A floating substructure for offshore wind turbines

Abstract

A floating substructure for supporting an offshore wind turbine includes a plurality of buoys arranged in a ring configuration and interconnected by articulating joints. A central column is positioned within the ring and is configured to receive and support a distal portion of a turbine tower. A plurality of first slings extends from a proximal region of the central column to corresponding articulating joints, and a plurality of second slings extends from a distal region of the central column to corresponding articulating joints. A plurality of anchors is positioned to anchor the substructure, and a plurality of third slings connects the anchors to the respective articulating joints. The arrangement of buoys, articulating joints, and sling systems provides a tension-based support structure suitable for deep-water offshore wind applications.

Description

[0001] - 1 -

[0002] A FLOATING SUBSTRUCTURE FOR OFFSHORE WIND TURBINES

[0003] Field of the Invention

[0004] The present invention relates to support structures for offshore installations and, more particularly, to support structures for offshore wind turbines.

[0005] Background of the Invention

[0006] Offshore floating structures are widely used in various marine industries, including offshore energy production, drilling operations, and floating wind turbine applications. Such structures must operate in environments characterized by waves, currents, wind loads, and considerable variations in water depth. As offshore operations move into deeper waters, floating platforms are increasingly required to maintain stability, support heavy superstructures, and withstand environmental forces while remaining cost-effective to manufacture, transport, and install.

[0007] For offshore wind applications, floating platforms may need to support substantial tower and turbine masses at large elevations above the waterline. This requirement may increase the structural weight of the platform itself, as additional buoyancy, stiffness, and strength may be needed to control motions and maintain adequate stability. Increased platform weight may in turn raise material costs, fabrication time, and transport requirements.

[0008] Heavier floating platforms may also impose significant installation complexity. For example, moving, deploying, ballasting, or mooring large-mass offshore structures may require specialized vessels, high-capacity cranes, deep-water port facilities, and extended offshore operations. These factors may increase project cost, schedule duration, and overall logistical difficulty. - 2 -

[0009] Accordingly, there is an ongoing need for floating offshore structures that may provide improved stability, reduced motion under environmental loading, and sufficient support for tall and heavy superstructures, while also reducing platform weight and simplifying assembly, transport, and installation operations in deepwater environments.

[0010] Summary of the Invention

[0011] The present invention provides a floating substructure for supporting an offshore wind turbine. The substructure may include a plurality of buoys arranged in a ring configuration. Each buoy may be formed of a material configured to resist compressive loading. Adjacent buoys may be interconnected by a plurality of articulating joints. A central column may be positioned within the ring configuration and may be structured to receive and support a distal portion of a turbine tower. A plurality of first slings may extend from a proximal region of the central column to corresponding articulating joints, and a plurality of second slings may extend from a distal region of the central column to corresponding articulating joints. A plurality of anchors may be positioned to anchor the substructure, and a plurality of third slings may connect respective anchors to corresponding articulating joints.

[0012] In some embodiments, a floating substructure for supporting an offshore wind turbine includes a plurality of buoys arranged in a ring configuration, each buoy being formed of a material configured to resist mainly compressive loading. In some embodiments, the floating substructure includes a plurality of articulating joints, each articulating joint interconnecting adjacent buoys. In some embodiments, the floating substructure includes a central column positioned within the ring configuration of buoys and configured to receive and support a distal portion of a turbine tower. In some embodiments, the floating substructure includes a plurality of first slings extending from a proximal region of the central column to corresponding articulating joints, and a plurality of second slings extending from a distal region of the central column to corresponding articulating joints. In some - 3 - embodiments, the floating substructure includes a plurality of anchors positioned to anchor the substructure and a plurality of third slings, each third sling connecting a corresponding anchor to a respective articulating joint.

[0013] In some embodiments, each one of the plurality of first slings, the plurality of second slings, and the plurality of third slings comprises one or more tension elements and one or more connection elements, each connection element being configured to attach the tension elements to a corresponding articulating joint and to the proximal region of the central column, the distal region of the central column, and the corresponding anchor, respectively.

[0014] In some embodiments, each buoy comprises two opposing cone-shaped elements joined together at a mid-region of the buoy, and each cone-shaped element is hollow.

[0015] In some embodiments, each articulating joint interconnecting adjacent buoys comprises a structural element having spherical bearing surfaces arranged to mate with corresponding spherical bearing surfaces provided at apex regions of cone- shaped elements of the respective buys, the spherical bearing surfaces being arranged so that a center of rotation is located at a center of the structural element.

