Three-dimensional multi-physics simulation and sensitivity analysis of cyclic energy storage in salt caverns

Large-scale storage technologies are crucial to balance consumption and intermittent production of renewable energy systems. One of these technologies can be developed by converting the excess energy into compressed air or hydrogen, i.e., compressed gas, and storing it in underground solution-mined salt caverns. Salt caverns are proven seals towards compressed air and hydrogen. However, several challenges, including fast injection/production cycles and operation of systems of caverns, are yet to be resolved to allow for a safe scale-up of energy storage in salt caverns. To address these challenges, it is important to identify key parameters that impact both the safety and efficiency of the operations. For this purpose, the present study conducts sensitivity analyses to show the importance of different parameters on the time-dependent mechanical behavior of salt caverns, individually and in a multi-cavern system. The impact of different deformation mechanisms (e.g. transient and reverse creep), model calibration, cavern shape, presence of interlayers and multi-cavern interactions are investigated in this study. The constitutive model adopted in this work and the mathematical formulation are presented in detail. Additionally, an open-source three-dimensional simulator, named “SafeInCave”, is developed for the numerical solution of the non-linear governing equations. The findings provide insights into improving the reliability of numerical simulations for the safe and efficient operation of salt caverns in energy storage applications. • A constitutive model for salt rock comprising transient, reverse, and steady-state creep is employed. • A detailed procedure for obtaining the consistent tangent matrix for the numerical formulation is presented. • Development of an open-source 3D finite element simulator for the mechanics of salt caverns. • The impact of salt rock model calibration in laboratory scale and cavern scale is analyzed. • Sensitivity analyses to different deformation mechanisms, presence of interlayers, cavern shapes and mutual interactions are performed.