The growth of wind power in Europe is running out of space, both at inland and coastal locations. Logically, the next step is to develop offshore wind farms at sea. These installations are placed several kilometres off the coast and fixed to the continental shelf.
There they are free-standing in the wind and so can achieve a high energy yield. However, constructing and operating these installations poses unprecedented challenges for the technology used. Where water is up to 60m deep, stable foundations have to be built on the sea bed and the construction of the wind turbines themselves, with their tower, power house and rotor blades, requires elaborate assembly. It cannot be done from an unstable ship or platform, for obvious reasons.
In order to get around these problems, the VAN OORD Group decided to place an order at the Sietas shipyard in Hamburg to build a special assembly ship. Not only can the 139m long ship be positioned on the seafloor with four hydraulic columns, the ship, which has been named "AEOLUS", also features a staggeringly large deck crane made by TTS NMF in Hamburg.
The boom is constructed from a double length of grid segments and can lift 900t for a load radius of 30m. When using the maximum radius of 80m, it can still lift an enormous 240t. NMF would not compromise when it came to selecting the hoisting and adjusting ropes and picked CASAR products as proven, reliable components for this application.
For the hoisting rope, there is a CASAR POWERPLAST with a 66mm diameter and eight-ply reeving with a heavy-duty cylinder. As well as having outstanding rotation resistance, this rope stands out thanks to the special plastic casing of its core rope with excellent corrosion protection of the inner strands and substantial insensitivity to dynamic loads.
The crane boom is adjusted with a CASAR TURBOPLAST, also with a 66mm diameter, which is another popular and proven choice of rope for deck cranes. Both of these rope types have compacted outer strands, thereby offering high breaking strength, excellent coiling and drum compression resistance for multiple layer coiling. With Aeolus, the top priority was maximum operational safety and reliability for all components. Tough operating conditions in the North Sea will push the ship, its crane and ultimately its ropes to their limits when performing the often difficult assembly manoeuvres.
In addition to the Aeolus, two semi-submersible flotels known as AXIS VEGA and AXIS NOVA will also be used, serving as stationary accommodation for the construction and service staff and designed to cope well with extreme weather conditions.
For the necessary hoisting work, the flotels will also be fitted with appropriate crane equipment from TTS NMF. The planned 70t cranes will operate a similar combination of products as the AEOLUS, with a 42mm CASAR POWERPLAST as the main hoisting rope and a 42mm CASAR TURBOPLAST as the adjusting rope. The ropes also include a 30mm CASAR POWERPLAST as a secondary hoisting winch.