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MRMD-21B: Deep Ocean Water Utilization
ASSESSMENT OF ENVIRONMENTAL EFFECT AND FERTILIZATION OF SEA AREA USED DEEP SEAWATER
Masatoshi Hayashi, Tomoji Ikeda1, Ohtsuka Koji2 and Masayuki Takahashi3
 
1Kansai Environmental Engineer Center Co. Osaka, JAPAN
hayashi_masatoshi@kanso.co.jp
 
2Osaka Prefectual University
3Department of Systems Sciences University of Tokyo
 
It's intended in this study to establish the assessment method of environmental influence by discharging a large amount of deep seawater for producing electricity, and also to examine an adequate condition of deep seawater discharge, which will assist to fertilizing sea area.
 
At the intake gates of deep seawater and surface water pumping-up station, plankton entrainment was monitored once a month. Entrainment in the deep seawater was lower than that of surface seawater at every study station. Entrain plankton in the deep seawater station was mainly Copepoda spp., not found larvae of valuable animals. At the same place of biological entrainment research, 101〜102μM / kg of CO2 (seawater weight) was possibly emitted into air by pumping-up seawater. On the other hand, utilization of deep seawater may improve an efficiency of generating electricity. Taking this into consideration, although pumping-up deep seawater release CO2 into air, it brings out 11,000 ton CO2 / year of reduction by the improvement of generating efficiency.
 
As a method of minimizing environmental impact brought by discharge of deep seawater which was heated up at power station, it's adequate to diffuse at the offshore. 10〜15℃ of water temperature increase by using deep seawater can increase generating efficiency. Considering ±2℃ is a level in which changed water temperature bring biological impact, utilizing deep seawater at power station made diffusion zone smaller comparing to utilization of surface seawater. We studied a growth speed of phytoplankton by the process of mixing deep seawater and surface water. According to a higher ration of deep seawater, a growth rate tends to increase. Between a growth ration and total inorganic nitrogen and between a growth ration and water temperature were expressed numerical equation.
 
In the coastal area of Takaoka district including discharged area of deep seawater, Gelidium spp., became dominant and whose tendency was unchanged before and after deep seawater discharged. At the nearby discharge area, Mitsu district, Sargassium spp., was distributed showing an effect of deep seawater discharge. A relationship between seaweed growth and nutrient was examined by the process of mixing deep seawater and surface seawater. In the experiment using Gelidium sp. and Ulva sp., growth rates were maximum at around 60〜80% of deep seawater.
 
MRMD-21B: Deep Ocean Water Utilization
A PARAMETRIC STUDY ON POWER PLANT PERFORMANCE USING DEEP-SEA WATER FOR STEAM CONDENSATION
Masataka Kadoyu, Yuzuru Eguchi and Hirofumi Takeda
 
Central Research Institute of Electric Power Industry Abiko-shi, Chiba, JAPAN
kadoyu@criepi.denken.or.jp
 
Use of the deep-sea water would have beneficial effect on the plant efficiency because high vacuum is realized in the downstream of the steam turbine. Moreover, cleanness of the deep-sea water would prevent the pipeline from biologically fouling, with saving the maintenance costs. If these positive effects pay for both the initial investment required for the pipeline installation for the deep-sea water and additional running costs for pumping-up water from the deep sea, the use of the deep-sea water can be promising option as a method of power plant cooling.
 
In the present study, power plant performance is parametrically evaluated in applying deep-sea water to exhaust steam condensation as heat sink. A 600MWe fossil thermal plant is selected as a benchmark plant for the evaluation, and the plant performance and hardware requirements are calculated under various conditions using a heat balance analysis code.
 
The results show that, for an existing power plant designed for surface water cooling located in middle of Japan, annual electric power generation using the deep-sea water possibly increases by 1.4 point in comparison with conventional operation with the surface seawater. Especially in summer, it is expected the power generation can improve by 3.5 point at most in the north and middle of Japan.
 
If power plants are newly designed suitable for deep-sea water cooling, the heat transfer area can be reduced due to lower steam temperature in a condenser (Ts) or the pump capacity of the deep-sea water can be reduced due to larger the seawater temperature rise (DT) with smaller flow rate of seawater. To see the impact on the hardware design, heat transfer area and pump capacity requirements are calculated for a newly designed plant assumed in south of Japan. The result indicates that the heat transfer area requirement is the smallest under the condition of Ts= 38.5℃ and DT= 7.0℃, which is just 30% of the present design, though the pump capacity requirement is 1.4 times larger without improvement of plant efficiency. On the other hand, under the condition of Ts= 26.0℃ and DT= 12℃, 3.2 point of the total heat input to the boiler can be saved.
 