[0016] In some embodiments, each first sling, each second sling, and each third sling connected to a respective articulating joint is arranged such that a tension line of action of each first sling, a tension line of action of each second sling, and a tension line of action of each third sling intersect at a point located at a center of the structural element of the respective articulating joint.

[0017] In some embodiments, the material configured to resist mainly compressive loading comprises concrete.

[0018] In some embodiments, the plurality of first slings is arranged in pairs and the plurality of second slings is arranged in pairs, each pair of the plurality of first slings - 4 - and each pair of the plurality of second slings being arranged so that the slings of each pair share tensile load and so that, in the event one sling of the pair fails, the other sling of the pair is configured to assume the tensile load carried by the failed sling.

[0019] In some embodiments, the plurality of first slings is pre-tensioned so that the plurality of first slings is configured to resist heeling of the turbine tower by exerting a restoring moment.

[0020] In some embodiments, the articulating joints are configured such that the structural stiffness of the ring configuration of buoys is determined primarily by the stiffness of the plurality of first slings and the plurality of second slings and the plurality of third slings.

[0021] In some embodiments, each buoy is connected at its ends to the respective articulating joints in a manner that permits rotational freedom at buoy ends, thereby reducing bending moments induced by buoyancy and hydrodynamic forces.

[0022] In some embodiments, each anchor is configured to attach and secure an end of a respective third sling to a seabed, the tension in the third sling being generated by the buoyant forces acting on the substructure.

[0023] In some embodiments, each buoy is configured with an external volume selected such that the combined buoyancy of the plurality of buoys provides a buoyancy force sufficient to support the weight of the turbine tower and the substructure.

[0024] In some embodiments, the cone-shaped elements of each buoy form a double-cone geometry having a maximum diameter at the mid-region, the maximum diameter configured to provide an increased moment of inertia of a cross-section of the buoy and reducing bending stress arising from transverse buoyancy forces and hydrodynamic loading. - 5 - ln some embodiments, a method of installing a floating substructure for supporting an offshore wind turbine includes lowering a plurality of support columns or part of the support column into a body of water to a position in which the plurality of support columns extend from a water surface toward a seabed, wherein each support column of the plurality of support columns comprises a temporary buoy, an articulating joint releasably attached to the temporary buoy, a first sling, a second sling, a third sling, and an anchor, wherein the first sling, the second sling, and the third sling are connected to the articulating joint, and wherein the anchor is connected to the articulating joint by the third sling, with the temporary buoy located above the articulation joint and the anchor disposed on the seabed. In some embodiments, the method includes positioning a plurality of buoys in a ring configuration, each buoy from the plurality of buoys being positioned between adjacent support columns, and interconnecting adjacent buoys using the articulating joints of corresponding support columns. In some embodiments, the method includes positioning a central column within the ring configuration. In some embodiments, the method includes connecting a plurality of second slings between a distal region of the central column and corresponding articulating joints and connecting a plurality of first slings between a proximal region of the central column and corresponding articulating joints.

[0025] In some embodiments, the method includes assembling each support column or part of the support column of the plurality of support columns prior to lowering the plurality of support columns into the body of water.

[0026] In some embodiments, the method includes installing a bridge member between two support columns to temporarily ensure the attachments between the buoys and the articulating joint during assembly.

[0027] In some embodiments, the method includes removing the temporary buoys at the end of the installation process. - 6 -

[0028] Advantageously, the present invention provides a floating substructure that supports an offshore wind turbine while reducing structural weight and installation complexity. By employing a plurality of buoys arranged in a ring configuration and interconnected by articulating joints, and by routing primary load paths through the plurality of first slings, the plurality of second slings, and the plurality of third slings, the system directs operational forces into tension rather than bending or shear, thereby enabling reductions in material usage. The option of use of anchors connected to the articulating joints by the third slings simplifies anchoring operations and avoids the need for complex seabed installations. In this manner, the substructure provides improved stability for supporting a turbine tower while allowing reduced fabrication effort, reduced mass, and reduced offshore installation demands relative to other floating offshore structures.

