Salute!
The biggest problem is the "green" production of the hydrogen.
Can't be electrolysis for awhile, as Europe/UK already having problems by shutting the nukes and trying to get windmills and PV farms to provide the volts/amps. The other common means for getting the H2 involves using evil greenhouse gases.
I also noted too many references directly or implied about the COP or other outfits trying to save the planet by reducing use of fossil fuels before reliable and plentiful and cheap "green" capabilities exist.
Gums sends...