Grid -- Below-Ground Balancing (IMAGE) DOE/Oak Ridge National Laboratory Caption ORNL researchers have developed a system that stores electricity as thermal energy in underground tanks, allowing homeowners to reduce their electricity purchases during peak periods while helping balance the power grid. Credit Andy Sproles/Oak Ridge National Laboratory, US Dept. of Energy Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.