[0029] The described configuration also provides specific assembly and structural benefits. The arrangement of slings and articulating joints facilitates ease of assembly, as buoys and joints may be aligned and engaged without the need for precise rotational positioning. The articulating engagement reduces the likelihood of accidental damage or breakage due to misalignment during assembly. The alignment of the tension lines of action of the first slings, second slings, and third slings so that they intersect at the intended intersection point within each articulating joint ensures, neglecting friction forces, that the primary forces are transmitted through the central region of the structural element and that unwanted rotation of the joint is avoided. Furthermore, the structural stiffness of the resulting ring configuration is governed primarily by the stiffness of the slings rather than by the bending stiffness of the buoy cross-sections, thereby reducing bending moments induced by buoyancy and hydrodynamic forces.

[0030] Brief Description of the Drawings

[0031] In the drawings: - 7 -

[0032] FIG. 1 is a side view of an offshore wind turbine mounted on a floating substructure, according to some embodiments of the invention;

[0033] FIG. 2 is a perspective view of a floating substructure, according to some embodiments of the invention;

[0034] FIG. 3 is a cutaway side view of an upper portion of a floating substructure, according to some embodiments of the invention;

[0035] FIG. 4 is an enlarged view of adjacent buoys and an articulating joint, illustrating the spherical bearing surfaces and the attachment of a plurality of first slings, a plurality of second slings, and a plurality of third slings, according to some embodiments of the invention;

[0036] FIG. 4A is an enlarged view of the central column, illustrating the connection points provided for attachment of the first slings and the second slings, according to some embodiments of the invention;

[0037] FIG. 4B is an enlarged view of an articulating joint, illustrating the connection points provided for attachment of the first slings, the second slings, and the third slings, according to some embodiments of the invention;

[0038] FIG. 5 is a view of a plurality of support columns after lowering, according to some embodiments of the invention;

[0039] FIG. 5A is a view of a support column, according to some embodiments of the invention;

[0040] FIG. 6A is an enlarged perspective view of a buoy positioned between two support columns, according to some embodiments of the invention;

[0041] FIG. 6B is a perspective view of a plurality of buoys positioned between a plurality of support columns during assembly, according to some embodiments of the invention;

[0042] FIG. 6C is a perspective view showing a central column positioned within a ring configuration of a plurality of buoys, after lowering to a depth that enables connection of the second slings, according to some embodiments of the invention;

[0043] FIG. 6D shows a close-up view of the central column in a state that the plurality of the second slings are connected to the central column and the first slings are close to the state that enables connection, according to some embodiments of the invention; - 8 -

[0044] FIG. 6E illustrates a side view of an upper portion of the floating substructure after installation7according to some embodiments of the invention;

[0045] FIG. 7A illustrates an enlarged view of an upper portion of the support column, according to some embodiments of the invention;

[0046] FIG. 7B illustrates an enlarged view of a bottom portion of the support column, according to some embodiments of the invention; and

[0047] FIG. 8 illustrates a flowchart of a method for installing a floating substructure, according to some embodiments of the invention.

[0048] Detailed Description of the Invention

[0049] Referring now to FIGS. 1-4B: FIG. 1 is a side view of an offshore wind turbine 70 mounted on a floating substructure 100, according to some embodiments of the invention. FIG. 2 is a perspective view of a floating substructure 100, according to some embodiments of the invention. FIG. 3 is a cutaway side view of-the upper portion of a floating substructure 100, according to some embodiments of the invention. FIG. 4 is an enlarged view of adjacent buoys 110 and an articulating joint 120, illustrating the spherical bearing surfaces 122, 123 and the attachment of a plurality of first slings 140 and a plurality of second slings 150, according to some embodiments of the invention. FIG. 4A is an enlarged view of the central column 130, illustrating the connection points 141 and 151 provided for attachment of the first slings 140 and the second slings 150, according to some embodiments of the invention. FIG. 4B is an enlarged view of an articulating joint 120, illustrating the connection points 141a, 151a, and 161a provided for attachment of the first slings 140, the second slings 150, and the third slings 160, according to some embodiments of the invention.

[0050] The floating substructure 100 for supporting an offshore wind turbine may include a plurality of buoys 110 arranged in a ring configuration. Each buoy 110 may comprise two cone-shaped elements 113 joined together at a mid-region 115. Each cone- shaped element 113 may be hollowed for reducing its weight, and in order to create - 9 - sufficient external volume. The external volume, according to Archimedes' law, determines the buoyancy force required to carry the turbine and its substructure.

