My feelings on SAF are really that it can't be produced in sufficient volume for the industry, added to the fact that any production might potentially take foodstuffs away from actually feeding people. It's a bit pie in the sky and most likely a greenwashing exercise by the industry who know that the writing's on the wall for aviation in its current form.

On hydrogen, I think it would require such an extensive and expensive amount of new infrastructure for domestic vehicles that I don't think it's economically viable - for larger vehicles perhaps - but not for cars.

I'm be interested to know how you think it can be converted to a liquid at room temperature as it's extremely hard to do due to its chemical nature and leaks from practically any connector or valve.

Good luck with your crowdfunding!