Floating structure

Abstract

A novel floating structure is disclosed, comprising one or more floats formed from parts of a wind-turbine blade. Said one or more floats are supported or interconnected by a support structure that is formed at least partially from wind-turbine blade components.

Description

FLOATING STRUCTUREFIELD OF TECHNOLOGY

[0001] The present invention relates to the reuse of decommissioned wind turbine blades. In particular, the invention concerns the reuse of said blades as construction material for floating structures.BACKGROUND

[0002] The disposal of blades that have reached the end of their service life presents various challenges. Even now the blades currently being decommissioned are quite large, and due to technological advancements, the size of wind turbines has been continuously increasing. Because of the large space required, storing blades as such is not a practical long-term solution.

[0003] Numerous solutions have been considered for disposing of decommissioned blades, such as crushing the blades or breaking them down chemically. The problem with these approaches, however, is that due to the materials and mechanical properties of the blades, disposal requires significant amounts of energy and / or chemical processes, which are not environmentally friendly. Furthermore, converting the blade material into a reusable form (for example as crushed aggregate or powder) is often not economical, as the material typically loses its desirable properties during such conversion.SUMMARY

[0004] The purpose of the invention is to provide a means for addressing the challenges presented above. As a solution, a floating structure is presented in accordance with the first aspect of this description, the structure comprising one or more floats formed from parts of a wind-turbine blade, and / or a support structure that supports or connects the floats, the support structure being formed from parts of a wind-turbine blade. In some embodiments, said one or more floats comprise a float that includes a trunk section cut from a wind-turbine blade, the trunk section being a longitudinal portion of the blade, and at least one end of the trunk section being an open end formed by the cutting location, the perimeter of which is defined by the cutting edge of the cut. In some embodiments, at least one open end of the trunk section is closed with an end structure made from material cut from a planar internal support structurelocated inside the blade and connecting the opposing blade sidewalls. At least one groove extending along the edge of an open end of the trunk section may be formed, and at least one open end of the trunk section may be closed by a cover formed by a thermoplastic-polymer casting, the casting being shaped geometrically such that the surface it forms is mechanically locked to the open end. In some embodiments, said one or more floats comprise a float that includes two blade-root portions cut from a wind-turbine blade and attached to one another at their root ends.

[0005] Significant advantages are achieved with the float described above. On the one hand, the floating structure can be manufactured almost entirely from parts of a wind-turbine blade. On the other hand, the blade itself can be utilized in its entirety so that no scrap pieces remain. In this way, on the one hand the amount of other material required for manufacturing the float is minimized and, on the other hand, the need for further processing of waste generated from the used blade is minimized.

[0006] The second aspect of this description relates to the materials used. According to this second aspect, the floating structure may comprise one or more floats that are formed from parts of a wind-turbine blade and that are closed with a mineral-based structure. One or more sides of the float may, for example, be closed with a mineral-based composite or biostone. In some embodiments, one or more open ends of the trunk section may be closed with an end structure made of concrete that is reinforced with plastic or steel. At least one open end of the trunk section may also be closed with an end structure made of biostone formed on a metal mesh. In some embodiments, the float is partially or completely filled with foam glass or a foam-glass-based mineral composite. The floating structure may be modular. Said one or more floats may comprise a float that includes a trunk section cut from a wind-turbine blade, the trunk section being a longitudinal portion of the blade, and at least one end of the trunk section being an open end formed by the cutting location, whose perimeter is defined by the cutting edge of the cutting location.

[0007] Compared to a pontoon made entirely of concrete, a significant amount of material is saved, and the structure is considerably stronger than a pontoon whose core structure does not include a modular segment of a wind-turbine blade. In addition, the resulting structure is safe and durable.

[0008] A third aspect of this description relates to how wind-turbine blades are utilised in forming the floating structure. According to this third aspect, the floating structure may comprise one or more floats that are formed from parts of a wind-turbine blade and that have been longitudinallycut from the blade along the direction of the main support structure of the blade. One or more load-bearing sides may be cut longitudinally along the reinforcement. The structure may be modular. In one embodiment, said one or more floats comprise a float including a trunk section cut from a wind-turbine blade, the trunk section being a longitudinal portion of the blade, and at least one trunk section being attached to another to form T-shaped or L-shaped modules. The floating structure may be filled with foam glass, and the T- or L-shaped modules may form polygons that are easily connectable to one another. In one embodiment, the trunk sections are joined to one another using fully laminated parts of the blade.

[0009] On the one hand, longitudinal cutting facilitates the transport of a blade that would otherwise be excessively wide. On the other hand, when the blade is cut through at the spar cap, i.e. the main load-bearing beam, the laminate structure of the blade remains intact, or the extent to which it is opened can be minimised. Thus, the floating structure can be manufactured almost entirely from wind-turbine blade parts. Furthermore, the blade can be utilised in its entirety such that no scrap pieces remain. In this way, the amount of other material required for manufacturing the float is minimized, and, at the same time, the need for further processing of waste generated from the used blade is minimised.

