New Ocean Thermal Energy Conversion (OTEC) Plant in Hawaii

Makai OTEC © Makai Ocean EngineeringSince 2013 OTEC Okinawa has been the only fully operational OTEC facility in the world. What we mean by fully operational is using deep seawater and surface seawater to create power and connect it to a grid. Other lab-sized OTEC plants operate around the world using heated or cooled water to simulate actual conditions in order to test components. Saga University has one such system in Japan. Like any system, lab testing can only get you so far. The unique properties of seawater require testing in the elements in which larger scale emplacements will actually operate. We’re happy to welcome Makai Ocean Engineering’s facility to the small group of OTEC facilities in operation.

OTEC in Hawaii

OTEC isn’t a new idea in Hawaii. Any history of OTEC will point you to Mini-OTEC or the 210kW open cycle plant in the 1990s.  What makes the Makai plant (or ours for that matter) relevant? Makai’s tower was originally built for heat exchanger testing. As one of the components of the OTEC cycle that can be optimized (and thus reduce costs), heat exchangers require the most intensive study before large-scale production. With the addition of a turbine and control systems, the addition of power production capacity adds value to the initial research investment and marks a milestone towards commercialization.

Makai OTEC © Makai Ocean EngineeringOn August 21, 2015 Makai Ocean Engineering celebrated the beginning of power production at their facility at an event on site. Attended by the Governor of Hawaii and other dignitaries, the guest list also included Professor Ikegami from Saga University, representatives from Okinawa and the companies involved in OTEC Okinawa, and representatives from Kume Island including the town mayor. This facility makes Makai’s OTEC plant the largest in the world, which makes sense since the Natural Energy Laboratory of Hawaii Authority (NELHA) operates the world’s largest capacity deep seawater intake pipelines. According to Makai, the facility will “deliver OTEC power to the grid and serve as a test bed to reduce the cost and improve the performance of OTEC technologies.”

Makai OTEC © Makai Ocean Engineering

Producing power and connecting it to the grid will provide valuable information on the effects of seasonal changes on power delivery, allow refinement of control systems, and most importantly raise awareness of the viability of OTEC as a base load renewable power source.  Based on the wide media coverage so far, they’ve already succeeded.

The Next Step

Makai OTEC © Makai Ocean EngineeringWhile both the OTEC Okinawa and Makai OTEC demonstration facilities are providing valuable data and critical research infrastructure they are still only demonstration facilities. OTEC relies on economies of scale, extracting a small amount of heat from the vast solar energy collector that is the ocean. Since such large commercial facilities require significant capital costs (offset by low maintenance, no fuel, and low running costs), prior to full commercial 10MW+ plants, a MW class plant is needed to refine large-scale equipment production (reduced cost for that larger plant), control systems (no OTEC plant in the world yet has a dedicated deep seawater pipeline), our understanding of the environmental impact (like lab testing, models only go so far), and to prove the technology is economically, politically, and environmentally viable.  In the meantime, we will continue to provide the data needed to improve OTEC components and systems.

We applaud Makai’s hard work in developing OTEC and we look forward to the continued cooperation between Okinawa and Hawaii and Hawaii County and Kume Island.

–All photos courtesy of and © Makai Ocean Engineering. Used with permission.

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台風9号 沖縄に接近中





Typhoon 1509 (台風1509)

As you may have heard, three typhoons are currently south of Japan. Typhoon 1509 is quickly approaching Okinawa and is expected to hit momentarily (about noon on  7/9/2015). While winds are picking up, we still have blue skies and sunny weather. Kumejima’s infrastructure is built to withstand strong weather, so even though this typhoon may be as high as a level 4 when it reaches us, we do not expect any major issues.

Although it is difficult to time such natural occurrences, we expect to close the Research Institute and the OTEC facility through Friday afternoon, so if you were hoping for a tour, we’ll hope you understand and catch us after the wind blows through.


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第9回久米島海洋深層水の日2015 イベント開催


去る平成27年6月14日(日)に、第9回久米島海洋深層水の日 Sea Water Dreem フェスティバルが開催されました。



また、今年は㈱ヒューマンウェブ 生産開発本部の鷲足本部長による「海洋深層水を活用した世界初!2つの取組み~カキの陸上養殖と浄化システム~」、久米島町プロジェクト推進室の中村室長による「航海興国・久米島モデルの実現にむけて」と題した特別講演が行われ、久米島の海洋深層水を活用した新たな取り組みが紹介されました。


2015 Deep Seawater Dream Festival 

IMG_0095640Deep Seawater on Kumejima is brought up from 612m below the surface of the ocean. Kume Island celebrates with a Deep Seawater Day on 6/12 and the Deep Seawater Dream Festival as close as possible.  This year, the festival will take place on June 14, 2015. Just two years ago we celebrated the start of OTEC Okinawa at this fun event and we look forward to another great showcase of the many products made with Deep Sea Water.

