Six-Megawatt Wind Turbine without Gearbox

The turbine has an output of six megawatts (MW) and low maintenance requirements. Altogether, the nacelle and the rotor blades (with a rotor diameter of 120 meters) weigh less than 350 metric tons.

Moreover, the turbine is fitted with an innovative direct drive and therefore does not require a gearbox. Trials to assess its performance and availability are now being conducted on a prototype installed off the Danish coast. If everything proceeds according to schedule, the SWT-6.0-120 wind turbine should enter series production in 2014.

To date, high-output wind turbines have tended to be disproportionately heavy compared to systems of a lower rating. The SWT-6.0-120, by contrast, weighs only as much as a conventional wind turbine in the 2–3 MW category. What’s more, the use of extremely strong construction techniques has reduced the cost of the turbine itself as well as of the tower and the foundations. This in turn will further lower the cost of power generated by offshore wind turbines.

Experts from Siemens Wind Power in Denmark have developed a wind turbine that is capable of meeting the challenging conditions offshore. For a start, an ingenious but simple design has substantially reduced the number of rotating parts. In addition, the turbine features key technologies that have already proven their worth in the 3.6 MW variant of the turbine. For example, the initial production series of the turbine is to be fitted with B58-type rotor blades. These are manufactured by Siemens using the patented IntegralBlade process, which means they are poured in one cast and do not have any seams or bonded joints. The SWT-6.0-120 is also designed for easy servicing and low maintenance. This includes safer and simple access via a service platform mounted at the rear of the nacelle, to which technicians can be lowered from a helicopter. At the same time, enhanced diagnostic methods reduce the risk of downtime and increase the system’s reliability and therefore its availability. Siemens is to erect further prototypes of the 6 MW turbine in 2011 and carry out comprehensive trials. Moreover, in the course of the pilot production phase, additional turbines are to be installed over the next two years in order to enhance performance and reliability.

To date, Siemens has installed over 600 wind turbines in European waters, with a combined output of 1,800 MW. Wind turbine technology forms part of the Siemens environmental portfolio, which generated around €28 billion in sales for the company in fiscal 2010.