I wonder how difficult it would be to build an airplane that runs off ethanol - until we get electric airplanes it might be a decent stopgap measure for the conscientious oligarch.
Tl,dr: ethanol has about 60% the energy density of jet fuel (so you need more fuel / weight for same flight), the extra weight may mean you actually have a negative available cargo weight (for passengers and their stuff) depending on the airframe, and it's a solvent that might melt the systems it's in, requiring an up-to complete retrofit of the drive and fuel systems for the airplane.
But maybe depending on the application, if you built an airplane from scratch to use it, there could be ways? It may be a very expensive airplane though, which could make it harder to run one to profit eventually.
I was envisioning a net-zero emissions private plane, a pure luxury item for frequent fliers where profit wouldn't be an issue - Depending on a celebrity's public position on climate change, that kind of signalling could be worthwhile.
