No one ever mentions Trolley buses as a solution for Urban Public transport.
Because they aren't sexy big ticket projects or magical battery solutions.
Because trolleybuses have most of the disadvantages of trams and most of the disadvantages of buses, with few of the advantages of either.
Like a bus they have capacity limited by maximum vehicle length, higher rolling resistance on rubber tyres, and do not follow a precise path so more difficult to integrate in pedestrian areas.
And do not follow a precise path so don't require enormously expensive reinforcements of the road surface or enormously expensive in-street infrastructure. Electricity is not a major component of the operating cost of a tramway or trolleybus route and thus the slightly greater losses are irrelevant.
Trolleybuses can also handle any climb a normal bus can, and can often do it more rapidly, allowing them to use any existing bus route as long as overhead wiring is put up.
With the huge automotive market behind them I'd expect batteries and fuel cells to make huge advances in the next few years. Just look at what's happened to the price of solar panels since they became mass-market items.
So, like solar panels, they will go from hopelessly uneconomic to simply extremely uneconomic? After fifteen years of massive state support solar panel installation is still a zombie industry propped up by enormous government funding with no real prospect of that changing.
Trolleybuses are dead in the UK apart from at a handful of museums, and the principle reason for that is the ongoing development of electric buses. They're not quite there yet, but it won't be long until an electric bus is capable of the range required for a full day's work on urban routes. The Chinese claim that they can get nearly 300km out of one on a single charge already, although this claim is best taken with a pinch of salt.
Recharging all the buses in the depot with the really really short turnaround times bus fleets can expect these days is going to be
interesting.
We will probably need 33kV circuits deployed to the bus depot, if you have a hundred buses, all of which are trying to recharge 300kWh+ batteries in about six hours of turnaround. You are going to need 5MWe at the least, plus resistive losses and some
enormous bus [heh] bars.
And if you want shorter turnarounds, and many bus routes do seem to in Manchester at least, that number will rise rather steeply.
Enormous quantities of high voltage infrastructure woudl be required, all of which has to be paid for.
Meanwhile you can build a trolleybus route using the Portland Streetcar substation philosophy using entirely low voltage equipment at surprisingly low capital cost.