>>1550438>hydrogen Bad idea, it requires either ultra high pressure vessels that don't realy can take the shape of wings or ultra low temperature cryogenic storage that requires good insulation.
Even with these options it's still not exactly dense and doesn't even have the better ISP it doesin rockets.
If you wanted to run a plane on alternative non-fossile fuels there are good 3 options:
>methaneAlso needs cryogenic storage, but on a higher, more manageable temperature, is also denser.
>ethanolEthanol is a pretty simple biofuel that can be produced from waste cellulose aka the stuff from plants we humans can't eat.
>RMSRapeseed methyl ester aka biodiesel.
It burns cleaner than conventional diesel and would work in most engines without major changes.
For short distance planes "city hoppers" or however you want to call these <1h flights, electric propulsion might be an option as the mass fraction of fuel/batteries required for the short range is relatively low.
Meanwhile electric drivetrains are very efficient, low maintainance and reliable.
The plane could charge at the airport while boarding takes place.
Emissions regulations for planes are overdue, there are stil Boeing 707 flying around and leaving trails of soot behind them.
I'd propose we regulates particulate count and NOx emissions first as CO isn't realy an issue.
