Mineral sequestration of carbon dioxide in basalt: A pre-injection overview of the CarbFix project |
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Authors: | Sigurdur Reynir Gislason Domenik Wolff-Boenisch Andri Stefansson Eric H Oelkers Einar Gunnlaugsson Hólmfridur Sigurdardottir Bergur Sigfusson Wallace S Broecker Juerg M Matter Martin Stute Gudni Axelsson Thrainn Fridriksson |
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Institution: | 1. Reykjavík Energy, Bæjarháls 1, 110 Reykjavík, Iceland;1. Geosciences Environment Toulouse (GET), CNRS UMR 5563, 14 Avenue Edouard Belin, Toulouse 31400, France;2. Earth Science, University College London, Gower Street, London WC1E 6BT, UK |
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Abstract: | In this paper we describe the thermodynamic and kinetic basis for mineral storage of carbon dioxide in basaltic rock, and how this storage can be optimized. Mineral storage is facilitated by the dissolution of CO2 into the aqueous phase. The amount of water required for this dissolution decreases with decreased temperature, decreased salinity, and increased pressure. Experimental and field evidence suggest that the factor limiting the rate of mineral fixation of carbon in silicate rocks is the release rate of divalent cations from silicate minerals and glasses. Ultramafic rocks and basalts, in glassy state, are the most promising rock types for the mineral sequestration of CO2 because of their relatively fast dissolution rate, high concentration of divalent cations, and abundance at the Earth's surface. Admixture of flue gases, such as SO2 and HF, will enhance the dissolution rates of silicate minerals and glasses. Elevated temperature increases dissolution rates but porosity of reactive rock formations decreases rapidly with increasing temperature. Reduced conditions enhance mineral carbonation as reduced iron can precipitate in carbonate minerals. Elevated CO2 partial pressure increases the relative amount of carbonate minerals over other secondary minerals formed. The feasibility to fix CO2 by carbonation in basaltic rocks will be tested in the CarbFix project by: (1) injection of CO2 charged waters into basaltic rocks in SW Iceland, (2) laboratory experiments, (3) studies of natural analogues, and (4) geochemical modelling. |
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