Metal hydrides are a promising class of storage materials, many of which are comprised of low-cost, earth-abundant elements with high volumetric hydrogen capacity. Historically, assessments of the viability of a metal hydride for hydrogen storage relied on gravimetric and volumetric capacities based on the material's elemental composition, reaction pathway, and crystallographic density. This incorrectly assumes that intrinsic material properties are always directly correlated with storage system performance-in particular usable capacity and H2 desorption rate-and that these are independent of system design. In fact, conversion to a systems-level storage capacity is required for direct comparison with the DOE targets (equating storage capacity on a material basis with the DOE system capacity targets has sometimes been a source of confusion in the literature). Accurate assessment of the usable capacity of a materials-based storage system must account for the weight and volume of the tank and ancillary balance of plant (piping, valves, etc.), which makes the operational capacity substantially less than the theoretical capacity of the storage materials. Another common assumption concerning material-based storage is that hydrogen can be fully desorbed from the material in the tank, i.e. the reversible capacity on a material basis can be fully utilized within a tank design. This neglects the fact that heat transport through the metal hydride bed can be ratelimiting owing to the generally low metal hydride thermal conductivities (k). For example, the value for NaAlH4 is ~0.5 W m -1 K -1 under 1 atm H2 whereas that for graphite is 2000 W m -1 K -1 and graphene has values between 1500 and 5000 W m -1 K -1 at 25 C. Consequently, without an engineering or material strategy to enhance heat transport through a hydride-filled storage tank, it may not be possible to desorb