Surface Mixing as Method for Minimizing Leakage Risk in CO2 Sequestration Surface Mixing as Method for Minimizing Risk in CO2 Sequestration

Abstract The economic feasibilities of geologic CO 2 sequestration and stakeholder acceptance of the technology must account for the risk of leakage from the target formation. The standard approach to geologic sequestration assumes that CO 2 will be injected as a bulk phase. In this approach, the primary driver for leakage is the buoyancy of CO 2 under typical deep conditions (depths > 800 m). An alternative approach is to dissolve the CO 2 into brine at the surface, then inject the saturated brine into deep subsurface formations. The CO 2 -laden brine is slightly denser than brine containing no CO 2 , so ensuring the complete dissolution of all CO 2 into brine at the surface prior to injection will eliminate the risk of buoyancy-driven leakage. In this paper, we examine the feasibility of dissolution of CO 2 in surface facilities and injection of the saturated brine. We compute the incremental cost of the additional processes and facilities relative to injecting bulk phase CO 2 . We also estimate the power requirements to determine the operating costs. The incremental capital and operating costs can be regarded as the price of this form of risk reduction. A full cost-benefit assessment requires an estimate of the cost of long-term monitoring for leakage. Such an estimate is beyond the scope of this study.