A new study demonstrating for the first time that CO2 can be permanently and rapidly locked away in volcanic rock could give fresh impetus to efforts to develop large-scale Carbon Capture and Storage (CCS) technology.
During the study – which was led by Columbia University, University of Iceland, University of Toulouse and Reykjavik Energy – CO2 was injected into a deep well at a study site in Iceland.
The CO2 was dissolved in water and carried down the well. On contact with the target storage rocks, at 400-800 metres under the ground, the solution quickly reacted with the surrounding basaltic rock, forming carbonate minerals.
To monitor what was happening underground, the team injected ‘tracers’, chemical compounds that literally trace the transport path and reactivity of the CO2.
There were eight monitoring wells at the study site, where they could test how the chemical composition of the water had changed. The researchers discovered that by the time the groundwater had migrated to the monitoring wells, the concentration of the tracers – and therefore the CO2 – had diminished, indicating that mineralisation had occurred.
Until now it was thought that this process would take several hundreds to thousands of years and was therefore not a practical option. But the current study has demonstrated that it can take as little as two years.
“Our results show that between 95 and 98 per cent of the injected CO2 was mineralised over the period of less than two years, which is amazingly fast,” said Dr Juerg Matter, Associate Professor in Geoengineering at Southampton University, and lead author of a paper on the project published in Science.
The investigation is part of the so-called CarbFix Project, a European Commission and US Department of Energy funded programme to develop ways to store anthropogenic CO2 in basaltic rocks through field, laboratory and modelling studies.
The team is now working on a scaled up version of the study at Reykjavik Energy’s Hellisheidi geothermal power plant, where up to 5,000 tonnes of CO2 per year are captured and stored in a basaltic reservoir.