MrJoyless t1_iy8xhwa wrote

>Hydrogen is more energy dense per pound,

True, but not by volume. That's why you see hydrogen tanks for rocket launches taking up a huge % of the total launch vehicle volume vs the oxidizer. Also the extra insulation required really offsets hydrogen's main weight saving benefit.

I'm not sure if there really is a good or safe way to transport or store hydrogen for air travel. Thermal issues would abound, especially with the temperature differentials airplanes experience at cruising altitude. That's not even mentioning the storage issues that occur since hydrogen is so damn small it can leak through seemingly solid containment vessels.