A landscape of hydride compounds for off-board refilling of transport vehicles

The authors compare the energy consumption of hydrogen cars (using fuel cells) with electric cars (using batteries) and conventional petrol cars finding that hydrogen cars are preferable to electric cars for long distances. They evaluate several types of hydrogen storage materials in terms of off-board refilling, in which hydrogen uptake takes place outside the vehicle. Literature values for enthalpy and entropy of formation etc. are used to calculate hydrogen densities, heat production and theoretical desorption temperature. Additionally, experimental literature values for temperature and pressure of (de)hydrogenation, kinetics and cycling stability are summarized. The results are discussed assuming that hydrogen refilling takes place in a replaceable tank outside the vehicle, which reduces the DOE requirements to high volumetric and gravimetric density, moderate release temperature, sufficiently fast release and high reversibility. They are fulfilled by materials like NaAlH4, while even better performance can be expected from compounds like LiBH4+MeHx or Mg-Ti composites