Hybrid Cars That Can Power Your Home?
V2G technology could power homes from plug-in electric cars.
The AC Propulsion’s eBox, operating V2G in the University of Delaware’s electric vehicle parking spot.
March 20, 2009 by Steven Castle

You’ve no doubt heard of powering your home by solar panels or a wind turbine. But how about powering up that home theater system by plugging in a hybrid electric car?

The idea is that the batteries in a new breed of plug-in hybrid vehicles (PHEVs) could be used to provide energy to a smart grid during times of peak energy use. So instead of just using electricity from the grid to charge car batteries, the power stored in the batteries can also help provide power for the grid.

The concept is called V2G, or vehicle-to-grid, and trials are already underway. A retooled Toyota Scion xB now called the eBox, is already under the control of the grid at the University of Delaware, and chances are, you’ll be hearing a lot more about this technology.

“Electric-drive vehicles, whether powered by batteries, fuel cells, or gasoline hybrids, have within them the energy capable of producing the 50 Hz or 60 Hz AC electricity that powers our homes and offices,” says the Mid-Atantic Grid Interactive Cars Consortium (MAGICC) web site. “A fully electric car can draw or produce up to 19 kilowatts, the average power need of 13 U.S. houses.”

Kenneth Huber, manager of advanced technology at electricity wholesaler PJM Interconnection, which services 13 states, embraces the idea of V2G. He says utilities could quickly adjust and regulate regional electricity loads using the energy stored in cars, in milliseconds, whereas adjusting the output from coal-fired-power plants, which produce about half of the electricity in the United States, takes minutes.

That would take a lot of electric cars being plugged into a smart grid, which we are likely to see in the coming years.

“If you look at 176 million cars in United States, they are a huge energy resource of about 1,760 gigawatts which is over two times the total U.S. installed [electrical] generating capacity,” says Steven Letendre, associate professor of management and environmental studies at Green Mountain College in Vermont.

One of the main concerns of a new smart grid, however, isn’t to borrow power stored in cars, but charging them without running out of electricity. There’s a potential for many of us to come home in the early evening and plug in our electric vehicles, causing peak loads at utilities and possibly brownouts. That’s where a smart grid that encourages people to charge at off-peak hours, perhaps with lower rates, comes in.

“Through smart charging and timed charging, you can actually accommodate a lot of PHEVs being charged,” says Letendre.

Energy expert Jim Dunn, of Energy Technology Consultants, says that a study done by Pacific Northwest National Laboratory shows we could accommodate up to 200 million PHEVs if they all charged during the night at off-peak times.

Dunn isn’t sold on cars being used to power the grid, though, citing challenges such as the costs to set up such two-way power transmission and the intricacies of establishing all of the interconnections necessary.  “There may be more practical options, such as storing excess energy from wind farms,” he says.

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Steven Castle - Contributing Writer
Steven Castle is Electronic House's managing editor. he has been writing about consumer electronics, homes and energy efficiency topics for two decades. He is also the co-founder of GreenTech Advocates.

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