A review of thermal coupling system of fuel cell-metal hydride tank: Classification, control strategies, and prospect in distributed energy system

Hydrogen is of great importance to solve the energy crisis and environment pollution, and multiple hydrogen storage methods have been proposed, among which the metal hydrides (MHs) have attracted wide attentions in recent years. Considering the complementary heat demand of MH and fuel cell (FC) during operation, a thermal coupling system (TCS), where part of the heat generated by FC is transferred to MH tank to facilitate the endothermic hydrogen desorption, has been proposed and investigated in the literatures. However, since the heating of MH tank may retard the evolution of FC towards set operation point and decrease the system efficiency, a control strategy with rapid response and high precision is indispensable for the steady and efficient operation of TCS. This study reviews the research status and limitations of TCS classified according to the heat transfer mode, then the control strategies under various application scenarios are discussed and summarized. Furthermore, three crucial technical issues associated with the application of TCS in distributed energy system are highlighted for future investigations.