WO2013013266A1

WO2013013266A1 - Device for harnessing wave energy

Info

Publication number: WO2013013266A1
Application number: PCT/AU2012/000881
Authority: WO
Inventors: John Lawrence DRAKE
Original assignee: Drake John Lawrence
Priority date: 2011-07-26
Filing date: 2012-07-25
Publication date: 2013-01-31
Also published as: EP2764235A1; AU2012286587A1; EP2764235A4

Abstract

Disclosed herein is a device for harnessing wave energy. The device comprises at least one cylinder assembly. The cylinder assembly comprises a tubular member with first and second ends, a reciprocal piston assembly slidingly associated with the tubular member and adapted to move reciprocally between the first and second ends of the tubular member, and a tubular member entry one-way valve at the second end of the tubular member. The reciprocal piston assembly comprises an inner portion located inside the tubular member and comprising a piston one-way valve, and a buoyant outer portion located outside the tubular member. The outer portion is magnetically connected to the inner portion such that reciprocal movement of the outer portion along the outside of the tubular member causes a fluid to be drawn into and driven through the tubular member.

Description

DEVICE FOR HARNESSING WAVE ENERGY

Field of the Invention

The invention relates to devices for harnessing wave energy. Background to the Invention

Renewable or clean energy attracts great interest because, apart from the installations required to generate such energy, obtaining such energy typically has little or no impact on the environment. Clean energy can be produced in a number of different ways, one of which utilizes wave energy.

A number of methods and apparatus which can be used to harness the kinetic energy of waves are known. It would be advantageous to provide alternate methods and apparatus that can be adapted to utilize wave energy over a variety of conditions, for example, conditions relating to wave height, swell direction, tidal movement and storm events.

Summary of the Invention

In a first aspect, the present invention provides a device for harnessing wave energy. The device comprises at least one cylinder assembly. The cylinder assembly comprises a tubular member with first and second ends, a reciprocal piston assembly slidingly associated with the tubular member and adapted to move reciprocally between the first and second ends of the tubular member, and a tubular member entry one-way valve at the second end of the tubular member. The reciprocal piston assembly comprises an inner portion located inside the tubular member and comprising a piston one-way valve, and a buoyant outer portion located outside the tubular member. The outer portion is magnetically connected to the inner portion such that reciprocal movement of the outer portion along the outside of the tubular member causes a fluid to be drawn into and driven through the tubular member. In use, the device of the present invention is installed at an appropriate location to be affected by wave motion (e.g. in an ocean). The tubular member is typically orientated substantially vertically, with the second end of the tubular member being at the lowest point. The device operates when wave motion causes the buoyant outer portion (and hence the magnetically connected inner portion) of the piston located outside the tubular member to rise, causing fluid in the tubular member above the piston to be pumped towards the first end of the tubular member. At the same time, pressure differentials created inside the tubular member cause fluid surrounding the second end of the tubular member to be drawn into the tubular member (below the piston) via the tubular member entry one-way valve. As a wave crest passes the device, the buoyant outer portion of the piston moves (typically under gravity) back towards the second (lower) end of the tubular member. As the piston moves towards the second end- of the tubular member, the fluid pressure in the portion of the tubular member below the piston causes the tubular member entry one-way valve to become sealed and, at the same time, causes the piston one-way valve to open and allow fluid in the portion of the tubular member below the piston to pass through the one way piston valve and into the portion of the tubular member above the piston. As the piston reciprocates between the first and second ends of the tubular member with the wave motion, this process is repeated, resulting in a steady flow of fluid being pumped through the at least one cylinder assembly.,

In some embodiments, the outer portion of the piston assembly is magnetically connected to the inner portion of the piston assembly via one or more magnets provided in the outer and inner portions.

In some embodiments, the inner portion and the outer portion of the piston assembly each comprise a magnetic portion. An inner magnetic portion sealingly engages an inner surface of the tubular member, and an outer magnetic portion which is in close proximity to an outer surface of the tubular member. In some embodiments, the inner magnetic portion may, for example, be a ring around the inner portion of the piston assembly. Similarly, in some embodiments, the outer magnetic portion may, for example, be a ring surrounding the tubular member.

In some embodiments, the inner magnetic portion may be a plurality of spaced apart rings around the inner portion of the piston assembly (i.e. the inner portion magnetic sections are circular in plan cross section). In such embodiments, the outer magnetic portion may be a plurality of rings surrounding the tubular member, the rings being spaced apart along the outer portion of the piston assembly such that they can align with the spaced apart magnets of the inner portion of the piston assembly.

In some embodiments, the polarity of the adjacent magnetic rings may be alternated in order to even more securely retain the inner and outer portions of the piston assembly in alignment. In such embodiments, should these portions start to separate from each other, the repulsion caused by magnetic contact with the adjacent magnetic ring(s) will combine with the attraction of the respective magnetic ring(s) to securely retain the portions of the piston together. As will be appreciated, in some embodiments, a similar outcome may be achieved using a plurality of spaced apart inner and outer magnetic portions which are not ring shaped.

