The price of production is only a small part of the overall cost of hydrogen — the gas also needs to be stored and transported, which sounds simple, but is anything but.

Hydrogen (H2) is the smallest molecule that exists, measuring 0.000000074mm wide — 100 times smaller than a methane molecule, meaning that it is very hard to store. It will slowly leak through some materials, cracks or poor joints and can make metal brittle.

And being the least dense gas in the universe — it is 11 times lighter than air — means that in its natural state, a storage space of 11 square metres would be required to store just 1kg of hydrogen (enough for a hydrogen-powered car to drive about 100km).