Progress in the development of commercially-viable direct drive wind turbines took a significant step forward last week, with the official launch by Siemens Energy of its SWT-3.0-101 wind turbine. This turbine has a faceplate rating of 3 MW, has no gearbox and uses a permanent magnet generator to produce electricity. What’s really interesting about this system is that according to Henrik Stiesdal, Chief Technology Officer for the Siemens WInd Power business unit, the turbine produces 25% more power than the Siemens 2.3 MW machine – but does so with less weight and only 50% of the parts! The nacelle which contains the machinery at the top of the tower, weighs just 73 tonnes. Because of its compact size, the nacelle can be transported using fairly standard vehicles.
There has been much interest in the development of direct drive systems in recent years, since the elimination of the gear box theoretically the turbine system more reliable. What Siemens appears to have done is to take that a step further – by eliminating half of the components at the top of the tower, there is less maintenance for the service technicians to have to worry about. This is good for onshore systems, but even more valuable for wind turbines that are to be located offshore, far from land. It also means, in theory, more uptime for each turbine, thus allowing them to produce electricity over wider intervals.
Siemens installed the first prototype of the SWT-3.0-101 at the beginning of December 2009 close to the town of Brande in Denmark. Siemens entered the wind energy business through the acquisition of the Danish company Bonus Energy A/S approximately five years ago, a company that had been in business since 1980, as Danregn Vindkraft. This company was a pioneer in the early days of recent interest in wind power, and was a logical acquisition for Siemens as it looked to enter the market. The Siemens Wind Power business unit is still headquartered in Brande. The permanent magnet generator is being produced by the Large Drives business unit within the Siemens Industry Sector.
Siemens first tested direct drive systems in the form of two 3.6 MW concept turbines in July 2008, leading to the 3.0 MW prototype installed late last year. While Siemens acknowledges that they were not the first to market with a direct drive permanent magnet generator system, the company appears to have deliberately taken its time with the development of its own systems. In a news release from late last year, Mr. Stiesdal indicated that rushing to the market with immature technology was not an option for Siemens. While the nacelle contains new technology, the blades, rotor hub, tower and controller were developed from existing products. Full commercial launch of the new turbine through serial production, is expected to commence next year, with a number of systems being installed around the world in the meantime.
One comment from Siemens is worthy of note for the permanent magnet industry and its supply chain. In a promotional video that was released to coincide with the launch of the new turbine, Ernst Frendesen, Director of Global Sales and Proposals for Siemens said that the
“market demand that we expect on this machine will be extremely big and therefore for a period, we think that the market demand will outweigh the production capacity.”
Attempts to ascertain the specific amount of permanent magnet materials used in SWT-3.0-101 turbine design were declined by the company for reasons of confidentiality. It is clear, however, that Siemens is putting the permanent magnet industry [and indirectly, the rare earths supply chain] on notice.
Mr. Stiesdal has kindly agreed to do an interview with me on the SWT-3.0-101 wind turbine and its direct drive, permanent magnet-based drive system, which I will post to Terra Magnetica once completed, along with any other developments in the area of DD PMG turbines as they happen.
[last updated August 9, 2010, to correct text of Mr. Frendesen's quote from promotional video].