Thermo-economic and advanced exergy analysis of a novel liquid carbon dioxide energy storage system coupled with solar energy and liquefied natural gas

Nowadays, proportion of renewable energy in the current energy structure has gradually increased, driving energy storage systems to play an increasingly important role in energy market. In this study, a novel liquid carbon dioxide energy storage system coupling solar energy and liquefied natural gas with low-pressure storage is proposed. Thermodynamic model of the system was established, parameter analysis and advanced exergy analysis was conducted. The results show that coupling solar energy enhanced round-trip efficiency, storage density and levelized cost of electricity by 30.55 %, 30.55 % and 17.91 %, respectively, compared to the system without solar energy. Advanced exergy analysis indicates that the interconnection between system components is not very strong. Both traditional and advanced exergy analyses indicate that heat exchangers should be prioritized for optimization, and coupling solar energy significantly alters the optimization sequence of certain components. Through the comparison of the two methods, it is evident that while the optimization priority of condenser did not undergo a significant shift, its exergy destruction decreased from several orders of magnitude higher than other components to a similar scale. Compared to traditional exergy analysis, advanced exergy analysis demonstrated significant differences in the optimization priorities of various components.