In this paper, we propose the Deep Ocean Water (DOW) Upwelling Machine which is driven by the Ocean Thermal Energy Conversion (OTEC) for the purpose to increase the primary production in the stratified sea area of low latitude, so called "the sea of desert". In the area, there are very little nutrients in the surface layer of the sea where photosynthesis can be done by phytoplankton. To increase the primary production in the sea area, the machine upwells the nutrient-rich DOW and diffuses it very widely in the layer of sunlight by using a phenomenon of the density current which is driven by the gravity. The study of the effect and feasibility of the machine is carried out and it seems very significant.
In a stratified low latitude ocean area, the surface layer of the sea is warmed up by the sunlight and the high temperature air, and there is no vertical circulation between the warm surface layer and the cold bottom layer. Therefore, the sea of the low latitude area is always stratified with the temperature and density. The mankind, wishing the sea of fertility, hopes the increase of primary production in the layer of sunlight where the photosynthesis can be done by the phytoplankton. But the primary" " production, in the stratified sea area is very little, because the, deep ocean water which includes very much nutrient-salt such as nitrogen and phosphorus etc. does not upwell to come in the layer of sunlight. But we have some exceptions, for example in the sea of offshore Peru, a large amount of upwelling is occurred by the steady wind, so that the sea area is one of the richest fishing ground in the world and the water temperature in the surface is lower than another equatorial sea.