Analysis of motion of super-massive air-damping solid gravity energy storage system under extreme working conditions

Solid Gravity Energy Storage (SGES) is a promising mechanical energy-storage technology suitable for large-scale applications. Ultra-large mass SGES systems can achieve energy storage on the order of gigawatt-hours (GWh). However, in extreme situations, such as earthquake or traction system failure, uncontrolled free-fall of the load can occur, posing the risk of unexpected energy release in a short period of time, potentially leading to severe secondary accidents. Ensuring the safe operation of SGES is of great significance. The existing literature lacks research or effective designs for the safe operation of SGES under uncontrolled conditions. In this study, a specific SGES design was proposed that, incorporates air damping to ensure the safe release of energy during the uncontrolled descent of the load. A quantitative study on the safe operation of SGES was conducted. This study first describes the design scheme and then establishes a numerical model based on computational fluid dynamics (CFD) and rigid-body dynamics coupling. Parameter analysis of the SGES was performed, demonstrating that the adoption of the air damping design scheme ensures the safety performance of ultra-large-mass SGES systems on the order of GWh during uncontrolled operations.