Your point about the coal-generated electricity ... actually suggests NOT electrifying transportation widely until cleaner power supplies can be developed. Electric cars, for instance, are good in CA because of the relatively clean power supply mix, but not so good in Eastern states where coal burning is still a major contributor. Conversion to natural gas in recent years has reduced that coal effect considerably, but it's still present; if enough coal is used, electric cars can be worse for air quality than using standard emission-controlled gasoline-powered stuff! Yes, TMI for the true believers ...