The present invention relates generally to an anchoring system that anchors an object to the floor of a body of water, and more particularly to an anchoring system that anchors a base to which a wind turbine is connected, such as a submersible, buoyant raft, to thereby secure the wind turbine to the floor of the body of water.
In view of the growing demand for renewable energy as well as the fact that stronger winds prevail offshore in comparison to those onshore, offshore wind farms have a great potential to significantly grow in the coming years. Although an offshore wind farm is more productive than its onshore, terrestrial counterpart, one of its main constraints of offshore wind farms is the depth limit of the ocean floor to which the wind turbines of the wind farms are connected.
Existing technologies that anchor wind turbines to the ocean floor provide an economical solution at offshore locations where the water depth is not greater than about 30 meters. A number of research and development projects have tried to implement various technologies in order to develop a floating raft as a basis for an offshore, large span wind turbine. However, all current solutions known to the inventor are either not effective or not cost effective.
An anchoring system for anchoring an object to a bottom floor of a body of water includes a weighted portion, an explosive charge arranged on the weighted portion and that, when initiated, causes a concentrated jet of explosive product produced by the explosion of the explosive charge, such as plasma, to be directed in a direction downward from the weighted portion, and a pole arranged on the weighted portion and arranged to move relative to the weighted portion. The anchoring system also includes a penetration system arranged partly on the weighted portion and that moves the pole in the downward direction after initiation of the explosive charge at least partly into an area in which the concentrated jet is directed. A connecting system couples the weighted portion to the object being anchored, e.g., a rope from the pole to a base that supports a wind turbine. In use, when the weighted portion rests on the floor of the body of water and the explosive charge is initiated, the concentrated jet creates an initial penetration into an area of the floor of the body of water and the penetration system is then activated to move the pole into the pre-penetrated area to cause the pole to penetrate into the pre-penetrated area and be secured in the floor of the body of water.
Various penetration systems are contemplated including ones that use rotation of the pole into the pre-penetrated area, an additional explosive to force the pole into the pre-penetrated area, a linear pushing optionally with a vibration component and hammering of the pole into the pre-penetrated area.
Also disclosed is a related anchoring arrangement wherein a plurality of the anchoring systems are used to anchor a single object to the floor of the body of water, and a method for anchoring an object to a bottom floor of a body of water using the above structure.
Other and further objects, advantages and features of the present invention will be understood by reference to the following specification in conjunction with the annexed drawings, wherein like parts have been given like numbers.
The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals identify like elements, and wherein:
Referring to the accompanying drawings wherein the same reference numerals designate the same or similar elements, an anchoring system in accordance with the invention generally comprises a weighted portion that will rest on the floor of a body of water, e.g., the ocean floor, an explosive charge that, when initiated, causes a pre-penetration of explosive product, e.g., plasma, into the ocean bed, an anchoring pole or penetrating pole that is forced into the pre-penetrated ocean bed and thereby penetrate the pre-penetrated portion of the ocean bed, and a connecting system that couples the anchoring pole or penetrating pole to an object to be anchored, e.g., a buoyant, submerged raft or other base that supports a wind turbine.
More specifically, in a first embodiment of the invention shown in
Anchoring system 10 also includes an explosive charge arrangement 16 situated at the bottom of the weighted portion 12. As shown, the explosive charge arrangement 16 has an angular conical shape with a hollowed conical portion that has been found, when initiated, to provide advantageous penetration into the ocean floor, or any other type of surface. In this case, the lower surface of the weighted portion 12 is provided with a conical depression and the explosive charge arrangement 16 is then placed therein, e.g., when fabricating the anchoring system prior to placement at the usage site.
The explosive may be virtually any type of known explosive that can be shaped or formed to achieve the objective of creating a pre-penetration area in the ocean bed. That is, different explosives may be used in the invention so long as they provide, when initiated, a concentrated jet of explosive product that penetrates the ocean bed to facilitate a subsequent penetration of the anchoring pole or penetrating pole. Some explosives, when formed as hollow charge explosives, can create a concentrated jet of plasma that can be implemented in the invention and cause the pre-penetration area to reach a depth of about 10 meters, which is sufficient to facilitate the subsequent penetration of the anchoring or penetration pole.
Anchoring system 10 also includes an anchoring pole 18 arranged above the explosive charge arrangement 16 and in an elongate hole 20 in the weighted portion 12 that extends to an opening in the top surface of the weighted portion 12. Anchoring pole 18 includes a drill head 22 and an elongate portion 24, and is situated at least partially in the elongate hole 20 in the weighted portion 12. Optionally, a holding and guiding cylinder may be interposed in the elongate hole 20 between the weighted portion 12 and the elongate portion 24 of the anchoring pole 18.
