Technical field

[0001 ] The present invention relates generally to floating platform and an energy producing plant comprising such a floating platform. The energy producing plant comprises at one or several energy producing systems, for example wind power generators, attached to the floating platform.

Background

[0002] Utilizing renewable energy sources, such as winds and ocean waves and currents, for creating electric power is becoming a more and more preferred energy producing system because it does not evaporate CO2 into the atmosphere.

[0003] Most energy producing plants today utilizes only one renewable energy source, mainly wind. These energy producing plants comprise several wind power units placed as separate units on land or in the ocean. When placed in the ocean the units normally are moulded to the ocean bottom with concrete pillars or steel foundations. This requires relatively shallow water and is therefore a placement used close to shore, thus normally close to habited or recreational areas. This placement is not desirable from an environmental view.

[0004] To build wind power plants further out to sea meets the problem of a usual greater depth, but also the practical economical problem of supervision and maintenance. Due to the fact that wind power plants up to today uses separate wind generator units, a placement further out to sea quickly becomes

uneconomical.

[0005] The principle of placing an energy producing plant out in the ocean instead of onshore has the advantage of being exposed to normally more frequent wind and higher wind speeds. An energy producing plant placed out on the ocean can also be used as a platform for other types of energy converting systems, such as for example wave and sun energy converters. [0006] However, an energy producing plant placed out on the ocean is exposed to strong wind and harsh weather. Thus, it is necessary that all components of the plant are durable and that the construction itself is rigid. It is of big importance that supervision and maintenance work is easy to perform.

[0007] In the applicant's previous application WO201 1071444A1 such an energy producing plant is described. This plant is a floating platform comprising a frame work constructed of hollow pipes/ beams connected by nodes surrounding a center node. On the nodes wind generators may be placed. Each pipe/beam is sealed in its respective end and forms separate floating parts adapted to be connected to the nodes. Further, the volumes within each floating part, i.e. beams and nodes, are connected to each other. I.e. nodes and pipes/beams are connected so that the pipes/beams form transport paths between the nodes. The space in these parts can be used as transport paths, workshops, storage rooms, accommodations or provide space for other functions.

[0008] In JP2007160965A another floating platform is disclosed comprising separate radially arranged floating parts connected to each other in a central point. Tensile forces are created between each floating part by a tension part provided between the floating parts. Using this construction decreases the forces acting on the platform, thus makes it possible to use construction details of a smaller dimension.

[0009] Even though the tension parts used in the Japanese application decreases the external forces on the platform, the extreme conditions out at sea makes damage and wear of the platform components inevitable. It is therefore desirable to create a platform where parts of the platform can be exchanged or repaired still out at its sea based location.

[0010] The large sea based platform may also function as a sea harbor. It is also desirable to be able to directly reach the center node with a ship or other water borne vessels. The transport to and from the plant and its maintenance may then be simplified. A mooring position within the framework it also preferable from a safety point of view, since the water may be calmer within the structure. Summary of invention

[001 1 ] An object of the present solution is to create a floating platform which can be mounted far out in the ocean and which may be used as a platform for an energy producing plant comprising one or several energy converting systems, for example a plurality of wind power generators attached to the platform. The floating platform shall be easy to assemble, repair and maintain and may also function as a floating harbor. This floating platform is described in claim 1 .

[0012] The solution relates to a floating platform comprising at least three floating or semi-submersible peripheral units and a floating or semi-submersible central unit. Each peripheral unit is arranged connected to the central unit by at least one, in a substantially radial direction arranged, radial connection member and connected to the adjacent peripheral units by at least one peripheral connection member. The solution may be characterized in that at least one propulsion device is arranged on each submersible peripheral unit.

[0013] When using a propulsion device arranged on each peripheral unit it is possible to keep each peripheral unit in position in relation to the other even if the peripheral connection members are broken or removed.

[0014] In one embodiment the at least one propulsion device is adapted to make the peripheral units maneuverable in an essentially horizontal direction and in another embodiment the least one propulsion device is adapted to make the peripheral units maneuverable in an essentially vertical direction.

[0015] If the propulsion device is a propeller or jet engine of any kind arranged in a horizontal, vertical or adjustable position it is possible to control the motion of the peripheral unit. The units may be arranged to move in an essentially horizontal direction towards each other and/or in an essentially vertical direction to position each unit in an essentially equal horizontal position. Thus, the propulsion devices may also be used to help positioning the peripheral units in relation to each other and the nodes when the platform is assembled.

