After cars, there is a second life for batteries

Generator, boat propulsion, electricity storage... As electric vehicles multiply on the roads, car manufacturers are already thinking about a second life for batteries, in order to reduce their carbon footprint.

For a few years now, the sales of electric vehicles have taken off in the world. The lifespan of batteries for automotive use is estimated at about ten years and around four million electric cars are expected to be withdrawn from the market in 2030, according to a study by the Boston Consulting Group.

Batteries are still good for other uses, with still 70 to 80% of their available capacity. But which ones?

They can help to regulate the electricity grid, at a time when solar and wind power, renewable but intermittent sources of energy, are developing.

Since 2018, German automaker BMW has been operating batteries recovered from its old i3 electric cars, which have been running since 2012, to store the energy produced by four wind turbines in Leipzig (east of Germany) and then inject it into the public electricity grid.

"The goal is to maintain stability on the public grid" and to meet peak electricity consumption, Holger Reiche, manager of this installation, told AFP.

Similarly, Renault has "battery farms" at its sites in Douai (northern France) and Flins, near Paris, that will ensure this function, according to Jean-Denis Curt, circular economy expert at the French automaker.

Another possibility: Audi, a subsidiary of the leading European automaker Volkswagen, uses used lithium-ion batteries in its fast-charging stations powered by solar panels.

Volkswagen has even launched itself into the electricity market as part of a pilot project. "It is important to gain experience in the management of stationary storage with batteries", with the long-term "clear objective of developing a significant and profitable activity", explains a group spokesperson.

Energy storage with used batteries can be used on a smaller scale, to replace a diesel or gasoline generator. Renault supplies used batteries to the German start-up Betteries, which transforms them into a "mobile storage system, on a wheeled cart", that can be used on construction sites or even at festivals, describes Jean-Denis Curt.

In another sector, used batteries can be used to electrify barges or tourist boats such as the bateaux-mouches in Paris, he continues.

Are all electric vehicle batteries destined for a second life?

"It's not a done deal, there are technical and economic challenges to overcome," nuances Damien Pierre Sainflou, in charge of these issues at French automaker Stellantis.

In Rennes (western France), a dozen batteries are being stripped down in the Stellantis factory, as part of a pilot project. The goal is to learn how to safely recover the elements and to establish a battery diagnosis before reuse.

Solving the technical issues is not everything. For the groups that are launching into battery reuse, it has to be profitable. However, in the long term, "we will have new battery technologies that can be used for wind and solar storage that may be cheaper than using old car batteries," notes Matthieu Noël, of the consulting firm Roland Berger.

Another possible competition is recycling. "The more demanding the regulation is on the proportion of recycled materials to be used in new batteries, the faster there will be a need for these recycled materials," which could lead to dispensing with a second use of batteries, says Eric Kirstetter, of Roland Berger.

But for Holger Reiche of BMW, "the second life is absolutely more profitable, because a battery lasts 10 years in a car, then another 10 years in stationary storage, and can then finally be recycled, which extends its lifespan."

Sophie Molina of the company Entech, which collaborates with Stellantis, agrees: "Will the second life have a place? I think so because the needs will be huge and the interest is not only economic, but also ecological."

Thus, we can say that the re-use of electric vehicle batteries is a promising solution to reduce the environmental impact of these vehicles. However, there are still technical and economic challenges to overcome before it can become widespread.