Conference programme

Back to the programme printer.gif Print



Wednesday, 18 November 2015
17:00 - 18:30 Cumulative impacts on birds
Environmental impacts & social acceptance  
Onshore      Offshore    


Room: Montmartre

In this session presentations on actual effects of onshore and offshore wind turbines on birds will be presented.

Learning objectives

  • New detection techniques on bird collisions
  • Cumulative impacts on different bird species
  • Mitigation techniques
Hans Verhoef ECN, The Netherlands
Co-authors:
Hans Verhoef (1) F Karen Krijgsveld (2) Ruben Fijn (2)
(1) ECN, Petten, The Netherlands (2) Bureau Waardenburg, Culemborg, The Netherlands

Share this presentation on:

Printer friendly version: printer.gif Print

Abstract

Measurements of bird collisions at the OWEZ offshore wind farm with the WT-Bird system

Introduction

The number of birds that collide with offshore wind turbines has only been estimated, based on collision risk modeling (CRM) and experience with onshore turbines. Almost no actual measurements of collision rates have been carried out. In recent years, several techniques have been developed to measure collisions. WT-Bird is a system that is applied in an offshore wind farm.

With this study , the use of acoustic/visual detection devices to measure collisions of birds with offshore wind turbines can be propelled forward. The results are among the first of its kind and can be used to calibrate collision rate models.


Approach

A WT-Bird detection device (developed and owned by ECN) has been installed at the Dutch Offshore Wind farm Egmond aan Zee (OWEZ). This WT-Bird device consists of two acoustic detectors per turbine blade, combined optionally with three cameras covering the entire rotor-swept area. Acoustic impacts are recorded, along with visual footage of the minutes prior to and during the impact, thus providing information on collisions and species involved. By combining the recorded collisions with measurements of bird flight intensities and avoidance behavior we are able to assess the results on collisions in the context of local fluxes and avoidance rates.

Main body of abstract

To date, the number of birds that collide with offshore wind turbines has only been estimated. Almost no actual measurements of collision rates have been carried out, due to the practical difficulties related to monitoring collisions offshore. As a result, actual offshore collision risks are unknown and estimates largely depend on data on avoidance behavior of birds around wind turbines, which are scarce and highly variable. In recent years, several techniques have been developed to measure actual collisions offshore.

To improve our insight in collision risks offshore, and to validate an automated detection method, we are measuring collision rates at one offshore wind turbine for two years. For this purpose, a WT-Bird detection device has been installed at the Dutch Offshore Wind farm Egmond aan Zee (OWEZ). We will combine the recorded collisions with measurements of bird flight intensities and avoidance behavior, in order to be able to assess the results on collisions in the context of local fluxes and avoidance rates.

Here we address the techniques currently available or in development in Europe and the USA and their status, and present the first results of ongoing measurements with WT-Bird. We present preliminary data on the number of collisions, diurnal distribution of collision events, and bird species involved. Bird fluxes at the time of events are presented as well as flight patterns at the site. Results are compared with estimates of bird collision rates as calculated for OWEZ based on CRM and avoidance rates.


Conclusion

With this study, the use of acoustic/visual detection devices to measure collisions of birds with offshore wind turbines can be propelled forward. The results are among the first of its kind and can be used to calibrate collision rate models and therefore we get a better insight in the actual number of bird collisions with offshore wind turbines.


Learning objectives
The learning objectives of this study are summarized as follows:
• Get insight in real number of bird collisions in offshore wind farms
• Input for calibrating collision rate models
• Operational experience with offshore application of bird collision system WT-Bird