Light pollution management on turbines
As more and more wind turbines are installed across Europe, keeping them out-of-sight of the local populations becomes an ever more difficult issue to address
Public acceptance of wind turbines has improved over recent years as the demand for greener energy sources has grown. The consequence of this is that many new wind parks are close to, or adjacent to, the local population. This may have some benefits for direct energy transmission to the end-user, but one environmental consequence is that the turbines have a pronounced visual effect on these populations. Combine this with the current technical trend for larger, taller turbines and these new turbines can been seen for many kilometres.
This visual impact effect is exaggerated at night, when the aviation warning lights become very apparent – as they are designed to be! This light pollution can be mitigated and local objections reduced at the planning stage, by use of a simple light management strategy.
There are several possible ways of providing this, including the use of ground based radar systems (high initial capital investment and on-going operational costs), plane transponder beacons (every plane needs to have one) or the use of visibility sensors. The lowest cost and simplest solution is to install visibility sensors on some of the turbines.
Many national aviation safety authorities are now accepting the use of visibility sensors to control the brightness (light output) of these aviation warning lights depending upon the local weather conditions.
By installing visibility sensors at the top of the nacelles, the real-time visibility (clarity of the air) is measured and so the lights’ brightness adjusted. For example, on a very clear day (or night) with visibility exceeding 10km, the lights’ brightness can be reduced to just 10% of its total output (typically 200cd’s). As the visibility drops (due to fog or rain) down to between 5km and 10km, the lights’ brightness is set to 30% output (600cd’s). Then if the visibility falls below 5km, the lights are switched to 100% output (2000cd’s).
Combine this measurement with networked, intelligent lighting controllers at the wind park and all of the turbines can be adjusted in unison, giving fast and effective lighting control.
In this way, the light pollution affecting the local population is greatly reduced on clear nights, whilst maintaining aviation safety as the weather conditions deteriorate. In addition, there is only a small increase in installed cost when compared to the other possible solutions (radar or transponders).