Two years after Iceland's Hellisheidi power plant started its CarbFix Project, the facility can now successfully turn carbon dioxide into solid basalt rock for eternity.

Previous studies and the CarbFix project in Iceland reinforced that CO2 can be converted into solid form and stop it from merging with the atmosphere. Almost all the CO2 injected since the pilot was mineralized and turned into rock and, as a result, cleans the air of harmful emissions that exacerbates global warming.

Researchers and engineers involved in the CarbFix Project — from the University of Iceland, France's National Centre for Scientific Research, Columbia University in the United States, and Reykjavik Energy — have transformed the Hellisheidi power plant, the world's largest geothermal facility, into their own laboratory as they convert carbon dioxide into rock.

Turning CO2 Into Rocks

Iceland's volcanoes, transport sector, and industries produce large quantities of carbon dioxide. Turning carbon emissions into rock requires injecting the CO2 into porous basalt rocks and allowing it to mineralize or, in simpler terms, fixing carbon into the rock, hence CarbFix. This method, if done naturally, could take thousands of years.

In the laboratory, however, the process starts by capturing the geothermal steam after it's spun the turbines in the Hellisheidi power plant. The team turns the steam into liquid condensate and then dissolves it into water. This process is similar to making soda water out of CO2.

"The gas is fed in at the bottom of this tower, and then they put the cold water in at the top," said Pétur Már Gíslason of Reykjavik Energy. After which, the fizzy water is transported through pipelines and injected to a rock, 1,000 meters below the ground.

The pressurized liquid solution fills the cavities of the rock and initiates solidification process, in which atoms from the liquid begin to bond together and start to form crystals. In short, the soda water reacts with the rock underneath to produce new types of stones.

"With this method, we have actually changed the time scale dramatically," said Sandra Osk Snaebjornsdottir, a geologist working for the project.

Safest Way Of Carbon Storage

Studies showed that basalt rocks — formed from lava millions of years ago — can easily convert CO2 into carbonate minerals.

The CarbFix project reduces the plant's carbon dioxide emissions by a third, which amounts to 12,000 tonnes of CO2 captured and stored at a cost of about $25 per tonne.

Under the Paris climate agreement, Iceland has agreed to cut back its greenhouse gas emissions by 40 percent by 2030. However, its emissions increased by 2.2 percent from 2016 to 2017 and went up by 85 percent since 1990, according to Iceland's Environment Agency.

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