Update: We had great weather for this year’s festival which made meeting the many visitors even more fun.  Guests cooled down with snowcones and a bamboo shoot full of deep seawater and mozuku!

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Cabinet Level Visit to Kumejima’s OTEC Facility

On May 23, 2015 Minister Yamaguchi (Minister of State for Okinawa and Northern Territories Affairs) visited Kumejima to visit local deep seawater industries including the Ocean Thermal Energy Conversion Demonstration Facility here. With his busy schedule, his visit was necessarily brief, however, he was able to see the OTEC facility and industries such as Kuruma Prawn Fisheries and Sea Grape farming. Minister Yamaguchi braved unusually strong winds and rain to get an up-close view of the OTEC facility with explanations from engineers and Dr. Yasuyuki Ikegami from Saga University’s Institute of Ocean Energy.

Most renewable energies require large capital investments that are offset by future running cost and maintenance savings. In the development phase, initial capital costs are nearly impossible for private companies to front on their own. Support from local, state, and national government agencies are critical to developing clean energy for the future. With high level interest in OTEC and their related industries, Japan can continue to develop this interesting and potentially critical technology for the future.

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Credit: Top photo courtesy of Mr. Kanai, others courtesy of Saga University.

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第1回再生可能エネルギーワークショップ開催 in 久米島         First Renewable Energy Workshop



For the Past Several years alternating conferences Have taken place on Kume Island and Hawaii, focusing on Renewable energy Development. 2014 marked the Fifth year of THESE conferences with a new theme hosted by the New Energy and Industrial Technology Development Organization ( NEDO ) and Taking place on   Kume Island . The two-Day First Renewable Energy Workshop focused on Bringing Japanese and US companies and Government Together to Talk About the Potential for cooperation in Renewable energy fields.

1日目 平成26年10月30日(木)

Day 1 – October 30, 2014IMG_1753

主催者のNEDO新エネルギー部 渡邊統括主幹 、共催者の沖縄県 玉城産業振興統括官、来賓の在沖米国総領事館 Jennifer Nichols主席領事、久米島町 大田町長のあいさつの後、日米の再生可能エネルギーの取組状況について、渡邊氏とNichols氏より報告がありました。

また午後は、再生可能エネルギー(PV、風力、BIO他)及び系統技術セッションが行われ、日本サイドからは沖縄電力㈱、㈱沖創工、㈲沖縄小堀電機、㈱アイ・シー・エスの4企業、米国サイドからハワイ大学、Ter Viva.Inc、US Navy Ashore Renewable Energy Program(公的機関)、ハワイ郡政府の4機関がプレゼンテーションを行い、その後SEEDSとNEEDSをマッチングさせるためのビジネスセッションに移りました。

The first day of the workshop kicked off at 13:00 with speeches and welcomes from the host NEDO and co-host Okinawa Prefecture. Guest speakers from the American Consulate General in Naha, Kumejima Town Mayor Haruo Ota, and Dennis Teranishi from PICHTR spoke as well.

Covering the current status of renewable energy in Japan and the United States were representatives from NEDO and the US Department of Energy. After a break, the second session was a chance for businesses and organizations to showcase their progress in developing renewable energy including PV, wind , Grid, and other factors, followed by an open discussion and matching for potential future cooperation.


2日目 平成26年10月31日(金)

Day 2 – October 31, 2014


米国からPICHTRのDennis Y.Teranishi President & CEOによる「PICHTR’s Clean Energy Innvation Programs to Support Japan and Hawaii」、日本から佐賀大学の池上康之教授による「佐賀大学における海洋エネルギー開発の取り組み」と題した特別公演がありました。


The second day of the workshop kicked off with special lectures by Mr. Teranishi of PICHTER and Professor Ikegami of Saga University as they shared current efforts to develop clean energy around the Pacific.

