The idea, known as "vehicle-to-grid", is to have millions of drivers become mini electricity traders, charging up when rates are cheap and pumping energy back into the grid during peak hours or when the sun is not shining. We need storage to make better use of wind and solar power, and electric cars could provide it. Today, fewer than 1 per cent of the world's vehicles are electric, but by 2040 more than half of all new cars will be electric. The first company to offer a product that allows drivers to both buy and sell power is San Diego-based Nuvve, which has succeeded by focusing on business customers in Denmark. www.inkl.com/newsletters/morning-edition/news/cities-running-on-car-batteries-idea-so-crazy-it-might-just-work?