Floating wind turbine
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. Locating wind farms out at sea can reduce visual pollution while providing better accommodation for fishing and shipping lanes. In addition, the wind is typically more consistent and stronger over the sea, due to the absence of topographic features that disrupt wind flow.
- 1 History
- 2 Topologies
- 3 Engineering considerations
- 4 Economics
- 5 Floating design concepts
- 6 Proposals
- 7 Research
- 8 Other applications
- 9 See also
- 10 References
- 11 Bibliography
- 12 External links
The concept for large-scale offshore floating wind turbines was introduced by Professor William E. Heronemus at the University of Massachusetts Amherst in 1972. It 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. 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. Two-thirds of the North Sea is between 50 and 220 meters deep.
In June 2013, the University of Maine made history with its VolturnUS 1:8, a 65-foot-tall floating turbine prototype that is 1:8th the scale of a 6-megawatt (MW), 450-foot rotor diameter design. VolturnUS 1:8 was the first grid-connected offshore wind turbine deployed in the Americas. The VolturnUS design utilizes a concrete semisubmersible floating hull and a composite materials tower designed to reduce both capital and Operation & Maintenance costs, and to allow local manufacturing throughout the US and the World. The VolturnUS technology is the culmination of collaborative research and development conducted by the University of Maine-led DeepCwind Consortium. U.S. Senators Susan Collins and Angus King announced in June 2016 that Maine’s New England Aqua Ventus I floating offshore wind demonstration project, designed by the DeepCwind Consortium, has been selected by the U.S. Department of Energy to participate in the Offshore Wind Advanced Technology Demonstration program.
New England Aqua Ventus I will now be one of up to three leading projects that are each eligible for up to $39.9 million in additional funding over three years for the construction phase of the demonstration program.
Operational deep-water platforms
In 2011 three floating wind turbine support structures were installed.
Blue H deployed the first 80-kW floating wind turbine 21.3 kilometres (13.2 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 first large-capacity, 2.3-megawatt floating wind turbine is Hywind, which became operational in the North Sea near Norway in September 2009, and is still operational as of October 2010[update].
In October 2011, Principle Power's WindFloat Prototype was installed 4 km offshore of Aguçadoura, Portugal in approximately 45 m of water (previously the Aguçadoura Wave Farm site). The WindFloat was fitted with a Vestas V80 2.0-MW 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's being towed offshore. This is the first offshore wind turbine installed in open Atlantic waters, and the first to employ a semi-submersible type floating foundation.[better source needed]
SeaTwirl deployed its first floating grid connected wind turbine off the coast of Sweden in August 2011. It was tested and de-commissioned. This design intends to store energy in a flywheel. Thus, energy could be produced even after the wind has stopped blowing.
Blue H Technologies
Blue H Technologies of the Netherlands operated the first floating wind turbine, a prototype deep-water platform with an 80-kilowatt turbine off the coast of Apulia, southeast Italy, in 2008. 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.
The Blue H technology utilized a tension-leg platform design and a two-bladed turbine. The two-bladed design can have a "much larger chord, which allows a higher tip speed than those of three-bladers.
As of 2009[update], 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.
The world's first operational deep-water floating large-capacity wind turbine is the Hywind, in the North Sea off Norway. The Hywind was towed out to sea in early June 2009. 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.
The installation is owned by Statoil and will be tested for two years. 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." 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." The unit became operational in the summer of 2009. Hywind was inaugurated on 8 September 2009. As of October 2010[update], after a full year of operation, the Hywind turbine is still operating and generating electricity for the Norwegian grid, and still is as of December 2014.
The turbine cost 400 million kroner (around US$62 million) to build and deploy. 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. The installation is expected to generate about 9 GW·h of electricity annually. The SWATH (Small Waterplane Area Twin Hull) offshore wind turbine service boat, will be tested at Hywind.
Hywind delivered 7.3 GWh in 2010, and survived 11 meter waves with seemingly no wear.
Statoil considers moving the Hywind from Karmøy to a gas platform, reducing gas turbine use.
In 2013, Statoil pulled out of the $120 million project of four 3-MW turbines floating in 460 feet of water near Boothbay Harbor, Maine citing change in legislation, and focused on their five 6-MW turbines in Scotland instead, where the average wind speed is 10 m/s and the water depth is 100m. The UMaine Aqua Ventus project continues.
