September 2, 2003

Deep Ocean Water for Consumer Products and Mariculture

Deep ocean water (DOW) is cold, nutrient-rich and pathogen-free seawater at several hundred meters or deeper below the ocean surface. It is now being used in a few countries for energy, drinking water and food resources. The DOW attracted special interest as a renewable resource for ocean thermal energy conversion (OTEC) more than a century ago by a French engineer. In recent years some new OTEC research projects have started in Asian countries for the generation of electric power and drinking water.

These days, demand for the DOW has grown for consumer products and mariculture. The use of nutrient-rich DOW for a land-based mariculture was first conducted in the U.S. Virgin Islands in the late 1970s. The experiments demonstrated that the utilization of the cold and nutrient-rich DOW increases the growth rates of microalgae, seaweed, fish, shellfish, lobsters and more. Encouraged by the results, Japan started research projects on open-ocean fertilization with the DOW. On-site DOW discharging tests for open-ocean fertilization were carried out at Toyama Bay, Japan in the late 1980s, and a new-type ocean nutrient enhancer was installed at Sagami Bay in 2003.

Since the 1990’s, Hawaii facilities pump up over 200,000 tons of DOW per day, producing many commercial-based DOW applications. Kochi DOW Laboratory, Japan’s first DOW research center established in 1989, has investigated fundamental water quality, fisheries applications, air conditioning, and microalgae productions. Distribution of surplus DOW to private companies started in 1995 and led to the development of many consumer products such as bottled water, liquor, salt, tofu, pickles, bread, dry fish, health care goods, cosmetics, etc. The distributed DOW is also used for medical treatments, such as for allergic dermatitis. More DOW research and utilization facilities are now in operation, and over 20 facilities are planned in Japan.

Japan’s national research project for large-scale DOW applications focuses on integrated DOW utilization systems with DOW cooling for steam-power plants. Another project, a prototype artificial upwelling machine named “TAKUMI”, has been installed at Sagami Bay for the enhancement of marine primary production. Taiwan and Korea are now investigating DOW applications, as well.

Six papers on the DOW upwelling projects and progress from Japan and Taiwan will be presented at The 5th ISOPE Ocean Mining Symposium ¾ ISOPE OMS-2003, Tsukuba, Japan, September 15-19, 2003. For the symposium program and other information, click on www.isope.org or email to info@isope.org.

Koji Otsuka, ISOPE Member