Floating functional unit having one or more buoyancy bodies

Abstract

The invention relates to a floating functional unit, in particular a floating platform (1) or a watercraft, comprising a deck structure (2) and one or more buoyancy bodies (3a, 3b, 3c, 3d), one or more of the buoyancy bodies each comprising a rotor blade (4) or a part, in particular a longitudinal portion, of a rotor blade of a wind turbine. The invention further relates to such a buoyancy body and to a method for the production thereof from a rotor blade.

Description

[0001] Fraunhofer Society...eV

[0002] P149093PC00

[0003] Floating functional unit with one or more buoyancy bodies

[0004] The invention lies in the field of mechanics and plastics processing and is particularly advantageous in the manufacture of swimming platform molds.

[0005] Floating platforms and watercraft with buoyancy aids have been known for a long time. While watercraft can inherently act as buoyancy aids themselves, it is also known to equip platforms, means of transport, and other objects with separate buoyancy aids to make them float. Rafts and pontoon bridges are further examples of the use of buoyancy aids.

[0006] Larger platforms often require large buoyancy volumes, so large hollow bodies, made of metal or plastic, are frequently used as buoyancy aids. These large volumes, along with the need for mechanical stability and impact resistance, result in considerable costs.

[0007] The internet article https: / / saxony5.de.nachlese / rotorblatt-recycling.html (Katrin Hase: “From rotating rotor blade to floating platform” from June 26, 2024) states that it is generally known that parts of rotor blades from wind turbines can be used as floating bases for photovoltaic systems on lakes.

[0008] From the publication DE 25 33 913 Al it is known to cast floating bodies from concrete in order to create the lowest possible center of gravity for floating jetties.

[0009] From the publication DE 102014 110089 Al it is known to connect a floating platform with additional floats that float independently of the platform in its vicinity.

[0010] Welded metal hollow bodies are known as modular floating bodies from the publication DE 202019 004958 Ul.

[0011] Against this background, the present invention aims to provide inexpensive and durable buoyancy bodies in a simple manner and to enable the construction of simple, cost-effective, stable floating functional units.

[0012] The problem is solved with a floating functional unit and with buoyancy bodies according to the independent patent claims, as well as with a method for manufacturing buoyancy bodies.

[0013] The dependent patent claims present possible embodiments of the invention.

[0014] The invention thus relates in particular to a floating functional unit, especially a floating platform or watercraft, with several buoyancy bodies and a deck structure with a deck arranged over the buoyancy bodies, in which several of the buoyancy bodies each have a rotor blade or a part, in particular a longitudinal section of a rotor blade of a wind turbine, wherein the buoyancy bodies are cut and arranged in such a way that

[0015] -that, viewed from the center of gravity of the functional unit, in at least one, in particular in every, horizontal direction at least 50%, in particular at least 55% or 60% or even at least 80% of the buoyancy volumes have a distance from the center of gravity in the horizontal direction that is at least 70% of the distance of the outer edge of the deck structure from the center of gravity in the same direction, or

[0016] -that more than 75%, in particular more than 80% or more than 85%, of the buoyancy volumes are arranged outside a horizontal circle around the center of gravity of the functional unit with a diameter equal to half the mean of the largest and smallest horizontal dimensions of the functional unit.

[0017] Additionally, along an axis, more than 70% of the buoyancy volumes can have a distance from the center of gravity in the horizontal direction that is at least 70% of the distance of the outer edge of the deck structure from the center of gravity in the same direction.

[0018] In a special case, the lift bodies can also be formed entirely by a rotor blade or a part, in particular a longitudinal section, of a rotor blade of a wind turbine. The functional unit can have several separate, and in particular spaced-apart, lift bodies. Several or all of the lift bodies can each have their own outer skin, which is at least partially formed by the outer skin of a rotor blade of a wind turbine.

[0019] The deck above the buoyancy chambers can be a single, shared deck covering several of the buoyancy chambers. It can be a rigid structure accessible to people. The buoyancy chambers can be rigidly connected to each other, at least in groups, or flexibly connected to each other.

