SAN DIEGO -- The white Toyota Scion xB parked in a corner of the vast convention center here doesn't look too unusual, until you notice the fat cable plugged into its bright orange front grille.
But its owners say it might be the smallest unit of California's electrical grid. The car, a plug-in hybrid electric vehicle, has been retrofitted by AC Propulsion to respond to signals from the California Independent System Operator -- giving it the ability to send power from its battery back to the grid.
It's on display here at the annual meeting of the American Association for the Advancement of Science as proponents of so-called "vehicle to grid," or V2G, technology make their case.
Backers say V2G could help balance the country's supply and demand for power, especially as renewable energy from intermittent sources like wind and solar becomes a larger part of America's energy mix. With enough cars participating, a V2G system could help buffer ups and downs in power production by allowing utilities cheap storage for their excess power.
"One car doesn't make much difference," said Willett Kempton, director of the Center for Carbon-free Power Integration at the University of Delaware. "But when you have 100 cars or 1,000 cars, you actually start to talk about displacing power plants."
Kempton, who will give a talk today at the AAAS meeting, originated the V2G concept in 1997. He's also spearheading a project that's put three V2G cars on the University of Delaware campus, where they provide power to PJM Interconnection, which operates the electric grid for much of the Mid-Atlantic and Great Lakes regions.
The demonstration project -- known as the Mid-Atlantic Grid Interactive Car Consortium, or MAGICC -- is now "making money in the grid, actually collecting cash" for sending power back to PJM, said Kenneth Huber, the grid operator's senior technology and education principal. "Whenever these cars are plugged in at the University of Delaware, they're making cash."
Well-connected cars make money
Here's how it works. The cars on the University of Delaware campus are connected to PJM by an Internet connection. Every four seconds, PJM makes contact with the vehicles, allowing them to signal the cars to send power back into the grid in times of need.
"PJM is required to have 1 percent of its peak power on any particular day to be provided in frequency regulation at 60 megahertz," said PJM's Huber. "At the same time, people are turning on load and off load, so we have to move our generation up and down to match the load."
He compared it to a pond where water comes in and out, but the overall water level must remain constant.
The advantage of using V2G to help smooth out peaks and valleys in power supply, and demand is clear, Huber said. V2G-equipped cars like the retrofitted Toyota or those on the University of Delaware campus can respond almost immediately to signals from PJM or other grid operators -- a much faster response than can be achieved by rejiggering production at power plants.
For consumers, the lure is the ability to generate money as their cars sit unused, experts said.