Here is a good article on some real world hydrogen uses.
https://www.bbc.com/future/article/2...onise-shipping
In a previous life I was an oxygen generator technician on submarines. Oxygen was made by using electrolysis to split the water into O2 and Hydrogen. It takes a large amount of electrical power to do this. Our units required 1050 amps at 480 volts. To upscale hydrogen production to meet current transportation needs is going to require 3 to 4 times more electrical generation capability than we have today.
Cryogenic storage is also going to require a percentage of the hydrogen production for generating electricity to continuously operate the storage plant.
The other part is the requirement that the water must be distilled prior to it being supplied to the electrolysis process.
In any large scale application these are real costs that must be borne. There is also the disposal of the impurities that are removed from the water. Again another toxic waste issue.