The 1.5GW Hollandse Kust Zuid (HKZ) offshore wind farm project is located in an area of the North Sea divided into four parcels, 18km off the coast of the Netherlands. It is the first non-subsidised wind farm project in the country.
The wind farm is jointly owned by Vattenfall, a Swedish energy company, BASF, a chemicals company, and Allianz, an insurance company, with 25.3%, 49.5% and 25.2% interests respectively.
Recommended White Papers
Recommended Buyers Guides
The Netherlands government awarded the tender for the construction and operation of the first two parcels of the wind farm (Zone Sites I and II) to Chinook CV, a subsidiary of Vattenfall, in March 2018. The initial preparatory works for the parcels began in March 2019. The company won the tender for the remaining two parcels (Zone Sites III and IV) in July 2019.
The final investment decision on the wind farm was taken by Vattenfall in June 2020. Construction began in July 2021.
The wind farm was inaugurated in September 2023 and is expected to be fully operational by 2024. The electricity generated by the farm is sufficient to power 1.5 million households in the Netherlands.
The project is in line with the Dutch government’s target to produce 3.5GW of new offshore wind energy by the end of 2023.
Hollandse Kust Zuid wind farm location
The HKZ wind farm sites are located in the 235.8km² Hollandse Kust (zuid) Wind Farm Zone (HKZWFZ).
The HKZWFZ is situated west of the Netherlands, offshore the Zuid-Holland (South Holland) and Noord-Holland (North Holland) provinces, in water depths between 18m and 27m.
It contains the operational Luchterduinen wind farm on the northeastern side and is enclosed by the coastline and main shipping routes of IJmuiden and Rotterdam. The northern side of the HKZWFZ is bordered by a sand extraction area, with anchorage areas towards the northern and southern parts of the zone.
The site’s favourable conditions include suitable seabed and water depth, ideal weather conditions and proximity to the port of Ijmuiden, the maintenance hub for the HKZ wind farm.
Details of the Hollandse Kust Zuid wind farm
Zone Sites I and II of the HKZ wind farm, each with a capacity of 350MW, cover an area of 115km². Zone sites III and IV span 110km² with a total capacity of 750MW.
139 wind turbine monopile foundations have been erected and 315km of 66kV inner array grid cables laid, using heavy lift, cable-laying and support vessels.
The monopile foundations of the turbines weigh between 735t (62m) and 955t (75m) and are installed at water depths between 17m and 28m.
The wind farm zone contains several active, inactive, existing and planned cables and pipelines. The maintenance and operational activities of the wind farm are controlled from the port of Ijmuiden.
The government has approved the installation of 252 wind turbines with a maximum height of 251m above sea level and a minimum capacity of 6MW at Hollandse Kust Zuid.
Wind turbine details
The HKZ wind farm is equipped with 139 units of the new SG 10.0-193 DD offshore wind turbine, featuring IntegralBlade manufacturing and direct-drive technologies.
The wind turbines have a rated power of 10MW and can generate 11MW of power. The length of the rotor blades is 94m, while the diameter of the three-blade rotor of the wind turbine is 200m with 29,300m² of swept area. The wind turbine is estimated to improve annual energy production by 30%.
Direct-drive wind turbines are lightweight and smaller with a lesser number of wear-prone components. A permanent magnet generator, which requires no excitation power, is used in the turbine to improve efficiency. All these design elements reduce the installation, operation and maintenance costs of the turbines.
The installation of the last turbine was completed in June 2023.
Power supply details
The HKZ wind farm contains two offshore transformer platforms, HKZ Alpha and HKZ Beta, each with AC connections of 700MW.
Each platform contains two 220kV AC export cables. Electricity generated from the turbines is transferred to the platforms through 66kV infield cables. The electricity is stepped up to 220kV at the platforms and transported through export cables to the onshore 380kV Maasvlakte high-voltage substation.
Four 550m-long pipeline sections were laid by controlled horizontal directional drilling under the seawall south of the Maasgeul channel. The pipelines safely connect both platforms to the Maasvlakte substation with cables.
The electricity moves to the south ring of the TenneT-operated Randstad 380kV line and then to the national high-voltage network for distribution. The HKZ Alpha high-voltage substation was installed using Sleipnir, a semi-submersible crane vessel.
Funding
Vattenfall agreed to sell a 49.5% stake in the offshore wind farm to BASF for a consideration of €300m ($353m) in June 2021.
BASF’s total commitment for the project amounts to €1.6bn ($1.88bn) including the funding for the wind farm’s construction. The deal is part of BASF’s aim to reduce its greenhouse gas emissions by 25% by 2030 and achieve net zero emissions by 2050.
PPA supporting Hollandse Kust Zuid wind farm
In March 2021, Air Liquide, a French industrial gas producer, entered a 15-year power purchase agreement (PPA) to off-take 100GWh of clean energy generated by the wind farm to power its factories in the Netherlands.
The electricity generated by the project is acquired by BASF, as per its ownership share, through a long-term PPA to support the production of chemicals at its sites across Europe, in particular at the Antwerp Verbund facility in Belgium, the biggest plant in the country.
Contractors involved in Hollandse Kust Zuid wind farm project
TenneT signed a contract with Vattenfall to provide offshore grid connection for the third and fourth sites of the wind farm in April 2020. The agreement for the first two parcels was signed in 2019.
Vattenfall selected Seaway 7 for the transportation and installation of 76 monopile foundations and infield cables for sites I and II in April 2019. Subsea 7 was contracted for the transportation and installation of monopile foundations and cables in April 2020.
Sif Group was contracted to supply the monopile foundations, while Siemens Gamesa is responsible for providing the wind turbines. Swire Blue Ocean was selected to install the turbines using Pacific Osprey, the flagship wind farm installation vessel.
The Van Oord-Hellenic Cables consortium received a contract from TenneT for the delivery and installation of sea and land cables for the Alpha platform. LMR Drilling was subcontracted for horizontal directional drilling for the installation of the cables and platform.
Petrofac won a contract for offshore grid connections. The company subcontracted Heerema Marine Contractors to transport and install the HKZ Alpha high-voltage alternating current platform.
Prysmian Powerlink and Twentsche Kabelfabriek are responsible for the manufacture and supply of the inter-array cable systems for connecting the turbines to the two offshore high-voltage stations.
Windcat Workboats was contracted to provide a hydrogen-powered boat for maintenance activities. Drydocks World is building the HKZ platforms Alpha and Beta.
