Abstract: A high operating temperature is essential to activate the hydrogen storage reaction of Mg-Ni-Y alloys. In previous studies, heating the whole Mg-Ni-Y alloy bed to a high temperature through fluid or electrical elements is time- and energy-consuming, resulting in low operating efficiency and large energy consumption. This is particularly crucial for large-scale applications. In this study, a reaction-induced localized self-heating method is proposed to achieve fast and efficient hydrogen storage in modular Mg-Ni-Y alloy beds. A numerical model integrated with wide-temperature hydrogenation reaction kinetics is developed to simulate the entire hydrogenation process, including startup and reaction processes. The positive feedback relationship between temperature and reaction fraction is unveiled as the driving force for hydrogen storage startup. The startup duration and energy consumption of the alloy bed with localized self-heating are reduced by two orders of magnitude compared to those with conventional fluid heating. Meanwhile, the hydrogenation reaction duration is reduced by at least half. Parameter optimization indicated that through localized self-heating, a tiny initial heating power of 360 W enables starting the hydrogenation reaction in an alloy bed with 1 kg hydrogen capacity within 60 s. The proposed method weakens dependence on large energy supply for the hydrogenation process of Mg-based material bed, which contributes to the application and promotion of Mg-based hydrogen storage materials.

Key words: Magnesium alloy, Hydrogen storage, Hydrogenation reaction, Startup process, Self-heating