Siemens and StatoilHydro have launched a floating megawatt-class wind turbine, Hywind. (Earlier post.) The companies hope to use the research project to demonstrate that wind turbines that are not permanently anchored to the ocean floor can also make a significant contribution to the power supply.
|The Hywind floating wind turbine. Source: Siemens. Click to enlarge.|
The wind turbine is anchored in 220 meters of water roughly 12 kilometers southeast of the Norwegian island of Karmøy. Siemens provided the Hywind project with the electrical generating unit, which has a capacity of 2.3 megawatts (MW) and a rotor diameter of 82 meters. Hywind is scheduled to remain in trial operation for two years. The power it generates will be transported via undersea cable.
Hywind can be erected in water between 120 and 700 meters deep, thus expanding the operational area for offshore wind power. Current offshore units must be permanently anchored to the sear floor, and the cost of permanent foundations increases substantially at depths greater than 30 to 50 meters. As a result, countries with only very small, if any, shallow water zones off the coast are essentially prevented from erecting any wind power plants.
Calculations indicate that the wind power potential at distances up to 50 nautical miles from the US coastline is greater than the currently installed electrical generating capacity of all power plants in the US combined—more than 900 gigawatts.
StatoilHydro developed a ballast-filled steel buoy for use as the floating offshore foundation. The floating element extends as much as 100 meters below the surface of the water, from which depth it is anchored to the sea floor via three anchor cables. The partners also developed a special control system that enables the unit to offset the wave-induced motion of the floating foundation.