In some embodiments, one or more O-rings may be used to seal any gaps between the inner magnetic portion and the inner surface of the tubular member.

In some embodiments, the piston one-way valve comprises a biasing member and a sealing plate. The biasing member biases the sealing plate towards a position where it closes the one-way valve.

In some embodiments, the tubular member entry one-way valve comprises a biasing means and a sealing plate. The biasing member biases the sealing plate towards a position where it closes the one-way valve. The biasing member may, for example, be a spring attached to the sealing plate. Alternatively, the biasing member may a weight attached to the sealing plate. In alternative embodiments, the biasing member of the tubular member one-way valve may be a spring and the biasing member of the piston one way valve may be a weight, or vice versa.

In some embodiments, the device further comprises an outer cylinder casing which surrounds the cylinder assembly. The outer cylinder casing comprises a plurality of shutters which align substantially parallel with the cylinder; wherein at least a portion of the plurality of shutters is movable between an open configuration in which a wave can pass through the outer cylinder casing and interact with the buoyant outer portion of the piston assembly, and a closed configuration, in which the wave is substantially prevented from passing through the outer cylinder casing.

Closing of the outer cylinder casing can reduce the effect a passing wave can have on the vertical displacement of the buoyant outer portion, and thereby protect the piston assembly etc. when the amplitude of the waves is too great (e.g. in rough ocean conditions).

In some embodiments, a manifold assembly is joined to the first end of the tubular member(s) of the at least one cylinder assembly. The manifold assembly is adapted to receive water pumped from the tubular member by the piston assembly.

In some embodiments, the manifold assembly transfers water flow created through reciprocal movement of the respective piston assembly of the at least one cylinder assembly to an electrical generator for producing electricity.

In some embodiments, the device further comprises a hull assembly, which comprises a pair of spaced apart outer hull sections positioned on either side of the at least one cylinder assembly.

The hull assembly may, in some embodiments, be configured to channel water into a wave chamber formed between the outer hull sections, and provide a portion of the wave chamber between a wave chamber entrance and a wave chamber exit having a reduced width in order to cause an increase in a wave crest as it passes through the wave chamber. In this manner, the amplitude of a wave passing the device can effectively be increased in an area proximal to the tubular member.

In some embodiments, the device further comprises a harness assembly via which the hull assembly is connected to a base. The harness assembly includes a height adjusting assembly which allows for controlled vertical movement of the hull assembly relative to the ocean surface. The harness assembly thus enables the height of the hull assembly to be adjusted relative to the ocean floor in order to allow for tidal movements.

In some embodiments, the height adjusting assembly is a geared roller arrangement which allows for controlled vertical movement of the hull assembly relative to the ocean surface.

In some embodiments, the geared roller arrangement comprises a plurality of geared vertical tracks spaced apart relative to each other around the harness assembly, and a plurality of geared roller assemblies. Each of the geared roller assemblies is associated with a respective geared vertical track and comprises a geared roller which engages with the respective geared vertical track, stabilising rollers for stabilising rotational movement of the geared roller relative to the geared vertical track, and at least one brake (typically a disc brake). Each geared roller comprises a flange on either side of the geared roller which allows for attachment of the gear roller arrangement to the hull assembly.

In some embodiments, the harness assembly further comprises a rotation mechanism which operates around the geared roller arrangement and enables the wave chamber entrance to be orientated so as to face oncoming waves.

The rotation mechanism may, for example, comprise a pair of spaced apart rings with a plurality of ball bearings positioned in between the pair of spaced apart rings. The pair of spaced apart rings comprise a first track which is secured to the base and a second track which is secured to the hull assembly. The device of the present invention may, for example, be adapted to be connected to a base of an ocean wind turbine tower, enabling to device to be anchored relative to an ocean surface.

In a second aspect, the present invention provides a device for harnessing wave energy comprising a hull assembly and a plurality of cylinder assemblies that are divided into first and second groups of cylinder assemblies which are spaced apart relative to each other. The hull assembly comprises a pair of spaced apart outer hull sections and an inner hull section which is positioned in between the outer hull sections, thereby to form a wave chamber having first and second flow paths on either side of the inner hull. The first group of cylinder assemblies is positioned in the first flow path and the second group of cylinder assemblies is positioned in the second flow path. Each of the plurality of cylinder assemblies comprises a tubular member having first and second ends, a reciprocal piston assembly slidingly associated with the tubular member and adapted to move reciprocally between first and second ends of the tubular member, and a tubular member entry one-way valve at the second end of the tubular member. The reciprocal piston assembly comprises an inner portion located inside the tubular member and comprising a piston oneway valve, and a buoyant outer portion. The outer portion is magnetically connected to the inner portion such that reciprocal movement of the outer portion along a length of the tubular member causes a fluid to be drawn into and driven through the tubular member. The hull structure is dimensioned so that a maximum cross-sectional dimension of each flow path reduces at least partly between a wave chamber entrance and a wave chamber exit, thereby causing wave height amplification as a wave passes through the wave chamber thereby increasing a height with which the wave in use is capable of raising the buoyant outer portion.

