Can a city run on car batteries? The 'vehicle-to-grid' idea might just work

When Damien Maguire moved to the countryside outside Dublin, he struggled to keep the lights on at home because of the town’s constant power outages. He found a solution inside his electric cars: their batteries.

A tinkerer who posts videos of his hand-built vehicles on Youtube, Maguire devised a wiring system that lets him suck power out of them when they’re parked in the garage. Now that the house and cars are connected, he can also use the batteries to store energy from his backyard solar panels, another power source that’s not totally reliable given Ireland’s weather.

“You have the light-bulb moment,” said the 41-year-old electrical engineer. “There’s a big battery in the car, so how about I use that?”

An even bigger light-bulb moment is happening for utilities and automakers, who want to use the batteries inside electric cars as storage for the entire public power grid. The idea, known as “vehicle-to-grid,” is to someday have millions of drivers become mini electricity traders, charging up when rates are cheap and pumping energy back into the grid during peak hours or when the sun simply isn’t shining. If it works — and it’s a big if — renewable energy could get much cheaper and more widely used.