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Title:
METHOD AND APPARATUS FOR DEPLOYING TIDE DRIVEN POWER GENERATORS
Document Type and Number:
WIPO Patent Application WO/2017/045030
Kind Code:
A1
Abstract:
A tidal turbine support structure is disclosed. The structure is provided with two buoyancy conditions, one which permits floating of the structure and one which causes the structure to sink to a desired depth. This is achieved through the provision of buoyancy chambers which may be selectively filled with air or water.

Inventors:
BROWN PHIL (AU)
Application Number:
PCT/AU2016/050866
Publication Date:
March 23, 2017
Filing Date:
September 16, 2016
Export Citation:
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Assignee:
WORLEYPARSONS SERVICES PTY LTD (AU)
International Classes:
E02B9/08; E02B17/08; F03B13/26; F03B17/06
Domestic Patent References:
WO2014205603A12014-12-31
WO2007053824A22007-05-10
WO2014076477A22014-05-22
Foreign References:
US3922012A1975-11-25
US20070231072A12007-10-04
JPS6327625A1988-02-05
GB1147434A1969-04-02
GB148767A1921-05-12
Attorney, Agent or Firm:
NEWMAN, Barry (AU)
Download PDF:
Claims:
Claims

1 . A supporting structure for underwater power generators, the supporting structure being of variable buoyancy, the supporting structure being moveable between a first buoyancy state whereby the supporting structure is arranged to float, and a second buoyancy state whereby the supporting structure is arranged to sink.

2. A supporting structure for underwater power generators as claimed in claim 1 , wherein the supporting structure is arranged to sink in a controlled fashion.

3. A supporting structure for underwater power generators as claimed in claim 1 or claim 2, wherein the second buoyancy state is sufficient to sink the supporting structure to a seabed.

4. A supporting structure for underwater power generators as claimed in claim 1 or claim 2, wherein the second buoyancy state is sufficient to sink the supporting structure part way from a sea surface to the seabed.

5. A supporting structure for underwater power generators as claimed in any preceding claim, wherein the underwater power generators are tidal power generators.

6. A supporting structure for underwater power generators as claimed in claim 5, wherein the underwater power generators are tidal turbines.

7. A supporting structure for underwater power generators as claimed in any preceding claim, wherein the supporting structure includes at least one variable buoyancy chamber.

8. A supporting structure for underwater power generators as claimed in claim 7, wherein the first buoyancy state corresponds to the chamber being substantially filled with air, and the second buoyancy state corresponds to the chamber being substantially filled with a ballast material.

9. A supporting structure for underwater power generators as claimed in claim 7 or claim 8, wherein the supporting structure includes two buoyancy chambers.

10. A supporting structure for underwater power generators as claimed in claim 9, wherein the supporting structure is generally elongate, with one buoyancy chamber located at each elongate end.

1 1 . A supporting structure for underwater power generators as claimed in any one of claims 7 to 10, wherein the or each buoyancy chamber includes feet arranged to support the supporting structure on a seabed in the second buoyancy state.

12. A supporting structure for underwater power generators as claimed in any preceding claim, wherein the supporting structure includes anchors.

13. A supporting structure for underwater power generators as claimed in claim 12, wherein the anchors are of variable buoyancy, with a first buoyancy state allowing them to remain fixed to the supporting structure, and a second buoyancy state allowing them to sink to the seabed.

14. A supporting structure for underwater power generators as claimed in claim 12 or 13, wherein the anchors are connected to the supporting structure by cables arranged to maintain in tension.

15. The supporting structure as claimed in claim 10, wherein the supporting structure includes a supporting frame extending between the two buoyancy chambers.

16. A supporting structure for underwater power generators as claimed in claim 15, wherein a plurality of underwater power generators are suspended from the supporting frame.

17. A supporting structure for underwater power generators as claimed in claim 16, wherein each underwater power generator is moveable between a deployed position located beneath the supporting frame and a maintenance position at or above the supporting frame.

18. A supporting structure for underwater power generators as claimed in claim 17, wherein elevation means is provided, arranged to move each underwater power generator between its deployed position and its

maintenance position.

19. A supporting structure for underwater power generators as claimed in claim 18, wherein the elevation means is arranged to rotate relative to the supporting frame, such that the maintenance position may be rotated at 90° to the deployed position.

20. A method for deploying underwater power generators, the method including the steps of locating power generators onto a supporting structure being of variable buoyancy; arranging the supporting structure in a first buoyancy state whereby the supporting structure is arranged to float; moving the supporting structure to a water surface position above a desired location; moving the supporting structure into a second buoyancy state whereby the supporting structure is arranged to sink; and sinking the supporting structure to the desired location.

21 . A method for deploying underwater power generators as claimed in claim 20, wherein the desired location is on the seabed.

