For both air and sea there are quite a few other issues to consider:
-regeneration from capturing turbulence, using wing flex for airplanes, wave modulation in ships;
- complete restructuring of airplane temperature management, i.e. at altitude no more turbine heat capture for cabin temperature management;
-new approaches to inflight deicing;
-new approaches to all operational systems in both ships and airplanes.
-Totally radical approach to regulation (FWIW existing regulations for aircraft and pilots are established in terms of engine type) even imagining an electric aircraft forces everything to change.
There's much, much more.
A close friend of mine is working on a the aircraft solution. A decade in they're making progress but there are many technological problems to solve.
Battery advances are actually less difficult to solve than are a host of other issues, not all of which are even close to complete definition much less solving.
- some examples:
. aerodynamic advantages are very substantial when eliminating engine weight and drag;
. especially long distance, fuel weight can be in excess of useful load.
. Boeing 787-900 one of the most fuel efficient long range large airplanes today, must carry about 50% of useful load in fuel for a typical nine hour flight (I actually flight planned for GIG-MIA because I've memorized the data, having flown it regularly. I hold an Airline Transport Pilot rating and used flight planning software for the purpose)
Those facts explain why Airbus makes large investments in research and experimental airplanes, it also explains why the first commercial ones will be short range commuter airplanes. Above all that is why Tesla, to date, is concentrating on other more mature alternatives.
Frankly the impediments are the same for aircraft as they have been for cars and trucks, which is that the established makers all want to put batteries in an existing product and expanse that to work. As Tesla repeatedly has proven and just has again with Semi, build for purpose is the only solution.
Tesla, as we often note, has huge potential addressable markets in many areas. The Limiting Factor, as Elon says so often, is finding enough qualified engineers. As we so often point out, even within only cars Tesla has only scratched the surface, and trucks even less, energy impeded by raw materials shortages. And, in all of them, there are major issues in scaling o support.
This post is primarily to suggest that it is quite academic, at best, to discuss new product categories since the present ones are so replete with opportunity. That said, we also know that our CEO always is attacking new topics. Since there's already SpaceX, The Boring Company, Neuralink, Starlink and 'a bluebird that is not a bus company or ancient Datsun' it may be unwise to suggest promoting expansion of existing Tesla products to conquer market share for Tesla like the existing market share of SpaceX.