Batteries are everywhere these days: in our iPhones, toothbrushes, vacuum cleaners, and electric cars. But batteries—really big batteries—are just getting started.
The idea is that grid-sized versions might be used to store excess wind and solar power, smoothing out the peaks and valleys of the electricity supply. There’s just one problem: Batteries are still way too expensive when stacked up against cheap coal and natural gas. Today, less than one-tenth of one percent of the world’s electricity spends any time in a storage battery.