In 2015, Statoil received permission to install 30MW Hywinds 18 miles (29 km) outside Peterhead in Scotland, operational around 2017, and plans to test a 1 MWh lithium-ion battery system (called Batwind) with the Hywinds.
Construction of the NOK 2 billion (£152m) project started in 2016 in Spain, Norway and Scotland. Three suction cup anchors will hold each turbine. Plans are to assemble the elements near Stord in summer 2017 and then drag them to Peterhead.
WindFloat is a floating foundation for offshore wind turbines designed and patented by Principle Power. A full-scale prototype was constructed in 2011 by Windplus, a joint-venture between EDP, Repsol, Principle Power, A. Silva Matos, Inovcapital, and FAI. The complete system was assembled and commissioned onshore including the turbine. The entire structure was then wet-towed some 400 kilometres (250 mi) (from southern to northern Portugal) to its final installed location 5 kilometres (3.1 mi) offshore of Aguçadoura, Portugal, previously the Aguçadoura Wave Farm. The WindFloat was equipped with a Vestas v80 2.0-megawatt turbine and installation was completed on 22 October 2011. A year later, the turbine had produced 3 GWh.
The subsea metal structure is reported to improve dynamic stability, whilst still maintaining shallow draft, by dampening wave– and turbine–induced motion utilizing a tri-column triangular platform with the wind turbine positioned on one of the three columns. The triangular platform is then "moored" using a conventional catenary mooring consisting of four lines, two of which are connected to the column supporting the turbine, thus creating an "asymmetric mooring."
As the wind shifts direction and changes the loads on the turbine and foundation, a secondary hull-trim system shifts ballast water between each of the three columns. This permits the platform to maintain even keel while producing the maximum amount of energy. This is in contrast to other floating concepts which have implemented control strategies that de-power the turbine to compensate for changes in turbine thrust-induced overturning moment.
This technology could allow wind turbines to be sited in offshore areas that were previously considered inaccessible, areas having water depth exceeding 40 metres and more powerful wind resources than shallow-water offshore wind farms typically encounter.
The cost of this project is around €20 million (about US $26 million). This single wind turbine can produce energy to power 1300 homes.
Platform topologies can be classified into:
- single-turbine-floater (one wind turbine mounted on a floating structure)
- multiple turbine floaters (multiple wind turbines mounted on a floating structure)
Undersea mooring of floating wind turbines is accomplished with three principal mooring systems. Two common types of engineered design for anchoring floating structures include tension-leg and catenary loose mooring systems. 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." 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.
The IEC 61400–3 design standard requires that a loads analysis be based on site-specific external conditions such as wind, wave and currents. The IEC 61400–3-2 standard applies specifically to floating wind turbines.
The technical feasibility of deepwater floating wind turbines is not questioned, as the long-term survivability of floating structures has 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 marine-proofed 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).
As of 2009[update] 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 since the late 1990s, 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.
As of 2009[update], the practical feasibility and per-unit economics of deep-water, floating-turbine offshore wind is yet to be established. Initial deployment of single full-capacity turbines in deep-water locations began only in 2009.
As of October 2010[update], 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 coastline of the UK where winds are stronger and reliable."
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. A significant challenge when using this approach is the coordination needed to develop transmission lines.
- Oil well injection
When oil fields become depleted, the operator injects water to keep pressure high for further extraction. This requires power, but installing gas turbines means shutting down the extraction process, losing valuable income. The classification society DNV GL has calculated that in some cases a floating wind turbine can economically provide power for injection, as the oil platform can keep on producing, avoiding a costly pause.
In 2016 DNV GL, ExxonMobil and others approved calculations of saving $3/barrel of oil using a 6MW Hywind instead of traditional engines, driving two 2MW pumps injecting water into an offshore oil well. At least 44,000 barrels of processed water per day can be injected, even on calm June days.
