Following the established targets for EU’s conversion to green energy, the international energy company Iberdrola is in the forefront, when it comes to development of offshore wind energy. One of the larger projects undertaken by Iberdrola is the offshore wind farm ‘Wikinger’, which is located in the German part of the Baltic Sea. At this location, an offshore wind farm is to be constructed of 350 MW produced by close to 70 wind turbines.
Complex and challenging conditions
In cooperation with Iberdrola, Geo has surveyed the seabed at the planned wind farm area, to 70 meters depth below seabed. The extensive survey programme has mapped an area with a complex geology. The large amount of collected soil samples and extracted data and information from the area have contributed to an optimisation of the design of the wind turbine foundations. Ultimately leading to cost savings in project economy, which again can lower the total cost of energy production.
Geo has carried out site investigations for more than 50 offshore wind farms.
Did you know that in just one day, Geo is able to map the geological layers of the soil down to 15 metres below the seabed for an 8-km2 area, using geophysics?
Did you know that experts initially feared that offshore wind farms would have a negative influence on the marine wild life, but that studies have ruled this out? Studies at e.g. Horns Reef Offshore Wind Farm, in Denmark, have shown a positive development in the diversity and biomass concerning both animal- and plant life, because the foundations for the turbines have created new artificial habitats and reefs.
In 1 day, Geo can drill and map the geological soil layers down to 70 m below the seabed, where the sediments can be up to 70 million years old. The sediment strength is of great importance for the foundation design.
Geo’s CPT seabed rig, GeoScope, is used for seabed investigations. During seabed investigations, GeoScope pushes a 36 mm cone into the seabed with a force equivalent to the weight of four elephants.
Geo has performed geotechnical site investigations and engineering consultancy for offshore wind farms since the first offshore project in 1990. Since then, Geo has been involved in more than 50 offshore wind projects in Northern Europe.
The survey methods developed by Geo take the lead in several ways. In cooperation with Iberdrola, Geo managed to introduce a unique drilling method to the Wikinger project, which made it possible to drill and select core samples of a very high quality adopting a method, which is normally only used onshore. Our ability to extract high quality cores and in situ data combined with an extensive laboratory programme, made Geo capable of conveying detailed information of the seabed’s geology and geotechnical characteristics to Iberdrola. Today the results from Geo’s offshore investigation is integrated into Iberdrola’s design process in order to optimise each wind turbine foundation.
Pedro Barbosa, Senior Geotechnical Engineer, Iberdrola describes Geo's participation in the project:
"Geo has fulfilled all contractual and technical obligations in another significant milestone for the Wikinger Offshore Wind Farm project".