Power generation and storage

A method of operating a combined cycle power generation and storage system the method comprising:

• storing power using a liquid air energy storage system by separating carbon dioxide from ambient air, liquefying the air, and storing the air in a liquid state;
• producing power by combustion of a carbon-based fuel in a combustion engine, along with an exhaust stream containing carbon dioxide;
• exchanging heat from the exhaust stream to air from the liquid air storage system, thereby producing a cooled exhaust stream and heated air;
• recovering power by expansion of the heated air;
• and
• separating carbon dioxide from the cooled exhaust stream;
• wherein
• carbon dioxide is separated from the air and from the cooled exhaust stream using the same separation system, and
• the carbon dioxide is separated by cooling the cooled exhaust stream or ambient air using a reverse Brayton cycle.

A combined cycle power generation and storage system comprising:

• a liquid air energy storage system configured to use power to liquefy air and store it in a liquid state;
• a combustion engine configured to produce power by combustion of a carbon-based fuel along with an exhaust stream containing carbon dioxide;
• a heat recovery system configured to exchange heat from the exhaust stream to air from the liquid air storage system, and thereby produce a cooled exhaust stream and heated air;
• an air expansion machine configured to recover power by expansion of heated air from the heat recovery system;
• and
• a separation system configured to separate carbon dioxide from ambient air prior to liquefaction during operation of the liquid air energy storage system, and to separate carbon dioxide from the cooled exhaust stream during operation of the combustion engine prior to emission of the cooled exhaust stream to atmosphere, wherein
• the combustion engine comprises an intercooled compression system configured to reject heat to air in the heat recovery system.