CO2 sequestration at sea by gas-lift system of shallow injection and deep releasing

To mitigate global warming, a system dissolving huge amounts of CO2 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 CO2 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 CO2 bubbles is used to transport CO2-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 CO2 gas into tap water. The liquid-phase flow caused by gas-rift effect was strong enough to transport the CO2-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 CO2 disposal into the deep ocean.