Energy storage system using supercritical air

An energy storage system using supercritical air, comprising a compressor unit, a heat exchanger and storage device, a cold exchanger and storage device, a cryogenic tank, a throttling valve, at least one cryogenic pump, an expander unit, a generator, and a driver unit, wherein:

• the compressor unit includes at least one low-pressure compressor and at least one high-pressure compressor, the compressors being connected in series or integrated into a multistage compressor, and an inlet of each of the low-pressure compressors being connected to an air intake duct;
• the expander unit includes at least one low-pressure expander and at least one high-pressure expander, the expanders being connected in series or integrated into a multistage expander, and an outlet of the low-pressure expanders being connected to an air outlet duct;
• a driving shaft of the driver unit is coupled to a driven shaft of the compressor unit and a driven shaft of the generator is coupled to a driving shaft of the expander unit;
• the at least one low-pressure compressor and the at least one high-pressure compressor are connected to the heat exchanger and storage device;
• the heat exchanger and storage device, the cold exchanger and storage device and the cryogenic tank are connected in sequence;
• the throttling valve is provided between the cold exchanger and storage device and the cryogenic tank;
• the throttling valve and the at least one cryogenic pump are located between the cryogenic tank and the cold storage and exchanger device with the throttling valve being disposed upstream to the cryogenic tank;
• the heat exchanger and storage device is connected to the at least one low-pressure expander and the at least one high-pressure expander;
• during the period of energy storage, electricity is used to drive the compressor unit and pressurize air to a supercritical air, and the compression heat is recovered and stored in the heat exchanger and storage device;
• the supercritical air is then introduced into the cold exchanger/storage device where it is cooled down to a low temperature by extracting the cold storage in the cold exchanger/storage device, and the cooled air stream then expands via the throttling valve where a vast majority of the air stream is liquefied and stored in cryogenic tank;
• during the period of energy release, liquid air is pumped into the cold exchanger and storage device where it is heated isobarically and becomes the supercritical air, and at the same time, cold energy contained by the supercritical air is extracted and stored in the cold exchanger/storage device;
• the supercritical air is further heated by using the compression heat stored in the heat exchanger/storage device;
• the heated air is expanded through the expander unit to drive the electric generator;
• and
• the throttling valve is further provided to throttle the pressurized air for supplying additional cold energy when cold energy is not enough;
• wherein, the cold air is converted into a wet vapor state by throttling, upon which saturated liquid air is the major component and the remaining saturated vapor flows back into the cold exchanger and storage device.