"The end of coal-fired power generation and nuclear energy simply makes such storage systems inevitable." That is because electricity generation from renewable sources is subject not only to seasonal fluctuations, but also to those between day and night. At present, periods of low electricity production are still bridged by conventional power plants. If these are taken off the grid in the coming years, other solutions will have to be found. For periods of several months, long-term storage systems based on hydrogen or methane produced from renewable sources are an option. However, short-term storage systems based on battery technology are more suitable for bridging the night. In order for an industrialized nation like Germany to succeed in taking the step toward regenerative energy supply, reliable and cost-effective storage systems for large amounts of energy are needed. An international team led by Tom Weier and Norbert Weber from the Institute of Fluid Dynamics at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) has set itself the task of bringing these systems to application maturity. In the SOLSTICE project, they want to develop electricity storage systems based on liquid sodium and liquid zinc starting in January 2021. The European Union is funding the project with eight million euros through the Horizon 2020 program.