After Nissan, BMW and smart, Renault too is now reusing end-of-life electric car batteries. The aim is to store energy from domestic solar panels at low cost and release it during peak periods.
Spent batteries from electric cars are not a problem; on the contrary, they represent a resource. So says Renault which, following a path already taken by other manufacturers — for example Nissan, BMW and smart — argues that it is possible to refurbish the cells and put them to use in the home, turning every house into a mini power station for producing and storing renewable energy. In doing so, cells that would ordinarily be destined for disposal can enjoy a life cycle extended by at least fifteen years.
The reuse of battery cells is one of the key challenges that sustainable mobility will need to resolve in the short term. The Daimler Group, which owns the Mercedes-Benz and smart brands, has provided an "aggregated" answer to the issue — that is, it has allocated more than 1,000 batteries from the smart fortwo electric drive city car to the storage of energy produced from renewable sources, primarily wind and solar. The cells, specifically, were grouped together at a facility in Lünen, in Westphalia. Renault has taken a different approach: while pursuing the same goals, it has focused on the private and domestic dimension of storage systems.
The French manufacturer, in collaboration with Powervault — a division of the Dell Group specialising in energy and data storage — has reused end-of-life electric vehicle batteries, with around ten years of service behind them, to create a system for storing energy produced by residential solar installations at home. By drawing cells from both passenger vehicles and zero-emission commercial vehicles, it has been possible — on an experimental basis for now — to create a virtuous circular system: during periods of low demand the cells store energy, while when demand is higher they release their charge instead of drawing from the grid. A technology that calls to mind the Powerwall from American company Tesla, but which promises to be more affordable.
Why use already-spent batteries rather than brand-new units? First and foremost, to reduce the environmental impact associated with the production and disposal of modern lithium cells. Secondly, because automotive-derived cells, even after thorough use, retain a residual capacity of close to 80 per cent after ten years — ideal for residential storage systems, which do not require sudden power peaks and have no need for rapid charge/discharge cycles. And finally, because in doing so home storage with refurbished batteries costs 30 per cent less than an equivalent system using "fresh" cells. The environment and savings can go hand in hand.