Regarding the planes, the Soviets had a plane working with hydrogen (and methane I believe). It's not particularly impossible, and at least much more doable than using batteries (for commercial jets).
The flying wing is a design improving the efficiency know for a long time (Airbus guys teaching us about it during my studies 15 years ago), but creates additional difficulties, on top of which the impossibility to evacuate the plane fast enough. You would have the same benefits whether your plane is using hydrogen or kerosene.
I still do not see planes using hydrogen. Just doing the math on how much electricity would be needed makes it really unlikely.
In the 70s engineers in CEA in France modified some cars on the campus to run on liquid hydrogen. Apparently burning hydrogen in a combustion engine is pretty straightforward. I think that's the plan about future H2 planes, make them use turbofans slightly modify to burn H2 instead of kerosen.
However the big problem is storing H2 onboard. Most of the fuel is in the wings, and very cold liquid hydrogen (icing) as well as very heavy high-pressure tanks won't fit there. That's why I mentioned that an entirely new concept may be necessary to make room for the fuel tanks inside the fuselage.
Yes, that's the problem. You embark much less energy as fuel, lose lots of room for passengers and cargo; I very much doubt this could make sense economically. My brother-in-law who is an aeronautical engineer at Airbus isn't convinced, either.
The flying wing is a design improving the efficiency know for a long time (Airbus guys teaching us about it during my studies 15 years ago), but creates additional difficulties, on top of which the impossibility to evacuate the plane fast enough. You would have the same benefits whether your plane is using hydrogen or kerosene.
I still do not see planes using hydrogen. Just doing the math on how much electricity would be needed makes it really unlikely.