TNO made a study of whether or not wind turbines form a danger for shipping. The study showed that chances of an accident should not increase due to the presence of wind turbines. However the navigation routes will be even busier than they are now, since ships will have to avoid the parks. In that case, there is a greater chance of collision between ships in these routes. In addition, a ship out of control has more chance of colliding into a turbine.
Environmental lobby groups are in favour of offshore wind parks, but feel that care must be taken in choosing where they come to stand so that sea life is left undisturbed as much as possible and ships cannot readily collide with them. Fishermen are afraid that the turbines will be at the expense of their fishing grounds. The Coastal Union would prefer having floating wind parks built, further away from the coast, to prevent polluting the horizon.

The actual consequences for nature will only be apparent after a period of time once the wind turbines are working. However, the situation before the placement was charted on a large scale, so that the distribution of benthic animals, fish, marine mammals and birds is known prior to placement. Now that one park is in operation, the study will be repeated in the near future. Since no fishing is allowed in the vicinity of the parks, fish will probably find the parks a safe refuge.
When constructing offshore wind parks, it is possible that damage occurs to the hearing organs of marine mammals. Porpoises can become victims of extremely loud noise when ramming in the poles for the turbine foundation. These poles are hammered 30 meters into the sea bottom, which means using heavy material to accomplish the task. Although the contractor uses pingers to chase the porpoises away, it has not been proven whether it is sufficient. There is little experience with these kinds of effects. Studies of hearing organs in washed up porpoises will show whether or not the animals are victims of such activities.
It is still unknown what the effects of wind turbines will be on birds flying above the North Sea. One option is that they will be chopped to pieces by the vanes. The score in Denmark (where offshore wind parks have been standing since 2002) a year after the opening in of one of the parks, is the following: the birds stay a long distance away from the turbines during the day, but fly closer at night due to non-visibility. A number of birds fly into the vanes, but it is assumed that it is not a dramatic amount. Another consequence is that migrating birds must fly around them, costing extra energy that could lead to a less successful nest. As of yet, no studies have been done in this field.
In the Netherlands, a test arrangement to register the number of birds that fly into a turbine has been placed. Four microphones register the noise of the turbine and a video camera starts filming when a strange noise is heard. The images are sent to a computer on land, where ornithologists determine which bird it is.

The most important technical problems in building and maintaining a wind energy park at sea are the forces which affect the turbines, the immense corrosion from salt water, the increased chance of being struck by lightning and the maintenance. Because a park at sea is far away, maintenance must be kept to a minimum.

The government had the Dutch Central Plan Bureau execute a cost-benefit analysis for the general public. From their study, it seemed reasonable to assume that 6000 megawatts in wind energy at sea could be achieved by 2020, but the costs in all cases will be greater than the profits. In other words, building wind parks cost billions of euros in subsidies but yields little for the economy and climate. Wind energy is cheaper than a scenario where the parks would be built in phases and according to strict international climate policy. If only a minimum of CO₂ is allowed to be discharge, then the use of oil would decrease making wind energy a better alternative and balancing out the social costs and benefits.