Each group of cylinder assemblies may, for example, have six cylinder assemblies.

In some embodiments, the device further comprises a manifold assembly which is joined to the first end of each of the plurality of tubular members, thereby allowing water flow created through buoyant movement of the respective piston assemblies to be transferred to an electrical generator assembly for converting the kinetic energy of water flow into electrical energy.

In some embodiments, the assembly is adapted to be connected to a base of an ocean wind turbine tower thereby allowing the hull assembly to be anchored relative to an ocean surface through the wind turbine tower.

Specific embodiments of features of the device of the second aspect of the present invention can be the same as embodiments of the corresponding features of the first aspect of the present invention described herein.

In a third aspect, the present invention provides a device for harnessing wave energy. The device comprises at least one cylinder assembly comprising a tubular member and a piston assembly which is slidingly mounted to the tubular member for reciprocal movement along a length of the tubular member. The piston assembly comprises a buoyant outer portion and a valved inner portion which operates within the cylinder. The piston assembly is configured to use a magnetic effect to transfer movement of the outer portion to the inner portion thereby to provide a means for transferring wave energy to the valved inner portion to drive a fluid through the tubular member.

Also disclosed herein is a device for harnessing wave energy comprising a flotation device which is anchored to a seabed for controlled movement relative to the ocean surface and which includes at least one cylinder assembly having a cylinder, an outer cylinder casing, a piston assembly including an inner portion which is sealingly mounted to the cylinder, and a buoyant outer portion which is magnetically connected to the inner portion through the cylinder so that flotation movement of the outer portion across the ocean surface causes linear movement of the inner portion inside a cylinder of the cylinder assembly. The cylinder has an upper one-way valve assembly and the inner portion includes a lower one-way valve assembly, wherein linear movement of the inner portion inside a cylinder towards the upper one-way valve causes water inside the cylinder to become pressurised and to move through the one-way valve towards an upper end of the cylinder; wherein movement of the inner portion away from the upper one-way valve causes a low pressure area to be formed in between the inner piston and the upper one-way valve thereby causing water to be drawn into the cylinder through the lower one-way valve; and wherein the outer cylinder casing is selectively closeable thereby to regulate the influence of a wave surrounding the cylinder assembly on the outer buoyant portion.

It often is a requirement for wave energy harnessing systems to remain fully functional in all but the most extreme wave conditions. However, oceans are highly variable places and this may often not be possible due to the wide range of wave amplitudes and other variable conditions which may be present in a particular part of the ocean. For example wave data obtained by the inventor for a particular sea area of interest show the average wave height is below 2m for about 69% of the time (252 days per year), between 2 and 4 meters for about 26% of the time (95 days per year), between 4 and 6 meters for about 4% of the time (14 days/year), between 6 to 8 meters 0.59% of the time (2 days/year), and above 8 meters for only 0.14% of the time (about 0.5 day per year). According to the wave data, there are also the occasional freak wave incidents with wave heights up to 14 meters, although these are very rare. Therefore, wave heights can vary from less than 2 meters to around 14 meters. The wave data also indicated that the swell was highly variable in its direction and that the tidal range was also quite significant.

Generally, existing solutions for harnessing wave energy are incapable of adjusting to such a harsh environment having so many variables in order to effectively extract wave energy from waves having wide ranging amplitudes. However, embodiments of the device of the present invention are capable of taking these variables into account, and such embodiments can therefore be utilized in all but the most extreme conditions. Brief Description of the Drawings

In order that the invention can be more readily understood, embodiments of the invention are further described below, by way of example only, with reference to the accompanying drawings.

Figure 1 is a front view showing a schematic representation of a device for harnessing wave energy according to an embodiment of the invention and which is mounted to a base of a wind turbine tower.

Figure 2 is a perspective view showing from a side a schematic representation of the device of Figure 1.

Figure 3 is an end view showing a schematic representation of a wave chamber exit of the hull assembly of the device of Figure 1.

Figure 4 is a cross sectional view showing a schematic representation of the hull structure of the device of Figure 1 having a pair of cylinder assemblies supported by the hull structure.

Figure 5 is a cross sectional view showing a schematic representation of one of cylinder assemblies of Figure 4.

Figure 6 is a cross sectional view showing a schematic representation of a piston assembly used in the cylinder assemblies of Figure 5.

Figure 7 is a plan view showing a schematic representation of the device of Figure 1.

Figure 8 is a cross sectional view showing a tubular member having an outer cylinder casing according to an embodiment of the invention.

Figure 9 is a perspective view showing a schematic representation of an outer cylinder casing according to an embodiment of the invention in which a plurality of slats are in an open configuration. Figure 10 is a perspective view showing a schematic representation of the outer cylinder casing of Figure 9 in which the plurality of slats are in a closed configuration.

