Zurich Project Explores Storing CO2 Beneath Switzerland

(MENAFN- Swissinfo) In 15-20 years, carbon dioxide (CO2) from Swiss household waste and industry could be stored underground to support the country's net-zero climate goals. Scientists hope a pilot project near Zurich can clarify the ideal strategy: whether to store the carbon in Switzerland or pump it beneath the North Sea. This content was published on April 15, 2025 - 09:00 11 minutes

I am a climate and science/technology reporter. I am interested in the effects of climate change on everyday life and scientific solutions. Born in London, I am a dual citizen of Switzerland and the UK. After studying modern languages and translation, I trained as a journalist and joined swissinfo in 2006. My working languages are English, German, French and Spanish.

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Set amid rolling green hills and vineyards 30 minutes north of Zurich, Trüllikon is a sleepy village which, on the surface, seems to be of limited interest.

It has a post office, two restaurants and a supermarket, but it also has a deep disused borehole of national importance, which offers insights into the underground environment and its potential as a geological repository.

Since last autumn, scientists from the federal technology institute ETH Zurich have been studyingExternal link the feasibility of storing CO2 underground there.

The researchers are taking seismic measurements deep below the surface. That data goes into computer modelling that estimates the storage capacity and risks. If they get the go-ahead, small quantities of CO2 could be injected into the site starting mid-2026.

A cross-section of the geological situation below Trüllikon, near Zurich, and the CO2 test injection process. ETH Zurich

But Trüllikon is only a test, insists Michèle Marti, a scientist at the Swiss Seismological Service at ETH Zurich, who oversees communication for the scheme.

“It is not intended to become a permanent storage site. After this test, we would close the borehole and there would be no further CO2 injected there,” she explains.

Despite its temporary nature, the Trüllikon project is key to shaping Switzerland's step-by-step carbon capture and storage (CCS) strategy. Scientists will examine the viability of storing CO2 under Swiss territory and gain valuable data on quantities and costs that will guide decisions on long-term CO2 storage, both domestically and abroad.

“The main question right now is: should we store CO2 in Switzerland or outside,” says Cyril BrunnerExternal link , a senior climate scientist at ETH Zurich.“This is why this Trüllikon test is so important. This pilot will help define how much it would cost to store it in Switzerland and what the other trade-offs are.”

Technologies are needed to capture or remove CO2 and store it permanently. Carbon capture and storage (CCS) captures and stores fossil and process-based CO2 at installations such as waste treatment plants to cut emissions, while negative emission technologies (NETs) focus on permanently removing CO2 from the atmosphere.

NETs include, among others: afforestation and reforestation; land management to increase and fix carbon in soils via additives such as biochar; bioenergy production with carbon capture and storage (BECCS); enhanced weathering; direct capture of CO2 from ambient air with CO2 storage (DACCS), ocean fertilisation to increase CO2.

According to the Intergovernmental Panel on Climate Change (IPCC), achieving the goals of the Paris Agreement will require a very rapid global expansion of CCS and NETs, in addition to a substantial reduction in greenhouse gas emissions.

While CCS is recognised by the Intergovernmental Panel on Climate Change (IPCC) as crucial for climate goals, critics such as Greenpeace callExternal link it expensive and risky, potentially prolonging fossil fuel use.

Still, the Swiss government sees the technology as essential to reaching its 2050 net-zero target. By then, seven million tonnes of CO2 captured from waste plants and cement work could be captured and storedExternal link annually.

Switzerland's 'hard-to-abate' carbon emissions can be offset with carbon capture and storage (CCS) and negative emissions technologies (NETs). CCS captures and stores fossil and process-based CO2 at installations like waste treatment plants to cut emissions, while NETs focus on permanently removing CO2 from the atmosphere. FOEN

But key questions remain. Is storage under Swiss soil cost-effective? What are the risks? Could the idea face resistance, like that faced by geothermal or wind energy projects? How much Swiss CO2 might be exported to countries such as Norway or the Netherlands?

Underground – what actually happens to the CO2

Geology is central to CCS feasibility. Switzerland has certain rock types – basalt, peridotite and serpentinite – in the southern Alps that would be suitable for in-situ mineralisation, the process whereby CO2 dissolved in water and pumped underground as carbonic acid penetrates and dissolves porous rock, releasing iron, magnesium and calcium ions. The CO2 combines with calcium and magnesium to form white carbonate rock, for example limestone. But due to the complex structures under the Alps, high water demands and economic hurdles, this particular CCS technique is not a viable option on Swiss territory, research showsExternal link .