[0016] In another embodiment the propulsion device is a thruster. [0017] A thruster is a thoroughly tested system for controlling the position of stern or bow of a spacecraft or watercraft. It may also be used for station keeping of the craft. A thruster may therefore be a suitable propulsion device for the peripheral unit. If the thruster is arranged offset from the centre of gravity it may be possible use a stationary vertical propeller to control the position of the peripheral units in relation to each other by rotation of each peripheral unit.

[0018] In another embodiment the peripheral connection members are elastic or semi-elastic or at least one of the peripheral connection members is in at least one end attached to the respective peripheral unit via an articulated joint. This, in order to allow the floating peripheral units to move in relation to each other.

[0019] The peripheral connection member is constructed to allow movement between the adjacent floating peripheral units. When a slight movement is allowed, the forces in the structure and its attachment points are decreased. If a movement is allowed it is also possible to detach the peripheral floating units from each other without creating an increased tension in the structure.

[0020] In order to allow a relative movement between the separate peripheral units, either the peripheral connection member itself is flexible, for example by using a rope or similar, or the distal ends of the peripheral connection member can be attached articulately to the respective peripheral unit, preferably with a joint arrangement.

[0021 ] In another embodiment the peripheral connection member is an elongated object variable in length constructed to create a tension force pulling the floating peripheral units towards each other.

[0022] When using an elongated object the peripheral units may be arranged in a pattern creating a hexagon shape with one center node. This creates a natural optimized balanced structure. However, other shapes are of course also possible. The variation in length is either possible by using an elastic material stretching and retracting in length and/or by using a separate length adjusting device connected to the peripheral connection member. [0023] In another embodiment, the peripheral connection member is a flexible object, such as a wire, cord, cable, rope or other similar elongated flexible object.

[0024] In another embodiment, a length adjusting arrangement is connected to the peripheral connection member, which is adapted to adjust the length of peripheral connection member.

[0025] In another embodiment, the connection member is a rigid beam or pipe.

[0026] When the peripheral connection member is a rigid beam it is in at least one end attached to the respective adjacent peripheral unit via an articulated joint or similar arrangement allowing a pivotal movement between two of the peripheral units around an essentially vertical axis.

[0027] In another embodiment, least one of the peripheral connection members is in at least one end detachably connected to the respective adjacent peripheral unit.

[0028] The invention further relates to an energy producing plant comprising; a floating platform according to the above described, an energy producing system and an anchoring system arranged to anchor the floating platform to the bottom of an ocean.

[0029] The energy producing system which is used may be at least one of; a wind power generator, wave power generator, sun cell or wind shovels.

[0030] Each floating peripheral unit of the energy producing plant may also comprise at least one semi-submersible node on which a wind power generator is mounted.

[0031 ] Using the inventive platform as a base for an energy producing plant is particularly of interest since the platform is very well suited for this application, due to the fact that it can operate independent of depth and far out on the open ocean. The platform can be firmly anchored at the bottom by the anchoring system.

Preferably the anchoring system is attached to the central unit, thus enabling the entire platform to rotate and automatically adjust in line with the wind and/ or water current direction so that the energy producing systems are placed in an optimum position for energy extraction. When wind power generators are used they can be placed on the semi-submersible nodes of the platform, thus enabling access to the generator housing through the hollow interior of the nodes and the connection members.

Brief description of the drawings

[0032] The invention is now described, by way of example, with reference to the accompanying drawings, in which:

[0033] Fig. 1 a disclose a top view of a first embodiment of the invention

[0034] Fig. 1 b disclose a top view of a second embodiment of the invention

[0035] Fig. 2 and 3 disclose a top and a perspective view of a third embodiment of the invention.

[0036] Fig. 4 and 5 disclose detail views of a first and second embodiment of the propulsion device

[0037] Observe that all embodiments or part of an embodiment can be combined in any way.

Description of embodiments

[0038] Embodiments will now be described in more detail with reference to the accompanying drawings. All examples herein should be seen as part of the general description and therefore possible to combine in any way in general terms. Again, individual features of the various embodiments and methods may be combined or exchanged unless such combination or exchange is clearly

contradictory to the overall function of the floating platform.

