[NotSammyHagar]

There are people researching it, I believe Airbus is about to test flying with hydrogen. It's the usual thing though for "green hydrogen", there's not much green hydrogen, there are some testbeds but just like for cars it seems to be mostly extracted from natural gas. You can extract it with any energy source like solar power. There's still the challenge that hydrogen fuel is not very compact, so it's hard to carry enough energy (in a car or plane) for much use, you end up with very very high pressure tanks. I think hydrogen will make sense eventually for trucks, tractors maybe. The question is will the massive investments in improving batteries make hydrogen vehicles obsolete or not.

There are also research programs about making fuel from other sources, like https://www.sciencedirect.com/science/article/pii/S016523702...

[nielsbot]

Answering my own question: Looks like there's something called solar fuel https://en.wikipedia.org/wiki/Solar_fuel