What to do with the CO2? – Out of the atmosphere, into the underground – Knowledge


Global warming is progressing. What to do with the CO2? Underground storage is being tested in the Swiss Jura.

Deep in the mountain, researchers are currently investigating how the climate catastrophe can still be averted. In the Mont Terri rock laboratory near Saint-Ursanne in the Jura, they want to find out whether and how CO2, the fuel of climate change, can be safely stored underground in Switzerland.

Because more and more scientists agree that climate change can no longer be stopped by reducing CO2 emissions alone. The Intergovernmental Panel on Climate Change has already firmly planned the following scenario from 2050: Greenhouse gases have to be sucked out of the atmosphere and then bunkered several kilometers below ground – for example in an empty gas field or in a porous layer of rock with salt water.

Safe place urgently needed

Carbon Capture and Storage, or CCS for short, is what it is called in technical jargon. It is part of the so-called geoengineering, i.e. one of the technologies with which one wants to stop climate change beyond the energy transition and CO2 avoidance.

It is no coincidence that the researchers chose the Swisstopo rock laboratory in the canton of Jura. It is located in the middle of the so-called Opalinus Clay.

«The opaline suton is very dense. This means that the permeability for liquids and gases is very low,” says geophysicist Melchior Grab from ETH Zurich.

The Opalinus Clay would be an excellent cover rock to seal a CO2 repository at depth. And the researchers at Grab are now meticulously examining this cover.

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But how safe can “safe” be?

Because the geologists cannot rule out the possibility that a kilometer-long cover of rock does not have potential leaks somewhere, so-called fracture zones. The crucial question: Could liquid CO2 migrate through a fracture zone and thus escape from a possible repository?

Expert meeting in Switzerland

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Fishing the climate killer CO2 out of the atmosphere and bunkering it in deep repositories is the subject of this week (May 5th – 10th) at a big conference in Les Diablerets in Switzerland.

Experts from all over the world present new projects and technologies. For example the CarbFix project in Iceland. The scientists have succeeded in turning CO2 into stone in a short time.

Even the ambitious ones Norwegian plans are subject. They want to provide Europe with a gigantic CO2 repository in the seabed.

Les Diablerets will focus primarily on the challenge of being able to apply the technologies on the necessary large scale.

To clarify this, the researchers inject CO2 dissolved in salt water into the fracture zones via a borehole. If the liquid migrated, sensors would register it.

While basic research is still being carried out in Switzerland, Norway has been pumping CO2 into empty gas and oil fields under the seabed for some time.

Pilot projects in Germany failed a few years ago due to massive public protests. One of the fears was that the CO2 in the ground could trigger earthquakes.

better assess risks

“I think it’s extremely unlikely that a really big earthquake would be triggered at this depth given the amount of CO2,” says Stefan Wiemer, Director of the Swiss Seismological Service. The experiment in Mont Terri should now provide basic data for Switzerland in order to better assess the risk of CO2 storage underground and thus to be able to counter people’s fears with facts.

But for the deep CO2 repository itself, even a mini earthquake could be a problem. “Earthquakes always mean that something is moving underground,” says Melchior Grab. As a result, further fissures could open up in a fracture zone.

In the Mont Terri rock laboratory, the researchers therefore want to use water pressure to trigger mini-tremors and analyze what is happening. After that, data will be available for the first time to better assess the risk of CO2 storage in Switzerland.

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