Energy is a prerequisite to function in today's society. In order to meet current and future energy demands, growth in sustainable energy is essential. The Netherlands has accepted the European set goal for sustainable energy, thereby committing to the agreement that in 2020 14% of the Dutch energy consumption originates from sustainable resources.
The objective for wind energy at sea was arranged in the Energy agreement for sustainable energy (September 2013). As stated in the draft of the North Sea Policy Paper 2016-2021; in 2023, 4.450 megawatts (MW) of wind energy output at sea must be operational. Which is 3.450 MW more than the energy delivered by present wind farms and wind farms still under construction. Wind energy at sea therewith makes a large contribution in achieving the target of 16% of sustainable energy which the Dutch cabinet has set for 2023. Enormous investments and policy-efforts are needed to accomplish this enormous task.
Many uncertainties still exist concerning the effects of wind farms on the North Sea’s ecosystem. European legislation demands a safety-margin when the consequences of certain processes are unknown; the precautionary approach. The lack of knowledge about the ecological effects also affects cost-efficiency in realizing the set goals for wind at sea. Therefore the Ministry of Economic Affairs and the Ministry of Infrastructure and the Environment have instructed to investigate important environmental questions concerning the construction and exploitation of wind farms. In 2011 the results of the so-called “Shortlist-study Ecological Monitoring Wind at Sea” were published and presented at a symposium. These results led to an adaptation of the methodology in the assessment framework for ecological effects of wind farms at sea.
The next step in increasing knowledge on the ecological effects of wind farms at sea was to follow up on the above mentioned Shortlist-study. The Follow-up Implementation Masterplan (VUM) Ecological Monitoring Wind at Sea was started in 2011 and recently finished. It was carried out by a consortium led by Imares and TNO. The investigations were substantively guided by the Ministry of Economic Affairs, Rijkswaterstaat and the Directorate-General for Spatial Development and Water Affairs of the Ministry of Infrastructure and the Environment.
The research for VUM consisted of 9 sub studies:
- A sound model for piling at sea;
- Risk assessment tool for cumulative effects of underwater sound (SORIANT);
- The effects of offshore piling sound on the hearing of Harbor Seals;
- The effect of piling sound on the survival of fish larvae;
- The effects of offshore piling driving sounds on the hearing and behavior of harbor purpoises:
- Hearing thresholds of a harbor porpoise (Phocoena phocoena) for playbacks of multiple pile driving strike sounds,
- Hearing frequencies of a harbor porpoise (Phocoena phocoena) temporarily affected by played back offshore pile driving sounds,
- Effect of exposure duration to pile driving sounds on temporary hearing threshold shift in harbor porpoises,
- Hearing thresholds of a harbor porpoise (Phocoena phocoena) for narrow-band sweeps;
- Swimming speeds of marine mammals in the North Sea;
- Bat migration at sea;
- Modelling the number of seabird collisions with offshore wind turbines;
- The effect of wind farms on seabirds.
In addition, a workshop on international harmonization and collaboration was organized.
This booklet contains a brief abstract of all the VUM-studies. The complete reports are available at the Informatiehui Marien (www.informatiehuismarien.nl) and the Noordzeeloket (www.noordzeeloket.nl). The findings of the VUM-studies were presented at a symposium at Naturalis in Leiden at 8 September 2015.
The results of the VUM-studies have been and will be applied in the decision-making process for offshore wind farms. Furthermore, the results will be used for the ‘Ecology and Cumulation Framework’ which was announced in the draft of the North Sea Policy Paper 2016-2021, published in April 2015. The framework is intended to clarify how cumulative ecological effects need to be investigated, it’s meant to be applied in future decision-making concerning wind energy at sea.
Besides the above-mentioned VUM-studies, many other studies are implemented in this area. For example the monitoring programs of existing farms and farms that are under construction. A lot of research is also being done abroad. The Ministry of Infrastructure and the Environment have taken the initiative in a few processes to stimulate international collaboration and knowledge exchange. In the above mentioned Ecology and Cumulation Framework, as well as during the completion of the VUM-studies, several new knowledge gaps were determined. Therefore, on short term additional research will be initiated.