To mitigate global warming, a system dissolving huge amounts of CO{sub}2 gas captured from fossil fuel fired power plants into the ocean with high acceptance by the ocean environment is indispensable. To this aim, we propose a sequestration system of CO{sub}2 in the deep ocean. The system is an inverse-J pipeline set in the ocean at a depth of 200-3000 m. In the system, a pumping effect by buoyancy of the dissolving CO{sub}2 bubbles is used to transport CO{sub}2-rich seawater to great depths. In the present paper, we discuss characteristics and performance of our proposal on the basis of experimental and numerical investigation. In a laboratory-scale experiment (pipe diameter of 25 mm and pipe height of 7.69 m), we observed over 98 dissolution of injected CO{sub}2 gas into tap water. The liquid-phase flow caused by gas-lift effect was strong enough to transport the CO{sub}2-rich water including nondissolved tiny bubbles into the deep ocean. Then a numerical simulation based on the experimentally derived models was applied to a system considering 10 MW class power plants. The results showed that our proposal is hopeful for an efficient method of CO{sub}2 disposal into the deep ocean.
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