AU2018241205B1

AU2018241205B1 - Terminator Wave Energy Converter

Info

Publication number: AU2018241205B1
Application number: AU2018241205A
Authority: AU
Inventors: Callum Samuel Mainstone
Original assignee: Plithos Renewables Pty Ltd
Current assignee: Plithos Renewables Pty Ltd
Priority date: 2018-10-08
Filing date: 2018-10-08
Publication date: 2019-09-19
Anticipated expiration: 2038-10-08

Abstract

TERMINATOR WAVE ENERGY CONVERTER The ability to harness the power of ocean waves for renewable energy generation has long been sought. Barriers to achieving this include engineering a cost-effective structure strong enough to survive harsh ocean conditions with materials suitable for such a corrosive environment. This patent describes a novel terminator wave energy converter that addresses these issues to move the industry closer to commercial acceptance.

Description

TERMINATOR WAVE ENERGY CONVERTER

DESCRIPTION [001] The ability to harness the power of ocean waves for renewable energy generation has long been sought. Barriers to achieving this include engineering a cost-effective structure strong enough to survive harsh ocean conditions with materials suitable for such a corrosive environment. This patent describes a novel terminator wave energy converter that addresses these issues to move the industry closer to commercial acceptance.

[002] Current wave energy converters are point absorbers made from buoys, submerged heaving floats that move back and forth with a pivot mounted on the seabed and oscillating water columns that direct air through a bidirectional turbine. Attenuator converters use the relative motion of multiple connected floats aligned perpendicular to the wavefront while terminator converters have floating structures aligned parallel the wavefront.

[003] As the energy contained in ocean waves is dependent on the wave height, which all converter types access and width of wave front intercepted, a terminator device will generate the most power for any given mass and physical size of converter.

[004] Drawing 1 depicts an exploded view of the novel terminator wave energy converter. Two parallel floats are comprised of circular arrays of hollow, semi-circle ended square bricks (1) that are layered in a staggered formation. The alignment of the bricks is maintained by mid-float flanges (2) and end flanges (3) and all components are held together with threaded rods (4) and nuts (5) that extend throughout the floats. The floats are connected with levers (6) by a driveshaft (7) that passes through the end flanges (3) to connect to the power-take-off system. A large diameter internal (8) pipe is positioned within each float to provide more buoyancy and allow equipment to be secured in a waterproof enclosure.

[005] In operation, one terminator float of the novel wave energy converter is moored (9) shoreside in a fixed or relatively fixed position with anchoring to the seabed. This is the float that contains power-take-off equipment. A second oceanside terminator float (10) is positioned to intercept the oncoming waves and is free to follow the vertical path of the wave. It is this relative motion that creates an oscillating rotation in the driveshaft (7) that can be exploited to extract useful energy with power-take-off mechanisms not detailed in this patent.

[006] An isometric view of the assembled wave energy converter is shown in Drawing 2. The exact dimensions can be incrementally changed with the brick (1) construction element allowing the sizes of the floats to be increased in both circumference and width. A larger circumference will increase unit buoyancy per meter of terminator width and greater widths, achieved by having more layers, increase the wavefront that can be intercepted. As wave energy intensity varies greatly with location, a wider terminator can compensate for a weaker environment while using a standardized size of power-take-off system.

2018241205 08 Oct 2018 [007] Drawing 3 presents an orthographic view of an individual brick (1). To satisfy the function of modularity in circumference, the semicircular ends of the brick must have a diameter equal to the straight edge of the brick and half the size of the total length of the brick. The height of the brick can be varied, provided a uniform height is used across each layer.

[008] The manufacturing process determines the number of components required to assemble each brick (1) module. The exploded view of a brick (1) in Drawing 4 has the top and bottom faces as identical end plates (11) that can be injection moulded or milled from sheet material while the shell (12) and rod supports (13) are extruded profiles or moulded pieces.

[009] Manufacturing the bricks (1) from plastics such as PVC and ABS with UV stabilizing agents can offer lightweight, electrically insulating and corrosion resistant bricks. Joining the parts together with welding or adhesives will provide watertight seals suitable for being submerged in seawater. The mass of bricks (1) positioned at the bottom of the floats can be increased by filling with high density material prior to sealing. This will reduce the impact of rotational forces on the float and improve stability. Colour can be added to the bricks with the use of pigmented plastics to increase visibility for recreational or commercial activity around installed wave energy converters.