[0020] Such a floating functional unit combines a simple design with readily available and easily processed buoyancy bodies with the ecologically sound reuse or recycling of wind turbine rotor blades. Due to their high dynamic loads and stringent safety requirements, wind turbine rotor blades have a limited service life and must be regularly inspected and decommissioned after a few years. Because of the size of these rotor blades, which can be over 50 meters long, several meters wide at the root, and correspondingly thick, a large quantity of plastic material is generated, which must be disposed of in an environmentally sound manner. On the other hand, buoyancy bodies for floating platforms are manufactured using a high volume of plastic.If decommissioned rotor blades can be reused effectively, this offers not only a cost advantage but also a significant environmental benefit, as it saves material needed for manufacturing lift bodies. Furthermore, there is often a logistical advantage if, for example, rotor blades can be refurbished and reused near the wind turbine site, which is often offshore.

[0021] Wind turbine rotor blades are often not only very long, allowing for the construction of very large lift bodies, but also have a cross-sectional area that increases or decreases along their length. This allows for the creation of various types of lift bodies from longitudinal sections of the rotor blades, depending on the requirements. In terms of the weight-to-volume ratio, rotor blades are subject to similar requirements as lift bodies. A specific volume must be enclosed with the lowest possible weight and high mechanical strength. It is often advantageous to use only, or predominantly, those volume ranges of rotor blades as lift bodies for which the expected lift is greater than their own weight.Due to the described distribution of the buoyancy volumes in the horizontal direction within the functional unit, sufficient tilting stability can still be achieved for the unit itself and especially also under the expected additional loads on the functional unit.

[0022] This arrangement can be easily implemented using rotor blades or longitudinal sections of rotor blades, since these already have a cross-section that varies along their length, and the lift forces vary considerably in the horizontal direction, at least when the lift elements are arranged horizontally. Therefore, in many cases, the invention can be realized simply by appropriately aligning the lift elements. An advantageous embodiment of a floating functional unit can, for example, provide that several or all of the lift elements, with their longitudinal axes running parallel to the longitudinal axis of the rotor blade within the blade, are arranged parallel to each other, advantageously such that, in addition to the required lift, sufficient tilting stability of the functional unit is also ensured.It can be designed so that the center of gravity of the functional unit lies vertically below the point of application of the total lift. This is often difficult to achieve with floating platforms. Furthermore, it can be designed so that, as far out radially as possible from the center of gravity of the functional unit, the majority of the lift forces act as far out as possible in all directions. Due to the varying cross-section of rotor blades along their length, this is particularly easy to achieve through a suitable arrangement and orientation of the rotor blades or rotor blade sections within the functional unit.

[0023] This arrangement allows the use of several long buoyancy bodies, which can be accommodated in a confined space within the functional unit and thus generate significant buoyancy forces. This enables a floating functional unit to carry heavy loads.

[0024] Another advantageous embodiment may provide that the functional unit has a longitudinal axis and that rotor blades or segments of rotor blades of the same shape are arranged symmetrically, in particular mirror-symmetrically or point-symmetrically, to each other on both sides of the longitudinal axis.

[0025] With such an arrangement of the buoyancy bodies, the buoyancy forces can be distributed evenly, so that a tilting of the floating functional unit under load can be avoided.

[0026] In one embodiment, it may also be provided that buoyancy bodies are arranged directly along at least two opposing outer boundary edges of the functional unit and / or at four corners of the functional unit, the centers of mass of which are lower than the centers of mass of the buoyancy bodies arranged between them.

[0027] If such buoyancy bodies are arranged on the outer surfaces of the floating functional unit, they are the first buoyancy bodies to enter the water under an asymmetrical load. Due to their low volume, even a slight tilt generates a counterforce that counteracts the tilting of the floating functional unit. Under a high overall load on the functional unit, the remaining buoyancy bodies located between the outer ones also exert additional forces.

[0028] Another advantageous embodiment may provide that the buoyancy bodies arranged along the outer boundary edges of the functional unit have a larger volume than the buoyancy bodies arranged between them.

[0029] This embodiment ensures that the magnitude of the buoyancy forces developed by the buoyancy bodies arranged along the outer boundary edges of the functional unit is sufficient to counteract any asymmetrical weight loads occurring on the floating functional unit.

