WO2019001660A1

WO2019001660A1 - Handling a wind turbine blade using an airship

Info

Publication number: WO2019001660A1
Application number: PCT/DK2018/050150
Authority: WO
Inventors: Gerner Larsen; Ivar J.B.K. JENSEN; Gunnar K. Storgaard Pedersen; Torben Ladegaard Baun; André Heath HARLEY
Original assignee: Vestas Wind Systems A/S
Priority date: 2017-06-30
Filing date: 2018-06-20
Publication date: 2019-01-03

Abstract

The invention provides a method for handling a wind turbine blade using an airship (2), comprising arranging the blade (101) at least partly inside the airship (2), such that a longitudinal axis (BLA) of the blade (101) is substantially parallel to a longitudinal axis (ALA) of the airship (2).

Description

HANDLING A WIND TURBINE BLADE USING AN AIRSHIP

TECHNICAL FIELD

The present invention relates to a method for handling a wind turbine blade using an airship, and to an airship.

BACKGROUND OF THE INVENTION

A horizontal axis wind turbine is known to have an electric generator in a nacelle on top of a tower, where a rotor with a substantially horizontal axis mounted to the nacelle and arranged to drive the generator. The nacelle is usually arranged to be rotated in relation to the tower, to point the rotor towards the wind.

With growing sizes of horizontal axis wind turbines, challenges in handling of components, such as blades, increase. The transport of such components entail large road transport arrangements. Installation, service and repair often require the use of large cranes, which require a time consuming and costly crane transport and crane assembly procedure.

The use of airships has been suggested to facilitate handling of wind turbine components, WO2010145665 discloses the use of an airship to transport a wind turbine component.

WO2010145666 discloses docking and connecting an airship to a wind turbine, and unloading a wind turbine component from the airship to the wind turbine, or loading a wind turbine component from the wind turbine to the airship.

Although the use of airships provides advantages, there is still a desire to improve conditions for handling wind turbine components. For example, when transported by an airship, a large wind turbine component may, due to its exposure to the surrounding air flow, transfer significant forces to the airship, resulting an increased airship fuel consumption, and/or in difficulties in the manoeuvring of the airship. Further, weather conditions may limit the use of known handling procedures, e.g. with airships. Wind, precipitation, coldness and heat may contribute to obstruct wind turbine installation, service or repair, or at least make it difficult. SUMMARY OF THE INVENTION

It is an object of the present invention to facilitate the handling of components for horizontal axis wind turbines. It is also an object of the invention to facilitate installation, service and/or repair of horizontal axis wind turbines.

The objects are reached with a method for handling a wind turbine blade using an airship, the method comprising arranging the blade at least partly inside the airship, such that a longitudinal axis of the blade is substantially parallel to a longitudinal axis of the airship.

A horizontal wind turbine blade may be slender in shape. Such a blade may extend from a root end of the blade to a tip end of the blade. Regardless whether the blade is straight, or presents a bend in an unloaded condition, the longitudinal axis of the bl ade may intersect the root end as well as the tip end.

An airship may have an elongated shape. The longitudinal axis of the airship may extend along a major extension of the airship. The longitudinal axis of the airship may be parallel with an intended direction of travel of the airship.

The blade longitudinal axis being substantially parallel to the airship longitudinal axis, is understood as the blade longitudinal axis being parallel to the airship longitudinal axis, or presenting in relation to the airship longitudinal axis a minor, or non-essential, non-zero angle.

Arranging the blade at least partly inside the airship, such that a longitudinal axis of the blade is substantially parallel to a l ongitudinal axis of the airship, all ows for avoiding the blade being exposed to the external airflow during transportation. In addition, the parallel orientation allows for keeping the cross-flow area of the combination of the airship and the blade relatively small. Further, the airship shape is utilised in an advantageous manner so that a relatively long blade may be transported without creating a relatively large cross-section. Hence, the aerodynamic drag of the blade transporting airship may be kept low. This provides for decreasing the airship fuel consumption. The invention may also facilitate the

manoeuvring of the airship. Arranging the blade at least partly inside the airship the makes it possible for service staff to perform maintenance and repair of the blade in a space enclosed by the airship. The space enclosed by the airship may be sheltered from wind, precipitation, coldness and/or heat. Thereby, a safe and controlled environment may be provided for such maintenance and repair actions.

