Systems and methods for energy storage and recovery using rapid isothermal gas expansion and compression

Abstract

The invention relates to systems and methods for rapidly and isothermally expanding and compressing gas in energy storage and recovery systems that use open-air hydraulic-pneumatic cylinder assemblies, such as an accumulator and an intensifier in communication with a high-pressure gas storage reservoir on a gas-side of the circuits and a combination fluid motor/pump, coupled to a combination electric generator/motor on the fluid side of the circuits. The systems use heat transfer subsystems in communication with at least one of the cylinder assemblies or reservoir to thermally condition the gas being expanded or compressed.

What is claimed is: 
     
         1 .- 20 . (canceled) 
     
     
         21 . A method of energy storage utilizing compressed gas, the method comprising:
 admitting gas into a first cylinder assembly at a first pressure;   compressing gas within the first cylinder assembly from approximately the first pressure to a second pressure larger than the first pressure;   during compression within the first cylinder assembly, introducing a spray of discrete droplets of heat-transfer liquid within the first cylinder assembly, heat being exchanged between the gas and the heat-transfer liquid;   transferring gas at approximately the second pressure to a second cylinder assembly;   compressing gas within the second cylinder assembly from approximately the second pressure to a third pressure larger than the second pressure without introducing a spray of discrete droplets of heat-transfer liquid within the second cylinder assembly; and   thereafter, storing compressed gas within a compressed-gas storage reservoir.   
     
     
         22 . The method of  claim 21 , wherein admitting gas into the first cylinder comprises admitting ambient air into the first cylinder assembly. 
     
     
         23 . The method of  claim 21 , wherein the compressed-gas storage reservoir comprises one or more pressure vessels. 
     
     
         24 . The method of  claim 21 , wherein compression within the first cylinder assembly is substantially isothermal. 
     
     
         25 . The method of  claim 24 , wherein compression within the second cylinder assembly is substantially isothermal. 
     
     
         26 . The method of  claim 21 , further comprising controlling at least one of the compression in the first cylinder assembly or the compression in the second cylinder assembly based on at least one system parameter associated with operation of at least one of the first cylinder assembly or the second cylinder assembly. 
     
     
         27 . The method of  claim 26 , wherein the at least one system parameter comprises at least one of, within at least one of the first cylinder assembly or the second cylinder assembly, a fluid state, a fluid flow, a temperature, or a pressure. 
     
     
         28 . The method of  claim 26 , wherein the at least one system parameter comprises at least one of a position of a piston within the first cylinder assembly or a position of a piston within the second cylinder assembly. 
     
     
         29 . The method of  claim 21 , further comprising monitoring a gas temperature during at least one of compression in the first cylinder assembly or compression in the second cylinder assembly. 
     
     
         30 . The method of  claim 21 , further comprising monitoring a gas pressure during at least one of compression in the first cylinder assembly or compression in the second cylinder assembly. 
     
     
         31 . The method of  claim 21 , further comprising monitoring, during compression in the first cylinder assembly, at least one of a position or a rate of movement of a piston within the first cylinder assembly. 
     
     
         32 . The method of  claim 21 , further comprising monitoring, during compression in the second cylinder assembly, at least one of a position or a rate of movement of a piston within the second cylinder assembly. 
     
     
         33 . The method of  claim 21 , further comprising:
 admitting gas at approximately the third pressure into the second cylinder assembly;   expanding gas within the second cylinder assembly to approximately the second pressure;   transferring gas at approximately the second pressure to the first cylinder assembly;   expanding gas within the first cylinder assembly to approximately the first pressure; and   exhausting gas at approximately the first pressure from the first cylinder assembly.   
     
     
         34 . The method of  claim 33 , wherein expansion of gas in the second cylinder assembly is substantially isothermal. 
     
     
         35 . The method of  claim 34 , wherein expansion of gas in the first cylinder assembly is substantially isothermal. 
     
     
         36 . The method of  claim 33 , wherein exhausting gas from the first cylinder assembly comprises venting gas to an ambient atmosphere. 
     
     
         37 . The method of  claim 33 , wherein gas is admitted into the second cylinder assembly at approximately the third pressure from the compressed-gas storage reservoir.