Floating design concepts
Ideol’s engineers have developed and patented a ring-shaped floating foundation based on a central opening system (Damping Pool) used for optimizing foundation + wind turbine stability. As such, the sloshing water contained in this central opening counteracts the swell-induced floater oscillations. Foundation-fastened mooring lines are simply attached to the seabed to hold the assembly in position. This floating foundation is compatible with all wind turbines without any modification and has reduced dimensions (from 36 to 55 meters per side for a wind turbine between 2 and 8 MW). Manufacturable in concrete or steel, this floating foundation allows for local construction near project sites. Ideol leads the FLOATGEN project, a floating wind turbine demonstration project based on Ideol’s technology and planned to be built by Bouygues Travaux Publics and installed by mid-2017 off the coast of Le Croisic on the offshore experimentation site of Ecole Centrale de Nantes (SEM-REV). The construction of this project, France's first offshore wind turbine (precisely 2 MW), is already underway since the 1st of June 2016.
In June 2015, the company has sealed its first commercial contract with the Japanese conglomerate Hitachi Zosen, for the design of the two latest Japanese floating offshore wind demonstrators. In July 2016, Ideol and Hitachi Zosen and Ideol have signed a contract launching the construction phase of their 2 floating offshore wind turbines. These 2 floaters will be each manufactured with different materials (concrete and steel), will be equipped with different wind turbines and will be anchored using different mooring line materials.
In late 2015, Ideol also announced the conclusion of a preliminary collaboration with China Steel Corporation aiming at designing and engineering floating offshore wind turbines.
The French government  has recently selected Eolmed, a consortium led by Quadran in association with Ideol, Bouygues Travaux Publics and Senvion, a french renewable energy developer, for the development and construction of a 25MW Mediterranean floating offshore wind farm 15 km off the coastal town of Gruissan (Languedoc-Roussillon).
Nautica Windpower has proposed a technique for potentially reducing system weight, complexity and costs for deepwater sites. Scale model tests in open water have been conducted (September 2007) in Lake Erie and structural dynamics modeling was done in 2010 for larger designs. 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.
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.
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 20 MW. The program is supported with €3m through EUs Seventh Framework Programme. Partners include TUDelft, Aalborg University, SINTEF, Statoil and United States National Renewable Energy Laboratory.
North America’s first floating grid-connected wind turbine was lowered into the Penobscot River in Maine on 31 May 2013 by the University of Maine Advanced Structures and Composites Center and its partners.[needs update] The VolturnUS 1:8 was towed down the Penobscot River where it was deployed for 18 months in Castine, ME. During its deployment, it experienced numerous storm events representative of design environmental conditions prescribed by the American Bureau of Shipping (ABS) Guide for Building and Classing Floating Offshore Wind Turbines, 2013.
The patent-pending, VolturnUS floating concrete hull technology can support wind turbines in water depths of 45 meters or more, and has the potential to significantly reduce the cost of offshore wind. With 12 independent cost estimates from around the U.S. and the world, it has been found to significantly reduce costs compared to existing floating systems. The design has also received a complete third-party engineering review.
In June 2016, the UMaine-led New England Aqua Ventus I project won top tier status from the US Department of Energy (DOE) Advanced Technology Demonstration Program for Offshore Wind. This means that the Aqua Ventus project is now automatically eligible for an additional $39.9 Million in construction funding from the DOE, as long as the project continues to meet its milestones. The developer asserts that the Aqua Ventus project will likely become the first commercial scale floating wind project in the Americas.
VertiWind is a floating Vertical Axis Wind Turbine design created by Nenuphar [full citation needed] whose mooring system and floater are designed by Technip.[full citation needed][non-primary source needed]
An open source project was proposed by former Siemens director Henrik Stiesdal in 2015 to be assessed by DNV GL. It suggests using tension leg platforms with replaceable pressurized tanks anchored to sheet walls.
Floating wind farms
As of September 2011[update], 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. After the evaluation phase is complete in 2016, "Japan plans to build as many as 80 floating wind turbines off Fukushima by 2020." 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. Some foreign companies also plan to bid on the 1-GW large floating wind farm that Japan hopes to build by 2020. In March 2012, Japan’s Ministry of Economy, Trade and Industry approved a 12.5bn yen ($154m) project to float a 2-MW Fuji in March 2013 and two 7-MW 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 519 GW of floating offshore wind capacity in Japan. The first turbine became operational in November 2013. 
