When the Chevy Volt hits dealerships next month, it will have a 16-kilowatt-hour battery that will power the car for 40 miles, General Motors says. Like most rechargeable batteries, the one in the Volt will slowly lose its abiltiy to store energy, though; G.M. will give the battery a warranty for eight years and 100,000 miles, although it says it should last 10 years.
At that point, its storage capacity will be down to roughly 10 kilowatt-hours, according to the company. What happens then?
On Tuesday, G.M. and the ABB Group, the electrical equipment manufacturer, said they were exploring whether worn-out batteries could have an afterlife on the power grid. That 10 kilowatt-hours is still a lot of energy, after all — roughly what a single-family house uses in eight or 10 hours. And even if the speed at which the battery can deliver the current declined, it would probably be fast enough for electric utility use. (With car batteries, one of the challenges is to deliver energy fast enough to accelerate a car to highway speeds.)
A market for used batteries potentially could help G.M. sell new Volts, given that the battery pack is not expected to last as long as the rest of the car does and the cost of a replacement pack would be substantial. A buyer might like to know that the old parts would have trade-in value.
How much remains clear. The Volt is supposed to sell for $33,500, after a $7,500 federal tax credit, and a significant part of that cost is the battery. At current prices, buying 16 kilowatt-hours might push the price well into the thousands of dollars.
A G.M. spokesman, Kevin Kelly, would not say what the old pack would be worth or what a new one would cost; one wild card is that the battery technology is still changing. The cost of batteries is likely to be lower in a few years than it is now as production volume rises, he said. By the time a new Volt needs a new battery, the technology could have changed enough that a smaller, less expensive one would do the same work as the ones G.M. uses today. How the trade-in would work is not clear at this point, either.
But what could another company, one that did not particularly care about the weight or size of the pack, do with it?
Bob Fesmire, a spokesman for ABB, said that he would not speculate because that might tip off competitors to his company’s ideas. But the obvious use is to link them to another growing technology, renewable energy from intermittent sources like the wind and sun. Some utilities are already exploring the use of batteries, not so much to store power for when it as needed as simply to slow down the rate at which renewable generation waxes and wanes.
Batteries could also be used for simple storage at a utilty substation or in a house. But batteries store energy as direct current, and household appliances use alternating current, so a device called an inverter would have to sit between the batteries and the grid. A customer who wanted batteries in the basement as a back-up source could buy an inverter, but a customer using solar cells could install batteries more easily, because solar cells already have inverters.
G.M. is collaborating more and more with utilities as it seeks to work out a system so that the power grid can “talk” to the car, charging it up at hours when prices are not at their peak level. But this is its first major collaboration with a company that supplies utility equipment for power production and distribution, Mr. Kelly said.
The significance of the effort is not yet clear because the number of volts that G.M. can sell is not yet obvious. And even if the car sells well, it will be some years before a lot of battery packs are available, Mr. Kelly noted.
The exception would be a few from vehicles that were totaled in crashes without damage to the packs, or those from warranty returns, he said.
So for the moment, the two companies are investigating how to recycle a product that barely exists at the moment, the plug-in car, to meet a need that also barely exists, to smooth out the electricity flow from renewable sources.
By MATTHEW L. WALD/NYT