Jump to content

Floating wind turbine: Difference between revisions

From Wikipedia, the free encyclopedia
Content deleted Content added
AnomieBOT (talk | contribs)
m Dating maintenance tags: {{Better source}}
rewording and better English
Line 1: Line 1:
{{Expand German|Schwimmende Windkraftanlage|date=January 2012}}
{{Expand German|Schwimmende Windkraftanlage|date=January 2012}}
[[File:Hywind.jpg|thumb|375px|right|The world’s first full-scale floating wind turbine, Hywind, being assembled in the Åmøy Fjord near [[Stavanger]], [[Norway]], before deployment in the [[North Sea]].]]
[[File:Hywind.jpg|thumb|375px|right|The world’s first full-scale floating wind turbine, Hywind, being assembled in the Åmøy Fjord near [[Stavanger]], [[Norway]], before deployment in the [[North Sea]].]]
A '''floating wind turbine''' is an offshore [[wind turbine]] mounted on a floating structure that allows the turbine to generate [[electricity]] in water depths where bottom-mounted towers are not feasible.<ref name=ge20110913/> The [[wind]] can be stronger and steadier over water due to the absence of topographic features that may disrupt wind flow.<ref name="Musial2003"/>
A '''floating wind turbine''' is an offshore [[wind turbine]] mounted on a floating structure that allows the turbine to generate [[electricity]] in water depths where bottom-mounted towers are not feasible.<ref name=ge20110913/>
Locating wind farms out at sea can reduce [[visual pollution]]<ref name=ge20110913>
{{cite news |last=Laskow|first=Sarah |title=Hope Floats for a New Generation of Deep-Water Wind Farms |url=http://www.good.is/post/hope-floats-for-a-new-generation-of-deep-water-wind-farms/ |accessdate=2011-10-12 |newspaper=Good Environment |date=2011-09-13 }}</ref> whilst providing better accommodation for fishing and shipping lanes.<ref>{{cite web
The relocation of wind farms into the sea can reduce [[visual pollution]]<ref name=ge20110913>
{{cite news |last=Laskow|first=Sarah |title=Hope Floats for a New Generation of Deep-Water Wind Farms |url=http://www.good.is/post/hope-floats-for-a-new-generation-of-deep-water-wind-farms/ |accessdate=2011-10-12 |newspaper=Good Environment |date=2011-09-13 }}</ref> if the windmills are sited more than {{convert|12|mi}} offshore, provide better accommodation of fishing and shipping lanes, and allow silting near heavily developed coastal cities.<ref>{{cite web
|url=http://www.dailyfinance.com/2009/09/09/the-worlds-first-floating-wind-turbine-goes-on-line-in-norway/
|url=http://www.dailyfinance.com/2009/09/09/the-worlds-first-floating-wind-turbine-goes-on-line-in-norway/
|title=The world's first floating wind turbine goes on line in Norway
|title=The world's first floating wind turbine goes on line in Norway
Line 18: Line 18:
|quote=<!-- This citation added to support the removal of unsupported statements regarding competition between wind turbines and agriculture -->
|quote=<!-- This citation added to support the removal of unsupported statements regarding competition between wind turbines and agriculture -->
}}</ref>
}}</ref>
In addition, the [[wind]] is typically more consistent and stronger over the sea, due to the absence of topographic features that disrupt wind flow.<ref name="Musial2003"/>


Floating wind parks are [[wind farms]] that site several floating wind turbines closely together to take advantage of common infrastructure such as power transmission facilities.{{Citation needed|date=October 2011}}
Floating wind parks are [[wind farms]] that site several floating wind turbines closely together to take advantage of common infrastructure such as power transmission facilities.{{Citation needed|date=October 2011}}

Revision as of 21:45, 29 March 2012

The world’s first full-scale floating wind turbine, Hywind, being assembled in the Åmøy Fjord near Stavanger, Norway, before deployment in the North Sea.

