The CarbFix Pilot Project–Storing carbon dioxide in basalt

In situ mineral carbonation is facilitated by aqueous-phase chemical reactions with dissolved CO2. Evidence from the laboratory and the field shows that the limiting factors for in situ mineral carbonation are the dissolution rate of CO2 into the aqueous phase and the release rate of divalent cations from basic silicate minerals. Up to now, pilot CO2 storage projects and commercial operations have focused on the injection and storage of anthropogenic CO2 as a supercritical phase in depleted oil and gas reservoirs or deep saline aquifers with limited potential for CO2 mineralization. The CarbFix Pilot Project will test the feasibility of in situ mineral carbonation in basaltic rocks as a way to permanently and safely store CO2. The test includes the capture of CO2 flue gas from the Hellisheidi geothermal power plant and the injection of 2200 tons of CO2 per year, fully dissolved in water, at the CarbFix pilot injection site in SW Iceland. This paper describes the design of the CO2 injection test and the novel approach for monitoring and verification of CO2 mineralization in the subsurface by tagging the injected CO2 with radiocarbon (14C), and using SF5CF3 and amidorhodamine G as conservative tracers to monitor the transport of the injected CO2 charged water.