Preferably, the method further comprises introducing the blade through a front section of the airship and in a direction towards a rear section of the airship. During the introduction the blade may be maintained substantially parallel to the airship longitudinal axis. The method may comprise introducing the blade through a rear section of the airship and in a direction towards the front section of the airship. During the introduction, the blade may be maintained substantially parallel to the airship longitudinal axis.

It is understood that the longitudinal axis of the airship may intersect the airship front and rear sections. By such an introduction of the blade through the front or rear section, a minimal adaption of the airship staicture may be needed for engaging the airship with the blade. For example, the airship may simply present an opening in the front or rear section. Bulkheads of an airship structural skeleton may be kept closed. Bulkheads of an airship structural skeleton may follow the entire periphery of an airship cross-section. If the airship is instead arranged to receive the blade by the latter being moved in a lateral direction of the airship, e.g. from underneath, the airship bulkheads may need to be open to allow the introduction of the blade, which is less beneficial from an airship structural point of view. By an introduction of the blade through the front or rear section, the airship may be kept structurally optimised. This may allow a larger payload. This may facilitate the handling of wind turbine components.

It should be noted that the introduction of the blade through the airship front or rear section involves a relative movement between the airship and the blade. In some implementations of the method, the airship may be fixed while the blade is moved into the airship. In other implementations, the blade may be fixed, while the airship is moved to enclose the blade.

Preferably, where the blade comprises a root end and a tip end, the introduction of the blade is done with the tip end first. Thereby, the root end may be, at the end of the blade introduction step, exposed to the airship exterior. The root end being exposed to the airship exterior may allow the engagement of the root end with a wind turbine rotor hub, while the blade is arranged at least partly inside the airship. Preferably said tip end is received fully within said airship. This will allow access to the tip inside the airship, e.g. for service or repair thereof. Such maintenance may include work on a lightning protection device at the blade tip.

Preferably, where the airship presents an opening at a front section of the airship or at a rear section of the airship, and the blade comprises a root end and a tip end, the root end may be located closer to the opening than the tip end. As suggested, thereby the root end may be exposed to the airship exterior. The root end being exposed to the airship exterior may allow the engagement of the root end with a wind turbine rotor hub, while the blade is arranged at least partly inside the airship.

In some embodiments, the blade is entirely enclosed by the airship during transport of the blade by means of the airship. Thereby, said benefi cial reduction of the aerodynamic drag may be further secured.

Preferably, the method comprises the step of removing the blade from, or installing the blade on, a rotor hub of a wind turbine. During such an installation, the blade may be at least partly located inside the airship. Thereby, the blade removal procedure, or the blade installation procedure, may be performed with the airship at least partly enclosing the blade. The enclosure will provide a compaction of the blade and airship assembly. Such a compaction will reduce the sensitivity to wind gusts during the blade removal or installation.

Preferably, the method comprises the step of performing maintenance and/or repair of the blade, while the blade is at least partly located inside the airship. As suggested, thereby, a safe and controlled environment may be provided for such maintenance and repair actions.

In some embodiments, the blade maintenance and/or repair is performed while the blade is mounted to a rotor hub of a wind turbine. Thereby the airship may provide the function of a workshop for the blade while the blade is installed on the wind turbine. Such a function may remove cost of dismounting and transporting blade for repair.

The blade may be a horizontal axis wind turbine blade. The blade may be part of a horizontal axis wind turbine. The wind turbine may comprise a tower, a nacelle, and a rotor hub. The hub may be rotatably mounted to the nacelle. The nacelle may be mounted to the tower such that the nacelle may be rotated in relation to the tower around a substantially vertical axis. The blade may extend between a root end and a tip end thereof. The method may further comprise: determining a wind direction, rotating the hub in relation to the nacelle, and rotating the nacelle in relation to the tower, so that a blade-mounting face of the hub is facing downwind. The blade may be moved by means of the airship, while the longitudinal axis of the bl ade is substantially parallel to the longitudinal axis of the airship, to bring the blade root end towards the blade-mounting face of the hub.

