BARD Offshore I (BO1), North Sea

Aerial view of Germany's 400MW BARD Offshore 1 wind farm. Image: courtesy of BARD.

BARD Offshore 1 is installed with 80 BARD 5.0MW turbines. Image: courtesy of BARD.

Each rotor has a diameter of 122m. Image: courtesy of BARD.

The Borwin I (Alpha) platform serves the BARD Offshore 1 wind farm. Image: courtesy of BARD.

Bard Offshore 1, located 100km north-west of Borkum Island in the German North Sea, is the world's remotest offshore wind farm. Image: courtesy of BARD.

The hotel ship Regina Baltica provided accommodation to the workers during the construction phase. Image: courtesy of BARD.

The installation works were performed employing four jack-up barges and more than 12 support vessels. Image: courtesy of BARD.

BARD Offshore I (BO1) wind farm is located approximately 100km north-west of Borkum Island in the North Sea, covering an area of approximately 60km². It is Germany’s largest operating offshore wind farm and is the world’s most remote offshore wind farm.

The 400MW offshore wind farm is capable of generating 1.6bnkW/h of energy a year, serving the energy needs of approximately 400,000 households, which is equivalent to reducing one million tonnes of CO₂ emissions a year.

The construction of BO1 began in April 2010 and the first turbine was connected to the grid in December. The construction works were completed in August 2013, one month ahead of schedule, leading to its formal inauguration in the same month.

BARD Offshore I was developed by Bard, and is owned and operated by Ocean Breeze Energy. Service and maintenance services for the wind farm are rendered by Offshore Wind Solutions (OWS).

Financing for the German North Sea-based project

The overall investment on the project exceeded €1bn (approximately $1.12bn). HypoVereinsbank was the long-term financial partner for the project, while a €53.1m ($65m) grant was also received under the European Energy Programme for Recovery (EEPR) from the European Commission.

BARD Offshore I make-up and construction details

BARD Offshore I is equipped with 80 Bard 5.0 wind turbines, rated at 5MW each. Each turbine features a three-bladed rotor with a circle diameter of 122m.

The turbines were constructed using 120,000t of steel and are installed at water depths ranging between 40m and 44m. The hub height of the turbines above water is 90m. The overall height of the turbines above water is 152m.

Each turbine is supported by a tripile-foundation structure weighing 490t and consisting of three 3.35m diameter piles connected to a transition piece. The piles are between 84m and 91m-high and are laid 40m underwater.

The project also involved the construction and installation of the Borwin I (Alpha) platform, as well as installation of two 125km-long subsea cables and two 75km-long onshore underground cables. The Borwin I (Alpha) platform has accommodation facilities for 40 people and features a helicopter deck.

The installation works at the offshore site were performed employing four jack-up barges, namely Windlift, JB 115, JB 117 and Thor, assisted by SWE Offshore’s Regina Baltica hotel ship and more than 12 support vessels.

BARD Offshore I grid connection details

The output from the offshore wind farm is transmitted to the 170kV Borwin I (Alpha) platform’s high-voltage direct current (HVDC) light converter station via a 36kV AC cable system. Output is then transmitted to the 380kV Diele substation onshore, 75km from the coast, before being conveyed to the 380kV German national grid.

The project’s transmission facilities are operated by the network operator TenneT.

Contractors involved with BARD’s offshore wind farm

The system engineering, as well as design, supply and installation of the offshore converter station, sea and land cable systems, and the onshore converter station were performed by ABB.

Harland and Wolff fabricated the 7,739t Borwin I (Alpha) platform for the project under a subcontract from Weserwind. Rotork Holland supplied its proprietary IQTPro actuators for the transformer platform.

SGL Rotec, a joint venture between Abeking & Rasmussen Schiffs- und Yachtwerft and SGL Group, supplied the rotor blades. Cuxhaven Steel Construction supplied the foundation structures for the turbines, while BLRT Grupp / Marketex shipped them to the project site.

EEW Special Pipe Constructions constructed and supplied the transition pipes. Norddeutsche Seekabelwerke (NSW), a subsidiary of General Cable Corporation, supplied the submarine medium and high-voltage cables. Tekmar Energy supplied its proprietary Teklink system for protecting the array cables.

The cable laying contract was awarded to Deep Ocean, while DOC Offshore provided construction supervision and package management services.

The self-stabilising platforms for providing offshore access to the crews were provided by Ampelmann. They are fitted on the VOS Sympathy vessel provided by Vroon.