[0010] A fourth aspect of this description concerns a manufacturing method for the float and the floating structure. The floats and floating structures described above in connection with the first, second and third aspects can be manufactured using the manufacturing method according to the fourth aspect. The manufacturing method may comprise steps in which a wind-turbine blade is received and a trunk section of the float is formed from a longitudinal portion cut from the blade. The open end or ends of the trunk section can be closed in many ways. For example, an open end may be closed with an end structure made from blade material. The float may also be closed with a mineral-based structure. In some embodiments of the manufacturing method, the longitudinal portion of the blade forming the trunk section is cut longitudinally along the direction of the main structure of the blade. In some embodiments of the manufacturing method, the method further comprises a step of connecting or supporting one or more floats with a support structure that is formed at least partly from parts of a windturbine blade.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Some embodiments of the invention are described in greater detail below with reference to the accompanying drawings, in which:Figures 1 a and 1 b show a simplified example of a typical wind turbine from different viewpoints,Figure 2 shows an individual blade of a wind turbine,Figure 3 shows a cross-sectional view of one example structure of a wind-turbine blade,Figure 4 shows a cross-sectional view of another wind-turbine blade structure,Figure 5 shows a cross-sectional view of one embodiment of a float,Figure 6 shows a side view of one embodiment of a float,Figure 7 shows a blade cross-sectional structure divided into segments,Figure 8 shows a cross-sectional view of a float according to one embodiment,Figure 9 shows a cross-sectional view of a float according to another embodiment,Figure 10 shows a cross-sectional view of a float according to a further embodiment,Figure 11 shows a cross-sectional view of a float according to yet another embodiment,Figures 12a and 12b show simplified cross-sectional views of a trunk section of a float according to one embodiment,Figure 13 shows a watercraft in which a float according to one embodiment is utilized, andFigure 14 shows a large-scale floating structure,Figure 15 shows a side view of one embodiment of a float,Figure 16 shows a view of a structure formed from floats,Figure 17 shows an embodiment that forms a T-shaped float,Figure 18 shows the float of Figure 5 viewed from below,Figure 19 shows a view of a hexagonal structure formed from floats,Figure 20 shows the structure of Figure 7 viewed from below,Figure 21 shows an embodiment that forms a T-shaped float as a double-float core,Figure 22 shows the float of Figure 9 viewed from below,Figure 23 shows a view of a square structure formed from the floats of Figure 9,Figure 24 shows the structure of Figure 11 viewed from below,Figure 25shows, in one embodiment, a modular massive comb structure formed on the basis of Figure 7, andFigure 26shows, in one embodiment, a modular massive comb structure formed on the basis of Figure 11 .DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0012] The following describes in greater detail various embodiments of floating structures according to the first aspect, comprising one or more floats formed from parts of a wind-turbine blade. In this context, the expression “wind-turbine blade” (or simply “blade”) refers to a rotor blade of a horizontal-axis wind turbine (HAWT). A horizontal-axis wind turbine rotor typically has three blades, which are attached at their root ends to the rotor hub and extend radially outward from the hub. The blades have an asymmetrical cross-section, and a given turbine has only one blade type (i.e. all blades have the same shape). However, the blade materials and exact geometry may vary between turbines depending on the manufacturer and year of manufacture.

[0013] Figures 1 a and 1 b show two simplified schematic views of a wind turbine 10 from different angles. The wind turbine 10 in Figures 1 a and 1 b has a rotor with a hub 12 and three rotor blades 14 attached at their root ends 14a to the hub 12. The length L of the rotor blade 14 is a dimension that extends radially outward from the rotor hub 12, relative to the axis of rotation R, between the blade root 14a and the blade tip 14b. The width W of the blade 14 is a dimension that extends in a rotational plane P of the blades that is perpendicular to the axis of rotation R. The thickness T of the blade 14 refers to the dimension that extends in the direction of the axis of rotation R, i.e. essentially transverse to the blade length L, the width W and the rotational plane P.

[0014] Figure 2 presents a schematic view of the details of a single blade. The blade may, for example, be similar to the blade shown in Figures 1 a and 1 b. The blade typically tapers in the longitudinal direction toward the tip 14b. The cross-section of the blade, for example at locations A1 , A2 and A3, may remain substantially similar in shape even though the blade tapers toward its tip 14b. In the root region 14a, however, the shape of the cross-section typically changes into a circular or oval form when approaching the root end.

[0015] Figures 3 and 4 show two simplified diagrams of a typical cross-sectional structure of a blade. The diagrams may represent, for example, cross-sections at locations A1 , A2 or A3 of Figure 2.

[0016] In Figure 3, the blade has, in the blade-width direction W, opposite leading edge 32 and trailing edge 36, and between the leading and trailing edges there extend, in the bladethickness direction T, two opposite sides that form the upper side 31 a and the lower side 31 b of the blade. With respect to the edges 32 and 36, the prefixes “leading” and “trailing” describe their position relative to the rotational direction of the rotor, i.e. the blade rotates such that its leading edge moves ahead. With respect to the sides 31 a and 31 b, the prefixes “upper” and “lower” do not refer to their relative positions in use, but rather to the conventional names given to the sides of a lift-generating airfoil. In wind-turbine use, this means that airflow directed, in the blade-thickness direction, from the lower side 31 b toward the upper side 31 a produces a force that tends to rotate the rotor in its rotational direction, i.e. such that the blade rotates with the leading edge 32 foremost.

[0017] On some portions of the blade cross-section there may be a layered (sandwich) structure. In this layered structure, a porous material is placed between two thin glass-fibre layers. In this way, the weight of the blade can be significantly reduced. In Figure 3, such a layered structure is present in the front portion of the blade, which is formed by the leading edge 32, the front part 32a of the upper side and the front part 32b of the lower side. In addition, the rear part 35a of the upper side and the rear part 35b of the lower side have a layered structure in Figure 3. Those portions of the blade for which particularly high strength is required may be of solid glass-fibre construction (made entirely of glass fibre throughout their thickness). In Figure 3, such portions are the trailing edge 36 and the central regions 34a and 34b of the upper and lower sides. In some embodiments, the leading edge 32 may also be made of solid glass fibre.