Thereby, the airship longitudinal axis may be aligned with the wind while docking the blade root end to the hub. Thereby, lateral wind forces may be avoided. Thereby, tendencies of the airship to move the root end off-centre during the docking procedure, may be avoided.

Said blade may be a horizontal axis wind turbine blade. Said blade may be part of a horizontal axis wind turbine. Said wind turbine may comprise a rotor hub. Said blade may extend between a root end and a tip end thereof. The method may further comprise attaching a line, such as a rope or a wire, to the blade root end. The blade may be moved by means of the airship to bring the blade root end in a vicinity of the hub. A portion of said line may be engaged at said hub. A docking of said blade root end to said hub may be controlled by means of said line.

Engaging a portion of said line may be done with or without a tool, e.g. something similar to a boathook. Thereby, the blade, apart from the root end thereof, may be enclosed by the airship while the airship approaches the hub. The line may provide means for minor adjustments in the docking procedure. The docking procedure may involve mating a large number of threaded pins to holes distributed along a blade-mounting face of the hub. wherein some embodiments, said blade may be mounted so as to extend from a rotor hub of a horizontal axis wind turbine comprising a tower and a nacelle. The hub may be rotatably mounted to the nacelle. The nacelle may be mounted to the tower such that the nacelle may be rotated in relation to the tower around a substantially vertical axis. The method may comprise determining a wind direction, rotating the hub in relation to the nacelle, and rotating the nacelle in relation to the tower, so that the blade is substantially horizontal and extends from the hub in a downwind direction. The method may further include moving the airship towards the wind turbine so as to introduce the blade at a front section of the airship and in a direction towards a rear section of the airship, or at the rear section of the airship and in a direction towards the front section of the airship, thereby to provide said arrangement of said blade wherein the longitudinal axis of the blade is substantially parallel to the airship longitudinal axis and with the blade being at least partly located inside the airship.

Thereby, during a blade removal and/or blade service procedure, the airship longitudinal axis may be aligned with the wind while moving the airship towards the wind turbine so as to introduce the blade into the airship. Thereby, lateral wind forces may be avoided. Thereby, tendencies of the airship to move laterally in relation to the blade, may be avoided.

In some embodiments, a gas having a density lower than air, such as helium, is present in a cavity of the blade, while the blade is at least partly located inside the airship. Thereby, the effective payload presented by the blade may be decreased during transportation by means of the airship. Preferably, the gas is introduced to the blade cavity before arranging the blade so as to be at least partly located inside the airship. This may involve sealing the blade after the gas introduction. Thereby, a procedure of loading or unloading the blade from the airship maybe facilitated, since the weight of the blade is reduced.

The objects are also reached with a method comprising mounting a first wind turbine component to a second wind turbine component, while supporting the first component by- means of an airship, wherein the first component is, when mounted to the second component, at least partly located inside the airship. The first component may be a wind turbine blade, preferably a horizontal axis wind turbine blade. The second component may be a wind turbine rotor hub. Said hub may be located at a nacelle atop a tower. Alternatives are possible. The first component may be a hub. The second component may be a main shaft in a nacelle. The first component may be a nacelle. The second component may be a tower. The first component may be a tower section. The second component may be a further tower section. The second component may be a foundation for a wind turbine.

The first component being, when mounted to the second component, at least partly located inside the airship, allows for avoiding that the first component is exposed to wind gusts when mounted. A reduced exposure of the airship to wind gusts facilitates the manoeuvring of the airship. The objects are also reached with a method for handling a horizontal axis wind turbine blade, the method comprising performing maintenance and/or repair operations on the blade, while said blade is at least partly located inside an airship. As suggested, thereby, a safe and controlled environment may be provided for such maintenance and repair actions.

The objects are also reached with a method for installing a blade of a horizontal axis wind turbine, said turbine comprising a tower, a nacelle, and a rotor hub, the hub being rotatably mounted to the nacelle, and the nacelle being mounted to the tower such that the nacelle maybe rotated in relation to the tower around a substantially vertical axis, wherein said blade extends between a root end and a tip end thereof, said method comprising determining a wind direction, rotating the hub in relation to the nacelle, and rotating the nacelle in relation to the tower, so that a blade-mounting face of the hub is facing downwind, and moving the blade by means of an airship, while a longitudinal axis of the blade is substantially parallel to a longitudinal axis of the airship, to bring the blade root end towards the blade-mounting face of the hub. Thereby, as also suggested above, the airship may be aligned with the wind while docking the blade root end to the hub. Thereby, lateral wind forces may be reduced or avoided. Thereby, tendencies of the airship to move the root end off-centre during the docking procedure, may be avoided.

