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Subproject 3.4

Backfill material quality check for BHEs under real conditions

Lead Management
Hauri KG / Solites
Subproject Leader
B. Sc. Alexander Kugler (
M.Sc. Yannick Reduth (
Participating Partners
Hauri KG
Burkhardt GmbH
Fraunhofer ISE
ZAE Bayern

In this subproject, up to 8 borehole heat exchangers are constructed in a quarry of the Hauri company in cooperation with Hauri KG and Burkhardt GmbH according to the current state of the art. Subsequently, these borehole heat exchangers are exposed from the subsurface and completely analysed. These kind of quality investigations are done for the first time for borehole heat exchangers to this extent. In addition to the scientific findings, the results can also help to vividly demonstrate the reliability of the current technology and thus increase the acceptance and approval of shallow geothermal energy among the population. The main focus of these investigations of the exposed boreholes is on the transferability to reality of the findings of the investigations carried out on the backfilling quality in the previous projects EWSplus [Riegger, 2013], EWS-tech [Riegger et al., 2016], EWS-tech II [Riegger et al., 2020] and QEWS II [Fuchs et al., 2020]. On the one hand, this concerns the filtration behaviour of the backfill materials, which depends decisively on the contact between the suspension and the surrounding formation. In addition, the influence of various backfilling materials and drilling diameters on the formation of faults and the concatenation of the backfilling material to the unconsolidated rock is investigated. Furthermore, the possibility of visual observation of the exposed borehole heat exchangers allows to directly evaluate the measurement results of the developed measurement systems for the investigation of the backfilling quality. The following procedure is planned:

[Riegger, 2013] Riegger, M. (2013): EWSplus - Untersuchungen zur Qualitätssicherung von Erdwärmesonden (Weiterentwicklung der Erdwärmesonden-Technik), final report of the research project EWSplus, Solites, Stuttgart
[Riegger et al., 2016] Riegger, M., Rolker, J., Steger, H., Stober, I., Haist, M., Eckhardt, J.-D., Schlager, P., Zemann, M., Zorn, R., Huttenloch, P. (2016): EWS-tech: Weiterentwicklung der Erdwärmesonden-Technologie, final report of the research project EWS-tech, grant number L75 13004 until L75 13007, Solites, Stuttgart
[Riegger et al., 2020] Riegger, M., et. al. (2020): EWS-tech II: Entwicklung überprüfbarer Kriterien für Erdwärmesonden-Verfüllungen unter realitätsnahen Randbedingungen, final report of the research project EWS-tech II, grant number L75 16008 until L75 16011, Solites, Stuttgart
[Fuchs et al., 2020] Fuchs, H., Hagel, K., Karrer, H., Kuckelkorn, J., Lutz, T., Schindler, L. (2020): QEWS II- Untersuchungen zur Bohrlochverfüllung und Abdichtung von Erdwärmesonden-Bohrungen, Geothermische Energie, 2/ 2020: p. 14-19
Project Partners
Funding Authority