22. A method for deploying underwater power generators as claimed in claim 20, wherein the desired location is beneath the water surface but above the seabed.

23. A method for deploying underwater power generators as claimed in any one of claims 20 to 22, wherein the method includes the further step of ballasting the supporting structure to the seabed.

24. A method for deploying underwater power generators as claimed in claim 22, wherein the method includes the further step of including anchors on the supporting structure, and then lowering the anchors to the seabed when the supporting structure is in the desired location above the seabed.

25. A method for deploying underwater power generators as claimed in claim 24, wherein the anchors are of variable buoyancy, and the method includes the step of moving the anchors into a second buoyancy state whereby they are arranged to sink to the seabed.

26. A supporting structure for underwater power generators, the supporting structure having a supporting frame and a plurality of underwater power generators suspended from the supporting frame, each underwater power generator being moveable between a deployed position located beneath the supporting frame and a maintenance position at or above the supporting frame.

27. A supporting structure for underwater power generators as claimed in claim 26, wherein elevation means is provided, arranged to move each underwater power generator between its deployed position and its

maintenance position.

28. A supporting frame for underwater power generators, the supporting frame including at least one supporting foot arranged for contact with a seabed, the supporting foot including a plurality of expandable members, the members being hollow and arranged to be filled with a curable material, such that when filled the expandable members generally conform to the shape of the seabed.

Description:
"METHOD AND APPARATUS FOR DEPLOYING TIDE DRIVEN POWER

GENERATORS"

Field of the Invention

[0001 ] The present invention relates to supporting structures for water- driven power generators. It has been designed primarily for use in the deployment of tide-driven turbines.

Background to the Invention

[0002] The harnessing of tidal power to produce electricity is considered an extremely promising source of renewable energy. Tidal patterns are highly predictable and reasonably consistent, meaning that electricity produced from such a source may be more reliable than some other sources of renewable energy.

[0003] The most common way of producing electricity from tidal power is to locate water-driven turbines near a seabed, aligned in the direction of tidal movement (generally, perpendicular to the shore line).

[0004] There are some significant obstacles to ready adoption of tidal power as an energy source. These include the very high capital cost involved in installing turbines in an underwater location, and the difficulty and expense of maintaining the turbines in their environment.

[0005] The present invention seeks to provide a means of deploying tidal energy turbines which at least partially addresses these concerns.

Summary of the Invention

[0006] According to one aspect of the present invention there is provided a supporting structure for underwater power generators, the supporting structure being of variable buoyancy, the supporting structure being moveable between a first buoyancy state whereby the supporting structure is arranged to float, and a second buoyancy state whereby the supporting structure is arranged to sink. [0007] Preferably, the supporting structure is arranged to sink in a controlled fashion.

[0008] The second buoyancy state may be sufficient to sink the supporting structure to a seabed. Alternatively, it may be sufficient to sink the supporting structure part way from a sea surface to the seabed.

[0009] It is preferred that the underwater power generators are tidal power generators, preferably tidal turbines. In a preferred embodiment, the underwater power generators may be Schottel turbines or similar.

[0010] In a preferred embodiment, the supporting structure includes at least one variable buoyancy chamber. The first buoyancy state may correspond to the chamber being substantially filled with air, and the second buoyancy state may correspond to the chamber being substantially filled with a ballast material such as water.

[001 1 ] The supporting structure may include two buoyancy chambers.

[0012] The supporting structure may be generally elongate, with one buoyancy chamber located at each elongate end.

[0013] Each buoyancy chamber may include feet arranged to support the supporting structure on a seabed in the second buoyancy state.

[0014] The supporting structures may include anchors. The anchors may be of variable buoyancy, with a first buoyancy state allowing them to remain fixed to the supporting structure, and a second buoyancy state allowing them to sink to the seabed.

[0015] The anchors may be connected to the supporting structure by cables. The cables may be arranged to maintain in tension. [0016] The supporting structure may include a supporting frame extending between the two buoyancy chambers. The supporting frame may be formed using a trussed arrangement.

[0017] A plurality of underwater power generators may be suspended from the supporting frame.

[0018] In a preferred embodiment, each underwater power generator is moveable between a deployed position located beneath the supporting frame and a maintenance position at or above the supporting frame.

Elevation means may be provided, arranged to move each underwater power generator between its deployed position and its maintenance position.

[0019] Preferably, the elevation means is arranged to rotate relative to the supporting frame, such that the maintenance position may be rotated at 90° to the deployed position.

[0020] According to a second aspect of the present invention there is provided a method for deploying underwater power generators, the method including the steps of locating power generators onto a supporting structure being of variable buoyancy; arranging the supporting structure in a first buoyancy state whereby the supporting structure is arranged to float; moving the supporting structure to a water surface position above a desired location; moving the supporting structure into a second buoyancy state whereby the supporting structure is arranged to sink; and sinking the supporting structure to the desired location.

