Systems and methods for compressing and/or expanding a gas utilizing a bi-directional piston and hydraulic actuator

A system for increasing the efficiency of a compressed gas-based energy storage and recovery system, the system comprising:

• a first pneumatic cylinder having a first working piston disposed therein for reciprocating movement in the first pneumatic cylinder, the first working piston dividing the first pneumatic cylinder into, and defining therewith, a first pneumatic chamber and a second pneumatic chamber,
• the first pneumatic chamber having a first fluid port and a second fluid port, the first fluid port fluidically coupleable to a gas source,
• the second pneumatic chamber having a first fluid port and a second fluid port, the first fluid port fluidically coupleable to the gas source;
• a second pneumatic cylinder having a second working piston disposed therein for reciprocating movement in the second pneumatic cylinder, the second working piston dividing the second pneumatic cylinder into, and defining therewith, a third pneumatic chamber and a fourth pneumatic chamber,
• the third pneumatic chamber having a first fluid port and a second fluid port, the first fluid port fluidically coupleable to the second fluid port of the first pneumatic chamber and the second fluid port fluidically coupleable to a compressed gas storage chamber,
• the fourth pneumatic chamber having a first fluid port and a second fluid port, the first fluid port fluidically coupleable to the second fluid port of the second pneumatic chamber and the second fluid port fluidically coupleable to the compressed gas storage chamber;
• a first hydraulic actuator coupled to the first working piston;
• a second hydraulic actuator coupled to the second working piston;
• and
• a hydraulic controller fluidically coupleable to the first hydraulic actuator and the second hydraulic actuator, the hydraulic controller operable in a compression mode in which the second hydraulic actuator causes gas to be discharged from the second pneumatic cylinder to the compressed gas storage chamber at a higher pressure than it enters the first pneumatic cylinder from the gas source, and an expansion mode in which gas in the first pneumatic cylinder does work on the first hydraulic actuator and is discharged from the first pneumatic cylinder to the gas source at a lower pressure than it enters the second pneumatic cylinder from the compressed gas storage chamber,
• wherein operation of the hydraulic controller in the compression mode produces a first hydraulic actuator force on the first working piston sufficient to move the first working piston:
• a) in a first direction such that gas contained in the first pneumatic chamber is discharged from the first pneumatic chamber into the third pneumatic chamber, and b) in a second direction, opposite the first direction, such that gas contained in the second pneumatic chamber is discharged from the second pneumatic chamber into the fourth pneumatic chamber and produces a second hydraulic actuator force on the second working piston sufficient to move the second working piston:
• a) in a third direction such that gas contained in the third pneumatic chamber is discharged from the third pneumatic chamber into the compressed gas storage chamber, and b) in a fourth direction, opposite the third direction, such that gas contained in the fourth pneumatic chamber is discharged from the fourth pneumatic chamber into the compressed gas storage chamber.