https://www.vox.com/2019/3/1/18241489/electric-batteries-aircraft-climate-change

The y-axis also shows what would happen to fuel prices if a
$100-per-ton carbon tax were imposed. Electric airliners would only be as clean
as the electricity that charges them, so pricing carbon would be one way to
ensure that they aren’t trading emissions from jet wash for emission from a
smokestack.

Taken together, this means it will likely be decades before you can book a
flight powered solely by electrons. But it’s still worth hoping it takes off.