05 April 2022

From mid-2022, wind turbines can be built significantly closer to so-called omnidirectional radio range beacons. This is the conclusion reached by scientists within the WERAN and WERAN plus research projects. The federal government is now implementing the recommendations.

Omnidirectional radio range beacons are used in air traffic control - there are around 50 such systems in Germany. These navigation systems send out radio signals that aircraft use to orient themselves. A turbine protection zone of 15 kilometres previously applied, in which building permit applications for new wind turbines had to be reviewed - this was to ensure that radio signals were not deflected and scattered by the wind turbines. However, this large radius also means a considerable area for which there was no planning certainty until now.

The findings from the research conducted under the leadership of the Physikalisch-Technische Bundesanstalt (PTB) now provide the necessary certainty for a move away from this practice. One of the results developed by the scientists in the WERAN and WERAN plus projects is a precise prediction method for predicting the effect of various obstacles on radio signals. The data obtained suggest that the test distance to wind turbines can be greatly reduced. Flight safety continues to be guaranteed.

Distance can be reduced to half

The German Federal Ministry for Economic Affairs and Climate Action (BMWK) has now agreed on a comprehensive package of measures with the Federal Ministry for Digital and Transport (BMDV), which takes up these research results and reduces the prescribed plant protection area from 15 kilometres to a general radius of 7 to 6 kilometres. The measure is to be implemented by mid-2022, the two ministries announced in their press release published today. Additional potential for onshore wind energy use can also be developed in the vicinity of weather radars. The additional areas therefore create a combined potential for 5 gigawatts of additional wind energy capacity in the short term, and currently blocked construction projects can be completed. "This is an important push for the expansion of onshore wind power", says Federal Minister for Economic Affairs Dr Robert Habeck, summing up the benefits of the results. "We are opening up more areas for the expansion of onshore wind through modern and smart rules. This is more important today than ever before. We have to put all our efforts into the expansion of renewables in order to free ourselves from the clutches of Russian imports as quickly as possible."

Years of investigations enable precise forecasts

Within the two research projects WERAN and WERAN plus funded by the BMWK, the collaborative partners systematically examined and validated the interaction of wind turbines and omnidirectional radio range beacons since 2013. One focal area, for example, was to record the signals in the airspace with suitable on-site measurement technology. The simulation of radio signals and their interactions was another key topic. There was good correlation between on-site measurements and simulations, which increased confidence in the results.

Most recently, the scientists developed a forecast procedure that allows them to precisely predict the interaction of the omnidirectional radio range beacons with new wind turbines. Other so-called interferers, such as buildings, trees, high-voltage lines or existing wind turbines can also be identified and their interference potential determined. The collaborative partners use this data to create a clutter map: a map into which the team can insert new construction projects, such as wind turbines, and interpret the interaction of all the constituents. "Thanks to the knowledge gained from the two projects, it is now possible to describe the effect of obstacles on the signals of omnidirectional radio range beacons in space much more precisely", explains Director and Professor Dr Thorsten Schrader from PTB. He adds that the safety of flight operations would also be increased because all obstacles would now be taken into account by the clutter map. For him, it has always been important to show that the expansion of wind energy in the vicinity of omnidirectional radio range beacons is possible without impacting flight safety. (mb)

Octocopter, equipped with measuring electronics for on-site investigations
© PTB

Wind power
Effect of wind farms on radar and navigation systems

New measurement methods provide information on the interactions between wind turbines and radar or air traffic navigation systems.

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