Enova will provide the Bergen-based company Sway AS with funding in the amount of NOK 137 million to demonstrate a new 10 Megawatt wind turbine prototype. The project represents a significant potential reduction in the cost of generating offshore wind power.
The funding from Enova will contribute to the construction of a 10 MW wind turbine in Øygarden in Hordaland County, where the new technology will be tested on land over the next two years. The wind turbine will be the world’s largest of its kind, with a rotor diameter of 145 metres. In cooperation with the Norwegian technology firm Smartmotor AS, Sway has developed the concept with a view towards reducing turbine weight and the number of moving parts, as well as the use of a gearless generator system. Overall, the concept will result in higher energy generation for offshore wind power, and thus also lower operating costs. As many as 35-40 engineers have taken part in the work to develop the concept that will now undergo testing.
The SWAY system is a viable solution for the electrification of oil & gas platforms with electricity production costs, including capital costs, well below the operational costs alone for the gas and diesel turbines used currently in the offshore industry. A detailed case study for the integration of wind power to an oil platform off the coast of Norway was successfully completed in 2004. The study concludes that it is both technically and economically feasible to integrate wind power with the existing gas and diesel generators on the offshore oil & gas platforms. The benefits of this integration would be savingsin the form of lower electricity costs and reduced emissions.
Wind power production can be more efficient in deep water locations due to the presence of consistently higher average wind speeds. At 50 km off the coast of Norway, where the water depth is typically between 100-300m, the power production from each wind turbine would be 20-30% higher than the same wind turbine located at the Horn’s Reef installation situated some 15 km off the west coast of Denmark. This improvement is simply due to the greater and more consistent winds further offshore.
The patented SWAY system is based on a floating tower which extends far below the water surface. The tower consists of a floating pole with ballast in the lower end, similar to a floating bottle. The tower, which is filled with ballast, has its center of gravity located far below the center of buoyancy of the tower. This gives the tower sufficient stability to resist the large loads produced by the wind turbine mounted on top of it.
The floating tower is anchored to the seabed with a single pipe and a suction anchor. When the wind hits the rotor the tower is tilting some 5-8 degrees. By tilting the rotor the opposite way which is made possible by placing the rotor downwind of the tower the rotor is kept perfectly aligned with the wind.When the wind changes direction, the entire tower turns around a subsea swivel. This, in turn, makes it possible to reinforce the tower with a tension rod system similar to wire stays on a sailboat mast. Due to the resulting reduction of stresses in the tower, the tower is capable of carrying a much larger turbine, which greatly enhances the total economy.