Horns Reef 2

Location and Geography

• The Horns Rev 2 offshore wind farm is located in the North Sea, approximately 30 kilometers west of Blåvands Huk, which is the nearest coast in western Denmark.
• The wind farm is situated on the western part of the Horns Rev reef and extends towards the north from the reef.

Technical Specifications

• Number of Turbines: The wind farm consists of 91 wind turbines of the type Siemens SWT-2.3-93, each with a capacity of 2.3 MW.
• Total Capacity: The total nominal power output of the wind farm is 209.3 MW.
• Turbine Details:
  • Tower height: 68 meters
  • Hub height: 68 meters
  • Blade length: 45 meters
  • Rotor diameter: 93 meters
  • Nacelle length: 16 meters
  • Weight of each blade: 12 tonnes
  • Weight of nacelle: 80 tonnes
  • Weight of tower: 92 tonnes
  • Weight of foundation: 150-200 tonnes
  • Total weight of each wind turbine: approximately 400 tonnes.
• Foundation: The wind turbines are installed on fixed monopile foundations.

Performance and Production

• Annual Production: The wind farm generates approximately 800 million kWh (800 GWh) of electricity per year, which is enough to power around 200,000 households.
• Wind Speeds:
  • Cut-in wind speed: 4 m/s (gentle breeze)
  • Full production at: 13 m/s (high winds)
  • Cut-out wind speed: 25 m/s (storm).

Construction and Operation

• Construction Period: The construction of Horns Rev 2 began in May 2008 and was completed by September 2009.
• Developer and Operator: The project was developed and is operated by Ørsted (formerly DONG Energy).
• Contractors Involved:
  • Siemens Gamesa Renewable Energy: Supplier of the wind turbines and O&M contractor.
  • A2SEA A/S: Supplier of vessels for installation of wind turbines and foundations.
  • Semco Maritime A/S: Supplier of the accommodation platform.
  • Nexans Deutschland Industries GmbH & Co. KG: Supplier of cables.
  • Visser & Smit Hanab bv (Global Marine Systems Ltd.): Supplier of cable installation.
• Accommodation Platform: For the first time in history, an accommodation platform was installed in connection with an offshore wind farm. This platform is a 750-square meter, three-storey facility that can accommodate 24 people for several weeks, including amenities such as single rooms, shower facilities, kitchen, dining room, TV lounge, gym, and technical room.

Environmental and Maintenance Aspects

• Environmental Impact: The wind farm is located in an area with water depths varying between 9 and 17 meters. The environmental impact assessment (EIA) was conducted to ensure minimal disruption to the marine environment.
• Maintenance: The wind farm is unmanned during ordinary operation, with remote monitoring performed from an onshore control room. Regular inspections and maintenance are carried out at intervals of 6-12 months, with annual overhauls during the summer months.

Economic and Climate Impact

• Total Construction Costs: The project cost approximately DKK 3.5 billion.
• Power Purchase Agreement: The power generated from the project is sold to Novo Nordisk under a power purchase agreement.
• Climate Impact: The project contributes significantly to reducing CO2 emissions and is part of Denmark's ambitious plans to increase offshore wind power capacity. It was also the first large-scale offshore wind farm project to be part of a climate partnership, where each climate partner contributed to the project economy by committing to long-term procurement of power from the wind turbines.

Additional Features

• Innovative Practices: The project utilized innovative practices such as placing the turbines in a fan-shaped formation to maximize wind capture, adjustable generators to suit wind conditions, new methods for array cable installation, and the use of both steel and concrete foundations to withstand extreme sea conditions.
• Area and Layout: The wind farm covers an area of approximately 35 square kilometers, with the turbines spaced about 500 meters apart.