A floating wind turbine is an offshore wind turbine mounted on a floating structure that allows the turbine to generate electricity in water depths where bottom-mounted towers are not feasible.[1] Locating wind farms out at sea can reduce visual pollution[1] whilst providing better accommodation for fishing and shipping lanes.[2][3] In addition, the wind is typically more consistent and stronger over the sea, due to the absence of topographic features that disrupt wind flow.[4]

Floating wind parks are wind farms that site several floating wind turbines closely together to take advantage of common infrastructure such as power transmission facilities.[citation needed]

History

The concept for "large-scale offshore floating wind turbines was introduced by Professor William E. Heronemus at the University of Massachusetts in 1972. [I]t was not until the mid 1990s, after the commercial wind industry was well established, that the topic was taken up again by the mainstream research community."[4] As of 2003, existing offshore fixed-bottom wind turbine technology deployments had been limited to water depths of 30 metres. Worldwide deep-water wind resources are extremely abundant in subsea areas with depths up to 600 metres, which are thought to best facilitate transmission of the generated electric power to shore communities.[4]

Operational deep-water platforms

A tension leg mooring system as used by Blue H: left-hand tower-bearing structure (grey) is free floating, the right-hand structure is pulled by the tensioned cables (red) down towards the seabed anchors (light-grey)

In 2011 three floating wind turbine support structures were installed.[5]

Blue H deployed the first 80 kW floating wind turbine 113 kilometres (70 mi) off the coast of Italy in December, 2007. It was then decommissioned at the end of 2008 after completing a planned test year of gathering operational data. The wind turbine was not grid connected nor operational during the trials.[citation needed]

The first large-capacity, 2.3 megawatt floating wind turbine is Hywind, which became operational in the North Sea off of Norway in September 2009,[6] and is still operational as of October 2010.[7]

In October 2011, Principle Power's WindFloat Prototype was installed 4km offshore of Aguçadoura, Portugal in approximatly 45m of water (previously the Aguçadoura Wave Farm site). The WindFloat was fitted with a Vestas V80 2.0MW offshore wind turbine and grid connected. The installation was the first offshore wind turbine to be deployed without the use of any offshore heavy lift vessels as the turbine was fully commissioned onshore prior to the unit being towed offshore. Additionally this is the first offshore wind turbine installed in open Atlantic waters and make use of a semi-submersible type floating foundation.[8][better source needed]

SeaTwirl deployed their first floating grid connected wind turbine off the coast of Sweden in August, 2011. It was tested and de-commissioned.[5] This design intends to store energy in a flywheel. Thus, energy could be produced even after the wind has stopped blowing.[9][citation needed]

Blue H Technologies

Blue H Technologies of the Netherlands operated the first floating wind turbine,[7] a prototype deep-water platform with an 80-kilowatt turbine off Puglia, southeast Italy in 2008.[10] Installed 21 km off the coast in waters 113 metres deep in order to gather test data on wind and sea conditions, the small prototype unit was decommissioned at the end of 2008.[citation needed] Blue H has plans to build a 38-unit deepwater wind farm at the same location.[citation needed]

The Blue H technology utilized a tension-leg platform design and a two-bladed turbine.[citation needed] The two-bladed design can have a "much larger chord, which allows a higher tip speed than those of three-bladers. The resulting increased background noise of the two-blade rotor is not a limiting factor for offshore sites."[citation needed]

As of 2009, Blue H was building a full-scale commercial 2.4 MWe unit in Brindisi, Italy which it expected to deploy at the same site of the prototype in the southern Adriatic Sea in 2010.[needs update] This is the first unit in the planned 90 MW Tricase offshore wind farm, located more than 20 km off the Puglia coast line.

Hywind

A single floating cylindrical spar buoy moored by catenary cables. Hywind uses a ballasted catenary layout that adds 60 tonne weights hanging from the midpoint of each anchor cable to provide additional tension.

The world's first operational deep-water floating large-capacity wind turbine is the Hywind, in the North Sea off Norway.[6][11] The Hywind was towed out to sea in early June 2009.[12] The 2.3 megawatt turbine was constructed by Siemens Wind Power and mounted on a floating tower with a 100 metre deep draft. The float tower was constructed by Technip. Statoil says that floating wind turbines are still immature and commercialization is distant.[13][14]

The installation is owned by Statoil and will be tested for two years.[10] After assembly in the calmer waters of Åmøy Fjord near Stavanger, Norway, the 120-meter-tall tower with a 2.3 MW turbine was towed 10 km offshore into 220-metre-deep water, 10 km southwest of Karmøy, on 6 June 2009 for a two year test deployment."[10] Alexandra Beck Gjorv of Statoil said, "[The experiment] should help move offshore wind farms out of sight ... The global market for such turbines is potentially enormous, depending on how low we can press costs."[15] The unit became operational in the summer of 2009.[6] Hywind was inaugurated on 8 September 2009.[16][17] As of October 2010, after a full year of operation, the Hywind turbine is still operating and generating electricity for the Norwegian grid,[7] and still is as of February 2011.[18]

