The battery system for the LEAF was on display at a groundbreaking in Smyrna. The plant will be located behind the existing assembly plant.

Nissan only broke ground on its battery plant in Smyrna last week which will produce a power source for electric vehicles. But already, engineers are envisioning alternate uses and second lives for the batteries.

The useful life for these 660-pound batteries is expected to be about a decade. At that point, the capacity will drop by 20 or 30 percent – depending on the owner’s habits. Drivers may not want a car that can only go 70 miles between charges, but Nissan believes someone will probably want the battery inside for storage at solar fields or wind farms.

Nissan’s Mark Perry says the batteries could also act as a back-up power source by charging overnight when power is cheap and consumption is low, then be on standby during the day.

“It’s that 110 degree day, all the air conditioning running, you got peak load on the system. All the sudden the utility company says I’ve got all these battery packs out there I can pull energy out of and reduce my peak.”

The LEAF will be assembled in Smyrna. The batteries will be built in a new facility at the same site.

Even further down the road, the vehicle batteries could offer a source of energy while they’re still inside cars, Perry says.

“Longer term, there’s going to be a future, we think, where you as a consumer, just like you sell solar power back to the utility company, all this energy, you’ll be able to sell it back to the utility company.”

Right now, when a utility company like TVA needs more power, it fires up one of its gas-powered plants. That can be very expensive. Instead, Nissan believes power companies could pull from thousands of batteries that were charged overnight when demand on the grid was low.