H2

[vyv_cox]

To store a useful amount, even a small amount for a short while, it will need compressing or liquefying. They are both energy intensive and the kit to do it is £££££££££.

Hydrogen molecules are so small that they can leak through seals and gaskets that would hold methane and other hydrocarbon gases. In refineries normal split-line compressor casings cannot be used with hydrogen: barrel casings are used instead. Piping needs to be specially designed. Naturally, as you say, the technology needed is not cheap.