The turbine cost 400 million kroner (around US$62 million) to build and deploy.[19][20] The 13-kilometre (8.1 mi) long submarine power transmission cable was installed in July, 2009 and system test including rotor blades and initial power transmission was conducted shortly thereafter.[21] The installation is expected to generate about 9 GW·h of electricity annually.[22] The SWATH (Small Waterplane Area Twin Hull), a new class of offshore wind turbine service boat, will be tested at Hywind.[23]

Hywind delivered 7.3 GWh in 2010, and survived 11 meter waves with seemingly no wear.[24] As of June 2011, additional pilot Hywind installations are planned in the US and in the North Sea off the coast of Scotland.[25]

WindFloat by Principle Power

External videos
video icon A video describing the WindFloat.

WindFloat is a floating foundation for offshore wind turbines designed and patented by Principle Power. It is to be tested in autumn 2011 off the coast of Portugal with a Vestas V80 2MW wind turbine.[18]

The foundation attempts to improve dynamic stability at shallow draft[26] by dampening wave and turbine induced motion[27] utilizing a tri-column triangular platform with the wind turbine positioned on only one of the three columns. The triangular platform is then "moored with 4 lines, 2 of which are connected to the column stabilizing the turbine, thus creating an asymmetric" mooring to increase stability and reduce motion.[28]

As the wind shifts direction and changes the loads on the turbine and foundation, pumps will shift ballast water between foundation chambers.[29]

The project is managed by the joint venture WindPlus (led by electricity provider Energias de Portugal).[26]

Vestas turbines will be the standard for the project.[26]

Construction cost is expected to be below $30 million,[7] and funded by the project partners and Fundo de Apoio à Inovação.[30]

This technology could allow wind turbines to be sited in offshore areas that were previously considered inaccessible, areas having water depth exceeding 50 metres and more powerful wind resources than shallow-water offshore wind farms typically encounter.[31]

Topologies

Platform topologies can be classified into:[citation needed]

  • single-turbine-floater (one wind turbine mounted on a floating structure)[citation needed]
  • multiple turbine floaters (multiple wind turbines mounted on a floating structure)[citation needed]

Engineering considerations

Undersea mooring of floating wind turbines are accomplished with three principal mooring systems.[citation needed] Two common types of engineered design for anchoring floating structures include tension-leg and catenary loose mooring systems.[citation needed] Tension leg mooring systems have vertical tethers under tension providing large restoring moments in pitch and roll. Catenary mooring systems provide station keeping for an offshore structure yet provide little stiffness at low tensions."[32] A third form of mooring system is the ballasted catenary configuration, created by adding multiple-tonne weights hanging from the midsection of each anchor cable in order to provide additional cable tension and therefore increase stiffness of the above-water floating structure.[32]

Economics

"Technically, the [theoretical] feasibility of deepwater [floating] wind turbines is not questioned as long-term survivability of floating structures has already been successfully demonstrated by the marine and offshore oil industries over many decades. However, the economics that allowed the deployment of thousands of offshore oil rigs have yet to be demonstrated for floating wind turbine platforms. For deepwater wind turbines, a floating structure will replace pile-driven monopoles or conventional concrete bases that are commonly used as foundations for shallow water and land-based turbines. The floating structure must provide enough buoyancy to support the weight of the turbine and to restrain pitch, roll and heave motions within acceptable limits. The capital costs for the wind turbine itself will not be significantly higher than current marinized turbine costs in shallow water. Therefore, the economics of deepwater wind turbines will be determined primarily by the additional costs of the floating structure and power distribution system, which are offset by higher offshore winds and close proximity to large load centres (e.g. shorter transmission runs)."[4]

As of 2009 however, the economic feasibility of shallow-water offshore wind technologies is more completely understood. With empirical data obtained from fixed-bottom installations off many countries for over a decade now, representative costs are well understood. Shallow-water turbines cost between 2.4 and 3 million United States dollars per megawatt to install, according to the World Energy Council.[10]

As of 2009, the practical feasibility and per-unit economics of deep-water, floating-turbine offshore wind is yet to be seen. Initial deployment of single full-capacity turbines in deep-water locations began only in 2009.[10]

As of October 2010, new feasibility studies are supporting that floating turbines are becoming both technically and economically viable in the UK and global energy markets. "The higher up-front costs associated with developing floating wind turbines would be offset by the fact that they would be able to access areas of deep water off the coastlne of the UK where winds are stronger and reliable." [33]

The recent Offshore Valuation study conducted in the UK has confirmed that using just one third of the UK's wind, wave and tidal resource could generate energy equivalent to 1 billion barrels of oil per year; the same as North Sea oil and gas production. Some of the primary challenges are the coordination needed to develop transmission lines.[34]

Floating design concepts

External videos
video icon A video describing Ideol mobility concept

Ideol

Ideol is a French company that has patented a new floating platform concept specifically designed for offshore wind.

