OFFSHORE WIND Ӏ SECTOR REPORT
j remotely handled from onshore. With no need for a human crane operative, safety and economy are greatly increased. “A common factor in all
offshore operations is space,” says Fröbe. “It is at an absolute premium at sea and on the support vessels and platforms.” For that reason the CAR has been devised. CAR stands for Crane Around
Leg. Jack-up installation vessels stabilise themselves, and raise themselves above the water, by extending four or more legs down to the seabed. The legs extend also above the deck; the slewing ring of the crane fits around the leg, and using the legs as a central column down the middle of the on-board crane is a sensible space-saving design that leaves the vessel deck completely free. Liebherr’s CAL 6400 has a capacity of 1,700t and jib length of 108m and can be used, for example, to lift three- blade turbine assemblies up for installation on the nacelle. Dutch offshore specialists Huisman also have cranes on the same principle – they call theirs LECs, for Leg Encircling Cranes. In November 2021 they received an order, from offshore installation specialists Van Oord, for their largest LEC yet, in terms of capacity, boom length and power. To be fitted to the company’s new installation jack-up vessel to be called Boreas, it will be able to lift over 3,000 tonnes to install 20 MW turbines and their foundations. Components to build as many as seven turbines will be carried on board the vessel. A similar but smaller Huisman crane is already in operation on Van Oorde’s sister vessel the Aeolus. So many and so varied are the challenges involved in offshore wind farm lifting that Mammoet have launched a competition to find the most imaginative and innovative ways of doing so.
42 CRANES TODAY
Floating wind farms: the logical next step...
A major constraint on wind farms up till now has been the necessity of siting them in shallow water, where the monopiles can be set into the seabed. Floating turbines that can be installed in deep waters would open many more areas for wind farms, further from shore, in areas up to 800m deep and with stronger winds. The world’s first floating wind farm, with 5 turbines off Scotland about 15 miles from Peterhead has been delivering electricity since 2017. Spain and Japan are moving forward strongly in the market; France has set a goal to become world leader in the technology and is committed to projects of Brittany and the Mediterranean Sea. Energy company EDF Renouvelables has been developing a pilot project off Port-Saint-Louis- du-Rhône near Marseilles in the Mediterranean. The Provence Grand Large project is for three 8.4 MW wind turbines, supplied by Siemens-Gamesa, on floats designed, manufactured, and installed by SBM Offshore. The turbines will be installed 17 km from the shore; 19 km of submarine cable and 9 km of underground cable will connect it to the public grid. Heavy lift and transport specialist Schmidbauer has been handling the heavy load logistics of the
prototype turbines. Schmidbauer has been developing a concept for the installation of the floating turbines as well as the handling of the components in the harbour before the turbines are brought out to sea. The company provides a LR 11350 crawler crane, a CC 2400-1 crawler crane, 130-t auxiliary cranes, and a 48-axle SPMT. “It’s a very constructive experience to be involved in the project from an early stage, and it has been critical in the planning of many details for our client” said Minka St. James, Contract Manager from Schmidbauer. The illustration, from Joel Bauer, National Renewable Energy Laboratory, shows three possible designs for floating wind turbines.
This is the fifth of Mammoet’s competitions, organised together with Offshore Wind Innovators and TKI Wind op Zee. It is focussing on safe and efficient transfer of objects from a floating vessel to offshore wind structures avoiding, if possible, using large installation vessels. Positioning of the supply vessel, and transferring the load first to the structure and then to
the nacelle are relevant. The deadline for preliminary
expressions of interest is 27th January. For more information, and to enter, please visit www.
offshorewindinnovators.nl/ products/5th-innovation- challenge. Cranes Today would of course be delighted should one of our readers become a finalist.
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