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. [needs update]
In April 2012 Statoil received state regulatory approval to build a large four-unit demonstration wind farm off the coast of Maine. As of April 2013[update], the Hywind 2 4-tower, 12–15 MW wind farm was being developed by Statoil North America for placement 20 kilometres (12 mi) off the east coast of Maine in 140–158 metres (459–518 ft)-deep water of the Atlantic Ocean. Like the first Hywind installation off Norway, the turbine foundation will be a spar floater. The State of Maine Public Utility Commission voted to approve the construction and fund the US$120 million project by adding approximately 75 cents/month to the average retail electricity consumer. Power could be flowing into the grid no earlier than 2016.
As a result of legislation in 2013 (LD 1472) by the State of Maine, Statoil placed the planned Hywind Maine floating wind turbine development project on hold in July 2013. The legislation required the Maine Public Utilities Commission to undertake a second round of bidding for the offshore wind sites with a different set of ground rules, which subsequently led Statoil to suspend due to increased uncertainty and risk in the project. Statoil is considering other locations for its initial US demonstration project.
Some vendors who could bid on the proposed project in Maine expressed concerns in 2010 about dealing with the United States regulatory environment. Since the proposed site is in Federal waters, developers would need a permit from the US 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."
Scale modeling and computer modeling attempt to predict the behavior of large–scale wind turbines in order to avoid costly failures and to expand the use of offshore wind power from fixed to floating foundations. Topics for research in this field include:
- Overview of integrated dynamic calculations for floating offshore wind turbines
- Fully coupled aerohydro-servo-elastic response; a basic research tool to validate new designs
- Water tank studies on 1:100 scale Tension-leg Platform and Spar Buoy platforms
- Dynamic response dependency on the mooring configuration[full citation needed]
As they are suitable for towing, floating wind turbine units can be relocated to any location on the sea without much additional cost. So they can be used as prototype test units to practically assess the design adequacy and wind power potential of prospective sites.
Floating wind turbines can be used to provide motive power for achieving artificial upwelling of nutrient-rich deep ocean water to the surface for enhancing fisheries growth in areas with tropical and temperate weather. Though deep seawater (below 50 meters depth) is rich in nutrients such as nitrogen and phosphorus, the phytoplankton growth is poor due to the absence of sunlight. The most productive ocean fishing grounds are located in cold water seas at high latitudes where natural upwelling of deep sea water occurs due to inverse thermocline temperatures. The electricity generated by the floating wind turbine would be used to drive high–flow and low–head water pumps to draw cold water from below 50 meters water depth and mixed with warm surface water by eductors before releasing into the sea. Mediterranean sea, Black sea, Caspian sea, Red sea, Persian gulf, deep water lakes/reservoirs are suitable for artificial upwelling for enhancing fish catch economically. These units can also be mobile type to utilise the seasonal favourable winds all around the year.
- Laskow, Sarah (13 September 2011). "Hope Floats for a New Generation of Deep-Water Wind Farms". Good Environment. Retrieved 12 October 2011.
- Mark Svenvold (9 September 2009). "The world's first floating wind turbine goes on line in Norway". DailyFinance.com. Retrieved 20 October 2009.
- Union of Concerned Scientists (15 July 2003). "Farming the Wind: Wind Power and Agriculture". Retrieved 20 October 2009.
- Musial, W.; S. Butterfield; A. Boone (November 2003). "Feasibility of Floating Platform Systems for Wind Turbines" (PDF). NREL preprint. NREL (NREL/CP-500-34874): 14. Retrieved 10 September 2009.
- KASPER BRØNDGAARD ANDERSEN. "Industrien: Vindmøller skal ud, hvor de ikke kan bunde" EnergiWatch, 25 July 2013. Accessed: 17 October 2013
- Nation's first floating wind turbine launched, retrieved 2016-07-05
- "VolturnUS 1:8 windturbine launches in 2013". Retrieved 2016-07-05.
- "DeepCwind Consortium | Advanced Structures & Composites Center | University of Maine". composites.umaine.edu. Retrieved 2016-07-05.
