Cabinet Ministers Ishiba and Shimajiri visit Kumejima

IMG_8195On May 1, 2016 Minister of State for the National Strategic Special Zones Shigeru Ishiba and Minister of State for Okinawa and Northern Territories Affairs Aiko Shimajiri visited the Okinawa Deep Seawater Research Center and related deep seawater industries on Kumejima.

While Minister Shimajiri has visited Kumejima several times prior to her elevation to Cabinet level, it is the first time both ministers have visited in their current roles. After learning about the Kumejima Model at the ODRC, the ministers visited the Okinawa Ocean Thermal Energy Conversion (OTEC) Facility, as well as local industries including Point Pyuru Cosmetics, Kumejima Sea Grape Aquaculture, GO Farm Oyster Research, and the Kumejima Cooperative Kuruma Prawn Farm.  IMG_8273The Minister’s tour also marked an important day for us at OTEC Okinawa, being the 5000th visitor since our opening. These industries have taken advantage of existing deep seawater resources to create economically significant industries for Kumejima, however, they all are constrained by the limited capacity of the existing pipeline.

The Kumejima Model is an integrated system of deep seawater users that can lead to a community model for self-sufficient communities. In the future, Kumejima hopes to test the incorporation of Megawatt scale OTEC for power supply with other uses such as desalination for water so that the deep seawater resource is used efficiently. Testing the incorporation of these various industries and technologies at Kumejima’s small scale will allow for less expensive and more efficient use in other locations in Okinawa, Japan, and the world at large in the future.


After touring the facilities, both ministers also took part in a seminar hosted at the Gushikawa Community Center. The ministers spoke about their observances during the day, and Minister Ishiba discussed the difficulties in rural Japan such as depopulation. Both ministers stated the would “fully support Kumejima’s efforts.”

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IMG_7796On April 4th, Kumejima celebrated the opening of it’s new Learning Center, dubbed the “Jinbun Hall.” The center is a renewal of an unused family clinic building, designed to house students attending Kumejima High School from outside the prefecture. With the island population declining by an average of 91 people per year over the last 23 years (2119 total), the island’s board of education was forced to look at expanding student enrollment, or face having to close the school. With limited resources, the school for the first time, invited students from outside the prefecture to attend. Students stayed with host families during the year.

IMG_7699The success of the program and growing number of students from outside of Kumejima required an expanded space to house them. The new Learning Center is a four-story building that can house up to 24 students on two floors in 4-person rooms. The  first floor includes food-preparation facilities and the learning center, as space that will be available for educational related events and classes.

The ribbon cutting and facility name revealing ceremony was attended by local, prefecture, and national leaders.






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IMG_7695Kumejima has a new bus running around the island. The town is situated around the wetland preserve and mountains in the middle of the island. The Kumejima bus service provides routes around the island and to the airport. Starting in April, the new Kumejima Bus started operations. The sky blue bus is quite different than the previous yellow, and easily show’s off its most distinctive aspect, the new logo drawn by famous Japanese animator Hayao Miyazaki of Studio Ghibli. Miyazaki donated the mark to Kumejima in response to their support of children from Fukushima. The mark is now also the logo for GOSEA.




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Kumejima Ocean Energy Video

The Okinawa OTEC Demonstration Facility has been featured in the news, magazines, and TV, yet many of those sources can be hard to find after a little while. Now we’re pleased to share a short video with you that highlights not only Kumejima, but the Okinawa Deep Seawater Research Center (ODRC), and the OTEC facility. The video includes images and video from the construction of the ODRC in 2000 as well as photos of the construction of OTEC Okinawa! We hope you enjoy.




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Indonesian Delegation to OTEC Okinawa

DSCN1043_1At the end of March 2016 we welcomed a delegation from the Republic of Indonesia Coordinating Ministry for Maritime and Resources Affairs as they sought to learn more about Ocean Thermal Energy Conversion, Deep Seawater Use, and the potential for applying such technologies in Indonesia. With Indonesia’s proximity to deep seawater, warm surface seawater, large population, and numerous communities still lacking secure access to power and water, Indonesia has perhaps the largest potential for use of this clean and renewable technology in the world.

DSCN1044_1Kumejima’s 100kW-class OTEC facility provides visitors the opportunity to see the world’s longest running operational OTEC facility using actual deep and surface seawater up-close, and feel the temperature of the waters driving the power generation cycle. The Kumejima Model, which is the local answer to creation of a sustainable and self-sufficient community, is set to be an important step in realizing small-scale OTEC is not only technically possible, but economically practical as well. As deep seawater related industries on Kumejima already account for roughly a quarter of the local economy and there is existing demand for water, know-how in its use, and local support, the island is uniquely suited as a community testing ground to integrate the separate yet related fields involved in using deep seawater effectively.

DSCN1034_1It is our hope, that the delegation found their trip interesting and informative, and that what they saw here will help accelerate the adoption of renewable, base-load clean energy around the world.

As this financial year comes to a close, we thank the thousands of visitors who have come to Kumejima so far, and look forward to sharing OTEC Okinawa with more next year. If you haven’t seen our facility yet, we hope you will come for a tour.









