A superlative among wind farms

12 super-turbines for 90,000 households

Zuidwester onshore wind farm. Twelve wind turbines with a total generating capacity of 90 megawatts replace the 50 old turbines. Source: Klaas Eissens AV Produties

And then there were 12

Twelve super-turbines on the Dutch coast generate clean electricity for 90,000 households.

One of innogy’s largest onshore projects is currently taking shape right on the IJsselmeer: the Zuidwester wind farm, representing an investment volume of over €150 million. Along a one-kilometre stretch of the dyke, twelve of what are currently the world’s most powerful onshore wind turbines are about to go into operation. They replace 50 traditional wind turbines. Each of the super-turbines can generate as much electricity as all the units in the old wind farm put together.


Onshore wind farms. The driving force behind the energy transition

Wind power: it needs no fuel, it will not run out, it’s climate-friendly and is a driving force behind the energy transition. In the past twenty years or so, it has come out of the shadows to become one of the leading renewable energy technologies.

innogy is currently implementing a total of five onshore projects in Germany, the Netherlands and the UK.

Hans Bünting, COO Renewables at innogy SE. Source: RWE
Building new onshore wind farms is part of our core business. It’s how we actively work to drive forward the energy transition.
Hans Bünting, Chief Operating Officer Renewables (COO Renewables), innogy SE

innogy makes the best possible use of good locations and the latest technologies to integrate electricity generated using wind into the market as cost-effectively as possible.


More efficiency in the same space

The Zuidwester wind farm, for example, forms part of the Noordoostpolder project on the IJsselmeer, one of Europe’s most innovative wind power undertakings. A total of 86 onshore and offshore wind turbines are planned.

Repowering at Zuidwester – upgrading from old to new wind power technology – “makes technological progress something you can perceive directly,” says Bünting. “It enables us to make better use of our limited land resources, while contributing more toward achieving Holland’s goals for the expansion of renewables and the transformation of the energy market in Europe.”

The result of the upgrade is there to be seen. Whereas, plants with a generating capacity of 300 kilowatts were standard in the 1990s, top-of-the-range systems such as the new wind turbines at Zuidwester can now achieve 7,500 kilowatts (7.5 megawatts).


Building on the former sea floor

Work on dismantling the old facilities at Zuidwester began at the start of 2014. “This was followed by construction of the transformation station, relocating the power cables, and building the foundations and towers,” says Rick van Mensvoort, innogy building supervisor, explaining the building stages of this major project, which is taking shape on what was once the sea floor. The area where the dyke now stands was still under water 70 or so years ago, before being drained in 1942.


From the foundation to the blades

With a diameter of 26 metres, the foundations for the wind turbines are reminiscent of oversized doughnuts.

In addition to concrete posts up to 32 metres in length and weighing a total of over 20 tonnes, 1,400 cubic meters of concrete were poured to create the supporting structure. Due to the soft ground, each crane site was reinforced by around 2,400 supporting posts. Within the space of just half a year, 29,000 posts were installed into the ground.

Construction video of the Zuidwester wind farm. Constructing the foundations. Source: RWE
One of the world’s largest sets of onshore foundations is being constructed at the IJsselmeer, forming the base for the wind turbines that reach about 200 metres skywards. Source: RWE

Then comes the assembly of the wind turbine, which is comprised of the nacelle, generator, hub and rotor blades. The wind turbines are supplied by ENERCON, based in Aurich, Germany, which is behind what is currently the most powerful wind turbine, the E126. Star British architect Sir Norman Foster made a creative contribution to the transformation of the European energy market by drafting the design for the high-tech wind turbine.

Construction video of the Zuidwester wind farm. Sequence 2: Assembling the first turbine. Source: RWE
Assembling the first turbine at the Zuidwester onshore wind farm on the IJsselmeer. Source: RWE

The rotor blades are made up of two parts. The first half is connected to the hub at the ground level. Attaching the hub and rotor blades has to be done at a dizzying height. The parts are lifted into the right position using a crane. As if in slow motion, the arm carrying the 127-metre-long rotor blade moves toward the hub – this is precision work. The last step of the job involves screwing them both together. Success! But there is one more thing left to be done. The tips of the rotor blades are now gradually connected to the second half. The rotor diameter is now 127 metres. The wind turbine is finished and ready for operation.

The flagship project at Zuidwester is gradually taking form.


Rick van Mensvoort, innogy building supervisor at the Zuidwester wind farm. Source: RWE
All development work and the grid connection are complete and all towers have been erected. The first wind turbines are now going through trial runs. We want to commission the rest of the turbines in the next few months. So we’re right on schedule.
Rick van Mensvoort, innogy building supervisor

The Zuidwester onshore wind farm at a glance

Twelve of the world’s largest onshore wind turbines (7.5 MW) will replace 50 older systems.
90 megawatts of installed capacity right on the IJsselmeer.
Investment volume of over €150 million.

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