Thermodynamic Analysis of a Carnot Battery Integrated with Coal-Fired Power Plant

High penetration of renewable power requires coal-fired power plants (CFPP) to enhance their operational flexibility effectively. In this study, a novel integrated system of a Carnot battery thermally assisted by the extraction steam from CFPP is proposed. The model of the integrated system is constructed, and the mechanism of improvement for the system is clarified through thermodynamic analysis. The results show that the equivalent round-trip efficiency and minimum output power change of the integrated system can reach 66.68% and 76.03 MW, respectively, and increasing the mass flow rate of extracted steam can decrease the output power of the CFPP to 0 MW. Energy flow analysis shows the improved efficiency of the charging and discharging process of the integrated system is the main factor in the improvement of the equivalent round-trip efficiency. Moreover, the improvement of the power generation efficiency of the CFPP during the discharge periods leads to an additional 2.17 MW of power generation from coal.