith and a high pressure compressor, the method comprising:

operating the compressed aft energy storage system in an energy storage mode by:

compressing ambient air in the low pressure compressor, cooling the compressed aft using the intercooler, and then compressing the compressed aft in the high pressure compressor to generate a first compressed air flow; and

directing the first compressed air flow from the high-pressure compressor to the air storage tank;

operating the compressed aft energy storage system in an aft injection mode by:

compressing ambient aft in the low pressure compressor to generate a second compressed air flow and heating the second compressed air flow in a heater such that the second compressed air flow bypasses each of the intercooler and the high pressure compressor;

directing the first compressed air flow from the air storage tank-through each of a first heater and an expander to generate a first air flow; and,

injecting into a compressor discharge plenum of a gas turbine engine of the gas turbine power plant: (a) the first aft flow; and (b) the heated second compressed aft flow;

wherein:

a pressure of the second compressed aft flow exiting the low pressure compressor is greater than a pressure of air in the compressor discharge plenum;

a temperature of the heated second compressed air flow is approximately equal to a temperature of air in the compressor discharge plenum; and

an operating pressure of the air storage tank is maintained using a corrosion inhibiting incompressible fluid.

2. The method of claim 1 , wherein the corrosion inhibiting incompressible fluid is treated water.

3. The method of claim 2 , further comprising providing a preheater upstream of the first heater.

4. The method of claim 2 , wherein the expander is a multi-stage expander.

5. The method of claim 4 , further comprising providing a heater between each stage of the multi-stage expander.

6. The method of claim 1 , further comprising mixing the first air flow and the heated second compressed air flow prior to injection.

7. The method of claim 1 , further comprising coupling each of the gas turbine engine and the expander to a separate generator.

8. A method of operating a compressed air energy storage system associated with a gas turbine power plant, the compressed aft energy storage system having an air storage tank in fluid communication with a multi-stage compressor, the multi-stage compressor comprising a low pressure compressor having an interceder associated therewith and a high pressure compressor, the method comprising:

operating the compressed air energy storage system in an energy storage mode by:

compressing ambient air in the low pressure compressor, cooling the compressed aft using the intercooler, and then compressing the compressed air in the high pressure compressor to generate a first compressed aft flow; and

directing the first compressed aft flow from the high-pressure compressor to the air storage tank;

operating the compressed aft energy storage system in an aft injection mode by:

compressing ambient air in the low pressure compressor to generate a second compressed aft flow and heating the second compressed aft flow in a heater such that the second compressed aft flow bypasses each of the intercooler and the high pressure compressor;

directing the first compressed aft flow from the air storage tank through each of a first heater and an expander to generate a first aft flow; and,

injecting into a compressor discharge plenum of a gas turbine engine of the gas turbine power plant: (a) the first air flow; and (b) the heated second compressed aft flow;

wherein:

a pressure of the second compressed aft flow exiting the low pressure compressor is greater than a pressure of aft in the compressor discharge plenum; and

a temperature of the heated second compressed air flow is approximately equal to a temperature of air in the compressor discharge plenum.

9. The method of claim 8 , further comprising providing a preheater upstream of the first heater.

10. The method of claim 9 , wherein the expander is a multi-stage expander.

11. The method of claim 10 , further comprising providing a heater between each stage of the multi-stage expander.

12. The method of claim 11 , further comprising mixing the first air flow and the heated second compressed air flow prior to injection.

13. The method of claim 11 , further comprising coupling each of the gas turbine engine and the expander to a separate generator.

14. A method of operating a compressed air energy storage system associated with a gas turbine power plant, the compressed aft energy storage system having an air storage tank in fluid communication with a multi-stage compressor, the multi-stage compressor comprising a low pressure compressor having an intercooler associated therewith and a high pressure compressor, the method comprising:

operating the compressed air energy storage system in an energy storage mode by:

compressing aft in the low pressure compressor, cooling the compressed aft using the intercooler, and then compressing the compressed air in the high pressure compressor to generate a first compressed aft flow; and

directing the first compressed aft flow from the high-pressure compressor to the aft storage tank;

operating the compressed air energy storage system in an air injection mode by:

compressing aft in the low pressure compressor to generate a second compressed air flow, the second compressed air flow bypassing each of the interceder and the high pressure compressor;

directing the first compressed air flow from the air storage tank through each of a first heater and an expander to generate a first air flow; and,

injecting into a compressor discharge plenum of a gas turbine engine of the gas turbine power plant at least one of: (a) the first aft flow; and (b) the second compressed air flow;

wherein:

a pressure of the second compressed aft flow exiting the low pressure compressor is greater than a pressure of air in the compressor discharge plenum.