[0039] When the expressions horizontal and vertical are used they shall be interpreted as a first direction essentially parallel to the average sea water level and a second direction perpendicular to the first direction. [0040] One first embodiment of the floating platform used as an energy producing plant is disclosed in figure 1 a. Figure 1 a discloses a floating platform 1 comprising six floating or semi-submersible peripheral units 2 arranged detachably connected to a central floating or semi-submersible unit 3. Each floating peripheral unit 2 is in this embodiment a semi-submersible node 4 on which a wind power generator WG is mounted. However, it is also possible to arrange other types of energy converting systems on the platform. Connected to each peripheral floating unit 2 is at least one propulsion device 1 1 . The propulsion device 1 1 may for example be attached to the floating unit on the horizontal side of a node 4 or below the node, i.e. at its bottom surface. Other positions, such as attachment to the later described node connections members 9, are also possible. When using a propulsion device arranged on each peripheral unit it is possible to keep each peripheral unit in position in relation to the other even if the peripheral connection members are broken or removed. With the propulsion devices 1 1 it is also possible to move the peripheral units 2 in at least the horizontal and vertical directions, and possible all directions there between. Thus, the propulsion devices 1 1 may also be used to help position and line up the peripheral units in relation to each other and to the connection members 5, 6 when the platform is assembled.

[0041 ] Between the peripheral units 2 and the central unit 3 a connection member 5 is arranged protruding in a substantially radial direction from the central unit 3. The connection between the peripheral and central units 2, 3 and the connection members 5, can be detachable by a connection coupling 10 or rigid, i.e. the connections member can be welded or in any other way firmly attached to the peripheral and/or central units 2, 3. In the embodiment according to figure 1 a, the connection member 5 is in its proximal end 5a attached to the central unit 3 by a detachable connection coupling 10, enabling relative movement between the central and peripheral units 3, 2, and in its distal end 5b it is firmly attached to the peripheral units 2.

[0042] The floating or semi-submersible peripheral units 2 are connected to each other by a detachable peripheral connection member 6 allowing each floating unit to move in relation to the other at least in a direction substantially parallel to an elongation direction of the peripheral connection member 6. The detachment/attachment point may be between the floating units and one or both ends of the connection member 6. The peripheral connection members 6 are connecting one node 4 of each floating peripheral unit 2 with a node 4 of another adjacent floating peripheral unit 2 and are constructed to allow movement between the peripheral units 2 and may also be used to create a tension force pulling the adjacent floating peripheral units 2 towards each other. Thus, the peripheral connection member 6 is an elongated object variable in length either by means of usage of an elastic material stretching and retracting in length and/or by using a separate length adjusting device 15. When shortening the peripheral connection member the peripheral units 2 are pulled together pre-tensioning the entire platform. The elastic properties of the peripheral connection member itself may absorb / dampen the forces created by the waves. When the peripheral connection members 6 are detached in at least one detachment/attachment point it is possible to use the inner space of the platform as a safe harbor for any sea vessel or ship 12, see figure 2. Thus, the central node 3 and/or the radially arranged connection members 5 may also function as moorage protected from the surrounding ocean.

[0043] In figures 1 a, 1 b, 2, 3 and 4, the peripheral connection member 6 is a flexible wire, cord, cable, rope or similar, but it can also be a not disclosed length adjustable mechanical arrangement. It is for example possible to use a mechanical arrangement comprising two parts arranged telescopically moveable in relation to each other. If such a mechanical arrangement is used the opening of the entrance to the inner space may be simplified.

[0044] In some embodiments the connection member 6 may be a rigid beam or pipe. If a rigid connection device is used it must in at least one end be attached to the respective peripheral unit via an articulated joint 8 allowing a pivotal movement between adjacent peripheral units 5 around an essentially vertical axis. The pipe/beam may also be a hollow arrangement closed from the surroundings, as the connection members 5, 9 are described.

[0045] To allow a relative movement between the separate peripheral units 2, either the peripheral connection member 6 itself is flexible, for example by using a rope, or if a rigid mechanical arrangement is used, its distal ends can be attached to the respective peripheral unit 2 with an articulated joint 8.

