This has been proven false back in like 2008. Even if electric cars were to run off coal plants, they would still be more efficient because the plants can capture and reuse heat with boilers.
That being said, coal has to go anyway.
I run my electric car from 98% hydro power and 2% wind power and I pay 6,9 cents per kWh, and that's Canadian money, pretty cheap.
Right now, even with surge, they seem to be a bit cheaper than the normal city taxi but I would bet that as soon as there will be no more competition they will raise the price AND still do price surge. In the end, we will pay more than we used to.
Uber seem to be always on the edge between aggressive profit and shady business.
EDIT: Don't think by my comment that I meant the taxis are better. I was just saying that right now, this is a great deal in most cities where Uber does offer their services but seeing how hungry they are for max profit, I doubt this will last and eventually we will realize that a broken system was replaced by another broken one.
That being said, coal has to go anyway. I run my electric car from 98% hydro power and 2% wind power and I pay 6,9 cents per kWh, and that's Canadian money, pretty cheap.