Coal-mine companies in the U.S. and Germany are trying to turn their old mines into enormous power-storage systems, using century-old technology to keep the lights when a shortage of wind or sun makes new technologies inadequate.
WSJ.com: US Business, Wall Street Journal: Business
Thu, 05/25/2017 - 5:32am
Coal-mine companies in the U.S. and Germany are trying to turn their old mines into enormous power-storage systems, using century-old technology to keep the lights when a shortage of wind or sun makes new technologies inadequate.