Simultaneous construction and demolition of wind turbines create uniqueness

Along the E411, between Aische-en-Refail and exit 11 in Perwez, eight wind turbines will be dismantled and replaced by seven turbines that are higher and more powerful. This cooperation project between Eneco and Engie started in 2017 and was approved by the Walloon Region at the end of 2020. Five wind turbines were dismantled during the month of July. The three others will be dismantled in the coming days. The new wind turbines will be delivered in August.

Higher and more powerful

Thanks to this project, the current production can be tripled. Today, the eight wind turbines produce around 25,000 MWh per year, and with this new wind farm, they will be able to produce more than 70,000 MWh per year. The new wind turbines have new technologies, and are therefore more powerful. The towers are also up to about 30 m higher and the blades longer, so they can capture more wind and thus make more electricity. But this also requires more space between the turbines to avoid disturbance.

Recycle

The demolished wind turbines are still working perfectly. Three of them will serve as spare parts: the steel of the towers will be recycled along with the generator and other parts to be used in other projects. The five others will be completely rebuilt at other sites in Europe.

The distances between the wind turbines are no longer the same, so the new wind turbines have to be rebuilt on a different location. As a result, the foundations of the current wind turbines will be demolished and those locations will be restored to their original state, so that they can be used for agriculture.

"The pieces of concrete from the foundation are currently being removed and sent to a recycling centre, where they will be broken into pieces and used for the foundation of new roads, or remade into concrete," says Romuald Servaye, Project Manager at Eneco. "In autumn, these foundation pits will be covered and we will pull out the cables so they don't stay in the ground. The hole is then filled with earth from other groundworks, and the top layer is covered with fertile soil for agriculture."

Unique project

The project is unique, because the demolition of the old farm and the construction of a new one, have to be monitored simultaneously. The wind turbines must also continue to run as long as possible during the demolition works.

In addition, one of the wind turbines is financed by a cooperative between the municipality and local residents. That is why the project is also being looked at closely by, among others, mayor, Jordan Godfriaux and alderwoman for energy and environment, Véronique De Brouwer: "We are seizing the opportunity with this green project to produce green energy in our municipality. Almost 20,000 people can use this energy, which is certainly the double of our population."

Bats and birds

What is also interesting in this repowering story is that we can use the expertise of the old wind farm to take measurements and conduct biological studies on the existing fauna and flora. Two important measures were taken. Michaël Lavry, project manager wind turbines at Engie explains: "We know that bats tend to come out when the weather conditions are favourable for them, that means when it's not raining and it's not too hot. That is why we have provided a clamping system, in which the wind turbines are switched off to prevent a collision with the bats."

"A second measure was to carry out an environmental survey. We have identified a whole list of bird species that have returned to the region, despite the wind turbines. The Walloon Government has also asked us to take a whole series of environmental measures in terms of agriculture. For example, in winter we continue to feed the birds that return to the area within a 3 km radius. One hectare per wind turbine is used for this purpose. ", Lavry concludes.

The end of the work is foreseen at the end of this year or early next year. This depends on the weather.