For example, car owners could specify what time their car needed to be charged by and the highest price they were willing to pay for electricity. Some people will prefer to have the car charged immediately, and so would be willing to pay whatever the price happens to be. But others might be more concerned with keeping costs down, or even in promoting the use of renewable energy, says Luke Clemente, GE Energy's general manager for smart grid. These people could program the charger to recharge the car when the price for electricity is very low--that is, at times when utilities have excess capacity. Once there are large numbers of smart chargers in use, this would create an instant market for that surplus power, helping to balance supply and demand, which is essential to keeping the electrical grid up and running. Similarly, if the power supply drops--for example, when the wind suddenly stops blowing--utilities could quickly increase prices, causing smart chargers to pause charging, and thus lowering electricity demand.

The GE charger can also deliver power stored in a car's batteries back to the grid during emergencies, such as when demand spikes or a power plant goes down, Clemente says. Car owners who allow utilities to draw power from their cars could get discounts on electricity rates. This feature probably won't be used for many years, however. It could require special wiring and switches in homes and new regulations governing this two-way flow of power, and it could decrease the longevity of car batteries, raising concerns about warranties.

At first, smart chargers won't be necessary--it will take some time for electric vehicles and plug-in hybrids to be on the road in large enough numbers to significantly affect the power grid. Meanwhile, Kinter-Meyer says, it will be important for smart charging systems to be implemented in a way that consumers, not utilities, have ultimate control. That way consumers can count on their cars being charged up when they need them.