Digging to very great depths worries many. With its new approach, the company SwissDGS intends to restore the reputation of a source of energy that is contested despite its strong potential.
It only takes a few minutes on a videoconference to understand his enthusiasm. Co-founder of the company EAPOSYS, Patrick Scherrer announced this Wednesday, November 13, the creation of SwissDGS: a new joint venture between the young Swiss company and the groups Amberg and Basler & Hoffman. "It is a key step for the future of deep geothermal in Switzerland for sure, but also in the rest of the world in the longer term," the entrepreneur says.
With SwissDGS, the objective is clear: to accelerate the deployment of deep geothermal in Switzerland through an approach presented as revolutionary and providential for the whole sector. Under the acronym AGS (for "Advanced Geothermal Systems"), the method developed by EAPOSYS differs from the one currently used: EGS systems (for "Enhanced Geothermal Systems").
But before presenting this new technology in more detail, it is necessary to take a quick step back to recall how current EGS solutions work and exploit heat from great depths (between 4 and 5 km deep). They are inspired by techniques used by the oil industry in the exploitation of shale gas. In the field, people speak of "fracking" or hydraulic fracturing.
Even though the hydro-shearing techniques used for deep geothermal are different from those of oil fracking, the concept remains to inject water under pressure underground to make it travel through fractures to absorb heat and then be pushed back to the surface. The heat of the water is then converted into electricity using a steam turbine or a binary power plant system. Once cooled, the water is reinjected into the ground to repeat the process.
However, this method poses a major problem: a danger of induced seismicity. In Switzerland, the most famous project is the unfinished Basel project (between 2006 and 2009). Built on a known seismic fault, the infrastructure was the source of earthquakes felt by the local population as well as damage estimated at several million francs.
"Our country has a very large geothermal potential. The prospects offered by this source of clean, inexhaustible and permanent energy are attractive," says the Federal Office of Energy.
This first experience explains the many reservations among the population such as those ongoing in the Jura with the Haute-Sorne project. Supported by the Confederation as part of its 2050 energy strategy, this plant built and operated by Geo-Energie Suisse will operate using an EGS technique.
Even though EGS systems have made enormous progress since the Basel experience — fracturing is now done in stages along sections of deviated boreholes and under permanent seismic monitoring — the most effective solution to reassure minds would be to move to a more advanced method, a method that does without fracking.
This approach is the one advocated by SwissDGS for its future installations (called EAPOLABs). "These are AGS systems consisting of collecting heat simply by circulating water in deep deviated wells that are connected to each other at depth, like an inverted radiator. There is therefore no overpressurization of the medium, which removes the risk of inducing earthquakes," explains Naomi Vouillamoz, CEO and co-founder of EAPOSYS.
A slight caveat: "Since heat exchange now occurs only by conduction, a slower process than advection, AGS require deploying several tens of kilometers of deep deviated wells to allow electricity and heat production equivalent to a conventional EGS," admits Naomi Vouillamoz. She nevertheless recalls that "heat demand represents 50% of our energy consumption and that AGS-type deep geothermal could easily cover 30% of it with installations totaling only a few kilometers of deep wells."
The AGS approach has another strong argument: its potential for standardization. While deep geothermal must contend with a heterogeneous subsurface and geochemistry, the closed-loop approach is predictable and requires less maintenance cost. While the Geo-Energie Suisse power plant project was budgeted at 130 million, SwissDGS mentions a price range of 25 to 50 million francs for an EAPOLAB.
At a time considered critical for the planet, the opportunity to use the heat available in the depths of the Earth now appears unavoidable. In the United States as well as on the Old Continent, experiments are multiplying. In Switzerland, the Federal Office of Energy also seems convinced. "Our country has a very large geothermal potential. The prospects offered by this source of clean, inexhaustible and permanent energy are attractive: free of CO2, it provides local energy 24/7, 365 days a year without taking up space."
"The potential of so-called unconventional deep geothermal (EGS and AGS) is enormous, insofar as the vast majority of the heat beneath our feet is found in the rock (99% of accessible heat) compared to 1% in conventional resources," explains Naomi Vouillamoz.
According to Patrick Scherrer, starting to use this source of energy and heat would make it possible to make up for the flaws of the energy transition as currently envisioned. "Whether it is the move to 100% electric mobility or the use of only renewable energies such as solar or wind, these solutions will exhaust all of the planet's mineral resources. This path is therefore absolutely not sustainable," says the entrepreneur, citing a report by Lazard dating from May 2023.
"Whether it is the move to 100% electric mobility or the use of only renewable energies such as solar or wind, these solutions will exhaust all of the planet's mineral resources," explains Patrick Scherrer, co-founder of EAPOSYS
And in a particularly tense geopolitical context, deep geothermal has another advantage: welcome energy sovereignty for states. "The political world is finally realizing that geothermal will be part of the solution, a complement to the energy mix that humanity will need," explains Jon Mengiardi, the man entrusted with the reins of SwissDGS.
In the coming months, he will have the task of finding a site to install a very first EAPOLAB, then convincing the authorities and the whole country of the merits of their solution on a larger scale. "The timing is ideal," the founders of SwissDGS believe. Time will tell whether Switzerland will manage to overcome the first traumas of Basel.
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