Graphic of the Technology (IMAGE) Graz University of Technology Caption Combined energy storage systems are the key technology for the future of global energy supply. Credit © Pikl - TU Graz Usage Restrictions Free by mentioning the right Caption/Credit 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.