Analysis of information sources in references of the Wikipedia article "Hydrogen storage" in English language version.
The situation is much worse than this, however, because before the hydrogen can be transported anywhere, it needs to be either compressed or liquefied. To liquefy it, it must be refrigerated down to a temperature of −253 °C (20 degrees above absolute zero). At these temperatures, fundamental laws of thermodynamics make refrigerators extremely inefficient. As a result, about 40 percent of the energy in the hydrogen must be spent to liquefy it. This reduces the actual net energy content of our product fuel to 792 kcal. In addition, because it is a cryogenic liquid, still more energy could be expected to be lost as the hydrogen boils away as it is warmed by heat leaking in from the outside environment during transport and storage.