7  General Conclusions


The following conclusions and recommendations concerning future RTD-activities in most cases imply the construction of offshore farms, as monitoring programs and Before-After-Impact-Studies carried out at specific sites often represent the only possible way to achieve exact knowledge or at least an improved understanding of the impacts from offshore wind energy, particularly on the environment.


Furthermore, the offshore wind farms already constructed or planned may yield important information concerning issues like social acceptance and conflicts of interest if research projects dealing with these issues are carried out.


Therefore the recommendations below (Section 7.2) should not be regarded as barriers for the future development of offshore wind energy on the contrary, it is necessary that offshore construction projects are carried out, and in many cases it is necessary that some large-scale projects are carried out in order to achieve more information and knowledge regarding especially environmental issues.


These projects must however be subjects of intensive national and EU-funded research in order to reach conclusions about the impacts from offshore wind energy in relation to environmental questions, social acceptance and conflicts of interest: It is highly recommended that the present uncertainties and knowledge gaps are replaced by knowledge and certainty before real large-scale development of offshore wind energy is initiated.


7.1   Identification of problem areas


Potential negative environmental impacts:


  collisions with turbine

  turbines acting as barriers for migrating birds

  ousting of feeding/breeding areas due to

o   noise emission from turbines in operation and vessels during construction, maintenance and dismantling

o   movements of blades

o   serious changes in food chain, e.g. due to new sediment structure and unnatural reef effect

o    accidents (collisions with e.g. oil tanker not only causing ousting of birds due to oil spill, but also killing birds)


  loss of habitat due to

o   noise emissions

o   movements of blades

o   food chain changes

o   electromagnetic fields and vibrations, e.g. affecting the sonar system

o   accidents


  impacts on fish and fish larvae from sedimentation/turbidity, underwater noise, vibrations and electromagnetic fields

  effects from unnatural reef

  effects of accidents

Fauna and Seabed

  changes in sediment structure

  direct loss from foundation and cable footprints

  impact on biotope from foundations/hard substrates and electromagnetic fields

  disturbance/destruction of benthos due to accidents with ships/aircrafts


  impact on coastline due to current/sediment changes arising from cables

  impact on coastline due to accidents

Visual impact

  man-made obstacles in an otherwise structureless landscape

Noise impact

  increased blade tip speed and the ability of sound to propagate more efficiently on sea surface may lead to noise impacts

  impact on birds, sea mammals and fish from underwater noise


Conflicts of interest:

  collision risk with ships (including maintenance vessels), helicopters and low-flying aircrafts

  disturbance of radar and radio signals


Social Acceptance

  reduced acceptance due to unsolved environmental impact questions, lack of public influence on project (e.g. farm layout) and lack of public financial involvement in/ownership of offshore farms



  insecure/insufficient support mechanisms will block future large-scale development of offshore wind energy


7.2   Recommendations for RTD programmes


In general:

  It will be very important to collect information from different studies in order to cover the whole area, as different narrow site specific studies are carried out at the different projects: Baseline and impact studies from individual projects are to be disseminated and jointly appraised (also suggested in [xxxvii]). Conclusions from local projects should be translated and all relevant existing material placed on a publicly accessible web site.


Environmental impacts:


  As studies regarding the impact of offshore wind farms on birds and general studies on migration patterns are sparse, and as the effects depend on many different parameters, more knowledge is needed, both as general studies concerning bird migration and as site-specific studies: Ecological monitoring programmes/ Before-After-Impact-Studies are highly desirable in order to judge the effect on birds

  Define IBA/SPA borders and proximity to offshore farms

  Define flight paths

  Investigate how to minimize impacts from different farm and turbine layout (incl. marking requirements)


  More studies are needed to evaluate the effect from noise and magnetic fields, and the visual impact on mammals. Before-After-Impact-Studies, including seismic surveys and monitoring of underwater noise levels, and generic studies on noise reception of sea mammals are called for.


  As the effect of noise, vibrations (e.g. from placement of monopiles) and magnetic fields on fish is relatively unknown, studies and surveys must be carried out before, during and after construction: Site-specific and species-specific monitoring studies are necessary in order to investigate the effect of offshore wind farms on fish, e.g. investigate if foundations may indeed serve as natural reefs, as indicated from previous studies (e.g. Vindeby), the consequences hereof, and investigate the consequences on fish population/fishing possibilities when fishing (with net) is restricted within and in the vicinity of the wind farm



  The quality and quantity of possible impacts on seabed and benthos is not well known, calling for surveys of specific project sites, both as part of the EIA and as generic studies. How will the foundations/hard substrates and cable footprints/electromagnetic fields influence base-line biotope? Investigations should seek to enhance habitat, e.g. by use of appropriate foundation design.

Visual impact

  Research of computer simulation possibilities to test different farm layout seen from different angels, levels and at different weather conditions in order to make visualisations comparable to real-life conditions.

  Clearer definitions of marking requirements.

Conflicts of interest:

  Risk collision studies and additional information on damage mechanisms are called for in order to investigate the issue of marine and air traffic safety and offshore wind farms more closely.

  Radar and radio disturbance: for the development of large scale offshore wind farms it will be important that this subject is more closely investigated the conclusions from ongoing UK and Swedish studies may contribute with valuable information


Social Acceptance

  Studies of the effects of different ownership models and local ownership of offshore wind farms in relation to social acceptance




7.3   General recommendations for offshore wind projects


Fish, birds and other groups:

  Identification and avoidance of sensitive areas

  Avoidance of site works during sensitive time periods


  Layout design to accommodate flight paths, where these are defined.

Sea mammals:

  Minimisation of noise levels during construction, operation and dismantling


  Minimise effect of structures and cabling on stocks

Seabed, Benthos:

  Minimize sedimentations and turbidity

Hydrography, currents and water quality:

  Use of appropriate foundation design

Avoid use of pollutant chemicals when foundation, tower and turbine are protected against marine environment


  Early assessment taking account of distance from shore, marking lights and nature of viewpoints

Well-balanced marking lights taking into account safety issues (most important) and visual impact on man and animal 


  Ongoing PR work to counter poor publicity

  Maintain good standards of noise emission despite increases in turbine size and tip speed

Social conflicts:

Promotion of openness and local involvement

Risk management:

Develop risk management methods and emergency procedures in order to reduce risks of ship collision and to minimize consequences of collisions

1. Introduction
2. Environmental Impact
3. Conflicts of Interest
4. Social Acceptance
5. National Policies
6. Ongoing Research Projects
7. General Conclusions
8. Selected References
9. Appendix