Offshore wind turbine assembly vessel

1 . A vessel for assembling wind turbines and for installing the assembled wind turbine on a foundation, the vessel comprising:

a floating hull;

a wind turbine installation crane mounted on the floating hull;

a single main deck, wherein the single main deck is a wind turbine components storage deck, for storing components of a wind turbine; and

at least one wind turbine assembly station,

wherein the installation crane has at least one assembly side facing the at least one wind turbine assembly station, and has an installation side, and wherein the installation crane is configured to perform one or more wind turbine assembly steps,

wherein the main deck is provided with an upend track for supporting an upend cart, to enable upending of wind turbine masts or foundation piles, wherein, during the upending process, the upend cart supports the bottom end of the pile, or mast, while the top end of the pile, or mast, is lifted by the installation crane, and thus, the bottom end of the pile, or mast, is guided along the deck, over the tracks, towards the installation crane,

wherein the installation crane is provided with a wind turbine hoisting device having one or more wind turbine suspension elements, said wind turbine hoisting device being adapted to support and to raise and lower in a controllable manner an assembled wind turbine, the assembled wind turbine comprising a mast combined with the nacelle and the blades fitted,

wherein the installation crane has a base section and a top section, wherein the top section is rotatable supported by a bearing, and wherein the top section can be rotated with the wind turbine hoisting device relative to the base section about a vertical axis, and wherein the hoisting device can thus transfer at least an upper mast part between the assembly stations and the installation side,

wherein the installation crane is configured for arranging the assembled wind turbine from the at least one wind turbine assembly station into a mounting position, above a wind turbine foundation adjacent the vessel, at the installation side of the installation crane, for supporting an assembled wind turbine at the installation side in a mounting position above a foundation and for lowering the wind turbine onto the foundation.

2 . The vessel according to claim 1 , wherein, at the installation side of the crane, the main deck extends on opposite sides of the installation crane and, when the installation crane supports an assembled wind turbine above a foundation, the foundation is partially enclosed by the vessel on three sides.

3 . The vessel according to claim 1 , wherein the vessel comprises a catamaran like hull, with two main floaters extending along opposite sides of the vessel, and at the installation side of the crane, the hull extends at opposite sides of the installation crane, and wherein, when the installation crane supports an assembled wind turbine above a foundation, the foundation is partially enclosed by the hull of the vessel on three sides.

4 . The vessel according to claim 1 , wherein the upend track is located at a side of the installation crane opposite the installation side, and, when the vessel is at an installation location for mounting a wind turbine on a foundation, the installation crane is located between the upend track and the foundation.

5 . The vessel according to claim 1 , wherein the upend track and the installation crane are set up on a centre line of the vessel, and the upend track extends in a longitudinal direction of the vessel.

6 . The vessel according to claim 1 , wherein the at least one wind turbine assembly station is a first wind turbine assembly station, and wherein the vessel further comprises a second wind turbine assembly station, wherein the first assembly station is configured for supporting a mast in an upright installation position, wherein the second assembly station is configured for supporting the mast in an upright installation position with the nacelle in an installation position for mounting blades to the nacelle, and wherein the first wind turbine assembly station is located on a first side of the installation crane, the second assembly station is located on a second side of the installation crane.

7 . The vessel according to according to claim 6 , wherein the vessel further comprises a third wind turbine assembly station, and wherein the second and third wind turbine assembly station are located on opposite sides of the installation crane, and the first assembly station is located opposite a first vertical side of the wind turbine installation crane.

8 . The vessel according to claim 1 , wherein the vessel further comprises a blade handling apparatus for transferring a blade between a horizontal supply position and a fastening position adjacent the nacelle on top of a mast or an upper mast section.

9 . The vessel according to claim 1 , wherein the vessel comprises a foundation restraint system, the foundation restraint system being configured for engaging a floating foundation, and to reduce movement of the floating foundation relative to the vessel and/or monitor the movement of the floating foundation relative to the to the vessel.

10 . The vessel according to claim 1 , wherein the wind turbine installation crane is configured to actively compensate for sea-state induced movement of an assembled wind turbine relative to the foundation onto which the wind turbine is to be lowered.

11 . The vessel according to claim 1 , wherein the vessel furthermore comprises a mast-receiving well that is sunk into, or through, the hull, and wherein the mast-receiving well is configured to receive therein at least a portion of the mast of the wind turbine, such that the distance between the nacelle and the storage deck is reduced, to facilitate mounting blades to the nacelle.

12 . The vessel according to claim 1 , wherein the vessel comprises a nacelle support, the nacelle support being fixed to the deck of the vessel, such that a nacelle can be supported by the nacelle support at a distance above the deck to enable blades to be mounted to the nacelle.

