problem with hydrogen gas). Tanks made of carbon and glass fibres reinforcing plastic as fitted in Toyota Marai and Kenworth trucks are required to meet safety standards. Few materials are suitable for tanks as hydrogen being a small molecule tends to diffuse through many polymeric materials. The most common on board hydrogen storage in today's 2020 vehicles is hydrogen at pressure 700bar = 70MPa. The energy cost of compressing hydrogen to this pressure is significant. Pressurized gas pipelines are always made of steel and operate at much lower pressures than tube trailers. Liquid hydrogen Alternatively, higher volumetric energy density liquid hydrogen or slush hydrogen may be used. However, liquid hydrogen is cryogenic and boils at 20.268 K (–252.882 °C or –423.188 °F). Cryogenic storage cuts weight but requires large liquification energies. The liquefaction process, involving pressurizing and cooling steps, is energy intensive. The liquefied hydrogen has lower energy density by volume than gasoline by approximately a factor of four, because of the low density of liquid hydrogen – there is actually more hydrogen in a litre of gasoline (116 grams) than there is in a litre of pure liquid hydrogen (71 grams). Like any other liquid at cryogenic temperatures, the liquid hydrogen storage tanks must also be well insulated to minimize boil off. Japan has a liquid hydrogen (LH2) storage facility at a terminal in Kobe, and was expected to receive the first shipment of liquid hydrogen via LH2 carrier in 2020. Hydrogen is liquified by reducing its temperature to -253 °C, similar to liquified natural gas (LNG) which is stored at -162 °C. A potential efficiency loss of 12.79% can be achieved, or 4.26kWh/kg out of 33.3kWh/kg. Liquid organic hydrogen carriers (LOHC) Storage as hydride Distinct from storing molecular hydrogen, hydrogen can be stored as a chemical hydride or in some other hydrogen-containing compound. Hydrogen gas is reacted with some other materials to produce the hydrogen storage material, which can be transported relatively easily. At the point of use the hydrogen storage material can be made to decompose, yielding hydrogen gas. As well as the mass and volume density problems associated with molecular hydrogen storage, current barriers to practical storage schemes stem from the high pressure and temperature conditions needed for hydride formation and hydrogen release. For many potential systems hydriding and dehydriding kinetics and heat management are also issues that need to be overcome. A French company McPhy