[0030] Furthermore, it may be provided that several or all lift bodies are arranged in a star shape with respect to their longitudinal axes, which run parallel to the longitudinal axis of the rotor blade within the rotor blade, wherein, in particular, in the case of a cross-sectional area that varies along the longitudinal axes of the lift bodies, the area with the largest cross-sectional area points radially outwards.

[0031] This arrangement of the buoyancy elements exhibits a particularly high degree of symmetry and effectively counteracts any asymmetrical weight loads that may occur. The use of larger cross-sections for the buoyancy elements, especially in the radially outer region, results in exceptionally high stability.

[0032] Another advantageous embodiment may provide that several lift bodies are connected to each other by spar straps or parts of spar straps of rotor blades.

[0033] In this way, the spar caps of rotor blades can also be reused as additional components. These are typically fiber-reinforced in the longitudinal direction, making them extremely tensile-resistant. They can thus hold together a floating functional unit with great stability. Furthermore, it is possible to connect several lift bodies to each other using plates cut from the skin of a rotor blade in the area behind the spar.

[0034] This allows parts of the shell to be reused as additional components of rotor blades. In the area behind the spar, viewed from the leading edge of the rotor blade, many rotor blades have flat, plate-like sections of the shell along a large portion of their length. These sections can be used to form a deck area for stabilizing a floating functional unit. In this area, the rotor blades are typically relatively thin, making it less suitable for forming lift-generating elements than the area near the leading edge.

[0035] Another advantageous embodiment may provide that each of the buoyancy bodies is sealed liquid-tight with bulkheads at one or both ends, wherein one or more buoyancy bodies in particular have one or more bulkheads for dividing their total volume into compartments separated from each other.

[0036] When longitudinal sections are cut out of a rotor blade, it is often necessary to seal these sections at their ends due to their hollow construction. This can be achieved by gluing in bulkheads, which can also be cut from plate-shaped segments of a rotor blade. To separate areas of the lift elements in the event of a leak, it can be advantageous to divide the total volume of a single lift element with such bulkheads. In many cases, the end bulkheads and the partitions used for this purpose can run essentially perpendicular to the longitudinal axis of the respective lift element. However, in some cases, due to the required mechanical stability, it can also be advantageous for the bulkheads to form an angle with the respective longitudinal axis that is less than 90 degrees, and in particular less than 80 degrees.

[0037] Furthermore, it may be provided that an air bag and / or foam filling is included within at least one of the buoyancy bodies. This measure serves to further ensure the buoyancy of the buoyancy bodies in the event of a leak.

[0038] The invention also relates to a buoyancy body for a floating functional unit, which is at least partially made from a rotor blade or part of a rotor blade of a wind turbine. In such a buoyancy body, it is provided that it consists of a section of a rotor blade or a longitudinal segment of a rotor blade from the leading edge to and including the spar, or from the trailing edge to and including the spar.

[0039] In such a buoyancy body, it may be provided that the rotor blade or part of a rotor blade is sealed at its end face by a liquid-tight closure body and / or has a liquid-tight subdivision of its length by at least one inserted bulkhead.

[0040] In another embodiment of a buoyancy body, it may also be provided that the rotor blade or part of a rotor blade has a hermetically sealed inner lining or one or more gas-filled, hermetically sealed air bags or a foam filling.

[0041] In addition to a floating functional unit and a buoyancy body, the invention also relates to a method for manufacturing a buoyancy body using a rotor blade of a wind turbine, in which, in at least one longitudinal section of the rotor blade, a region of the rotor blade is cut off along the leading edge from the leading edge to and including the support spar or from the trailing edge of the rotor blade to and including the support spar and is sealed thereon in a liquid-tight manner.

[0042] The invention is shown below with reference to exemplary embodiments in figures of a drawing and is subsequently described.