- "Maine Offshore Wind Project Moves to Top Tier of National Offshore Wind Demonstration Program". U.S. Senator Susan Collins. United States Senate. Retrieved 5 July 2016.
- 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
- Madslien, Jorn (8 September 2009). "Floating challenge for offshore wind turbine". BBC News. Retrieved 14 September 2009.
- Deep water wind turbines, The Institution of Engineering and Technology, 18 October 2010, accessed 6 November 2011 Archived 26 November 2010 at the Wayback Machine.
- "First WindFloat Successfully Deployed Offshore". 30 November 2011.
- "Teknisk fysik". Chalmers.se. Retrieved 2 December 2013.
- Patel, Prachi (22 June 2009). "Floating Wind Turbines to Be Tested". IEEE Spectrum. Retrieved 25 June 2009.
- Ramsey Cox (February–March 2010). "Water Power + Wind Power = Win!". Mother Earth News. Retrieved 3 May 2010.
- Madslien, Jorn (5 June 2009). "Floating wind turbine launched". BBC News. Retrieved 14 September 2009.
- Jensen, Mette Buck. Vestas goes for floating wind turbines (in Danish) Ing.dk, 14 September 2009. Retrieved: 11 November 2010
- "StatoilHydro inaugurates floating wind turbine". Statoil.com. Retrieved 2 December 2013.
- "First offshore wind turbine goes to sea". UPI. 6 June 2009. Retrieved 2009-06-07.
- "Technip and StatoilHydro Announce Inauguration of World's First Full-Scale Floating Wind Turbine". OilVoice. 13 September 2009. Retrieved 19 September 2009.
- "Hywind floating wind turbine". Statoil. 8 September 2009. Retrieved 29 September 2009.
- 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
- Wittrup, Sanne. "Finnerne får deres første havmøllepark" Ingeniøren, 11 December 2014. Accessed: 11 December 2014
- "Statoil Draws On Offshore Oil Expertise To Develop World's First Floating Wind Turbine". NewTechnology magazine. 8 September 2009. Retrieved 21 October 2009.
- Turker, Tux (19 May 2009). "Maine task force to identify offshore wind energy sites". Energy Current. Retrieved 7 June 2009.[dead link]
- Donovan, Matthew (11 August 2009). "Subsea cable installed at Hywind project". Energy Current. Retrieved 2 September 2009.[dead link]
- 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.
- Stensvold, Tore. Delivery of first wind turbine boat (in Norwegian) Weekly Technicals, 10 November 2010. Retrieved: 16 November 2010
- Nilsen, Jannicke. Statoil wants Hywind in Japan Teknisk Ukeblad, 4 April 2011. Accessed: 4 April 2011
- Garrett, Paul (24 June 2011). "Scotland and US next pilot sites for Hywind floating project". Windpower Monthly. Retrieved 27 September 2011.
- Tux Turkel. "Statoil leaving Maine for more certain climate (page 1)" Page 2 Portland Press Herald, 15 October 2013. Accessed: 17 October 2013
- Sue Mello. "Statoil pulls out" Boothbay Register, 15 October 2013. Accessed: 17 October 2013
- Whit Richardson. "Statoil to quit work on $120 million offshore wind project in Maine" Bangor Daily News, 15 October 2013. Accessed: 17 October 2013
- THOMAS BO CHRISTENSEN. "Statoils amerikanske flydemøller blæst omkuld" EnergiWatch, 15 October 2013. Accessed: 17 October 2013
- "Hywind 2 Demonstration (UK) 30 MW", 4C. Accessed: 17 October 2013
- Simon Hadley. "Statoil floats Scottish plans" UK offshore wind. Accessed: 17 October 2013
- Nick McCrea. "UMaine submits bid for floating wind turbine deal" Bangor Daily News, 3 September 2013. Accessed: 17 October 2013
- Video on YouTube
- Nilsen, Jannicke. Statoil utvikler eget batteri-system for lagring av vindkraft Teknisk Ukeblad, 21 March 2016. Accessed: 21 March 2016
- Jannicke Nilsen. "Sjekk dimensjonene: Disse kjettingene skal feste Statoils flytende vindmølle til havbunnen". Teknisk Ukeblad. Retrieved 20 April 2016.
