Bedretto Underground Laboratory for Geosciences and Geoenergies
The BedrettoLab (Bedretto Underground Laboratory for Geosciences and Geoenergies) is a unique research infrastructure run by ETH Zurich making it possible to take a close look at the Earth’s interior. It is located in the Swiss Alps 1.5 kilometres below the surface and in the middle of a 5.2 kilometres long tunnel connecting the Ticino with the Furka railway tunnel.
Equipped with the latest technology, the BedrettoLab offers ideal conditions to conduct experimental research focusing on the behaviour of the deep underground when accessing and stimulating it. Such an access is required to advance scientific knowledge in various domains including geothermal energy and earthquake physics. It is also of relevance to develop novel techniques and sensors for these purposes.
2025-12-01
Second cycle of hot-water injection starting today
Today marks the start of the second cycle of hot-water injection into the granite reservoir at the BedrettoLab. This experiment builds directly on what we have observed in the first cycle.
The first cycle ended last week. It consisted of an injection phase of two weeks, a storing phase of 10 days, and the reopening of the borehole. The storing phase simulated a period during which the underground reservoir would rest before the stored heat is used. When we reopened the borehole, we examined how much heat remained in the water and the surrounding rock. As expected, much of the heat was either lost during the injection as the borehole is not thermally insulated or escaped by draining away from the reservoir. Despite this heat loss, measurements showed that the target part of the granite had warmed by about 10 °C.
In the upcoming second cycle, we will again inject and store hot water using the same temperatures and injection rates. However, we will not include a longer storing phase before using the stored heat to see the difference in the thermal balance. Because the borehole and the nearby rock are already warmer from the first cycle, we expect less heat to escape this time.
In a future experiment planned for 2026, we will insulate the borehole above the injection interval. This helps to minimise heat loss along its length during the injection of the hot water.
2025-10-28
Hot water injection experiment started
Today, the first injection with hot water began in the BedrettoLab’s geothermal reservoir. The experiment that is part of the BEACH project, aims to inject approximately 200 m3 liters of water over a period of ten days. The water used for the test is collected from the surrounding rock massif, heated to 80 °C in a boiler in the geothermal testbed, and then injected into the rock volume.
The goal of this experiment is to investigate how much heat can be stored in the crystalline rock and how much of this energy can be retrieved after a storage period of two weeks. The experiment is the first of two hot water injections tests.
During the injection, a low level of seismicity is expected and will be monitored closely by the seismology team. As an additional safety layer, a traffic light system regulates the experiment, and if the observed magnitude exceeds pre-defined thresholds, the experiment will be ended immediately and bleed-off initiated.