Smarter Chargers for Electric Vehicles

This spring, GE will start selling a line of “smart charging stations,” devices that communicate with utilities to optimize charging, for electric vehicles. The technology could be key to ensuring that electric cars don’t strain the power grid, and it could cut down on consumer electricity bills. Eventually, because the charging stations could help stabilize the grid, they could allow utilities to rely more on intermittent renewable sources of energy such as solar and wind power.

The GE products come as automakers introduce a new wave of electric vehicles. GM, Nissan and Ford, for example, plan to start selling electric vehicles this year, and others will follow. While other companies already offer electric vehicle chargers, GE’s products could be important because they’re made to work with the rest of the company’s “smart grid” infrastructure, which stretches from the power plant, through the grid, all the way to smart appliances in the home. The company also has close relationships to utilities, which could speed adoption.

Electric cars could eventually have a big impact on electricity use–charging a plug-in vehicle would account for about 30 percent of a typical household’s electricity bill, says Michael Kintner-Meyer, a senior research scientist at the Pacific Northwest National Laboratory in Richland, WA. (He helped develop a smart charger for electric vehicles, which PNNL has made available for licensing.) If too many people decide to charge their cars during times of peak electricity use, it could force utilities to use expensive and often dirty “peaking” power plants to meet demand, or even threaten power outages.

Smart chargers could solve this problem. At the simplest level, GE’s chargers would let owners program their cars to delay charging until the middle of the night, when demand is low. As more utilities start to use “time-of-day pricing,” when they’d charge less for electricity in the middle of the night, for example, this feature could save customers money. But the chargers can also respond to real-time price signals sent by utilities to GE’s smart meters, which are now being installed in some homes. These signals would trigger changes in charging, making it possible for electric vehicles to serve as a buffer, smoothing out variations in supply and demand.

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.