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A breath of fresh air for generating power

Wind turbines at the forefront of technical progress

Tetraflex Project Team Wind Power Steel

The climate goals that the international community must achieve are ambitious. But how can we satisfy our energy requirements if we continue to reduce the amount of fossil fuels used in energy production in order to lower CO2 emissions? One of thyssenkrupp Steel’s project teams has the answer: TetraFlex®. These innovative wind turbine towers have literally skyrocketed renewable energy production to new heights.

The new steel construction holds up the hub of the wind turbines at a height of over 140 meters. This is more than 50 meters higher im comparison to conventional wind turbines, which makes an enormous difference due to the wind blowing steadier and stronger at these altitudes. According to Klaus Kottkamp – Application Consultant for thyssenkrupp Steel and the driving force behind the development of the TetraFlex® prototype – with the current and proven wind turbine technology, approximately 20 percent more power can be produced depending on the location and topography. The result: depending on the wind profile and wind turbines, these towers can produce up to 20 percent more energy per year. “At the same time, we significantly reduce building costs with this type of construction, which can be decisive in determining whether future projects of this type are realized.”

Wind Turbines Put to the Test

“What we know so far is that we are extremely competitive in terms of time and costs,” explains Dr. Siear Qaimi, who is head of the TetraFlex® project in the Regional Business Development team at thyssenkrupp Steel. What was previously based on theoretical calculations will now be substantiated with figures on the basis of the prototype, which will be built in China. He also wants to find new answers to his clients’ most pressing questions: what are the worries and problems with a project of this type and what can be improved? Many new ideas have already stemmed from the current project and the collaboration with experts in the wind power industry, reports Dr. Qaimi. “These developments, which have great cost-saving potential, are already or soon will be patent-pending.” And the team has been thinking ahead for quite some time now: in addition to the current solution for onshore wind turbines, there are also offshore applications.

Tower Height Meets Demand

While the team is validating the theoretical data with real results and further optimizing the wind turbines, they are also driving the market opportunities for TetraFlex® by continuing to set up joint ventures. Dr. Yu Sun, Head of Regional Business Development, is happy to report that “the negotiations are nearly complete.” Klaus Kottkamp agrees: “that which belongs together has come together here.” What do they mean by this? “We have the ideas and the technology; in China there is the demand. This provides a profitable application for the project.” The plan is to build a wind farm on the site of the former iron mine of our Chinese project partner Ansteel. This year, they are looking to create the conditions for several new wind turbines.

Wind Power: Strong Partner Network

The joint venture relies on a very extensive local network when it comes to implementing the plans. “The supply chain is already there,” says Klaus Kottkamp. “In this sense, we do not need to reinvent anything since we already have all the materials, expertise, and technology available to us.” Experienced specialists – selected on the basis of many years of trust-based cooperation – are ready to get started. This means that production can be ramped up as required, which is the major advantage of TetraFlex®’s design concept. As Dr. Qaimi explains, “we believe in using a modular design. It makes transportation and construction easier and the tower can be erected within three weeks,” he promises.

Steel is Perfectly Suited for Wind Power

Dr. Sun believes that this could be an important success factor for TetraFlex®: “The market for wind power is currently developing very dynamically, especially in Asia. In terms of wind energy, China alone is planning to install 25 GW per year. Our concept allows us to overcome the existing barriers to market entry very elegantly.” When asked whether entering into the wind energy sector is not also associated with a high risk, he replies: “we are sticking to what we’re best at: demonstrating the potential of steel and then finding ways to implement these solutions.” He is certain that the TetraFlex® project is being closely monitored in the industry. Good ideas for renewable energies are not only in high demand in China but also globally. “Maybe one day there will even be a TetraFlex® in Duisburg,” he says.

TetraFlex®’s Design Creates Benefits:

  • A light but very stable structure: The steel structure weighs just 500 to 600 metric tons, compared to the over 1,500 metric tons of a hybrid tower made of steel and concrete
  • Faster construction: The modular design makes transportation to the site easier
  • Material and employee network: By using standard materials, everything is onsite, which means there are no long delivery routes
  • Comparatively low CO2 footprint: Producing the alternative material – concrete – has an even greater impact on the environment
  • 100% recyclable: If necessary, the components can be reused, which is not the case with concrete

A breath of fresh air for generating power

Tetraflex project team
Siear Qaimi and Klaus Kottkamp are ensuring greater wind turbine capacity with TetraFlex®. © thyssenkrupp/Rainer Kaysers

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.

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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thyssenkrupp Steel Europe AG

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47166 Duisburg, Germany

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