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SIEMENS

Research & Development
Technology Press and Innovation Communications

Dr. Ulrich Eberl
Herr Dr. Ulrich Eberl
  • Wittelsbacherplatz 2
  • 80333 Munich
  • Germany
Dr. Ulrich Eberl
Herr Florian Martini
  • Wittelsbacherplatz 2
  • 80333 Munich
  • Germany
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Siemens is developing new concepts for accelerating production of wind power facilities.

Siemens is developing new concepts for accelerating production of wind power facilities.

Siemens is developing new concepts for accelerating production of wind power facilities.

Siemens is developing new concepts for accelerating production of wind power facilities.

Siemens is developing new concepts for accelerating production of wind power facilities.

A New Spin on Production

Electricity generated from wind is still generally more expensive than power produced from coal. Siemens Wind Power plans to introduce industrial manufacturing processes across the board in order to make wind power more competitive and accelerate growth.

Siemens is developing new concepts for accelerating production of wind power facilities. For example, towers are now being built onsite from steel shells, robots will be used in the future to manufacture rotor blades, and many parts – such as nacelles – will be produced and delivered as modules. Wind power will become more competitive as a result.

Siemens Wind Power has set itself a clear goal: to lower the cost of generating one Kilowatt-hour (kWh) of onshore wind power to less than five euro cents by the end of the decade. That would put wind power on a par with traditional energy sources. By comparison, a kilowatt-hour of wind power now costs around seven cents, depending on the location in question. Siemens also believes the price of electricity produced by offshore facilities needs to be substantially reduced, since it’s currently around twice as high as the onshore price. The company’s target is therefore to lower the price to less than ten cents per kWh, which would make offshore wind power competitive.

With these goals in mind, Siemens Wind Power appointed Dr. Felix Ferlemann as CEO in October 2011. A mechanical engineer, Ferlemann worked in the automotive industry for more than ten years before joining Siemens. He was therefore more familiar with vacuum pumps, chassis, and transmissions than with generators or rotor blades. But it is exactly this kind of experience that Wind Power expects to benefit from, since the auto industry is ahead in some areas. “Along with continual innovation, the most effective way to reduce costs is to introduce industrial production processes,” says Ferlemann. “Over the last few decades, the auto industry has optimized vehicle components to such an extent that they can now be manufactured as cheaply as possible. The wind industry can learn a lot from such an approach.” Ferlemann’s concept is modeled on automotive platform strategies, modularization, standardization, and lean manufacturing processes.

The production of giant rotor blades for wind turbines offers a good example of how the wind energy sector can learn from the automotive industry. Siemens is the only company that manufacturers blades up to 75 meters long as a single component. Thanks to this patented Integral Blade Technology, the rotor blades have no seams, which means there are no weak points. As a result, they can reliably resist wind and weather for at least 20 years. However, rotor blade production is a very labor-intensive and drawn out process. Siemens employees in a 250-meter-long production hall in Aalborg, Denmark, currently lay out rotor blade molds with glass fiber mats and balsa wood by hand before the upper and lower halves are joined, evacuated, and filled with liquid epoxy resin. “Robots could lay out the molds just as well as humans,” says Ferlemann. “They’d also be much faster. They could run along the mold fully automatically and finish three meters each second. That would halve production time from 300 hours to 150 – and cut manufacturing costs by €30 million a year.”

Initial tests with a mold for a 40-meter-long rotor blade produced positive results, and plans now call for the first 55-meter-long blades to be manufactured with the help of robots in Aalborg as early as 2014. “We will use conventional industrial robots that will be specially programmed by our rotor blade production experts,” says Jan Rabe, Chief Strategist at Siemens Wind Power. “This will put us well ahead of the competition.”

But that will only be the first step. Siemens itself could also manufacture the made-to-measure mats for blade production directly from glass fiber in order to satisfy the special requirements associated with windmills. “Mats can be woven with varying thicknesses in accordance with their position in the rotor blade,” says Rabe. “If we were to take that into account during the manufacturing process, we could reduce the costs of the blades even further.”

