Carbon Capture Storage method is expected to be counterpart for global warming but it holds also a risk of CO2 leaking in the sea. CO2 hydrate formation has the potential of solving the problem. The aim of this work is to build CO2 hydrate formation model based on previous studies. In order to determine hydrate growth rate, matching with temperature rise of experimental result, interface mobility parameter was decided.
After several numerical calculations, the order of interface mobility parameter was identified.
As one of the methods to suppress the global warming, Carbon Capture and Storage(CCS) attracts much attention over the world.
CCS method is gathering CO2 gases from big emission source such as factory or thermal power plant and accumulating them under the seafloor.
By the method, it can be expected to reduce the concentration of CO2 in the atmosphere. In the other hand, CCS method holds also the risk of CO2 defluxion in the sea. If stored CO2 leak into the sea, it may make impacts to ecological system in the sea and CO2 concentration in atmosphere.
To prevent the CO2 defluxion from the seabed CO2 hydrate technology is taken into account. CO2 hydrate has cage structures that trap CO2 molecules in water molecules. Hydrate is stable under high temperature and low temperature condition. Though the areas in which CO2 is stored are unstable for hydrate structure, if accumulated CO2 gases arrived seafloor in which temperature become lowest, it makes hydrate structure. Then generated CO2 hydrates reduce the width of CO2 gases flow to the sea (Fig. 1).
To estimate how much CO2 hydrate can block the CO2 gases flow, it is necessary to calculate change of permeability under the sea floor by the CO2 hydrate generation.
As previous work, (Fukumoto 2013) used the Phase-Field Model (PFM), which simulates the growth of CH4 hydrate and calculated permeability change in porous media.
The objective of this research is to develop a PFM for the growth of CO2 hydrate, based on the model of Fukumoto (2013) in order to evaluate how CO2 hydrate formation prevents the gas leakage.
Huge earthquakes on the Nankai Trough which is located in the offshore of Shikoku island and Ki-i peninsula, Japan may occur in the coming years. Ships under tsunami attack in that bay may be uncontrollable, collision, drifting, grounding, etc. It is decided, to avoid such a dangerous situation, that mooring, arriving or leaving ships should evacuate to a safety area as soon as possible and be anchored there, (and let tsunami go away). The purpose of this paper is calculation of anchoring ships’ motions under tsunami attack using mathematical models, and therefore, discussed and evaluated for the safety guidelines. INTRODUCTION The Nankai Trough is a submarine trough located with south of Japan’s island of Honshu, extending approximately 900 km offshore along the south coastline. The trough outlines a subduction zone that is caused by subduction of the Philippine Sea Plate beneath Japan, which’s part of the Eurasian plate. Huge earthquakes have occurred at intervals of 150 years to 100 years in the trough, as shown in Figs.1-2. Moreover, it is estimated that there is a 50% probability of a tsunami being generated by an earthquake in this area in the next 30 years. Tsunamis may occur after an earthquake, and the tsunami arriving time to Osaka Bay is around 1h. Consequently, ships may begin to move uncontrollably, subjecting piers to tremendous sideways forces, and crash relentlessly against breakwaters. Ultimately, vessels are set adrift and run aground. That is a large number of important industrial facilities exist around Osaka Bay, several research projects concerning measures against tsunamis have been undertaken. The shallow Seto Inland Sea is 450 km long from east to west. Its width from south to north varies from 15 to 55 km. The average depth is 37 m and the greatest depth is 105 m.
Kawano, Kenji (Department of Ocean Civil Engineering, Kagoshima University) | Kimura, Yukinobu (Department of Ocean Civil Engineering, Kagoshima University) | Ito, Keisuke (Department of Ocean Civil Engineering, Kagoshima University) | Tanaka, Nozomu (Department of Ocean Civil Engineering, Kagoshima University)
The offshore structure is expected to have important roles on development of wind energy production system. The steady wind force, which can be provided to generate the wind energy production, would be available in the coast area with water depth about 50m. The uncertainty effects on the dynamic response evaluation of the idealized offshore platform model with offshore wind energy production are examined with wave force and seismic force in the present study. The deterioration effects of the structure on the response evaluation are also discussed with the simplified model. Furthermore, it is examined about the reduction effects on the seismic response by base isolation system installed at the deck of the structure. For the reliability evaluation of the offshore platform with the wind energy production, it is essential to carry out the available estimation to the dynamic force with uncertainty.
The offshore structure has great possibilities of development of wind energy production system. It is so effective to the reduction of greenhouse gas emissions that it is essential to carry out development of the offshore wind energy production. The steady wind force, which can be provided to generate the wind energy production, would be available in the coast area with water depth about 50m (Hendersons (2002)). The environmental condition of the offshore structure is more severe than the land structure. If the offshore structure is located in the seismic activity area, it is essential for the reliable design of the structure to carry out the dynamic response estimation on the wave force and seismic force (kawano(2008)). The uncertainty effects on the dynamic response evaluation of the idealized offshore platform model with offshore wind energy production are discussed with wave force and seismic force in the present study. The seismic force is one of the most significant dynamic forces for the offshore structure with wind generation system, which has relatively heavy loads on the top of the tower.
Maejima, T. (Japan Oil, Gas and Metals National Corporation) | Uno, H. (Tokyo Electric Power Services Co., Ltd.) | Mito, Y. (Kyoto University) | Chang, C.S. (Kyoto University) | Aoki, K. (Kyoto University)
Pawar, Rajesh J. (Los Alamos National Laboratory) | Zyvoloski, George A. (Los Alamos National Laboratory) | Tenma, Norio (National Institute of Advanced Industrial Science and Technology) | Sakamoto, Ysuhide (National Institute of Advanced Industrial Science and Technology) | Komai, Takeshi (National Institute of Advanced Industrial Science and Technology)