著者

尾崎 雅彦 南浦 純一 北島 良則 溝上 宗二 竹内 和久 畠中 勝則

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本造船学会論文集 (ISSN:05148499)

巻号頁・発行日

no.187, pp.185-192, 2000-06

被引用文献数

3

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Ocean sequestration of the captured CO_2 from fossil fuel burning is a possible option to mitigate the increase of CO_2 concentration in the atmosphere. It can isolate huge amount of CO_2 from the atmosphere for long time in relatively low cost, if it is acceptable from the viewpoint of the oceanic environmental impact. The dissolution type treated in this paper is based on the idea that CO_2 dissolved and sufficiently diluted in seawater does no more harms than slightly increasing the concentration of CO_2 already contained in the seawater. The concept of CO_2 dispersion in the ocean depths by ship is a promising implementation for the efficient dilution. That is, liquefied CO_2 is delivered by ship to the site and injected into ocean depths of 1,000 to 2,500m with a suspended and towed pipe by a slowly moving ship. The constant movement of releasing point of CO_2 causes no stagnation and accumulation of CO_2 in seawater. The released CO_2 will form plenty of droplets, and then they rise gently due to the buoyancy, while reducing in the size to disappear by dissolution in the ambient seawater. Since the turbulent diffusion in the intermediate ocean is dominant horizontally, use of the vertical journey of CO_2 droplets will be very effective for the initial dilution. Thus, authors have good prospects for the dilution ratio of one to a hundred thousands in a couple of hours after injection on an engineering realistic scale, by means that the initial size of droplets is controlled. Drop formations from a fixed nozzle are investigated referring the common knowledge on textbooks. And the possibility of generating relatively large size of droplets from a moving nozzle is experimentally studied. As a result, it is found that the horizontal nozzle towed by the slowly moving ship is promising for the control of the drop formations in a realistic scale .

著者

尾崎 雅彦 南浦 純一 太田 真 佐々木 裕一 松浦 正己

出版者

公益社団法人日本船舶海洋工学会

雑誌

日本船舶海洋工学会論文集 (ISSN:18803717)

巻号頁・発行日

no.3, pp.87-95, 2006-06

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Ocean storage of the captured CO_2 from fossil-fuel burning is a possible option for mitigating the increase of CO_2 concentration in the atmosphere. Moving-ship type of CO_2 ocean storage is a concept whereby captured and liquefied CO_2 is delivered by ship to a site and injected into the deep ocean by means of a pipe suspended beneath a ship as it slowly moves through the water. In case of bad weather conditions, CO_2 marine transport and operation on the sea should be adjourned although CO_2 would be captured at the plant every day. It is, therefore, required that the system would have the buffer storage at the port and the extra shipping ability to recover the delay of schedule. Since the large scale of such spare capability might lead to the increase in cost, it is needed to investigate how to plan the system allowed for weather conditions reasonably. In this study, a time series model of sea state through one year is generated for a hypothetical ocean storage site, based on the wind data observed with satellite remote sensing, and simulations of CO_2 marine transport and operation on the sea are carried out considering the operational limit of sea state. In this approach, the continuing bad weather days or the frequent occurrences of rough sea condition during the specific season are counted automatically. In order to pursue higher efficiency of the operation, side-by-side type and tandem type of moorings are applied for the simulations and compared. Finally, cost assessments under the several assumptions are carried out to see the relative merits among that the number of ships would be increased, that the loading capacity of a ship would be increased, and that the storage capacity at the port would grow, which are generally in trade-off relationships.