The vision for large-scale offshore floating wind turbines was introduced by Professor William E. Heronemus at the University of Massachusetts in 1972, but it was not until the mid 1990’s, after the commercial wind industry was well established, that the topic was taken up again by the mainstream research community. Current fixed-bottom technology has seen limited deployment to water depths of 20 m. As the technology is advanced into deeper water, floating wind turbine platforms maybe the most economical means for deploying offshore wind turbines in deep water .Worldwide, the offshore wind resource has been shown to be extremely abundant, Technically, the 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 oilrigs have yet to be demonstrated for floating wind turbine platforms. For deepwater wind turbines, a floating structure may replace driven monopoles or conventional concrete gravity bases that are commonly used as foundations for shallow water turbines. A 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 turbine design philosophy for floating may be impacted if platform dynamics require a more dynamically compliant machine but the platform costs are likely to dominate the cost tradeoffs. Therefore, it is assumed that 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, close proximity to large load centers (e.g. shorter transmission runs), and greater public acceptance due to lower visual and environmental impacts. Energy models indicate that if platform costs can be held near 25% of the total system capital cost.
1.1 Floating Wind Turbine
The emerging need for renewable and environmentally friendly sources of energy has led to a recent and growing interest towards the development of floating offshore wind turbine technologies which may be deployed in water depths of up to 300 m for the cost-effective generation of electricity. Some advantages of operating in the offshore environment include higher and steadier wind speeds, less-restrictive acoustic requirements, and fewer space constraints. This research draws upon the experience of the oil/gas and wind industries respectively and studies the coupled dynamics of tethered and moored floating wind turbine technologies.
Fig. 1.1 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 whilst 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. 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. The offshore wind industry has experienced significant growth in re-cent years, and continues to expand worldwide. Nearly all of the off-shore wind turbines installed to date are located in North European Seas and are mounted on fixed-bottom support structures in water depths of 35 m or less. There are a limited number of suitable shallow water sites available in offshore locations for countries currently active in offshore wind. Much of the global offshore wind resource is in locations where the water is much deeper than it is at the sites of current installations. The offshore resources also exist where fixed-bottom support...
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 Laskow, Sarah (2011-09-13). "Hope Floats for a New Generation of Deep-Water Wind Farms". Good Environment. Retrieved 2011-10-12.
 Mark Svenvold (2009-09-09). "The world 's first floating wind turbine goes on line in Norway". DailyFinance.com. Retrieved 2009-10-20.
 Union of Concerned Scientists (2003-07-15). "Farming the Wind: Wind Power and Agriculture". Retrieved 2009-10-20.
 Musial, W.; S. Butterfield, A. Boone (2003-11). "Feasibility of Floating Platform Systems for Wind Turbines". NREL preprint (NREL) (NREL/CP-500-34874): 14. Retrieved 2009-09-10.
 New Technology magazine, Statoil Draws On Offshore Oil Expertise To Develop World 's First Floating Wind Turbine.. 2009-09-08. Retrieved 2009-10-21.
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