Dossier Océan et énergie - Énergie Thermique des Mers

Sommaire IOA News Letters

THE ACTIVITIES OF RESEARCH AND DEVELOPMENT ON DEEP SEA WATER UTILIZATION IN JAPAN (II)

Takayoshi Toyota, Toshimitsu Nakashima
Japan Marine Science and Technology Center

(continuing from vol.4, no1.)

  1. Effect of cleanliness of deep sea water on larvae

    Larvae of the Japanese spiny lobster, Panulirus japonicus, after hatching are called phyllosoma, which metamorphose to Puerulus after one year . Survival rate of Phyllosoma had been significantaly low. Phyllosoma was   reared both in surface water and in deep water in order to examine the effect of cleanliness of deep water. Survival rate at 120 days of age was 90% in deep water, and 14% in surface water. (Joint study between JAMSTEC and Tasaki Institute for Marine Biological Research, Tasaki Shinju Co. Ltd.)

  1. Production of substances for medical use

  1. Culture of phytoplankton

    Growth response of the diatom, Chaetoceros ceratosporum, to deep sea water was examined in continuous culture condition. Under the steady state, the percentage of utilization of nitrate was 47%, although the addition of EDTA plus Fe increased the percentage of utilization up to 100%. The results show evidence that the enrichment with chelator or available complexed iron enables more effective utilization of deep water for the enhancement of primary production.(JAMSTEC)

    The effect of various environmental conditions on £]-carotene production by Dunaliella salina in deep water were studied. Nitrate and Fe-EDTA were the best forms of nitrogen sources and Fe sources, respectively. Optimum culture conditions were examined. (Government Industrial Research Institute, Chugoku)

    Two species of microalgae [ (1) Porphyridium sp., (2) Nannochloropsis salina ] were cultured for two weeks semi-continuously, in an outdoor raceways pond circulated by a screw pump. The mean productivities of (1) and (2) were calculated at 2.66 and 5.20 g m-2 day-1, respectively. Through these experiments, significant contamination by other organisms was not observed. (Joint study between JAMSTEC and Chlorella Industry Co. Ltd.)

  1. Utilization of deep sea water for recovery of energy

  1. Water temperature control

    A temperature control system using warm surface water and cold deep water was developed .The system, consisting of a heat exchanger and a heat pump, decreased the energy consumption to 50-70% compared to that of a conventional system consisting of a boiler and refrigerator. The accuracy of the temperature control system was ±1 ¢J for the desired temperature. ( Joint study between JAMSTEC and Institute of Technology, Shimzu Corporation)

  1. Air-cooling for office

    The temperature of supplied deep water was about 12 ¢J all year round. This deep water flowed through pipes hanging from the ceiling of an office building for air-cooling. This study was successfully conducted. (Joint study between JAMSTEC and Institute of Technology, Shimizu Corporation)

  1. Desalination

    Two types of desalination¡@ systems (distilled and reverse osmosis) were examined. Temperature difference between warm surface water and cold deep water is advantageous to the distillation method. Cleanliness of deep sea water minimizes maintenance and lengthens the life of the reverse osmosis members. It is supposed to be economically feasible at places where there are few fresh water resources, i.e. special isolated islands. Desalination system by reverse osmosis is now successfully operating. Concentrated seawater, a by-product, is anticipated to be used for various use. (Joint study between JAMSTEC and Logistics Research and Development Center, Nippon Yuen Kaisha Ltd.)

  1. Development of supporting technology

  1. Water intake

    Deep sea water supply system for KAUL was constructed in March, 1989. Water intake depth was 320 m. Water intake volume per day was 460 m3. Inner diameter of deep water pipe was 125 mm and the length 2650 m. The pipe was made of high density polyethylene with steel wire armor. Biofouling inside the deep water pipe was not observed during two years after operation. Floating matter (fish, shrimp, star fish, man-made substances etc.) were pumped out about twice a month from a strainer set up prior to the pump. (JAMSTEC)

  1. Monitoring system for water quality and laboratory conditions

    Monitoring system for measuring water quality (temperature, salinity, pH and dissovled oxygen in supplied deep and surface water, and in the water in experimental tank) and laboratory conditions (water intake velocity, pump power, air temperature in laboratory building, etc.) were developed These data are monitored on CRT, and recorded on a floppy disk in every 5 minutes. (Joint study between JAMSTEC and Institute of Technology, Shimizu Corporation)

Prospect

We feel that the following are important in order to develop practical technology by use of deep sea water.

To research potential applications of deep water utilization.
To educate the public and gain support from the public.
To confirm the structure of research organization and good laboratory for experiments using deep water in order to engage a long term R & D effort.

JAMSTEC researchers are conducting a cooperative study on the construction of one more deep water pipeline at KAUL with the researchers of Kochi Prefecture.

Two prefectural governments (Kochi and Toyama) have a plan of fish-farming center by the deep water. In the plan, intake volume of deep water would be several thousands cubic meter per day.