Backfill materials play a decisive role in the performance and safety of geothermal probes. The NanoGeoTherm network is conducting intensive research into optimising this important component of geothermal systems.

Backfill materials in geothermal energy fulfil two essential functions: They prevent vertical groundwater flow between different groundwater horizons and thus ensure groundwater protection. At the same time, they ensure good heat conduction between the pipe wall of the geothermal probe and the surrounding rock, which is crucial for the efficiency of the geothermal system.

Backfill materials must fulfil various requirements:

• High thermal conductivity for efficient heat transfer
• Hydraulic integrity to protect the groundwater
• Resistance to freeze-thaw cycles
• Good workability on the construction site

Outlook

The optimisation of backfill materials makes a significant contribution to further increase the efficiency and safety of geothermal systems. The network NanoGeoTherm is committed to the continuous further development of this key technology in order to fully utilise the potential of near-surface geothermal energy.