Energy storage is critical for the growth of renewables because, simply put, the wind doesn’t blow all the time and the sun doesn’t always shine. Something unexpected is happening in India. Utilities that used to sign 25-year contracts to purchase coal-based electricity are beginning to get nervous. They’re still buying the dirty power. The difference now is that they won’t get locked into a contract longer than 10 years, believing that energy storage combined with inexpensive solar and wind power will soon become more economical than the coal-fired equivalent.