[0043] This shows

[0044] Figure 1: a schematic top view of a floating platform with buoyancy aids,

[0045] Figure 2: a top view of a floating jetty,

[0046] Figure 3: A top view of a platform with star-shaped arrangement

[0047] Buoyancy aids,

[0048] Figure 4: a cross-sectional view of a platform with buoyancy bodies of different sizes, Figure 5: a cross-sectional view with buoyancy bodies that are triangular in cross-section,

[0049] Figure 6: a side view of a platform with multiple staggered, continuous, long buoyancy bodies,

[0050] Figure 7: a cross-sectional view of a platform with vertically arranged buoyancy bodies,

[0051] Figure 8: a side view of a platform with short buoyancy bodies arranged in multiple staggered rows and lengthwise one behind the other,

[0052] Figure 9: a cross-sectional view of a rotor blade with indicated

[0053] sewing patterns,

[0054] Figure 10: a buoyancy aid in a side view,

[0055] Figure 11: the buoyancy body from Figure 10 in a cross-sectional view,

[0056] Figure 12: a floating platform with buoyancy aids in a perspective view, as well as

[0057] Figure 12: schematically a distribution of the buoyancy volumes of the functional unit in the horizontal direction.

[0058] Figure 1 shows a schematic top view of a platform 1 with buoyancy bodies 3a, 3b, 3c, 3d and a deck structure 2, where the individual buoyancy bodies each extend over the entire length of the platform. The center of gravity of the functional unit is labelled 30 in Figures 1 to 3.

[0059] The lift bodies are made from rotor blades or using longitudinal sections of rotor blades, with the individual rotor blades or rotor blade sections being aligned with their longitudinal axes 6 parallel to each other and, in the figure, alternately with the rotor blade tip pointing upwards and downwards. This arrangement allows a large number of rotor blade sections or rotor blades to be positioned close together.

[0060] The longitudinal axes 5 of the individual lift bodies, if they do not comprise a complete rotor blade, are defined such that they run parallel to the longitudinal axis of the rotor blade in the state in which the rotor blade sections are still part of the respective rotor blade. Figure 2 shows a top view of a floating platform 1 in the form of an elongated, narrow rib, with the individual lift bodies 3a, 3b, 3c, 3d arranged parallel to each other. In this top view, the individual lift bodies have an outer contour with an acute-angled triangular shape and are arranged below the deck of the deck structure 2. The tapered section of the individual lift bodies is alternately directed downwards and upwards, i.e., towards the two long boundary edges of the rib, when adjacent lift bodies are shown in the drawing.

[0061] Figure 3 shows a top view of a circular platform 2, beneath which lift bodies 3a, 3b, 3c, 3d are arranged in a star shape in the form of rotor blades. The orientation of the individual lift bodies is such that the large volume area of ​​each lift body is located radially outwards at the outer edge of the platform. This results in a lift force that increases rapidly with immersion depth when the platform is tilted, due to the large lift forces developed radially outwards. This orientation of the lift bodies thus achieves particularly high stabilization of the platform.

[0062] Figure 4 schematically shows a cross-section through a platform 1 with four buoyancy bodies 3a, 3b, 3c, 3d, arranged parallel to each other perpendicular to the plane of the drawing. Two large-volume buoyancy bodies 3a, 3d are arranged parallel to each other at the opposite boundary edges 8, 9 of the platform. The respective centers of volume 11a, 11b of the two large-volume buoyancy bodies 3a, 3d are located deeper in the water than the centers of volume 12a, 12b of the two smaller propulsion bodies 3b, 3c, which are arranged centrally between the large buoyancy bodies. This results in stronger buoyancy forces at the platform's outer edges than in the center, thus providing good stabilization against tilting. The buoyancy bodies are arranged symmetrically with respect to a longitudinal axis 7 of the platform perpendicular to the plane of the drawing, parallel to this longitudinal axis.

[0063] Figure 5 shows a cross-sectional view of another platform 1, in which the buoyancy bodies 3a, 3b, 3c, 3d are arranged vertically and at acute angles below the deck 2a of the platform structure 2. Due to the shape of the buoyancy bodies and their arrangement below the platform deck, the lift force, as a function of the immersion depth, is less pronounced at shallower depths than at greater depths, which result from higher loads. Consequently, the restoring force of the platform appears rather soft under dynamic loading until a certain tilt angle is reached. Suitable parts of rotor blades for such a platform include, for example, the rotor blade segments extending from the trailing edge of the blade to and including the spar.

[0064] Figure 6 shows a side view of a platform 1, which has long rotor blade segments 3a, 3b as lift bodies, each tapering to a point at one end. Adjacent rotor blade segments / lift bodies are arranged with their longitudinal axes 5 parallel to each other, with the tapered ends alternating in opposite directions. This arrangement of the lift bodies is similar to the arrangement shown in a top view in Figure 1. This arrangement of the rotor blades or rotor blade segments achieves the most uniform possible distribution of the lift volume over the platform's surface.

