The Gemini Wind Park was built out at sea, surrounded by maritime flora and fauna. How do you manage that as carefully as possible, during and after construction? Luuk Folkerts manages the project in terms of permits and environmental monitoring. The ambition: to minimise the impact, now and later.


Starting with the choice of the location and the permit process for the wind park, the environmental impact has played an inmportant role in the planning. Everything has been done in close consultation with the government, Luuk Folkerts explains. ‘We’ve shown that we understand it, how we prevented as much damage as possible and that we monitor carefully. It’s also special that our project contributes to expanding our knowledge of nature and the environment.’
Gemini has executed a research program which is aimed at monitoring possible ecological effects on marine life. This program started a few years before construction of the wind park and continues during construction and a number of years into operations. This monitoring program is specifically aimed at determining distributions and behavioural responses of birds, fish, seals and harbour porpoises in the area of the wind park site.

Respect for Mother Nature

Knowing how marine life could possibly be influenced by construction activities starts by installing the right equipment. At various locations and at varying intervals, specialised C-pods (hydrophones) were installed that can pick up the sounds from passing mammals.

A read-out from the C-pods used by

Gemini at the end of June 2015, when

the monopiles were being constructed.

The dots indicate the presence of

harbour porpoises, seals and dolphins.



Part of the strategy was to test as much as possible onshore and in that way avoid offshore construction problems. The main contractor Van Oord built a mock-up for the interface from the monopile to the transition piece in Antwerp harbour. It was possible to test many different elements in this way, such as the bolts connecting the two pieces, but also the cable pull-in, for example. The mock-up was kept in place for three months, allowing the Van Oord engineers to come up with the optimum solution for the offshore wind park.

The onshore mock-up proves its worth



The foundations are protected against metal corrosion by a system of Impressed Current Cathodic Protection (ICCP). The system consists of anodes connected to a power source that is suitable for a large structure such as foundations. The advantages of this system are, amongst other things, that the level of protection can be adjusted and there is no waste metal that might cause pollution.


Protecting the foundations

In the circle, the system against

corrosion being tested in Antwerp, with the mock-up installation of the monopile and the transition piece.