Development and assessment of a novel isobaric compressed hydrogen energy storage system integrated with pumped hydro storage and high-pressure proton exchange membrane water electrolyzer

Abstract

In the work, a novel isobaric compressed hydrogen energy storage system integrated with pumped hydro storage and high-pressure proton exchange membrane water electrolyzer is proposed to improve system performance. By integrating pumped hydro storage, the gas storage chamber can operate with a constant pressure at a counter-hydraulic pressure, enhancing the effectiveness and energy storage density of the system. Utilizing high-pressure proton exchange membrane water electrolyzer technology directly to produce high pressure hydrogen and oxygen simplifies the system structure by eliminating the need for gas compressors and cooling unit, thereby improving system stability. Additionally, insulated storage reservoirs are employed in the proposed system to store working fluids, maximizing system performance by minimizing potential waste heat losses. Furthermore, the electrical, thermal, and exergy efficiencies, as well as energy storage density of the proposed system, are assessed using thermodynamic techniques. The results indicate that the round-trip electrical efficiency, round-trip thermal efficiency, round-trip exergy efficiency, and energy storage density of the system can reach 35.39%, 81.03%, 37.89% and 53.46 kWh/m3, respectively. Lastly, parametric studies are conducted to further evaluate system performance under various working conditions.