- Shankleman, Jessica. Vestas floats plan for WindPlus offshore demo Business Green, 18 February 2011. Accessed: 23 February 2011
- Snieckus, Darius (18 December 2012). "Principle Power lands $43m funding double for WindFloat". RechargeNews. Retrieved 21 December 2012.
- "Vestas, WindPlus to deploy floating wind turbine structure". Composites World. 21 February 2011. Retrieved 2 December 2013.
- Balogh, Emily (18 December 2008). "Deepwater Offshore Wind Power Generation Using Oil and Gas Platform Technology". RenewableEnergyWorld.com. Retrieved 3 September 2009.
- 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."
- "Principle Power & EDP to Develop Floating Offshore Wind". RenewableEnergyWorld.com. 20 February 2009. Retrieved 3 September 2009.
- "Principle Power & EDP to Develop Floating Offshore Wind". expresso.sapo.pt. 28 February 2013. Retrieved 28 February 2013.
- Ros Davidson. "Floating turbines planned for US west coast" Windpower Offshore, 14 October 2013. Accessed: 23 November 2013
- Japanese floater gets relocated 4C, 21 April 2016
- Jonkman, J.M. "Dynamics Modeling and Loads Analysis of an Offshore Floating Wind Turbine" Technical Report NREL/TP-500-41958, NREL November 2007. Retrieved 25 June 2012
- Floating Offshore Wind Turbines: Responses in a Seastate -- Pareto Optimal Designs and Economic Assessment, P. Sclavounos et al, October 2007
- "IEC - TC 88 Dashboard > Projects: Work programme, Publications, Maintenance cycle, Project files, TC/SC in figures". Iec.ch. 15 October 2010. Retrieved 2 December 2013.
- "Classification and Certification of Floating Offshore Wind Turbines" (PDF). Veristar.com. Retrieved 2 December 2013.
- "Floating turbines promise to deliver reliable wind, says report | Environment". theguardian.com. Retrieved 2 December 2013.
- Lie, Øyvind. "Energi 21 vil ha Hywind til Norge" Teknisk Ukeblad, 11 April 2014. Accessed: 11 December 2014
- Haugstad, Øyvind. "Fiasko for norsk havvind" Teknisk Ukeblad, 22 May 2014. Accessed: 11 December 2014
- Floating Offshore Wind Market Technology Review Carbon Trust
- Nilsen, Jannicke. "DNV GL: Nå kan det lønne seg med flytende havvind til oljeplattformer" In English Teknisk Ukeblad, 20 January 2015. Accessed: 22 January 2015
- "DNV GL-led project gives green light for wind-powered oil recovery". DNV GL. Retrieved 4 May 2016.
- Tormod Haugstad. "Snart kan oljeselskapene få strøm fra flytende havvind - kan spare 3 dollar fatet". Teknisk Ukeblad. Retrieved 4 May 2016.
- Win-Win floating wind concept 'feasible' for oil & gas developments (paywall)
- "Senvion Turbines to Float off French Mediterranean Coast". Offshore Wind. Retrieved 1 August 2016.
- Braciszeski, Kevin (23 January 2010). "Why Not Floating Windmills?". Ludington Daily News. Archived from the original on 14 July 2011. Retrieved 8 February 2010.
- "US Offshore Wind Energy: A Path Forward" (PDF). Working Paper page 24. US Offshore Wind Collaborative. 16 October 2009. Retrieved 7 November 2009.
- 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 11 September 2010
- Stage, Mie (11 November 2010). "Risø floats 20MW" (in Danish). Ingeniøren. Retrieved 17 January 2011.
- DeepWind Risø, sourcedate. Retrieved: 11 November 2010
- Munck, Susanne. Future turbines Risø, Danish, 8 November 2010. Retrieved: 11 November 2010
- Danko, Pete. "First US Floating Wind Turbine Launches In Maine". EarthTechling. Retrieved 2 December 2013.
- "Renewable energy: Wind power tests the waters". Nature News & Comment.
- "VolturnUS 1:8". UMaine Advanced Structures and Composites Center. University of Maine. Retrieved 5 July 2016.
- "New England Aqua Ventus I Selected by the DOE for up to $39.9 Million in Additional Funding | Advanced Structures & Composites Center | University of Maine". composites.umaine.edu. Retrieved 2016-07-05.
