CO2 sequestration trial on Iceland

Iceland plans to remove CO₂ from the air and then pump it into the ground and store it in the rock. The CarbFix2 project of Swiss start-up Climeworks and Iceland's Reykjavik Energy was launched last week.

The special feature of this project is that the CO₂ is being removed from the air. That is a major difference versus the CO₂ sequestration proposed in the latest coalition agreement. The latter aims to store some of the CO₂ emissions from energy-intensive companies in the ground. At best, that concept simply prevents some extra CO₂ from entering the atmosphere, but does nothing to reduce the volume of greenhouse gases already in the air. A second difference is that the sequestration intended by the coalition agreement stores CO₂ in gas bottles, while the CO₂ in Iceland's project is sequestrated to the ground.

Plenty of heat available

Climeworks provides the technology to scrub CO₂ from the air. Fans are used to blow air through a filter containing an amine, a substance commonly used to capture CO₂. One issue with this is that removing CO₂ from the amines requires lot of heat, and that's no different with the Climeworks technology. However, if that heat is close to hand in large quantities, then it doesn't matter that the removal of the CO₂ from the filter requires a lot of energy. And that's exactly what we find on Iceland: the volcanic island has vast amounts of geothermal heat.

Basalt

Iceland has yet another advantage. The substrate into which the CO₂ is pumped is basalt rock, with which the CO₂ forms a chemical compound. This means that the CO₂ does not remain in the gas phase in the ground, but inextricably mineralises with the rock. Last year, it was also demonstrated that this mineralisation process occurs much faster than had been expected. According to Energy Reykjavik, Iceland has now permanently sequestrated some 18,000 tons of CO₂ at $30 per ton.
 

The CarbFix2 project is located in Hellisheidi, close to Iceland's capital city. That's where the island's largest geothermal power plant is sited. This plant has a capacity of 300 MW of electricity and 130 MW of heat. The project is intended to test the technology, according to the Climeworks website. The trial involves sequestrating 50 tons of CO₂ per year. Climeworks already has a plant in Switzerland that removes some 1,000 tons of CO₂ from the air annually and supplies it to nearby greenhouses. Climeworks claims a price per ton of CO₂ of $100.

Barely a drop in the ocean

The benefit of combining removal of CO₂ from the air with binding it in basalt is that this can be done anywhere on earth where basalt formations are found beneath our feet. So CO₂ sequestration does not necessarily need to occur at fossil fuel-powered power plants or industrial plants with high CO₂ emissions. At the same time, however, the stats indicate that the volume of CO₂ removed from the air is still barely a drop in the ocean. Given the total human emissions of some 37 billion tons of CO₂ per year, 1,000 tons is really not very much at all. What's more, not every location is going to have access to a sufficient (sustainable) heat source.

Climeworks is not the only company wanting to remove CO₂ directly from the air. Global Thermostats uses a similar technology as Climeworks, and Carbon Engineering uses a system with calcium oxide. Carbon Engineering is currently building a plant that does not store the sequestrated CO₂ in the ground, but uses hydrogen to convert it directly to petrol or diesel.

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Opening photo: the CO₂ collector on Iceland. Photo: Climeworks / Zev Starr-Tambor.
 

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