Plant "petrified" CO2 from the air

Iceland's pilot project combines direct air capture with mineralization for the first time

At the Hellisheidi geothermal power plant in Iceland, CO2 is being converted from the air to stone for the first time. © Arni Saeberg / Carbfix
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Captured and fossilized: In Iceland, carbon dioxide will in future be converted from air into carbonate rock - and thus removed from the climate system. A pilot plant now installed filters CO2 from the ambient air and sends the gas underground. Chemical reactions in the porous basalt rock cause the CO2 to mineralize to carbonate. That this fossilization works, have already proven previous pilot tests - now this is combined for the first time with Direct-Air-Capture.

It sounds tempting: If we can not manage to reduce our CO2 emissions enough, we could remove the greenhouse gas from the air later on. However, this so-called "Direct Air Capture" (DAC) was long considered to be less effective and too expensive. But in the summer of 2017, the first commercial system for direct air capture in Switzerland went into operation - it should prove that this technology can be worthwhile.

Air capture and petrification combined

Now the makers of the Swiss plant have gone a step further: The company Climeworks has brought one of their "CO2-Schlucker" systems to Iceland and there combined with a completely new method of CO2 storage. Hellisheidi, the Icelandic geothermal power plant, has been piloting CO2 for some time, turning CO2 into rock.

The white carbonate crystals in this basaltic core show where CO2 has been mineralized. © Sandra O Snaebjornsdottir

The trick here: The dissolved in water greenhouse gas is pumped 400 to 800 meters deep in the traversed by hydrothermal springs underground. In the porous basalt rock, a chemical reaction takes place, which transforms the CO2 into carbonate within less than two years - and thus into solid rock. Thus mineralized, the CO2 is permanently withdrawn from circulation.

"Great potential"

By combining this "fossilization" with Climeworks' Direct Air Capture module, CO2 can now be directly mineralized from the ambient air. "We have proven that the greenhouse gas can be permanently mineralized, " explains CarbFix project leader Edda Sif Arad ttir of Reykjavik Energy. "With the integration of the Climeworks technology, we now have a solution that can be used wherever there is basalt rock, regardless of emission sources." Display

The principle of direct-air capture in combination with fossilization. Climeworks

Project participants hope that this combination of both technologies can in the future help to curb climate change. In fact, there is some evidence that climate protection without such geoengineering technologies will probably not work. "The potential for scaling our technology in combination with CO2 storage is huge, " says

Christoph Gebald, co-founder and CEO of Climeworks: "And not just here in Iceland, but in many other regions with similar rock formations."

(Climeworks / Carbfix, 13.10.2017 - NPO)