While the floater concept and patents are not yet publicly disclosed, the company is communicating on its web site[35] mobility solution to reduce wake losses in an offshore wind farm by repositioning the floating turbines depending on the wind direction. The company has patented a mechanical solution to move the floater along its mooring lines and has developed a software to optimize in real-time the farm layout. Eliminating wake losses allows to increase significantly the power production as well as to reduce the long-term components failures.[35]

According to publicly released information[35], Ideol has a construction and installation cost of around 1M Euro per MW. As such, the company intends to offer an alternative to fixed foundations starting from 40 m water depth.

OffshoreWind.biz reported that the company will build a 5 MW floating prototype off the European coast in 2013.[36]

Nautica Windpower

File:NauticaWindpower1.jpg
Nautica Windpower's AFT design features a downwind two-bladed rotor with passive wind alignment to reduce costs

Nautica Windpower uses a patented technology aimed at reducing system weight, complexity and costs for deep water sites. Scale model tests in open water have been conducted and structural dynamics modeling is under development for a multi-megawatt design.[37] Nautica Windpower's Advanced Floating Turbine (AFT) uses a single mooring line and a downwind two-bladed rotor configuration that is deflection tolerant and aligns itself with the wind without an active yaw system. Two-bladed, downwind turbine designs that can accommodate flexibility in the blades will potentially prolong blade lifetime, diminish structural system loads and reduce offshore maintenance needs, yielding lower lifecycle costs. [38]

OC3-Hywind

The International Energy Agency (IEA), under the auspices of their Offshore Code Comparison Collaboration (OC3) initiative, has completed high-level design and simulation modeling of the OC-3 Hywind system, a 5-MW wind turbine installed on a floating spar buoy, moored with catenary mooring lines, in water depth of 320 metres. The spar buoy platform would extend 120 meters below the surface and the mass of such a system, including ballast would exceed 7.4 million kg. [39]

DeepWind

Risø and 11 international partners started a 4-year program called DeepWind in October 2010 to create and test economical floating Vertical Axis Wind Turbines up to 20MW. The program is supported with 3m through EUs Seventh Framework Programme.[40][41] Partners include TUDelft, SINTEF, Statoil and United States National Renewable Energy Laboratory.[42]

VertiWind

VertiWind is a Vertical Axis Wind Turbine design created by Nenuphar http://www.nenuphar-wind.com/[full citation needed] and currently being tested by Technip http://www.technip.com/.[full citation needed] See http://www.nenuphar-wind.com/press[better source needed]

Proposals

Floating wind farms

As of September 2011, Japan plans to build a pilot floating wind farm, with six 2-megawatt turbines, off the Fukushima coast of northeast Japan where the recent disaster has created a scarcity of electric power.[43] After the evaluation phase is complete in 2016, "Japan plans to build as many as 80 floating wind turbines off Fukushima by 2020."[43] The cost is expected to be in the range of 10-20 billion Yen over five years to build the first six floating wind turbines.[44] Some foreign companies also plan to bid on the 1 GW large floating wind farm that Japan hopes to build by 2020.[45] In March 2012, Japan’s Ministry of Economy, Trade and Industry approved a 12.5bn yen ($154m) project to float a 2MW Fuji in March 2013 and two 7MW Mitsubishi hydraulic "SeaAngel" later about 20-40 km offshore in 100-150 meters of water depth. The Japanese Wind Power Association claims a potential of 519GW of floating offshore wind capacity in Japan.[46]

As of November 2011, Statoil plans to build a multi-turbine project in Scottish waters utilizing the Hywind design.[45]

The US State of Maine solicited proposals in September 2010 to build the world's first floating, commercial wind farm. The RFP is seeking proposals for 25 MW of deep-water offshore wind capacity to supply power for 20-year long-term contract period via grid-connected floating wind turbines in the Gulf of Maine. Successful bidders must enter into long-term power supply contracts with either Central Maine Power Company (CMP), Bangor Hydro-Electric Company (BHE), or Maine Public Service Company (MPS). Proposals were due by May 2011.[47] [48][needs update]

