SeaMade Offshore Windfarm, North Sea

SeaMade offshore windfarm is being developed in the Belgian Exclusive Economic Zone (EEZ) of the North Sea.

Project Type
Offshore windfarm
North Sea, Belgium
Start of Construction
Expected Completion
Estimated Investment
€1.3bn ($1.4bn)
SeaMade (Otary RS, Electrabel and Eneco Wind Belgium)

SeaMade offshore windfarm is being developed in the Belgian Exclusive Economic Zone (EEZ) of the North Sea. The 487MW project will integrate two wind sites known as Mermaid and Seastar. It is the single largest windfarm being funded and built in Belgium.

The windfarm will be owned and operated by SeaMade, which is a consortium of Otary RS (70% stake), Electrabel Electrabel (17.5%), and Eneco Wind Belgium (12.5%).

The windfarm will supply renewable energy to 485,000 houses in Belgium and offset 500,000t of CO2 emissions a year. It will enable the nation to achieve a target of 13% renewable source of energy by 2020.

The project achieved financial closure in December 2018, while offshore construction is scheduled to begin in mid-2019 with the aim of completing in 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 will support the operations and maintenance of the windfarm.

Turbine details

The windfarm will feature 58 SG 8.0-167DD 8MW wind turbines from Siemens Gamesa Renewable Energy. The Mermaid site will feature 28 turbines, while the remaining 30 will be 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 will have a rotor diameter of 167m, hub height of 109m, blade tip height of 193m, and swept area of 21,900m².

The turbines will rest on monopile foundations, which will be installed with a transition piece to house wind turbine generators (WTGs).

Power transmission from SeaMade offshore windfarm

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

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

The offshore substations will step-up the voltage from 33kV to 220kV before feeding the modular offshore gird (MOG) operated by Elia Systems.


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

The project is 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 windfarm in December 2018. Hellenic Cables will be 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 will be responsible for the engineering, procurement, construction and installation (EPCI), as well as commissioning of the substations.

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