[0051] The axial compression forces 173a and 173b that are induced on each buoy 110 by the slings' radial force 173 and the external hydrostatic pressure are inducing mainly compressive stresses on the envelope of the buoy 110. This gives rise to the option to select a brittle material like concrete for cones 113, due to its good durability under compressive stresses / loading. In this case, the required reinforcement, for example, by steel reinforcement, would be minimal. For instance, applying a steel hoop at the mid-region 115 of the buoy 110 to restrict hoop tensile strains associated with the axial force 173a or 173b.

[0052] A plurality of articulating joints 120 may interconnect adjacent buoys 110 in the ring configuration. Each articulating joint 120 may include a structural element 121 having spherical bearing surfaces 122, which may be arranged to mate with corresponding spherical bearing surfaces 123 provided at apex regions of the cone- shaped elements 113 of the respective buoys 110. The spherical bearing surfaces 122, 123 may be arranged so that the center of rotation may be located at the center of the structural element 121. The articulation provided by the articulating joints 120 may permit rotational freedom at the ends of each buoy 110, thereby reducing bending moments in the buoy 110 that may be induced by buoyancy and hydrodynamic forces or by misalignment, namely deviations of the orientations of the buoys from the nominal state. The articulation provided by the articulating joints 120 may allow the structural stiffness of the ring configuration of buoys 110 to be determined primarily by the stiffness of the plurality of first slings 140 and the plurality of second slings 150.

[0053] In certain embodiments, the engagement between the buoy 110 and the structural element 121 may be maintained by compressive forces 173a and 173b induced - 10 - through the slings 140 and 150, thereby avoiding the need for bolts or other fastening hardware.

[0054] A central column 130 may be positioned within the ring configuration of buoys 110 and may be configured to receive and support a distal portion of a turbine tower 70. The central column 130 may include a proximal region 131 and a distal region 132. A plurality of first slings 140 may extend from the proximal region 131 of the central column 130 to corresponding articulating joints 120, and a plurality of second slings 150 may extend from the distal region 132 to corresponding articulating joints 120. The plurality of first slings 140 may be arranged in pairs, and the plurality of second slings 150 may be arranged in pairs, the slings of each pair being arranged so that they may share tensile load and so that, if one sling of a pair fails, the other sling may assume the entire tensile load.

[0055] The plurality of first slings 140 may connect to first central column connection points 141, which may be provided on the proximal region 131 of the central column 130, and to corresponding first articulating joint connection points 141a provided on the articulating joints 120. The plurality of second slings 150 may connect to second central column connection points 151, which may be provided on the distal region 132 of the central column 130, and to corresponding second articulating joint connection points 151a provided on the articulating joints 120.

[0056] Each of the first slings 140, second slings 150, and third slings 160 may comprise one or more high-strength tension elements configured to sustain continuous loading under marine conditions. In some embodiments, the tension elements may include steel structural strands, synthetic fiber ropes, or other flexible high-tensile-strength materials, provided individually or in parallel. The slings may further include one or more connection elements 171 at their edges, which may be embodied as sockets, sleeves, clevis fittings, or other mechanical terminations configured to secure the tension elements to the corresponding attachment structures, including the - 11 - articulating joints 120, the proximal region 131 or distal region 132 of the central column 130, and the respective anchors 180.

[0057] The first slings 140 may be pre-tensioned in order to enhance their resistance to heeling of the turbine tower 70 by generating restoring moments in response to small angular displacements of the central column 130. Each first sling 140, second sling 150, and third sling 160 may be oriented so that its tension line of action 173 intersects the center of the structural element 121 of the corresponding articulating joint 120.

[0058] In some embodiments, the proximal region 131 may include an axial opening configured to receive the distal portion of the turbine tower 70. The central column 130 may further include a wall structure extending between the proximal region 131 and the distal region 132, the wall structure defining an interior cavity that surrounds the distal portion of the turbine tower 70 when received within the axial opening and that transfers operational loads to the plurality of first slings 140 and the plurality of second slings 150.

[0059] The bottom edge of the central column 130 may be closed, creating an internal empty cavity and providing an additional buoyancy force. Additionally, during the installation process, this enables the controlled submersion of the central column through water ballasting.

