Editing Ocean thermal energy conversion (section)

== History ==
[[File:Georges Claude à l'Institut 1926.jpg|thumb|French engineer [[Georges Claude]] conducting a demonstration on ocean thermal energy conversion at the Institut de France in 1926]]
Attempts to develop and refine OTEC technology started in the 1880s. In 1881, [[Jacques Arsene d'Arsonval]], a French [[physicist]], proposed tapping the thermal energy of the ocean. D'Arsonval's student, [[Georges Claude]], built the first OTEC plant, in Matanzas, Cuba in 1930.<ref>{{Cite journal
  | last = Chiles
  | first = Jamesin 
  | title = The Other Renewable Energy
  | journal = Invention and Technology
  | volume = 23
  | issue = 4
  | pages = 24–35
  | date = Winter 2009
  }}
</ref><ref>[https://books.google.com/books?id=qOIDAAAAMBAJ&dq=Popular+Science+1930+plane+%22Popular+Mechanics%22&pg=PA881 "Power from the Sea" ''Popular Mechanics'', December 1930, pp 881-882] detail article and photos of Cuban power plant</ref> The system generated 22&nbsp;[[Kilowatt|kW]] of [[electricity]] with a low-[[pressure]] [[turbine]].<ref name="dow-book">{{Cite book|last=Takahashi|first=Masayuki Mac|url=http://www.terrapub.co.jp/e-library/dow/index.html|title=Deep Ocean Water as Our Next Natural Resource|publisher=Terra Scientific Publishing Company|year=2000|isbn=978-4-88704-125-7|location=Tokyo, Japan|translator-last=Kitazawa|translator-first=Kazuhiro|orig-year=1991|translator-last2=Snowden|translator-first2=Paul}}</ref> The plant was later destroyed in a storm.<ref name="Avery, William H 1994">Avery, William H. and Chih Wu. Renewable Energy From the Ocean: A Guide to OTEC.	New York: Oxford University Press. 1994.{{pn|date=October 2022}}</ref>

In 1935, Claude constructed a plant aboard a 10,000-[[ton]] cargo vessel moored off the coast of Brazil. Weather and waves destroyed it before it could generate net power.<ref name=dow-book/> (Net power is the amount of power generated after subtracting power needed to run the system).

In 1956, French scientists designed a 3&nbsp;[[Megawatt|MW]] plant for [[Abidjan]], Ivory Coast. The plant was never completed, because new finds of large amounts of cheap petroleum made it uneconomical.<ref name=dow-book/>

In 1962, J. Hilbert Anderson and James H. Anderson, Jr. focused on increasing component efficiency. They patented their new "closed cycle" design in 1967.<ref name=closed-cycle-patent>{{Ref patent | country = US | number = 3312054 | status = patent | title = Sea Water Power Plant | gdate = 1967-04-04 | fdate = 1966-09-27 | invent1 = J.H. Anderson}}</ref> This design improved upon the original closed-cycle Rankine system, and included this in an outline for a plant that would produce power at lower cost than oil or coal. At the time, however, their research garnered little attention since coal and nuclear were considered the future of energy.<ref name="Avery, William H 1994"/>

Japan is a major contributor to the development of OTEC technology.<ref name=osti-assessment>{{Cite report |title= An Assessment of Research and Development Leadership in Ocean Energy Technologies |date=April 1994| last= Bruch |first= Vicki L. |location= Albuquerque, NM |publisher= Sandia National Laboratories: Energy Policy and Planning Department |id= SAND93-3946 |url= https://www.osti.gov/servlets/purl/10154003 |doi= 10.2172/10154003}}</ref> Beginning in 1970 the [[Tokyo Electric Power Company]] successfully built and deployed a 100&nbsp;kW closed-cycle OTEC plant on the island of [[Nauru]].<ref name=osti-assessment/>  The plant became operational on 14 October 1981, producing about 120&nbsp;kW of electricity; 90&nbsp;kW was used to power the plant and the remaining electricity was used to power a school and other places.<ref name=dow-book/> This set a world record for power output from an OTEC system where the power was sent to a real (as opposed to an experimental) power grid.<ref name=nauru-outline>{{Cite journal | title =  Outline of the 100 kW OTEC Pilot Plant in the Republic of Nauru | vauthors = Mitsui T, Ito F, Seya Y, Nakamoto Y |date=September 1983 | journal = IEEE Transactions on Power Apparatus and Systems | volume = PAS-102 | issue = 9 | pages = 3167–3171 |url = http://library.greenocean.org/oteclibrary/otecdesigns/OTEC-nauru.pdf/view | doi = 10.1109/TPAS.1983.318124 |bibcode =1983ITPAS.102.3167M | s2cid = 8924555 |archive-url=https://web.archive.org/web/20080502133042/http://library.greenocean.org/oteclibrary/otecdesigns/OTEC-nauru.pdf/view |archive-date=2008-05-02 |url-status=dead}}</ref>