[0018] In Figure 3, the central upper portion 34a and the central lower portion 34b of the blade are joined by an internal, planar support structure 33, i.e., a shear web. The purpose of the support structure is to stiffen the blade, and it may be made of a different material than the central portions 34a and 34b. In some blades there is more than one such support structure. Figure 4 shows a cross-section of such a blade. In Figure 4, the central upper portion 44a and the central lower portion 44b of the blade are joined by two support structures 43.

[0019] Wind-turbine blades can, in accordance with the invention, be reused as construction material for the floats of floating structures.

[0020] One way of utilizing wind-turbine blades is to use sections of the blades largely as such, without substantial modifications to the shell structure of the blade. A floating structure may, for example, comprise a float that includes a trunk section cut from a wind-turbine blade. In this context, the term “cut” refers to dividing into parts by sawing, cutting (e.g. by water-jet cutting), or otherwise separating. By cutting the blade, its length - the dimension from the blade tip to the blade root - is shortened to a portion of its original length. The term “trunk section” refers to a longitudinal portion of the blade. The trunk section may thus be a substantially cylindrical object that forms the shell of the float. At least one end of the trunk section may be an open end formed by the cutting location (i.e. the location at which the blade has been separated into mutually separate pieces), the perimeter of which is defined by the cutting edge at the cutting location. The term “end” in this context refers to a bottom that bounds the shell of the trunk section. Preferably, the end has a planar shape whose perimeter is defined by the cutting edge.

[0021] The at least one open end mentioned above may, for example, be closed with an end structure made of blade material. Such material may, for example, be present in the inner walls of the blade. The term “inner wall” in this description refers to a planar support structure located inside the blade (i.e. in the cavity defined by the shell of the trunk section) which connects opposite sides of the blade. In Figures 3 and 4, such support structures are shown with reference numerals 33 and 43. In the context of this description, “closing” means rendering watertight. The joint between the trunk structure and the end structure may therefore be sealed with a sealing compound and / or material may be applied over the joint (for example, by laminating glass-fibre mat over the joint). The term “end structure” in connection with this embodiment refers to a substantially planar object formed from one or more pieces. Preferably, the end structure is a single integral piece, thereby minimizing the need for joints.

[0022] In some embodiments, the end structure that closes the open end may be a uniform planar end piece cut from said support structure of the same or another blade, which substantially corresponds to the shape and dimensions of the perimeter of the open end. The end piece may, for example, be a portion cut from the shear web using a template. In this way, the required end piece or pieces can be obtained from the same blade as the trunk section. The opening left in the shear web does not significantly affect the strength of the float trunk structure. The end piece may be dimensioned such that there is no substantial gap between the cutting edge and the end piece (preferably the end piece extends at least slightly beyond the inner surface of the cutting edge). In order to obtain a sufficiently large end piece to cover the open end opening, it may be cut from a thicker region of the blade. Since the blade narrowstowards its tip (and widens towards its root), such a thicker region can be found in the same blade.

[0023] In some embodiments, the closure of the open end may be carried out by a plastics casting. A cover may be formed at the open end, for example from a thermoplastic polymer such as polyethylene. Figures 12a and 12b show simplified cross-sectional views of a trunk section 121 whose open end is closed by a cover 125. Figure 12a shows a cross-section of the shell of the trunk section 121 cutting through the central upper portion 124a and the central lower portion 124b of the trunk section 121 . The cross-sectional view of Figure 12a may, for example, represent a cross-section taken along the line D1 shown in Figure 4. Figure 12b shows a detail from Figure 12a. In Figure 12b, the cover 125 closes the open end of the trunk section 121 so that the edge 126 of the shell of the trunk section 121 remains covered by the cover 125. The cover 125 may, for example, be 30-100 mm thick, or even thicker, and may extend in the longitudinal direction of the trunk section 121 along the inner surface 127 of the shell. The cover may also extend beyond the edge 126 over the edge of the trunk section 121 onto the outer surface 128 of the shell of the trunk section 121 .

[0024] As mentioned previously, part of the blade shell may be made of a sandwich-structured material. The cutting edge of the open end of the trunk section may, at least in the sandwich- structured regions, be covered with an epoxy filler, for example, so that the material in the middle of the sandwich structure, such as balsa wood, is protected against moisture.

[0025] In some embodiments, the plastic casting is shaped so that the surface it forms is mechanically locked to the open end. As illustrated, for example, in Figures 12a and 12b, the shell of the trunk section 121 may, at the edge 126 of the shell, be provided with at least one groove 129. The groove 129 may extend at least part of the way around the shell in the vicinity of the edge. The groove may be formed at least (or in some embodiments only) in the fully glass-fibre-laminated portions of the shell, such as in the central upper portion 124a and the central lower portion 124b of the trunk section 121 . The groove or grooves 129 may be formed, for example, on the inner surface 127 of the shell, as shown in Figures 12a and 12b, and / or on the outer surface 128. Instead of or in addition to the groove or grooves, holes may be formed in the shell that extend partway through the shell thickness or extend through the shell. By means of the grooves 129 (and / or holes), the cover 125 can be locked in place so that it cannot slide off from the open end of the trunk section 121 .

