@Jeffypooh, you are correct. Doesn't really change the outcome in terms of efficiency.
@aks. I know that. I'm also not saying that. I am only drawing a parallel between what the Hindenburg disaster did for airships and what would happen in a new hydrogen incident.
@sir alien, there is no such thing as low pressure storage for hydrogen if you want any sort of approximation of efficient energy density. Hydrogen for these purposes is stored at 200 barg or even more. Petrol (and diesel even more so) is surprisingly hard to ignite and even harder to get a proper explosion. Not so with hydrogen which will explode at a very wide mix ratio band, has an extremely low ignition energy threshold and can burn from even tiny leaks. On top of that the flame from a pure hydrogen leak is almost invisible and very very hot. Much hotter than a fuel explosion.
I have worked with the stuff and it really is not to be taken lightly. It is not even close to comparable to working with petrol of natural gas.