CO 2 ocean sequestration by moving ships

Abstract

Ocean sequestration of the CO 2 captured from fossil-fuel burning is a possible option to mitigate the increase in CO 2 concentration in the atmosphere. It can isolate huge amounts of CO 2 from the atmosphere for a long time at relatively low cost, if it is acceptable from the viewpoint of the environmental impact on the ocean. The concept of CO 2 dispersion in the ocean depths by ships is a promising method for efficient dilution. That is, liquefied CO 2 is delivered to the site and injected into the ocean at depths of 1000-2500 m with a suspended pipe towed by a slowly moving ship. In addition to the horizontal movement of the release point, the vertical journey of CO 2 droplets until they disappear by dissolution is effective for the dilution of CO 2 in seawater. In this paper, the possibility of the generation of relatively large-sized droplets from a moving nozzle is investigated experimentally. In addition, the terminal velocity of CO 2 droplets in deepsea circumstances is measured in a large high-pressure tank to investigate the influence of the hydrate film formed on the surface of the droplet. Finally, it is shown by simulation that an initial dilution ratio of one to some ten thousandths is possible on a realistic engineering scale in the moving ship type of CO 2 ocean sequestration.

Biological impact assessment of direct CO2 injection into the ocean

“…Since 1) the biomass of the mid-ocean is significantly lower than that of the ocean-floor, and 2) the released CO 2 can rapidly dilute to about 1/50,000 its initial concentration [21], the ecosystem impact would not be at a detectable level within a small-scale experiment. The scale of a field experiment required for detecting ecosystem alteration induced by mid-depth CO 2 dispersion would be on nearly the same scale as the actual implementation scale of the technology.…”

2 Carbon Dioxide Capture and Storage

“…CO 2 could be transported by tanker for release from a stationary platform (Ozaki et al, 1995) or through a towed pipe (Ozaki et al, 2001). In either case, the design of CO 2 tankers would be nearly identical to those that are now used to transport liquid petroleum gas (LPG).…”

International Collaboration on Co2 Sequestration

“…Image analysis was employed to construct histograms of droplet size for different injection conditions. More details on research conducted at these facilities can be found in Nishio et al (2002) and Ozaki et al (2001).…”