13 . A method for assembling wind turbines on a wind turbine assembly vessel, using a wind turbine assembly vessel, wherein the wind turbine assembly vessel comprises:

a floating hull;

a foundation restraint system;

a wind turbine components storage deck, for storing components of a wind turbine;

at least one wind turbine assembly station; and

a wind turbine installation crane, mounted on the floating hull, wherein the wind turbine installation crane has at least one assembly side facing the at least one wind turbine assembly station, and has an installation side,

wherein the method comprises:

moving one or more wind turbine components from the wind turbine components storage deck to the at least one wind turbine assembly station;

engaging a floating foundation with the foundation restraint system;

reducing movement of the floating foundation relative to the vessel and/or monitoring the movement of the floating foundation relative to the vessel; and

using the installation crane to:

perform one or more assembly steps;

support the assembled wind turbine at the assembly side and arranging the assembled wind turbine from the assembly station into the mounting position, above a wind turbine foundation adjacent the vessel, at the installation side of the installation crane; and

lower the assembled wind turbine onto the foundation.

14 . The method according to claim 13 , wherein the method further comprises the wind turbine assembly step of lifting the nacelle and hoisting the nacelle on the mast or upper mast part, using the wind turbine installation crane, and mounting the nacelle on the mast or upper mast part.

15 . The method according to claim 13 , wherein the method further comprises the wind turbine assembly step of arranging the mast or the upper mast part, with the nacelle mounted thereupon, in an upright installation position with the nacelle in an installation position for mounting a blade to the nacelle.

16 . The method according to claim 13 , wherein the method further comprises a blade mounting process for mounting the blades to the nacelle, the blades mounting process comprising one or more of the steps of:

lifting a first blade into a fastening position adjacent the nacelle, mounting the first blade to the nacelle, and rotating the nacelle into a successive installation position;

lifting a second blade into a fastening position adjacent the nacelle, mounting the second blade to the nacelle, and rotating the nacelle into a successive installation position; and

lifting a third blade into a fastening position adjacent the nacelle, and mounting the third blade to the nacelle.

17 . The method according to claim 16 , wherein the nacelle is mounted on a nacelle support fixed to the deck of the vessel, such that the nacelle is supported by the nacelle support at a distance above the deck.

18 . The method according to claim 13 , wherein the method further comprises upending the mast or the upper mast part of the wind turbine from a horizontal storage position into the upright installation position, using the wind turbine installation crane.

19 . The method according to claim 13 , wherein the at least one wind turbine assembly station is a first wind turbine assembly station, located on a first side of the installation crane, the first side being opposite the installation side of the installation crane, and the vessel further comprises a second wind turbine assembly station, located on a second side of the installation crane,

wherein the first assembly station is used for up-ending a mast or a top section of the mast and/or for mounting the nacelle on the mast or the top section of the mast,

wherein the second assembly station is used for completing the assembly of the wind turbine using the installation crane, and/or for mounting the blades to the nacelle, and

wherein the installation crane is used for arranging the mast or top section of the mast from the first assembly station to the second assembly station, for arranging the assembled wind turbine from the second assembly station to the installation side of the installation crane, and for lowering the assembled wind turbine on the foundation.

20 . A method for assembling wind turbines on a wind turbine assembly vessel, using a wind turbine assembly vessel, wherein the wind turbine assembly vessel comprises:

a floating hull;

a wind turbine components storage deck, for storing components of a wind turbine, a lower mast part, an upper mast part, a rotor assembly;

at least one wind turbine assembly station; and

an installation crane, mounted on the floating hull, wherein the installation crane has at least one assembly side facing the at least one wind turbine assembly station, and has an installation side,

wherein the method comprises:

moving one or more wind turbine components from the wind turbine components storage deck to the at least one wind turbine assembly station;

a blade mounting process for mounting the blades to the nacelle, the blades mounting process comprising one or more of the steps of:

lifting a first blade into a fastening position adjacent the nacelle, mounting the first blade to the nacelle, and rotating the nacelle into a successive installation position;

lifting a second blade into a fastening position adjacent the nacelle, mounting the second blade to the nacelle, and rotating the nacelle into a successive installation position; and

lifting a third blade into a fastening position adjacent the nacelle, and mounting the third blade to the nacelle; and

using the installation crane to:

perform one or more assembly steps;

support the assembled wind turbine at the assembly side and arranging the assembled wind turbine from the assembly station into the mounting position, above a wind turbine foundation adjacent the vessel, at the installation side of the installation crane; and

lower the assembled wind turbine onto the foundation.