Swiss pilot project has tested CO2 storage
Published: Wednesday, Dec 6th 2023, 12:40
Updated At: Wednesday, Dec 6th 2023, 12:40
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Capturing and storing CO2 is feasible with a positive carbon footprint. This was demonstrated by a Swiss pilot project using two methods for CO2 storage that were implemented and tested in practice as part of the project. However, there are regulatory challenges.
The results of the "DemoUPCARMA" (Demonstration and UPscaling of CARbon dioxide MAnagement solutions for a net-zero Switzerland) project led by the Swiss Federal Institute of Technology in Zurich (ETH Zurich) were presented on Tuesday.
"We need these technologies," Reto Burkard from the Federal Office for the Environment emphasized to the media. The Swiss climate targets stipulate that Switzerland must emit no more CO2 by 2050. To achieve this, emissions that cannot be avoided must be removed from the atmosphere. For example, emissions from waste incineration plants or agriculture. The federal government's Energy Perspectives 2050+ assume that 12 million tons of CO2 will be produced each year, which are considered difficult to avoid.
Where to put the CO2?
So the question is: what to do with this CO2? In the project, a consortium from research and industry investigated two options for such CO2 management.
For the two pilot projects, the researchers captured CO2 in the wastewater treatment plant ARA Bern. CO2 is produced there in a biogas plant. The biogas from the Bern WWTP consists of a gas mixture of methane (60 percent) and CO2 (40 percent). The CO2 must be separated in order to obtain high-purity methane, known as biomethane. After separation, the CO2 is converted into a liquid state. The liquid CO2 can then be filled into special tank containers and transported at a temperature of minus 35 degrees Celsius.
Long transportation to Iceland
Some of this CO2 was stored deep in the ground in Iceland. For storage in Iceland, the CO2 in the containers is transported by truck from the ARA Bern to the train station in Weil am Rhein (approx. 100 km). From there, the containers are first transported by rail to Rotterdam (approx. 800 km) and then by ship to Reykjavik (approx. 2200 km). So far, 80 tons of CO2 have been transported to Iceland in this way, according to background information on the project.
After arriving in Reykjavik, the containers are transported by truck to the geological storage site. Dissolved in seawater, the CO2 is injected into underground basalt rock, where it binds to the rock.
CO2 pipeline
Despite these transports, the method had a positive carbon footprint, as the researchers were able to show. This means that less CO2 was consumed during capture, transportation and storage than was stored.
The efficiency rate was around 80 percent. This means that for every tonne of CO2 that was stored, around 200 kilograms of CO2 were released. A large proportion of this during transportation. "This balance will improve in the future," said project manager Marco Mazzotti. This is because transportation will be less CO2-intensive in future.
To further reduce emissions, the researchers are also proposing a CO2 pipeline. There are already initial ideas for such a pipeline in Switzerland, said Burkard. However, he was unable to give a concrete timetable for such a pipeline.
"Already a business today"
For storage in concrete, the liquid CO2 is mixed with concrete granulate produced during the demolition of buildings. A chemical reaction causes the CO2 to fossilize, forming what is known as calcium carbonate. The CO2 remains stored as this in recycled concrete. To release the CO2 again, temperatures of over 600 degrees Celsius would be required - or a strong acid.
According to the project, this storage method also has a positive climate footprint. According to the project, storage in concrete has an efficiency of around 90 percent.
"CO2 storage in concrete is already a business today," emphasized Johannes Tiefenthaler. He is the founder of the ETH spin-off Neustark, which has further developed the process for storing CO2 in recycled concrete as part of the project. Twelve storage facilities based on this technology are already in operation and 20 more are under construction. The majority of these are in Switzerland, with others in Germany and Austria.
Regulatory difficulties
However, the researchers were surprised by the regulatory difficulties they encountered when transporting CO2 through several countries to Iceland, as they were told at the presentation. The project team therefore came to the conclusion: If Switzerland wants to store CO2 on a larger scale and create incentives for companies, clear regulations must be created together with its European neighbors.
The researchers also see a need for further research. For example, the extent to which it would be possible to store CO2 in Swiss soil should also be investigated.
©Keystone/SDA
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