[0026] The coefficient of thermal expansion of the cover 125 formed from a thermoplastic polymer may differ from the coefficient of thermal expansion of the shell of the trunk section 121. However, the trunk section 121 is sufficiently rigid that it is able to maintain its shapedespite temperature variations and the forces arising from differences in the coefficients of thermal expansion between the cover 125 and the trunk section 121 . The structure of a windturbine blade is designed to flex, and therefore the trunk section 121 formed from the blade also yields with respect to thermal expansion and does not cause the cover 125 to crack. In addition, if necessary, the internal walls of the trunk section 121 may be removed so that the structure can flex even better in relation to thermal expansion. The cover 125 also mechanically supports the structure, particularly if the internal walls of the trunk section 121 have been removed. In cold conditions, the effect of thermal expansion may appear such that the outer edge of the cover 125 contracts and tightens firmly against the outer surface of the edge of the trunk section 121 . In warm conditions, on the other hand, the cover expands and presses against the inner surface of the edge of the trunk section. During manufacture, as the cover 125 cools it shrinks, whereby it grips tightly onto the trunk section and closes the trunk section into a mechanically sealed object.

[0027] A cover of the kind shown in Figures 12a and 12b may be formed in many ways. In one embodiment, the trunk section 121 may, for example, be immersed from its open end into a shallow, open mold that contains molten plastic, or into which molten plastic is poured, such that the edges of the open end of the trunk section are covered by the plastic and a cover 125 that spans the entire open end is formed. In another embodiment, the open end of the trunk section 121 is first covered with a film or a tarpaulin. The trunk section is then placed with the open end facing downward, and molten plastic is poured into the interior of the trunk section, where it settles against the film or tarpaulin and, upon solidifying, forms a cover for the open end. The cover is locked in place as it solidifies, for example by means of the grooves illustrated in Figures 12a and 12b. Such a cover does not necessarily extend past the edge of the open end onto the outer surface of the shell of the trunk section.

[0028] If the plastic cover is made thick, for example with a thickness greater than 100 mm, it may be particularly advantageous to manufacture it using recycled plastics, such as polystyrene (PS), polypropylene (PP), polyethylene (PE), or a mixture of two or more of these. In this way, two waste streams are combined into a product whose manufacture is scalable to an industrial level.

[0029] Although a plastic cover formed at the open end may to some extent adhere to the trunk section during manufacture, it is not in all embodiments the only or even the primary sealing means for closing the trunk section in a watertight manner. The joint between the cover and the trunk section can be sealed by other means as well, such as silicone-based seawaterresistant sealants, methyl methacrylate adhesives, epoxy adhesives used together with anHDPE primer, or polyurethane adhesives. These materials can also be used for sealing the joint between an end piece and the trunk section in the embodiments of Figures 3 and 4.

[0030] In addition to allowing the trunk section to be closed in a watertight manner, the plastic cover also improves the mechanical properties of the trunk section, particularly in those parts of the trunk section that are subject to wear due to use.

[0031] Above, two examples have been described in greater detail of how the open ends of the trunk section can be closed to make them watertight and to achieve sufficient mechanical locking between the element closing the open end and the trunk section. However, it is also possible to close the open ends in other ways. In some embodiments, the two covers closing the ends of the trunk section may be connected by bar-like structures that are wedge-shaped at their ends. These bar-like structures are preferably made from a material whose coefficient of thermal expansion corresponds to that of the trunk section. In this way, no substantial forces in the longitudinal direction of the trunk section arise in the covers as a result of temperature changes. In some embodiments, the internal walls of the trunk section may be shortened in the longitudinal direction of the trunk section so that an end piece formed from the blade or a molded plastic cover can be positioned inside the open end of the trunk section at the edge of the end, and so that the shortened internal wall supports that end piece or plastic molded cover.

[0032] Floats of the type described above may be manufactured in many shapes and configured to be oriented in different ways during use. Figures 10 and 11 show simplified schematic views of two embodiments and orientations of a float.

[0033] Figure 10 shows a short cylindrical float 100, which is configured to be used in a position in which one of its ends 102a faces downward during use and the other end 102b faces upward. At least one end 102a is therefore at least partially underwater during use, forming the bottom of the float. The structural part of the float is a portion of the blade taken along the blade’s longitudinal direction L. This longitudinal direction is oriented as the height H of the float 100 during use. As described earlier, a wind-turbine blade typically has strong, solid-fiberglass regions 104. Consequently, the attachment points 106 for anchoring the float 100 can be placed very close to the bottom of the float, thereby enabling a stable anchoring attachment.

[0034] Figure 11 shows an elongated cylindrical float 1 10, which is configured to be oriented with its longitudinal direction L substantially horizontal in the water. The opposite ends 112 of the float 1 10 in the longitudinal direction are thus essentially at the same level during use.

[0035] As mentioned previously, wind-turbine blades have an asymmetrical cross-section. This can also be seen, for example, in the cross-sectional views of Figures 3 and 4. If more symmetrical shapes are desired in the floating structure, an embodiment such as that shown in Figure 5 can be used. Figure 5 shows a cross-section of a floating structure in which two trunk sections 51 that correspond to one another are arranged with their undersides facing each other. These two trunk sections 51 may, for example, be made from the same regions of two identical blades. The ends of the trunk sections 51 can be closed with an end structure, for example in the same manner as in the embodiments described above, thereby forming two floats.

