The Stadtwerke Stuttgart GmbH (SWS) is currently planning to supply a major infrastructure project in the Stuttgart-Hausen area with renewable heating and cooling. Part of the excavated soil resulting from the construction work will be piled up in the south of the site to form a mound for reasons of nature conservation and immission control. This earthwork structure, comprising approx. 18,000 m³, is to be equipped with ground-heat-collectors in several layers as an environmental heat source (and sink).
Heat pumps extract heat from the collector in winter, causing the ground to freeze. In summer, the stored cold is to be used to meet cooling requirements. Alternative heat sources are also available for thermal regeneration of the collector. Such multi-layer geothermal collectors can also be referred to as "ground ice storage" in reference to a research project of the same name by Stadtwerke Schleswig.
The presentation summarizes and discusses the results of extensive thermal simulations on the expected energy potential of the structure. The aim of the investigation was, to determine the expected charging and discharging capacities and the seasonal storage capacity of the structure. Furthermore, various methods for the thermal activation of the ground were investigated, as well as the spread of ice formation in the ground and the suitability for short- and/or medium-term load shifting.
In terms of future prospects, the potential economic efficiency of this system is discussed, e.g. in comparison to earth basin heat storage systems or single-layer ground-heat-collectors, as well as the relevant boundary conditions.