1981 also saw a major development in OTEC technology when Russian engineer, Dr. Alexander Kalina, used a mixture of ammonia and water to produce electricity. This new ammonia-water mixture greatly improved the efficiency of the power cycle. In 1994, the Institute of Ocean Energy at [[Saga University]] designed and constructed a 4.5&nbsp;kW plant for the purpose of testing a newly invented Uehara cycle, also named after its inventor Haruo Uehara. This cycle included absorption and extraction processes that allow this system to outperform the Kalina cycle by 1–2%.<ref>Finney, Karen Anne. "Ocean Thermal Energy Conversion". Guelph Engineering Journal. 2008.</ref>

The 1970s saw an uptick in OTEC research and development during the post 1973 Arab-Israeli War, which caused oil prices to triple. The U.S. federal government poured $260 million into OTEC research after President Carter signed a law that committed the US to a production goal of 10,000&nbsp;MW of electricity from OTEC systems by 1999.<ref>{{cite news|last=Daly|first=John|title=Hawaii About to Crack Ocean Thermal Energy Conversion Roadblocks?|url=http://oilprice.com/Alternative-Energy/Renewable-Energy/Hawaii-About-To-Crack-Ocean-Thermal-Energy-Conversion-Roadblocks.html|access-date=28 March 2013|newspaper=OilPrice.com|date=December 5, 2011}}</ref>

[[File:OTEC in Hawaii.jpg|thumb|View of a land based OTEC facility at [[Keahole Point]] on the [[Kona District, Hawaii|Kona]] coast of [[Hawaii]]]]

In 1974, The U.S. established the [[Natural Energy Laboratory of Hawaii Authority]] (NELHA) at [[Keahole Point]] on the [[Kona District, Hawaii|Kona coast]] of [[Hawaii (island)|Hawaii]]. Hawaii is the best US OTEC location, due to its warm surface water, access to very deep, very cold water, and high electricity costs. The laboratory has become a leading test facility for OTEC technology.<ref name=elec-costs>{{cite web | title =  Average Retail Price of Electricity to Ultimate Customers by End-Use Sector, by State | publisher = [[Energy Information Administration]] |date = September 2007| url = http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html}}</ref> In the same year, Lockheed received a grant from the U.S. National Science Foundation to study OTEC. This eventually led to an effort by Lockheed, the US Navy, Makai Ocean Engineering, Dillingham Construction, and other firms to build the world's first and only net-power producing OTEC plant, dubbed "Mini-OTEC"<ref name="lockheed1">{{cite web|author1=L. Meyer|author2=D. Cooper|author3=R. Varley|title=Are We There Yet? A Developer's Roadmap to OTEC Commercialization|url=http://hinmrec.hnei.hawaii.edu/wp-content/uploads/2010/01/OTEC-Road-to-Commercialization-September-2011-_-LM.pdf|website=Hawaii National Marine Renewable Energy Center|access-date=28 March 2013|archive-date=24 October 2020|archive-url=https://web.archive.org/web/20201024125949/http://hinmrec.hnei.hawaii.edu/wp-content/uploads/2010/01/OTEC-Road-to-Commercialization-September-2011-_-LM.pdf|url-status=dead}}</ref> For three months in 1979, a small amount of electricity was generated. NELHA operated a 250&nbsp;kW demonstration plant for six years in the 1990s.<ref name="EIA">{{cite web |url=https://www.eia.gov/energyexplained/hydropower/ocean-thermal-energy-conversion.php |title=Hydropower explained: Ocean thermal energy conversion |publisher=[[Energy Information Administration]] |date=September 18, 2023}}</ref> With funding from the [[United States Navy]], a 105&nbsp;kW plant at the site began supplying energy to the local power grid in 2015.<ref name="EIA" />