The objects are also reached with a method for installing a blade of a horizontal axis wind turbine comprising a rotor hub, the blade extending between a root end and a tip end thereof, the method comprising attaching a line to the blade root end, moving the blade by means of an airship to bring the blade root end in a vicinity of the hub, engaging a portion of said line at said hub, and controlling a docking of the blade root end to the hub by means of the line. As suggested, thereby, the line may provide means for advantageous minor adjustments in the docking procedure.

The objects are also reached with a method for repair and/or maintenance of a horizontal axis wind turbine, the wind turbine comprising a blade mounted so as to extend from a rotor hub of the wind turbine, the wind turbine further comprising a tower and a nacelle, the hub being rotatably mounted to the nacelle, and the nacelle being mounted to the tower such that the nacelle may be rotated in relation to the tower around a substantially vertical axis, said method comprising determining a wind direction, rotating the hub in relation to the nacelle, and rotating the nacelle in relation to the tower, so that the blade is substantially horizontal and extends from the hub in a downwind direction, moving an airship towards the wind turbine such that a longitudinal axis of the airship is substantially parallel to a longitudinal axis of the blade, and engaging the blade with the airship.

As suggested, thereby, during a blade removal and/or blade service procedure, the airship longitudinal axis may be aligned with the wind while moving the airship towards the wind turbine so as to engage the blade with the airship. Thereby, lateral wind forces, tending to move the airship laterally in relation to the blade, may be avoided.

The object may also be reached by a method for handling a wind turbine blade, wherein a gas with less density than air, such as helium, is present in a cavity of the blade, while

transporting the blade by means of a flying machine. Thereby, as suggested above, the weight of the blade may be reduced during the transportation.

The object may also be reached with an airship, arranged to house, i.e. enclose, at least a portion of a wind turbine blade such that a longitudinal axis of the blade is substantially parallel to a longitudinal axis of the airship. Preferably, a front section of said airship presents an opening configured for introducing the blade into said airship in a direction towards a rear section of the airship. In some embodiments, a rear section of said airship presents an opening configured for introducing the blade into said airship in a direction towards the front section of the airship. As suggested above, thereby, the airship may be kept structurally optimised- Thereby, a larger payload may be allowed. Thereby, the handling of wind turbine components may be facilitated.

Preferably, the airship comprises a workshop for maintenance and/or repair of the blade. As suggested, thereby, a safe and controlled environment may be provided for such maintenance and repair actions.

The object may also be reached with an airship arranged to house at least a portion of a wind turbine component, wherein the airship comprises a workshop for maintenance and/or repair of the component. The component may be a horizontal axis wind turbine blade. The airship may be arranged to house the blade such that a longitudinal axis of the blade is substantially parallel to a longitudinal axis of the airship. BRIEF DESCRIPTION OF THE DRAWINGS

Below, embodiments of the invention will be described with reference to the drawings, in which

fig. I depicts a context of a method according to an embodiment of the invention, fig. 2 is a diagram depicting steps in the method, the context of which is shown in fig. 1,

fig. 3 depicts a context of a method according to a further embodiment of the invention, and

fig. 4 is a diagram depicting steps in the method, the context of which is shown in fig. 3.

DETAILED DESCRIPTION OF EMBODIMENTS

With reference to fi g. 1 and fig. 2, a method, according to an embodiment of the invention, for handling a blade for a horizontal axis wind turbine will be described.

The wind turbine 1 in this example comprises a tower 104, a nacelle 103, and a rotor hub 102. The hub 102 is rotatabiy mounted to the nacelle 103 for driving an electric generator (not shown) of a dnvetrain (not shown) in the nacelle. During blade installation and service procedures, the hub 102 may be rotated by means of one or more auxiliary electric motors (not shown) engaged with the drivetrain. The nacelle 103 may be mounted to the tower 104. The nacelle 103 may be mounted to the tower 104 such that the nacelle 103 may be rotated in relation to the tower 104 around a substantially vertical axis. Such a rotation of the nacelle may be effected by means of one or more yaw drives.

