Impact of high-temperature heat storage on groundwater
In a recently launched project, the aquatic research institute Eawag is investigating how the use of borehole thermal energy storage (BTES) affects the surrounding soil, the groundwater and the microorganisms living in it. In collaboration with Empa and its Demonstrator Energy Hub (ehub), a project is being developed in a unique setting on the campus in Dübendorf.
In winter, conventional geothermal heat pumps draw heat from the ground to heat buildings. The borehole heat accumulators installed on the Empa and Eawag site are geothermal probes that can not only draw heat to the surface in winter, but also store the heat from the summer months in the ground so that it is available in the colder months of the year. The maximum temperature that can be fed into the reservoir is 65 degrees Celsius – a record in Switzerland and therefore unique in the country. As a result, temperatures of up to 50 degrees Celsius can be reached locally in the ground on average.
So far, however, little is known about how the subsurface reacts to these high-temperature reservoirs. The regular heating and cooling of the probes at depths of up to 100 metres can affect the chemical components in the groundwater as well as the microbial communities in the soil and water. Exactly how and to what extent is now being investigated as part of the ARTS (Aquifer Reaction to Thermal Storage) research project at the aquatic research institute Eawag.
Read more in the Eawag news release.