Alpha Ventus: Germany’s First Offshore Wind Farm

Federal Environment Minister Dr. Norbert Röttgen together with Chief Executive Officers Dr. Werner Brinker of EWE, Dr. Wulf Bernotat of E.ON and Tuomo Hatakka of Vattenfall Europe are commissioning Germany’s first offshore wind farm during a ceremony in Norddeich.

Alpha Ventus is the first open sea wind farm of its kind in Germany’s territorial waters. It marks the beginning of a new era in environmentally-friendly wind power generation in Germany – far from the coast in the open sea, in deep-sea conditions and utilising cutting-edge technology.

Alpha Ventus was constructed 45 kilometres off the coast of the island of Borkum by a consortium of EWE, E.ON and Vattenfall Europe, who together have invested 250 million Euros to bring this wind energy project to its successful completion.

Alongside wind power generation, Alpha Ventus also serves as a test field for research projects concerned with nature conservation, which are aided by the Federal Ministry for the Environment. Additionally, the wind farm will provide invaluable knowledge as regards the utilisation and the further development of offshore wind power

On the occasion of the official commissioning of Alpha Ventus, Federal Environment Minister Dr. Norbert Röttgen says: "The use of wind power will play a key role in the energy mix of the future. Offshore wind farms are a decisive factor in this role. Our goal is an installed offshore capacity of 25,000 MW by the year 2030. Alpha Ventus is the beginning, the pioneering work which has truly opened the door for us into the age of renewable energies. Investors, turbine manufacturers and grid operators have all taken a great risk with this test field. Their steadfast commitment, perseverance and creativity have paid off: The experience gained during the construction of alpha ventus will benefit all future offshore wind farms.”

Alpha Ventus has already had a direct influence on the subsequent projects of EWE, E.ON and Vattenfall, as Dr. Werner Brinker, CEO of EWE AG, explains:

“Today, with the commissioning of Alpha Ventus, we are crowning an exemplary pioneering project. With it we are giving the starting signal for the use of ocean wind power in the German North Sea. Offshore technology is the topic of the future, with excellent innovation and growth potential and offering tremendous opportunities. We want to be a part of this future and therefore actively drive its development forward – with reference projects like alpha ventus and with investments in additional offshore wind farms, as, for example, in the construction of Riffgat, 15 kilometres from Borkum.”

Dr. Wulf Bernotat, CEO of E.ON AG, declares: “Alpha Ventus is a great step forward for the expansion of wind power on the open sea. With this pioneering project, we at E.ON have improved our excellent offshore experience in coastal area wind farms into true, open sea know-how, so that we can now tackle additional offshore deepwater projects in the German North and Baltic Seas."

Tuomo Hatakka, CEO of Vattenfall Europe AG: “This is a great day for offshore wind power in Germany. Our companies have exhibited excellent team spirit and with alpha ventus have proven that the use of offshore wind power is viable, even in the harsh natural conditions in Germany. Vattenfall is already a global leader in the field of offshore wind industry today. Power generation from wind turbines is an essential building block of Vattenfall’s strategy, ‘Making Electricity Clean’, through which we aim to make our electricity generation carbon neutral by 2050.”

Key data Alpha Ventus wind farm

– Number of wind turbines: 12
– Total capacity: 60 MW
– Expected energy yield per annum: ca. 220 gigawatt/hours (= annual energy consumption of about 50,000 three-person households

Technical data Multibrid M5000
– Rotor diameter: 116 m
– Height of hub: 90 m
– Total height above seabed: 178 m
– Rated output: 5 MW
– Speed: 5.9 – 14.8 rpm
– Cut-in wind speed: 3.5 m/s (= force 3)
– Rated wind speed: 12.5 m/s (= force 6)
– Cut-out wind speed: 25 m/s (= force 10)
– Blade tip speed: 90 m/s (= 300 km/h)
– Weight of nacelle without rotor and hub: 200 t
– Weight of nacelle with rotor and hub: 309 t
– Weight of steel in tripod, tower, nacelle: 1,000 t
– Tripod: Weight of steel: 700 t; Height: 45 m; Piles: 35-45 m

Technical data REpower 5M
– Rotor diameter: 126 m
– Height of hub: 92 m
– Total height above seabed: 185 m
– Rated output: 5 MW
– Speed: 6.9 – 12.1 rpm
– Cut-in wind speed: 3.5 m/s (= force 3)
– Rated wind speed: 13.0 m/s (= force 6)
– Cut-out wind speed: 30 m/s (= force 11)
– Weight of nacelle without rotor and hub: 290 t
– Weight of nacelle with rotor and hub: 410 t
– Jacket foundation: Weight of steel: 500 t; tower: 210 t;

