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Offshore Wind Journal

Seabird collisions with offshore turbines fewer than previously predicted

Fri 20 Apr 2018 by David Foxwell

Seabird collisions with offshore turbines fewer than previously predicted
A two-year study suggests bird collisions with offshore wind turbines are less frequent that thought (photo: RSPB)

A newly-published Bird Collision Avoidance Study suggests that seabird movement is much less affected by offshore windfarms than was believed and that collisions with turbines occur less frequently than was thought.

The study from the Offshore Renewables Joint Industry Programme (ORJIP) claims to be the world’s most comprehensive investigation into seabird behaviour and collision risk around offshore windfarms.

It is the first of its kind employing a multi-sensor monitoring system, combining human observer-based tracking with a system that automatically recorded seabird movements, at a working offshore windfarm in the English Channel. Radars were also used to record data 24 hours a day for two years.

The multimillion pound, collaborative study was commissioned by 11 leading offshore wind developers, The Crown Estate, The Crown Estate Scotland and Marine Scotland, was supported with funding from the UK Government and was managed by The Carbon Trust. The project was developed and run with the support and advice from the UK and Northern Europe’s leading ornithologists and environmental advisors such as Natural England and Royal Society for the Protection of Birds.

During the two years of fieldwork a significant number of videos were recorded at a representative area of Vattenfall’s Thanet offshore windfarm, one of the largest in UK waters. This resulted in the analysis of over 600,000 videos, of which only 12,131 contained evidence of bird activity and only six collisions with turbines were observed. The analysis revealed that collision risk of seabirds was less than half of what would be expected based on current understanding. During the study seabirds were observed to exhibit avoidance behaviour and change their flight path to avoid the turbines.

To obtain planning consent for an offshore wind development the planning inspectorate needs to consider the risk of environmental impacts, as well as any mitigation measures proposed by a developer. The developer needs to provide evidence of how seabirds will behave within and around the farm. To quantify bird collision risk with turbines, collision risk models are used to estimate this impact. Although extensive studies have looked at migratory patterns and behaviour of seabirds around offshore windfarms, until now there was only limited evidence to substantiate their actual behaviour.

The conclusions from the research on collision risk will allow better-informed windfarm design and consent decisions just as the next generation of more powerful offshore turbines are being tested and manufactured. As a result, the research will support UK Government plans to rapidly and sustainably grow the offshore wind sector by 2030.

The research was designed to generate robust, empirical evidence on the levels of avoidance behaviour and collisions to improve collision risk models. This will provide greater certainty on the true impact of offshore windfarms on seabirds and the mitigation measures required.

Vattenfall UK country manager Piers Guy said “This pioneering study, hosted at Vattenfall’s Thanet offshore windfarm, is a significant step forward in our understanding of the way in which seabirds avoid offshore wind turbines, and comes at a crucial time as the next generation of wind turbines are designed and developed. The research will support UK Government plans to rapidly and sustainably grow the offshore wind sector by 2030.”

Scottish Government energy minister Paul Wheelhouse said “Scotland has tremendous potential for sustainable development of offshore wind and floating offshore wind sites and, to date, we have more than 4 GW of consented projects, while Crown Estate Scotland are looking at future leasing opportunities. This study therefore provides invaluable data for understanding the potential impact of offshore wind developments on seabirds as part of our efforts to develop this vital energy resource with due regard to the marine environment. The data yielded will therefore be of great help to inform our offshore wind consent and planning process and help achieve our objective of growing a sustainable offshore wind sector, whilst preserving Scotland’s much-loved wildlife.”

The methodology for analysing the results was also developed specifically for the project and is a key project output to be shared with the wider industry. Project data is publicly available via The Crown Estate’s data sharing platform the Marine Data Exchange.

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