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A breath of fresh air for generating power


Taller, more lightweight, and made entirely of steel: Innovative TetraFlex® makes it possible to build the wind turbines of the future – out of steel. This will boost the efficiency of modern wind turbines.

Flying high (from left): Stefan Mayer, Dr. Lothar Patberg, Klaus Kottkamp, Jia-Uei Chan, and Dr. Yu Sun are ensuring greater wind turbine capacity with TetraFlex®.

Photo: thyssenkrupp/Rainer Kaysers

Wind energy is the ideal renewable energy – it does not use up any existing resources, and its availability is virtually unlimited. Since it does not release any pollutants, it does not pose any lasting threat to the environment. However, wind turbines can stand to be improved. Wind turbines currently in place are between 70 and 90 meters tall, on average. thyssenkrupp Steel has now developed a steel design called TetraFlex®, which enables the construction of wind turbines over 150 meters tall. Scaling the tower, rotor, and turbine allows for a significantly higher energy yield to be realized.

Steel construction that boosts energy yields

New steel design for wind turbines
New steel design for wind turbines: The base made of spiral welded tubes enables the construction of taller wind turbines. The higher the tower, the larger the rotors that can be used. This in turn increases the wind farm’s capacity.

Graphic: thyssenkrupp

This new design reduces conventional wind turbine design to a reduced-weight lattice structure. The design now consists of spiral welded tubes. This allows turbines to be constructed entirely from steel. Three pylons with a diameter of approximately 1.5 meters each constitute the load-bearing elements. In the center of the structure, a pylon approximately 2.5 meters in diameter enables maintenance access to the gondola. “This delicate construction makes the tower around 20 percent lighter and therefore less expensive than previous structures,” says Dr. Lothar Patberg, Head of Innovation at thyssenkrupp Steel.

Another advantage is that the tower can be created in individual segments and easily transported, independently of its final overall height. “The structure is designed in such a way that as much of it as possible can be pre-manufactured in assemblies,” says Stefan Mayer, who has overseen the development of TetraFlex® in the Innovation department from the outset. “At the construction site, you just need to screw the segments together.” The steel structure is also fully recyclable, in case dismantling is required.

First turbine in China

Chinese steel manufacturer Ansteel has served as the ideal partner for constructing the prototype. Together with this state-owned company, thyssenkrupp Steel has been running the joint venture Tagal for 15 years; this supplies hot-dip galvanizing systems to the Chinese automotive industry. At its Ba Yuquan location, Ansteel also generates electricity using its own wind turbines. “When they were planning a new expansion and learned about our TetraFlex® concept, they were immediately interested,” says Klaus Kottkamp, Application Consultant at thyssenkrupp and Project Manager for the prototype’s construction. “That was really serendipitous, since we’d been working together with them for years, and mutual trust was already in place. At their site, we can produce the segments, carry out the expansion, and then also provide the proof of concept.”

More power through wind power

China is not only the world leader in generating wind power, but also in expanding capacities for generating energy. The nation also wants to increase its production by 25 gigawatts each year. “As a result, over the next few years, China will install around 12,000 new wind turbines per year,” says Dr. Yu Sun, Head of Regional Business Development. In order to improve cost-efficiency, the market demands structures that use as little material as possible. At the same time, the towers need to be higher yet easy to transport. “The higher you go, the greater the wind speeds,” says Sun. “Moreover, higher up, wind power is more stable, which allows more electricity to be continuously generated.”

Ansteel plans to exchange one of the 70-meter towers at its facilities with a 150-meter TetraFlex® model. Kottkamp says, “Building this TetraFlex® prototype enables us to make direct comparisons with existing systems so that we can gain valuable findings about the energy output this technology yields.” In addition to providing data on efficiency, the prototype will also provide data on manufacturing, expansion, and maintenance for the new turbines.

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