When electric vehicle batteries get long in the tooth, they have to be replaced because they’ll start experiencing power loss—which will mean reduced vehicle performance. But what happens to those old batteries after they’re replaced is important if you’re judging a car on how environmentally friendly it is.

To this end, automaker Daimler recently announced that it plans to connect the old lithium-ion cells to the grid in Lünen, Germany, building the world’s largest stationary storage facility made out of re-used electric vehicle batteries. The system will allow renewable energy that's generated in that area to be stored and given back to the grid to level out energy fluctuation that might occur if, say, those same generating sources went offline due to equipment failure, a cloudy day, or a drop in wind power. Generally, burning extra fossil fuel is required to stabilize the grid.

"Depending on the model, Daimler AG guarantees its electric vehicle customers a battery life of up to ten years, “ the company wrote in a press release. "However, the battery systems are still fully operational after this point, as the low levels of power loss are only of minor importance when used in stationary storage. It is estimated that the unit can operate efficiently in a stationary application for at least another ten years."

Daimler’s first stationary storage unit will be able to provide 13MWh of electricity and is slated to come online in the beginning of 2016. A spokesperson for the company told Ars that “further projects are already being planned.”

The company also noted that it’s working with a number of other companies to get the project off the ground—it’s not as simple as wiring together a bunch of old batteries and calling it a day. Daimler said its subsidiary Accumotive will reprocess about 1,000 old lithium-ion batteries, wiring them into groups of 46, with each group providing 600kWh of energy. The storage unit will offer state-of-the-art battery management (according to Daimler’s press release) and a water cooling system.

Two outside companies will help the Mercedes-Benz maker market the battery capacity to German utilities, and a third, called Remondis, will recycle any salvageable raw materials after the batteries’ second lives have run their course.

Daimler isn’t the first company to think of this—earlier this summer, GM showed off five sets of battery installations, using old batteries from Volt cars, at its Milford Proving Ground in Michigan. But Daimler's efforts do seem to be the most serious attempt thus far to put electric vehicle batteries onto the grid.