But researchersExternal link have found an alternative: areas in Switzerland's central plateau region with sedimentary rock and saline aquifers suitable for long-term CO2 storage.

Trüllikon's deep borehole – originally drilled to study the possibilities of storing nuclear waste underground, but not used – offers ideal test conditions.

“In Switzerland there aren't that many boreholes that go so deep – over 1km. It's really in good condition and suitable for doing such a pilot injection with the right geological conditions. If you had to drill such a borehole, it would be very costly,” Marti explains.

The plan involves injecting liquefied CO2 into a porous rock layer, capped by impermeable Opalinus clay to prevent leaks. The liquefied CO2 would spread several hundred metres around the hole in the seam. Over time it would slowly mix and sink to bottom of the layer and dissolve into salty groundwater hundreds of metres below drinking water layers, with minimal leakage risk.

Potential CO2 storage sites in Europe, according to data from the EU-funded CO2StoP project from 2013. Source: JRC, 2024 How many boreholes are needed?

“The thing we want to figure out in Trüllikon is how many holes you would need to drill in order to store a certain amount of CO2 per year,” Brunner says.“We don't know whether the porosity of the rock – how much CO2 can diffuse through the rock – is sufficient to require one borehole for one million tonnes of CO2 for instance. Would you need one borehole per waste incineration plant, for instance, or one for ten plants?”

Early government estimates suggested five Swiss storage sites may be needed.

According to a 2023 government-commissioned studyExternal link , building a Swiss CCS system from 2028 to 2050 would cost CHF16.3 billion ($19.3 billion), with CHF1-2 billion in annual operating costs. More than half the cost would go towards CO2 capture infrastructure, while pipeline construction would account for 30%. However, experts warn that these figures are highly uncertain.

The Federal Office for the Environment (FOEN) believes that piping CO2 abroad or storing it in Switzerland would likely carry the same costs in the long run.

Iceland and Norway are at the forefront of developing innovative CCS technologies. In Norway, more than 19 million tonnes of CO2 have been stored under the North Sea since 1996. Denmark has also issued six licences for the exploration of CO2 storage facilities. As part of the Greensand project, 1.5 million tonnes of CO2 per year are to be stored in the seabed from 2025/2026 and eight million tonnes from 2030. The country's GreenstoreExternal link project was also the first licence granted for underground CO2 storage on land.

In the Netherlands work is underway in the port of Rotterdam to construct pipelines and compression stations to store CO2 off the coast. The project could go into operation in 2026.

France, Germany, Sweden, Poland, Austria and Croatia are also developing CCS strategies. Denmark, Belgium, the Netherlands and Sweden have also established arrangements for cross-border transport and storage of CO2 with Norway. Sweden and Denmark have concluded similar arrangements.

Transporting CO2 – pipelines

There are now nearly 200 potential CCS projects in Europe. Today, most underground CO2 storage sites are being developed in the North Sea, which offers significant potential thanks to sandstone formations.

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But deploying the technology is highly complex, with many technical, economic, environmental and regulatory challenges. A 2024 Institute for Energy Economics and Financial Analysis (IEEFA) report warnsExternal link most projects are overambitious, with many far from commercial viability.

Transport remains a major hurdle. Moving CO2 by road, rail, ship or pipeline adds complexity and cost. A recent European Commission studyExternal link highlights the need for a robust cross-border CCS transport network and strong international cooperation.

Potential CO2 transport network in 2050, according to European Commission study published in 2024. Source: JRC, 2024

Pipelines, especially for inland countries such as Switzerland, are seen as the most cost-effective solution.

A consortium is being formed to build a Swiss pipeline network, Dominik Wlodarczak, CEO of CO2 Pipeline Schweiz AGExternal link , told SWI swissinfo. A first section to transport CO2 from Zurich to Basel could be operational by the mid-2030s. But there is still much uncertainty, as the new venture must coordinate with a European network and link up at the Swiss border via either France or Germany.

“We expect all captured CO2 will be exported to the North Sea, with maybe smaller amounts to the Mediterranean,” Wlodarczak says

Getting the public on board

Amid the myriad challenges, public acceptance of CCS and environmental concerns must also be carefully considered.

Between 2022 and 2024, researchers from ETH Zurich carried out a pilot projectExternal link to investigate the potential of transporting and permanently storing Swiss CO2 abroad – in this case in Iceland.

More More Turning Swiss CO2 into Icelandic rock

This content was published on May 28, 2024 Efforts to capture carbon dioxide from dirty industries and store it deep underground are generating huge interest globally. Switzerland is also examining what to do about its hard-to-tackle CO2 emissions.

Read more: Turning Swiss CO2 into Icelandic roc

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