Technical data transformer station
– 30 m: elevation of helipad
– 25 m: elevation of main deck with crane, substation control and protection (I&C) / switchgear plant / neutral earthing transformer, fire extinguishing system, MV and LV systems, emergency generating set, MVAr throttle / 110 kV GIS (gas-insulated switchgear) system (AREVA)
– 21 m: cable deck with workshop, equipment room, lounge, diesel tanks, emergency generating unit, cable bench and oil sump
– Cable deck and main deck: 110/30 kV transformator 75 MVA (AREVA)
– Jacket foundation: approx. 750 t
– Foundation piles: 35 m long, 2.7 m diameter, 100 t apiece
– Position: N 54°00′, E 6°37.40′
Assembly sites and suppliers of Multibrid M5000

Foundation: assembly site Verdal, Norway
– Sif Group bv, Roermond, the Netherlands: tubular tripod elements
– Aker Solutions, Verdal, Norway: tripod foundations
– Offshore Wind Technologie GmbH (OWT), Leer, Germany: engineering of foundation structure and tower jacket; offshore logistics
– MENCK, Kaltenkirchen, Germany: underwater ramming

Tower: assembly site Bremen
– Ambau GmbH, Bremen, Germany

Nacelle: assembly site Multibrid GmbH, Bremerhaven
– ABB Oy, Helsinki, Finland: generator
– ABB Schweiz AG, Baden, Switzerland: converters
– Pauwels Trafo Belgium NV, Mechelen, Belgium: transformers
– Siempelkamp Giesserei GmbH, Krefeld, Germany: machine housings and lower deck
– Renk AG, Augsburg, Germany: gearing
– Friedrich Wilhelms Hütte GmbH, Mülheim an der Ruhr, Germany: hub
– Ferry-Capitain, Joinville, France: hollow shaft
– REETEC GmbH, Bremen, Germany: installation and medium-voltage work
– Bode & Wrede GmbH, Dingen, Germany: engineering of jig-making & lifting accessories
– µ-Sen GmbH, Rudolstadt, Germany: online condition monitoring systems (CMS) for the wind power plants

Rotor blades: assembly site Stade
– PN Rotor GmbH, Stade, Germany: rotor blade and composites engineering

Assembly sites and suppliers of offshore transformer station
Assembly site for the transformer station and its platform is the Braunschweig Quay in Wilhelmshaven, Germany (March – September 2008)

Transformer station
– AREVA Energietechnik GmbH, Bremen / Dresden, Germany: complete electrotechnology for the 110/30 kV offshore transformer station, including transformers

Transformer platform and its offshore installation
– Consortium comprising Bilfinger Berger AG (Mannheim, Germany), Hochtief Construction AG (Essen, Germany) and WeserWind GmbH (Bremerhaven, Germany)

Transformer platform suppliers:
– IMS Ingenieurgesellschaft mbH, Hamburg, Germany: engineering of jacket & topside
– Mostostal, Crakow, Poland: topside prefabrication
– BVT Brenn- und Verformtechnik Bremen GmbH, Bremen, Germany: helipad

Submarine cables for intra-farm cabling
– NSW (Norddeutsche Seekabelwerke), Nordenham, Germany: production and laying

Erection fleet Transformer station:
– Floating crane (sheerlegs): Smit Heavy Lift, Rotterdam: "Taklift 4"
– Hochtief Construction AG: "Odin" jack-up platform

Erection fleet Multibrid M5000:
– Pusher/Barge Mega Motti
– Floating crane (sheerlegs): “Samson” (Danish Salvage & Towing Company DBB, Aarhus)

Maritime Safety Zone:
The offhore windfarm lies between the Traffic Separation Schemes "Terschelling-German-Bight" and TSS "German Bight Western Approach" within the German Exclusive Economic Zone (EEZ). The Federal Maritime and Hydrographic Agency has established a safety zone around the offshore wind farm “. The safety zone regulations became effective in August 2008. The safety zone extends 500 m around the wind farm and will be guarded by the guard vessel "Otto Treplin".

Norden-Norddeich operations control center:
Instrumentation & control:
– BTC Business Technology Consulting AG, Oldenburg, Germany:
integrated wind power plant control and management system for offshore wind farms

Shipping operations:
– Reederei Frisia

Helicoper operations:
– HTM Helicopter Service

Grid connection:
The grid connection will be effected by transpower GmbH.

Submarine Cable: Oceanteam Power & Umbilical, Wilhelmshaven facility, Germany
– "Team Oman" cable-laying vessel
– "Oceanteam Installer" cable-laying barge
– Producer of 110 kV submarine cable: Prysmian Cables and Systems