Fig.6 shows the movement of tracer buoy thrown at the distance of 15 m from the machine on the depth of 3 m and 5 m. These results reveals that the density current generated from the machine was running continuously and widely in a velocities of more than 30 mm/s.
Regarding the water quality, Fig.7 shows the measurements of water temperature and turbidity made at 4 measuring points, distances of 5 m, 50 m, 100 m and 300 m from the machine. Fig.7 reveals a decrease of the surface layer temperature by 1 to 2 degrees C. and an increase of the water temperature within the intermediate layers by 1 to 2 degrees C. At the same time we could confirm that the thermocline, that had formed at a water depth of 2 to 4 m, had been eliminated.
Fig.7 also shows that turbidity reached a peak in the water depth of 3 m while the machine was out of operation. After starting the machine this peak disappeared and the water became more transparent.
This phenomenon reveals that the machine eliminated the rich phytoplankton layer by making the certain flow field, so it is expected that the machine works as a red tide preventer.
5. DOW UPWELLING MACHlNE
The deep ocean water (DOW) is the sea water located in the depth of more than about 400 m, and has three major property, "nutrient", "clean", "cold". Its amount is estimated more than 90% of total water on the globe, therefore, DOW is a huge unused resource remained in 21st century. In this chapter, the study to design the DOW upwelling machine is reported.
The purpose of the machine is to make the layer of sunlight in the sea very nutrient, to increase phytoplankton, and to make a rich fishing ground. The technology of the density current generator and the OTEC as the engine of the machine is studied and we propose the DOW upwelling machine shown in Fig.8.
