Energy geo-storage - analysis and geomechanical implications

The increasing energy demand, the mismatch between generation and load, and the growing use of renewable energy accentuate the need for energy storage. In this context, energy geo-storage provides various alternatives, the use of which depends on the quality of surplus energy. In terms of power and energy capacity, large mechanical energy storage systems such as Compressed Air Energy Storage (CAES) and Pumped Hydro Storage (PHS) are cost-effective and suitable for centralized power generation. In contrast, sensible and latent heat storage are appropriate for distributed applications when excess heat is involved. Energy density estimations highlight the advantages of compressed air over elevated water, and latent heat over sensible heat storage. From a geotechnical standpoint, the operation of geo-storage systems exerts complex effective stress, temperature, wet-dry, and freeze-thaw cycles. Although these excitations may not cause monotonic failure, they lead to ratcheting or shakedown behavior, both of which must be carefully analyzed to ensure the proper long-term cyclic response of energy geo-storage systems.