Ocean Thermal Energy Conversion Plant to be Demonstrated in Okinawa

Keywords:　Environmental Technology　Manufacturing industry　

Japanese companies IHI Plant Construction Co., Xenesys Inc., and Yokogawa Electric Corp. announced on July 9, 2012, that they have jointly won a contract from Okinawa Prefecture for a fiscal 2012 pilot project to use deep seawater for electricity generation. Plant builder IHI, Xenesys, a specialist in thermal energy conversion technologies, and Yokogawa Electric, a provider of control and monitoring systems for plant facilities, will work together to demonstrate their ocean thermal energy conversion (OTEC) technologies in Okinawa.

The three companies will build a small-scale pilot facility by March 2013, and start testing it for its practical application using some of the deep sea water and surface water extracted by the Okinawa Prefectural Deep Sea Water Research Center in Kumejima Island.

OTEC utilizes the difference in temperature between cooler deep seawater and warmer surface seawater to generate electricity. The warmer surface water is used as a heat source to vaporize a low-boiling-point working liquid such as ammonia and drive a turbine. The vapor is then sent to a condenser where it is turned back into a liquid by the cooler deep sea water. This allows repeated use of the working liquid. OTEC is drawing attention as a technology most suitable for use in tropical and sub-tropical areas where there is a large difference in ocean temperature between the surface and deeper sea levels.