A European initiative EUROCEAN - a privately funded joint venture of 9 European companies already active in offshore engineering - was active in promoting OTEC from 1979 to 1983. Initially a large scale offshore facility was studied. Later a 100&nbsp;kW land based installation was studied combining land based OTEC with Desalination and Aquaculture nicknamed ODA. This was based on the results from a small scale aquaculture facility at the island of St Croix that used a deepwater supply line to feed the aquaculture basins. Also a shore based open cycle plant was investigated.
The location of the case of study was the Dutch Kingdom related island [[Curaçao]].<ref>{{Cite journal |last=Lachmann |first=B. A. P. L. |date=1979-01-01 |title=Eurocean OTEC project |journal=Ocean Thermal Energy for the 80's |url=https://ui.adsabs.harvard.edu/abs/1979oteo....1....2L |volume=1 |pages=2A–1/1|bibcode=1979oteo....1....2L }}</ref>

Research related to making open-cycle OTEC a reality began earnestly in 1979 at the Solar Energy Research Institute (SERI) with funding from the US Department of Energy. Evaporators and suitably configured direct-contact condensers were developed and patented by SERI (see<ref>{{cite journal |last1=Bharathan |first1=D. |last2=Penney |first2=T. |title=Flash Evaporation From Turbulent Water Jets |journal=Journal of Heat Transfer |date=1 May 1984 |volume=106 |issue=2 |pages=407–416 |doi=10.1115/1.3246687 }}</ref><ref>Bharathan, D. (1984). Method and Apparatus for Flash Evaporation of Liquids. U.S. Patent No. 4,474,142.</ref><ref>Bharathan, D.; Parsons, B. K.; Althof, J. A. (1988). Direct-Contact Condensers for Open-Cycle OTEC Applications: Model Validation with Fresh Water Experiments for Structured Packings. 272 pp.; NREL Report No. TR-253-3108.</ref>). An original design for a power-producing experiment, then called the 165-kW experiment was described by [[Frank Kreith|Kreith]] and Bharathan<ref>{{cite journal |last1=Bharathan |first1=D. |last2=Kreith |first2=F. |last3=Schlepp |first3=D. |last4=Owens |first4=W. L. |title=Heat and Mass Transfer in Open-Cycle OTEC Systems |journal=Heat Transfer Engineering |date=January 1984 |volume=5 |issue=1–2 |pages=17–30 |doi=10.1080/01457638408962766 |bibcode=1984HTrEn...5...17B }}</ref> and<ref>{{cite journal |last1=Kreith |first1=F. |last2=Bharathan |first2=D. |title=1986 Max Jakob Memorial Award Lecture: Heat Transfer Research for Ocean Thermal Energy Conversion |journal=Journal of Heat Transfer |date=1 February 1988 |volume=110 |issue=1 |pages=5–22 |doi=10.1115/1.3250473 }}</ref> as the [[Max Jakob Memorial Award]] Lecture. The initial design used two parallel axial turbines, using last stage rotors taken from large steam turbines. Later, a team led by Dr. Bharathan at the National Renewable Energy Laboratory (NREL) developed the initial conceptual design for up-dated 210&nbsp;kW open-cycle OTEC experiment (<ref>Bharathan, D.; Green, H. J.; Link, H. F.; Parsons, B. K.; Parsons, J. M.; Zangrando, F. (1990). Conceptual Design of an Open-Cycle Ocean Thermal Energy Conversion Net Power-Producing Experiment (OC-OTEC NPPE). 160 pp.; NREL Report No. TR-253-3616.</ref>). This design integrated all components of the cycle, namely, the evaporator, condenser and the turbine into one single vacuum vessel, with the turbine mounted on top to prevent any potential for water to reach it. The vessel was made of concrete as the first process vacuum vessel of its kind. Attempts to make all components using low-cost plastic material could not be fully achieved, as some conservatism was required for the turbine and the vacuum pumps developed as the first of their kind. Later Dr. Bharathan worked with a team of engineers at the Pacific Institute for High Technology Research (PICHTR) to further pursue this design through preliminary and final stages. It was renamed the Net Power Producing Experiment (NPPE) and was constructed at the Natural Energy Laboratory of Hawaii (NELH) by PICHTR by a team led by Chief Engineer Don Evans and the project was managed by Dr. Luis Vega.

