With the growing global demand for renewable energy, effectively storing and utilizing these intermittent energy sources has become a critical challenge. The adiabatic compressed air energy storage (A-CAES) system offers a viable solution for stabilizing renewable energy fluctuations. Improving its performance is essential for enabling the widespread adoption of renewable energy.

The constant volume air storage method is widely used in traditional A-CAES systems. However, it has a significant drawback: low air storage density, particularly when artificial tanks are utilized. This limitation leads to an increased number of tanks, which in turn raises capital costs.

In a study published in Renewable and Sustainable Energy Reviews, researchers from the Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences enhanced the air storage capacity of A-CAES systems.

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

Furthermore, by injecting a specific volume of heated water into the tank, part of the air storage space was replaced by water. This change increased the amount of air that could be released. During the charging process, the water was 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 was enhanced.

Based on the novel temperature regulation method, the modified system achieved 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 was 47.24 kg/m³, representing a 15.08% increase over the conventional A-CAES system of 41.05 kg/m³.

This study provided a promising solution to enhance the air storage performance of A-CAES systems.