Turning CO2 into Solid Rock

Jacqueline Mullin

What do you get when you mix carbon dioxide and hydrogen sulphide with water and then inject it into the dark, fine-grained volcanic rock known as basalt? According to scientists from Columbia University, University of Iceland, University of Toulouse and Reykjavik Energy, you get solid rock.

Referring to the study recently published in the journal, Science, lead author Juerg Matter, Associate Professor of Geoengineering at the University of Southampton recently shared that “our results show that between 95 and 98 percent of the injected CO2 was mineralized over the period of less than two years”.

While the process of capturing and storing CO2 underground is not new, the discovery that it does not take long for the carbonate minerals to begin forming after the solution is injected into the volcanic basalt under the earth’s surface is new information.

Capturing and then storing CO2 underground has been an important strategy for meeting emissions reductions targets, yet the practice creates huge risk in terms of carbon leakage. In recent years, geologists and engineers have been looking at the mineralization of carbon to dispose of CO2, but scientists have warned that it could potentially take hundreds or even thousands of years to complete the process.

Looking for a new tool in the fight against climate change, the prevalence of basalt underneath the earth’s surface and the suggestion that sea water can be used in place of fresh water, makes the process of carbon capture a viable option, (the process requires a lot of water). Additionally, researchers with the CarbFix project, a group focusing on locking away carbon dioxide, were emphasized the stability and longevity of the process by suggesting that carbonate minerals will not leak.

While the CarbFix team admits they weren’t sure going into their experiment how the process would evolve, it turned out much better than they could have hoped. They initially estimated the process would take eight to 12 months, but the conversion from basalt to a white chalky solid took place in a matter of months.

A number of questions, from uses for the newly formed rocks, to a need to determine how the process will unfold in large-scale attempts, are the new focus of dialogue surrounding the idea of turning CO2 into rock. But the recent success of the CarbFix project suggests that capturing and storing carbon dioxide may allow for a noticeable reduction in greenhouse gas emissions.