Thermodynamic of a novel solar heat storage compressed carbon dioxide energy storage system

•A solar heat storage CCES system was proposed.•The thermodynamic model of the system was established.•The thermodynamic characteristics of the system were analyzed.•The sensitivity analysis of the system out was carried out. To improve the cycle efficiency of compressed carbon dioxide energy storage (CCES), a solar heat storage CCES system has been proposed. The thermodynamic model of system was built for the trough solar heat storage trans-critical CCES system and the trough solar heat storage super-critical CCES system, and the corresponding thermodynamic analyses are carried out. The consequences indicate that the cycle efficiencies of the two systems are 77.75% and 67.72%, which are respectively 30.18% and 25.87% higher than the trans-critical CCES system and super-critical CCES system. Moreover, the thermodynamic performance of the trough solar heat storage trans-critical CCES system is better than the trough solar heat storage super-critical CCES system except for the energy generated per unit volume of storage. Based on these results, it indicates that the system can effectively elevate the power storage efficiency and alleviate the impact of solar power generation on the grid by absorbing solar energy. In addition, the influences of the inlet temperature of the expander, energy storage pressure, energy release pressure and the outlet pressure of the final expander on the thermodynamic characteristics of the system are revealed.