Figure 11 is a cross-sectional plan view showing a schematic representation of a harness assembly used in the device of Figure 1 to cause vertical movement and horizontal rotation of the hull structure.

Figure 12 is a cross sectional plan view showing a schematic representation of a geared roller assembly used in a geared roller arrangement and of a rotation mechanism used in the harness assembly of the device of Figure 1.

Figure 13 is a perspective view showing an enlarged schematic representation of the harness assembly of Figure 1.

Figure 14 is a plan view showing a schematic representation of a device in accordance with an alternative embodiment of the invention.

Figure 15 is a schematic representation of a cylinder assembly in the device of Figure 14.

Description of Illustrated Embodiments of the Invention

Although the invention may be used as a discrete unit for harnessing wave energy, for convenience sake it shall be described below mainly as a device for harnessing wave energy which is mounted to a wind turbine tower located in an ocean (such towers are extensively used in locations such as the North Sea).

Referring to the accompanying representations, Figure 1 illustrates a device 10 for harnessing wave energy which is mounted to a base 12 of a wind turbine tower 14 used in a wind farm located in a body of water that typically has waves (e.g. a sea or an ocean). Typically, the base 12 is anchored to a seabed, not shown, of the ocean in which the wind farm operates. The base 12 is designed to provide a stable platform for the wind turbine blades 16 of the wind turbine tower 14. Although the device 10 includes mechanisms which allow for movement (vertically and rotationally) relative to the base 12, such movement is controlled, thereby causing the device 10 to be substantially anchored relative to an oncoming wave crest 18. The device 10 will therefore not float over the top of the wave crest, but will maintain its position whilst the wave crest 18 pushes through the device.

Figures 2 and 3 show the device 10 from various sides in order to illustrate the various components of the device 10. The device 10 includes a turbine assembly 24, which is positioned at a rear 26 of a hull assembly 28 of the device. The hull assembly 28 is mounted to the base 12 and includes a number of cylinder assemblies 30 which are connected via a manifold assembly 32 to the turbine assembly 24. The manifold assembly 32 is configured to transfer seawater pumped from the cylinder assemblies 30 to the turbine assembly 24 for electricity generation. The turbine assembly 24 is, in turn, electrically connected to an electrical substation, not shown, which typically is housed inside the wind turbine tower 14. In a normal installation, the electrical substation is connected to an undersea cabling infrastructure which is designed to channel electricity generated by the wind farm to a distribution network for consumption, for example on land. As best can be seen in Figure 3, the water pumped from the cylinder assemblies 30 is discharged through a chute 34 after having passed through the turbine assembly 24.

Figure 4 shows a vertical cross section through the hull assembly 28, and figure 7 shows a plan view of the hull assembly 28. The hull assembly 28 includes a hull structure 40 which includes a pair of spaced apart outer hull sections 42 with an inner hull section 44 positioned mid-way between the two outer hull sections 42. The outer hull sections 42 and inner hull section 44 define a wave chamber 46 which includes first and second flow paths 48 and 50 which lie between the inner hull section 44 and the outer hull sections 42. The cylinder assemblies 30 are positioned inside the wave chamber 46 such that waves travelling through the first and second flow paths 48 and 50 are capable of influencing the cylinder assemblies 30. Inner hull section 44 has a bulge 51 at its mid-section, which is proximal to the mean water level relative to the device 10. Bulge 51 effectively narrows the first and second flow paths 48 and 50, which causes the relative height of waves travelling through paths 48 and 50 with crests and troughs proximal to the bulge 51 to be amplified. Thus, relatively small waves (e.g. from about 0.25m to about 2m swell range) can be amplified in paths 48 and 50 by the bulge 51. As the waves get bigger, however, their crests and troughs pass through the paths 48 and 50 higher and lower than bulge 51 , therefore the amplitude of such waves is not affected to as great an extent. This configuration can be used to amplify the range of movement in the cylinder assemblies 30 of the device in relatively calm surface conditions (and hence obtain more energy), but without causing any significant increase of wave amplitude under conditions where this is not necessary or might damage the device 10. Water pumped through the cylinder assemblies 30 is transferred to the turbine assembly 24 (not shown in Figure 4) via manifold assembly 32.

One of the cylinder assemblies 30 is shown in greater detail in Figure 5. The cylinder assembly 30 includes a tubular member or cylinder 54 and a piston assembly 56 which is slidingly associated with the cylinder 54 for reciprocal movement in between upper 58 and lower 60 ends thereof (the piston assembly 56 is shown in a lighter colour at upper 58 and lower 60 ends). A cylinder entry one-way valve 62 is mounted to the lower end of the cylinder 54.