[0036] As shown in Figure 5, the floats are placed opposite each other and rotated 180 degrees relative to one another about their longitudinal axes. In some embodiments, the floats may be integrated into a single structure by fastening the trunk sections to each other through their shells using fastening elements (such as bolts) and / or by coating them with fiberglass and resin. In some embodiments, the fastening elements that pass through the shells can be placed in regions that consist entirely of fiberglass, such as positions B1 and B2 in Figure 5. The float according to Figure 5 may be configured, like the float in Figure 10, to be oriented with its longitudinal axis vertical, or, like the float in Figure 11 , to be oriented with its longitudinal axis horizontal.

[0037] Sections cut from the blade can also be joined to one another in other ways. In some embodiments, the floating structure may comprise a float that includes two blade root portions cut from a wind-turbine blade and attached to each other at their root ends. Since the crosssection of the blade root is circular or oval (and thus symmetrical), the roots can be arranged face to face such that the shell of the floating structure is, in the longitudinal direction, substantially smooth (without significant discontinuities). Figure 6 shows a simplified schematic view of such a floating structure. In this floating structure 60, sections 61 have been cut from the root portions of two identical blades and are then attached to each other at their root ends 61 b. Because the root ends are symmetrical, the joint 63 between the ends 61 b is even. In the embodiment of Figure 6, the open ends 61 a of the cut sections can be closed, for example, in the ways described above.

[0038] A floating structure comprising one or more floats according to the embodiments described above may be in the form of a floating structure intended to be anchored in a fixed location, such as a dock or dock module, a mooring buoy, a breakwater, a wave-energy generator float, or a navigation mark. Alternatively, the floating structure may take the form of a watercraft, such as a boat, raft, or unmanned marine vehicle (UMV). For example, the floating structure 60 of Figure 6 may form part of a watercraft. The floating structure 60 may,for instance, serve as the central hull of a trimaran vessel. In that case, instead of or in addition to a planar end structure, a wedge-shaped structure forming the bow of the watercraft may be provided at the end of the floating structure 60. Figure 13 illustrates an example of a watercraft hull structure 130 in the form of a trimaran, in which a structure corresponding to the floating structure 60 of Figure 6 is used as a central hull 132. In addition to the central hull 132, the hull structure 130 comprises, in the form of floating structures, side hulls 134 on both sides of the central hull 132. The side hulls 134 may, for example, be sections cut from wind-turbine blades. The central hull 132 and the side hulls 134 are connected to each other by crossbeams 136. The cross-beams 136 may likewise be sections cut from wind-turbine blades. In this way, pieces of wind-turbine blades can be used largely as such also in other applications than as floats.

[0039] Structural components formed from blade segments can be scaled to very large structures. It is, for example, possible to form floating structures that consist of segments from tens or even hundreds of blades. Figure 14 shows an example of a structure in which segments cut from dozens of blades have been used. The structure of Figure 14 forms a floating structure 140, in which dozens of blade root segments 142 are arranged upright in a ring shape. The root segments 142 are connected to each other by connecting pieces 144 formed from blade parts. The ring structures 140 can be dimensioned to support loads of tens or even hundreds of tonnes. The ring structure 140 forms a module, and several such modules can be connected to one another to produce massive floating structures, which may serve, for example, as foundations for floating villages or cities.

[0040] The preceding examples have described solutions in which blade segments are used largely as they are, without significant modifications to the blade shell structure. In addition to using larger segments cut from wind-turbine blades as float bodies, the blades can also be utilized when cut into smaller pieces. The following paragraphs present several examples of such modes of use. Although these smaller parts no longer, in isolation, constitute functional portions of a blade, the terminology used in this description for blade parts is nevertheless applied to them.

[0041] Figure 7 shows an example of how a blade according to Figure 4 can be divided into smaller pieces in the cross-sectional direction of the blade. In Figure 7, the blade has been divided into pieces along the boundaries of regions formed from different materials. The fullfiberglass portion at the trailing edge of the blade has been separated as its own piece 73. Likewise, the central regions of the upper and lower surfaces of the blade have been separated into their own pieces 74a and 74b. The rear regions of the upper and lower surfaces have also been separated into their own pieces 75a and 75b. The support structures connecting theupper and lower surfaces have likewise been separated into their own pieces 76. The front portion of the blade, which includes the leading edge and the front portions of the upper and lower surfaces, forms its own U-profile-shaped piece 72. In some embodiments, the blade can be divided into still smaller parts. For example, the pieces 72, 73, 74a, 74b, 75a, 75b, and 76 of Figure 7 may each be further divided into smaller beam-like, plank-like, or plate-like pieces. In Figure 7, for instance, the plate-like piece 75a formed from the rear upper surface can be divided into two pieces along the dividing line C1. This yields two wide, relatively flat planklike elements.

[0042] Smaller pieces cut from wind-turbine blades can be used, for example, as reinforcing support structures for floats. The floats described earlier can, for instance, be reinforced by attaching along the inside of their trunk sections, in the longitudinal direction, beam-like or plank-like reinforcing elements cut from the blade. If the trunk section of a float is formed from a blade whose leading edge does not include a full-fiberglass portion, the leading edge can be reinforced with such a reinforcing element.

