ccs Environment

At CarbFix, captured CO₂ is first dissolved in large volumes of water to form carbonated fluid, then injected several hundred meters down into basaltic rock. Dissolved CO₂ is far more reactive than the supercritical phase: it rapidly reacts with calcium-magnesium silicates in the rock, precipitating calcite and other carbonate minerals. Isotope tracers in monitoring wells showed that over 95% of the injected CO₂ was mineralized in less than two years, permanently locked into solid carbonates and largely free of leakage risk and post-closure monitoring burdens; the method requires ample water and suitable rock formations.

Supercritical CO₂ (above 31.1 °C and 7.38 MPa) is nearly as dense as a liquid but flows almost like a gas, so it fills deep saline-aquifer pore space with far greater volumetric efficiency than gaseous CO₂, raising storage capacity per reservoir and cutting pressure losses in the well. Underground, it is progressively immobilized by structural trapping beneath the caprock, then by residual, solubility, and mineral trapping, so containment generally improves with time.

At first, supercritical CO2 is held underground by structural trapping beneath low-permeability caprock. Capillary forces then snap it off into residual droplets stuck within pores. Dissolved CO2 makes brine denser so it sinks, weakening the buoyant drive to escape, and slow geochemical reactions fix a small share of carbon into solid carbonate minerals. These four mechanisms take over in succession, so overall leakage risk declines.