Butendiek

Location and Overview

The Butendiek Offshore Wind Farm is located in the German part of the North Sea, approximately 32 kilometers west of the island of Sylt and 53 kilometers from the mainland, near the German-Danish maritime median line.

Capacity and Turbines

The wind farm consists of 80 Siemens wind turbines, each with a capacity of 3.6 MW, resulting in a total installed capacity of 288 MW.

Construction and Operation

Construction of the Butendiek Offshore Wind Farm began in early 2014 and was completed in September 2015, when the farm entered into commercial operation.

Ownership

The project is owned by several entities, including:

• Industriens Pensionsforsikring: 22.5%
• Siemens Financial Services: 22.5%
• Itochu Corp: 15%
• CITIC Group Corp: 11.25%
• CDC Infrastructure: 10%
• Skyborn Renewables: 7.5%
• Octopus Energy: 4.9% and others.

Infrastructure and Installation

• Foundations: The wind turbines are installed on fixed monopile foundations. The installation process involved laying a filter layer for scour protection, transporting and driving the monopiles into the seabed, and connecting them to the lifting gear.
• Offshore Substation: The substation was installed in two parts: the jacket foundation anchored to the seabed with four piles, and the topside welded to the jacket. The heavy lift vessel Rambiz was used for this process.
• Cabling: Cables were laid section by section between the foundations, pulled into the monopiles, and then buried into the seabed.
• Turbine Installation: The installation vessel Bold Tern was used to transport and install the turbines in a five-step process involving the tower, nacelle, and three rotor blades.

Operations and Maintenance

As of January 1, 2024, Semco Maritime has secured a 10-year balance-of-plant, operations, and maintenance service contract for the Butendiek wind farm. Siemens Gamesa holds the contract for full turbine maintenance and offshore logistics. The service work includes scheduled and unscheduled maintenance and inspections above water on the offshore substation and its foundation, as well as on the wind turbine generator foundations. Operations will mainly take place from Havneby on the Danish Island Rømø.

Environmental Impact

The Butendiek Offshore Wind Farm generates approximately 1,290,000 MWh of electricity annually, which is enough to power around 370,000 households. It offsets about 325,452 tons of carbon dioxide (CO2) emissions per year.

Contractors Involved

• Turbine Supplier: Siemens Gamesa Renewable Energy provided 80 units of SWT-3.6-120 turbines.
• Operations & Maintenance: Initially, Deutsche Windtechnik and Siemens Gamesa Renewable Energy were contracted for operations and maintenance services. As mentioned, Semco Maritime has taken over some of these responsibilities starting from 2024.

Developer

The project was developed by Skyborn Renewables, a subsidiary of Global Infrastructure Partners LLC, which is headquartered in Bremen, Germany.