As the growth of global demand for renewable energy continues, effectively storing and utilizing these intermittent energy sources has become a critical challenge. Adiabatic compressed air energy storage (A-CAES) offers a viable solution for balancing the fluctuations inherent in renewable energy. Improving its performance is essential for enabling the widespread adoption of renewable energy.

The constant volume air storage method is widely used in conventional A-CAES. However, it faces the drawback of low air storage density, especially when artificial tanks are used, which increases the number of tanks and causes capital costs to rise. Moreover, compression raises the temperature during the air charging process, resulting in decreased density and reduced air storage capacity. Conversely, during the air discharging process, expansion lowers the temperature, increasing density and reducing the amount of released air. These two processes significantly decrease the effective air usage of the tanks.

In a study published in Renewable and Sustainable Energy Reviews, Associate Prof. CHEN Longxiang’s team in Prof. WANG Fengxiang’s research group from Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences enhanced the air storage capacity of the A-CAES system.

The researchers introduced an innovative temperature regulation method for the A-CAES system. During the discharging process, the circulating water was utilized to recover the waste heat from the heat storage subsystem and air turbines. At the optimal moment, the heated water is injected under pressure into the air storage tank to raise the temperature. The spray technique is employed to enhance heat transfer. The increase in air temperature decreases its density, reducing the amount of residual air in the tank and improving the effective air storage density.

Furthermore, by injecting a specific volume of heated water, the space initially used for air storage is partially replaced by water, which increases the amount of air released. During the charging process, the water is discharged from the air storage tank, allowing a portion of the pump work to be recovered through a turbine. As a result, the effective air storage density in the tank can be further enhanced.

Based on the novel temperature regulation method, the modified system achieves a round-trip efficiency of 71.71%, comparable to the conventional A-CAES system of 71.41%. However, the effective air storage density of the modified system is 47.24 kg/m³, representing a 15.08% increase over the conventional A-CAES system of 41.05 kg/m³.

This study presents an innovative air temperature regulation method that offers a promising solution for enhancing the air storage performance of the A-CAES systems.

Schematic diagram of the A-CAES system based on temperature regulation.

Contact:

Associate Prof. CHEN Longxiang

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: chenlx@firsm.ac.cn