[0065] Figure 7 shows a cross-section of a platform with buoyancy bodies 3a, 3b arranged vertically and parallel to each other, with several rows of buoyancy bodies arranged one behind the other in the direction perpendicular to the plane of the drawing.

[0066] Such an arrangement is also shown in Figure 8, where the two rows of buoyancy bodies arranged parallel to each other are visible. Within each of the rows of buoyancy bodies, adjacent buoyancy bodies 3a, 3b are alternately oriented with their tapered ends pointing to the right or left in the drawing.

[0067] By using relatively short rotor blade segments as lift bodies in several consecutive rows, a particularly high utilization of the entire rotor blade length can be achieved when converting them into lift bodies. Figure 9 schematically shows a cross-sectional view of a rotor blade 4 of a wind turbine, with a perspective view of a portion of the rotor blade indicated in the figure. The rotor blade has a thin, sandwich-like shell 4c, which has a hard outer layer 4d, a hard inner layer 4e, and an intermediate layer 4f made of a lightweight material.

[0068] The spar 15, which is crucial for the stability of the rotor blade, is inserted between the lower and upper halves of the shell and bonded to the shell. In the respective area of ​​the shell to which the spar is attached, the shells are reinforced with so-called spar flanges 13, 14. These are particularly tensile-resistant and feature fiber reinforcement in the longitudinal direction of the rotor blade, i.e., parallel to its longitudinal axis 6. The shear stiffness of the rotor blade is essentially determined by the spar.

[0069] In Figure 9, the parts of a rotor blade that can advantageously be used as lift elements are grouped together in a first dashed box 21 and a second dashed box 22. The first dashed box 21 is intended to show that a D-shaped lift element can be formed by cutting the rotor blade longitudinally behind the spar, starting from the leading edge 4a. The leading edge of the rotor blade, from the leading edge 4a to and including the spar, is thus separated and can be used as a lift element along the entire length of the rotor blade or in sections. Since the rotor blade is often hollow, each longitudinal section of the rotor blade must be sealed with bulkheads at its ends before being used as a lift element.These bulkheads can be cut from parts of the rotor blade as surface elements of the shell, trimmed to size, and glued in place. This is shown by way of example in Figure 10 in a side view of a lift body 3a.

[0070] A second selection option for a buoyancy body cutout is shown in the second dashed box 22 of Figure 9. This selection encompasses the area of ​​a rotor blade from the trailing edge 4b ​​to and including the spar 15. The figures described above show examples of both types of buoyancy bodies in use for a floating platform. Particularly in the section between the spar and the trailing edge of the rotor blade, there are areas of the shell that have minimal curvature or are even flat, from which large plates can be cut out to form the deck of a platform. Such plate-like segments can be rigidly connected to each other or to the buoyancy bodies to achieve the desired shear stiffness of the platform in the horizontal direction.

[0071] Separately cut sections of the spar straps 13 and 14 can also be used in the construction of a floating platform. Since these straps have extremely high tensile strength, they can be used to brace the buoyancy bodies against each other.

[0072] Figure 11 shows a longitudinal view of a lift body 3a along its longitudinal axis, illustrating two different cross-sections corresponding to the pointed shape of the lift body. The lift body is oriented such that the spar of the rotor blade from which it is made is located on the upper surface and can be connected to a deck 2a of a floating platform's deck structure. In addition to the actual, plate-shaped deck, the deck structure may also include, for example, bracing elements that may extend partially into the spaces between the lift bodies.

[0073] Figure 10 shows a side view of the buoyancy body 3a as shown in Figure 11. The tapered shape is recognizable in the outer contour. Three bulkheads, 18, 19, are also shown on the buoyancy body. Two outer bulkheads, 17, 19, located on the star side, seal the volume of the hollow buoyancy body 3a, while a central bulkhead, 18, divides the buoyancy body into two longitudinal sections to ensure that, in the event of leaks, at least a sealed portion of the volume remains.

