The Canada-based independent energy supplier Northland Power has opted for one of the most powerful offshore turbines. The 8.4 megawatt turbine with a rotor diameter of 164 metres optimizes wind yield. The North Sea wind farm Deutsche Bucht is expected to produce approximately 1 billion kilowatt hours of renewable energy each year, enough to supply about 300,000 households, saving 700,000 tonnes of greenhouse gas emissions.
Each of the 31 turbines has three 80 metre rotor blades, which corresponds to the length of nine London double-decker buses lined up in a row. The rotor area, i.e. the area described in the air by the rotors, is 21,124 m2, which is larger than the London Eye Ferris wheel. The height of the turbines is also enormous: The hub to which the rotors are attached, is a good 100 metres above the water level. The tip of the rotor blade is almost 190 metres above the water.
The turbines are designed to make efficient use of the wind. They switch on automatically from a wind speed of 4 metres per second and start to generate electricity. They reach their peak output of 8.4 megawatts at 13.5 metres per second. In severe storm conditions, i.e. if the wind reaches speeds of 31.5 meters per second, which equivalents to 113 kilometres per hour, the turbines will automatically shut down for safety reasons. Incidentally, the tips of the rotor blades reach a maximum speed of around 325 kilometres per hour.
The marshalling harbour for the turbines was located in the Danish port of Esbjerg. The individual major components – rotor blades, hubs, nacelles and tower segments – were transported to Esbjerg from their places of manufacture. Pre-assembly of the towers was also carried out in the base port. The components were transported by offshore installation vessel to the offshore wind farm and installed.
On behalf of Northland Deutsche Bucht, K2 Management was responsible for project management during the construction phase.
Manufacturing and installation
Operation and maintenance
Maintenance work on offshore turbines has to be well planned, due to the distance to the mainland and the weather conditions in the North Sea; 24-hour monitoring ensures constant online supervision during operation. An early warning system indicates malfunctions or possible technical problems in time to enable offshore service deployments to be well planned.
Northland and the turbine manufacturer, MHI Vestas Offshore Wind Germany GmbH have executed a service and maintenance contract for a term of 15 years to ensure smooth operation of the turbines.