Kazuyuki Ouchi

Concept Design for Offshore DOW Platform as Infra-Structure of Isolated Island

DOW (Deep Ocean Water: The sea water below 200m depth) which has three major characteristics, Low Temperature, Rich Nutrient and Very Clean, is expected as a future renewable resources in the ocean. Toward the era of environment and low carbon, utilizing the ocean renewable resource is absolutely important because the land base resources are now peaking out. In order to making use of DOW effectively and economically, multi-purpose utilizing of DOW is recommended because it has many aspects of characteristics and advantages. First, Electric Power generation by OTEC (Ocean Thermal Energy Conversion) is carried out using the difference of water temperature between the cold DOW (5°C) and the warm surface water (25°C). Second, a fresh water generation by a desalination of the sea water is carried out using residual difference of temperature after OTEC operation. Third, the DOW after discharging cold temperature in the heat exchanger of fresh water generator is scattered into a photosynthetic surface layer in the sea and its nutrient enhances primary production of the sea and eventually make a rich fishing ground. Forth, Lithium and some other rare metal are absorbed from DOW by putting special filters in the continuous large quantity flow of DOW. In this paper, the multi-purpose DOW platform which generates the electric power, the fresh water, the fishes and the Lithium from only DOW and surface water is proposed as a supplier of infra-structure for an isolated island. Technical and economical feasibility study is carried out and the result is that the enough sized multi-purpose DOW platform is very feasible for the forthcoming environment era.Copyright

Ocean Nutrient Enhancer: Creation of Fishing Ground Using Deep Ocean Water

The project to create the fishing ground in the open ocean by rising Deep Ocean Water (DOW) and discharging it in the euphotic layer where photosynthesis can be done by DOW’s rich nutrient salt has been carried out since April 2000, sponsored by Japanese Government Fisheries Agency and Marino-Forum 21. The name of this machine is called Ocean Nutrient Enhancer (ONE for short). As the output of the first year research which includes tank tests, computer simulations and feasibility studies, following outline of the ONE’ concept is proposed. • Rising DOW of 500m depth and 500,000m3/day with the special impeller which makes density current in the euphotic region. • Power for driving the impeller is supplied by OTEC (Ocean Thermal Energy Conversion) engine using a cold characteristics of DOW. • Adopting the configuration of submerged spar type as a floating construction to work safely and continuously against the rough sea. • Upending of the riser pipe is considered for the reliable and cost-effective setting up operation. From the above research, the ONE’s effectiveness is confirmed significantly.© 2002 ASME

Scale model experiment on density current in Sagami Bay

The project to create a fishing ground in the open ocean by raising deep ocean water (DOW) and discharging it in the euphotic layer as a density current where photosynthesis can be done by DOW rich nutrient salt has been carried out since April 2000, sponsored by Japanese Government Fisheries Agency and Marino-Forum 21. The name of this machine is the caged Ocean Nutrient Enhancer (ONE for short). The outline concept of ONE is: raising DOW of 500 m depth and 500,000 m/sup 3//day with a special impeller, which also sucks the surface water in order to make a mixed water of proper density. Discharging the nutrient-rich mixed water continuously and making a density current in the euphotic region. Increasing the phytoplankton (primary production) in the layer of the density current increasing fishes in the above sea area. Power for driving the impeller is supplied by OTEC (ocean thermal energy conversion) using the cold characteristics of DOW. To confirm the characteristics of the density current in Sagami Bay where the real sea experiment is scheduled, a scale model experiment of 1/200 in a continuously stratified salty water tank was carried out. The suitable discharge velocity to maintain the rich nutrient in the density current layer was researched in the way of 2 and 3 dimensional flow experiments. In conclusion, the thickness of the layer of density current in Sagami Bay in the summer season was estimated to be about 12 m, and the thinning ratio of DOW in the case of using a 3 dimensional ring nozzle is from 3 to 4 times. These results are very valuable for designing the ONE that is scheduled to be set up in Sagami Bay in the year 2003.

Hydrogen generation sailing ship: Conceptual design and feasibility study

We examine the concept and feasibility of using an ocean sailing ship as a massive, mobile energy collection device. The ship supports multiple retractable rigid wing sails, large diameter water turbines, and an electric power generator fitted with a water electrolysis plant to generate hydrogen. The hydrogen is subsequently stored in a more stable condensed liquid phase by reacting with toluene to make methyl-cyclo-hexane (MCH) in an on-board reactor. Our results show that the ship is able to both generate and transport low-cost hydrogen-based energy, offering a new avenue toward the eventual replacement of fossil fuels.

An Application of Ocean Mining Technology: Deep Ocean Water Utilization

Deep ocean water (DOW) is seawater found at depth of several-hundred meters or lower, and has attracted special interest as one of the renewable resources with great potential, since large amount of cold and stable DOW is renewed in thermohaline circulation such as the great global conveyer. DOW has also been focused as important resource for enhancing marine primary production because DOW contains much inorganic nutrients, such as nitrogen, phosphorus, and silica. In this chapter, we describe fundamental features of DOW and discuss the importance of utilization of DOW, from the viewpoint of sustainability of global environment. We also introduce several technologies of DOW utilizations, such as ocean thermal energy conversion (OTEC), air conditioning, fisheries application, agricultural application, freshwater production, and so forth. Finally, we propose a multipurpose DOW complex float, which generates electric power, freshwater, rare metal and fish ground from only DOW and surface seawater as a sustainable infrastructure.

Numerical analysis of the performance of the density current generator for energy-saving shrimp culture

The intensive cultures have expanded rapidly due to their good productivity. However, the sustainability of intensive shrimp culture is increasingly being questioned. Many problems like disease due to virus, excessive nutrient enrichment, and hypoxic condition around the bottom soil are reported in the intensive culture ponds. In order to solve such problems, the water quality of the culture pond is managed every time. A paddle wheel aerator is generally installed per 500 to 1000 m2 in the intensive culture pond. The purposes of the paddle wheel aerator are to supply oxygen in hypoxic water and to transport sludge to the center of the pond. However, a paddle wheel aerator requires much electric power and sometimes occupies the cost more than half of the sales of shrimps. The present study proposes the use of the density current generator, which sucks water from upper and lower layers, and pushes out the mixed water in the middle layer. The purpose of the present study is to analyze numerically the performance of the density current generator for energy-saving shrimp culture. The numerical model is MEC (Marine Environmental Committee) ocean model, which contains the numerical simulation tool of hydrodynamic and ecosystem processes. Aerobic and anaerobic organic matters are considered in the benthic ecosystem model. The vertical profile of water current velocity around a paddle wheel aerator and a density current generator was given from the observations. The effects of shrimps are given as constant values assuming that the density of shrimps is around 40 individuals per square meter, that the feed conversion ratio is 2.5, and that the emission of wastes from shrimps is divided equally into organic and inorganic matters. As a result of numerical simulation, the basic environment in the shrimp culture pond was reproduced when paddle wheel aerators are installed in the pond. Then the performance of paddle wheel aerators and density current generator was compared based on the concentrations of dissolved oxygen and sludge. Sludge can be transported by density current generator using less energy. However, sludge is not eliminated from the pond when the density current generator is used, resulting in requiring more oxygen in water. The present study is the preliminary one to predict the performance of the density current generator. The future study includes the feasibility study in the actual or scale pond, comparing the results of numerical simulation and field investigation.