Performance of a Thermally Coupled Hydrogen Storage and Fuel Cell System Under Different Operation Conditions

The performance of a hydrogen storage prototype loaded with AB5H6 hydride, whose equilibrium pressure makes it suitable for both feeding a H2/air proton exchange membrane (PEM) fuel cell and being charged directly from a low-pressure water electrolyzer, interacting thermally with the fuel cell exhaust air, is reported. The nominal 70 L hydrogen storage capacity of the prototype suffices for hydrogen delivery at 0.5 L min−1, which allows a power supply of 50 W for 140 min from the H2/air fuel cell in the absence of thermal interaction. The storage prototype was characterized by monitoring the internal pressure and the temperatures of the external wall and at the center inside the container at different hydrogen discharge conditions. The responses of the integrated system after either immersing the metal hydride container in air or exposing it to the fuel cell hot exhaust air stream under forced convection were compared. The system shows the best performance when the heat generated at the fuel cell is used to increase the metal hydride container temperature, allowing the operation of the fuel cell at 280 W for 16 min at a high hydrogen flow rate of 4 L min−1.