You can always find unrealistic and worst-case scenarios, like magically converting 50% of the cars in coal-powered Illinois to electric, that will overburden the current grid and generation capacity.
The fact is that most EVs will charge overnight. Not all... mine doesn't, because I don't have a garage or driveway. But most will, and even with zero improvements to the grid you could convert 20% of the North American fleet with almost no impact to peak daytime demand.
As an engineer, driving both my daily EV and various combustion vehicles has really impressed upon me the efficiency of the EV. The power generation is more efficient, the power transmission is more efficient, the powertrain is more efficient. The friction brakes on a standard vehicle are an insult to thermodynamics.
Think about all the things that burn and pump and radiate in your average combustion engine and transmission. I can drive to work on the Interstate and when I arrive, no part of my car is too hot to touch.
The EPA clumsily tries to equate fossil-fuel power to electric power by giving EVs an "MPGe" rating that tries to compare the efficiency of EVs to fossil-fuel vehicles. My Focus Electric gets "105 MPGe", compared to Ford's very best 1 liter EcoBoost at 35 MPG.
Did I get a tax break on my EV ? I sure did. Don't get me started on the cost in dollars, carbon, and blood that are hidden in every gallon of gasoline.