Some vendors who could bid on the proposed project have expressed concerns about dealing with the United States regulatory environment. Since the proposed site is in Federal waters, developers would need a permit from the Minerals Management Service, "which took more than seven years to approve a yet-to-be-built, shallow-water wind project off Cape Cod," and is also the agency under fire in June 2010 for lax oversight of deepwater oil drilling in Federal waters. "Uncertainty over regulatory hurdles in the United States ... is 'the Achilles heel' for Maine's ambitions for deepwater wind."[48]

See also

References

  1. ^ a b Laskow, Sarah (13 September 2011). "Hope Floats for a New Generation of Deep-Water Wind Farms". Good Environment. Retrieved 12 October 2011.
  2. ^ Mark Svenvold (9 September 2009). "The world's first floating wind turbine goes on line in Norway". DailyFinance.com. Retrieved 20 October 2009. {{cite web}}: External link in |author= (help)
  3. ^ Union of Concerned Scientists (15 July 2003). "Farming the Wind: Wind Power and Agriculture". Retrieved 20 October 2009.
  4. ^ a b c d Musial, W. (2003-11). "Feasibility of Floating Platform Systems for Wind Turbines" (PDF). NREL preprint (NREL/CP-500-34874). NREL: 14. Retrieved 2009-09-10. {{cite journal}}: |issue= has extra text (help); Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ a b Justin Wilkes et al. The European offshore wind industry key 2011 trends and statistics p5 European Wind Energy Association, January 2012. Accessed: 26 March 2012.
  6. ^ a b c Madslien, Jorn (8 September 2009). "Floating challenge for offshore wind turbine". BBC News. Retrieved 14 September 2009. {{cite journal}}: Cite journal requires |journal= (help)
  7. ^ a b c d Deep water wind turbines, The Institution of Engineering and Technology, 2010-10-18, accessed 2011-11-06.[dead link]
  8. ^ "First WindFloat Successfully Deployed Offshore". 30 November 2011.
  9. ^ "Sea Twirl - A New Type of Off Shore Wind Turbine", Applied Physics, Chalmers University of Technology, 11 November 2010, retrieved 26 September 2011 Template:Sv icon
  10. ^ a b c d e Patel, Prachi (22 June 2009). "Floating Wind Turbines to Be Tested". IEEE Spectrum. Retrieved 25 June 2009. {{cite news}}: Cite has empty unknown parameter: |coauthors= (help)
  11. ^ Ramsey Cox (February/March 2010). "Water Power + Wind Power = Win!". Mother Earth News. Retrieved 2010-05-03. {{cite web}}: Check date values in: |date= (help)
  12. ^ Madslien, Jorn (5 June 2009). "Floating wind turbine launched". BBC News. Retrieved 14 September 2009.
  13. ^ Jensen, Mette Buck. Vestas goes for floating wind turbines (in Danish) Ing.dk, 14 September 2009. Retrieved: 11 November 2010.
  14. ^ StatoilHydro inaugurates floating wind turbine Statoil, 8 September 2009. Retrieved: 11 November 2010.
  15. ^ "First offshore wind turbine goes to sea". UPI. 6 June 2009. Retrieved 7 June 2009.
  16. ^ "Technip and StatoilHydro Announce Inauguration of World's First Full-Scale Floating Wind Turbine". OilVoice. 13 September 2009. Retrieved 19 September 2009.
  17. ^ "Hywind floating wind turbine". Statoil. 8 September 2009. Retrieved 29 September 2009.
  18. ^ a b Shahan, Zachary. 1st-of-its-kind floating wind turbine technology to be deployed by Vestas & WindPlus Clean Technica, 23 February 2011. Accessed: 23 February 2011.
  19. ^ "Statoil Draws On Offshore Oil Expertise To Develop World's First Floating Wind Turbine". NewTechnology magazine. 8 September 2009. Retrieved 21 October 2009. {{cite journal}}: Cite journal requires |journal= (help)
  20. ^ Turker, Tux (19 May 2009). "Maine task force to identify offshore wind energy sites". Energy Current. Retrieved 7 June 2009.[dead link]
  21. ^ Donovan, Matthew (11 August 2009). "Subsea cable installed at Hywind project". Energy Current. Retrieved 2 September 2009.[dead link]
