Even if electric and battery technology is the solution, they're going to have to figure out a way to deal with the mind-boggling demands a city full of electric vehicles is going to place on the electricity grid... We already have infrastructure on the brink of collapse during summer heat-waves, with the energy authorities pleading with householders to minimise their peak electrical usage.
But at peak air-conditioning load in the afternoon/ early evening all those buses will be out on the road.
By the time they are back in the depot to 'refuel', the grid will be winding back and there will be spare transmission capacity.
Somehow, I don't think renewable sources charging monster battery arrays that then get transmitted again, only to charge another battery is the solution. There must be quite the efficiency loss between transmission to storage, using batteries and then retransmitting the power as it is demanded.
This is quite possibly why the Hydrogen option is still on the cards.
The Hydrogen cycle is not very efficient - even today's batteries can better the 'round trip' cycle of generating electricity, storage in a battery (or as hydrogen), transmission (transport) , decant and then conversion back to electricity. And the battery cycle has two cycles - grid-level storage and then on vehicle storage and it can still beat out hydrogen for end-to-end.
There will certainly be a place for a hydrogen cycle in certain applications, but it's not efficient enough to be the main energy conduit.
Storing cryogenically compressed hydrogen is hard. Compressing it to that level is hard. It has to be highly compressed and cold or you can not carry enough to do useful work. It's all well-understood stuff, but that doesn't change the physics.
And the cheapest way currently to make hydrogen is still 'steam reforming' of Natural Gas, where you strip off the carbon and throw it away (i.e vent CO2 to the atmosphere). Not very clean at all. Might as well burn the natural gas directly in a modified ICE and skip all the mucking about.