The Belwind Phase 1 offshore wind farm is located approximately 50 km off the Belgian coast on the Bligh Bank in water depths of 15 - 37 m. The wind farm includes one offshore high voltage station and 55 turbines, providing approximately 500 GWh per year. This is equivalent to the consumption of some 175,000 housholds and saves the emission of 270,000 tonnes of CO₂ per year.
Engineering, procurement and construction (EPC)
Van Oord, as EPC Contractor, was responsible for the design, engineering, procurement and installation of the 56 foundations, the power cables and the complete electrical infrastructure, including OHVS and grid connection onshore. Furthermore, Van Oord was responsible together with Vestas for the turbine installation. Having a lot of experience in offshore construction and installation, Van Oord managed to build and construct the Belwind offshore wind farm in a record time of 15 months after Financial close.
Project execution commenced in August 2009. In March 2010, the 56 foundations (55 for the turbines, one for the OHVS), consisting of monopiles and transition pieces were successfully installed by the heavy lift vessel Svanen and the jack-up platform JB 114.
The monopiles have a diameter of 5 m, a weight of approx. 400 tonnes each, with lengths varying from 50 up to 70 m. The monopiles were sealed with hydraulic plugs to enable floating transportation with tugs from Zeebrugge port to the offshore wind farm. At the offshore site the plugs were removed and the Svanen has driven the monopiles into the seabed, making use of a hydraulic piling hammer. To prevent sea life / marine life from being harmed, underwater sound signals were emitted.
After Monopile installation was completed, transition piece installation commenced. Each transition piece has a weight of approximately 185 tonnes and has a boat landing and platform. The JB 114 transported the transition pieces (three at a time) from Zeebrugge port to the Belwind Offshore Wind Farm. Once the JB 114 arrived on site, the platform elevates itself out of the water. As a result, the barge is no longer affected by wave heights and is a stable platform to install the transition pieces on top of the monopiles with a heavy crane.
OHVS, onshore booster station and scour protection
The Offshore High Voltage Station is a transformer station at sea. Weighing 1,100 tonnes, the OHVS - including a tuned mass damper - was installed on one of the foundations by the Taklift 4. Onshore, Van Oord has built a booster station for reactive power compensation. The development of scour holes around the foundations is prevented by subsea rock installation. In total 132,000 tonnes of scour protection has been placed by the vessel HAM 601.
The wind turbines in the park are connected with so called infield cables. These cables were installed by Van Oord’s vessel HAM 601 and buried into the sea bed by the CS Sovereign. The infield cables are installed in five strings of ten turbines and one string of five turbines. The cables are connected per string to the OHVS. Total length of all infield cables amounts to 50 km. From the OHVS an export cable runs to the mainland of Belgium. This 52 km long cable with a diameter of approx. 25 cm has been installed by the vessel Skagerak.
For crossing the shipping lane between Zeebrugge, Antwerp and Vlissingen a 1,200 m long and 7 m deep trench had to be dredged in order to enable future widening and deepening of the shipping lane. The dredging works were executed by Van Oord’s trailing suction hopper dredger Geopotes 14. The electricity runs through the export cable from the OHVS to the electricity grid onshore. From there green electricity is distributed to the consumers.
55 wind turbines
The 55 Vestas V90 wind turbines were mostly assembled on the mainland and transported by the JB 114 from Zeebrugge port to the Belwind Offshore wind farm. The JB 114 installed the turbines on top of the foundations. The total height of the turbines, including the blades, is approximately 117 m above sea level. The total height of the entire construction reaches approximately 190 m. In December 2010 the Belwind Phase 1 Offshore Wind Farm became officially operational.