Such approaches will be needed if the wind power sector is to continue the substantial growth it has achieved over the last few years. Sales at Siemens Wind Power alone have increased by around 40 percent each year since 2004, when Siemens acquired Bonus, a Danish manufacturer. At that time, Bonus was building approximately 200 wind turbines per year and posting annual sales of €300 million. Today, Siemens builds some 2,000 turbines each year and generates sales of €5 billion. The order volume currently stands at €11 billion. “Naturally, we initially had to focus on managing growth,” says Ferlemann, “but now we’re in a consolidation phase and need to increase productivity and reduce costs.”

Gearless Drives for Nacelles. This also applies to the production of wind power plant nacelles, which account for roughly 60 percent of manufacturing costs. The remainder is more or less equally divided between the tower and the rotor blades.

All in all, Siemens Wind Power is relying on modularization and reduced complexity to reduce costs. For instance, its new three-megawatt and six-megawatt turbines forego the usual combination of a gearbox and asynchronous generator. Instead, they use a directly driven synchronous generator equipped with permanent magnets and a corresponding conversion-to-grid frequency. This gearless direct drive concept eliminates 50 percent of the components normally used in such systems and reduces the unit’s weight by 30 percent.

Wind turbines also include modules such as, for example, hydraulic and power electronics systems that can be used in other products as well. Many module components – such as the electric motors for aligning the turbines – can thus be installed in various types of wind turbines. This lowers procurement and warehousing costs.

Customers not only benefit from the lower capital expenditure required for every megawatt of installed capacity; they also save money on maintenance. “The gearless design increases turbine reliability and by dong so lowers maintenance costs during operation,” says Rabe. “This is important because repairing a damaged gearbox offshore costs almost as much as installing the original turbine.” Most of the wind power plants that Siemens sells in Europe already use direct drive technology, which Rabe expects to account for the lion’s share of the portfolio in just a few years.

By then, it’s likely that the basic design of the nacelles will also change. Today, these components are still assembled at three plants: Brande, Denmark; Hutchinson, Kansas; and Shanghai, China. After assembly, they are transported to construction sites. But in the future, engineers plan to divide these complex system into two modules – the generator in front and the tail end, which holds the power electronics and the actuator for the nacelle. The idea is that the two modules should remain separated until they arrive at the top of the wind turbine tower. This approach would make production much more flexible. “Such modularization would enable us to manufacture the tail end at other locations around the world,” says Rabe. “However, the complex generator module would continue to be manufactured at only a few locations by Siemens, in much the same way that automakers build engines at their own centralized plants but have modules such as vehicle cockpits delivered.”

The cost of transporting these so-called split nacelles to construction sites would also be significantly lower. After all, depending on the country in question, it can make a big difference whether nearly 80 tons of cargo is shipped as a single package or in two separate, lighter loads along narrow roads and across fragile bridges.

Siemens’ innovative approach will soon simplify the transport of the towers as well. Most towers still consist of large and heavy steel segments with a diameter of up to six meters. These have to be stacked and joined at the construction site.

However, since 2012, Siemens has been offering bolted steel shells for particularly tall towers. Instead of using three segments, each several meters tall, the tower comprises 14 to 18 steel shells that are bolted together. “The individual parts of the new bolted shell towers can be shipped in a standard size container,” says Ferlemann. “The segments are also cheaper to manufacture because we can produce them in high volumes fully automatically from steel strip. This technique makes the segments very easy to paint as well.”

Ferlemann believes the cost of building steel shell towers over 115 meters tall can be reduced to a level far below the costs associated with conventional tubular towers made of individually manufactured steel rings.

Modeled on the Auto Industry. Siemens Wind Power wants to simplify and standardize its entire product portfolio in this manner. More specifically, it would like to reduce what used to be 13 product lines to just four platforms. Customers would then be able to choose between two turbines with 2.3 or three megawatts and two larger units with four or six megawatts. Each of the four platforms would in turn consist of six modules: the rotor blades, the segment linking them to the generator, the generator itself, the tail end, the tower, and the electronics needed to generate the grid frequency. These modules would also be made up of sub-modules. If this can be accomplished, the company will have succeeded in transplanting the automotive industry’s platform strategy into the wind power sector.

“The idea is to help build up a wind power industry that can play a key role – despite ever-decreasing subsidies,” says Ferlemann. “In the process, we can also learn from the automotive industry what one should not do. Some automakers have transferred their development expertise to their suppliers and lost know-how in the process. We’re definitely not going to do that. Siemens will always be able to not only develop its nacelles, rotor blades, and other components itself, but also assess the quality of the components it procures.”

Christian Buck