Nordergrunde offshore wind farm is an 111MW wind project developed approximately 15km to the north-east of the Wangerooge Island within the German shores of the North Sea.
Construction of the offshore wind farm began in May 2016 and the first Senvion 6.2M126 turbine was installed in August 2016. The transformer platform weighing roughly 2,000t was installed on 22 September 2017.
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The project was completed with the connection of the last 18 turbines to the grid in December 2017. The wind farm supplies electricity for more than 100,000 households.
WPD developed the project through its subsidiary OWP Nordergründe with an estimated investment of €410m ($455m approximately). The owners of the Nordergründe wind farm include John Laing Group (30%), WPD (30%), and Gothaer Leben Renewables (40%).
Nordergrunde offshore wind farm make-up
Nordergründe is the first German offshore wind project for which all major components were supplied and installed by local manufacturers.
The project is located in water depths of up to 10m and within a 12 nautical mile zone of the German North Sea.
Each wind turbine has a rotor diameter of 126m and a swept area of 12,469m². The cut-in and cut-out wind speeds of the turbine are 3.5m/s and 30m/s respectively. The maximum sound level of the turbine is 109db. The rotor blade is made of glass fibre-reinforced plastic (GFRP) and has a length of 61.5m.
Weighing approximately 370t, the turbine monopiles have a diameter of 5.5m and a maximum wall thickness of 60mm.
A fully automated fire protection system that includes active smoke and aerosol detectors is installed within the nacelle, switch cabinets, and transformer room.
Construction of the German offshore wind farm
Laying works for the 4km land cable began in the autumn of 2012 and the substation was expanded in 2013.
Roll-on-roll-off vessels were used to shift the nacelles to the site, while the turbine components were moved on the cargo pontoon directly using self-propelled modular transporters (SPMTs).
More than 10,000t of steel was used for manufacturing the turbine foundations.
The inter-array cables were installed by the cable-laying barge, NOSTAG10, which was specially designed for applications in shallow and near-shore waters in close proximity to the shore in water depths from 2.5m to 10m.
Transmission
Power generated at the Nordergründe offshore project is fed into the 220kV grid before transporting to the on-shore Inhausen substation. A 32km-long 155kV connection line, including 28km-long subsea cable and 4km-long on-shore cable, was laid.
Financing of Nordergrunde offshore wind farm
Debt funding for the project was provided by the European Investment Bank (EIB) and KfW IPEX Bank under an agreement concluded in June 2015. EIB funded €156m ($173m) as part of the agreement.
Equity capital for the project was provided by the three owners.
Contractors involved with the Nordergrunde project
WPD contracted Senvion, a wholly-owned subsidiary of Suzlon, for the supply of 18 6.2M126 turbines for the Nordergrunde offshore wind farm in 2015.
Bilfinger Marine and Offshore Systems was awarded a contract worth approximately €30m ($33m) for the installation of steel foundations and the transportation of the wind turbines to the installation site.
General Cable’s fully owned subsidiary Norddeutsche Seekabelwerke (NSW) delivered and installed subsea medium-voltage cables at Nordergründe, under a contract awarded in July 2015.
AMBAU was contracted for manufacturing the monopiles and transition pieces. BVT was awarded the substation construction contract. BVT, however filed for insolvency in 2016, thus the construction of the substations was completed by WPD. The North Sea grid operator Tennet supplied the on-shore and offshore cables.
WPDengaged law firm Blanke Meier Evers as its legal adviser with regards to the conception, drafting, negotiation and conclusion of the supply, and construction contracts of the Nordergründe wind farm.
