Patent ID: 8677744

Claim:
A compressed gas energy storage and recovery system comprising: a cylinder assembly comprising (i) a first compartment, (ii) a second compartment, (iii) a piston, slidably disposed within the cylinder assembly, separating the compartments, and (iv) a piston rod coupled to the piston and extending outside the first compartment, the piston rod comprising a cavity (a) in fluid communication with the second compartment and (b) not fluidly connected to the first compartment; a compressed-gas storage reservoir; valving, selectively fluidly connecting the compressed-gas storage reservoir to the cylinder assembly, for admitting compressed gas into the second compartment for expansion or exhausting compressed gas from the second compartment after compression; a vent to atmosphere; valving, selectively fluidly connecting the vent to the cylinder assembly, for admitting gas into the second compartment for compression or exhausting expanded gas from the second compartment after expansion; a mechanism for introducing heat-exchange fluid within the second compartment; and a tube, configured for non-flexure and disposed at least partially within the cavity and in fluid communication with the mechanism, for facilitating recirculation of heat-exchange fluid from the second compartment to the cavity, from the cavity to the tube, from the tube to the mechanism, and from the mechanism to the second compartment.