Borehole Thermal Energy Storage (BTES)

Besides sorption-based storage with its benefits of lossless long-term storage and compact size, sensible long-term thermal energy storage is also being researched. Of particular interest is thereby thermal energy storage in the soil using ground heat exchangers. In contrast to most borehole fields found in Switzerland we investigate in storage of thermal energy at higher temperatures (35-50°C) for more effective seasonal load shifting aiming at breaking the peak loads in winter and hence improving the over-all greenhouse gas emission balance rather than the energy balance.  

High temperature charging is achieved by using the waste heat from electrically driven cooling machines or from solar thermal collectors directly. The research project LeSoPot, funded by the SFOE, is assessing the potential of such a high-temperature borehole thermal energy storage along with integration of different renewable energy and waste heat sources. 

Figure 1: a) BTES hydraulic topology b) Thermal gradient established in the ground (vertical section) after being charged


Selected publications

Weber, R.  and Baldini, L. (2018). High Temperature Seasonal BTES for Effective Load Shifting and CO2 Emission Reduction. EuroSun2018 – 12th International Conference on Solar Energy for Buildings and Industry, September 10-13, 2018, Rapperswil, Switzerland.