해양지중 저장 중 누출된 이산화탄소의 다중규모 확산 시뮬레이션을 위한 기초적인 연구

Abstract

Carbon Capture and Storage(CCS) is a technology to capture and store carbon dioxide(CO2), which is a representative greenhouse gas. Since its potential to reduce large amount of CO2 and feasibility, many countries are working on various CCS methods and projects. CCS can be categorized by geological sequestration(=storage), ocean sequestration and geological sequestration under seafloor, among which the last one is the most proper option to Korea since there is not enough inland space to store CO2. However, public acceptance is an unknown factor in developing public policy involving CCS technology. Characteristics of CCS substantially differ from other options for CO2 mitigation, particularly when assessing the risks of leakage and development of appropriate regulatory penalties in implementing some form of CCS. Therefore, to carry out geological sequestration of CO2 under seafloor, it is inevitable to evaluate the risk of leakage, to monitor the behavior of leaked CO2 and to assess the environmental effect by the leaked CO2. The CO2 in seawater can exist as liquid or gas phase depending on its surrounding environments, mainly pressure and temperature. Therefore, the behavior of CO2 bubbles with dissolving into surrounding sea-water and diffusion of dissolved CO2 (DCO2) by ocean flows should be accurately predicted for the assessment of environmental impacts. In this study, the behavior and diffusion of CO2, which is purposely stored under seafloor and leaked from it, bubbles and DCO2 in the sea-water was numerically predicted by multi-scale ocean model, where hydrostatic approximation and Eulerian-Lagragian two phase model is applied for meso- and small-scale region, respectively. Two cases are selected by assumed leaking-amount of CO2, that is 3,800ton/year and 94,600ton/year, and numerical simulations are performed for the cases. The results including the change of partial pressure of CO2(pCO2), which is one of the most important criteria for environmental impacts on marine biota, are qualitatively compared with each other.