Numerical Prediction of the Behavior of CO₂ Bubbles Leaked from Seafloor and Their Convection and Diffusion near Southeastern Coast of Korea

Abstract

Among various carbon capture and storage technologies to mitigate global warming and ocean acidification due to greenhouse gases, ocean geological storage is considered the most feasible for Korea due to insufficient inland space to store CO2. However, the risk of CO2 leakage and the behavior and environmental effects of the leaked CO2 need to be assessed for its successful implementation. Therefore, the behavior of CO2 bubbles/droplets dissolving into the surrounding seawater and the diffusion of dissolved CO2 by ocean flows should be accurately predicted. However, finding corresponding research has been difficult in Korea. Herein, the behavior and convection-diffusion of CO2 that was assumed to have leaked from the seafloor near the southeastern coast of Korea were numerically predicted using a multi-scale ocean model for the first time. In the simulation region, one of the pilot projects of CO2 ocean geological storage had started but has been temporarily halted. In the ocean model, hydrostatic approximation and the Eulerian–Lagrangian two-phase model were applied for meso- and small-scale regions, respectively. Parameters for the simulations were the leakage rate and the initial diameter of CO2. Results revealed that all leaked and rising CO2 bubbles were dissolved into the seawater before reaching the free surface; further, the change in the partial pressure of CO2 did not exceed 500 ppm during 30 days of leakage for all cases.

Keywords

• carbon capture and storage
• CO₂ ocean geological storage
• multi-scale ocean model
• hydrostatic approximation
• Eulerian–Lagrangian two-phase model
• environmental impact