We might save money if we harnessed solar and wind to displace all our coal and all the gasoline used for light duty vehicles (cars, SUVs, pick-ups). Let’s see how this works.
The US uses about 4000 TWh of electricity, and about half of that comes from coal (about 2000 TWh/yr from about 23 Quads of primary energy).
Our light duty vehicles require 17 Quads of oil, but only 3.4 Quads of it actually gets to the vehicles and moves them (20% efficiency from oil to movement). At ~300 TWh per Quad, this is about 1000 TWh of energy. If we did it with electricity and assumed 25% losses (electricity to batteries to motors to movement), we would need about 1333 TWh to move our light duty vehicles without oil. The total to displace both oil for cars and coal would be 3333 TWh. Let say this takes 25 years, so let’s assume 33% more demand by then (perhaps not warranted, since we may be saving energy, but just to be conservative) – that would be 4444 TWh in 2035. (This should be rounded, but it’s such a charming number, we’ll use it as is.)
So how much would this cost? Let’s do half with solar, half with wind.