I think Harbour Air's electric Beaver is the real deal. The numbers can be made to work for the 20 minute scenic flights they do all summer and the Vancouver - Nanaimo sched ( 32nm), assuming a 1 hr turn time for a fast recharger at the dock at Vancouver and Nanaimo. One advantage is that conventional airplane parts are stupid expensive ( eg 50,000 USD for an overhauled Beaver engine good for 1600 hrs) so expensive bleeding edge technology can still be cost effective.
The bigger challenge is that so far battery technology has increased incrementally. To make electric power viable for more than specialty niche applications like what Harbour air wants to do, you need batteries 10 times more power per kg than what is presently available and there is nothing like that on the horizon.