A review of underground energy storage: Modeling, experiments, and challenges

As the global demand for clean and reliable energy increases, technologies such as compressed air energy storage, underground gas storage, and geothermal energy storage have emerged as critical solutions to mitigate the intermittency and instability of renewable energy sources. These Underground Energy Storage (UES) systems are governed by complex interactions between thermal, hydraulic, and mechanical processes, which play a pivotal role in determining the safety, stability, and operational efficiency of UES systems. This paper presents a comprehensive review of UES to summarize recent research developments and challenges of multiphysics modeling and experiments across multiple spatial scales. The review examines the practical engineering applications of major UES technologies and provides an analysis of how the multiphysics phenomena and physico-mechanical properties of geological formations affect UES system performance from microscales to macroscales. The experimental work from lab-scale experiments and field-scale measurements is also summarized to highlight key considerations for designing and managing effective storage systems, mainly including system mechanical stability, gas tightness, and thermodynamic responses under different operational conditions. Lastly, this review underscores key challenges and outlines future research directions, with particular attention given to the role of chemical interactions in multiphysics coupling and the need for integrated, cross-scale modeling approaches to support the continued development of UES technologies.