High seas

The C-Power Thornton Bank offshore wind farm is 27 to 30 km off the Belgian coast in the North Sea and has a total capacity of 300 MW. Fully erected, the 325 tonne turbine nacelles stand 120 m above the seabed and the development will provide enough energy for 600,000 people.

Sarens was commissioned to carry out the projects by Geosea, specialist offshore contractor for the DEME Group.

In April and May 2008, the company transported the six 3,000 tonne, 42 m high, foundations from their fabrication site using Kamag self propelled modular transporters (SPMT), which were then loaded to the 4,000 tonne Rambiz crane vessel and shipped to Thornton Bank.

For assembly of the steel towers and turbine parts on their foundations, Sarens erected a 750 tonne capacity Liebherr LR 1750 onto its 40 m high Sarens Multi-Lift Tower (SMLT), which was erected on the Buzzard jack-up barge.

Multi-lifting

Three cranes assisted in the operation, which took place some 20 km down the Belgian coast in Zeebrugge, throughout June. They were a 200 tonne Terex Demag AC 200-1 all terrain, a Terex Demag TC 1100 truck crane and a 550 tonne Liebherr LG 1550 crawler. The latter crane also helped to assemble the rotor constructed from hub and blades.

The TC 1100 was then placed on a barge used to transport the rotors to the wind farm. On site, the TC 1100 acted as a tail crane to stabilise the blades as they were lifted by the LR 1750.

Back at Oostende, a 600 tonne Terex Demag CC 2800-1 crawler was used to load tower sections and nacelles onto a second transport barge. A test lift was carried out at the beginning of July and, at the time of writing in late July, the actual lifts were due to be completed mid-August. Production is due to start in September.