A new study has found that carbon dioxide can be converted into stone at large-scale underground carbon capture sites, a process that offers a new direction for carbon removal technology. Researchers from the University of Edinburgh tracked injected CO2 at Iceland's Carbfix site, confirming its permanent mineralization in volcanic basalt by analyzing the gas's own natural chemical "fingerprint."

The method utilizes subtle variations in carbon, water, and noble gas isotopes to monitor the dynamics of CO2 after it dissolves in water and is injected underground. Samples collected from monitoring wells show that the gas reacts with the rock to form solid carbonate minerals, effectively converting CO2 into stone and achieving long-term carbon storage.

Verifying the safety of carbon capture and storage projects is crucial. Traditional monitoring methods often require adding artificial tracers and complex interventions, whereas the Edinburgh team points out that using inherent isotopes and gases can provide a more robust, less invasive monitoring tool, ensuring that stored carbon does not leak.

These findings are consistent with previously reported mineralization rates at the Carbfix site, strengthening evidence that the process is both rapid and long-lasting. Permanent mineral storage is expected to offer advantages over many nature-based solutions, which may store carbon for only decades, as mineral storage can last for centuries, thereby attracting higher-value carbon removal credits.

This study complements earlier work suggesting that volcanic rock formations in the UK could accommodate over 3 billion tonnes of industrial CO2, roughly equivalent to 45 years of current industrial emissions. This provides an important reference for global carbon management strategies, particularly in regions such as Europe, Iceland, and the UK.