[0046] Figure 1 b discloses a second embodiment of the invention. Here at least two of the peripheral floating units have the form of nodes 4a, 4b; 4d, 4e, connected to each other by a node connecting connection member 9, forming an elongated peripheral floating unit 2a, 2b. The nodes 4a, 4b; 4d, 4e act as a connection point for at least one peripheral connection member 6 and at least one connection member 5, 9. Connected to each peripheral floating unit 2 is at least one propulsion device 1 1 . The propulsion device 1 1 may be attached to the floating unit on the horizontal side of a node 4 or below the node, i.e. at its bottom surface. The elongated peripheral floating units 2a, 2b comprises one propulsion device 1 1 arranged at one of the two connected nodes 4a, 4b; 4e, 4d, i.e. off center from the center of gravity of the floating units. The entire elongated peripheral units 2a, 2b can be seen as a watercraft and its movement in the water may be controlled accordingly, by for example a thruster as a propulsion device.

[0047] The node connection member 9 and the nodes 4a, 4b; 4d, 4e together form the peripheral floating node units 2a, 2b. The peripheral floating node units 2a, 2b are attached to the central unit 3 by at least one connection member 5 arranged in a substantially radial direction from the central unit 3. The connection member 5 is in its proximal and distal ends 5a, 5b attached to the central unit 3 by a connection coupling 10, enabling additional relative movement between the central and peripheral units 3, 2, see figures 4, 5a and 5b.

[0048] In the embodiment shown in figure 1 b, the distally arranged attachment couplings 10 are attaching the connection members 5 with the respective nodes 4a, 4b; 4d. However, it is also possible to attach the radially arranged connection member 5 directly to the node connection member 9. See figure 2. Preferably, the attachment coupling 10 allows a movement between the connection member 5 and the node 4 and/or the node connection member 9. For example a pivoting movement around an essentially horizontal axis. [0049] Each peripheral floating unit 2a, 2b is connected to the remaining floating units 2 by a peripheral connection member 6 allowing each peripheral floating unit to move in relation to the other in a direction substantially parallel to an elongation direction of the peripheral connection member 6. The peripheral connection members 6 are connecting one node 4a, 4b; 4d, 4e of each floating peripheral unit 2a, 2b with an adjacent node 4 of another adjacent floating peripheral unit 2 and are constructed to allow movement between the nodes 4 and to create a tension force pulling the floating peripheral units 2 towards each other, as described in the description of figure 1 a. It is also possible to exchange one or both of the floating peripheral unit 2 with floating peripheral node units comprising more than one node connected by connection members, as described in figure 2 and 3.

[0050] The plant in figures 1 a and 1 b is preferably in the shape of a hexagon with one center node 4. However, other shapes are also possible. The connection members 5 are preferably one or more hollow steel beams or pipes. The radially arranged connection members 5 are having a length of approximately 100-300 meters while the node connecting connection members 9 are having a length of approximately 50-100 meters. The connection members 5, 9 can be circular, rectangular or have any other suitable shape. The connection members can be arranged floating on or partly or fully submerged under the water surface or may comprise two or more sets of, in the vertical direction, essentially parallel connection members. The semi-submersible nodes 4 are for example a cylinder shaped, partly submerged, arrangement, approximately 10-20 meters in diameter and approximately 20-30 meters high.

[0051 ] Figures 2 and 3 disclose a third embodiment of the invention. Here the platform comprises a central floating node unit 3 and four floating peripheral units 2a, 2b, 2c, 2d, each comprising at least three semi-submersible nodes 4 connected to each other by a set of connection members 9. At least one propulsion device 1 1 is arranged on each peripheral unit 2a, 2b, 2c, 2d. On the larger peripheral units 2a and 2c, where several nodes are connected, two or more propulsion devices 1 1 are preferably used. The separate connection members 9 may be arranged floating on or partly or fully submerged under the water surface or may comprise two sets of, in the vertical direction, essentially parallel

connection members. The central unit 3 is in this embodiment assembled by three connected nodes 4. The central node 3' in the central unit 3 may act as a hub around which the whole platform 1 can rotate.