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IMG_67362016年3月18日、株式会社ヒューマンウェブが4月以降に現在の研究施設を拡大することに伴い、地鎮祭を行いました。 同社は、首都圏を拠点に国内最大手のオイスターバーを経営、展開している企業です。


牡蠣は1時間に20リットルの水を吸い、吐き出して成長していくそうです。 海水の中には生活排水による汚染物質が含まれており、ノロウィルスもその一つに当たります。 しかし、海深くにある海洋深層水には、細菌等の微生物や水質を悪化させる有機物等の汚染物質が、表層水に比べて10分の1~100分の1と少ないことが分かっています。 同社も2006年にノロウィルスの流行を受け、風評被害で消費が落ち込んでしまった時期があったようですが、牡蠣の浄化施設を整備したり、ここ久米島でウィルスフリーの牡蠣の研究を行ったりと消費者へ安全な牡蠣を提供するため様々なことに取り組んできました。

今回、久米島町で取り組んでいる海洋深層水取水量の増量を見越し、世界初の陸上養殖での牡蠣の量産化を目指して設備を拡大することを決定。 地鎮祭当日は牡蠣も振る舞われ、大田治雄久米島町長はもちろん、島内外から海洋深層水関係者や関連企業の要人が多数訪れて祝賀ムード一色となりました。


沖縄のような温かい地域では生産が難しかった牡蠣の養殖が、技術が進み実現が近づくにつれ、海洋深層水の力に大きな可能性を感じずにはいられません。 今後更に様々な分野で多くの研究が進み、産業が拡大していくことでしょう。



On March 18, 2016 Humanweb broke ground for their Virus-Free Hatchery and Research Center on Kume Island. Humanweb is a large oyster bar company with stores around Japan selling raw, high-end oysters. Recently, noro-virus scares around the world has significantly damaged the popularity of oysters in Japan, when eaten raw. In a country famous around the world as the home of sushi, it may seem odd to visitors from Europe that most oysters are eaten cooked. To improve safety, Humanweb has utilized clean deep seawater at its distribution centers to clean its oysters before sending them on to their bars. Still, with oysters grown in the ocean there is always a perceived risk.
IMG_6752Since 2012, Humanweb has been researching the development of onshore oyster farming, hoping to have the world’s first fully land-based hatchery to grow-out system to ensure oysters are virus-free and safe for raw consumption. In order to reach this goal, Humanweb broke ground on a new state-of-the-art facility intended as the first step towards commercial capacity for oyster hatchery  and as a test-bed for onshore grow-out. Using deep seawater from the Okinawa Deep Seawater Research Center may soon provide the prefecture with an entirely new product as oysters are not currently farmed in Okinawa due to warm surface temperatures.

The ceremony on March 18th included consultants on the project, local deep seawater industry representatives, Kumejima Town Mayor Haruo Ota, and of course, oysters to enjoy afterward.

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Do You Fugu? A visitor to ODRC

IMG_0973The Okinawa Deep Seawater Research Center on Kumejima has now been operating for more than 15 years with both surface and deep seawater pipes. The deep pipes are open-ended, while the intake for the surface pipe has bars to keep out larger fish.

In both surface and deep water cases, there are strainers prior to the pumps so that any fish large enough to have issues with a pump will be kept away from it.  In the past, the ODRC pumps regularly turned off and on based on the demands of local industries and the center. Since 2013, however, the Okinawa OTEC facility now utilizes all remaining water for power production, and the pumps run 24/7, except in rare cases of maintenance at the ODRC.

Based on observations from maintenance personnel, it seems that only when the pumps stop do fish occasionally swim into the pipe intake. When the pumps are turned back on, the fish flow up to the strainer, where they can be safely removed for return to the ocean or for study. When the pumps run continuously, they seem to avoid the intake.

This month, during maintenance on the intake pit, we had a new visitor. This Fugu is quite large and a welcome visitor to the ODRC.

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琉球大学教育学部の皆さん ありがとうございました!


426 IMG_0792


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2016 ミス沖縄 OTEC視察



左から2016ミス沖縄 スカイブルーの奥濱 安奈さんと2016ミス沖縄 コバルトブルーの森田 久美子さんのお二人。




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On January 24th, the same cold front that fell through the Eastern United States and Europe, also brought unusually low temperatures and snow throughout the Japanese archipelago.  Until now, snow had only been observed in Okinawa Prefecture here on Kumejima, however, this time, measurable snow was also recorded on Okinawa for the first time, although it was only a little.

Between the afternoon of the 23rd and the evening of the 24th, the temperature on Kumejima fell 10°C. The temperature when the snow fell was less than 6°C (higher elevations on the island had lower temperatures than at the OTEC facility) with the lowest temperature recorded at the OTEC Facility of 5°C, the lowest temperature in 29 years.

With this unusual weather, we of course are interested in its affect on the sea temperature.

At the Okinawa OTEC Facility we record the incoming seawater temperature for both surface (15m) and deep seawater (612m).  We include that data in the graph above. The red line indicates the surface seawater temperature, the blue line is the deep seawater, and the green line is the air temperature for a week.

As you can see, even from the peak air temperature of 17°C, the seawater maintained its temperature of about 23°C, not even changing 1°C through the 10°C temperature drop.

The specific heat of seawater is about 4 times greater than air, and the specific gravity is about 800 times greater. When comparing the same volume, you will need 3200 times more energy to warm seawater 1°C than air. In other words, seawater stores vast amounts of heat energy. This resource is the source of the stable power produced by Ocean Thermal Energy Conversion.

This is also why the Okinawa OTEC facility can still produce power, even when it snows.

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