[010] The mid-float flange (2), as presented in Drawing 5, is placed at increments along the terminator to maintain the float’s rigidity and has an inner diameter to support the internal pipe (8). The flange shape used in Drawing 5 is a circle with 16 rod holes (14) to align 8 bricks although other shapes with different wave attenuation properties such as an inverted teardrop can be used. The mid-float flange (2) can extend beyond the area covered by the bricks to provide mounting points (15) for mooring shackles.

[011] The end flange (3) of the structure is the same shape as the mid-float flange (2) with the rod hole (15) alignment consistent as shown in Drawing 6. As with the mid-float flange (2), mooring shackle mounting points (15) can be present as part of the end flange (3). An alternative is to have these outer mounting points as separate pieces that are bolted onto the outside surface with the float’s threaded rods (4) and nuts (5).

[012] The inside face of the end flange (3) is designed to seal the internal pipe (8) while the outer face has a torque tube (16) to support the driveshaft (7). The torque tube (16) of the moored float’s end flange is open on both sides to allow the driveshaft (7) access into the internal pipe (8) where it connects to an appropriate power-take-off system. Marine grade bearings and watertight shaft seals housed within the torque tube reduce driveshaft (7) friction and prevents water from entering the internal pipe (8).

[013] The length of the rods (4) determine the maximum width of the terminator floats. The threaded rods (4) and nuts (5) along with all metal components of the terminator floats are made from grade 316 stainless steel due to its strength and resistance to seawater corrosion.

2018241205 08 Oct 2018 [014] The levers (6) of the terminator wave energy converter are comprised of rigid beams with crank linkages (17) and are located on either end of the floats. It is this component that connects the floats together and transforms the heaving motion of the free-moving float (10) into an oscillating rotational motion of the driveshaft (7) of the moored float (11). Drawing 7 has one assembled section of this mechanical connection with a lever (6), driveshaft (7) and crank linkage (17). The components in the drawing are fixed together with nuts (5) and bolts (18) although other methods such as welding are possible. The length of the levers (6) can be made to match site conditions to optimise the terminator for different wave periods dominant in certain locations.

[015] For the terminator to extract energy from ocean waves there must be relative motion between two objects connected by a mechanical linkage. While this can be achieved with two floating structures, the moored float can be replaced by a ship, offshore platform or shore mounted foundation for the power-take-off system. These alternatives may offer increased access to the power-take-off system for maintenance at the expense of the ability to change the orientation of the converter to face the predominant wave direction.

[016] As a mechanism to extract energy from ocean waves, the terminator wave energy converter covered in this patent can be scaled in width to access more ocean wavefront using modular buoyant bricks supported by flanges to construct a floating structure.

EDITORIAL NOTE

Claims

1. A wave energy converter is comprised of two floating tubular structures connected in tandem that are each assembled from staggered arrays of buoyant bricks with threaded rods inserted through each layer of brick.

2. A wave energy converter wherein the buoyant bricks of Claim 1 have the profile of a square capped with semicircles on two opposite ends, where the semicircle diameter is equal to the length of the square.

3. A wave energy converter wherein the buoyant bricks of Claim 1 have holes extending throughout the profile located at the centre of the semicircle radius from Claim 2 to facilitate the insertion of the threaded rods.

4. A wave energy converter wherein the buoyant bricks of Claim 1 can be constructed to be hollow or filled with another substance to control the weight of each brick.

5. A wave energy converter wherein the width of the tubular structure of Claim 1 is dependent on the number of layers of buoyant bricks and the height of each layer of buoyant brick used in the structure.

6. A wave energy converter wherein the circumference and shape of the tubular structures of Claim 1 is determined by the shape and threaded rod hole positions of end flanges located on the outside face of the first and last layer of buoyant bricks and mid-float flanges that are positioned between layers of buoyant bricks within the floating tubular structures.

7. A wave energy converter wherein the buoyant bricks of Claim 1 are constrained to the end flanges of Claim 6 to form the floating tubular structures in Claim 1 by having the threaded rods that extend throughout the floating tubular structures attached to the end flanges with nuts.

8. A wave energy converter wherein one tubular floating structure of Claim 1 has mooring mounting points located on the end flanges or mid-float flanges of Claim 6.

9. A wave energy converter wherein the floating tubular structures of Claim 1 are aligned such that the length of the threaded rods is parallel to the wavefront.