I've been trying, and failing, to find any published stats out there about how many bus operators, or municipalities etc., have made any progress on upgrading their fleets with low-emission vehicles (electric, hybrid or hydrogen).
Does anybody know if this information exists out there anywhere? I cannot express the degree to which I don't want to figure it out myself!
I can't help with wider operators, but Reading Busses are now running about 1/3 of the fleet on Methane.
On the (now unlisted) fleet listing, there is one that has been converted to electric too.
You might want to try the anoraks to help you with this one. Spotters keep records of a lot of provider fleets, and could give you an overview of where is now using electric.