why is relocating smog and all of the industrial waste associated with the production of a new bus and bus batteries a "public benefit"? Diesel engines last a l

why is relocating smog and all of the industrial waste associated with the production of a new bus and bus batteries a "public benefit"? Diesel engines last a long time, as do bus bodies, I don't have first hand experience managing a fleet but I'd be very interested to know how the pollution stacks up--is generating, transmitting, distributing, and storing the power, with all the losses incurred, along side making the batteries, which I assume wouldn't last that long in a fleet vehicle, really that much better than just burning diesel? I need to see a spreadsheet or something.