Rock-solid climate solution

A technique for turning CO2 into stone has been pioneered in Iceland, but another kind of immoveable object could prevent large-scale success.

The take-away

  • It took just a year and a half to turn 220 tonnes of CO2 into stone. Even the researchers were surprised by the speed.
  • Carbon capture and storage has long been a source of hope, but costs and public fears of leakage have stymied most efforts.

Meeting key international climate targets requires a multipronged approach. “You can do a lot with conservation and renewable energy, but every climate model shows that carbon capture is also needed,” explains Juerg Matter from the University of Southampton.

Carbon capture and storage (CCS) normally involves trapping CO2 from energy and industrial plants underground, injecting it into sedimentary rock, aquifers or old oil fields. CCS has long been a source of hope for climate change activists and researchers, but to date few efforts have stuck, owing to costs and public fears of leakage.

Now CarbFix, an Icelandic project led by Matter, has discovered a way to transform CO2 into rock, fixing it there permanently. “CO2, waste water and hydrogen sulphide – which is another emission from the thermal energy plant – are co-injected into basalt rock,” he explains.

Unlike sedimentary rock, basalt reacts with CO2, forming minerals such as calcite. The speed of the process even surprised the researchers; the carbonation of 220 tonnes of CO2 occurred in just a year and a half. Reykjavik Energy, the project’s industrial partner, is scaling the test by injecting 10,000 tonnes of CO2 this year. “If we can prove to the public that injected CO2 is converted to rock, that’s a strong selling point,” says Matter.

Unfortunately, without enforcing a price on carbon emissions, a suitable economic model is unlikely to emerge, leaving power companies little incentive to invest. How quickly could this technology be rolled out without such obstacles? “Within a decade,” responds Matter.

Juerg Matter (University of Southampton), CarbFix, Reykjavik Energy