Jul 22 2012

OTEC the Only Option for Japan

Published by under Student blog entries

Japan, unlike the United States, has incredibly limited on-shore space, and with the sun and the wind being intermittent, around 80% of Japan’s long term energy supply remains insecure. The country has never been largely reliant on fossil fuels and with the Tohoku earthquake, tsunami and nuclear disaster, nuclear power is an unattractive option. Even with little current, small salinity gradient resources, and major storms just off the coast, is the  ocean is Japan’s best option for sustainable energy for the future. Ocean thermal energy conversion (OTEC) in particular has been labeled “the only productive answer” for the country recovering and rebuilding after recent natural disasters and the falling economy that followed.

An OTEC Plantship design

OTEC was tested in Japan thirty years ago on Nauru by the Tokyo Electric Power company. The experiment was widely successful however a hurricane eventually wiped it out. Now, Japan looks at the success seen and considers using OTEC to power a plantship. This ship would graze along the coast, providing benefits in the upbringing of fisheries. Additionally, opportunities would be seen for the development of marine biomass plantations, which would produce biofuels at sea, electricity, and freshwater.

Platforms on the sea surface would harvest the energy, The water intake could be installed vertically, allowing pipes to be much shorter. Construction and operation costs in turn would be cheaper and damage to pipes less as they would float versus being cemented to the sea bottom.  In being pumped up to the at-sea “power plants”, cold water would retain its low temperature making net power generation far higher. The platforms could also be equipped harness sun and wind resources. Construction would require zero of Japan’s limited land space.

A demonstration facility test is set to be carried out in Okinawa Prefecture by three companies: IHI Plant Construction Co.,Ltd., Yokogawa Electric Corporation and Xenesys Inc. at a cost estimate of 500 million yen. The design is of 50kW nameplate capacity and should be complete by March 2013. The test claims to be the first OTEC demonstration conducted in an “actual ocean environment” with consideration to commercialization.

What remains a high priority is a protection mechanism for such devices to allow them to withstand storms. Otherwise, the large capital investment the technology requires would fail to be feasible lacking long term energy generation. Compared to other power plants, the construction cost of OTEC systems is high but once established fuel cost is negligible.


Japan as number four | The Japan Times Online. (1922, June 12). The Japan Times Online: News on Japan, Business News, Opinion, Sports, Entertainment and More. Retrieved July 22, 2012, from http://www.japantimes.co.jp/text/ed20120722a2.html#.UAwp9LR8C_g

Takahaski, P. (1924, May 11). Patrick Takahashi: The blue revolution is the optimal solution for Japan. Breaking News and Opinion on The Huffington Post. Retrieved July 22, 2012, from http://www.huffingtonpost.com/patrick-takahashi/the-blue-revolution-is-th_b_865378.html

What is ocean thermal energy conversion (OTEC)?. (2010, October 27). MarineBuzz. Retrieved July 22, 2012, from http://www.marinebuzz.com/2007/10/25/what-is-ocean-thermal-energy-conversion-otec/

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