The method in this example comprises installing the blade 101 on the rotor hub 102, while the blade is partly located inside the airship 2. The airship 2 may present an opening 211 at a front section 201 of the airship 2. The blade 101 may extend between a root end 111 and a tip end 112 thereof. While transported to the wind turbine 1 by means of the airship 2, a longitudinal axis BLA of the blade 101 may be substantially parallel to a longitudinal axis ALA of the airship 2. The blade 101, except the root end 111 thereof, may be entirely enclosed by the airship 2. The root end may protrude from the opening 21 1. The method comprises determining S I a wind direction WD. Determining S I a wind direction WD may he done by any suitable wind instrument, e.g. mounted on the nacelle 03. The hub 102 is rotated in relation to the nacelle 103, and/or the nacelle 103 is rotated in relation to the tower 104, so that a blade-mounting face 121 of the hub 102 is facing downwind S2.

The method may further comprise attaching S3 a line 221, in the form of a rope or a wire, to the blade root end 111. The blade 101 may be moved by means of the airship 2, to bring the blade root end 11 1 towards the blade-mounting face 121 of the hub 102. Thereby, the blade root end 11 may be brought S4 into a vicinity of the hub 102. A person (not shown) in the hub may use a tool in the form of a pole 222 with a hook at one end, similar to a boathook, to engage S5 a portion of the line 221 . The docking of the blade root end 1 1 to the hub 102 may be controlled S6 by means of the line 221. It should be noted however that alternative manners of docking of the blade root end 1 1 1 to the hub 102 are possibl e. For example, docking of the blade root end 111 to the hub 102 could be done exclusively by manoeuvring the airship 2.

Upon securing S7 the blade to the hub, the airship 2 is moved S8 away from the hub 102. The movement S8 of the airship 2 away from the hub 102, may be a movement along the longitudinal axis BLA of the blade 101. By the movement S8, the airship 2 may be released from the blade 101 .

With reference to fig. 3 and fig. 4, a method, according to a further embodiment of the invention, for handling a blade for a horizontal axis wind turbine will be described. The wind turbine I , and the airship 2 may be the same as in the method described with reference to fig. 1 and fig. 2. The method in this example comprises removing the blade 101 from the rotor hub 102 of the wind turbine 1.

The method may comprise determining SlOl a wind direction WD. The method may further comprise rotating the hub 102 in relation to the nacelle 103, and/or rotating the nacelle 103 in relation to the tower 104, so that the blade 101 is substantially horizontal and extends S I 02 from the hub 102 in a downwi d direction WD.

The method further includes moving SI 03 the airship 2 towards the wind turbine 1 so as to introduce the blade 101 through the opening 21 1 at the front section 201 of the airship 2. Thereby, the blade 101 may be introduced in a direction towards a rear section 202 of the airship 2, The introduction of the blade 101 may be done with the tip end 1 12 first. With the introduction, the blade may become partly located inside the airship 2. With the introduction, the blade may become substantially parallel to the airship longitudinal axis ALA.

The root end 111 may be located externally of the airship. The root end 1 1 1 may be located closer to the opening 21 than the tip end 1 12. The tip end 112 may be kept inside the airship 2,.

Thereupon, the blade 101 may be released SI 04 from the hub 102. Thereupon, the airship 2, carrying the blade 101, may be moved away from the wind turbine, e.g. towards a blade service facility.

In some embodiments, the blade 101 may be kept secured to the hub 102, while partly enclosed by the airship 2. Thereby, the airship may comprise a workshop for maintenance and/or repair of the blade 101, while the blade 101 is partly located inside the airship 2.

As will be understood by those skilled in the present field of art, numerous changes and modifications may be made to the above d escribed and other embodiments of the present invention, without departing from its scope as defined in the appending claims.

Claims

1. A method for handling a wind turbine blade using an airship (2), characterised by arranging the blade (101) at least partly inside the airship (2), such that a longitudinal axis (BLA) of the blade (101) is substantially parallel to a longitudinal axis (ALA) of the airship (2).

