Performance analysis of coal-fired power plant with carbon capture integrated with a supercritical compressed carbon dioxide energy storage system

The application of large-scale energy storage technology is an effective approach to enhancing the flexible regulation capability of power systems. Supercritical compressed carbon dioxide energy storage (SC-CCES) technology is among the most promising methods for large-scale energy storage. This paper proposes a coupled system integrating SC-CCES with carbon capture coal-fired units. The system utilizes the S-CO2 from carbon capture coal-fired units as the working medium for the SC-CCES system, eliminating the need for a low-pressure gas storage chamber in the SC-CCES system. A thermodynamic model of the coupled system is developed, and its thermal characteristics are analyzed using a peak shaving scheme. The results indicate that the SC-CCES system enhances both the peaking flexibility and peaking depth of the coupled system compared to the carbon capture coal-fired unit alone. In pure storage mode, the coupled system can save up to 52.1 g/kWh of coal consumption during a peak shaving cycle, achieving a round-trip efficiency of 70.1 % and an energy density of 10.87 kWh/m3. When operating in electricity storage with heat storage mode, the SC-CCES system uses the reheated steam from the coal-fired unit to heat S-CO2, resulting in an energy storage efficiency of 45.49 %, an energy density of 23.1 kWh/m3, and a required high-pressure gas storage chamber volume of 851.4 m3/h. This study offers significant insights for the development of CO2-based energy storage technologies and supports the goals of ' carbon neutrality and peak carbon emissions reduction'.