Rapid & permanent greenhouse gas removal via carbon dioxide mineralisation - the CarbFix project
Prof. Juerg M. Matter, University of Southampton
Mineralisation of CO2 via CO2-fluid rock reactions has been proposed as the most permanent solution for geologic CO2 storage. However, as of today, it was unclear how fast CO2 is converted to carbonate minerals in-situ in geologic reservoirs. The CarbFix I project in Iceland was designed to verify in-situ CO2 mineralisation in basaltic rocks. Two injection tests were conducted at a pilot injection site near the Hellisheidi geothermal powerplant, SE of Reykjavik. 175 tons of pure CO2 and 73 tons of a CO2+H2S mixture were injection from January to March 2012 and in June 2012, respectively. The gases were injected fully dissolved in groundwater into a permeable basalt formation between 400 and 800 m depth using a novel CO2 injection system. Using conservative (SF6, SF5CF3) and reactive (14C) tracers, we quantitatively monitored and detected dissolved and chemically transformed CO2. Mass balance calculations using the tracer data reveal that up to 95% of the injected CO2 has been mineralized over a period of less than two years. Based on these promising results, CarbFix scaled up the injection and integrated it with the operation of the Hellisheidi geothermal power plant in 2014. Currently, approximately 10,000 tonnes of CO2 and 6,000 tonnes of H2S are injected annually.

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