Thermodynamic performance analysis and simulation of a new type of compression CO2 energy storage system in salt caverns

In recent years, renewable energy sources like wind and photovoltaic power have grown rapidly due to their sustainability. However, their random, intermittent nature often leads to energy wastage. Hence, a new energy storage system for storing compressed CO2 through salt caverns was constructed in this study. The system is based on phase transitions and thermodynamic processes in fluid physics, utilizing gas–liquid phase conversion and two-state synergistic energy storage technology. In order to test the performance of the new system, thermodynamic theoretical models and simulation models of the new energy storage system were established. The thermodynamic theoretical model investigates the thermodynamic performance and economic index of the new system. The thermodynamic parameters of the new system at each cyclic state point were calculated by embedding the partial results obtained from the theoretical model in MATLAB. The results show that the theoretical model calculates a system with an energy storage efficiency of 66.8% and an average energy cost of only 9.03 US cents/kW h. Combined with the results of MATLAB calculations, a thermodynamic simulation model of the new system was developed using Ebsilon to analyze the changes in enthalpy, entropy, temperature, and pressure throughout the energy storage process. The results show that the operating efficiency of the simulation model is 68.7%, and the deviation from the MATLAB calculation is less than 2%, which realizes the organic combination of the theoretical model and the simulation model, and not only shows the superiority of the performance of the new system, but also confirms the rationality of the new system. This work highlights the role of fluid physics in the design and optimization of energy storage systems, providing valuable insights for integrated energy system development and new energy storage applications.