Dynamic performance analysis of hydrogen production and hot standby dual-mode system via proton exchange membrane electrolyzer and phase change material-based heat storage

The production of hydrogen by proton exchange membrane water electrolyzers (PEMWEs) integrated with renewable energy sources is receiving significant interest for its environmental benefits. While, powered by intermittent renewable electricity, the frequent start-up/shut-down events put forward an urgent need for PEMWEs to have rapid start-up capabilities and will significantly accelerate the degradation of electrolyzer, increasing the failure risk and cutting down the cost-effectiveness. In this paper, a novel hydrogen production and hot standby dual-mode system aiming at fast start-up ability as well as slow degradation is proposed. Thermal energy storage based on phase change material (PCM) is used to manage the heat of the electrolyzer by recovering the heat produced during hydrogen production mode and utilizing it to maintain the electrolyzer temperature during hot standby mode. The operating strategy has been given and the dynamic performance has been analyzed. Results indicated that an electrolyzer with a capacity of 397.2 Nm3/h can cut start-up time by up to 785 s (from 1067 to 282 s). In the extreme situation, from 0 A to the rated current of 320 A, the start-up time of PEMWE is reduced from 118 s to 88 s, and the voltage overshoot is reduced by 23.91 % when compared to that of a cold start. Moreover, through waste heat recovery and utilization, the system efficiency can be improved. The system employing PCM with a higher melting point (64 °C) achieves an efficiency of 58.86 %, which is 1 % and 2.2 % greater than the systems using PCM melting at 45 °C and without heat storage, respectively.