[[File:otec2.jpg|thumb|India – pipes used for OTEC (left) and floating OTEC plant constructed in 2000 (right)]]

In 2002, India tested a 1&nbsp;MW floating OTEC pilot plant near Tamil Nadu. The plant was ultimately unsuccessful due to a failure of the deep sea cold water pipe.<ref>Avery, William H. and Chih Wu. Renewable Energy From the Ocean: A Guide to OTEC. New York: Oxford University Press. 1994.{{pn|date=October 2022}}</ref> [[Government of India|Its government]] continues to sponsor research.<ref>{{cite web | url = http://www.makai.com/ocean-thermal-energy-conversion/ | title = Deep Pipelines for Ocean Thermal Energy Conversion | access-date = 8 January 2020 | archive-date = 17 February 2022 | archive-url = https://web.archive.org/web/20220217122357/http://www.makai.com/ocean-thermal-energy-conversion/ | url-status = dead }}</ref>

In 2006, Makai Ocean Engineering was awarded a contract from the U.S. [[Office of Naval Research]] (ONR) to investigate the potential for OTEC to produce nationally significant quantities of hydrogen in at-sea floating plants located in warm, tropical waters. Realizing the need for larger partners to actually commercialize OTEC, Makai approached Lockheed Martin to renew their previous relationship and determine if the time was ready for OTEC. And so in 2007, Lockheed Martin resumed work in OTEC and became a subcontractor to Makai to support their SBIR, which was followed by other subsequent collaborations<ref name="lockheed1" />

In March 2011, Ocean Thermal Energy Corporation signed an Energy Services Agreement (ESA) with the Baha Mar resort, Nassau, Bahamas, for the world's first and largest seawater air conditioning (SWAC) system.<ref>{{cite web|url=http://otecorporation.com/2011/12/19/baha-mar-resort-signs-energy-services-agreement-with-ote-corporation/|title=Baha Mar Resort Signs Energy Services Agreement with OTE Corporation|last=Spaine|date=19 December 2011|access-date=26 February 2017|archive-date=12 February 2019|archive-url=https://web.archive.org/web/20190212011453/http://otecorporation.com/2011/12/19/baha-mar-resort-signs-energy-services-agreement-with-ote-corporation/|url-status=dead}}</ref> In June 2015, the project was put on pause while the resort resolved financial and ownership issues.<ref>{{cite web|url=https://www.forbes.com/sites/erincarlyle/2015/06/29/baha-mar-resorts-to-chapter-11-bankruptcy-blames-china-construction-for-delays/|title=Baha Mar Resorts To Chapter 11 Bankruptcy, Blames China Construction For Delays|first=Erin|last=Carlyle|website=Forbes}}</ref> In August 2016, it was announced that the issues had been resolved and that the resort would open in March 2017.<ref name="otecorporation.com">{{Cite web |url=http://otecorporation.com/2016/08/30/ocean-thermal-energy-corporation-reports-announcement-bahamian-government-remobilization-completion-opening-baha-mar-beach-resort/ |title=Ocean Thermal Energy Corporation Reports Announcement by Bahamian Government of the Remobilization, Completion, and Opening of the Baha Mar Beach Resort - OTE Corporation |access-date=2016-10-13 |archive-date=2016-10-14 |archive-url=https://web.archive.org/web/20161014073737/http://otecorporation.com/2016/08/30/ocean-thermal-energy-corporation-reports-announcement-bahamian-government-remobilization-completion-opening-baha-mar-beach-resort/ |url-status=dead }}</ref> It is expected that the SWAC system's construction will resume at that time.