MRMD-21B: Deep Ocean Water Utilization
THERMAL ELECTRIC GENERATORS UTILIZING DEEP OCEAN WATER AS AN ALTERNATIVE ENERGY SOURCE
William Meyer1 and Maxwell Goldberger2
 
1Hawaii Environmental Solutions Volcano, Hawai'i, USA
williammeyer@hotmai.com
 
2Hawaii County Economic Opportunity Council Hilo, Hawai'i, USA
 
Temperature differential between warm tropical surface ocean water (26℃/79oF) and deep ocean water (40℃/39oF) was originally explored for possible ocean energy conversion (OTEC) in the 1980s. Thermal couple modules use dissimilar conducting metals that induce heat absorption at one junction and release it at the other, the Peltier Effect. An electrical potential is generated by increasing the temperature differential (rT) on the opposite ends of N and P polarized bismuth telluride semiconductors. A proto-type thermal electric generator utilizing deep ocean water as the cold source and solar parabolic mirrors as the heat source was constructed at the Common Heritage Corporation. The thermal electric generator produces an effective rT of 300℃ with an electrical output of 1 kilowatt. A small reservoir of oil, heated by solar mirrors is plumbed as the heat source to allows the system to maintaining electrical output during non-solar hours. The system is estimated to produce electricity at a cost of $0.15US/kilowatt/hr.
 
Although less efficient than current fossil fuels and other energy production systems, the DOW thermal electrical generator compensates for this factor in cost savings with no maintenance requirements due to a lack of moving parts, no exhaust issues and no fossil fuel dependency. Localized private thermal electric modular systems can be substitutes for centrally located municipal electrical generators and additionally reduce transmission infrastructure costs.
 
MRMD-21B: Deep Ocean Water Utilization
THE ADVANTAGE OF OTEC AS THE ENERGY SOURCE FOR OCEAN NUTRIENT ENHANCER
Takayuki Watanabe1, Kazuyuki Ouchi2, Toshio Yamatogi3 and Sadayuki Jitsuhara1
 
1Xenesys Inc. Tokyo, JAPAN
 
2Ouchi Ocean Consultant, Inc. Karuizawa Nagano Pref., JAPAN
 
3Nakashima Propeller Co. Ltd. Okayama, JAPAN
 
For the purpose to make a fishing ground in the sea by increasing the primary production, the Ocean Nutrient Enhancer (ONE for short) which raises the nutrient-rich Deep Ocean Water (DOW) and discharges it into the euphotic surface layer has been studied. To establish the concept of ONE, various kinds of the requisite technologies were evaluated from the viewpoint of proposing the extremely new type machine that we have never had before. Especially a choice of energy source for operating the ONE is primarily important to create its concept and outline.
 
The feasibility study on the energy source was carried out in order to establish the prototype of ONE. The result of study was that the most suitable energy system for the ONE is the combination of Ocean Thermal Energy Conversion (OTEC) as the main engine and Diesel Engine as the auxiliary engine. This choice can enjoy not only using the property of DOW's low temperature but also adopting submerged floating structure whose performances in the rough sea is very excellent.
 
MRMD-21B: Deep Ocean Water Utilization
POSSIBILITIES OF CREATING NEW FISHING GROUNDS USING DEEP SEAWATER
Sadamitsu Akeda1, Nobuo Takaki1 and Kazuo Iseki2
 
1National Research Institute of Fisheries Engineering, Fisheries Research Agency Ibaraki, JAPAN
akeda@fra.affrc.go.jp
ntakaki@fra.affrc.go.jp
 
2National Research Institute of Fisheries and Environment of Inland, FRA Hiroshima, JAPAN
kiseki@fra.affrc.go.jp
 
In 1989, the first deep seawater intake facility in Japan was built at Muroto for experimental research. Since then, research and development activities have been making rapid progress toward the use of deep seawater. From 1998, in consideration of the sanitation management of fishing ports, it has been possible to build deep seawater intake facilities. Such facilities with daily capacity of several thousand tons are constructed for production of drinking water and foods, seed production, aquaculture, thalassotherapy and so on, at Muroto, Shin-minato, Nyuzen, Namerikawa, Kume-Island. Yaizu and Miura. Japan's use of deep seawater is responding to public demand for saving energy, resource conservation and global warming countermeasures to utilize the special features such as stable low temperature, cleanness and nutrient content. For improvement of economical efficiency and multiple gradational purposes, the technology is being developed to utilize deep seawater to cool electric power plants, and to use massive amounts of deep seawater used as coolant. Part of technical development involves the use of deep seawater as fertilizer to help make coastal areas more productive. Upwelling areas are gaining attention as areas of high fisheries production. R&D has begun to pump massive amounts of deep seawater, and to discharge it in the photic zone to raise primary production, in order to create artificial upwelling fishing grounds. Although there are differences in the regions where water is pumped and discharged. In common, all R&D activities are related to fertilize maritime regions.
 
This paper will report on the state of and issues concerned with the utilization of deep seawater for the purpose of fertilizing maritime regions.







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