But what many experts are excited about now is a concept called “vehicle-to-grid,” often abbreviated V2G. In such a system, plug-in hybrids, rather than being merely an extra burden to the grid, become a much needed way for grid managers to balance the amount of energy generated at any given time to match the amount of energy being consumed. Millions of cars, each with several kilowatt hours of storage capacity, would act as an enormous buffer, taking on charge when the system temporarily generates too much power, and giving it back when there are short peaks in demand.
In a V2G system, the batteries of millions of plug-ins would be used as a buffer to even out supply and demand and to help keep the grid stable, says Karl Lewis, chief operating officer of GridPoint, a startup based in Washington, D.C., that has developed technology that could help make such a system work. In this kind of system, each vehicle would have its own IP address so that wherever it is plugged in, the cost of the energy it uses to recharge would be billed to the owner. With the right equipment, the car could also return energy to the grid, giving the owner credit. Mock-ups of such systems have already been tested by the National Renewable Energy Laboratory (NREL), in Golden, CO, and by a company called AC Propulsion, based in San Dimas, CA.
Plug-ins could also serve as backup sources of power. In extreme cases, such as a blackout from a hurricane, the cars could keep essential systems up and running in homes and businesses. Even in this case, when the batteries could be drawn down considerably, the owner could rely on the internal combustion engine in a plug-in hybrid for transportation.
As an added benefit, “if millions of these [plug-in hybrids] were produced, it would enable some of the renewable technologies to really take off,” say Terry Penney, a technology manager for advanced vehicle technologies at NREL. The challenge of using a renewable source such as wind is that wind is intermittent, varying day by day and minute by minute. A network of plug-in hybrids could smooth out these fluctuations by storing extra energy and sending it to the grid when the wind dies down. Such a network would also improve the economics of wind power by making it possible to capture more of the excess power generated on windy days, says Willett Kempton, senior policy scientist in the Center for Energy and Environmental Policy at the University of Delaware.
Such systems are many years off, as it will take time to install the needed infrastructure. Once plug-in cars are widely available, however, they could help relieve some of the pressure on the grid today.