Scientists are turning CO2 into rock, reducing emissions

Iceland is reducing CO2 in the atmosphere by pumping it underground. It will be turned into rock in just a few months.

There are many examples of carbon capture and sequestration (CCS), a system mainly used in thermoelectric power plants to reduce the emissions of the combustion process.

CO2 can be turned into rock within months. Photo by Kevin Krajick/Lamont-Doherty Earth Observatory

However, the drawback of costs and how to find proper spaces in which storing carbon dioxide while avoiding uncontrollable leakage makes this system difficult to use. For this reason, a new experiment called Carbfix, conducted by a team of international scientists, could change the future of the carbon capture and sequestration.

In Iceland, a land rich in basaltic rocks, researchers have demonstrated that pumping CO2 underground is possible and that, in certain physical and chemical conditions, it becomes carbonate rock.

Hellisheidi geothermal power plant in Reykjavik, Iceland. Photo via Brennan Linsley /AP

Capturing CO2 at the Hellisheidi geothermal plant

The study, published in Science, shows for the first time ever that storing CO2 in a permanent and stable way is feasible. And what surprises the most is processing time. While rocks take geological eras to become such, Carbfix allows carbon dioxide to become carbonate rock in less than 2 years, a blink of an eye for geology.

Moreover, the researchers have showed that 95 per cent of the CO2 pumped underground to a depth of 400 to 800 metres has been tuned into stone. “Our results demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated,” reads the paper.

“Carbonate minerals do not leak out of the ground, thus our newly developed method results in permanent and environmentally friendly storage of CO2 emissions,” said Juerge M. Matter, the study’s lead author. “On the other hand, basalt is one of the most common rock types on Earth, potentially providing one of the largest means of CO2 storage capacity.” The experiment has been conducted at the Hellisheidi geothermal power plant outside Reykjavik, where 5,000 tonnes of CO2 are pumped underground every year to be turned into stone.

The project has some limits

In order to turn CO2 into rock, huge quantities of water are needed. In fact, carbon dioxide is mixed with water to lower pH and to make it react with basalt. The ratio of water to CO2 is 95 per cent to 5 per cent. And scientists claim that using sea water isn’t feasible and costs to build these kind of plants would be high. In any case, the project represents a step forward for finding a solution to reduce greengouse gas emissions.

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