Borkum Riffgrund 2 Offshore Windfarm, North Sea

Borkum Riffgrund 2 is an offshore windfarm being developed 54km off the coast of Lower Saxony in the North Sea, Germany. The project will be located next to the existing Borkum Riffgrund 1 windfarm.

 The substation platform will be supported by a 1,700t four-legged jacket. Credit: Orsted

The substation platform will be supported by a 1,700t four-legged jacket. Credit: Orsted

Borkum Riffgrund 2 is jointly owned by Global Infrastructure Partners (GIP – 50%) and Orsted (formerly DONG Energy – 50%), with the latter being the developer. The final investment decision for the windfarm was taken in June 2016, while commissioning is expected in the first half of 2019.

The offshore windfarm is expected to be operated from DONG Energy’s base in Norddeich. It will have a total capacity of 450MW and will produce sufficient electricity to power approximately 460,000 German households a year.

Borkum Riffgrund 2 windfarm details

The windfarm will be installed with 56 V164-8.0 MW MHI Vestas wind turbines with a capacity of 8MW each. The turbine blades are 80m-long, weigh 35t, and have a total swept area of 21,124m². The 390t nacelle of the turbine is 20m-long, 8m-wide, and 8m-high.

The turbines have a hub height of 105m and a tip height of 187m, while they are planned to be installed on suction bucket jackets.

The offshore windfarm will also include a high-voltage AC transformer substation, which will step-up the electricity generated and transfer it onshore.

Borkum Riffgrund 2 windfarm substation details

The substation will have a total capacity of 450MW and will include a platform with topsides measuring 25m x 40m x 20m and weighing 2,500t. The topsides will comprise five decks, including a cellar deck for cable pulling and cable hang-off.

“It will have a total capacity of 450MW and will produce sufficient electricity to power approximately 460,000 German households a year.”

The substation platform will be supported by a four-legged lattice jacket measuring 30m x 30m x 55m and weighing 1,700t. It will be installed on a foundation consisting of 18 piles, which weigh 1,050t and 63m-high.

The substation will be installed with a dehumidification system, ventilation system, heating and cooling system, and heating, ventilation and air conditioning (HVAC) control systems. It will have a lifespan of 25 years and will be made of high-quality materials such as stainless steel and titanium.

Power transmission from Borkum Riffgrund 2 windfarm

The Borkum Riffgrund 2 windfarm substation will collect and export the high-voltage current generated to the DolWin alpha HVDC converter platform through 30km cables.

DolWin will deliver the power onshore through an 83km subsea cable to the converter station located in Dörpen / West in Lower Saxony and connected to the national power grid.

Financing for Borkum Riffgrund 2 wind farm

A group of institutional investors provided €832m ($1.04bn) in debt financing for the project. Some of the investors include DekaBank, Edmond de Rothschild AM’s BRIDGE platform, La Banque Postale Asset Management, NN Investment Partners, and Wiener Städtische Versicherung.

Contractors involved

MHI Vestas Offshore Wind was contracted to supply the turbines for the project, while Fred Olsen Windcarrier has been contracted to transport and install the 56 wind turbines.

The suction bucket foundations for the turbines are being provided by Norwegian Geotechnical Institute (NGI), while ST³ Offshore was contracted to fabricate the foundations.

ISC Innovative Engineering carried out the detailed designing for the substation of the windfarm.

HSM Offshore was awarded the engineering, procurement and construction contract for the platform, while Heinen and Hopman will fabricate and install the platform.

Siemens Convergence Creators was contracted to supply and maintain the SCADA Network and telecommunication system.

Other contractors involved in the project are Iv-Oil and Gas, Iv-Consults, Observator Group, Bladt Industries, Hellenic Cables Group, Seaproof Solutions, ABS Group, MacArtney, Heerema Marine Contractors, Peutz, InterDam, GeoSeam, and RSB Formwork Technology.