Fire-Free: First Wind Farm in Germany Dark at Night

The fact that the conversion of electricity generation to renewable energies must take place now and for good finds wide support in the population. But acceptance often abates quite quickly with people having growing wind power plants in their own neighborhoods. An argument repeatedly brought forward by opponents is the continuous flashing of the turbines' light installations in the dark. A change in German law, however, should make this a problem of the past.

In general, all structures that might jeopardize flight safety must be identified according to an international treaty under the Convention on International Civil Aviation, also known as the Chicago Convention. Every country having acceded to the agreement has a certain margin to define the precise rules on this subject. In Germany, all structures that have a total height of more than 100 meters must be equipped with night markers. This also includes wind turbines, which must be equipped with a hazard fire or a blast fire (in conjunction with an obstacle fire).

In other countries, there are a number of stricter directives. In the US, all turbines along the periphery of a wind farm have to be marked at a height of 200 feet (61 meters). In the UK, a night mark is required from a height of 300 feet (91.4m).

As a result of Germany's high population density of 226 inhabitants per square kilometer many people feel disturbed by the nightly flashing. Also in rather sparsely populated North Frisia (in Schleswig-Holstein, the most northern part of Germany) residents complain about flashing lights. No wonder as there are more than 1,000 turbines higher than 100 meters and therefore especially marked.

However, a change in law at the end of 2015 has opened possibilities for alternatives. Since then, it has been possible to install an appropriate marking on the plants meaning that the night fire is switched off until an aircraft actually approaches the location of the turbine from a range of more than four kilometers. After detecting the aircraft with the aid of a sensor the system switches on the obstacle fires. When the sky is clear again, it switches off automatically.

On Monday last the first wind farm in Langenhorn-Bordelum was equipped with the technology. ENERTRAG Systemtechnik, who installed the Airspex system, had initially installed it at six of the turbines. Now 17 further plants were equipped.

Wind farm Neudorf by night (Photo: Windradfreak, CC BY-SA 3.0 de)

To symbolically hit the off-button, Schleswig-Holstein's energy minister Robert Habeck had arrived at the scene. "It disturbs many people when wind turbines flash at night and never get dark. The technique to finish this is now available. We have therefore created incentives for installation in the federal state and are also driving the issue forward to the government in Berlin.”

In 2016, the Ministry of Energy, Agriculture, Environment and Rural Areas of Schleswig-Holstein established a financial incentive system in order to accelerate the introduction of demand-oriented lighting systems. The retrofit of the system in Langenhorn cost around € 28,000 per turbine according to NDR (German broadcaster). In addition to the wind farm operators, pilots must also familiarize with the new system, since when switched on, it lights up briefly three times before flashing in the known rhythm. In case of failure the entire system is switched on and behaves as usual.

According to Habeck the interest in the lighting system is great, but: "...This will still take a while. These are all licensing procedures, which can not be done overnight. But I am sure that in the next two to three years we will see considerable darkness returning to Schleswig-Holstein."

At the moment, another German wind farm is being equipped with the new Airspex system in the Uckermark region (Brandenburg, East Germany).

The business potential is enormous: in Germany alone, more than 27,000 wind turbines are installed – not to mention the rest of the world.