A new method for ocean sequestration of low-purity CO2 gas emitted from fired power plant is developed. This is a gas-lift pump system, named progressive gas lift advanced dissolution (P-GLAD) system, to dissolve only CO2 gas of combustion gas in seawater at shallow waters and to transport CO2-rich seawater to great depths. The system is an inverse-J pipeline set at the ocean at a depth between 200 and 3000 m and a releasing system of indissoluble gas. To improve the efficiency of the P-GLAD, one should elucidate bubbly flows accompanying gas phase dissolution formed in the gas-lift column of the system. In the present paper, first, the authors discuss mass transfer in bubbly flows of pure CO2 gas and filtrated tap water along the pipe axis in laboratory-scale P-GLAD of 25 mm in diameter and 7.69 m in height. Second, mass transfer in bubbly flows of mixed gas (95% volume of CO2 and 5% volume of pure air) and filtrated tap water in the same setup is discussed. The mass transfer coefficient of CO2 in the later system has the values of 3.1 x 10(-4)-8.5 x 10(-5). It is shown that the mass transfer coefficient is a function of the distance from the gas injection. Finally, the performance of the system is elucidated on the basis of the experimental and numerical investigations. The laboratory-scale P-GLAD dissolved over 98.5% of CO2 injected in the liquid phase.