[0060] In some embodiments, the central column 130 may be structured as a truss. In this embodiment, the central column 130 may comprise a framework of interconnected structural slender members arranged to define the proximal region 131, the distal region 132, and intermediate portions of the column. The structural members may form the primary load paths for axial, bending, and torsional loads generated by the - 12 - turbine tower 70 and may transfer these loads to the plurality of first slings 140 and the plurality of second slings 150 through the corresponding central column connection points located at the proximal region 131 and the distal region 132. The truss configuration may reduce mass while providing the stiffness required to transfer operational loads into the plurality of first slings 140 and the plurality of second slings 150.

[0061] A plurality of anchors 180 may be positioned to anchor the substructure 100, and a plurality of third slings 160 may extend between the anchors 180 and the respective articulating joints 120. In some embodiments, each third sling 160 may connect to third articulating joint connection points 161a provided on the articulating joints 120 and to corresponding anchor connection points provided on the respective anchors 180. The third articulating joint connection points 161a may be formed on the structural element 121 of each articulating joint 120, and the anchor connection points may be formed on the upper attachment structure of each anchor 180.

[0062] The task of the anchor 180 is to attach / secure the bottom edge of the third sling 160 to the seabed. The tension of the third slings is created by buoys 110. In some embodiments, the anchors 180 may be of a gravity type of sufficiently small mass that enables dropping to the seabed 60 without the need for complex seabed preparation and complicated equipment. Adjustment of the length or pre-tension of the third slings 160 during installation may be used to correct or reduce nonuniformities in tension that arise from variations in seabed elevation.

[0063] In some embodiments, each buoy 110 may be configured with an external volume defined by the outer geometry of the buoy, including the outer surfaces of the cone- shaped elements 113. The external volume may determine the amount of water displaced by the buoy and therefore the buoyancy force it generates. The external volume of each buoy may be selected such that the combined buoyancy of the - 13 - plurality of buoys 110 provides a buoyancy force sufficient to support the weight of the turbine tower 70 and the floating substructure 100.

[0064] In some embodiments, the opposing cone-shaped elements of each buoy may form a double-cone geometry having a maximum diameter at the mid-region 115. The maximum diameter may increase the moment of inertia of the buoy cross-section and thereby reduce bending stress arising from transverse buoyancy forces and hydrodynamic loading.

[0065] Referring now to FIGS. 5-8: FIG. 5 is a schematic view of a plurality of support columns 500 during lowering, according to some embodiments of the invention. FIG. 5A is a view of a support column 500, according to some embodiments of the invention. FIG. 6A is an enlarged perspective view of a buoy 110 positioned between two support columns 500, according to some embodiments of the invention. FIG. 6B is a perspective view of a plurality of buoys 110 positioned between a plurality of support columns 500 during assembly, according to some embodiments of the invention.

[0066] FIG. 6C is a perspective view showing a central column 130 positioned within a ring configuration of a plurality of buoys 110, according to some embodiments of the invention.

[0067] FIG. 6D shows a close-up view of the central column 130 with the plurality of first slings 140 and the plurality of second slings 150, according to some embodiments of the invention. - 14 -

[0068] FIG. 6E illustrates a side view of the floating substructure 100 with the buoys 110, the articulating joints 120, the central column 130, and the slings 140, 150, 160, according to some embodiments of the invention.

[0069] FIG. 7A illustrates an enlarged view of a articulating joint 120 connecting a temporary buoy 510, a buoy 110, and pluralities of slings 140, 150, 160, according to some embodiments of the invention.

[0070] FIG. 7B illustrates an enlarged view of a anchor 180, according to some embodiments of the invention. FIG. 8 illustrates a flow chart of a method 800 of installing a floating substructure, according to some embodiments of the invention.

[0071] FIG. 5 is a view of a plurality of support columns 500 after lowering, according to some embodiments of the invention.

[0072] FIG. 6A is an enlarged perspective view of a buoy 110 positioned between two support columns 500, according to some embodiments of the invention. FIG. 6B is a perspective view of a plurality of buoys 110 positioned between a plurality of support columns 500 during assembly, according to some embodiments of the invention.

