Sandbank

Location and Geography

The Sandbank Offshore Wind Farm is situated in the German part of the North Sea, approximately 90 kilometers west of the island of Sylt and off the coast of Schleswig-Holstein. It is located in an exclusive economic zone and operates in waters with depths ranging from 25 to 37 meters.

Ownership and Investment

The Sandbank Offshore Wind Farm is a joint venture between Vattenfall, which holds a 51% stake, and Stadtwerke München (SWM, Munich city utility), which holds the remaining 49%. The total investment for the project was around EUR 1.2 billion, with Vattenfall's investment being approximately EUR 600 million (or about $818 million).

Capacity and Turbines

The wind farm consists of 72 Siemens SWT-4.0-130 wind turbines, each with a capacity of 4 MW. This gives the farm a total installed capacity of 288 MW. The turbines have a rotor diameter of 130 meters and a height of 158 meters to the blade tip from sea level. The blades are made of aeroelastic material, reducing their mass by up to 20%.

Power Production and Impact

The Sandbank Offshore Wind Farm produces up to 1.4 TWh of electricity per year, which is sufficient to power approximately 400,000 households. This production also helps in reducing carbon emissions by about 1.5 million tonnes annually.

Construction and Commissioning

Construction on the wind farm began in June 2015, with the first turbine installed in July 2016. The project was completed and commissioned in January 2017, with full operations starting in July 2017.

Infrastructure and Maintenance

The wind farm uses monopile foundations for the turbines. A specially designed service operation vessel (SOV) is placed between the DanTysk and Sandbank wind farms, providing accommodation facilities and a workshop with spare parts. Technicians can ferry between land, the service vessel, and the turbines using helicopters. The maintenance costs are expected to be minimal due to the shared infrastructure and facilities managed from the service harbor in Esbjerg.

Contractors and Suppliers

Key contractors involved in the project include:

• Siemens: Supplied the 72 wind turbines and provided maintenance services for the first five years of operation.
• ABB: Designed, engineered, supplied, and installed the transmission link, including a subsea AC cable system.
• Visser & Smit Marine Contracting (VSMC): Supplied cables, CPS, and performed installation, post-lay burial, and termination and testing of infield cables.
• Rambøll: Designed the monopiles.
• EEW Special Pipe Constructions and Bladt Industries: Produced the monopiles and transition pieces.
• Bilfinger Construction: Installed the turbine towers.
• MPI Contractors: Provided the turbine installation vessel.
• Seaway Heavy Lifting: Provided transportation and installation services for the substation.

Operations and Work Environment

Technicians working on the wind farm typically operate on 14-day shifts, living and working on an offshore accommodation platform. Daily operations involve traveling to the turbines via crew transfer vessels (CTVs) if weather conditions permit. The work is highly physically demanding and requires technicians to be skilled in rope access, work-at-height, and emergency response techniques. They must also use personal protective equipment (PPE) and survival suits to protect against harsh weather conditions.

Synergies and Shared Resources

The Sandbank wind farm, along with the DanTysk and other nearby wind farms like Horns Rev, benefits from shared resources and infrastructure. This includes using the same vessels, infrastructure, and facilities managed from the service harbor in Esbjerg, enhancing operational efficiency and reducing costs.