Shafts of calcite mineral grow rapidly on basalt after exposure to supercritical CO2 for 30 days.
Federal scientists working at PNNL today unveiled results of research that appear to show that carbon dioxide can be permanently stored in deep underground basalt formations with little or no threats to safety. A PNNL news release states that facility staff
“have discovered key factors that show water-saturated liquid CO2, under conditions mimicking deep geologic settings, will plug cracks within the rock that otherwise might allow the hazardous greenhouse gas to escape. . . . [W]ater-saturated liquid CO2 – CO2 gas in a supercritical phase – showed similar or even greater reactivity than observed for CO2-saturated water. The swift chemical reaction detected on metal and oxide surfaces, as well as the silicate surfaces found in basalt rock.”
Pete McGrail, the chief researcher on this project, said more work needs to be done to extend the findings beyond basalt, especially in model development for reactions in the liquid or supercritical CO2 phase: “Although these initial experiments focused on basalt, the principles are not unique to basalts and would apply generally to other reservoir systems and caprocks,” McGrail said. Pilot injection projects are apparently being planned as a followup to this study.