The volatility of renewable energy sources, such as wind or sun, makes storage solutions indispensable for the success of the energy transition. Thanks to the high specific heat of water, hot-water storage tanks are a very effective and comparatively simple solution for storing heat. If they are sufficiently large, the existing concrete storage tanks can also store large amounts of energy. However, they can only be operated up to a water temperature of 95°C, which significantly limits their storage capacity.

The BMWi has therefore granted funding to five partners from industry and research for their collaborative project BeHeWaDS. Their aim will be to investigate the use of ultra-high performance concrete (UHPC) for particularly efficient hot-water tanks. These should be able to withstand temperatures of up to 200°C and pressures of up to 15.5 bar. With these properties, the stored energy could then also be used, for example, in industry and for steam generation. The distinguishing feature of these hot-water heat storage tanks is that are to be produced in an inexpensive and uncomplicated manner. More specifically, this project will be investigating the suitability of using UHPC as a material for such storage tanks, e.g. its behaviour at high temperatures and cyclic loads. If necessary, modification possibilities are to be sought in order to achieve the desired resistance. The next step will be for the project partners to create test tanks that are tested under realistic conditions. Finally, a larger-sized test tank with a volume of approx. 100 litres will be used to validate the results.

The BMWi is funding the collaborative project for a period of three years, from September 2018 to August 2021.