Hydrogen has been in use for several years already – especially in the industrial sector, in oil refining, and in the production of fertilizers and ammonia. It’s also used in the food industry to make the so-called “hydrogenated fats” present in several food items.
Nowadays, most of the demand for hydrogen is produced in the same place where it’s consumed (like oil refineries, for example, which make it for their own consumption), so there isn’t an actual market for it because hydrogen is not exchanged between different operators.