Hydrogen storage in a two-liter adsorbent prototype tank for fuel cell driven vehicles

A two-liter prototype hydrogen adsorbent tank, filled with MOF-5 material, was built, tested and modeled as part of the work carried out within the U.S. Department of Energy Hydrogen Storage Engineering Center of Excellence. The hydrogen was stored adopting the flow-through cooling concept. This approach exploits the characteristics of low temperature recirculating hydrogen to provide the cooling power required to adsorb the gas. The heating power, required to discharge hydrogen, was provided adopting a honeycomb finned heat transfer system, powered with a resistive heater. The system demonstrated the ability to achieve excess adsorption capacities on the order of 6.5 wt% at 77 K and at pressures between 40 bar and 80 bar. Adopting the flow-through cooling charging approach, gravimetric and volumetric capacities of 12 wt% and 31 g/L (on a material basis) were achieved, respectively, in approximately 10 min, at temperatures of about 90 K and pressures of 80 bar. The hydrogen discharging tests were carried out at pressures between 80 bar and 2.5 bar with a single resistive rod operating at an electric power on the order of 40 W. The prototype system demonstrated the ability to drive continuously a fuel cell of approximately 1 kW (corresponding to the prototype scale), at its nominal power for about 1 h 10 min.