In July 2011, Makai Ocean Engineering completed the design and construction of an OTEC Heat Exchanger Test Facility at the [[Natural Energy Laboratory of Hawaii]]. The purpose of the facility is to arrive at an optimal design for OTEC heat exchangers, increasing performance and useful life while reducing cost (heat exchangers being the #1 cost driver for an OTEC plant).<ref>{{cite web|title=Makai Ocean Engineering's Heat Exchanger Test Facility opened|url=http://www.otecnews.org/2011/11/makai-ocean-engineerings-heat-exchanger-test-facility-opened/|website=www.otecnews.org|access-date=28 March 2013|date=2011-11-22}}</ref> And in March 2013, Makai announced an award to install and operate a 100 kilowatt turbine on the OTEC Heat Exchanger Test Facility, and once again connect OTEC power to the grid.<ref>{{cite web|title=Makai Ocean Engineering working with Navy on Big Island OTEC project|url=http://www.bizjournals.com/pacific/news/2013/03/19/makai-ocean-engineering-working-with.html|access-date=28 March 2013}}</ref><ref>{{cite web |title=Makai Ocean Engineering to add 100kW turbine generator to Kona, Hawaii OTEC test facility |url=http://www.districtenergy.org/blog/2013/03/19/makai-ocean-engineering-to-add-100kw-turbine-generator-to-kona-hawaii-otec-test-facility/ |website=International District Energy Association |access-date=2013-03-28 |archive-url=https://web.archive.org/web/20141110122515/http://www.districtenergy.org/blog/2013/03/19/makai-ocean-engineering-to-add-100kw-turbine-generator-to-kona-hawaii-otec-test-facility/ |archive-date=2014-11-10 |url-status=dead }}</ref>

In July 2016, the Virgin Islands Public Services Commission approved Ocean Thermal Energy Corporation's application to become a Qualified Facility. The company is thus permitted to begin negotiations with the Virgin Islands Water and Power Authority (WAPA) for a Power Purchase Agreement (PPA) pertaining to an Ocean Thermal Energy Conversion (OTEC) plant on the island of St. Croix. This would be the world's first commercial OTEC plant.<ref name="ReferenceA">{{Cite web|url = http://otecorporation.com/2016/07/18/ote-receives-approval-otec-system-usvi/|title = OTE Receives Approval for OTEC System in the USVI|date = 18 July 2016|access-date = 26 February 2017|archive-date = 12 February 2019|archive-url = https://web.archive.org/web/20190212011537/http://otecorporation.com/2016/07/18/ote-receives-approval-otec-system-usvi/|url-status = dead}}</ref><ref name="lancasteronline.com">{{cite web|url=https://lancasteronline.com/business/local_business/ocean-thermal-to-begin-talks-for-renewable-energy-plants-in/article_e68b41f4-4da4-11e6-8d72-1352558baa6f.html|title=Ocean Thermal to begin talks for renewable energy plants in St. Croix, St. Thomas |first=Tim |last=Mekeel |website=LancasterOnline|date=19 July 2016 }}</ref>

A project is set to be installed in the African country of São Tomé and Príncipe, which will be the first commercial-scale floating OTEC platform in the world.<ref>{{Cite web|url=https://www.newscientist.com/article/2401171-ocean-heat-could-supply-essentially-endless-clean-energy-to-islands/|title=Ocean heat could supply essentially endless clean energy to islands|website=New Scientist}}</ref> Developed by Global OTEC, the structure named Dominique will generate 1.5MW, with subsequent barges being installed to help supply the full demand of the country.<ref>{{Cite web|url=https://newatlas.com/energy/global-otec-power-dominique/|title=First commercial-scale ocean thermal energy generator slated for 2025|date=14 November 2023|website=New Atlas}}</ref> In 2022, an MoU was signed between the government and British startup [https://globalotec.co/ Global OTEC].<ref>{{Cite web|url=https://www.aler-renovaveis.org/en/communication/news/sao-tome-and-principe-and-global-otec-sign-agreement-to-develop-the-first-power-purchase-agreement-for-otec-in-sids/|title=ALER - Lusophone Renewable Energy Association - Communication - News - São Tomé and Príncipe signed an agreement to develop the first ocean energy project in the SIDS|website=www.aler-renovaveis.org}}</ref>