[Brief translation]
On March 31, Mr. Nobuyuki IDEI, former Chairman of Sony, visited Saga University to inspect power generation facilities of OTEC, which has been developed under the cooperation between a venture company of Xenesys Inc. and Saga University. Mr. IDEI, who has been stating "21st century will be an era of water", was interested in their technology and assumed Executive Advisor of Xenesys Inc.
OTEC is a power generation system, which uses temperature difference between surface seawater of 3-5m depth and deep seawater of 800-1000m depth. OTEC is now positioned as one of natural energies which do not use any fossil fuel and emit any CO2. Ammonia working fluid in a pipe is vaporized and expands by surface seawater of approx. 25℃, and then the ammonia vapor drives turbines to generate electricity. After that, the vapor is liquefied by deep seawater of approx. 5℃ to be used again. OTEC repeats this cycle to generate power.
Basic principle of OTEC was already invented in 1881, though, it had been generally accepted that OTEC as power generation facility was difficult as all the electricity generated by OTEC was consumed as energy source within the facility.
Ph.D. Haruo UEHARA, Professor of Saga University and Chairman of the Organization for the Promotion of Ocean Thermal Energy Conversion (non-profit organization), demolished this theory. He started a research on OTEC in 1970s and succeeded in developing a highly efficient heat system in 1994. He named the system as "Uehara Cycle".
Mr. Kiminao Satomi, who had been running a company of manufacture of machinery of brewing sake, was attracted to the technology and established a company "Xenesys Inc." with the aim of realizing commercial application of the technology.
The end of the year 2003, Xenesys built a demonstration plant with power generation capacity of 30 kW at Saga University, and in November 2007, they constructed a manufacturing facility in Imari-shi, Saga Prefecture. Xenesys has been assuredly carrying on the preparation to realize their commercial application.
From the standpoint of the commercialization, another system which uses waste heat of 100 - 150℃ from factories may be faster than ocean thermal energy. As the temperature difference between waste heat and seawater is large, huge amount of energy can be obtained through applying this system. Reutilizing remaining waste heat after the power generation, fresh water can be produced efficiently by using a plate type heat exchanger developed by Xenesys. Such power generation system integrated with desalination system is called hybrid system.
While various power generation costs are rising due to oil price soaring, cost competitiveness for OTEC, which do not need fossil fuels, is being boosted under the influence. Companies in the Middle East, which suffer chronic water shortage while being benefited by a rise in oil price at the same time, evaluate OTEC as one of natural energies.
According to Dr. Jitsuhara, Senior Managing Director of Xenesys Inc., interest to OTEC has been rapidly increasing since 2007.