The large-scale implementation of wind energy is hampered to a large extent by the unknown effects that wind turbines may have on the environment [6,9]. The collision of birds with turbines and the distortion of the migration routes are in that respect points of great concern. In environmental impact studies, estimates are made of the number of birds killed trough collisions or from exhaustion [1,3,4,7,8]. After the wind farm has been taken in operation, again investigations have to be carried out to verify if the estimates were right. To overcome especially the aspects that deal with colliding birds, ECN has initiated the project "WT-Bird , A low cost solution for detecting bird collisions".
The most commonly used techniques for counting bird collisions in an onshore wind farm are: manual search for corpses in the vicinity of the wind turbines, or by using radar. Both methods have in common that they are labour intensive, and thus expensive and time consuming. Usually the investigations end up with very few figures and large uncertainties. Offshore, these methods are hardly feasible. Corpses cannot be searched for, and radar still remains expensive. Moreover, investigations with radar in fact aim at distortion of migration routes more than on bird collisions.
The project "WT-Bird , A low cost solution for detecting bird collision" focused on developing a reliable and cheaper method for counting bird collisions in order to obtain more insight in the actual size of the problem, especially in offshore applications for which no alternative is available. Finally, this should lead to the situation that the deciding on placing wind turbines or not, can be taken on a more rational basis underpinned with actual facts and figures.
Objectives and Scope of Work
The objective of the project has been formulated at the time as "developing and demonstrating a system that determines a bird collision against a wind turbine and with which it is possible to determine the bird species". The system had to meet among others the following specifications:
- the system should be low cost in order to be competitive with manual counting methods;
- analysis of recorded data by e.g. ornithologist should not be labour intensive, meaning that only actual collisions should be recorded and no false data should be stored;
- the system should be able to operate under all weather and visibility conditions;
- the system should operate in offshore wind farms for long periods in a reliable manner and data should be accessible remotely.
During the definition phase of the project it was already recognised the above mentioned objective and specifications were very ambitious. To limit the scope of work some boundary conditions were defined already:
- microphones will be used for determining the impact and triggering sound and image recordings;
- low cost video cameras or web cams will be used for recognition of bird species.