Basalt core sample containing fixed carbon dioxide, or ‘carbon core’, created by injecting carbon dioxide dissolved in water into rock strata, collected from Hengill, southwest Iceland, 13th November 2014. The carbon dioxide was captured from the emissions of Hellisheiði geothermal power station near Reykjavík using direct air capture technology developed by Swiss company Climeworks, and injected underground as part of an interdisciplinary initiative known as CarbFix.

This sample is a product of the CarbFix project, which was initiated in Iceland in 2006 in order to demonstrate that it was possible to sequester, or ‘fix’, carbon captured from the air as mineral deposits in underground rock; in 2014, CarbFix became a subsidiary of Orkuveita Reykjavíkur. The carbon is visible as the white deposits in the sample.

This proof of principle is a major step forward in demonstrating the technical and economic viability of carbon capture – now believed by many governments and scientists to be essential as we attempt to reduce carbon emissions and limit dangerous climate change.