Some might mistake the Toyota Scion parked in Willett Kempton’s garage as just another boxy import.
For Kempton, a renewable energy professor at the University of Delaware, the car is a rolling power station. He calls his Scion the eBox.
For the past 11 years, Kempton has been developing vehicle-to-grid, or V2G technology. He envisions a day when parked electric cars will give back to the grid when not on the road. His converted, battery-powered Scion can send up to 19 kilowatts of power back to the grid for about an hour and a half. That’s enough to power a small neighborhood, assuming Kempton’s assertion is true that homes use about 1.5 kilowatts at any given time. Homes in the Northeast use on an average about 20 kilowatts of electricity a day, according to the Energy Information Administration.
The true value of V2G, according to Kempton, is the ability to shoot short bursts of electricity to stabilize the grid’s frequency. Utility managers like predictable flows of energy. Spikes in demand can lead to brownouts.
Kempton’s give-and-take approach to power use has generated interest from corporate backers. Google kicked in $150,000 to help Kempton scale up his project, part of Google’s $10 million mission to accelerate plug-in hybrid and V2G technology.
Last year, Kempton formed a coalition of energy and technology interests called the Mid-Atlantic Grid Interactive Cars, or MAGIC. Coalition members include California electric car maker AC Propulsion; Washington, D.C., utility Pepco; New Jersey environmental group the Atlantic County Utilities Authority; and the University of Delaware.
With enough electric cars and two-way power stations, you could create a large, dependable electrical storage resource, Kempton argues.
His car communicates to the power grid, telling it when it needs juice and when it can discharge electricity.
“If there’s a loss of power at the grid,” says Kempton, “the car shuts down immediately, protecting the battery from total discharge … and most importantly, protecting line workers.”
While hybrid cars from Ford, Toyota and others use fossil fuel more efficiently than conventional internal combustion engines, they don’t return power to the grid. Kempton believes he can make a strong business case for V2G cars. A parked V2G car feeding back to the grid can generate revenue for its owner.
Solar power only works when it’s sunny. Wind power is erratic. Kempton believes V2G can provide a dependable source of power to balance the fluctuating output of these alternative renewable energies. Wide use of V2G electric-drive vehicles could generate enough power to cut the requirement for central generating station capacity by as much as 20 percent by 2050, says the Electric Power Research Institute, a utility industry research center in Palo Alto, Calif.
Skeptics point out that Kempton’s system would require a lot of idle cars. Kempton cites studies indicating that most cars are idle 90 percent of the time on any given day. He hopes to expand his experiment beyond his garage and have a demonstration fleet of 300 V2G cars operating in the future.
Other critics note that cars weren’t meant to serve as mobile power plants. A Honda spokesman told The New York Times last year that people shouldn’t use their Honda hybrids to power their homes. “Instead,” the spokesman said, “they should buy a Honda generator that was made for that purpose.”
