A hollow structural element of a wind energy plant, in particular an offshore wind energy plant which includes a hollow structural element, and a cable arrangement extending along the hollow structural element. A shading element is arranged on the hollow structural element at a distance from the cable arrangement.

Method of lifting a wind turbine part (58) at a wind turbine site (1, 2), the method includes: providing a lifting apparatus (60) and a wind turbine part (58) to be lifted; providing a shield (40); providing manipulation equipment (45) associated with said shield (40); and suspending said part (58) from said lifting apparatus (60); moving said part (58) by means of said lifting apparatus (68); the method further including holding said shield (40) proximate and upwind of said part (58) being lifted by means of said manipulation equipment (45). The shield (40) may be held proximate the part (58) being lifted such that it acts to reduce the ambient wind force incident on the part (58). Preferably the method may be implemented such that wind speed conditions (w) at the part (58) being lifted are lower than ambient wind conditions (W) at said site (1, 2). A kite-flying apparatus includes a power kite (40) and associated manipulation equipment (45), including cables (42, 44) at least one steering winch (28, 29), the winch being received in a winching module (26) including a ballast receiving fitment and a winch control system.

A method for loading equipment and/or personnel onto a platform mounted on the nacelle tower of an offshore wind farm is provided. This method enables loading of equipment onto a platform mounted on the nacelle tower or on the monopile or tripod or jacket foundation of an offshore wind turbine without needing to mount the construction during the loading operation.

A rotor assembly includes a rotor mast, a rotor and a pivot arrangement. The rotor mast is for rotatable attachment of the rotor assembly to a support structure for rotation of the rotor assembly relative to the support structure about a rotation axis. The rotor has two rotor blades extending in a virtual plane in a longitudinal direction. The two rotor blades are arranged to be propelled by air flow. The pivot arrangement defines a pivot axis. The rotor is pivotably connected to the rotor mast for pivoting the two rotor blades simultaneously relative to the rotor mast about the pivot axis. The longitudinal direction and a projection of said pivot axis in the virtual plane enclose a constant acute angle in the virtual plane. A windmill and a wind farm includes the rotor assembly with a capacity in the range of 15-50 MW/km.sup.2.

Method for stabilizing a jack-up platform unit, the unit including a hull, a plurality of legs which are extendible from and/or through the hull and which are arranged to support the platform unit during off-shore operations, and a jacking system arranged to move the legs between a transport position and an operational position, wherein the jacking system is also arranged to move the hull along the plurality of legs between a floating position and an operational position, the method comprising the steps of lowering the plurality of legs until the legs stand on or in the seabed, raising the hull substantially above the sea surface, temporarily applying a preloading on the plurality of legs, further raising the hull to an operational height above the sea surface.

Described is a device for providing a sizeable, slender object having a longitudinal direction into an underwater bottom from a deck of a vessel. The device includes a lifting means configured to take up the object at a lifting point thereof and position it on the underwater bottom; an upending tool connected to an edge of the vessel and configured to engage a first circumferential part of the object suspended from the lifting means and provide a pivot around which the object can be upended; and a gripping tool connected to an edge of the vessel and configured to engage a second circumferential part of the object suspended from the lifting means, whereby the first and second circumferential parts are optionally spaced apart in the longitudinal direction of the object. The gripping tool includes an actuator system configured to act on at least one of the upending tool and the gripping tool and control movements of at least one of the first and the second circumferential parts, relative to the vessel. A method using the device is also described.

Disclosed is a semi-submersible floater defining an operating state and a non-operating state, and including at least two outer columns, a central column for receiving a payload, and, for each outer column, a branch in the form of pontoon connecting the outer column to the central column and defining a branch axis oriented from the central column towards the outer column. Each branch is formed from a first portion and a second portion which extend successively along the corresponding branch axis, each one over at least 10% of the total extent of the branch, along the branch axis. In the operating state of the floater, the second portion of each branch is at least partially filled with a ballast material, and the first portion does not contain any ballast material.

The invention relates to a method of manufacturing a tower (2) for an offshore wind turbine as well as such a tower. The method comprises providing the tower, mounting a crane (5) to an outer surface of the tower, and transporting the tower to the installation site of the wind turbine after the mounting of the crane. The crane comprises a base part (6) fixedly mounted to the tower, and a crane arm (7) pivotally connected to the base part at a first end (8). The method may further comprise a step of testing and certifying the crane according to a predetermined standard before the step of transporting the tower to the installation site. By application of the invention, the amount of installation work to be performed at the installation site can be minimized. In some embodiments of the invention, the crane arm has a shape matching the outer surface of the tower.

A system for placing a wind turbine assembly on a support surface of a support structure being supported on a seabed with a lifting crane provided on a floating vessel, said system can be changed from a first operation mode into a second operation mode to compensate a vertical reciprocal crane movement of the crane relative to the support structure.

A disconnectable mooring system for offshore semi-submersible floating structures. A disconnectable buoy has a number of mooring lines which include a buoy chain between the mooring chain and the buoy. The mooring chain and the buoy chain are connected via a three way mooring connector, with the third connection configured to pull the mooring connector to a mooring point on the structure. In a first configuration the buoy is disconnected and supports the mooring chains for recovery at shallow depths to be pulled in. In a second configuration, the mooring lines are pulled in via the mooring connectors thereby providing a spread mooring to the structure with the buoy chain left as a catenary between the buoy and mooring point.