Demand-controlled night marking (ADL) for new wind turbines

BNK: Put an end to pointless Flash

The Demand-driven or needs-based night marking, or BNK for short, ensures that the lights of wind turbines only flash when a flying object is actually nearby. The systems record the position and route of aircraft. While earlier ADLK systems were based on radar technology transponder-based recognition has now become Enforced. Here, flying objects emit signals that are emitted by the turbines be recognized.

The Transponder-based ADLS offers two variants:

Multilateration: Several receivers determine the position of an aircraft based on the Time differences in the reception of the signal. This method is particularly precise, but requires an elaborate infrastructure.

Single Receiver Approach: A single receiver estimates the position based on signal strength and direction. This variant is simpler and cheaper, but less so exactly.

Modernity BNK systems such as the light:guard system can use both approaches, depending on the Location. In densely populated regions, multilateration ensures a more precise detection and longer phases without flashing. In isolated locations a single receiver is often sufficient.

History of BNK in Germany

The legal obligation to equip ADLS was already established in 2019 in the Renewable Energy Sources Act (EEG). Originally, it was supposed to be 2020, but has been postponed several times – most recently to January 1, 2025. This was due to technical challenges, certification problems and pandemic-related bottlenecks. In the meantime, however, the providers and operators and many wind farms have already been able to activate their ADL.

ADLS for new installations

Some new wind turbines and new wind farms also have already have an active or at least installed BNK. It has to be that way, from the new year at the latest. New plants must be equipped with a active BNK, without exception. If this requirement is not met, face severe penalties: 10 euros per kilowatt per month installed capacity – for a 3.5 megawatt plant, this adds up to 35,000 euros. Operators and project developers must therefore plan for ADLS at an early stage.

Thanks to optimized processes, ADL systems can can now be installed more efficiently. Providers like Light:Guard cover large parts of Germany, so that the systems are often implemented within a few weeks.

Looking to the future

Whether BNK can already be considered a success, is still unclear, as it is important for a assessment of public acceptance is too early. First data show promising results: In areas with little air traffic, the wind turbines are almost completely dark.

Too the technology is attracting international interest. In Austria, BNK while it is already established in the Netherlands. In the coming years, demand-driven night marking worldwide – a win for residents and the night sky.