[0043] Smaller pieces cut from the blades can additionally, or alternatively, be used in support structures that connect the floats of the floating structure. For example, beams and planks cut from the blades can be assembled into planar lattice structures to which floats can be attached and which serve as the frame of a jetty or jetty module. Planks cut from the blades can also be used in such jetties or jetty modules as cladding structures, for example as side cladding plates of the jetty and as deck plates or deck planks of the jetty.

[0044] In some embodiments, the blade cross-section is not divided completely into small pieces, but certain portions of the cross-section are left as elements that can be joined into larger units. Figures 8 and 9 illustrate two examples of this.

[0045] Figure 8 shows a cross-sectional view of one embodiment of a float formed by combining a front portion 82 cut from the blade and a rear portion 85 formed from the blade’s trailing edge and the rear upper and rear lower shell portions. The blade from which the front portion 82 and the rear portion 85 are taken may, for example, correspond to the examples of Figures 3 or 4. The float is reinforced internally at the joint between the front portion 82 and the rear portion 85 with beams 87 cut from blade material.

[0046] Figure 9 shows a cross-sectional view of another embodiment of a float. The float is formed from a portion 92 of the blade cross-section that includes the blade’s leading edge and the front and central parts of the upper and lower shells. In other words, the rear upper and rear lower shell portions and the trailing edge have been removed. The blade from which theportion 92 is taken may, for example, correspond to the example of Figure 4. The portion 92 includes internal support structures that connect the central upper and lower shell regions. The float of Figure 9 may be configured, for example, for use as a float of a jetty structure such that the float is oriented so that the leading edge 92a points downward during use and is submerged below the surface. In the embodiment of Figure 9, the leading edge 92a of the float’s front portion is reinforced with a reinforcing beam 96, which may be cut from the blade. At the opposite side of the float’s front portion (the upper side during use), a plate-like piece 95 cut from the blade is provided, which can serve as a deck structure.

[0047] According to the second aspect of this description, the floating structure or structures may be closed and / or filled with a mineral-based cover or filling. The at least one open end mentioned above may, for example, be closed with an end structure made predominantly of a mineral-based material, such as concrete or biostone, and reinforced with a steel structure or polymer fiber. In the context of this description, “closing” is understood to mean rendering watertight or forming a nearly watertight cavity or a closed pontoon structure.

[0048] The resulting cavity may be filled with foam glass or a composite thereof; in the case of a mineral composite, the additive either densifies and / or binds the foam glass together. Foam glass also stratifies toward the surface during casting, thereby lowering the center of gravity of the float. This method provides significant advantages, such as improved compressive strength of the float, a low center of mass, and support for the pontoon decks. It is also possible to cast only a foam-glass composite into the float, in which case it simultaneously forms the covers of the float.

[0049] Foam-glass composite can be formed by mixing foam glass, for example, with low- viscosity concrete, so that the concrete surrounds and binds the foam-glass particles (e.g. 60 mm) to each other, which improves durability and prevents the foam glass from becoming water-logged. This achieves significant advantages, in particular with respect to compressive strength and resistance to freezing.

[0050] Alternatively, the foam-glass composite can be formed by mixing foam glass with a thermoplastic polymer, such as recycled plastic. This yields significant advantages especially in applications where compressive strength is not so critical, but low weight and recyclability are more important.

[0051] Biostone can be formed by placing, for example, a metal mesh (e.g. a steel mesh) in the component and establishing a galvanic pair while the component is immersed in seawater, whereupon biostone begins to form on the metal surface and can close the structurecompletely. Biostone is thus formed from calcium and carbonate ions present in seawater, resulting in calcium carbonate.

[0052] In some embodiments, the end structure closing the open end may be provided at more than one end of the component, for example, the float 150 in Figure 15 may be closed both at the top and at the bottom.

[0053] In some embodiments, the open end can be closed by a concrete casting. A cover may be formed on the open end, for example, from fiber-reinforced concrete. Before casting, reinforcement bars may be installed, which can pass through the pontoon wall at locations that are made of thick fiberglass, for example.

[0054] As mentioned above, part of the blade shell may be made from a layered (sandwich) structure. The layered structure may first be closed with a thermoplastic polymer, for example polyethylene terephthalate, before casting.

[0055] In some embodiments, the concrete casting is shaped geometrically such that the surface it forms is mechanically locked to the open end.

[0056] As noted earlier, wind-turbine blades have an asymmetrical cross-section. This is also visible, for example, in the cross-sectional views of Figures 3 and 4 relating to embodiments of the first aspect. If more symmetrical shapes are desired for the floating structure, it is possible to use, for example, the embodiment of Figure 5. Figure 5 shows a cross-sectional view of a floating structure comprising two corresponding trunk sections 51 arranged opposite one another. These two trunk sections 51 may, for example, be made from the same regions of two identical blades. The ends of the trunk sections 51 may be closed with end structures in essentially the same manner as in the embodiments described for converting the blade sections into floats.

[0057] Based on the trunk section 51 , a float 150 may be produced, to which a cover 151 can be formed by casting. In this case, the cover 151 may serve as a walking surface, while the opposite side forms the bottom of the float.

[0058] The coefficient of thermal expansion of the mineral-composite cover 151 may differ from the coefficient of thermal expansion of the shell of the trunk section 152. The trunk section 152 is, however, sufficiently flexible that it can maintain its shape despite temperature variations and the forces arising from differences in the thermal expansion coefficients between the cover 151 and the trunk section 152. The structure of a wind-turbine blade is designed to flex, and consequently a trunk section 152 formed from the blade will also yieldwith respect to thermal expansion and will not cause the cover 151 to crack. In addition, if necessary, the internal walls 33 or 43 of the trunk section shown in Figures 3 and 4 may be removed so that the structure flexes even better with respect to thermal expansion.

