Deep geothermal energy research

Werner Siemens Foundation Endowed Chair Martin O. Saar and his team at ETH Zurich have developed an innovative method for tapping into the energy in the earth’s crust and simultaneously capturing the greenhouse gas carbon dioxide. What’s more, the procedure will work in Switzerland’s extremely hard subsurface as well as in other geologically difficult areas.

In his research, Werner Siemens Foundation Endowed Chair Martin O. Saar wants to find ways to harness the earth’s heat and use it to generate electricity in geothermal power plants. In Switzerland, the past few years have seen a major increase in federal funds invested in deep geothermal energy, which is being discussed as an alternative energy source for after the phase-out of atomic power and fossil-fuel energy production.

Although generating electricity from deep geothermal energy isn’t feasible in Switzerland, the situation is different in Germany, while the US is a global leader in geothermal power plants. Different geological conditions are the reason. Switzerland lacks the high subterranean temperatures near the earth’s surface that are easier to tap into, and the volatile seismic activity of Iceland or California that keeps the subsurface porous for heat transfer isn’t a characteristic of the hard granite in Alpine areas. Indeed, in Switzerland and most other areas of the world, it’s much more difficult to access the earth’s heat and then convert it into electricity. This is where Martin O. Saar’s research comes in: he wants to make cost-effective geothermal power production possible in previously inaccessible areas.

In a first step, Martin O. Saar and his team conducted computer simulations, lab experiments and field research in the rock layers in order to study how geofluids make their way through hard rock like granite and to better understand how geothermal energy flows “move” in the earth’s crust. The team came upon the idea of using carbon dioxide to transport heat a few years ago – and it’s proven to be a major coup. Not only is CO₂ an ideal fluid for accessing geothermal heat at many different geological sites, but permanently storing the greenhouse gas underground is also a way of reducing carbon dioxide levels in the atmosphere.

The project and its innovative approach has met with success, with numerous patents, international partnerships and spin-off companies having already resulted from the work. A novel electropulse drill was also developed in collaboration with geothermal power plant builder SwissGeoPower and then successfully tested. In 2021, Saar received an Innosuisse Grant from the Swiss Innovation Agency, which he will use to optimise the highly promising electropulse drilling technology.