EU Offshore Study: Average Wind Turbine Hits Only One Dozen Birds Per Year

 

A new industry-backed study aims to push back on claims that the offshore wind industry is a threat to migratory birds. The consultancy-performed study concludes that (at least in the EU) birds almost completely avoid wind turbines and that the risks of collisions are significantly lower than previously assumed.

The study commissioned by industry lobby group German Offshore Wind Energy Association (BWO) has now refuted assumptions that high migration intensity by birds in waters where offshore wind farms are being developed automatically lead to collisions. In its findings, the study contends that over 99.8 percent of migratory birds avoid wind turbines. In essence, it means that blanket shutdowns of turbines during periods of heavy bird migration is not a sensible approach.

Conducted by research and consulting firm BioConsult SH GmbH, the study sought to establish the risks of collisions between migratory birds and offshore wind farms in the North and the Baltic Sea, regions that are fast becoming hubs for offshore wind power.

With the study site being the Windtestfeld Nord wind farm near Husum, Germany, the researchers were able to analyze the movement patterns of over 4.2 million birds over a period of one and a half years. The wind farm spans approximately 150 hectares with five operating wind turbines of varying types and sizes being used for the study, where bird species like geese, ducks, gulls, waders and songbirds are common.

To understand the movements of the birds, camera systems were installed on two of the turbines and recorded all bird (and bat) passages through the rotor plane both during the day and at night. Nocturnal activity was captured using infrared cameras in combination with infrared emitters. To assess general migration intensity in the area, the team used a specialized bird radar that was operated continuously throughout the entire study period, and which was designed for real-time monitoring of bird movements.

BWO has described the combination of radar and the AI-based cameras as a methodological breakthrough that enabled unprecedented accuracy in recording bird flight movements in the rotor plane. In effect, this allowed the team to come to the conclusion that nocturnally migrating birds avoid collisions with wind farms and that the overall collision risk in relation to the total amount of birds passing a wind farm at night is very low.

This was based on the results of the fatality surveys, which indicated a relatively low number of collision victims of an estimated total of 99.7 fatalities of all bird species being recorded across the study period at the five monitored wind turbines. This corresponds to a mean of 12.9 collision fatalities per year and turbine.

“The new study shows that migratory birds avoid wind turbines. This confirms that the environmentally sound expansion of offshore wind energy works in harmony with these birds and not against them. With this research, we want to depoliticize the discussion, improve the data basis, and make decisions based on facts,” said Stefan Thimm, BWO Managing Director.

The study, which now provide a solid basis for the expansion of offshore wind energy, comes when Germany is pursuing growth in renewable energy. The country has set targets to increase offshore wind capacity to 30 GW by 2030, 40 GW by 2035 and 70 GW by 2045. By end of last year, a total of 1,639 turbines with a capacity of 9.2 GW were installed in the country.