Seismic Risk Mitigation for Geothermal Projects in Densely Populated Areas: Lessons from the Haute-Sorne Pilot Project

As the global energy transition accelerates, Geothermal Systems are increasingly recognized for their potential to provide baseload renewable power and heat. However, the deployment of geothermal projects near urban centers faces significant challenges related to induced seismicity, as evidenced by discontinued projects in Basel and St. Gallen. This presentation details the comprehensive seismic risk mitigation strategy developed for the Haute-Sorne EGS pilot project in Switzerland and discusses its critical relevance for future geothermal deployment in densely populated settings.

The Haute-Sorne project employs a multi-faceted approach to risk management that surpasses the current state of the art. Central to this strategy is a shift from single, large-scale stimulations to a multi-stage stimulation concept. By dividing the reservoir into smaller, engineered segments, the project aims to limit the maximum magnitude of induced events, a crucial prerequisite for operating in urban environments where tolerance for felt vibrations is minimal.

To further ensure safety in sensitive locations, the project integrates Adaptive Traffic Light Systems (ATLS). Unlike conventional reactive systems, ATLS utilizes real-time data and earthquake forecasting to predict the evolution of seismicity based on planned injection schedules. This proactive capability allows operators to adjust or halt operations before adverse events occur, providing the high level of operational control necessary for city-based projects.

Finally, addressing social acceptance in populated areas requires transparent risk communication. We present results from a probabilistic risk assessment comparing the geothermal project's risk profile to accepted community risks, such as fire. This comparison demonstrates that with rigorous mitigation, EGS risks can be managed to levels comparable to everyday urban hazards. These lessons from Haute-Sorne provide a vital blueprint for the safe, socially acceptable integration of geothermal energy into the urban landscape.