Elongate portion 24 optionally includes one or more axially extending slots 26 therein, as shown in
A rotation mechanism is coupled to the anchoring pole 18 to rotate the anchoring pole 18 and thus the drill head 22. In the illustrated embodiment, this rotation mechanism comprises a motor 28 and a transmission mechanism, e.g., one or more gears 30 coupled to the anchoring pole 18, that converts output of the motor 28 into rotation of the anchoring pole 18 and the drill head 22 thereof. Motor 28 may be an air motor that is driven by compressed air from a tank attached to the weighted portion 12 (not shown) or by air pressure supply from the crane boat. Instead of compressed air, other fluids may be used, including compressed water.
Conversion of the output of motor 28 into rotation of the anchoring pole 18 may be obtained by shaping an aperture in the gear 30 as a non-circular form, e.g., rectangular, square or hexagonal, and providing the part of the elongate portion that is accommodated in to the gear 30 with a corresponding shape. This fitness allows the gear 30 to rotationally drive the anchoring pole 18 and thus enables the anchoring pole 18 to move linearly forward (downward in to the ocean floor 8) during the drilling process.
The anchoring system also includes a connecting system, such as one including a rope 32, that connects to an object sought to be anchored to the ocean floor 8. When used for a wind turbine, this object may be a support base for the turbine, such as a submersible, buoyant raft (shown in
At the end of the rope 32 in the anchoring system, a conically shaped wedge element 34 is provided and is situated in an interior of the elongate portion 24 of the anchoring pole 18. The conical shape of the wedge element 34 enables the outer circumference of the bottom edge region of the elongate portion 24 of the anchoring pole 18 to increase, e.g., an increase in its diameter if the bottom edge region is circular, when the rope 32 is pulled upward. The diameter increase is aided by the axially extending slots 26 when present. This pulling occurs at the end of the anchoring process, as described below.
A non-limiting, exemplifying use of the anchoring system 10 shown in
Once at the selected location, the anchoring system 10 is lowered down to its desired anchoring site on the ocean floor 8 via ropes 36. At this stage, the rope 32 is tension-free.
Once at the desired anchoring site on the ocean floor 8, the explosive charge arrangement 16 is initiated and the hollow charge ignites and a concentrated jet of explosive product penetrates the ocean floor 8 causing formation of a pre-penetration area 38 in the ocean bed (see
After the drilling is completed and the drill head 22 is at a desired depth in the pre-penetration area 38, the rope 32 is pulled upward and tightened causing the wedge element 34 to be pulled upward. This causes an increase in the circumference of the bottom edge region of the elongate portion 24 of the anchoring pole 18 and thus the elongate portion 24 is forced against the peripheral walls 40 of the pre-penetration area 38. This pressing force thereby secures the elongate portion 24 of the anchoring pole 18 to the ocean bed and thus strengthens the anchoring force provided by the anchoring system 10. The anchoring process for the anchoring system 10 is now complete.
The upper end region of rope 32 is then tightened to the object, e.g., a raft or other base to which a wind turbine is secured. The same raft may be secured by other anchoring systems and once all anchoring systems are anchored to the ocean floor and their ropes to the raft tightened, the ropes are shortened to force the raft to be submerged under the ocean surface at a desired submersion depth.
Submerging the raft provides significant advantages when used as a support for a wind turbine. Among others, a submerged raft is less subject to surface conditions of the body of water when it is submerged, i.e., it is not substantially affected by waves and atmospheric conditions at the ocean surface, and therefore provides increased stability. The depth to which the raft should be submerged can vary on the operational and constructional conditions and may be, for example, about 30 feet or more below the water surface.
Anchoring system 42 also includes a barrel 48 fixed to the weighted portion 44, a penetrating pole 50 arranged in a hollow interior of the barrel 48 and a secondary explosive charge arrangement 52 arranged in a compartment in the barrel 48 that communicates with the top of the penetrating pole 50 or a space above the penetrating pole 50. Barrel 48 may be cylindrical and define a cylindrical hollow interior. Further, at the lower end region, the peripheral walls of the barrel 48 taper inward to form a truncated conical surface 54 such that the diameter of the upper portion of the interior of the barrel 48 is larger than the diameter of the lower portion. The penetrating pole 50 is preferably constructed with a unique shape wherein it has an upper portion 56 that fits tightly against the inner surface defining the interior space of the barrel 48, a penetrating portion 58 that penetrates into the ocean bed and a tapering portion 60 therebetween. The penetrating portion 58 includes ribs 62 on an outer surface thereof which serve to increase the anchoring force.
The barrel 48 is preferably embedded in the weighted portion 44 by pouring concrete around the lower portion of the barrel 48, e.g., using a mold and pouring the wet concrete around the barrel 48 so that when the concrete solidifies, the weighted portion 44 and barrel 48 are integrated with one another. Barrel 48 may be made from steel or another comparable rigid material.
A non-limiting, exemplifying use of the anchoring system 42 shown in
Once at the selected location, the anchoring system 42 is lowered down to its desired anchoring site on the ocean floor 8. At this stage, a rope 64 connecting the barrel 48 to the object being anchored, e.g., a raft for a wind turbine, is tension-free. Once at the desired anchoring site on the ocean floor 8, the explosive charge arrangement 46 is initiated, in a manner known to those skilled in the art, and the hollow charge ignites and a concentrated jet produced by the exploding primary explosive charge arrangement 46, represented as 66, penetrates the ocean floor 8 causing the formation of a pre-penetration area in the ocean bed. Thereafter, the secondary explosive charge arrangement 52 is initiated, in a manner known to those skilled in the art. Initiation of secondary explosive charge arrangement 52 may occur immediately after initiation of the primary explosive charge arrangement 46, the exact time differential may be determined by routine experimentation.