The piston assembly 56 includes a buoyant outer portion 64 and an inner portion 66 which carries a piston one-way valve 68. The manifold assembly 32 is connected to the cylinder 54 at the upper end 58. The piston assembly 56 is configured to use magnetic attraction to transfer movement of the outer portion 64 along a length 70 of the cylinder 54 to the inner portion 66, thereby providing a means for transferring wave energy to the inner valved portion to drive fluid or seawater through the cylinder. The buoyant movement of the outer portion 64 along the length 70 of the cylinder 54 causes seawater to be drawn into and to be driven through the cylinder 54 using pressure differentials created inside the cylinder 54 through operation of the cylinder entry one-way valve 62 and the piston one-way valve 68, as will be described below. The construction of the inner portion 66, including the one-way valve 68 is shown in greater detail in Figure 6. The inner portion 66 sealingly engages an inner surface 76 of the cylinder 54. The inner portion 66 includes magnetic sections 78 and the outer portion 64 includes magnetic sections 80, which magnetically connects the inner 66 and outer 64 portions to each other. The magnetic sections 78 and 80 each include five strong magnets which, in one example, are in the form of permanent magnets such as a neodymium magnet. The magnets may also be created by using electrical current. More or less (or larger or smaller) magnets may be required, depending mainly on the size of cylinder 54 (and hence the volume of water to be displaced).

The magnetic sections 78 sealingly engage the inner surface 76. A number of O-rings 82 are also provided between the magnetic sections 78 in order to provide a double seal between the inner portion 66 and inner surface 76. The positioning of the O-rings 82 and magnetic sections 78 cause the sealing alignment of the inner portion inside the cylinder so that the inner portion is concentrically aligned with the cylinder such that the seal between the inner portion 66 and inner surface 76 remains throughout the reciprocal movement between the upper and lower ends 58 and 60 of the cylinder.

The piston one-way valve 68 is sealingly mounted inside inner portion 66. The cylinder entry one-way valve 62 and the piston one-way valve 68 substantially have the same constructions. For this reason, only the piston one-way valve 68 will be described in detail below.

The piston one-way valve 68 includes a framework 84, a biasing member in the form of a weight 85 (in alternative embodiments, e.g. where cylinder 54 was not in a substantially vertical orientation, a compression spring could similarly be used) which is anchored to the framework. The framework includes an entry flange 86. A sealing plate 88 that can move inside the framework 84 between an open position and a closed position (Figure 8 shows the closed position) is also provided. The weight 85, which may be a lead weight due to its high density and corrosion properties, is configured to bias the sealing plate 88 into sealing engagement with the entry flange 86, which substantially closes the valve 68 and prevents water from moving through inner portion 66. However, movement of the sealing plate 88 away from the entry flange 86 allows water to flow through the inner portion 66 because the valve is open.

Referring to Figures 5 and 6, the piston one-way valve 68 and the cylinder entry one-way valve 62 are aligned relative to each other so that the lead weight 85 bias the sealing plate 88 (and the corresponding sealing plate of the cylinder entry valve, not shown) towards a lower entrance 94 of the cylinder 54. With this configuration of the valves 62 and 68, movement of the inner portion 66 towards the entrance 94 pushes a lower column of water 96 inside the cylinder 54 towards the entrance 94, thereby effectively pressurising the lower column of water 96. However, the weight 85 in the inner portion 66 will release the sealing plate 88 once this pressure is above a predetermined pressure. Once the lower column of water 96 is pressurised up to the predetermined pressure, the sealing plate 88 moves away from the entry flange 86, which allows water from the lower column of water 96 to flow between the entry flange 86 and sealing plate 88 and through inner portion 66 (as shown by the arrows), and hence into an upper column of water 100. Since the sealing plate of the valve 62 is biased towards the entrance 94, pressurisation of the lower column of water 96 will effectively increase the seal between the sealing plate (not shown) and the entry flange (not shown) of the cylinder entry one-way valve 62.

The materials used in the construction of the buoyant outer portion 64 cause the outer portion 64 to have a weight whereby, in the absence of other forces, the outer portion 64 moves towards the entrance 94 because of gravity. However, the outer portion 64 also has a float chamber (not shown) which causes the outer portion 64 to float on the ocean surface. Thus, the outer portion 64 rises as the wave crest 18 passes the cylinder 54. This movement of the outer portion 64 is transferred via the magnetic sections 78 and 80 the inner portion 66. As the wave crest 18 passes, gravitational movement of the buoyant outer portion 64 from a wave crest 18 to a wave trough 104 (see Figure 1) causes the inner portion 66 to move towards the entrance 94, thereby pressurising the lower column of water 96, with the effect discussed above. Upward buoyant movement of the outer portion 64 from the wave trough 104 to the wave crest 18 causes the inner portion 66 to move away from the entrance 94, which effectively reduces the pressure of the lower column of water 96 and causes the upper column of water 100 to be pressurised. This reduction in pressure in the lower column of water 96 counteracts the biasing force of the weight (not shown) in the cylinder entry one-way valve 62 to break the seal of this valve. As a result, seawater is drawn into the cylinder 54 through the entrance 94. At the same time, water in the upper column 100 is forced into the manifold assembly 32 and channelled towards the turbine assembly 24.

