I did not know until just now that the US Navy is working on synthesizing jet fuel from sea water. Sounds like one of those schemes advertised on YouTube, but here is a press release from the Naval Research Laboratory:
NRL Press Release
The process uses a lot of electricity, but nuclear-powered carriers have a lot of electricity available.
Smithsonian magazine (a bit of a rag) gives a production cost of between USD3.00 and USD6.00, which is expensive for fuel but saves the cost of replenishing at sea.
This looks like a viable route for the electrification of aviation, using sustainable electricity (off-shore windfarms, perhaps) to synthesize fuel appropriate for aircraft.