With the implementation of the Energy Strategy 2050, the demand for seasonal storage of electricity increases. One option is to extend existing reservoirs of storage hydropower plants by heightening their dams. Researchers from the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at ETH Zurich evaluated the possibilities and potential benefits of heightening 38 dams in the Swiss Alps. They concluded: If 17 to 26 dams were heightened by up to 20 %, a total of 2.2 to 2.9 TWh of electric energy per year could be additionally shifted from summer to winter. This corresponds to the household electricity consumption of 1.7 to 2.2 million inhabitants during winter.