What's the actual point of doing this? This is another sneaky fossil fuel "idea" that just wants to make sure their product is still required in the electrified future. Hydrogen isn't an energy source, it's a storage medium. It compares poorly to batteries is a variety of use cases, fuel cells can be a consumable component, and you have to deal with storing the hydrogen before you convert it to electricity or burn it (have fun assembling all of those parts for a combustion engine).

I get it - it's cool science and there's probably a couple of edge cases or whatever where this does make sense, but solar panels, batteries, and electric motors are all here and mostly work. The technology for all of that will continue to get better and make any hydrogen use cases even less practical. Just leave the oil in the ground.