This upward and downward movement is transferred from the outer portion 64 to the inner portion 66 by way of the magnetic attraction discussed above. Therefore, no direct connection is required between the inner and outer portions 66 and 64. This enables the full-length 70 of the cylinder 54 to be used for reciprocal movement of the buoyant outer portion 64 to generate water pressure inside the cylinder.

The correct positioning of the lower end 60 of cylinders 54 are facilitated by the buoyancy of the hull structure 40 which causes the device 10 to float on the ocean with the lower ends 60 submerged when the hull structure is in a wave trough 104. However, the anchoring of the hull assembly 28 onto the base 12 substantially prevents sudden movement of the hull structure 40, for example by riding buoyantly across the wave crest 18.

The manifold assembly 32 is connected to respective upper ends 58 of the cylinders 54. A ball valve (not shown) may be mounted adjacent each upper end 58, and be independently operable when necessary to effectively shut off cylinder assembly 30 when the ball valve is closed. Closure of the ball valve may be required, for example, in situations such as during rough sea conditions in order to reduce the risk of the piston assembly 56 being moved along the cylinder 54 with such force to damage or, in a worst-case scenario, even break the cylinder assembly 30.

The ball valve (not shown) can be operated in tandem with an outer cylinder casing 114 which is shown in detail in Figures 8 to 12. The outer cylinder casing 114 surrounds the cylinder 54 and includes a plurality of shutters 116 which are substantially parallelly aligned with the cylinder 54. The shutters 116 are movable between an open configuration 118, shown in Figure 9, where waves can pass through the outer cylinder casing 114, and a closed configuration 120, shown in Figure 10, where waves are substantially blocked from passing through the outer cylinder casing 114. Operation of the outer cylinder casing 114 reduces the effect which a passing wave can have on the vertical displacement of the buoyant outer portion 64, again to protect the piston assembly 56 in rough conditions.

As can be seen in Figure 7, the outer cylinder casing 114 may also provide an external float chamber 124 in which the buoyant outer portion 64 of the piston assembly 56 operates. The shutters 116 of the outer cylinder casing 114 assist in preventing vertical displacement of the buoyant outer portion 64 from the effect of the elements.

Figures 11 to 13 illustrate examples of mechanism by which the device 10 can be secured to the base 12 of the wind turbine tower 14. The device includes a harness assembly 128 via which the hull assembly 28 is connected to the base 12 (via outer hull sections 42 and inner hull section 44). Depending on the size and weight of the device 10, more than one harness assembly may be required in order to securely secure the device 10 to the base 12. For example, in the illustrated embodiment (see Figure 13), there are three harness assemblies attached to upper, middle and lower sections of the device 10. The harness assembly 28 includes a number of geared roller arrangements 130 (there are 8 in Figure 1 ), which allow for controlled vertical movement of the device 10 relative to the ocean surface to allow for tidal movements.

Referring in particular to Figure 12, each geared roller arrangement 130 has a plurality of geared vertical tracks 132 which are spaced apart relative to each other around the harness assembly 128, and a plurality of geared roller assemblies 134, each of which is associated with a respective geared vertical track. Each geared roller assembly 134 has a geared roller 136 which is engaged with the geared vertical track 132. The geared roller arrangement 130 also has stabilising rollers 138, which stabilise rotational movement of the geared roller 136 relative to the geared vertical track 132, and at least one disc brake 140. Each geared roller 130 includes a flange 142 on either side of the geared roller, which allows the gear roller arrangement 130 to be attached to hull assembly 28.

As can be seen in Figures 11 to 13, the harness assembly 128 also includes a rotation mechanism 146 which operates around the geared roller arrangement 130 thereby allowing the entrance of wave chamber 46 to be rotated such that it faces oncoming waves. The rotation mechanism 146 has a pair of spaced apart rings 148 and 150 with a plurality of ball bearings 152 positioned in between the spaced apart rings. The ring 148 forms a first track which is secured to the base 12 of the wind turbine tower 14 and the ring 150 forms a second track which is secured to the hull structure 40. The rotation mechanism 146 also has brakes 154 (there are four in Figure 11), which are operable to prevent unwanted rotation of the device 10 with respect to the base 12 (e.g. in response to a wave coming from a slightly different direction to the swell, or when a vessel comes alongside the device for servicing or the like).

The harness assembly 128 allows the hull assembly 28 to rotate to face oncoming swells and rise or fall with the tides. Thus, wave chamber entrance 46 can be optimally positioned facing towards the oncoming waves at a constant height for the wave crests 18 to travel down the first and second flow paths 48 and 50 and maximise the effect a wave crest can have on the operation of the cylinder assembly 30. The ability to make these adjustments advantageously enables the maximum amount of power to be generated under almost any given operating conditions.

