Am I completely off base, or does this back-of-the-napkin calculation make any sense?
There are about 7,000,000 cars in Ontario.
Ontario’s peak capacity is maybe about 25,000 megawatts.
Our night draw is about 15,000 megawatts (same source).
This makes a difference of 10,000 megawatts.
A Nissan Leaf has a 24 kilowatt per hour battery. At 240 volts it takes about six hours to charge.
So that means 1000 Leafs would require 24 megawatts to charge.
Divide that by the six hours it takes to charge is 4 megawatts of a draw if all those 1000 Leafs are plugged in at the same time (let’s call that a kiloleaf for fun).
10,000 megawatts divided by 4 megawatts is 2,500 kiloleafs, or 2.5 megaleafs.
Therefore, our current electrical system should be able to handle 2.5 million Leafs all plugged in at the same time at night. Once the number of electric cars (or plug-in hybrids) approaches 35% of all vehicles on the road in Ontario, we might start running into problems.
Of course not everybody will need to plug in every day when if car has a range of 160 km. If most people can hold off on charging every third day, then those numbers would fit together very snugly. Neato.