Just a note, it wasn't the hydrogen that torched the Hindenburg. It was the rocket fuel based dope that coated the fabric skins that blew up. Hydrogen has so little density that at standard temperature and pressure it expands and lifts faster than it can burn. Its of little threat to igniting its surroundings once the container is ruptured. The real issue with hydrogen airplanes is that you either need very heavy cryo tanks or really big, draggy ambient temp tanks. There is also the huge amount of electricity needed to get liquid hydrogen which usually comes from coal and oil power plants.

The big weakness of most non hydrocarbon based fuels is that they require more power to get into a usuable form than their hydrocarbon cousins. Until we build more nuclear, solar, and wind power facilities, we are still slaves to oil and coal.