Sway Turbine unveils 10MW design

Distinctive 'bicycle wheel' style for ST10

Since 2010, Norwegian wind technology company, Sway Turbine (ST), has been part of a global race to produce the world's first 10MW wind turbine. Unveiling its design, ST’s 10MW machine features a 25m spoke-type, direct drive, permanent magnet generator (PMG).

Designed for demanding conditions, the ST10’s specifications include a 164m rotor diameter with three rotor blade supports (eliminating the need for a rotor hub), a 13m/s rated wind speed, and 12rpm nominal speed.

The next step for ST is to identify an industrial partner with which it can collaborate to bring the ST10 to market. As recently explored by Windpower Offshore, Norwegian companies’ involvement in the offshore wind market is export driven, due to the government’s decision not to prioritise construction of offshore wind capacity in its own waters.

Development of the ST10 began in 2005 with the aim of finding a cost-effective, low-weight solution for floating turbines and overcoming key challenges associated with turbine upscaling. However, the ST10 is designed for fixed-bottom foundations.

What immediately catches the eye about the turbine is its open generator, which resembles a large bicycle wheel, including rim, spokes and two central bearing housings. The comparison stops there, though, as the ‘rim’ is the axial flux generator incorporating the rotor and stator. The stator, supported by the inner spokes, is sandwiched in between two rotating rotor disks. Supported by thick spokes, the rotor disks are fitted with inward-facing permanent magnets.

Explaining the ST10’s unusual design and its advantages over ‘conventional’ offshore wind turbines, ST co-founder and chief technical officer, Eystein Borgen, said: "Our custom-designed blade for 164m rotor diameter and 10m/s mean wind speed sites … offers the best CoE performance, but additional rotor sizes serving different wind speed conditions are possible."

He added that "the103m/s rated tip speed is higher but not the highest in industry and we will apply special erosion-resistant material for the rounded leading edge. Finally, aerodynamic noise is normally not an issue offshore, while we benefit from 10–14% higher generator yields compared to 90-95 m/s tip speeds and similar power rating."

For more details about the ST10 design, please see the full article published by Windpower Offshore’s sister brand, Windpower Monthly.

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