[0059] A cover 151 of the type shown in Figure 15 may be formed in many ways. In one embodiment, the trunk section 150 may be inserted from its open end into a shallow, open mold that contains liquid concrete, or into which concrete is poured, such that the edges of the open end of the trunk section become embedded in the concrete and a cover 151 is formed across the entire open end. In another embodiment, the open end of the float 150 is first covered with a film or tarp. The trunk section is then placed with its open end facing downward and a flowable mineral composite is poured into the interior of the trunk section, where it settles against the film or tarp and, upon hardening, forms a cover for the open end. Such a cover may also extend beyond the edge of the open end onto the outer surface of the shell of the trunk section, or between two trunk sections.

[0060] In some embodiments, the concrete can also be “printed” using a 3D concrete casting machine, in which case reinforcement may not necessarily be required. This is advantageous for manufacturing large floats (with a float length, for example, exceeding 4 m), since the trunk section does not need to be turned upright for casting.

[0061] Although a mineral-based cover formed at the open end may, during manufacture, adhere to the trunk section to some extent, it is not in all embodiments the only or even the principal sealing means for closing the trunk section, which is integrated into a new circular- economy-based product using a minimal amount of concrete, resulting in a product that will last for decades.

[0062] In addition to providing a watertight closure for the trunk section, the cover also improves the mechanical properties of the trunk section, particularly in those portions of the trunk section (35a, 35b, 32a, and 32b in Figure 3) that are subject to wear or mechanical loading during use. The casting of the cover may also extend into the thinner walls (35a, 35b, 32a, and 32b) in the longitudinal direction L, thereby increasing their impact resistance.

[0063] Examples have been presented above in greater detail of how the open ends of the trunk section can be closed to make them watertight and to achieve sufficient mechanical locking between the element closing the open end and the trunk section. The covers may also form chambers into which water can gradually enter to provide ballast for the pontoon, thereby improving the behavior of the pontoon in waves or its stability in general.

[0064] Figure 150 shows an elliptical float 150 configured for use such that the cover 151 faces upward during operation and the opposite end faces downward. Thus, at least one end is at least partially under water during use, forming the bottom of the float. The other end may serve as a surface on which one can walk. The structural part of the float is a portion of the blade taken along the blade’s longitudinal direction L. As described earlier, a wind-turbine blade typically includes strong regions made from solid composite material (see, for example, Figure 3, reference numerals 34a, 34b or 44a and 44b).

[0065] The floats 15 can be connected to one another as shown in Figure 16, thereby forming a larger floating structure 162, for example 10 metres long and 5 metres wide, if the floats are formed from the blade regions A2-A3 shown in Figure 2. The same technique can be used over almost the entire length of the blade, although in the vicinity of the root 14a shown in Figure 2, circular pontoons are formed, and at the tip 14b the pontoons are rather small.

[0066] The structure 162 forms V-shaped recesses 164, which is advantageous in many ways. For example, this shape increases safety in dock use: if a person falls between a vessel and the dock, a ladder can be provided at a recess 164, and remains usable even when the vessel is leaning against the dock. In addition, fenders 165 can be mounted on the resulting U-shaped edges. Moreover, post-like structures 163a and 163b can be installed in these recesses 164. One of the post-like structures 163a can serve as an attachment point and chain well, and the other post-like structure 163b can serve as a lighting fixture and power outlet, which increases safety, for example by preventing cables from creating a tripping hazard on the dock.

[0067] A floating structure comprising one or more floats according to the embodiments of the second aspect described above may be in the form of a floating structure intended to be permanently anchored in place, such as a dock or dock module, a mooring buoy, a breakwater, a wave-energy generator float or a navigation mark. The structure may also be a slowly moving structure, for example a floating structure moving offshore, in which a large mass and modularity are advantageous.

[0068] According to the third aspect of this description, the floating structure may be formed by cutting the blade longitudinally along its length, as along the cutting plane D1 in Figure 4. This achieves significant advantages, since in that case the strongest part of the blade lies at the waterline of the structure, as well as at the edge of the float in those regions that are most likely to be subjected to impacts. When the layered structure is opened only minimally, any balsa wood present is less likely to become water-logged, because blades are in the first place manufactured using advanced techniques.

[0069] The at least one open end mentioned may be attached to another blade half side-by- side or at an angle of 90 degrees. The latter is the more advantageous alternative, since due to the curvature of the blade it is easiest to fasten them to one another at their ends, and the bolts in the root can also be utilised. This provides considerable advantages for the stability properties of the structure against waves, while on the other hand the structure can flex when necessary. In addition, the root portions are very strong in terms of thickness, and they are difficult to crush and cut, which is advantageous in float use.

[0070] The corner regions of the resulting structure can be reinforced, for example, with pieces cut from a circular sector of the blade root. Flat pieces cut from the blade’s main reinforcement can also be used as modular elements at connection points of the structure, as shown for example in Figure 18. This provides significant advantages in terms of ease of assembly and durability of the structure.

[0071] Figure 17 shows a T-shaped float, which is configured for use in such a way that, during use, the ends of the float point at a 90degree angle with respect to one another. There are two advantageous alternatives for forming this T-shape, as shown in Figures 17 and 21. Depending on the requirements of the floating structure, either the configuration in Figure 17 or that in Figure 21 may be more advantageous. This provides significant advantages in forming a strong structure and with regard both to wave reflection and to stability.

