A new study suggests CO₂ can be turned into stone in underground large-scale carbon capture sites.
Researchers at the University of Edinburgh tracked injected CO₂ at Iceland’s Carbfix site and found it had been permanently mineralised in volcanic basalt rock, using the gas’s own natural chemical “fingerprints” rather than artificial tracers.
The approach relies on analysing subtle variations in carbon, water and noble gas isotopes to follow what happens after CO₂ is dissolved in water and injected deep underground.
Samples taken from monitoring wells showed the gas reacting with the rock to form solid carbonate minerals, effectively turning CO₂ into stone.
The key point is verification. Large-scale CCS projects must demonstrate that stored carbon will not leak and is permanently secured.
Traditional monitoring methods can require added tracers and complex interventions. The Edinburgh team says using inherent isotopes and gases could provide a robust but lower-intervention monitoring and verification tool.
The findings align with previously reported mineralisation rates at Carbfix, reinforcing evidence that the process can be both rapid and durable.
Permanent mineral storage is also expected to attract higher-value carbon removal credits than many nature-based solutions, that may only store carbon for decades rather than centuries.
The research adds to earlier work suggesting UK volcanic formations could hold more than 3,000 million tonnes of industrial CO₂, roughly equivalent to 45 years of current industrial emissions.
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