2. A method according to claim 1, further comprising introducing the blade (101) through a front section (201 ) of the airship (2) and in a direction towards a rear section (202) of the airship (2), while maintaining the blade (101) substantially parallel to the airship longitudinal axis (ALA), or introducing the blade (101) through a rear section (202) of the airship (2) and in a direction towards the front section (201) of the airship (2), while maintaining the blade (101) substantially parallel to the airship longitudinal axis (ALA).

3. A method according to claim 2, wherein the blade (101) comprises a root end (11 1) and a tip end (112), wherein the introduction of the blade (101) is done with the tip end (112) first, preferably wherein said tip end (112) is received fully within said airship (2).

4. A method according to any one of the preceding claims, wherein the airship (2) presents an opening (211) at a front section (201 ) of the airship (2) or at a rear section (202) of the airship (2), and the blade (101) comprises a root end (111) and a tip end

( 1 12), the root end ( 1 1 1 ) being located closer to the opening (21 1) than the tip end (1 12).

5. A method according to any one of the preceding claims, wherein the blade (101) is entirely enclosed by the airship (2) during transport of the blade (101) by means of the airship (2),

6. A method according to any one of the preceding claims, comprising the step of removing the blade (101) from, or installing the blade (101) on, a rotor hub (102) of a wind turbine (1), while the blade is at least partly located inside the airship (2).

7. A method according to any one of the preceding claims, comprising the step of performing maintenance and/or repair of the blade ( 101), while the blade (101) is at least partly located inside the airship (2).

8. A method according to claim 7, wherein the blade maintenance and/or repair is performed while the blade (101) is mounted to a rotor hub (102) of a wind turbine (1).

9. A method according to any one of the preceding claims, said blade (101) being a horizontal axis wind turbine blade (101), said blade (101) being part, of a horizontal axis wind turbine (1), said wind turbine (1) comprising a tower (104), a nacelle ( 103), and a rotor hub (102), the hub (102) being rotatabiy mounted to the nacelle (103), and the nacelle (103) being mounted to the tower (104) such that the nacelle ( 103) may be rotated in relation to the tower (104) around a substantially vertical axis, the blade (101) extending between a root end (111) and a tip end (1 12) thereof, the method further comprising: determining a wind direction (WD), rotating the hub (102) in relation to the nacelle (103), and rotating the nacelle (103) in relation to the tower (104), so that a blade- mounting face (121) of the hub (102) is facing downwind, and moving the blade (101) by means of the airship (2), while the longitudinal axis (BLA) of the blade (101) is substantially parallel to the longitudinal axis (ALA) of the airship (2), to bring the blade root end (1 1 1) towards the blade-mounting face (121) of the hub (102).

10. A method according to any one of the preceding claims, said blade (101) being a horizontal axis wind turbine blade (101 ), said blade (101) being part of a horizontal axis wind turbine (1), said wind turbine (1) comprising a rotor hub (102), said blade (101) extending between a root end (1 1 1 ) and a tip end (112) thereof, the method further comprising attaching a line (221) to the blade root end (111), moving the blade (101) by means of the airship (2) to bring the blade root end (1 1 1) in a vicinity of the hub (102), engaging a portion of said line (221) at said hub (102) and controlling a docking of said blade root end (1 11) to said hub (102) by means of said line (221).

11. A method according to any one of the preceding claims, where said blade (101) is mounted so as to extend from a rotor hub (102) of a horizontal axis wind turbine (1) comprising a tower (104) and a nacelle (103), the hub (102) being rotatabiy mounted to the nacelle (103), and the nacelle (103) being mounted to the tower (104) such that the nacelle (103) may be rotated in relation to the tower (104) around a substantially vertical axis, the method comprising determining a wind direction (WD), rotating the hub (102) in relation to the nacelle (103), and rotating the nacelle (103) in relation to the tower (104), so that the blade (101) is substantially horizontal and extends from the hub (102) in a downwind direction (WD), said method further including moving the airship (2) towards the wind turbine (1) so as to introduce the blade (101) at a front section (201) of the airship (2) and in a direction towards a rear section (202) of the airship (2), or at the rear section (202) of the airship (2) and in a direction towards the front section (201) of the airship (2), thereby to provide said arrangement of said blade (101) wherein the longitudinal axis (BLA) of the blade (101 ) is substantially parallel to the airship longitudinal axis (ALA) and with the blade (101) being at least partly located inside the airship (2),

12. A method comprising mounting a first wind turbine component (101) to a second wind turbine component (102), while supporting the first component (101) by means of an airship (2), characterised in that the first component (101) is, when mounted to the second component (102), at least partly located inside the airship (2).

