SeaMade Offshore Wind Farm, North Sea, Belgium
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SeaMade Offshore Windfarm, North Sea

SeaMade offshore windfarm is a 487MW wind power project developed in the Belgian exclusive economic zone (EEZ) of the North Sea.

Project Type

Offshore windfarm


North Sea, Belgium



Start of Construction

September 2019


SeaMade offshore windfarm is a 487MW wind power project developed in the Belgian exclusive economic zone (EEZ) of the North Sea. It is the single largest windfarm in Belgium.

The windfarm is owned and operated by SeaMade, which is a consortium of Otary RS (70% stake), Electrabel Electrabel (17.5%), and Eneco Wind Belgium (12.5%). It integrates two wind sites known as Mermaid and Seastar.

The windfarm will supply renewable energy to 485,000 houses in Belgium and offset 500,000t of CO₂ emissions a year.

The project achieved financial closure in December 2018. The offshore construction began in September 2019 followed by the turbine installation in June 2020. The project reached the final stage of construction with the installation of the last turbine in November 2020.

SeaMade offshore windfarm location

The 235MW Mermaid site is located 54km off the coast of Belgium at a water depth of approximately 40m. The 252MW Seastar site is located 40km away from the shore at a depth of 38m.

The Mermaid site is located next to the Northwester II windfarm, which is under construction. The Seastar site is located between the existing windfarms Nobelwind and Northwind.

Situated 50km away from the project, the Otary logistical hub in the port of Ostend supports the operations and maintenance of the windfarm.

Turbine details

The windfarm features 58 SG 8.0-167DD 8.4MW wind turbines from Siemens Gamesa Renewable Energy. The Mermaid site features 28 turbines while the remaining 30 were installed at the Seastar site.

"The windfarm will supply renewable energy to 485,000 houses in Belgium and offset 500,000t of CO₂ emissions a year."

Each turbine has a rotor diameter of 167m, hub height of 109m, blade tip height of 193m, and swept area of 21,900m².

The turbines have been installed on monopile foundations using DEME’s DP2 offshore installation vessel Apollo. The foundations were installed with a transition piece to house wind turbine generators (WTGs).

Power transmission from SeaMade offshore windfarm

Inter-array cables laid in looped string formation connect the WTGs to two substations. Each substation is linked to the grid through high-voltage XLPE 800mm² aluminium submarine cables rated at up to 245kV.

The export cables have a diameter of 247mm and weigh approximately 96.4kg per metre.

The offshore substations increase the voltage from 33kV to 220kV before feeding the modular offshore grid (MOG) operated by Elia Systems.


The SeaMade offshore windfarm was estimated to cost €1.3bn ($1.4bn). The European Investment Bank (EIB) provided a credit line of €250m ($282m) through the European Fund for Strategic Investments.

The project was funded by a syndicate of lenders, consisting of EIB, Danish export credit agency EKF, Santander, Société Générale, Siemens Bank, Bank of China, MUFG, Belfius, KfW IPEX, BNP Paribas, ASN Bank, ING, Commerzbank, Rabobank, SMTB, and Triodos.

Contractors involved in SeaMade offshore windfarm development

Siemens Gamesa Renewable Energy was awarded a contract to supply wind turbines for the project in December 2018. The contract also includes a 17-year service agreement.

Tideway-Hellenic Cables consortium received a $50m turnkey contract to deliver and install submarine export cables for the offshore windfarm in December 2018. Hellenic Cables was responsible for the production of the cables, while the installation will be performed by Tideway.

Dredging International was contracted to engineer, construct and install the turbine foundations and inter-array cables. ENGIE Fabricom, Tractebel, Smulders, and Geosea was responsible for the engineering, procurement, construction and installation (EPCI), as well as commissioning of the substations.

DEME undertook the EPCI of the turbines, foundations, inter-array, and export cables, along with the installation of two offshore substations.

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