Economic and environmental evaluations for multi-purpose utilizations of deep ocean water in Hateruma Island, Japan

The aim of this paper is to propose multi-purpose DOW utilization systems with enough capacity of ocean thermal energy conversion (OTEC), which can cover the total power of an isolated island as a renewable infrastructure, and to evaluate their economic feasibility and environmental impact focusing on reduction effect of carbon dioxide. Hateruma Island in Okinawa Prefecture, Japan was decided as a model site, because this island has suitable population for the present concept, and has some geographical advantages for OTEC. The results showed that the total net profit of the model becomes -170 million Japanese Yen (JPY), and the potential of carbon dioxide reduction is 3,880 t-C/y. Considering the price of CO
₂
emission is now less than 1,000 JPY per t-CO
₂
(e.g. EU market), the reduction of CO
₂
emission of the proposed model is too small. Therefore, we need to improve the economic efficiency (e.g. adding more profitable business), and to get some government subventions.