By 2038, Germany will have phased out its lignite mining industry, which is concentrated in the central states of Thuringia, Saxony and Saxony-Anhalt. The decarbonisation of the country’s energy supply presents an enormous challenge: the deficit resulting from the loss coal-fired plants will have to be made up from renewable sources.

The SEETHERMIE project is a future-focused initiative funded by the three states together with the federal government, that will investigate the general energetic potential of opencast mining lakes and water bodies in the "Innovation Region Central Germany.” It will focus initially on Lake Zwenkau in Lusatia which was created by the flooding of a vast opencast mining area. The technical suitability of thermal lake water for powering local heating networks will be explored, alongside economic viability and environmental concerns.

A highly innovative vacuum-liquid ice technology which was developed by the Institut für Luft- und Kältetechnik GmbH Dresden (ILK Dresden), will be employed for this purpose. Through the evaporation of single water molecules at the water surface, energy is detracted from the surrounding liquid. Because evaporation takes place in a vacuum-sealed tank at the triple point of about -0.5 °C, other water molecules freeze and form ice particles. The ice slurry is generated in turbo compressors for storing cold (for use in refrigeration and air conditioning) and caching energy (Power-to-cold). Compared to conventional heat pump systems, this process is highly energy-efficient and sustainable.

The project will be led by the geoscientific consultancy JENA-GEOS® and involves several partners including ILK Dresden, Institut für Wasser und Boden Dr. Uhlmann (IWB Dresden), Tilia GmbH, Technische Beratung für Systemtechnik Bernd Felgentreff and the Brandenburg University of Technology Cottbus.