A new theoretical model of thermo-gas-mechanical (TGM) coupling field for underground multi-layered cavern of compressed air energy storage

Compressed air energy storage (CAES) is a promising method of large-scale energy storage. As the key components of the CAES, the underground cavern filled with compared air of the high-temperature and high-pressure would generate larger temperature, air seepage and stress fields to influence the safety of the CAES. Currently, coupling fields of CAES cavern are studied mainly by numerical method and little by theoretical method. The theoretical calculations of CAES cavern are almost by thermo-mechanical coupling model, where the air pressure is taken as a static pressure regardless of the gas seepage field. In this paper, a new theoretical model of thermo-gas-mechanical (TGM) coupling field with consideration of the gas seepage is established. Research results show the analytic solutions of the temperature, gas seepage and stress fields for single-, double- and three-layered caverns have almost the same changing trends with time but different with radius. The three-layered cavern has smaller heat/gas loss and better stability than the single- and double-layered cavern and therefore becomes a promising structure form. The new TGM coupling model is verified by the good agreement of our analytical solutions with available numerical results, and can provide theoretical basis for the safety assessment of the CAES multi-layered cavern. • A theoretical model of TGM coupling field is built for multi-layered CAES cavern. • The new TGM coupling field model takes the effect of gas seepage into account. • TGM coupling fields of the multi-layered CAES caverns are theoretically analyzed. • Theoretical results of the CAES cavern are in good agreement with numerical results. • The three-layered cavern has better stability than the single/double-layered cavern.