Systems and methods for foam-based heat exchange during energy storage and recovery using compressed gas

Abstract

In various embodiments, foam is compressed to store energy and/or expanded to recover energy.

What is claimed is: 
     
         1 .- 44 . (canceled) 
     
     
         45 . An energy storage and recovery system comprising:
 a cylinder assembly for at least one of storing energy by compression or recovering energy by expansion;   a storage reservoir; and   selectively fluidly connected to the cylinder assembly and the storage reservoir, a mixing chamber for (i) receiving gas and heat-transfer liquid from the storage reservoir, (ii) mixing the gas with the heat-transfer liquid to form a foam, and (iii) transferring the foam to the cylinder assembly,   wherein the mixing chamber is selectively fluidly connected to the storage reservoir by (i) a first conduit for transferring gas and (ii) a second conduit, different from the first conduit, for transferring heat-transfer liquid.   
     
     
         46 . The system of  claim 45 , further comprising, within the mixing chamber, a mechanism for altering at least one characteristic of the foam. 
     
     
         47 . The system of  claim 46 , wherein the mechanism comprises at least one of a screen or a source of ultrasound energy. 
     
     
         48 . The system of  claim 46 , wherein the at least one characteristic comprises at least one of foam cell size or foam cell size uniformity. 
     
     
         49 . The system of  claim 45 , further comprising, coupled to at least one of the first conduit or the second conduit in the mixing chamber, a foam-generating mechanism. 
     
     
         50 . The system of  claim 49 , wherein the foam-generating mechanism comprises at least one of one or more nozzles, a rotating blade, a source of ultrasound energy, or a sparger. 
     
     
         51 . The system of  claim 45 , further comprising a second cylinder assembly for at least one of storing energy by compression or recovering energy by expansion over a pressure range different from a pressure range of the cylinder assembly. 
     
     
         52 . The system of  claim 51 , further comprising, selectively fluidly connected to the second cylinder assembly, a vent for exhausting expanded gas to atmosphere. 
     
     
         53 . The system of  claim 45 , further comprising a control system for controlling at least one of the cylinder assembly or the mixing chamber to enforce at least one of substantially isothermal compression or substantially isothermal expansion in the cylinder assembly. 
     
     
         54 . The system of  claim 53 , further comprising a sensor for detecting a pressure within at least one of the cylinder assembly or the mixing chamber, wherein the control system is responsive to the sensor. 
     
     
         55 . The system of  claim 54 , wherein the control system controls a flow rate of heat-transfer liquid into the mixing chamber in response to the detected pressure. 
     
     
         56 . The system of  claim 45 , further comprising a circulation apparatus for transferring heat-transfer liquid within the second conduit. 
     
     
         57 . The system of  claim 56 , wherein the circulation apparatus comprises a variable-speed pump. 
     
     
         58 . The system of  claim 45 , further comprising:
 (i) a movable boundary mechanism separating the cylinder assembly into two chambers, and   (ii) a crankshaft, mechanically coupled to the boundary mechanism, for converting reciprocal motion of the boundary mechanism into rotary motion.   
     
     
         59 . The system of  claim 58 , further comprising a motor/generator coupled to the crankshaft. 
     
     
         60 . The system of  claim 45 , wherein the storage reservoir comprises at least one of a pressure vessel, a pipe, or a cavern. 
     
     
         61 . The system of  claim 45 , wherein the first conduit also transfers liquid. 
     
     
         62 . The system of  claim 45 , wherein the second conduit also transfers gas. 
     
     
         63 .- 451 . (canceled)