  22. ^ Terje Riis-Johansen, Minister of Petroleum and Energy, Norway (9 October 2009). "Speech: Opening of Hywind – the world's first full-scale floating wind turbine". Norway Ministry of Petroleum and Energy. Retrieved 21 October 2009.{{cite web}}: CS1 maint: multiple names: authors list (link)
  23. ^ Stensvold, Tore. Delivery of first wind turbine boat (in Norwegian) Weekly Technicals, 10 November 2010. Retrieved: 16 November 2010.
  24. ^ Nilsen, Jannicke. Statoil wants Hywind in Japan Teknisk Ukeblad, 4 April 2011. Accessed: 4 April 2011.
  25. ^ Garrett, Paul (24 June 2011). "Scotland and US next pilot sites for Hywind floating project". Windpower Monthly. Retrieved 27 September 2011.
  26. ^ a b c Shankleman, Jessica. Vestas floats plan for WindPlus offshore demo Business Green, 18 February 2011. Accessed: 23 February 2011.
  27. ^ Vestas, WindPlus to deploy floating wind turbine structure Composites World, 21 February 2011. Accessed: 23 February 2011.
  28. ^ Balogh, Emily (18 December 2008). "Deepwater Offshore Wind Power Generation Using Oil and Gas Platform Technology". RenewableEnergyWorld.com. Retrieved 3 September 2009.
  29. ^ Rasmussen, Daniel. Vestas in experiment with floating wind turbine (in Danish). Source: Ing.dk, 21 February 2011. Accessed: 22 February 2011. "When the wind turns, the platform is kept level by pumping more water into one of the three cylinders"
  30. ^ Press Release Principle Power, 18 February 2011. Accessed: 23 February 2011.
  31. ^ "Principle Power & EDP to Develop Floating Offshore Wind". RenewableEnergyWorld.com. 20 February 2009. Retrieved 3 September 2009.
  32. ^ a b Floating Offshore Wind Turbines: Responses in a Seastate -- Pareto Optimal Designs and Economic Assessment, P. Sclavounos et al, October 2007.
  33. ^ Floating turbines promise to deliver reliable wind, says report, guardian.co.uk, 2010-10-11, accessed 2010-11-02. "The higher up-front costs associated with developing floating wind turbines would be offset by the fact that they would be able to access areas of deep water off the coastlne of the UK where winds are stronger and reliable. That is the conclusion of a major feasibility study..."
  34. ^ [1], The Offshore Valuation, 2010-11-08, accessed 2010-11-08.
  35. ^ a b c "Ideol web site". 15 June 2011. Retrieved 15 June 2011.
  36. ^ "Ideol announces new floating platform". OffshoreWind.biz. 12 April 2011.
  37. ^ Braciszeski, Kevin (23 January 2010). "Why Not Floating Windmills?". Ludington Daily News. Retrieved 8 February 2010.
  38. ^ "U.S. Offshore Wind Energy: A Path Forward" (PDF). Working Paper page 24. U.S. Offshore Wind Collaborative. 16 October 2009. Retrieved 7 November 2009.
  39. ^ Offshore Code Comparison Collaboration within IEA Wind Task 23: Phase IV Results Regarding Floating Wind Turbine Modeling, 2010 European Wind Energy Conference (EWEC), 20–23 April 2010, Warsaw, Poland, accessed 2010-09-11.
  40. ^ Stage, Mie (11 November 2010). "Risø floats 20MW" (in Danish). Ingeniøren. Retrieved 17 January 2011.
  41. ^ DeepWind Risø, sourcedate. Retrieved: 11 November 2010.
  42. ^ Munck, Susanne. Future turbines Risø, Danish, 8 November 2010. Retrieved: 11 November 2010.
  43. ^ a b "Japan Plans Floating Wind Power Plant". Breakbulk. 16 September 2011. Retrieved 12 October 2011.
  44. ^ Yoko Kubota Japan plans floating wind power for Fukushima coast Reuters, 13 September 2011. Accessed: 19 September 2011.
  45. ^ a b Quilter, James (1 November 2011). "Statoil looks to Japan with Hywind concept". WindPower Monthly. Retrieved 1 December 2011.
  46. ^ Patton, Dominique. Mitsubishi and Fuji named for Fukushima offshore wind farm Recharge News, 6 March 2012. Accessed: 8 March 2012.
  47. ^ Maine seeks 30MW of offshore wind and tidal pilots, BrighterEnergy.org, 20100903, accessed 2010-09-12.
  48. ^ a b State point man on offshore wind clearly energized, Maine Sunday Telegram, 2010-06-06, accessed 2010-06-13, "In September, the state plans to send out bids to build the world's first floating, commercial wind farm off the Maine coast."