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The first hydrogen-powered planes are taking flight
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Is hydrogen more energy dense than other net zero fuels such as methenol?
It depends on whether you mean by weight or by volume.
By weight, hydrogen has an almost unbeatable energy density. It's much higher than methanol or even gasoline.
By volume, hydrogen has a horrible energy density, several orders of magnitude lower than any modern type of battery, for example.
So if you have infinite space, hydrogen is great. But a plane does not have infinite space. So you try to compress the hydrogen or cool it down to increase the energy density. However, this will still come out at much worse than gasoline or jet fuel.
The big issue for aircraft is weight more so than volume. You can add a section and stretch an airplane without too much issue. Whereas the ability to lift is limited by weight and engine power.
Weight is definitely the most important issue for a plane, but at some point volume also becomes a limiting factor. Yes, you can stretch an airplane, but that also makes it heavier. With jet fuel, they're currently using every available space, storing most of it in the wings and some also in the fuselage. That's much harder to do with hydrogen, because the pressure containers can't just take on any shape. They have to withstand absolutely insane pressures, so they have to be either cylindrical or spherical.