Validation of thermal groundwater use

Ramona Nüssli, 19. August 2022

Applications of thermal groundwater models for the evaluation of the impact of heat pumps.

Model mesh (grey), Extraction well (green), Injection well (pink), Temperature difference > 1 K (red), Groundwater level (blue)

Groundwater plays a central role in Switzerland's drinking water supply. In recent years, however, groundwater has also become increasingly important for energy production.

TK CONSULT AG has carried out various numerical investigations in this context.

Basis for the realization of heat pumps is the FOEN implementation guideline for heat utilization from soil and underground. It mentions a maximum allowed temperature change of 3 °C compared to the natural state by heat input or heat extraction. In the immediate vicinity of a maximum of 100 meters, this change may be more than 3 °C.

To evaluate the thermal impact, a 3D hydrothermal groundwater model is used to calculate both the situation without and with thermal use. Typically, the calculation period is 10 years, because experience shows that a temperature equilibrium is reached after this time. From the results of the two calculations, the difference is formed to obtain the influence of the groundwater heat pump. On this basis, it can be shown whether the legal conditions can be met. If this is not the case, the model can be used to optimize usage to this end.

Temperature hydrograph at extraction well (blue) and injection well (red) without thermal use (light colors) and with thermal use (dark colors)

Contact person

Ramona Nüssli

Ramona Nüssli

MSc. Env. Eng. ETH

Project manager

Tel.: +41 (0) 44 288 81 85