Mercedes and Tesla aren't the only electric car makers giving their batteries something to do besides getting you from A to B. Nissan is teaming up with Green Charge Networks to repurpose "second-life" (read: used) batteries from Leaf EVs as commercial energy storage. Much like the batteries you can buy for your home, the lithium-ion packs will help offices save money (and ideally, the environment) by storing cheap energy. Companies can charge up overnight to avoid painful peak electricity rates, for instance, or reserve power from solar and wind farms that would otherwise go to waste. The Leaf-based tech will see its first use at one of Nissan's own facilities this summer, but we'd expect it to spread to other businesses in short order.