Until electric cars evolve beyond the need for gigantic battery packs, we're going to end up lots of batteries that have reached the end of their lifespan. This doesn't mean that all those batteries are destined for the scrap heap, though, and GM has some creative ideas on how to reuse them.
Most electric car battery systems come with eight year warranties, because the batteries gradually lose capacity until they're not useful anymore. You probably notice the same thing with your laptop: its battery might have started out letting you play games for three hours, but after a few years, you're lucky if you can edit a text file for ten minutes.
As more and more new electric vehicles enter the market, more and more old electric vehicles are going to get pushed out, and companies like GM and Nissan are putting some serious thought into what to do with those once shiny and expensive battery packs. Pulling them apart and recycling the components is one option, but GM thinks it has a better idea: by wiring an old Volt battery pack into your house, GM says the battery could provide you with a respectable six hours of power during an outage.
For its part, Nissan wants to start bundling their Leaf batteries with solar panels, allowing you to store up power for home use or to charge your (new) electric car without having to rely on the grid. Alternatively, you can use your new house battery to store up grid power during the middle of the night when it's cheap, and then use it up during the day to save you money on your electric bill every month.
What we're essentially talking about here is a giant uninterruptable power supply for your house that you can use in any number of ways, all of which have the potential to save you headaches during power outages and money the rest of the time, while also providing a new home for sad and lonely battery packs that have been discarded by their previous owners who didn't think they were good for anything anymore. It's a great idea, and at this point, it's just up to GM and Nissan to make it, you know, happen.