Comment Re:White elephant (Score 1) 63
Liquid hydrogen has around 120 MJ/kg versus 43 for jet fuel. Liquid hydrogen has 8.5 MJ/l to jet fuel's 35. Funny, about 3:1 for both, just in reverse directions.
Weight is more important when you're trying to take off.
A cryogenic cooled and massively insulated tank will not be light weight!
It will also be considerably larger in volume, perhaps triple the volume required for kerosene. Where will that volume go?
Personally, I don't know I'm comfortable flying a plane with a cryogenic fuel. Talk about wing icing!
It's only cold at standard atmospheric pressure.
I assume the trade-off between temperature/pressure is one of the things they'll be researching, along with insulation to keep the wings ice-free.
In the case of a crash I think that being frozen by hydrogen will hurt less than being burnt by kerosene, so... that's a win!
Adding insulation to keep it cool will add weight and volume. And as pressure goes up, so does the mass required to maintain structural integrity.
Not sure being frozen to death by liquid hydrogen would be very pleasant either. But then, if you've already crashed to the point of rupturing fuel tanks, chances are you're pretty mangled already, so it's probably a moot point.
All in all, I'd be surprised if H2 powered planes are at all viable, or competitive with synthetic fuel that might be manufactured using excess renewable resources.
With $107b in investment, you could massively over provision the wind and solar power you need, so that any excess could be used for synfuel production, and planes can use that synfuel with existing technology and infrastructure.