[0073] FIG. 6C is a perspective view showing a central column 130 positioned within a ring configuration of a plurality of buoys 110 after lowering to a depth that enables connection of the second slings, according to some embodiments of the invention. FIG. 6D shows a close-up view of the central column in the state that the plurality of the second slings 140 are connected to the central column and the first slings 150 are close to the state that enables connection, according to some embodiments of the invention. FIG. 6E illustrates a side view of the upper portion of the floating substructure 100 after installation, according to some embodiments of the - 15 - invention. FIG. 7A illustrates an enlarged view of the upper portion of a support column 500, including articulating joint 120, connecting a temporary buoy 510, a buoy 110, and pluralities of slings 140, 150, 160, according to some embodiments of the invention. FIG. 7B illustrates an enlarged view of a anchor 180, according to some embodiments of the invention. FIG. 7B illustrates an enlarged view of the bottom portion of the support column 500, including a anchor 180 and connection to third sling, according to some embodiments of the invention. FIG. 8 illustrates a flow chart of method 800 of in the installing process of a floating substructure, according to some embodiments of the invention.

[0074] A method 800 of installing a floating substructure for supporting an offshore wind turbine (e.g., floating substructure 100) may begin at step 810 with lowering a plurality of support columns (e.g., support columns 500) into a body of water to a position in which the plurality of support columns may extend from a water surface 50 toward a seabed.

[0075] Each support column of the plurality of support columns may include a temporary buoy (e.g., temporary buoy 510), an articulating joint (e.g., articulating joint 120) releasably attached to the temporary buoy, a first sling (e.g., first sling 140), a second sling (e.g., second sling 150), a third sling (e.g., third sling 160), and a anchor (e.g., anchor 180). The first sling, the second sling, and the third sling may be connected to the articulating joint, and the anchor may be connected to the articulating joint by the third sling. During lowering, the temporary buoy may remain located at or near the water surface while the anchor may descend toward the seabed.

[0076] Each support column of the plurality of support columns may be assembled prior to lowering the plurality of support columns into the body of water. - 16 -

[0077] At step 820, a plurality of buoys (e.g., buoys 110) may be positioned in a ring configuration, each buoy from the plurality of buoys being positioned between adjacent support receptacles, and adjacent buoys may be interconnected using the articulating joints of corresponding support columns.

[0078] Each buoy of the plurality of buoys may be attached to corresponding articulating joints of adjacent support columns prior to positioning the plurality of buoys in the ring configuration.

[0079] A bridge member (e.g., bridge member 520 may be installed between two support columns 500 to temporarily ensure the attachments between the articulation joints 120 and the buoys 110 during assembly.

[0080] At step 830, a central column (e.g., central column 130) may be positioned within the ring configuration. The central column may be lowered or guided into the central region defined by the plurality of buoys. In some embodiments, the lowering of the central column may be performed by water ballasting.

[0081] At step 840, a plurality of second slings (e.g., second slings 150) may be connected between a distal region (e.g., distal region 132) of the support receptacles and corresponding articulating joints. Each of the plurality of second slings may be secured at one end to the distal region and at another end to the corresponding articulating joint.

[0082] At step 850, a plurality of first slings (e.g., first slings 140) may be connected between a proximal region (e.g., proximal region 131) of the support receptacle and corresponding articulating joints. Each of the plurality of first slings may be secured - 17 - at one end to the proximal region and at another end to the corresponding articulating joint.

[0083] The temporary buoys may be removed on completion of connecting the plurality of first slings and the plurality of second slings.

[0084] The foregoing description sets out examples to aid understanding and is not intended to limit the scope of the invention. Features described in connection with any embodiment may be used alone or in any technically feasible combination with features of other embodiments unless stated otherwise. Reference numerals are for convenience and do not limit the features they identify. Directional and positional terms (e.g., upper / lower, inner / outer) refer to the orientations shown in the drawings and may vary in use. Numerical values stated as "about" indicate reasonable approximation; stated ranges include their endpoints and all sub-ranges. Unless the context indicates otherwise, the singular may include the plural and the plural may include the singular, and "or" is intended to be inclusive. The terms "include," "includes," and "including" are intended to be non-limiting and mean "including without limitation." The scope of the invention is defined by the claims, and all modifications that fall within the meaning and range of equivalency of the claims are intended to be covered.

Claims

- 18 -Claims1. A floating substructure for supporting an offshore wind turbine, comprising: a) a plurality of buoys arranged in a ring configuration; b) a plurality of articulating joints, each articulating joint interconnecting adjacent buoys; c) a central column positioned within the ring configuration of buoys and configured to receive and support a distal portion of a turbine tower; d) a plurality of first slings extending from a proximal region of the central column to corresponding articulating joints; e) a plurality of second slings extending from a distal region of the central column to corresponding articulating joints; f) a plurality of anchors positioned to anchor the substructure; and g) a plurality of third slings, each third sling connecting a corresponding anchor to a respective articulating joint.

