基于浅层海水的低压二氧化碳储能系统的热力学分析与经济性评价

Abstract Current carbon dioxide energy storage systems typically operate at extremely high supercritical or transcritical pressure levels, which significantly increases the implementation difficulty and cost, making it unfavorable for promotion and application. Therefore, to improve the application potential, this paper proposes an efficient low-pressure gas–liquid carbon dioxide energy storage system that utilizes shallow seawater as a heat source. A thermodynamic and economic model is established based on the system to analyze the impact of key parameters on system performance and evaluate its economic feasibility in multiple regions across China. The results show that the cold source temperature has minimal impact on the round-trip efficiency, while increasing the cold source temperature can enhance the energy storage density and exergy efficiency. In contrast, raising the cold storage temperature leads to a decrease in round-trip efficiency, exergy efficiency, and energy storage density. Specifically, when the cold source temperature is −30 ℃ and the cold storage temperature is set at 1℃, the system cycle efficiency, effective energy efficiency, and energy storage density can reach the optimal level, which are 72.38 %, 61.74 % and 0.093 kW·h/m 3 , respectively. In addition, simulations on three cases, Shenzhen, Nantong, and Qingdao, show that the levelized costs of storage in Shenzhen, Nantong, and Qingdao are 0.1146, 0.1251, and 0.1373 $/kWh, with investment payback periods of 8.6, 7.6, and 11.9 years, and final net present values of $8.9 million, $11.5 million, and $2.2 million, respectively. This demonstrates that the proposed system has good application prospects in coastal cities of different sea areas.