[0074] Figure 12 shows a perspective view of a floating platform 1 supported by buoyancy bodies 3a, 3b, 3c, 3d. The longitudinal axes 5 of the buoyancy bodies are parallel to each other and perpendicular to the plane of the drawing. Large buoyancy bodies 3a, 3d are arranged parallel to the outer edges 8, 9 of the platform on the left and right sides, respectively, with their longitudinal axes also parallel to the edges 8, 9. The cross-sectional areas of these large buoyancy bodies 3a, 3d are significantly larger than the cross-sectional areas of the smaller buoyancy bodies 3b, 3c located between them. The outer, large buoyancy bodies have a slightly conical shape tapering into the plane of the drawing and extend approximately to the center of the platform. Behind each of these buoyancy bodies 3a, 3d lies another buoyancy body of the same shape, which, however, is oriented in the opposite direction with respect to its conical shape.This results in a symmetrical distribution of the buoyancy volumes across the platform's surface. The two smaller buoyancy bodies 3b and 3c, arranged between the outer buoyancy bodies 3a and 3d and parallel to them, each extend over the entire length of the platform. These two middle buoyancy bodies each have a cross-section that varies only slightly along their length, so that there is no noticeably varying asymmetrical distribution of the buoyancy volume.

[0075] Above the buoyancy bodies 3a, 3b, 3c, 3d, a platform deck 2a is arranged, formed by planar, rectangular sections 16, 16a rigidly connected to one another, each cut from a relatively flat area of ​​a rotor blade 4. An example of such a flat area is shown in Figure 9. Since the rectangular sections within the deck are rigidly connected to one another, they provide sufficient shear stiffness of the platform in the horizontal direction. The platform can be further reinforced and stiffened by the use of spar caps 13, 14, which are also shown in Figure 9 and can be cut from a rotor blade.Since these spar chords are longitudinally fiber-reinforced and extremely tensile-resistant, they can significantly stiffen the platform if, for example, the spar chords are connected to the rectangular deck sections and / or to the undersides and / or tops of the buoyancy bodies 3a, 3b, 3c, 3d, for example by bonding. Figure 12 shows, by way of example, spar chords 13, 14 on the top of the deck and on the underside of the buoyancy bodies.

[0076] Figure 13 schematically shows a cross-sectional view of a functional unit 1 in the form of a symmetrically constructed floating platform. The center of gravity of the functional unit is located at point 30. From there, assuming the unit is floating in water, the distance to the outer edge 33 of the deck structure 2 is indicated by arrow 31 as 100% in the horizontal direction. Arrow 32, together with the distance line 36, indicates 70% of the horizontal distance from the center of gravity 30 to the outer edge 33. At least 50%, 55%, or 60% of the buoyancy volumes 3a, 3b, 3c, 3d are to lie outside this distance in the cross-section shown. In this representation, the smaller inner circles are of equal size, so that in this representation exactly 50% of the buoyancy volumes lie at a distance from the center of gravity 30 that is less than 70% of the distance to the outer edge, and 50% lie outside the distance range of 70%.

[0077] The larger circles 34 on the outside in the area outside the distance line 36 and the smaller circles 35 in the area inside the distance line 36 represent an example where, for instance, approximately 60% of the buoyancy volumes have a distance from the center of gravity 30 that is more than 70% of the distance of the outer edge 33 from the center of gravity.

[0078] The described method of reusing wind turbine rotor blades or parts thereof can result in significant material savings in the construction of floating platforms or floating watercraft. Provided the buoyancy bodies are of sufficient quality, this can reduce costs both in the construction of the floating functional units and in the disposal of the rotor blade material.

Claims

Fraunhofer Society...eV P149093PC00 Patent claims 1. Floating functional unit, in particular a floating platform (1) or watercraft, with several buoyancy bodies (3a, 3b, 3c, 3d) and a deck structure (2) with a deck (2a) arranged over the buoyancy bodies, wherein several of the buoyancy bodies each have a rotor blade (4) or a part, in particular a longitudinal section, of a rotor blade of a wind turbine, and wherein the buoyancy bodies are cut and arranged such that - from the center of gravity (30) of the functional unit, in at least one, in particular in each, horizontal direction, at least 50%, in particular at least 55% or 60% of the buoyancy volumes have a distance from the center of gravity in the horizontal direction that is at least 70% of the distance of the outer edge of the deck structure from the center of gravity in the same direction, or that, -outside a horizontal circle around the center of gravity (30) of the functional unit with a diameter equal to half the mean of the largest and smallest horizontal dimensions of the functional unit, more than 75%, in particular more than 80% or more than 85% of the buoyancy volumes are arranged.

