It seems like such a minute detail. Yet, time and time again, the mandatory high intensity obstruction lights on large wind turbines have brought prospective wind farm projects to a complete standstill.
Landowners and neighboring communities have objected to having their night sky ruined by the white and red flashes from wind farms. This is frustrating for wind farm developers, as high-yield projects have been delayed for extended periods of time or have even been cancelled altogether.
However, it is not hard to understand why landowners have protested against the high intensity lights. Honestly, most of us would prefer an undisturbed night sky. But what if there was a way to get both the green energy source and the beauty of a starry night?
Keeping the Lights Off
A solution to this “light” pollution problem has in recent years been introduced at wind farms in Europe and North America. Basically, the remedy is no more than a motion-sensing light switch. One that automatically activates the obstruction lights of the wind farm, when an aircraft is detected within a designated safety radius of the turbine. Once the airplane returns to a safe distance away from the turbine, the lights then automatically switch off.
Consequently, this radar-based light control system will keep the lights off up to 90 % of the time while still complying with the safety regulations.
In other words: there is significantly less disturbances in the night sky, wind farms can become less intrusive to neighboring landowners, and the “light” problem is no longer an issue.
Until now, agreements between landowners and wind farm developers have often entailed far-reaching compromises from either side of the table: either the surrounding communities have had to tolerate the presence of the wind farms in their landscape both night and day, or developers could be forced to reduce the number of turbines or redesign the layout of the farm altogether.
By introducing an automated light control system, wind farm developers are now able to vastly reduce the visual impact that aviation obstruction lights have on local communities and wildlife. This ability may ultimately be a decisive factor in helping stalled wind farm projects become a reality.
Boeing, Bat or Bald Eagle?
Needless to say, it takes a little bit more than your average household light switch to control the obstruction lights of hundreds of wind turbines.
The Obstruction Light Control System is based on the same advanced radar technology Terma uses for critical installations at e.g. airports, which can detect airborne objects ranging from the largest passenger jets to light aircrafts and even birds.
According to Henrik Bendix Nielsen from Terma, “The question is not, whether we can detect an object; the question is, can we tell the difference between a legitimate target (i.e. a plane) and a bat or bald eagle?”. Nielsen, however, suggests that this degree of precision might soon be a reality. Great ambitions and cutting-edge technology fit, as Terma is the company behind newly installed light control systems in both Germany, Denmark and the U.S.
The reason for the exceptional radar sensibility is simply that in order to deliver a stable and secure light control system, the radar must detect even the smallest aircraft in even the harshest weather condition.
With such a sensibility, telling the difference between birds and aircraft becomes more than a peculiar detail: it is a necessity to avoid erroneously turning on and off the lights all night long.
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Radar based solution that keep lights turned off at Wind Farm in Germany.
Cutting Costs by Sharing Systems
With the wind farms in Denmark, Germany and the U.S. paving the way, several other farms in Europe and North America have been approved for the automated Obstruction Light Control system.
The system can be implemented in both new wind farm projects and retrofitted into existing ones. The flexibility of the light control system even allows for several wind farms to share a single unit. A single aircraft detection radar could therefore work as the joint light switch and control the lights of two or more wind farms located near each other.
While this means that wind farm owners can share the cost of the radar and the ongoing maintenance, it does not mean that all lights turn on and off simultaneously.
“The OLC system is highly configurable. Let’s say you have a wind farm area that is 15 kilometers wide by 25 kilometers long. Why turn on the entire wind farm when a plane flies across the upper northeast corner? By separating the area into zones, we can enable the lights residing in just the zone that is being affected. This spares the majority of communities located within the wind farm area from seeing any lights at all,” explains Nielsen.
This technology is now well on its way in the US and has already been in use for several years in a number of European countries where Terma is spearheading the market. Here the results have been the same: Less annoyance for the surrounding communities, and, importantly, easier approval of new wind farms; thus, enabling developers to keep their deadlines and stick to their budget.