Use as a trainer makes some sense for a battery aircraft - relatively short flights that generally return to the departure airport to get recharged for the next lesson.
Long range intercontinental transport is a completely different story. Given foreseeable technology, biofuels are the way forward. I saw an interesting paper roughly ten years ago about jet fuel from algae - they were already able to produce biofuel from algae that was nearly indistinguishable from Jet A. It has a number of advantages over vegetable oil based fuels - it required a small fraction of the land area, the algae literally ate sewage, and required much less processing than vegetable oil based fuels. While not quite carbon neutral, it was pretty close (much closer than any other proposed bio fuel). At the time Boeing was a participant in the study.
At the time, the biggest drawback to large scale production was it required large amounts of fresh water, but they were working to develop an algae variety that would work with sea water. That and of course cost - it need petroleum to sell for over $100/barrel to be economical.