All over California, there's evidence of the state's goal to lead the country in renewable energy. Enormous farms of shiny solar panels have popped up across southern California, and gigantic wind turbines dot the landscape outside nearly all the major cities. There are less flashy—and less visible—investments in renewables going on, too. Tucked away in warehouses, trailers and industrial parks are lithium ion batteries that, if all goes well, will play a critical role in helping California hit its ambitious target: to have 50% of all electricity come from renewables by 2050.
Some green energy sources come with a built-in challenge: the wind and the sun can't be turned on and off at will. When it's windy and sunny, an abundance of energy may be harnessed—but any excesses go to waste. That's where batteries, the most common type of energy storage, come in. Batteries solve that problem by allowing utility companies to collect excess electricity and store it for times when the sun may not be shining or the wind not blowing.