Experiments and geochemical modelling of CO 2 sequestration by olivine: Potential, quantification B. Garcia a, * , V. Beaumont a , E. Perfetti a , V. Rouchon a , D. Blanchet a , P. Oger b , G. Dromart b , A.-Y. Huc a , F. Haeseler a a Institut Français du Pétrole, 1 et 4 Avenue du Bois Préau, 92852 Rueil Malmaison, France b Université de Lyon, CNRS, UMR 5570, ENS de Lyon, Site Monod, 15 Parvis René Descartes BP 7000, Lyon F-69342, France article info Article history: Received 18 March 2009 Accepted 18 June 2010 Available online 25 June 2010 Editorial handling by Dr. R. Fuge abstract Aqueous solutions equilibrated with supercritical CO 2 (150 °C and total pressure of 150 bar) were inves- tigated in order to characterize their respective conditions of carbonation. Dissolution of olivine and sub- sequent precipitation of magnesite with a net consumption of CO 2 were expected. A quantified pure mineral phase (powders with different olivine grain diameter [20–80 lm], [80–125 lm], [125– 200 lm] and [>200 lm]), and CO 2 (as dried ice) were placed in closed-batch reactors (soft Au tubes) in the presence of solutions. Different salinities (from 0 to 3400 mM) and different ratios of solution/solid (mineral phase) (from 0.1 to 10) were investigated. Experiments were performed over periods from 2 to 8 weeks. Final solid products were quantified by the Rock-Eval 6 technique, and identified using X-ray diffraction, Raman spectroscopy, electron microprobe and scanning electron microscopy. Gaseous compounds were quantified by a vacuum line equipped with a Toepler pump and identified and measured by gas chromatography (GC). Carbon mass balances were calculated. Olivine reacted completely with CO 2 , trapping up to 57 ± 2% (eqC of initial CO 2 ) as magnesite; some amorphous silica also formed. Olivine grain diameter and solution/mineral ratios appeared to be the pri- mary controls on the reaction, salinity acting as a second order parameter. During the experiments, fluid analyses may not be performed with approach adopted but, geochemical modelling was attempted to give information about the solution composition. This showed an interesting mineral matrix evolution. Under the experimental conditions, olivine appeared to be a good candidate for CO 2 trapping into a geo- logically stable carbonate, magnesite. The possible use of mafic and ultramafic rocks for CO 2 sequestra- tion is discussed. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Anthropogenic emissions of CO 2 , resulting from the combustion of fossil fuels, such as petroleum, gas and coal, represent 19 Gt of CO 2 /a. These quantities are one order of magnitude higher than the annual CO 2 production by volcanism or metamorphic pro- cesses and one order of magnitude higher than the natural seques- tration of CO 2 by geological processes (e.g. Kerrick et al., 1995). Carbon dioxide linked to anthropogenic activity is responsible for ca. 64% of the enhanced ‘‘greenhouse effect” (Bachu and Adams, 2003). Although some discrepancies exist on the extent of the con- sequences, all climate modelling experiments predict a significant global warming in the decades to come (Albritton and Meira Filho, 2001). The large scale efficient technologies for energy supply that prevail up to date are fossil fuel based. Consequently, CO 2 capture and sequestration is envisioned as a strategy to reduce the CO 2 emissions. Potential storage sites are:  ocean (direct release into the ocean water column or onto the deep sea-floor) (Holloway, 1997a; Bachu, 2000),  geological formations such as oil and gas fields, no longer ‘‘min- able” coal beds, deep saline formations and flood basalts (Bachu et al., 1994; Harrison et al., 1995; Bergman et al., 1997; Freund and Ormerod, 1997; Holloway, 1997a,b; Holloway et al., 1999; Koide et al., 1997; Bachu, 2000; McGrail et al., 2006). Oceans have a great potential for the storage of anthropogenic CO 2 (Herzog et al., 1997). Nevertheless the injected CO 2 in deep water would only be sequestered for an average residence time of approximately 1 ka. Furthermore, the injection of CO 2 in the 0883-2927/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeochem.2010.06.009 * Corresponding author.. Tel.: +33 (0) 1 47 52 53 17; fax: +33 (0) 1 47 52 70 19. E-mail address: Bruno.Garcia@ifp.fr (B. Garcia). Applied Geochemistry 25 (2010) 1383–1396 Contents lists available at ScienceDirect Applied Geochemistry journal homepage: www.elsevier.com/locate/apgeochem