Methods for storing gas

1. A method for storing a gas, the method comprising:

positioning a gas storage system under water, the gas storage system having a gas inlet;

injecting gas through the gas inlet into the gas storage system, wherein the gas is compressed; and

disposing a flexible containment bag between the gas and water in the gas storage system.

2. The method of claim 1 , wherein the gas storage system is positioned on a sea floor.

3. The method of claim 1 , wherein the gas storage system is greater than 3,000 feet below a surface of the water.

4. The method of claim 1 , further comprising:

flowing water into the gas storage system though a water inlet, wherein the water inlet is deeper than the gas inlet; and

compressing gas in the gas storage system with the hydrostatic force of the water entering the gas storage system.

5. A method for storing a gas, the method comprising:

positioning a gas storage system under water, the gas storage system having a gas inlet;

injecting gas through the gas inlet into the gas storage system, wherein the gas is compressed; and

anchoring the gas storage system to a sea floor, wherein the anchoring comprises:

disposing a mud mat over the sea floor;

depositing solid ballast within a containment structure coupled to the gas storage system; and

controlling the buoyancy of the solid ballast to maintain engagement of the containment structure with the mud mat.

6. The method of claim 5 , further comprising disposing a floating member between the gas and the water in the gas storage system, wherein the floating member has a density less than the water.

7. The method of claim 5 , further comprising disposing a flexible containment bag between the gas and the water in the gas storage system.

8. A method for storing a gas, the method comprising:

positioning a gas storage system under water, the gas storage system having a vessel with a lower end at a first water depth, a gas inlet, and a water port having a water depth greater than a water depth of the gas inlet;

injecting gas through the gas inlet into the vessel;

allowing water to freely flow into the vessel through the water port; and

compressing the gas in the vessel, wherein a pressure of the gas proximate the lower end is substantially equal to a hydrostatic pressure of the water at the first water depth and a pressure of the gas at a second water depth less than the first water depth is independent of a hydrostatic pressure of the water at the second water depth.

9. The method of claim 8 , further comprising disposing a floating member between the gas and the water in the vessel, wherein the floating member has a density less than the water.

10. The method of claim 9 , further comprising disposing a flexible containment bag between the gas and the water in the vessel.

11. The method of claim 8 , further comprising anchoring the gas storage system to a sea floor.

12. The method of claim 11 , wherein the anchoring comprises:

disposing a mud mat over the sea floor;

depositing solid ballast within a containment structure coupled to the gas storage system; and

controlling the buoyancy of the solid ballast to maintain engagement of the containment structure with the mud mat.

13. A method for dispensing gas, the method comprising:

placing a gas storage system under water, the gas storage system having at least one gas port;

injecting gas through a gas inlet into the gas storage system, wherein the gas is compressed;

venting the compressed gas through the at least one gas port;

coupling a storage facility to the at least one gas port;

receiving the compressed gas vented through the at least one gas port within the storage facility; and

coupling a control and monitoring system to the gas storage system and the storage facility, the control and monitoring system configured to monitor and control the rate of the compressed gas vented to the storage facility.

14. The method of claim 13 , wherein the storage facility is one of the group consisting of a marine riser and a ship.

15. The method of claim 13 , further comprising cleaning the compressed gas prior to the venting.

16. The method of claim 15 , wherein the cleaning comprises:

disposing a separator proximate a deepest end of the gas storage system;

collecting at least one of particulates and liquids; and

discharging the at least one of particulates and liquids from the gas storage system through a discharge port.

17. The method of claim 13 , further comprising coupling a valve to the at least one gas port configured to control the pressure of the vented compressed gas.