Iceland turns CO2 to rock

In the heart of Iceland’s volcano country, 21st-century alchemists are transforming carbon dioxide into rock for eternity, cleaning the air of harmful emissions that cause global warming.

The technology mimics, in accelerated format, a natural process that can take thousands of years, injecting CO2 into porous basalt rock where it mineralises, capturing it forever.

The UN Intergovernmental Panel on Climate Change is promoting various carbon capture and storage (CCS) methods in a bid to limit the rise in average temperatures to 1.5 degrees Celsius.

In Iceland’s CarbFix project researchers and engineers from utility company Reykjavik Energy, the University of Iceland, France’s National Centre for Scientific Research (CNRS) and Columbia University in the United States work.

In Iceland, a country of geysers, glaciers and volcanoes, at least half of the energy produced comes from geothermal sources. That’s a bonanza for CarbFix researchers, who’ve turned the Hellisheidi geothermal power plant -- one of the world’s biggest -- into their own laboratory.

The plant, located on the Hengill volcano in southwestern Iceland, sits on a layer of basalt rock formed from cooled lava, and has access to virtually unlimited amounts of water.

The plant pumps up the water underneath the volcano to run six turbines providing electricity and heat to the capital, Reykjavik, about 30 kilometres (18 miles) away.

The CO2 from the plant is meanwhile captured from the steam, liquified into condensate, then dissolved in large amounts of water.

“So basically we are just making soda water out of the CO2,” says project director Edda Sif Aradottir. The fizzy water is piped several kilometres to an area where grey, igloo-shaped domes dot a lunar-like landscape.

Here the fizzy water is injected under high pressure into the rock 1,000 metres (3,300 feet) under the ground.

The solution fills the rock’s cavities and begins the solidification process -- a chemical reaction that occurs when the gas comes in contact with the calcium, magnesium and iron in the basalt.

Once the CO2 is turned to rock, it’s pretty much captured there for good.

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 a tonne.