[0021 ] The desired location may be on the seabed. Alternatively, the desired location may be beneath the water surface but above the seabed.

[0022] It is preferred that the sinking is done in a controlled fashion.

[0023] The method may include the further step of ballasting the supporting structure to the seabed. [0024] The method may include the further step of including anchors on the supporting structure, and then lowering the anchors to the seabed when the supporting structure is in the desired location above the seabed.

[0025] The anchors may be of variable buoyancy, and the method may include the step of moving the anchors into a second buoyancy state whereby they are arranged to sink to the seabed.

[0026] According to a third aspect of the present invention there is provided a supporting structure for underwater power generators, the supporting structure having a supporting frame and a plurality of underwater power generators suspended from the supporting frame, each underwater power generator being moveable between a deployed position located beneath the supporting frame and a maintenance position at or above the supporting frame. Elevation means may be provided, arranged to move each

underwater power generator between its deployed position and its maintenance position.

[0027] According to a fourth aspect of the present invention there is provided a supporting frame for underwater power generators, the

supporting frame including at least one supporting foot arranged for contact with a seabed, the supporting foot including a plurality of expandable members, the members being hollow and arranged to be filled with a curable material, such that when filled the expandable members generally conform to the shape of the seabed.

Brief Description of the Drawings

[0028] It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings: [0029] Figure 1 is a perspective of a tidal turbine support being an underwater power generator supporting structure in accordance with the present invention;

[0030] Figure 2 is a plan view of the tidal turbine support of Figure 1 ;

[0031 ] Figure 3 is an elevation of the tidal turbine support of Figure 1 , shown in a deployed position;

[0032] Figure 4 is an end view of the tidal turbine support of Figure 1 ;

[0033] Figure 5 is an enlarged portion of the end portion of Figure 4;

[0034] Figure 6 is an alternative foot for use in the tidal turbine support of Figure 1 ;

[0035] Figure 7 is a cross sectional view of the foot of Figure 6 shown during deployment;

[0036] Figure 8 is a cross sectional view of the foot of Figure 9 shown following deployment;

[0037] Figure 9 is an elevation of a tidal turbine support similar to that of Figure 1 , shown during deployment in deep water; and

[0038] Figure 10 is an end view of the tidal turbine support of Figure 9.

Detailed Description of Preferred Embodiments

[0039] Referring to the Figures, there is shown a tidal turbine support 10, The tidal turbine support 10 is generally elongate, having an elongate frame 12 extending between two supporting towers 14.

[0040] The elongate frame 12 is generally rectangular in cross section, and is formed from steel pipes arranged in a truss. In the embodiment shown in the drawings, the elongate frame 12 is 7.5m wide, 10m high and in the order of 80m long.

[0041 ] Each of the supporting towers 14 includes a body portion 18 which is generally vertical, in use, with two foot portions 20 extending from a base of the body portion 18 in a transverse direction.

[0042] Each body portion 18 is generally rectangular prismatic in shape, with a face having a height of about 28m, and a width of 7.5m. The arrangement is such that the elongate frame 12 can be mounted to an upper portion of a face of each body portion 18. Each body portion 18 has a depth of about 5m.

[0043] Each foot portion 20 tapers away from the body portion to an outer width of about 10m. The foot portion has a length (measured away from the body portion 18) of about 12m, and a depth of about 5m.

[0044] Each supporting tower 14 is hollow. The total volume of each supporting tower 14, comprising the volume of the body portion 18 and both of its foot portions 20, is in the order of 2000m 3 .

[0045] The tidal turbine support 10 shown in the drawings has seven tidal turbines 22 spaced along the elongate frame 12 between the two supporting towers 14; and two further turbines 23, each further turbine 23 located on a respective extension portion 24 of the elongate frame 12 positioned on the outside of the supporting towers 14.

[0046] The tidal turbines 22, 23 are mounted to the frame 12 by elevation means in the form of movable rods 26, which are formed from steel pipes. The rods 26 are vertically movable relative to the frame 12, such that the tidal turbines 22 are moveable in a vertical direction between a raised position close to the frame 12; and a deployed position relatively spaced beneath the frame 12. The rods 26 are also arranged to pivot about the frame 12, such that the tidal turbines 22 can be rotated about the frame 12 into a maintenance position where they extend laterally from a top of the frame 12.

[0047] The supporting towers 14 represent buoyancy chambers for the tidal turbine support 10. The supporting towers 14 include means (not shown) to selectively allow the towers 14 to fill with air or to fill with water or other ballast materials.

[0048] When the supporting towers 14 are filled with air, the tidal turbine support 10 is in a first buoyancy state whereby the tidal turbine support overall is less dense than water, and is arranged to float.

