Japan: OTEC to cut fuel use

A Pacific media group received a tour of the experimental OTEC plant in Kumejima, Japan that is using deep sea water to produce energy and to support various businesses. Photo: Giff Johnson
A Pacific media group received a tour of the experimental OTEC plant in Kumejima, Japan that is using deep sea water to produce energy and to support various businesses. Photo: Giff Johnson


Years of painstaking research into alternative energy options in Japan have produced working prototypes that could lead to a large-scale reduction in use of fossil fuels in Japan and Pacific islands.
As countries of the world prepare to convene in Paris at the end of November for a pivotal climate action summit, officials in Japan say ocean thermal and hydrogen energy products are moving beyond the experimental stage and will soon be making an important contribution to clean energy production in Japan and beyond. The north Pacific governments in the Marshall Islands and Palau have both expressed interest in ocean thermal energy to reduce their dependence on diesel-powered electricity.
The use of deep ocean water to produce energy is “on the brink” of expansion, said Benjamin Martin, the international relations coordinator for the Deep Sea Water Utilization and Ocean Thermal Energy Project (OTEC) on Kumejima, near Okinawa, Japan. Similarly, Toshiba Corporation has ramped up its research and development work on hydrogen energy, opening a showcase research facility at its main Fuchu Complex in Tokyo, while Toyota is building an estimated 700 hydrogen-powered fuel cell vehicles this year, with plans to increase to 3,000 a year by 2017.
Although demonstration OTEC power facilities have been in operation in Hawaii and Japan for decades, the high cost to build a large plant has bottlenecked expansion. Kumejima Mayor Haruo Oota is promoting a Kumejima Model that integrates expanded use of OTEC power to reduce carbon emissions while using the nutrient-loaded and cold deep ocean water to support a wide array of industries including agriculture, aquaculture and cosmetics production. A key message from officials involved in developing OTEC in Japan is that use of deep sea water beyond just providing electricity is critical to making OTEC financially viable.
“If we are successful with OTEC, we can become self-sufficient in energy use,” Oota said, adding that they see the OTEC and its business applications as a model for export.
Although the OTEC facility and pipe capacity at Kumejima is limited to 10,000 tons of deep sea water daily, it is supporting prawn, sea grape and other aquaculture products, cosmetic production, and vegetable growing that is generating $20 million annually for businesses associated with the research facility, Martin said. “But production is tied to the capacity of the pipeline,” he said, adding that the existing businesses “have grown up around access to deep sea water” that is largely bacteria free and cold. Cold water circulated in pipes under plant beds speeds growth time for vegetables, while the clean deep sea water offers a safe environment for growing marine products, Martin said.
The high cost to expand the pipeline to increase deep sea water availability to 100,000 tons daily “is why we need to develop the Kumejima Model to pay for it,” said Martin. It is estimated to expand deep sea water use to 100,000 tons daily will require an $80 million investment in the pipeline.
The aim is to see business expansion so that deep sea water is used multiple times, generating revenue to cover the high cost of installation, which cannot be recovered by electricity production alone.

Read more about this in the November 6, 2015 edition of the Marshall Islands Journal.

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