"Dig more coal...the Teslas are coming."
One of his major sources is eia.gov, and their 2015 report has electric power use at 38% of total use.
Transportation is another 28% of total energy use, so the sooner that can switch over the electric, the sooner we can drop the 36% of energy being sourced from petroleum.
That 35.4% carbonfree electricity can be broken down into: 19.8% nuclear (this part we really should fight to keep operating as long as possible, certainly until we shut down every fossil fuel plant... going from 80% renewables to 100% renewables may actually be harder than going from the current 15.5% to 80%).
7.6% wind, geothermal, small hydro, and maybe some biomass (unfortunately, EIA doesn't break these out separately)... though most of this is wind and geothermal
6.7% conventional hydro.
1.4% solar. (and this includes distributed solar)
AS recently as 2003, over 50% of our electricity was generated from coal. We're now at 30.5%.
As long as we keep nuclear operating, it should be fairly cheap to squeeze out the rest of that 30% of coal by installing high capacity factor wind turbines where it's windy (and perhaps anti-correlated with other sites), lots and LOTS of cheap utility-scale solar, mounted on single-axis trackers to increase capacity factor, and lots in Texas and the American South where it's not already common.
Adding 15% additional grid penetration of solar and wind both, along with probably some storage (lots of pumped hydro in Appalachia to replace coal, batteries everywhere else) to smooth out demand and UHVDC powerlines and East-West interconnects, we can squeeze out the rest of that 30% of coal without huge costs.
If we try to do this without that ~20% nuclear, we'll either need a lot more gas or a LOT more money.
but it's not a 1:1 relationship. A lot of electricity in the US comes from burning petro-fuels like natural gas (if you count natural gas as a petro fuel) or coal.
There was a study[1] last year that argued that driving a Tesla in Ohio caused more pollution than driving a BMW 3-series, because the source of the Tesla's electricity was likely coal.
1: https://www.scientificamerican.com/article/electric-cars-are...
In general, it looks like even in the dirtiest states, driving an electric car is about as efficient as a 40mpg car.
The argument also goes that electricity generation only gets greener so your electric car actually pollutes less over its lifetime, unlike a conventional gasoline powered car.
1: http://www.ucsusa.org/clean-vehicles/electric-vehicles/life-...