[0072] T-shaped modules can be joined together using blade pieces, either using pieces cut from the root or from the blade’s internal support structure. T-shaped modules can be joined into a hexagonal shape as in Figure 19, using six identical floats of Figure 17. Alternatively, L- shaped pieces can be formed from the structure of Figure 21 and used to form square modules, which have slightly better load-bearing capacity per unit area, as in Figure 23. A significant advantage of these modular floats is their strong structure and mutual compatibility. This yields considerable benefits for utilisation of the blade, since the above-mentioned techniques are compatible with the blade’s longitudinal twist.

[0073] Modular units such as those in Figures 19 or 23 can be connected to one another as shown in Figures 25 and 26, thereby forming a larger floating structure, for example 40 metres long and 40 metres wide (Figure 26). The same technique can be used over almost the entire length of the blade, although near the root stronger pontoons are formed, and near the tip the pontoons are rather small.

[0074] A floating structure comprising one or more floats according to the embodiments of the third aspect of this description described above may be in the form of a floating structureintended to be permanently anchored in place, such as a dock or dock module, a floating harbour, a breakwater, a wave-energy generator float or a floating village. The structure may also be a moving structure, for example a floating structure slowly moving offshore, in which a large mass and modularity are advantageous. In addition, it is possible to form moving vessels or rafts by placing blade halves crosswise on top of one another, thereby enabling the material itself to be transported economically, or to carry payload. This provides considerable advantages, in particular in forming cost-effective floats combined with a slightly flexible yet strong structure.

[0075] Although the first, second and third aspects of this description have been presented separately, their solutions may also be freely combined with one another. The teaching relating to the second aspect can, for example, be combined with the teaching relating to the first aspect, and the teaching relating to the third aspect can be combined with the teaching relating to the first and / or second aspect. For example, the trunk section or sections of a float can be formed in the manner described for the first or third aspect, and the trunk section or sections can be closed and / or filled in the manner described for the second aspect. A float can, for example, be formed as in Figure 6 and filled with foam glass. The trunk structure or structures of the float can also be formed in the manner of the third aspect represented in Figures 17 and 18 by splitting the blade longitudinally and filling the structure with a mineral structure in the manner of the second aspect. Multiple floats can be combined into modules. A floating structure can be formed from such floats or modules by connecting them to one another by a support structure as described in the first aspect.

Claims

PATENT CLAIMS1 . A floating structure, characterised in that the floating structure comprises:- one or more floats formed from parts of a wind-turbine blade; and- a support structure which supports or connects said one or more floats and which is formed at least partly from parts of a wind-turbine blade.

2. The floating structure according to claim 1 , wherein said one or more floats comprise a float which comprises:- a trunk section cut from a wind-turbine blade, the trunk section being a longitudinal portion of the blade, and at least one end of the trunk section being an open end formed by a cutting location, the perimeter of which is defined by a cutting edge of the cutting location.

3. The floating structure according to claim 2, wherein- at least one open end of the trunk section is closed by an end structure made from material cut from a planar internal support structure located inside the blade and connecting opposite side walls of the blade.

4. The floating structure according to claim 2, wherein- at least one groove extending along the edge is formed at the perimeter of at least one open end of the trunk section, and- at least one open end of the trunk section is closed by a cover-forming casting of thermoplastic polymer, the casting being shaped such that a surface formed thereby is mechanically locked to the open end.

5. The floating structure according to any one of the preceding claims, wherein said one or more floats comprise a float which comprises:- two blade root portions cut from a wind-turbine blade and attached to each other at their root ends.

6. The floating structure according to any one of the preceding claims, wherein the floating structure comprises:- one or more floats formed from parts of a wind-turbine blade and closed and / or filled with a mineral-based structure.

7. The floating structure according to claim 6, wherein- one or more of the floats is partially or completely filled with foam glass or a foamglass-based mineral composite.

8. The floating structure according to any one of the preceding claims, wherein the floating structure comprises:- one or more floats formed from parts of a wind-turbine blade which have been longitudinally cut through in the direction of the main support structure of the blade.

9. A float, characterised in that:- the float is formed from parts of a wind-turbine blade and is closed with a mineralbased structure and / or filled with a mineral-based material.

10. The float according to claim 9, comprising:- a trunk section cut from a wind-turbine blade, the trunk section being a longitudinal portion of the blade, and at least one end of the trunk section being an open end formed by a cutting location, the perimeter of which is defined by a cutting edge of the cutting location.11 . The float according to claim 9 or 10, wherein- the float is partially or completely filled with foam glass or a mineral composite based thereon.

12. The float according to any one of claims 9 to 11 , which is formed from parts of a wind-turbine blade and has been longitudinally cut through in the direction of the main support structure of the blade.

13. A manufacturing method, comprising the steps of:- receiving a wind-turbine blade;- forming a trunk section of a float from a longitudinal portion cut from the blade; and- closing the trunk section with a mineral-based structure and / or filling it with a mineral-based material.

14. The manufacturing method according to claim 13, comprising the step of:- cutting the longitudinal portion of the blade forming the trunk section longitudinally through in the direction of the main structure of the blade.

15. The manufacturing method according to claim 13 or 14, further comprising the step of:- connecting or supporting one or more floats by means of a support structure formed at least partly from parts of a wind-turbine blade.

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