We had the debate somewhile ago on here - can't remember the thread - about electric buses in the Middlesbrough/Redcar areas and the potential issues, particularly out of Dormanstown depot. 

Services X4 and X93/4 would present challenges due to the length of the routes and terrain covered. Also some journeys on the X4 and all the journeys on the X93,/4 are operated out of Whithy outstation. Nothing,I suspect, that couldn't be worked around. 

Service 63, a mainstay prime route for Arriva would be an ideal candidate and potentially a flagship for Arriva electrification. Presently operated by the elderly Pulsars its crying out for new fleet. 

Service 5 out of Stockton? Again similar to the 63 but the downside could be the demands placed on electrics at the Loftus/Easington end of the route. Stagecoaches Yutongs seen to cope on their service 1 and 2.

Just a few thoughts, maybe open up a conversation about this??