Spallation drilling – a technology to boost the geothermal energy supply of Switzerland

In a geothermal power plant the drilling process accounts for about 60% of the total investment cost. Spallation drilling is a novel contact-free drilling technology with the potential to considerably reduce drilling costs and thus enhance the development of geothermal energy production. The technology is based on hard rocks disintegrating into small fragments when rapidly heated by a hot flame jet. Previous research has indicated that spallation drilling could decrease drilling costs by achieving higher drilling velocities and by significantly reducing tripping and maintenance time.

At the Transport Processes and Reactions Laboratory (LTR) various spallation experiments, from small rock probes to large-scale granite blocks, are performed in different experimental facilities. These setups create intensive flame jets, including flames under water at pressures above 250 bar. Michael Kant, member of the research group of Prof. Rudolf von Rohr, has proven the feasibility of spallation drilling as a standalone technology, as well as in combination with mechanical drilling. From the experimental studies he could draw conclusions on the feasibility, benefits and limitations of the technology. In a next step field tests will be performed to further develop the process and to prove the operational readiness of the technology.