From geology to site decision: Potential for underground heat storage in Graz

A promising solution for long-term thermal energy storage, cavern thermal energy storage (CTES), has been identified as feasible for Graz, Austria. This study highlights the potential of CTES systems to store excess heat from industrial processes, thereby contributing to CO2 emission reduction. Geological analyses pinpointed solid rock formations, particularly carbonates and crystalline rocks in the western and north-western areas of Graz, as suitable storage sites. Among these, the Karolinensteinbruch site was recommended due to its favorable geological conditions despite challenges such as distance to district heating networks and risks associated with karst phenomena. The conceptual designs proposed modular and expandable geometries to adapt to Graz's fluctuating urban energy demand. While the study confirms CTES as a viable option for Graz, it emphasizes the need for further detailed investigations into geotechnical and geological properties to ensure successful implementation.

Kaml, G., Schreilechner, M. G., & Marcher, T. (2025). From geology to site decision: Potential for underground heat storage in Graz. Geomechanics and Tunnelling, 18(1), 57–63. Portico. https://doi.org/10.1002/geot.202400080