13. A method according to claim 12, where the first component is a wind turbine blade (101), and the second component is a wind turbine rotor hub (102), preferably wherein said hub is located at a nacelle atop a tower.

14. A method for handling a horizontal axis wind turbine blade (101), characterised by performing maintenance and/or repair operations on the blade (101), while said blade ( 101 ) is at least partly located inside an airship (2).

15. A method for installing a blade (101) of a horizontal axis wind turbine (1), said turbine comprising a tower (104), a nacelle (103), and a rotor hub (102), the hub (102) being rotatably mounted to the nacelle (103), and the nacelle (103) being mounted to the tower ( 104) such that the nacelle (103) may be rotated in relation to the tower (104) around a substantially vertical axis, wherein said blade (101) extends between a root end ( 1 1) and a tip end (112) thereof, said method being characterised by determining a wind direction (WD), rotating the hub (102) in relation to the nacelle (103), and rotating the nacelle (103) in relation to the tower (104), so that a blade-mounting face (121) of the hub (102) is facing downwind, and moving the blade (101) by means of an airship (2), while a longitudinal axis (BLA) of the blade (101 ) is substantially parallel to a longitudinal axis (ALA) of the airship (2), to bring the blade root end (111) toward s the blade-mounting face (121) of the hub (102),

16. A method for installing a blade (101) of a horizontal axis wind turbine (1) comprising a rotor hub (102), the blade (101) extending between a root end (111) and a tip end (112) thereof, the method comprising attaching a line (221) to the blade root end (1 1 1), moving the blade (101) by means of an airship (2) to bring the blade root end (1 11) in a vicinity of the hub (102), engaging a portion of said line (221) at said hub (102), and controlling a docking of the blade root end (11 1) to the hub (102) by means of the line (221).

17. A method for repair and/or maintenance of a horizontal axis wind turbine (1), the wind turbine comprising a blade (101) mounted so as to extend from a rotor hub (102) of the wind turbine (1), the wind turbine further comprising a tower (104) and a nacelle (103), the hub (102) being rotatably mounted to the nacelle (103), and the nacelle (103) being mounted to the tower (104) such that the nacelle (103) may be rotated in relation to the tower (104) around a substantially vertical axis, said method being characterised by determining a wind direction (WD), rotating the hub (102) in relation to the nacelle (103), and rotating the nacelle ( 103) in relation to the tower (104), so that the blade (101) is substantially horizontal and extends from the hub (102) in a downwind direction (WD), moving an airship (2) towards the wind turbine (1) such that a longitudinal axis (ALA) of the airship is substantially parallel to a longitudinal axis (BLA) of the blade (101), and engaging the blade (101) with the airship (2) .

18. An airship (2), characterized in that the airship is arranged to house at least a portion of a wind turbine blade (101) such that a longitudinal axis (BLA) of the blade (101) is substantially parallel to a longitudinal axis (ALA) of the airship (2).

19. An airship (2) according to claim 18, wherein a front section (201) of said airship (2) presents an opening (211) configured for introducing the blade (101) into said airship (2) in a direction towards a rear section (202) of the airship (2); and/or, wherein a rear section (202) of said airship (2) presents an opening configured for introducing the blade (101 ) into said airship (2) in a direction towards the front section (201) of the airship (2).

20. An airship (2) according to any one of claims 18-19, wherein the airship (2) comprises a workshop for maintenance and/or repair of the blade (101).

21. An airship (2) aixanged to house at least a portion of a wind turbine component (101), characterized in that the airship (2) comprises a workshop for maintenance and/or repair of the component.

22. An airship (2) according to claim 21, wherein the component is a horizontal axis wind turbine blade (101).

23. An airship (2) according to claim 22, wherein the airship is arranged to house the blade such that a longitudinal axis (BLA) of the blade (101) is substantially parallel to a longitudinal axis (ALA) of the airship.