@dabertime @cstross

As in burning hydrogen in a combustion engine? There have been some good articles on Toyota's (naturally) hydrogen burning race car that sounds good until you realize that the fuel pump needed to be replaced multiple times during a race as the sealing rings degraded so fast from contact with the cryogenic liquid H2. The "Engineering Explained" YT channel did a good deep dive on it and noped pretty hard though gave props to Toyota for giving it a try.

Also H2 fuel cell does, kinda, work but having read the Toyota Mirai manual and seen the explicit list of the weird noises the car can make due to all the pumps, valves and relays and other moving parts in the drive train, that the car bricks itself once the H2 Tanks reach their 15 (10?) year lifespan unless dealer replaced and that certain atmospheric pollutants like sulphur dioxide can poison the fuel cell and I'm wondering how viable these things can ever be. And that's ignoring H2 sourcing and infrastructure