Global Climate & Energy Project
CO2 StorageReactivity of CO2 in the Subsurface
Start Date: September 2010
Kate Maher, Dennis Bird and Gordon Brown1, Department of Geological and Environmental Sciences, Stanford University (1Co-Appointment in Department of Photon Science, SLAC National Accelerator Laboratory at Stanford)
The goal of this research program is to discover novel techniques for accelerating the conversion of carbon dioxide into carbonate minerals that can be sequestered underground. The research team will focus on understanding the chemical reactions that occur when CO2 is injected into silicate rocks rich in magnesium and calcium. Using field studies and laboratory analyses, researchers will determine the optimum geochemical conditions for converting captured CO2 into carbonates, and will test various organic acids and natural enzymes that could significantly increase reaction rates, thereby speeding up the formation of carbonates for permanent underground storage.
About 60% of global CO2 emissions come from power plants and industrial smokestacks. This study focuses on two promising techniques for storing these emissions underground: (1) the injection of CO2 into deep saline solutions; and (2) mineralogical sequestration – the permanent trapping of CO2 in stable carbonate minerals. Mineralization results from the chemical reaction of CO2 with magnesium- and/or calcium-rich silicates found in two types of rock: mafic (basalts) and ultramafic (peridotites and serpentinites). See Figure 1.
1. Dissolution of CO2 into aqueous solutions;
Laboratory studies will be guided by parallel field studies of CO2-brine mixtures in sedimentary aquifers (e.g., Bravo Dome in New Mexico) and in crystalline rocks that have undergone mineral carbonation (e.g., Red Mountain, California). See Figure 2. Researchers will apply a variety of analytic techniques, including thermodynamic and kinetic modeling, mineralogical studies, surface chemistry, isotopic tracers, reactive transport modeling, and geological experience and observations. A major goal is to find new ways to increase the relatively slow dissolution kinetics that occur when acidic solutions react with silicate minerals and CO2 to form carbonates. The results will improve our understanding of the timescales of mineral carbonation and could lead to new strategies for enhancing storage of CO2 in the aqueous and solid phases.
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