Initiation of the secondary explosive charge arrangement 52 creates high pressure above or behind the penetrating pole 50 and thereby causes the penetrating pole 50 to be urged downward through the interior of the barrel 48 with the penetrating portion 58 thereof being urged into the pre-penetration area formed by the concentrated jet produced by the exploding primary explosive charge arrangement 46. The downward movement of the penetrating pole 50 stops when the tapering portion 60 abuts against the truncated conical surface 54 of the barrel 48. Since there is little or no resistance to the forcing of the penetrating portion 58 of the penetrating pole 50 into the ocean bed as a result of the formation of the pre-penetration area by the concentrated jet of exploding explosive charge arrangement 46, anchoring of the penetrating pole 50 to the ocean bed can take a little as a few minutes. The ribs 62 improve the anchoring effect.
Another improvement to the anchoring effect may be obtained by angling the direction of penetration of the penetrating pole 50 into the ocean bed to be other than perpendicular to the ocean bed. Such a penetration angle may depend on the angle of the rope between the anchoring system and the object being anchored thereby. A possible range of angles is from about 20° to about 70°, more particularly from about 30° to about 60°.
The upper end region of rope 64 is then tightened to the object, e.g., a raft or other base to which a wind turbine is secured. The same raft may be secured by other anchoring systems and once all anchoring systems are anchored to the ocean floor and their ropes to the raft tightened, the ropes are shortened to force the raft to be submerged under the ocean surface at a desired submersion depth.
A common feature of the embodiments described above is initiation of an explosive charge arrangement to cause a concentrated jet of explosive product produced by the exploding explosive charge arrangement to penetrate the ocean floor to facilitate subsequent movement of an anchoring member into the pre-penetrated ocean bed, i.e., penetration of the anchoring member into the ocean bed. This subsequent movement of the anchoring member may be obtained via rotation as in the embodiment shown in
Furthermore, each of the anchoring systems of the present invention can include more than one anchoring pole or penetrating pole. Each pole can be placed, instead of perpendicular to the ocean floor as shown in
Ropes 74 connect the raft 70 to the anchoring systems 68, although other connecting members or connecting elements may be used. Winches 76 are mounted on the raft 70 to tighten and shorten the ropes 74, i.e., one winch 76 may be associated with each rope 74, and thereby control the ability to submerge the raft 70 and the level to which the raft 70 is submerged. Raft 70 optionally includes inflatable, flexible elements 78 therein. Raft 70 may have a rectangular shape and be made of fiberglass profiles, fiber glass screws and Kevlar ropes that are constructed together, although this shape and constructions are not limiting.
A tower 80 is arranged on the raft 70 and extends from below surface level to above surface level and a plate 82 is arranged on the tower 80 above the surface level. An electrically operated winch 84 is arranged in the plate 82 and controls a length of a rope 86 that connects to the airborne wind turbine system 88. Rope 86 may be made of KEVLAR® or a comparable material. One or more inflatable elements 90, e.g., a wing balloon, are also connected to the airborne wind turbine system 88. Wing balloon is a lighter-than-air element with an aerodynamic shape that provides a lifting force of the wind turbine system 88. A plurality of towers 80 can be supported by the raft 70.
Other types of wind turbine arrangements may also be coupled to the raft 70. For example,
Referring now to
With the foregoing structure, the present invention provides an anchoring system and method that eliminate the depth constraint for anchoring offshore wind turbines and thereby enable the effective development of offshore wind farms at any ocean depth. Moreover, the present invention provides an economical viable solution that addresses the two core flaws the prevail in the development of a floating raft as a basis for anchoring wind turbines, namely the construction of an anchoring system and the cost and survivability of the raft in ocean conditions.
Furthermore, the system of the present invention provides a stable basis or platform for offshore wind turbines that is isolated from weather conditions and ocean surface conditions such as waves. The prefabricated anchoring systems provide adequate forces to submerge a floating raft that can then be used as a stable and isolated basis for the wind turbines. Instead of supporting wind turbines, the anchoring systems and raft coupled thereto may be used in other industries such as oil drilling and processing, drilling rafts and the like.
It is to be understood that the present invention is not limited to the embodiments described above, but includes any and all embodiments within the scope of the following claims. While the invention has been described above with respect to specific apparatus and specific implementations, it should be clear that various modifications and alterations can be made, and various features of one embodiment can be included in other embodiments, within the scope of the present invention.
This application claims priority of U.S. provisional patent application Ser. No. 61/179,110 filed May 18, 2009, which is incorporated by reference herein.
Number | Date | Country | |
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61179110 | May 2009 | US |