The afternoon offered a chance for Japanese and US businesses to share clean energy technologies and talk about ways of working together. On the Japan side, Xenesys Inc spoke about the development of heat exchangers and the OTEC facility on Kume Island, Kobe Steel presented on their specially designed titanium plating for increase heat transfer, as well as their research into improved cooling exchangers as well, Japan Marine United spoke on their floating structures, and finally IHI presented on their tidal energy work. IMG_1835For the US side both Makai Ocean Engineering and the County of Hawaii presented on the multiple opportunities for new research and growth at NELHA. We were happy to hear Makai confirm that they have received delivery of their 105kW turbine and plan to connect to the grid in the first part of next year. We congratulate them on their efforts and look forward to continued development and distribution of demonstration facilities.  Both sides also discussed the possibility of working together to ensure OTEC continues to scale up, with several intriguing ideas that are encouraging for the future.


Finally, several of the local businesses using deep sea water on Kume Island presented about how they use deep sea water to create their important segment of the local economy.


IMG_1870With the end of the conference, visitors were invited to tour the operational OTEC facility on Kume Island and the many industries using deep sea water. Saga University’s Institute of Ocean Energy’s new satellite desalination demonstrator was also in operation to show how new techniques can harness the benefits of OTEC power and raw seawater to create clean drinking water at relatively low cost. This desalination project is the first time water from the OTEC facility on Kume Island is being used directly. One of the main tenants of the Kumejima Model is to increase economic efficiency by utilizing the benefits of Deep Seawater to their full potential. With continued research, support, and new projects such as the IOES desalination facility the future looks bright.


久米島-ハワイ郡 姉妹都市提携3周年記念 歓迎交流会

The Third Sister City Agreement Celebration




One of the highlights of the yearly meeting between Hawaii County and Kume Island is the celebration of the Sister City Agreement signed three years ago. At the end of the conference, Kume Island Town hosted a reception for delegates and local townspeople to celebrate the development of close relations including a yearly educational exchange between high school students. Local group performed with foods highlighting the numerous delicacies created with deep seawater.

IMG_1965One of the driving forces behind the agreement and development of OTEC both in Hawaii and Japan was Guy Toyama, an activist that visited prior to the approval of the OTEC facility on Kumejima. Guy died suddenly during a marathon in 2012, and many people in Japan miss him. We were honored his wife Rika Toyama visited with the delegation from Hawaii and participated in both the workshop and reception. It meant a lot for many of the participants to be able to meet her and share their memories of Guy. We hope these workshops will continue to ensure Guy’s dream of large scale OTEC is realized and so that OTEC is developed with international understanding and support.

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The Foundation of GO SEA

IMG_9378July 21, 2014 was a Japanese National Holiday, namely Marine Day, a holiday to give thanks for the ocean’s bounty and consider the importance of such resources to the island nation¹. This year, a group of Japanese Universities, Businesses, and other interested parties joined together to form the “Global Ocean reSource and Energy Association” or GO SEA (note: the official English name is still tentative).

The founder of this group, Kume Island‘s Mayor Haruo Ota writes,

Until now, deep seawater use has been separate by industry. Remote island economies need a more comprehensive solution. The “Kume Island Model” is a progressive approach in combining energy, local food production, new industries, and efficient use of deep seawater resources in an environmentally friendly, self-sustaining, and economically beneficial way as a demonstration for domestic and international development.

For the past fourteen years the Okinawa Deep Seawater Research Institute has been researching Deep Sea Water Utilization. This past year, Okinawa prefecture also began operation of our 50kw OTEC demonstration facility. The combination of these two fields, along with plans for future integration is an essential part of the “Kume Island Model.”

With the selection of Kume Island as a Ocean Research Area earlier this month, Mayor Ota and  supporting parties saw a need to create a group capable of integrating the various interests in to an association that can promote and enable the effective and efficient use of this important natural resource.

Association Initialization

IMG_9370Inviting more than 50 groups, Kumejima Town hosted a meeting and seminar to discuss and formalize the creation of this new organization. Participants were presented with aspects of the charter, given time to ask questions, then members voted by acclamation. Since invitees were presented with the major key elements prior to arrival, many had a clear understanding of the association’s goals.

Key participants include representatives from Tokyo University, Saga University, Ryukyu University, the Okinawa Institute of Science and Technology Graduate School, Okinawa Prefecture, Kume Island Town, local industries, and several observers including Government representatives and the Naha Branch of the US Embassy. While the group has started domestically, the goal is to create a truly international group capable of moving Ocean Energy (such as OTEC) and Resource Utilization forward.


