Quantification and characterisation of Belgian offshore wind farm operational sound emission at low wind speeds

Offshore renewable energy installations contribute to the continuous underwater sound that has been identified as an environmental concern under the EU Marine Strategy Framework Directive. This study quantified, characterised and compared the continuous underwater sound emitted by steel jacket foundation and monopile Wind turbines during operation at low wind speed (0-12 m/s). The operational sound emitted by a monopile founded and a jacket founded wind farm in the BPNS showed a maximum increase of SPL of about 20 dB re 1 µPa. Spectral analysis showed that this increase occurs at frequencies below 3 kHz. Steel monopile foundations even when equipped with a less powerful generator, emitted significantly more underwater sound than jacket foundations. The addition of underwater sound is increasing with wind speed with a rate dependent of the type of foundation, with monopiles showing a stronger increase with wind speed than jacket foundations. Possible impacts on marine life like fish, marine mammals or invertebrates remain unclear mainly due to the lack of knowledge in disturbance or behavioural response levels for the species that could be found on these sites. Future challenges are to expand the study to higher wind speeds (study ongoing) and to quantify and qualify the additional sound pressure of a larger wind farm or a series of adjacent smaller wind farms (i.e. cumulative effects)

Assessment of the conservation value of the Vlakte van de Raan Site of Community Interest

Based on the best available knowledge, the current study analysed the habitats’ and species’ conservation value for the specific delineated Vlakte van de Raan Site of Community Interest (SCI) in the Belgian part of the North Sea (BPNS). The habitat types 1110 and 1170 and the species Phocoena phocoena and Alosa fallax were analysed for the 19km² Vlakte van de Raan SCI. These analyses are based on the criteria: representativeness, conservation status, recovery potential, surface area and conservation value. The Habitat type 1110 at the Vlakte van de Raan SCI turns out to be a mosaic of areas of poor and medium ecological value, interspersed with some elements of high ecological value (i.e. part of the Abra alba biotope). The combined surface area is negligible compared to the Vlaamse Banken SCI or the total surface of the BPNS, indicating a low conservation value. The ecological value of the Habitat type 1170 at the Vlakte van de Raan SCI scores very low, indicating no conservation value for this habitat type. For the harbour porpoise Phocoena phocoena, the Vlakte van de Raan area shows the lowest densities found in Belgian waters, leading to the conclusion that the ecological value of the Vlakte van de Raan SCI for harbour porpoise is to be considered negligible.Twait shad Alosa fallax is known to occur within the Vlakte van de Raan SCI (data from 1 beam trawl sample in the area). However, taking into account the different scientific criteria, the ecological value of the Vlakte van de Raan SCI for A. fallax is to be considered anecdotal and its conservation value as negligible. Any conservation measure within the Vlakte van de Raan SCI will be ineffective for this migrating species. In conclusion, based on different criteria, the scientific analysis shows very poor to no nature conservation value for the habitat types and species for which the site was initially proposed, leading to the conclusion that the Vlakte van de Raan SCI has no value as a special area for conservation

WinMon Activity Report 2013-2014

Belgium has allocated a 238 km² zone of the Belgian part of the North Sea to offshore renewable energy production, for example offshore wind farms. Prior to construction, a developer needs obtaining a domain concession and an environmental permit. The latter includes a number of terms and conditions to minimise or mitigate the environmental impact of the wind farm project. This also imposes a monitoring programme to assess the potential impacts on the marine environment. The environmental monitoring programme targets physical (hydro-geomorphology and underwater noise), biological (epifouling community on the hard substratum, macro and epibenthos of the soft substratum, fish, seabirds and marine mammals), as well as socio-economic (seascape perception and offshore renewables appreciation) aspects of the marine environment. The Operational Directorate Natural Environment (OD Nature) of the Royal Belgian Institute of Natural Sciences (RBINS) coordinates the monitoring programme. To cover all necessary scientific expertise OD Nature collaborates with several institutes: the Research Institute for Nature and Forest (INBO), the Institute for Agricultural and Fisheries Research (ILVO - Bio-Environmental research group), Ghent University (Marine Biology Research Group and INTEC), International Marine and Dredging Consultants (IMDC) and Grontmij Belgium NV. The Belgian offshore wind farm environmental monitoring programme started in 2005 with the t.i data collection at C-Power wind farm on the Thorntonbank, where the first wind turbines were installed in 2008. The monitoring programme is running continuously since 2008 (i.e. to) and now (July 2015) covers three wind farms (i.e. C-Power, Belwind and Northwind) with a total of 181 wind turbines. This report provides an overview of the monitoring activities that took place in the years 2013 and 2014. These cover the investigation of soft sediment benthos and fish, hard substrate benthos, seabirds and marine mammals. The activity overview distinguishes between basic and targeted monitoring, with basic monitoring focusing on the observation of the overall offshore wind farm impact and targeted monitoring aiming at the understanding of the ecological mechanisms behind a selection of observed impacts. For each activity, its objectives, methodologies used and data collected in 2013 and 2014 are presented. If further information on specific sections would be needed, do not hesitate getting in touch with the contact point as identified for each sectio