The geared roller assembly 30 is designed to allow for slow vertical movement of the hull assembly 28 upwards and downwards with the tide, over a long period of time. In the illustrated example, the harness assembly 28 includes a set of eight vertical geared tracks 132, each of which extend substantially vertically relative to the base 12. The geared rollers 136 run up and down a respective geared track 132. The geared roller assembly 130 is, in turn, connected to the rotation mechanism 146, which allows the geared rollers to rotate 360° about the base 12. In order to prevent sudden movement upwards and downwards of the geared rollers along a respective geared track, included into the geared roller assembly are disk brakes 140. Brakes 140 will slowly pulse on and off thereby allowing the hull assembly 28 to be slowly moved in a vertical direction relative to the base 12 to compensate for tidal changes. The brakes 140 substantially prevent the hull assembly 28 from making relatively fast upward and downward movements relative to the base 12 with each passing wave.

As discussed above, the wave chamber 46 is designed to amplify the wave height of the wave crest 18 when the wave height is within a certain range. By allowing the device 10 to substantially always face oncoming swells, the correct alignment of the wave chamber entrance 108 allows the wave crest to travel between the inner 44 and outer 42 hull sections. The wave crest is effectively "squeezed" when passing through the hull because of the substantially reduced cross-sectional diameter of first and second flow paths 48 and 50. The positioning of the cylinder assembly 30 inside the first and second flow paths also creates an obstacle which reduces the cross-sectional area of the first and second flow paths. These factors combine to amplify the wave crest when it is around the cylinder assemblies.

An alternate, simpler, embodiment of the device is shown in Figures 14 and 15. Device 200 for harvesting wave energy is shown tethered to a post 202 in the water. Device 200 is free to rotate about post 202 so that it always faces towards the direction of the swell. Device 200 has a basic catamaran hull shape, with six cylinder assemblies 204 being housed between outer hulls 206. Hulls 206 contain buoyancy chambers 208 that enable the device 10 to float at an appropriate height with respect to the mean water level.

The basic structure of the cylinder assemblies 204 is shown in Figure 15. Each cylinder assembly 204 has a cylinder 210 and an outer float portion 212, which has a buoyancy that enables it to float on the surface of the water and rise as a wave crest moves through the device 200, but a weight sufficient to enable the portion 212 to fall under gravity towards to bottom of cylinder 210 in order to cause the pumping action described above.

Described herein is a particular embodiment of a device for harnessing wave energy. It is envisaged that other embodiments of the invention could exhibit any number and combination of the features described above. It is to be understood that variations and modifications to the embodiments described above can be made without departing from the spirit and scope of this invention.

Claims

CLAIMS:

1. A device for harnessing wave energy, the device comprising at least one cylinder assembly, the cylinder assembly comprising:

a tubular member with first and second ends,

a reciprocal piston assembly slidingly associated with the tubular member and adapted to move reciprocally between the first and second ends of the tubular member, and a tubular member entry one-way valve at the second end of the tubular member;

wherein the reciprocal piston assembly comprises:

an inner portion located inside the tubular member and comprising a piston one-way valve, and

a buoyant outer portion located outside the tubular member; wherein the outer portion is magnetically connected to the inner portion such that reciprocal movement of the outer portion along the outside of the tubular member causes a fluid to be drawn into and driven through the tubular member.

2. The device of claim 1, wherein the outer portion of the piston assembly is magnetically connected to the inner portion of the piston assembly via one or more magnets provided in the outer and inner portions.

3. The device of claim 1 or claim 2, wherein the inner portion and the outer portion of the piston assembly each comprise a magnetic portion; wherein an inner magnetic portion sealingly engages an inner surface of the tubular member and an outer magnetic portion is in close proximity to an outer surface of the tubular member.

4. The device of claim 3, wherein the inner magnetic portion is a ring around the inner portion of the piston assembly.

5. The device of claim 3 or claim 4, wherein the outer magnetic portion is a ring surrounding the tubular member.

6. . The device of claim 3, wherein the inner magnetic portion is a plurality of spaced apart rings around the inner portion of the piston assembly.

7. The device of claim 6, wherein the outer magnetic portion is a plurality of rings surrounding the tubular member, the rings being spaced apart along the outer portion of the piston assembly such that they can align with the spaced apart magnets of the inner portion of the piston assembly.

8. The device of claim 6 or claim 7, wherein the polarity of the adjacent magnetic rings is alternated.

9. The device of any one of claims 1 to 8, wherein the piston one-way valve comprises a biasing member and a sealing plate, wherein the biasing member biases the sealing plate towards a position where it closes the oneway valve.

10. The device of any one of claims 1 to 9, wherein the tubular member entry one-way valve comprises a biasing means and a sealing plate, wherein the biasing member biases the sealing plate towards a position where it closes the one-way valve.

11. The device of claim 9 or 10, wherein the biasing member is a spring attached to the sealing plate.

12. The device of claim 9 or 10, wherein the biasing member is a weight attached to the sealing plate.

13. The device of any one of claims 1 to 12, wherein the device further comprises an outer cylinder casing which surrounds the cylinder assembly, wherein the outer cylinder casing comprises:

a plurality of shutters which align substantially parallel with the cylinder; wherein at least a portion of the plurality of shutters is movable between an open configuration in which a wave can pass through the outer cylinder casing and interact with the buoyant outer portion of the piston assembly, and a closed configuration, in which the wave is substantially prevented from passing through the outer cylinder casing.

