The availability of powerful thermal energy storages is an essential precondition for a successful energy transition. Due to the big share in the total energy consumption the focus is on (1) a cost-efficient, safe and widespread useable storage to provide room heating and domestic water. Besides there is a great interest in (2) high-temperature storages for the application in solar thermal power plants and reactors. An innovative interaction of materials development, control systems and the combination of different technologies seems to be the most promising strategy.