To assess the feasibility of an offshore wind project a number of site investigations are required. Producing a package of high quality site surveys helps reduce risk and ensure optimal design once the development stage begins. A range of Dutch offshore wind experts - companies and research organisations - have been involved in producing the site surveys for offshore wind farms in the Netherlands.
Overall, about 10 specific site investigations/studies/surveys are required (not including additional environmental impact assessment These centre around three core areas:
Soil conditions; and
Wind and water conditions.
Specifically, for Dutch offshore wind projects the following site investigations should be conducted:
Archaeological desk study - available geological, archaeological, and historical sources are studied, and information is gathered on seabed disturbances induced by human activities in the past to provide insight into any archaeological aspects that may have an impact on the development.
UXO Risk Assessment - providing initial insight into the risk of encountering unexploded ordnances (UXOs ).
Geological Desk Study - the starting point for several other studies, including more in-depth geophysical and geotechnical site investigations.
Geophysical Site Investigation - designed to improve the bathymetrical, morphological, and geological understanding of the area being investigated. The results are then used for planning a geotechnical campaign. The geological interpretation from the geophysical survey is integrated with the results of the geotechnical assessment of the geophysical survey results campaign. This produces a ground model for the wind farm site. The ground model will serve as the base for the design and installation of support structures and bases.
Archaeological Assessment of Geophysical Results - following on from initial work on the archaeological desk study, a subsequent archaeological assessment of the geophysical survey results is conducted. This further investigates the presence of archaeological remains at the site.
Geotechnical Site Investigation (Geotechnical Campaign) – meant to validate the geological model resulting from the geophysical investigation and to confirm the soil engineering properties at the site. Developers need this to progress with their geotechnical foundation designs and other general design and installation requirements for the wind farm, as well as those relating to cable installation.
Morphodynamical desk study (Morphology Study) - comprising two main elements. The first part addresses the (autonomous) seabed dynamics of the site. The second part, on scour and scour mitigation, provides general considerations on how to deal with scour development and scour mitigation. This takes into account the morphodynamics of the area and a range of potential types of foundations. General considerations for cable routing in a morphodynamic environment are also provided.
Metocean Campaign - here Wind LiDAR Buoys are deployed. These are equipped with an integrated system of instruments to measure wind, waves, currents, water levels, air pressure, and air temperature simultaneously.
Wind Resource Assessment - results are used as input for wind farm modelling, yield assessments, and business case calculations for the offshore wind farm. The study consists of an elaborated wind resource assessment using on-site metocean campaign data and off-site met mast data.
Metocean Desk Study - this provides information on the meteorological and oceanographic conditions of a site. This then serves as input for the design, installation, and maintenance of wind turbines, inter array cables, substations, and support structures, for companies submitting bids to develop projects.
The figure in the sidebar shows how the various studies relate to each other and their role in final wind farm design optimisation.
Once completed, quality certification of the site surveys and final data package is crucial. Read more here.
The Dutch Approach
The Netherlands Enterprise Agency (RVO.nl) commissions experts to conduct the site surveys for planned Dutch offshore wind farms and these are then subject to rigorous quality certification. The final comprehensive package of site data is then made available to potential developers to use to optimise their wind farm designs.
With expertise in each field of study required, as well as skill in bringing individual elements together as one strong package to help optimise design and reduce risk, the Netherlands can help replicate that success elsewhere to make wind and water work cost-effectively for others.
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