Hydrogen is not particularly good for aviation: it either requires a lot of cooling, or a really high pressure, and/or leaks through solid containers, or has really poor energy density.
It’s a decent intermediary high energy density storage on the ground, where excess renevables can run through a fuel cell and produce hydrogen that can be stored at high pressures and low temperatures in bunker-like containers. Those don’t tend to fly very well though, at most swim somewhat decently to deliver the hydrogen wherever its needed.
Hydrogen can be used in rockets though, because of the great oxyhydrogen reaction’s efficiency, but you’ll notice they tend to leak like crazy… which, once more, is highly undesirable for aviation.
OGM. No, the thing you can see is condensation from the atmosphere. You can’t see an hydrogen leak in any reasonable environment.
Guess what? Leaking is a long term problem, and not very relevant if you refuel just before your trip. Its balance for airplanes is all dictated by the needs of a high-pressure storage against the unbeatable energy density. Up to now, hydrogen has always lost, and will probably keep losing for most airplanes, but commercial aviation is constantly pushing over factors that change the equilibrium towards it.
It isn’t a problem if you fill up a container with liquid hydrogen right before your trip, the trip lasts less than an hour, then you discard the container and let it burn up on reentry.
It is a problem though, if you intend to fill up the same container multiple times, keep hydrogen in it for hundreds of hours, and subject it to vibrations.
Another problem is that even in its liquid state, while the energy density to weight ratio is great, its energy density per volume is pitiful:
Meaning, a plane could carry the same energy in 3 times less weight of fuel, which is great, but still need 8 times larger deposits to do it, which would mess up the aerodynamics… and would still have a high chance of springing a leak.
It’s no coincidence that SpaceX is using liquid methane for its reusable rockets.
Hydrogen is not particularly good for aviation: it either requires a lot of cooling, or a really high pressure, and/or leaks through solid containers, or has really poor energy density.
It’s a decent intermediary high energy density storage on the ground, where excess renevables can run through a fuel cell and produce hydrogen that can be stored at high pressures and low temperatures in bunker-like containers. Those don’t tend to fly very well though, at most swim somewhat decently to deliver the hydrogen wherever its needed.
Hydrogen can be used in rockets though, because of the great oxyhydrogen reaction’s efficiency, but you’ll notice they tend to leak like crazy… which, once more, is highly undesirable for aviation.
OGM. No, the thing you can see is condensation from the atmosphere. You can’t see an hydrogen leak in any reasonable environment.
Guess what? Leaking is a long term problem, and not very relevant if you refuel just before your trip. Its balance for airplanes is all dictated by the needs of a high-pressure storage against the unbeatable energy density. Up to now, hydrogen has always lost, and will probably keep losing for most airplanes, but commercial aviation is constantly pushing over factors that change the equilibrium towards it.
Condensation is one thing, hydrogen leaking straight through the metal is another.
https://en.m.wikipedia.org/wiki/Hydrogen_embrittlement
It isn’t a problem if you fill up a container with liquid hydrogen right before your trip, the trip lasts less than an hour, then you discard the container and let it burn up on reentry.
It is a problem though, if you intend to fill up the same container multiple times, keep hydrogen in it for hundreds of hours, and subject it to vibrations.
Another problem is that even in its liquid state, while the energy density to weight ratio is great, its energy density per volume is pitiful:
Meaning, a plane could carry the same energy in 3 times less weight of fuel, which is great, but still need 8 times larger deposits to do it, which would mess up the aerodynamics… and would still have a high chance of springing a leak.
It’s no coincidence that SpaceX is using liquid methane for its reusable rockets.