2. Floating functional unit according to claim 1, characterized in that several or all buoyancy bodies (3a, 3b, 3c, 3d) are arranged parallel to each other with their longitudinal axes (5) which run parallel to the longitudinal axis (6) of the rotor blade within the rotor blade.

3. Floating functional unit according to claim 1 or 2, characterized in that the functional unit has a longitudinal axis (7) and buoyancy bodies (3a, 3b, 3c, 3d) of the same shape are arranged symmetrically, in particular mirror-symmetrically or point-symmetrically, to each other on both sides of the longitudinal axis.

4. Floating functional unit according to claim 1, 2 or 3, characterized in that buoyancy bodies (3a, 3b, 3c, 3d) are arranged directly along at least two opposing outer boundary edges (8, 9) of the functional unit and / or at four corners (10a, 10b, 10c, 10d) of the functional unit, the centers of volume (11a, 11b) of which are lower than the centers of volume (12a, 12b) of the buoyancy bodies arranged between them.

5. Floating functional unit according to claim 4, characterized in that the buoyancy bodies (3a, 3b, 3c, 3d) arranged along the outer boundary edges (8, 9) of the functional unit have a larger volume than the buoyancy bodies arranged between them.

6. Floating functional unit according to claim 1, characterized in that several buoyancy bodies (3a, 3b, 3c, 3d) are arranged in a star shape with respect to their longitudinal axes (5), which run parallel to the longitudinal axis (6) of the rotor blade within the rotor blade, wherein, in particular, in the case of a cross-sectional area that varies along the longitudinal axes of the buoyancy bodies, the area with the largest cross-sectional area points radially outwards.

7. Floating functional unit according to one of claims 1 to 6, characterized in that several buoyancy bodies (3a, 3b, 3c, 3d) are connected to each other by spar straps (13, 14) or parts of spar straps of rotor blades (4).

8. Floating functional unit according to one of claims 1 to 7, characterized in that several buoyancy bodies (3a, 3b, 3c, 3d) are connected to each other by plates (15, 16) made of the skin a rotor blade (4) in the area behind the support spar (15) are cut out.

9. Floating functional unit according to one of claims 1 to 8, characterized in that each of the buoyancy bodies (3a, 3b, 3c, 3d) is sealed liquid-tight with bulkheads (17, 18, 19) at one or both ends, wherein one or more buoyancy bodies in particular have one or more bulkheads for dividing their total volume into compartments separated from each other.

10. Floating functional unit according to one of claims 1 to 9, characterized in that an air bag (20) and / or a foam filling is provided within at least one of the buoyancy bodies (3a, 3b, 3c, 3d).

11. Buoyancy body (3a, 3b, 3c, 3d) for a floating functional unit, characterized in that it is at least partially made of a rotor blade (4) or a part of a rotor blade of a wind turbine and consists of a region of a rotor blade (4) or of a longitudinal section of a rotor blade from the leading edge (4a) to and including the support spar (15) or from the trailing edge (4b) to and including the support spar (15).

12. Buoyancy body according to claim 11, characterized in that the rotor blade (4) or part of a rotor blade is sealed liquid-tight at its end face by a closure body (17, 18, 19) and / or has a liquid-tight subdivision of its length by at least one inserted bulkhead.

13. Buoyancy body according to claim 11 or 12, characterized in that the rotor blade (4) or part of a rotor blade has a hermetically sealed inner lining or one or more gas-filled, hermetically sealed air bags (20) or a foam filling.

14. Method for manufacturing a buoyancy body (3a, 3b, 3c, 3d) using a rotor blade (4) of a wind turbine, thereby characterized in that in at least one longitudinal section of the rotor blade along the leading edge (4a) a region of the rotor blade from the leading edge to and including the spar (15) or from the trailing edge (4b) of the rotor blade to and including the spar (15) is cut off and sealed thereon in a liquid-tight manner.

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