Performance analysis and multi-objective optimization of a combined system of Brayton cycle and compression energy storage based on supercritical carbon dioxide

The energy storage system plays a pivotal role in optimizing the power grid's peak mobilization. In this study, we propose a combined cycle of supercritical carbon dioxide (sCO₂) recompression cycle (sCO₂-RC) coupled with compressed sCO₂ energy storage (S-CCES) system. Two distinct layouts are thoroughly investigated, each corresponding to different auxiliary heat source locations: utilizing waste heat to heat hot water of S-CCES (SCW-CCES) and heat CO₂ of S-CCES (SCC-CCES). Through comprehensive thermodynamic modeling and analysis, we evaluate the performance of both layouts and conduct multi-objective optimization using a genetic algorithm. The results indicate that, under identical design conditions, the heat input leads to a respective increase of 4.25 MW and 7.02 MW in the output power of S-CCES for the SCW-CCES and SCC-CCES layouts. Furthermore, parametric analysis reveals that the performance of SCC-CCES surpasses that of SCW-CCES when considering performance indicators other than round-trip efficiency (RTE). The results obtained from multi-objective optimization demonstrate that the optimal solution for SCW-CCES achieves a higher RTE of 25.94 %, while the optimal solution for SCC-CCES exhibits a superior levelized cost of electricity and exergy efficiency, amounting to 68.94 $/MWh and 58.76 %, respectively.