Performance Analysis of Isobaric Compressed CO₂ Energy Storage System with Pumping Compensation

Compared with the compressed air energy storage system, energy storage system with CO₂ as working fluid has the advantages of high energy storage density and compactness. In this paper, a novel isobaric compressed CO₂ energy storage system with a flexible gas holder is proposed. The thermodynamic modeling of the compressed CO₂ energy storage system is established and the impact of some key parameters on system performance is studied. The results show that round-trip efficiency gradually increases from 67.86% to 77.00% as the compressor isentropic efficiency rises from 75% to 95%. As the relative pressure loss rate of the heat exchanger increases from 0.25% to 4.5%, the system round-trip efficiency experiences a decline from 73.12% to 71.49%.