SYSTEMS AND METHODS FOR REDUCING DEAD VOLUME IN COMPRESSED-GAS ENERGY STORAGE SYSTEMS
In various embodiments, dead space and associated coupling losses are reduced in energy storage and recovery systems employing compressed air.
1 .- 47 . (canceled)
48 . A method of energy recovery, the method comprising:
admitting compressed gas at a first pressure into a first cylinder assembly;
expanding gas within the first cylinder assembly from approximately the first pressure to an intermediate pressure lower than the first pressure;
exhausting gas at the intermediate pressure from the first cylinder assembly into a mid-pressure reservoir;
admitting gas at the intermediate pressure from the mid-pressure reservoir into a second cylinder assembly;
expanding gas within the second cylinder assembly from approximately the intermediate pressure to a second pressure lower than the intermediate pressure; and
exhausting gas at the second pressure from the second cylinder assembly.
49 . The method of claim 48 , wherein compressed gas is admitted into the first cylinder assembly from a compressed-gas reservoir different from the mid-pressure reservoir.
50 . The method of claim 49 , wherein the compressed-gas reservoir comprises one or more pressure vessels.
51 . The method of claim 49 , wherein the compressed-gas reservoir comprises a cavern.
52 . The method of claim 48 , further comprising exchanging heat between gas and heat-exchange liquid during expansion in the first cylinder assembly.
53 . The method of claim 48 , further comprising exchanging heat between gas and heat-exchange liquid during expansion in the second cylinder assembly.
54 . The method of claim 48 , further comprising exchanging heat between gas and heat-exchange liquid during expansion in the first and second cylinder assemblies.
55 . The method of claim 48 , further comprising mingling heat-exchange liquid with gas within the mid-pressure reservoir.
56 . The method of claim 55 , wherein mingling heat-exchange liquid with gas comprises spraying heat-exchange liquid into gas.
57 . The method of claim 48 , wherein gas is exhausted at the second pressure from the second cylinder assembly to a vent to atmosphere.
58 . The method of claim 48 , wherein expansion of gas within the first cylinder assembly is substantially isothermal.
59 . The method of claim 48 , wherein expansion of gas within the second cylinder assembly is substantially isothermal.
60 . The method of claim 48 , wherein the mid-pressure reservoir comprises a pressure-compensated vessel.
61 . The method of claim 48 , wherein the mid-pressure reservoir has a volume sufficient to supply gas to an interior volume of the second cylinder assembly while maintaining a substantially constant pressure within the mid-pressure reservoir.
62 . The method of claim 48 , wherein expansion of gas within the first cylinder assembly translates a boundary mechanism within the first cylinder assembly.
63 . The method of claim 62 , further comprising converting motion of the boundary mechanism into rotary motion.
64 . The method of claim 63 , wherein the motion of the boundary mechanism is converted into rotary motion via a crankshaft.
65 . The method of claim 48 , wherein potential energy of gas expanding in at least one of the first or second cylinder assemblies is utilized to produce electricity.
66 . The method of claim 48 , wherein the mid-pressure reservoir comprises a spray mechanism therewithin for spraying heat-exchange liquid.