[0049] When the supporting towers 14 are filled with water, or other ballasting material such as an alternative fluid or solid material, the weight of the tidal turbine support increases by a significant amount (which in the case of water could be in the order of several hundred tonnes). This moves the tidal turbine support 10 into a second buoyancy state whereby the tidal turbine support overall is more dense than water, and is arranged to sink.

[0050] In order to deploy the tidal turbine support 10, it is maintained in the first buoyancy state. The tidal turbine support 10 can then be towed on the water surface to a location immediately above its desired seabed position.

[0051 ] The supporting towers 14 can then be filled with ballast material, moving the tidal turbine support 10 into the second buoyancy state and allowing it to sink in a controlled fashion onto the seabed 30. This is shown in Figure 3.

[0052] It will be appreciated that in this position the foot portions 20 rest directly against the seabed 30, with the ballast material maintaining the supporting towers 14 in position. It is envisaged that the frame 12 may be positioned such that it is partly beneath the water line 32 at high tide, and generally above the water line 34 at low tide. A slidable gantry platform 40 located atop the frame 12 may extend above water at all times. [0053] The turbines 22 are located with their axes of operation oriented in a transverse direction relative to the elongate direction of the frame 12. In a typical deployment, each turbine has a diameter of 10m, and is located in its deployed position with its centre about 5 - 10m above the seabed 30.

[0054] Electricity generated by the turbines 22 may be fed to the shore by means of an umbilical line 42, passing along the seabed to a 'J-tube' 44 located within one of the supporting towers 14. It is envisaged that an electrical connecting line is located along the frame 12, with electrical connections to each of the turbines 22 being located on the frame in a location designed to stay above the water line 32

[0055] When it is desired to move the tidal turbine support 10 to another location, pumps (not shown) are used to empty the support towers 14 and to return the tidal turbine support 10 to its first buoyancy state, allowing it to float to the surface.

[0056] When maintenance of a turbine 22 is required, the turbine 22 can be raised and rotated via its moveable rod 26. It is anticipated that this action can be achieved from the gantry platform 40. It will be appreciated that this will raise the turbine 22 above the water line 32, allowing maintenance to be conducted in dry conditions.

[0057] An alternative foot 50 (which may also form part of the foot portion 20) is shown in Figures 6 to 8. The alternative foot 50 has an outer casing 52, which is open on a bottom side 54.

[0058] The alternative foot has a plurality of expandable bladders 56 inside. In the embodiment shown, the expandable bladders 56 are elongate, extending from one end of the casing 52 to the other. The embodiment shown has five to seven parallel expandable bladders 56 spaced across the casing 52. [0059] The expandable bladders 56 are fixed to an upper inner surface of the casing 52, opposite the open bottom side 54. This can be seen in Figure 7.

[0060] In use, the foot 50 is lowered to the seabed 30 with the bladders 56 in an unexpanded condition, as shown in Figure 8. The outer perimeter of the bottom side 54 will rest on the seabed 30. When the seabed is rocky or uneven, only a portion of this perimeter will be in contact with the seabed 30.

[0061 ] The expandable bladders 56 are then filled with a curable material, such as a grout or cement. This causes them to expand, and to fill the inside of the casing 52. A free lower surface of each bladder 56 will directly contact the seabed 30. Due to the flowable nature of the uncured grout, the free lower surface will conform to the shape of the seabed.

[0062] As the grout cures, the foot 50 will remain in contact with the seabed 30, with the load of the tidal turbine support 10 being distributed over the full area of the expanded bladders 56. It is anticipated that this will promote stability.

[0063] It will be appreciated that means can be provided to fill the bladders 56 with a grout supplied via grout line from the sea surface. They may be arranged to fill sequentially, or else arranged to fill concurrently.

[0064] Where the tidal turbine support 10 is to be positioned in deeper water, for instance in the order of 40m to 100m, it may not be feasible to have the foot portions 20 located on the seabed 30 while maintaining the frame 12 close to the surface of the water.

[0065] An alternative arrangement is shown in Figures 9 and 10, where the tidal turbine support 10 includes anchors in the form of detachable buoyancy cans 70. The detachable buoyancy cans 70 can be transported in a first buoyancy condition (for instance, air filled) latched to the foot portions 20 of the tidal turbine support 10. [0066] When the tidal turbine support 10 is in a desired position above the seabed 30, the buoyancy cans 70 can be moved to a second buoyancy condition (for instance, filled with water), and the latch released.

[0067] The buoyancy cans 70 can then sink to the seabed 30.

[0068] A tension leg cable 72 extends between each buoyancy can 70 and its associated foot portion 20. The tension leg cable 72 acts to maintain the tidal turbine support 10 in its required position at or near the water surface. The tension leg cables 72 are arranged to stay in tension, even as the buoyancy of the tidal turbine support 10 alters the degree of tension in the leg cables 72 between high and low tide.

[0069] Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.