Systems and methods for optimizing thermal efficiencey of a compressed air energy storage system

A method of controlling the thermal efficiency of a compressed gas-based energy storage and recovery system, the compressed gas-based energy storage and recovery system including a gas compressor/expander device and a liquid management system,

• the gas compressor/expander device including a first pneumatic cylinder having a first pneumatic working piston disposed therein for reciprocating movement in the first pneumatic cylinder, the first pneumatic working piston dividing the first pneumatic cylinder into, and defining therewith, a first pneumatic chamber and a second pneumatic chamber, and a second pneumatic cylinder having a second pneumatic working piston disposed therein for reciprocating movement in the second pneumatic cylinder, the second pneumatic working piston dividing the second pneumatic cylinder into, and defining therewith, a third pneumatic chamber and a fourth pneumatic chamber,
• the liquid management system including a first hydraulic cylinder having a first hydraulic working piston disposed therein for reciprocating movement in the first hydraulic cylinder, the first hydraulic working piston dividing the first hydraulic cylinder into, and defining therewith, a first hydraulic chamber and a second hydraulic chamber, a second hydraulic cylinder having a second hydraulic working piston disposed therein for reciprocating movement in the second hydraulic cylinder, the second hydraulic working piston dividing the second hydraulic cylinder into, and defining therewith, a third hydraulic chamber and a fourth hydraulic chamber,
• the method comprising:
• fluidically isolating the first pneumatic chamber from a gas source;
• establishing fluid communication between the second pneumatic chamber and the gas source;
• fluidically isolating the first hydraulic chamber from a liquid storage structure;
• establishing fluid communication between the first hydraulic chamber and the first pneumatic chamber;
• fluidically isolating the second hydraulic chamber from the second pneumatic chamber;
• establishing fluid communication between the second hydraulic chamber and the liquid storage structure;
• moving the first pneumatic working piston in a first direction to:
• a) reduce the volume of the first pneumatic chamber and compress a first mass of gas contained therein from a first pressure to a second pressure higher than the first pressure, and b) increase the volume of the second pneumatic chamber and receive therein a second mass of gas at a third pressure from the gas source;
• and
• moving the first hydraulic working piston in a second direction to:
• a) reduce the volume of the first hydraulic chamber and displace a first volume of liquid contained therein to the first pneumatic chamber and contact the first mass of gas to cause heat energy produced by the compression of the first mass of gas to be transferred from the first mass of gas to the first volume of liquid, and b) increase the volume of the second hydraulic chamber and receive therein a second volume of liquid from the liquid storage structure.

A method of controlling the thermal efficiency of a compressed gas-based energy storage and recovery system, the compressed gas-based energy storage and recovery system including a gas compressor/expander device and a liquid management system,

• the gas compressor/expander device including a first pneumatic cylinder having a first pneumatic working piston disposed therein for reciprocating movement in the first pneumatic cylinder, the first pneumatic working piston dividing the first pneumatic cylinder into, and defining therewith, a first pneumatic chamber and a second pneumatic chamber, and a second pneumatic cylinder having a second pneumatic working piston disposed therein for reciprocating movement in the second pneumatic cylinder, the second pneumatic working piston dividing the second pneumatic cylinder into, and defining therewith, a third pneumatic chamber and a fourth pneumatic chamber,
• the liquid management system including a first hydraulic cylinder having a first hydraulic working piston disposed therein for reciprocating movement in the first hydraulic cylinder, the first hydraulic working piston dividing the first hydraulic cylinder into, and defining therewith, a first hydraulic chamber and a second hydraulic chamber, a second hydraulic cylinder having a second hydraulic working piston disposed therein for reciprocating movement in the second hydraulic cylinder, the second hydraulic working piston dividing the second hydraulic cylinder into, and defining therewith, a third hydraulic chamber and a fourth hydraulic chamber,
• the method comprising:
• fluidically isolating the third pneumatic chamber from a gas storage chamber;
• establishing fluid communication between the fourth pneumatic chamber and the gas storage chamber;
• fluidically isolating the fourth hydraulic chamber from a liquid storage structure;
• establishing fluid communication between the fourth hydraulic chamber and the third pneumatic chamber;
• fluidically isolating the third hydraulic chamber from the fourth pneumatic chamber;
• establishing fluid communication between the third hydraulic chamber and the liquid storage structure;
• moving the second pneumatic working piston in a first direction to:
• a) increase the volume of the fourth pneumatic chamber and receive therein a first mass of gas at a first pressure from the gas storage chamber and allow the first mass of gas contained therein to expand from the first pressure to a second pressure less than the first pressure, and b) reduce the volume of the third pneumatic chamber, wherein the third pneumatic chamber includes a second mass of gas that has expanded from a third pressure to a fourth pressure less than the third pressure;
• and
• moving the second hydraulic working piston in a second direction to:
• a) reduce the volume of the fourth hydraulic chamber and displace a first volume of liquid contained therein to the third pneumatic chamber and contact the second mass of gas contained in the third pneumatic chamber to cause the first volume of liquid to transfer heat energy to the second mass of gas, and b) increase the volume of the third hydraulic chamber and receive therein a second volume of liquid from the liquid storage structure.