It's a well known fact that lithium ion batteries degrade over time, and there are some EV naysayers that love to point this out whenever the topic of electric car batteries comes up. It's true, eventually there will be a point where those batteries won't be all that useful for driving - for a variety of reasons. But those old batteries aren't scrapped, they're put to use elsewhere. Nissan's been connecting old batteries to solar panels and installing them in homes, and a bunch of BMW i3 batteries have just been installed at a Welsh wind farm.
Swedish power company Vattenfall has installed 500 old i3 batteries at the Pen y Cymoedd Wind Farm, making it one of the largest co-located installations in the UK. The idea being that storing the power on site will help the National Grid manage frequency levels and offer a more reliable supply of electricity. The batteries each have a 35kWh capacity, and live inside five shipping containers on the site. Pen y Cymoedd itself has a generation capacity of 22MW, which is enough to power around 140,000 homes.
As Electrek points out, 500 batteries isn't a particularly small number. BMW delivered 500 i3 vehicles to the US last month, so there's significant portion of the company's battery manufacturing resources being used for something other than cars. Not every battery will be brand new, but it does mean car manufacturers can diversify that area of their business and not necessarily have to rely on singificant EV sales. It also means they have something to do with the old batteries, once EVs are retired or need a replacement. [Vattenfall via Electrek, Engadget]