两种新型等压液态二氧化碳储能系统与抽水蓄能耦合的热经济性能分析

Abstract Liquid carbon dioxide energy storage is a promising technology for stabilizing renewable power output; however, the inefficiency and diseconomy caused by non-isobaric storage are generally overlooked. In response, this study proposes two novel isobaric liquid carbon dioxide energy storage systems coupled with pumped hydro storage , the pumped hydro storage-assisted and high backpressure pumped hydro storage-assisted systems. These systems achieve isobaric storage by incorporating hydraulically designed carbon dioxide-water co-storage tanks. The study begins with a dynamic behavior analysis of the basic system, followed by a thermo-economic performance comparison, parametric analysis, and an economic uncertainty analysis based on multi-objective optimization. Results show that neglecting non-isobaric storage in the basic system leads to a 26.44 % discrepancy in total exergy efficiency , a 59.67 % relative deviation in energy storage density and an economic overestimation. By avoiding unsteady-state operation, the high backpressure pumped hydro storage-assisted system outperforms the other two, achieving a total exergy efficiency, levelized cost of storage and net present value of 52.95 %, 0.131 $/kWh and 32.24 M$, respectively, while the pumped hydro storage-assisted system achieves the highest energy storage density at 3.85 kWh/m 3 . To further enhance thermo-economic performance, attention can be paid to key components such as compressor, turbine, condenser and tanks. Additionally, the high backpressure pumped hydro storage-assisted system exhibits the most favorable and stable economic performance, with a levelized cost of storage of 0.154 ± 0.022 $/kWh and a net present value of 22.11 ± 9.05 M$. The system economic viability can be further improved by expanding discharge capacity and operating durations, particularly in regions with favorable electricity price structures.