After the basic Charter was approved by all parties, Professor Emeritus of Tokyo University and President of the Deep Ocean Water Applications Society Masayuki Takahashi presented on the state of Deep Ocean Water Use in Japan, providing all members with a history of OTEC and Deep Sea Water use around the world.

IMG_9477Members who had yet to see OTEC and Kume Island’s Deep Seawater industries in action had the opportunity to tour our facilities Tuesday morning.

Going Forward

The initial goal of the Group is the creation of an Ocean Energy Research Institute on Kume Island. Funding and constructing the facilities will give researchers access to both the Deep Sea Water and OTEC technologies needed to pave the way towards realization of the Kume Island Model.

IMG_9484While this group has begun domestically in Japan, participants plan to extend invitations to other interested parties around the world. Creating an efficient and practical OTEC model that can be adjusted and studied for specific locations should provide all countries with positive economic and social benefits. Since OTEC and Deep Seawater Use require a significant capital investment for practical research, allowing multiple interests to study the effects of different projects in a set location should reduce the costs and risk of future systems. With it’s years of experience and existing industries ready to expand, Kume Island is uniquely poised for expanded practical research and applications.

OTEC Okinawa looks forward to working with the amazing researchers and business to make OTEC a reality around the world.





久米島町では、平成23年3月に総務省の「緑の分権改革推進事業」を活用した「久米島海洋深層水複合利用基本調査 調査報告書(ダウンロード可)」をまとめており、その中で海洋深層水が久米島において年間20億円の産業になっていることが報告され、さらに深層水を水産、農業、冷房、発電など複合的に利用し、エネルギー自給と産業の自立型コミュニティのモデルとする「久米島モデル」を提案しています。







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Kume Island Selected for Ocean Research Area

IMG_8754On July 7, NHK reported that a decision had been reached for the locations of Ocean Energy Research areas in Japanese waters. Eleven sites were proposed by seven of Japan’s prefectures. After consideration of all the sites, six were chosen for this comprehensive maritime policy. The sites chosen were in the waters of Niigata, Saga, Nagasaki, and Okinawa, with three sites near Nagasaki.

The sites will be opened to universities and corporations for development and research of ocean energies including wind, tide, wave and Ocean Thermal Energy Conversion. A similar system has been in place in the UK for the past 10 years, fostering development of ocean energies.

At OTEC Okinawa we look forward to learning more about this important step in developing ocean energy in Japan. Kume Island’s selection as a location highlights the importance of OTEC in Japan’s national ocean energy policies and should pave the way for more efficient project development.






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Typhoon 1408 and Coralway

With the end of spring Typhoon season has started in Japan. During the next few months, the warm temperatures and white sand beaches will bring many visitors to Okinawa. It’s also one of the best times to visit the OTEC facility since the chances of sunny skies are so good.

Unfortunately, during this time typhoons will occasionally sweep through the region. Most of the time there is several days warning so that you can easily change travel plans if you need to. This week, from around Tuesday morning through Wednesday Tyhpoon 1408, an unusually strong category 5 typhoon is projected to pass directly over Kume Island. While the course of the typhoon may change, we expect to close the facility to visitors if the area of intense winds (more than 50kt) passes over our facility.

Though our facility will be closed to the public in inclement weather, the facility itself has been engineered to withstand the high winds and rain that may happen during typhoons. The ocean pipelines bringing water into the facility have operated for 14 years with no issues, even during typhoons since they are partially underground and bring water from 15 meters or more below the surface.

Please keep an eye on weather websites such as or for updates.

Coralway Magazine

Separately, if you happen to be flying among the Okinawa Islands between July and August, check out JAL’s in-flight magazine Coralway for an article on the OTEC facility and Deep Sea Water use on Kume Island!

The article is in Japanese (as is most of the magazine), however there are some great photos highlighting the amazing products in Okinawa!












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海洋温度差発電実証設備 来場者数2,000人を達成しました!


140626逗子開成高校① 圧縮 140626逗子開成高校② 圧縮





見学はお問合せから予約できます。無料でガイド付き(海洋深層水、研究所、OTECの概要説明と設備のご案内)。所要時間は30分~1時間程度。見学受付は平日の9:00~17:00(休日の場合は要相談)。個人でも団体でも可。連絡はこちら(098-896-8655:沖縄県海洋深層水研究所内 ヒビノ)まで。

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