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2012 Offshore Wind and Ecology Congress

October 11 & 12

Learn the latest on ecological effects of offshore wind farms!

  • Get the latest scientific knowledge on ecological effects of the Offshore Wind farm Egmond aan Zee
  • Meet and interact with international scientific experts, offshore wind industry, government, ngo's and agencies
  • Learn about effects on fish, birds, marine mammals and benthos

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Presence of bats confirmed in Dutch offshore wind farms

For the first time, firm evidence of the presence of bats has been found in the two offshore wind farms...

Ruige dwergvleermuis - René Janssen-4533 (3) lees meer >>

Research shows: first offshore wind farm in the Netherlands has positive impact on marine life

Amsterdam – October 11, 2012. A five-year scientific study has revealed the first offshore wind farm near Egmond aan Zee...

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Ruige dwergvleermuis - René Janssen-4533 (3)

For the first time, firm evidence of the presence of bats has been found in the two offshore wind farms on the Dutch Continental Shelf in the North Sea: Offshore Wind Farm Egmond aan Zee (OWEZ) and Princess Amalia Wind Farm (PAWP).

The species identified are the Nathusius’ pipistrelle (Pipistrellus nathusii) (see photo, © René Janssen) and the common noctule (Nyctalus noctula). Both species are known to cover long distances during migration, so these observations could refer to migrants . However, they could also be local populations flying back and forth from the mainland to forage. There are no indications of the presence of bat roosts in the wind farms. A follow-up study has already been started to gather information on how these bats are using the offshore wind farms.

The pilot study was carried out in autumn 2012 by the Fieldwork Company and IMARES Wageningen UR, in association with both wind farms. The study was prompted by Swedish research confirming the presence of bats in an offshore wind farm in the Baltic Sea. In addition, the presence of bats had already been noted on the Dutch Continental Shelf: on drilling rigs and ships, and observers regularly see them flying from the sea into coastal locations.

Ultrasonic sound recorders

Between late August and October 2012 ultrasonic sound recorders were used to prove that bats are present in Dutch offshore wind farms. These recorders register the sonar that bats use to navigate and forage during flight. Most species transmit a species- specific signal.

The equipment confirmed the presence of bats in both offshore wind farms. A total of 189 call sequences was recorded in Offshore Wind Farm Egmond aan Zee (29 Aug-20 Oct) and 25 in Princess Amalia Wind Farm (4-23 Sept). Of these sequences, 98% consisted Nathusius’ pipistrelle species and 2% common noctule. Most of the bat activity occurred early September.

Future research

This study shows that bats occur in Dutch offshore wind farms. Very little is known about their migration routes across the North Sea or their use of offshore wind farms as foraging area. As bats are a protected species, further research is necessary in order to account for the presence of bats at sea in the future. A follow-up study is the first step.

Amsterdam – October 11, 2012. A five-year scientific study has revealed the first offshore wind farm near Egmond aan Zee in the Netherlands has positively impacted life in and around the sea, and has had hardly any adverse effects.

The wind farm was constructed in 2006 by NoordzeeWind – a joint venture between Shell and Nuon – and has been fully operational since 2007. It is situated between 10 and 18 km off the Dutch coast and spans an area of 27 km². The wind farm provides electricity for over 100,000 households each year. In the late 1990s, the Ministry of Economic Affairs – now referred to as EL&I – decided to further investigate the potential of wind energy at sea and invest in the offshore array. They also ensured the project received a monitoring and evaluation programme, which required NoordzeeWind to scientifically research the impact of the wind farm on its environment.

 Five years of scientific research

IMARES, NIOZ and Bureau Waardenburg are the foremost research institutes in the Netherlands. NoordzeeWind asked them to research the impact of the wind farm on life in and around the sea. Five years of intensive scientific research followed. Four categories of animals were investigated: fish, birds, marine mammals and benthos. The Directorate -General for Public Works and Water Management also evaluated the research results. The most important conclusion was that the wind farm had mainly positive effects on life in and around the sea. The conclusions of the study will be presented at the Wind and Ecology congress in the Westergasfabriek in Amsterdam today and tomorrow.

 Future offshore wind farms

The results of this study are of huge importance for future wind farms that have yet to be developed. Naturally, no direct inferences can be drawn regarding the results of this study and other future wind farms, but the results do seem to point to this type of wind farm having a positive effect on life in and around the sea. The NoordzeeWind study is currently one of the top five studies of its kind worldwide, especially in terms of the extent and intensity of the research programme.

Research Results


This study not only investigated the general presence of fish in and around the farm, but also focused on the behaviour of two specific fish types: cod and sole. It appears cod has a tendency to stay within the realms of the farm, as higher concentrations of cod have been observed around the pillars of the wind turbines. This is probably due to the absence of fisheries in this area and the copious amount of food sources near the pillars. Fishing in the wind farm, or within a 500 metre radius of the border of the farm, is forbidden for safety reasons. The results of this study reveal no impact on the behaviour of sole. For the purposes of this study, tiny, innovative transmitters were implanted into the fish, which then communicated with receivers on the ocean floor.


Approximately five million birds fly within the vicinity of the wind farm each year. The NoordzeeWind study has shown most of these birds choose to avoid the farm, and fly over or around it. Birds that do enter the farm, know how to avoid the wind turbines, meaning only a tiny percentage – approximately 0.01% – are actually hit by the blades of the wind turbines. Researchers studying the birds used radar technology to map their migration. Surprisingly, the wind farm proved to be ideal for the Great Cormorant. Cormorants need to dry their feathers after fishing, which can be easily done at the wind farm. They pick a spot on one of the wind-turbine platforms and spread their wings, which they do in large numbers.

Marine mammals

Two types of marine mammal were investigated in the study: the seal and the harbour porpoise. Researchers were unable to observe any effects of the wind farm on seal behaviour. This is mainly due to the great distances seals travel. Seals can be observed throughout the North Sea including the wind farm. Hence the impact of such a farm, covering only 27 km2, is not discernable. Porpoise populations were measured in the wind farms using underwater microphones. The results revealed higher porpoise numbers in the farm than outside of it. This is possibly due to food sources available within the farm, or the peacefulness of the farm in what is otherwise a relatively busy area.


Research has revealed no effect up to now on benthos in the sandy areas between the wind turbine pillars. This may be due to the fact that young shellfish only mature once every five to ten years, something that hasn’t occurred in the last couple of years. However, other species have been found on the pillars and on the stones surrounding the pillars, which has led to increased local biodiversity.  

The results of the NoordzeeWind study are open to all and can be accessed via:

End of press release

If you have any further questions, please contact NoordzeeWind,

Natalie Kool, +31 (0)6 20 60 30 35 or

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