14. The device of any one of claims 1 to 13, wherein a manifold assembly is joined to the first end of the tubular member of the at least one cylinder assembly, the manifold assembly being adapted to receive water pumped from the tubular member by the piston assembly.

15. The device of claim 14, wherein the manifold assembly is joined to the first ends of the tubular members of a plurality of the cylinder assemblies.

16. The device of claim 14 or claim 15, wherein the manifold assembly transfers water flow created through reciprocal movement of the respective piston assembly of the at least one cylinder assembly to an electrical generator for producing electricity.

17. The device of any one of claims 1 to 16, wherein the device further comprises a hull assembly, the hull assembly comprising a pair of spaced apart outer hull sections positioned on either side of the at least one cylinder assembly.

18. The device of claim 17, wherein the hull assembly is configured to channel water into a wave chamber formed between the outer hull sections, wherein a width of the wave chamber is reduced at a portion between a wave chamber entrance and a wave chamber exit, thereby causing an increase in a wave crest as it passes through the wave chamber.

19. The device of claim 17 or claim 18, wherein the device further comprises a harness assembly via which the hull assembly is connected to a base; wherein the harness assembly includes a height adjusting assembly which allows for controlled vertical movement of the hull assembly relative to the ocean surface.

20. The device of claim 19, wherein the height adjusting assembly is a geared roller arrangement which allows for controlled vertical movement of the hull assembly relative to the ocean surface.

21.The device of claim 20, wherein the geared roller arrangement comprises: a plurality of geared vertical tracks spaced apart relative to each other around the harness assembly, and a plurality of geared roller assemblies, each of which is associated with a respective geared vertical track and comprises:

a geared roller which engages with the respective geared vertical track,

stabilising rollers for stabilising rotational movement of the geared roller relative to the geared vertical track, and

at least one brake;

wherein each geared roller comprises a flange on either side of the geared roller which allows for attachment of the gear roller arrangement to the hull assembly.

22. The device of any one of claims 19 to 21 , wherein the harness assembly further comprises a rotation mechanism which operates around the geared roller arrangement and enables the wave chamber entrance to be orientated so as to face oncoming waves.

23. The device of claim 22, wherein the rotation mechanism comprises a pair of spaced apart rings with a plurality of ball bearings positioned in between the pair of spaced apart rings; wherein the pair of spaced apart rings comprises a first track which is secured to the base and a second track which is secured to the hull assembly.

24. The device of any one of claims 1 to 23, which is adapted to be connected to a base of an ocean wind turbine tower, enabling to device to be anchored relative to an ocean surface.

25. A device for harnessing wave energy comprising:

a hull assembly; and

a plurality of cylinder assemblies that are divided into first and second groups of cylinder assemblies which are spaced apart relative to each other; the hull assembly comprising: a pair of spaced apart outer hull sections and an inner hull section which is positioned in between the outer hull sections, thereby to form a wave chamber having first and second flow paths on either side of the inner hull;

wherein the first group of cylinder assemblies is positioned in the first flow path and the second group of cylinder assemblies is positioned in the second flow path;

each of the plurality of cylinder assemblies comprising:

a tubular member having first and second ends,

a reciprocal piston assembly slidingly associated with the tubular member and adapted to move reciprocally between first and second ends of the tubular member, and

a tubular member entry one-way valve at the second end of the tubular member;

wherein the reciprocal piston assembly comprises an inner portion located inside the tubular member and comprising a piston one-way valve, and a buoyant outer portion; wherein the outer portion is magnetically connected to the inner portion such that reciprocal movement of the outer portion along a length of the tubular member causes a fluid to be drawn into and driven through the tubular member; and wherein the hull structure is dimensioned so that a maximum cross- sectional dimension of each flow path reduces at least partly between a wave chamber entrance and a wave chamber exit, thereby causing wave height amplification as a wave passes through the wave chamber thereby increasing a height with which the wave in use is capable of raising the buoyant outer portion.

26. The device of claim 25, wherein each group of cylinder assemblies has six cylinder assemblies.

27. The device of claim 25 or claim 26 further comprising a manifold assembly which is joined to the first end of each of the plurality of tubular members, thereby allowing water flow created through buoyant movement of the respective piston assemblies to be transferred to an electrical generator assembly for converting the kinetic energy of water flow into electrical energy.

28. The device of any one of claims 25 to 27, wherein the assembly is adapted to be connected to a base of an ocean wind turbine tower.

29. A device for harnessing wave energy, the device comprising at least one cylinder assembly comprising a tubular member and a piston assembly which is slidingly mounted to the tubular member for reciprocal movement along a length of the tubular member; the piston assembly comprising a buoyant outer portion and a valved inner portion which operates within the cylinder; wherein the piston assembly is configured to use a magnetic effect to transfer movement of the outer portion to the inner portion thereby to provide a means for transferring wave energy to the valved inner portion to drive a fluid through the tubular member.