[0052] The set of connection members 9 and the nodes 4 together form a rigid and stable floating unit 2a, 2b, 2c, 2d. The floating units 2b and 2d comprise more than three nodes and all nodes are connected with a connection member 5, 9. Assembling more than three nodes into a floating unit creates a larger platform on which several energy converting system/wind generators can be mounted. It is also possible to mount additional wind generators of different size or other energy producing units such as wave energy converters directly on the connection members 5, 9.

[0053] The peripheral floating node units 2a, 2b, 2c, 2d are connected with the central unit 3 with at least one radially arranged connection member 5. In each end 5a, 5b of the connection member 5, a connection coupling 10 is arranged which allow certain pivotal moment between the connection member 5 and the central and peripheral units 3, 2a, 2b, 2c, 2d. Each peripheral floating node unit 2a, 2b, 2c, 2d are connected to the adjacent node units by a detachable peripheral connection member 6 allowing each peripheral floating node unit to be detached from the adjacent floating unit and to move in relation to the other, as described above.

[0054] Each floating unit, both central and peripheral, 3, 2a, 2b, 2c, 2d is easily towed to the predetermined location out in the ocean and assembled on site. The assembly of the floating unit is simplified by using the propulsion devices 1 1 since they may be used to position and line up the different part in relation to each other before they are assembled.

[0055] The central node 3 and/or the connection members 5 may also function as a safe harbor for ships 12 protected from the surrounding ocean by the detachable peripheral connections members 6 and the peripheral units 2a, 2b, 2c, 2d. [0056] The connection members 5 may be sealed in each end 5a, 5b forming a closed air filled unit which can float on water and be easier towed to the location where the energy producing unit shall be build. A sealable opening 13 may be arranged through the connection coupling 10. Thus, a possible transport route between the floating units through the inner volume of the connection members and nodes is created.

[0057] Consequently, besides creating strength and buoyancy to the

construction, the connection members 5 can also be used as connection paths, accommodation, workshops and storage rooms. It is also possible to arrange a lifting crane or similar device on the connection members 5 in order to perform assembly, care and maintenance of the plant. The lifting crane and other large details, such as spare parts, may be transported between the wind generator towers on a track system arranged on the top surface of the connection members 5.

[0058] Due to the floating properties of the floating unit, it can operate independent of the depth. It can be anchored at the bottom, for example with an anchoring system 14 used for large marinas. The anchoring system 14 emanates from the rotatable hub 3' with for example three to eight laterally extending anchoring attachments. The central floating unit is through the anchoring attachments firmly anchored at the bottom and the entire construction can rotate around the hub in the central floating unit. Thus, the entire construction is able to rotate freely 360 degrees and automatically adjust in line with the wind direction so that the firmly attached wind propellers always are placed in an optimum position.

[0059] The floating platform according to the invention can also be

supplemented and optimized with other energy producing systems, such as for example wave power generators WPG, sun cells and vertical or horizontal wind shovels rotating around its own axis, thus can use the incoming wind blowing below the lowest position of the propellers. Furthermore, it is possible to utilize the vertical movements in the sea of the entire platform for energy extraction. If wave power generators WPG are used they are preferably placed along the outside of the plant on the side directed towards the waves. [0060] In figure 4 it is disclosed a first embodiment of the propulsion device 1 1 . The propulsion device 1 1 is here attached to the vertical wall of a node 4, but it is of course also possible to attach the propulsion device 1 1 on any other part of the peripheral unit such as for example any of the node connecting connection members 9. The propulsion device 1 1 is in this embodiment a vertically arranged thruster connected to an attachment unit 13 comprising for example the drive unit creating the rotation of the thruster. The propulsion device may also be a separate propeller or jet engine of any kind. It is also possible to arrange the propulsion device 1 1 in a vertical position or to make the device 1 1 rotatable in relation to the peripheral unit around an essentially vertical or horizontal axis. This makes it possible to control the motion of the peripheral units 2a-2d in a horizontal and vertical direction and also in all directions there between. Thus, the propulsion devices may also be used to help positioning the peripheral units in relation to each other and the nodes when the platform is assembled.

[0061 ] In figure 5 a second embodiment of the propulsion device 1 1 is shown. The propulsion device 1 1 , in this case a vertically arranged thruster, is here directly attached below the node 4, i.e. at its bottom surface. The entire thruster may be rotatable around a vertical rotation axis A1 . In this embodiment the drive unit creating the rotation of the thruster may for example be arranged inside the node 4.