There is simply no way that tens of millions of cars, trucks and even tractor-trailers will be able to hook up for a charge all at once, day in and day out, without killing the grid and leaving the entire state in the dark.

Researchers from the University of California Irvine (UCI) say they are trying to figure out how to provide enough electricity to charge all those cars once the rule comes into effect.

"The grid does not currently have the capability to add millions of battery-electric or even fuel-cell electric vehicles today," says Jack Brouwer, a professor of mechanical and aerospace engineering at UCI.

"So, we have some time to make reasonable investments in the grid to enable this to actually happen and to happen well."

Southern California Edison (SCE), an electric company that provides power to some 14 million customers, says it is making those investments right now – but will it actually work?