ADVANCED CO_2 DILUTION TECHNOLOGY IN INTERMEDIATE DEPTH OF OCEAN

摘要

CO_2 sequestration in the ocean would be a highly advanced countermeasure to global warming if biological impact induced by CO_2 dissolution into ocean water is sufficiently small. Releasing liquid CO_2 droplets from a pipe towed by a ship is effective because of dilution due to the moving release point. If liquid CO_2 droplet sizes are controlled, dissolution into ocean water while rising up due to buoyancy, would take a long distance, which leads to vertical dilution. Dilution could be enhanced by a multi-nozzle array placed in the direction of ship width. Here we show that CO_2 dilution could be effectively further promoted by dispersing liquid CO_2 droplets horizontally by a turbulent wake formed by bodies placed at upper part of the multi-nozzle array. Turbulence formed at the downstream of the bodies could enlarge the width of rising liquid CO_2 droplets by turbulent mixing between sea water and droplets. We made a measurement of flow and statistical turbulent properties needed for numerical simulation behind a body. Based on the measured data, CO_2 enhanced dilution was simulated. Increase of partial CO_2 pressure(ΔpCO_2) and acidification (ΔpH) are drastically decreased as compared with the case without dilution. ΔpCO_2 larger than 1000μatm decrease to 56.1 % to 10.2% using the present dilution technology.