The Vesterhav Nord and Syd project involved the construction of the Vesterhav Nord and Vesterhav Syd offshore wind farms in the Danish waters of the North Sea.
Developed by Swedish energy company Vattenfall, the two wind farms have a combined capacity of 344MW.
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The project can generate 1.57TWh of green power a year, which is sufficient to meet the energy needs of 380,000 households in Denmark.
The permit to commence construction of the project was awarded by the national energy regulator Danish Energy Agency in December 2020.
The final investment decision on the project was made in December 2021. The offshore construction work of the two wind farms started in January 2023.
In January 2024, Vattenfall announced the completion of Vesterhav Syd, after all its wind turbines started generating power and were connected to the Danish power grid.
Vesterhav Nord also commenced full operation two months later in March after being fully connected to the Danish grid.
Project location
Vesterhav Nord is located between 5.5km and 8.4km off the West Jutland coast at Harboore. Vesterhav Syd is located between 4km and 10km off the coast of Ringkobing Fjord.
Vesterhav Nord and Syd make-up
The Vesterhav Nord and Vesterhav Syd wind farms have an installed capacity of 176MW and 168MW, respectively.
The project is powered by 41 Siemens Gamesa SG 8.0-167 DD turbines, 21 for Vesterhav Nord and 20 for Vesterhav Syd. Each DD turbine has a power generating capacity of 8.4MW.
The nacelle height of each turbine is 109m while the height of the wingtip can reach up to 193m. The rotor diameter of the turbines is 167m while the swept area of each turbine is 21,900m². The length of each blade is 81.4m.
The wind turbines were installed on monopile foundations, topped by transition pieces, at water depths of up to 20m. Weighing up to 260 tonnes, each transition piece helps to connect the wind turbine to the monopile foundation.
The turbines of Vesterhav Nord have been installed 710.5m away from each other while the distance between the turbines at the Vesterhav Syd wind farm is 685m.
Vesterhav Nord and Syd construction
Fabrication work on the 41 transition pieces (TPs) started in early 2022, with delivery of the last TP taking place in April 2023. Similarly, work on the foundations was also completed in the same month.
Preparation works for offshore installation started in January 2023, followed by the installation of the first monopile in February and the completion of the foundations in April.
Onshore cable installation was carried out in April followed by the commencement of offshore cable installation in July.
The turbine installation for Vesterhav Syd took place between July and September 2023. The first power from the wind farm was delivered two months later in November.
The turbine installation for Vesterhav Nord was carried out in late 2023 and the first power was produced in February 2024.
Grid connection for Vesterhav Nord and Syd
The power generated from the two offshore wind farms is transmitted onshore by 60kV cables.
The power from Vesterhav Nord is collected at an onshore substation, and the electricity is then transmitted to the high-voltage substation at Idomlund, where it feeds the Danish grid.
The grid connection for Vesterhav Syd involves an onshore collection point at Søndervig near the coast. The electricity is then transferred to a high-voltage substation at Stovtrup using a 150kV cable.
The electricity transmission network is operated by Energinet, the Danish national transmission system operator.
Contractors involved
Siemens Gamesa Renewable Energy was selected to supply its wind turbines for the Vesterhav Nord and Syd wind farms in November 2017.
Vattenfall engaged EEW Special Pipe Constructions in November 2021 to fabricate 41 monopiles for the Vesterhav project.
Bladt Industries was contracted to manufacture and supply 41 transition pieces for the wind farms. Vattenfall selected DEME to install foundations for the project, with the works carried out from the Port of Thyboron using the vessel ‘Innovation’.
Jan De Nul Group was chosen for the transportation and installation of the 41 turbines, using the Vole au vent jack-up installation vessel.
Hellenic Cables received a contract in August 2021 to design, manufacture, and supply 70km of 66kV XLPE insulated interarray cables for the Vesterhav project.
EDS HV Group was engaged for high-voltage network commissioning and safety management.
Ordtek was contracted to identify UXO targets for the wind farms.
Asso.subsea was contracted for the transportation, installation, and protection of 66kV export and interarray submarine cables.
Correll Group was selected by Asso.subsea for offshore pull-ins and termination and testing of turbine cables while Rohde Nielsen was selected to install a protective layer of armour rock on the turbine foundations.
TUV SUD was chosen to provide certification for the wind farms while Accura provided legal support to Vattenfall on regulatory and contractual matters.
Mercell was selected to support Vattenfall on the supply of onshore grid work for the wind farms.
Per Aarsleff was chosen to supply and install land-based cables and transformer stations. Prysmian’s Danish subsidiary was selected by Per Aarsleff to supply the onshore connection for the wind farms.
Orbicon prepared the 2020 environmental impact assessment report for the project.
Plaris Consultancies provided project management consultancy services to Vattenfall.
