Do you really think zero emission air transport is outside the realms of possibility? The worlds first Hydrogen plane flew in the UK last year.
The hard part is not the technical challenge of building a hydrogen airliner.
The hard part is building a hydrogen airliner that is in any way commercially useful.
It will look like a fuel tank with a passenger cabin grafted on, not like any extant airliner.
It probably won't fit most of the extant airport infrastructure and fueling it will be a nightmare.
It will have all the problems of the A380, only more.
The Skylon spaceplane has a projected launch mass 56% of the A380s takeoff weight, and
yet the fuel tank results in this, with something like treble the fuel volume - and the vast majority of the fuel mass is actually high density LOX instead of LH2, but the vast majority of the tank volume is for LH2.
Electric planes are getting ready for commercial service in Seattle. Yes, short distance for now. But that’s how EVs started.
Unfortunately, electric cars are not constrained by the laws of physics to save every gram.
The batteries required to provide aircraft with useful payload masses and useful ranges
simply do not exist at present.
Nevermind the safety requirements for type classification for long distance flights over oceans.
Remember this is an industry that, in the US, is still burning leaded petrol in general aviation applications because the FAA refuses to allow any oxygenates on the plane!
No ethanol, methanol or MTBE to boost octane rating.
If effective zero carbon aviation is to arrive in the next 25 years, it will be using zero carbon synthetic kerosene.