Numerical and experimental investigations of concrete lined compressed air energy storage system

Compressed air energy storage (CAES) is considered one of the critical technological approaches to bridging the gaps between clean electricity production and electricity demand. An in-situ air storage test in a shallow buried underground cavern was introduced to understand better the connection and mutual influence between aerothermodynamics and cavern safety stability in various aspects of CAES. Moreover, a corresponding finite element model of the multilayer cavity structure considering the multi-field coupling effect and rebar embedding was developed to verify the experimental results. The experimentally measured temperature, air pressure, displacement, and stress are in good agreement with the calculated results, showing the success of the modeling in this paper. The cavern temperature shows large fluctuations for the whole storage phase. The maximum temperature of the air and the cavern walls are 53 °C and 46 °C, respectively. After water circulation heat exchange, the temperature can be regulated within a reasonable range (<40 °C). The cavity walls can reverse the heat output of the air through heat exchange during the discharging phase resulting in a slower temperature drop. The concrete stress is about 1/10 of the reinforcement stress, showing that the deformation between the rebar and concrete is coordinated, and both are in the elastic deformation stage. The sealing layer, reinforced concrete lining, and rock surrounding share the internal air pressure, accounting for 2.07%, 27.55%, and 70.38%, respectively. The surrounding rock is the most important part of bearing the internal pressure, and it is an essential means to improve the safety of the cavity by carrying out anchoring and grouting of the surrounding rock. The thermodynamic processes and stress response are affected by the convection heat transfer coefficient, thermal conductivity, charging time, and leakage rate.