Simulation on a novel liquid hydrogen based energy storage system for meeting electricity demand via photovoltaic sources

This study presents and simulates a novel liquid-hydrogen-based solar energy system to meet electricity demand. The study includes liquid hydrogen (LH2) cold energy recovery and tank volume optimization, system simulation, and efficiency analysis. System simulation results demonstrate the proposed system can meet a daily load of 1095 MWh with a 950 m3 LH2 tank. The maximum exergy efficiency of LH2 cold energy recovery is 58% and tank volume optimization provides guidelines for tank selection. Efficiency analysis reveals the system total and storage round-trip efficiency (RTE) are 53.3% and 38.1%, respectively, primarily due to significant exergy losses in the electrolyzer (34.9%), hydrogen liquefaction (23%) and fuel cell (38%). A solar electricity system without energy storage (SSWOES) is introduced as a reference. Comparison results indicate the proposed system is more efficient when the ratio of solar power generation to user demand (RPv-User) exceeds 1.8. Further efficiency studies show that with slight technological improvements, the total and storage RTE can reach 62.72% and 48.27%, respectively. Moreover, the RTE of the proposed system has the potential to reach 86% in the future.