Vulnerable marine environments can sustain wind farms

Major 100-200 MW wind farms can be established and operated without significant effects on the vulnerable marine environment. This is the conclusion of the first systematic research in the world looking at the effect of the wind farms on nature.

Major importance for future development
A group of international marine ecologists have monitored the programme at Horn’s Reef and Nysted in the Baltic during the period 1999-2006, and their assessment is that the results of Danish research will be decisive for the future development of global wind farms as new methods like the T-POS system have been used for measuring the supersonic activities of porpoises and special technology for recording birds colliding with wind turbines.

Part of the conditions for approving the two large wind farms was to carry out comprehensive monitoring to record the consequences for the fauna and vegetation of the seabed, fish, mammals and birds. Horn’s Reef and Nysted are situated in two different marine environments, so the results are to be considered representative for offshore as well as costal waters.

The monitoring programme was carried out in three phases according to the international BACI-method (Before-After-Control-Impact). During the period 1999-2001 the existing conditions were recorded to establish a reference. In 2002-2003 the environmental conditions during the construction were recorded, and till 2006 focus has been on the consequence of the operation of the wind turbines. The first phase was financed as a part of the mandatory VVM-evaluations, while the 84 million DKK programme for 2001-2006 was financed by the Danish consumers of electricity.

During the construction, consideration for mammals like seals and porpoise
was prioritized. Noise from hammering down piles and sheet piling might
harm such animals, so they were scared away in advance by acoustical alarms.
At Nysted special restrictions for access to the wind farm were established
as the farm was set up only some 2 km from a nature reserve and 4 km
from the Rødsand seals reserve.

 

New habitat for life on seabed
The two wind farms created a new environment consisting of wind turbine foundations and erosion protection on the sandy seabed, and these artificial reefs have created a habitat with more animal life than before. More mussels have turned up, and at Horn’s Reef the number of starfish has grown, and the artificial reefs have resulted in a new and more varied population of algae playing an important part in the food chain of the sea.

During the construction of the wind farms the marine mammals disappeared as expected, but at Horn’s Reef the seals soon returned in their usual number, whereas at Nysted it took a -little longer.

The more diversified fauna on the seabed gives reason to expect a positive influence on the amount of fish in the area, but such a theory takes time to prove. Neither has it been possible to see any direct effect from the electromagnetic radiation from the marine cables at Nysted.

Generally, birds are good at avoiding the wind turbines, so the rate of collision has been as small as .2 per mille. The birds seem to be able to detect the turrets and blades, so the turbines present no danger to the marine birds even if some of them have moved to other areas for food. Experts, however, feel that future research should focus on the accumulated effect of setting up several wind farms in the same area.

In addition to the environmental conditions the programme has been looking into the attitude of the local population towards wind farms. Here the trend shows a generally positive attitude. At Nysted the population mostly agreed to pay a little extra for electricity to finance moving wind farms further away from the coast in order to eliminate their visual pollution.

 

For more information, see Danish Offshore Wind- ens netboghandel.dk and www.ens <http://www.ens/> . dk/sw42149.asp.