2. The substructure of claim 1, wherein each one of the plurality of first slings, the plurality of second slings, and the plurality of third slings comprises one or more tension elements and one or more connection elements, each connection element being configured to attach the tension elements to a corresponding articulating joint and to the proximal region of the central column, the distal region of the central column, and the corresponding anchor, respectively.

3. The substructure of claim 1, wherein each buoy comprises two opposing cone- shaped elements joined together at a mid-region of the buoy, and wherein each cone-shaped element is hollow.

4. The substructure of claim 1, wherein each articulating joint interconnecting adjacent buoys comprises a structural element having spherical bearing surfaces arranged to mate with corresponding spherical bearing surfaces provided at apex regions of cone-shaped elements of the respective buoys, the spherical bearing- 19 - surfaces being arranged so that a center of rotation is located at a center of the structural element.

5. The substructure of claim 1, wherein each first sling, each second sling, and each third sling connected to a respective articulating joint is arranged such that a tension line of action of each first sling, a tension line of action of each second sling, and a tension line of action of each third sling intersect at a point located at a center of the structural element of the respective articulating joint.

6. The substructure of claim 1, wherein the material is configured to resist mainly compressive loading, like a material that comprises concrete.

7. The substructure of claim 1, wherein the plurality of first slings is arranged in groups of one or more slings and the plurality of second slings is arranged in groups of one or more slings, each group of the plurality of first slings and each group of the plurality of second slings being arranged so that the slings of each group share tensile load and so that, in the event one sling of the group fails, the other sling of the group is configured to assume the tensile load carried by the failed sling.

8. The substructure of claim 1, wherein the plurality of first slings is pre-tensioned so that the plurality of first slings is configured to resist heeling of the turbine tower by exerting a restoring moment.

9. The substructure of claim 1, wherein the articulating joints are configured such that the structural stiffness of the ring configuration of buoys is determined primarily by the stiffness of the plurality of first slings and the plurality of second slings and the plurality of third slings.

10. The substructure of claim 1, wherein each buoy is connected at its ends to the respective articulating joints a manner that permits rotational freedom at buoy- 20 - ends, thereby reducing bending moments induced by buoyancy and hydrodynamic forces.

11. The substructure of claim 1, wherein each anchor is configured to attach and secure an end of a respective third sling to a seabed, the tension in the third sling being generated by the buoyant forces acting on the substructure.

12. The substructure of claim 1, wherein each buoy is configured with an external volume selected such that the combined buoyancy of the plurality of buoys provides a buoyancy force being sufficient to support the weight of the turbine tower and the substructure.

13. The substructure of claim 3, wherein the cone-shaped elements of each buoy form a double-cone geometry having a maximum diameter at the mid-region, the maximum diameter configured to provide an increased moment of inertia of a cross-section of the buoy, and reducing bending stress arising from transverse buoyancy forces and hydrodynamic loading.

14. A method of installing a floating substructure for supporting an offshore wind turbine, comprising: a) lowering a plurality of support columns or part of the support column into a body of water to a position, in which the plurality of support columns extend from a water surface toward a seabed, wherein each support column of the plurality of support columns comprises a temporary buoy, an articulating joint releasably attached to the temporary buoy, a first sling, a second sling, a third sling, and an anchor, wherein the first sling, the second sling, and the third sling are connected to the articulating joint, and wherein the anchor is connected to the articulating joint by the third sling, with the temporary buoy located above the articulation joint and the anchor disposed on the seabed; positioning a plurality of buoys in a ring configuration, each buoy from the plurality of buoys being positioned- 21 - between adjacent support columns, and interconnecting adjacent buoys using the articulating joints of corresponding support columns; b) positioning a central column within the ring configuration; c) connecting a plurality of second slings between a distal region of the central column and corresponding articulating joints; and d) connecting a plurality of first slings between a proximal region of the central column and corresponding articulating joints.

15. The method of claim 14, comprising assembling each support column or part of the support column of the plurality of support columns prior to lowering the plurality of support columns into the body of water.

16. The method of claim 14, comprising installing a bridge member between two support columns to temporarily ensure the attachments between the buoys and the articulating joint during assembly.

17. The method of claim 14, comprising removing the temporary buoys at the end of the installation process.

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