- "Nenuphar :: Accueil". Nenuphar-wind.com. Retrieved 2 December 2013.
- "Technip". Retrieved 2 December 2013.
- "Numerical Study on the Motions of the VertiWind Floating Offshore Wind Turbine" (PDF). Retrieved 10 December 2013.
- "Vindmøllepioner: 'Open source'-tilgang kan give førerposition på havmøllefundamenter" ['Open source' approach can provide leadership in offshore foundations]. Ingeniøren.
- in English
- "Wind maverick Stiesdal launches cost-slashing floating foundation design". rechargenews.com.
- "Japan Plans Floating Wind Power Plant". Breakbulk. 16 September 2011. Retrieved 12 October 2011.
- Annette Bossler. "Floating turbines - Japan enters the stage" OffshoreWind, 12 September 2013. Accessed: 17 October 2013
- Yoko Kubota Japan plans floating wind power for Fukushima coast Reuters, 13 September 2011. Accessed: 19 September 2011
- Quilter, James (1 November 2011). "Statoil looks to Japan with Hywind concept". WindPower Monthly. Retrieved 1 December 2011.
- Patton, Dominique. Mitsubishi and Fuji named for Fukushima offshore wind farm Recharge News, 6 March 2012. Accessed: 8 March 2012
- Elaine Kurtenbach. "Japan starts up offshore wind farm near Fukushima" The Sydney Morning Herald, 12 November 2013. Accessed: 11 November 2013
- "Japan: Experimental Offshore Floating Wind Farm Project" OffshoreWind, 11 October 2013. Accessed: 12 October 2013
- Maine seeks 30MW of offshore wind and tidal pilots, BrighterEnergy.org, 3 September 2010, accessed 12 September 2010
- State point man on offshore wind clearly energized, Maine Sunday Telegram, 6 June 2010, accessed 13 June 2010: "In September, the state plans to send out bids to build the world's first floating, commercial wind farm off the Maine coast."
- Hampton, Stuart (30 April 2012). "Statoil to demonstrate floating offshore wind turbines in the US". Bizmology. Hoovers. Retrieved 20 May 2012.
Statoil has secured the support of government officials in Maine to develop a demonstration wind park in the US with four full-scale offshore wind turbines.
- "Hywind 2 Demonstration (Maine)". Offshore Wind Farms Project Database. 4C Offshore. Retrieved 3 April 2013.
- "Pioneering Maine wind project passes 'biggest hurdle'". Portland Press Herald. 25 January 2013. Retrieved 3 April 2013.
- "USA: Statoil Freezes Hywind Maine Project". OffshoreWind.biz. 5 July 2013. Retrieved 2 August 2013.
- Andrew Cordle (GL Garrad Hassan) & Jason Jonkman (NREL). "State of the Art in Floating Wind Turbine Design Tools" NREL/CP-5000-50543, NREL October 2011. Retrieved 25 June 2012
- Naqvi, Syed Kazim. "Scale model experiments on floating offshore wind turbines" Worcester Polytechnic Institute, May 2012. Retrieved 25 June 2012
- [dead link]
- "Enhancing fish stocks with artificial upwelling" (PDF). Retrieved 7 May 2015.
- Torsten Thomas: Solutions for floating foundations. In: Ship & Offshore, No. 5/2014, p 30–33, DVV Media Group, Hamburg 2014, ISSN 2191-0057
|Wikimedia Commons has media related to Floating wind turbines.|
- Floating Offshore Wind Foundations: Industry Consortia and Projects in the United States, Europe and Japan industry report, 2013 edition
- Far Offshore Renewables: www.faroffre.com
- Sway, (in Norwegian Sway (company))
- Nancy Stauffer (MIT): Giant wind turbines, floating out of sight. 2006 preliminary design with 5 MWe turbine units mounted 90 metres above the sea with massive 140-metre-diameter blades; MIT-NREL design.
- Principle Power: WindFloat
- Statoil: Hywind floating wind turbine
- PelaStar: PelaStar TLP
- Nautica Windpower: Floating wind turbine system
- Floating Support Structures: LORC Knowledge