The compressed air energy storage system stores excess electric energy through compressed air, and when needed, releases high-pressure air and generates power through a turbine. When storing energy, the compressor in the system consumes electric energy to compress the air and store it in the air storage chamber; when discharging energy, high-pressure air is released from the gas storage chamber, enters the combustion chamber of the gas turbine and burns with fuel, and drives the turbine to generate power. In the process of energy release, since no compressor consumes the output work of the turbine, compared with the gas turbine system consuming the same fuel, the compressed air energy storage system can generate more than twice the power, so as to realize the conversion between compressed air energy and power.
Since Stal Laval proposed the use of underground caves to realize compressed air energy storage in 1949, two large power stations have been put into commercial operation in Huntorf in Germany and Mclntosh in the United States for more than 20 years. Because traditional compressed air energy storage systems require large-scale gas storage devices and burning fossil fuels, this has largely limited the popularization and application of this technology. In order to solve the main problems faced by conventional compressed air energy storage systems, some improved technologies have emerged internationally, including
(1) Advanced adiabatic compressed air energy storage system (AACAESS). The system stores the compression heat in the air compression process in the heat storage device, and recovers this part of the compression heat during the energy release process. The energy storage efficiency of the system can be greatly improved, which can reach more than 70% in theory.
(2) Small compressed air energy storage system. The scale is generally at the 10MW level. It uses an above-ground high-pressure container to store compressed air, which breaks through the dependence of large traditional compressed air power stations on gas storage caves and has greater flexibility.
(3) Miniature compressed air energy storage system. The scale is generally in the order of several kW to tens of kW. It also uses high-pressure containers on the ground to store compressed air, which is mainly used for backup power in special fields (such as control, communications, and military fields), micro-small power grids in remote and isolated areas, and compressed air vehicle power.
(4) Liquefied air and supercritical compressed air energy storage system. This is a new type of compressed air energy storage system that has only recently been proposed. Since the density of liquid air is much greater than that of gaseous air, the system does not require a large air storage chamber. The Institute of Engineering Thermophysics of the Chinese Academy of Sciences first proposed and independently developed a supercritical compressed air energy storage system in 2009, which further improved the energy efficiency of the system.
In recent years, compressed air energy storage has been further developed globally. The largest projects include a 2700MW compressed air energy storage system in Ohio, USA, which began construction in 2001, and a 300MW compressed air energy storage project in Iowa that is under planning and construction. Although China started late in the research and development of compressed air energy storage systems, the compressed air energy storage systems have been highly valued by relevant scientific research institutes, power companies and government departments.