Energy, exergy, economic and exergoeconomic (4E) analysis of a high-temperature liquid CO2 energy storage system: Dual-stage thermal energy storage for performance enhancement

Liquid carbon dioxide energy storage (LCES) system can improve the renewable energy penetration in the grid, but the mismatch between the compression heat and thermal energy storage (TES) system causes considerable irreversible losses. In this paper, a novel high-temperature (300–400 °C) LCES system with a dual-stage TES loop is introduced to enhance the heat transfer and energy storage performance. The proposed high-temperature LCES system is analyzed from the perspectives of energy, exergy, economics and exergoeconomics. Under design conditions, the round-trip efficiency, energy storage density, and levelized cost of electricity of the improved LCES system are 66.68 %, 28.57 kWh·m−3, and 0.1315$·kWh−1, respectively. The dual-stage TES loop improves the heat recovery factor and round-trip efficiency by 19.10 % and 14.59 % compared to the basic LCES system. The parametric analysis indicates that the system performance initially improves and then declines as the operating temperature of the low-temperature TES loop increases. The multi-objective optimization results show that the round-trip efficiency and energy storage density of the proposed high-temperature LCES system are at least 7.43 % and 62.49 % higher than those of low-temperature LCES systems.