RIASSUNTO
ABSTRACT
This paper presents a review of researches on environmental impact assessment for pumping-up and discharging deep ocean water, which was performed from 1999 through 2003 as a part of a national project organized by the New Energy and Industrial Technology Development Organization (NEDO). In this study, 13 investigation subjects were selected for the environmental impact assessment for large-scale deep ocean water utilization. Some results of the major subjects, such as CO2 emission, biological entrainment and impingement, physical/chemical water quality, eutrophication, phytoplankton growth, red tide occurrence and seaweed growth including seaweed bed recovery are shown in this paper.
INTRODUCTION
Deep ocean water (DOW) is cold, nutrient-rich and pathogen-free seawater found at depth of several-hundred meters or lower. The DOW has attracted special interest as a renewable resource for energy and marine primary production (Fast, 1991), and also been focused as the useful material for fresh water production, air conditioning, refrigeration, and so forth (Van Ryzin and Leraand, 2000). The multiple productions based on this enormous renewable resource may result environmental sustainability and economic viability (Daniel, 1992).
In Japan, several DOW utilization facilities are operated by research laboratories (Otsuka, 2001). Various DOW applications and their integrated systems are investigated in these facilities. In addition, the pumped-up DOW is commercially distributed, and used for many products, such as drinks, foods, medical and health care uses, cosmetics, etc. Two national DOW projects for large-scale (105~106td-1) applications, which were driven by the New Energy and Industrial Technology Development Organization (NEDO) and the Marino-Forum 21 (MF21), have recently been operated (Kadoyu, Eguchi and Takeda, 2003; Takahashi and Ikeya, 2003). The NEDO project focuses on the optimum design of integrated DOW utilization systems for cooling steam-power plant units (Kadoyu, Eguchi and Takeda, 2003).