In Moscow, there was a transition to electric buses. They are cleaner than buses, although the power reserve is significantly less. Trolleybuses, which were also replaced, greatly spoiled the view with wires and poles. Everything would be fine, but in the cold season (which is 6 months), heating of the passenger compartment and the driver's cab is necessary. for example, recently during the week there was a temperature of -25 degrees.Celsius.
It wasn't a problem before: The internal combustion engine emits a lot of heat, and trolleybuses were supplied with a sufficient amount of electricity by wires. But we had to put autonomous furnaces on electric buses, which now use diesel fuel. It's quite expensive and not too eco-friendly (and it smells). And now the idea is being worked out to use used fryer oil from a fast food chain (an analogue of McDonald's).
Not to say that these are all big problems, but it's funny.