The study found that captured CO2 injected into volcanic rocks in Iceland was successfully locked away as solid minerals, as shown by its natural chemical “fingerprints”.
Lead author Dr Chris Holdsworth, who carried out the work during his PhD at the University of Edinburgh, is now an MRV technical specialist at Carbfix. “We can use the natural fingerprints already present in the CO2 and water to track when CO2 dissolves and turns to stone, without adding anything extra underground. This has real potential to simplify and reduce the cost of monitoring as storage projects scale up,” he said.
The approach reduces the need to add artificial tracers and could make it simpler and cheaper to prove that CO2 is stored safely and permanently underground – a key requirement for large-scale CCS projects serving hard-to-abate industries such as cement and steel production.
This mineralisation method locks away CO2 permanently, so its carbon removal credits are expected to command higher prices than many nature-based projects, which may only store carbon for 100 years or less.
Researchers tracked what happened to injected CO2 at mineralisation operator Carbfix’s storage site in Iceland by analysing tiny, naturally occurring differences in the types of carbon, water and noble gases in the system.
The CO2 was dissolved in water, injected deep into basalt rock, and then monitored over time using these natural chemical signatures. Samples from underground monitoring points showed the CO2 reacting with the rock to form solid carbonate minerals.
Professor Stuart Gilfillan, Personal Chair of Geochemistry at the University of Edinburgh, who led the study, said, “Simple, reliable checks are essential for public trust in carbon storage and for regulators and investors to sign off major projects. Using these natural fingerprints can streamline monitoring while providing the evidence that mineral storage is permanent.”
The study, published in the International Journal of Greenhouse Gas Control and funded by the Natural Environment Research Council (NERC), demonstrates that using inherent isotopes and gases could offer a robust, lower-intervention monitoring and verification (MRV) tool for commercial CO2 storage.
Overall, the monitoring data lined up with mineralisation levels previously reported at the Carbfix site, adding weight to earlier evidence that the process is fast and secure.
Dr Susan Bodie, Head of Innovation Development and Licensing at Edinburgh Innovations, the University of Edinburgh’s commercialisation service, said,“These results present an important validation for a novel, sustainable method of measuring carbon capture and storage, which can help deliver help deliver net-zero targets for emissions-intensive sectors, as well as support financing and regulation.”
Dr Chris Holdsworth and Prof Stuart Gilfillan collecting samples at one of the Carbfix sites at Nesjavellir geothermal power plant in Iceland
