Apparatus for generating energy from a wave

Abstract

A wave powered apparatus for generating rotational mechanical energy, having a buoyant energy generation capsule and upper and lower inclined guide surfaces to restrain and guide movement of the energy generation capsule. The apparatus is partly submerged in a body of water and the energy generation capsule rolls in a unidirectional manner about a capsule axis of rotation along the guide surfaces, rolling up the incline in response to forces from waves in the body of water and rolling down the incline in response to gravitational force.

Description

[0001] APPARATUS FOR GENERATING ENERGY FROM A WAVE

[0002] FIELD OF THE INVENTION

[0003] This invention relates to an apparatus for generating unidirectional rotational kinetic energy from waves such as from those in a lake, sea, or ocean swell. The invention also relates to a device for generating electricity and further to a desalination device.

[0004] BACKGROUND

[0005] There is an ever increasing need to develop reliable, efficient, accessible and usable methods of renewable energy generation. The motion of the waves an in ocean or lake contain immense amounts of kinetic energy and therefore hold significant potential for energy generation. Numerous examples exist of designs of systems attempting to harness this wave energy and convert it to a usable form. However, most such designs are not implemented or do not succeed commercially due to their complexity, unreliability, inefficiency, and / or the economics and specialist knowledge required for installing, repairing, maintaining and operating such systems. For example, some systems may be inoperable or have only minimal levels of operability in low wave environments. Some installation sites can be dangerous and difficult to access, with the associated risks and challenges being exacerbated by devices that are unwieldly size and difficult to manoeuvre.

[0006] It is an object of at least preferred embodiments of the present invention to address one or more of the above-mentioned disadvantages and / or to at least provide the public with a useful alternative.

[0007] In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally to provide a context for discussing features of the invention. Unless specifically stated otherwise, reference to such external documents or sources of information is not to be construed as an admission that such documents or such sources of information, in any jurisdiction, are prior art or form part of the common general knowledge in the art.

[0008] SUMMARY OF THE INVENTION

[0009] In a first aspect, the present invention provides a wave powered apparatus for generating rotational mechanical energy. The apparatus comprises a buoyant energy generation capsule and upper and lower inclined guide surfaces arranged to restrain and guide movement of the energy generation capsule. The apparatus is configured to be partly submerged in a body of water. The energy generation capsule is configured to roll in a unidirectional manner about a capsule axis of rotation, along the guide surfaces as it rises in response to forces from waves in the body of water and lowers in response to gravitational forces.

[0010] The upper and lower guide surfaces may be spaced apart and face each other. The upper and lower guide surfaces may be substantially parallel. The upper and lower guide surfaces may be vertically aligned.

[0011] The apparatus may comprise two pairs of upper and lower guide surfaces, with the generation capsule having two coaxial drive axles, each drive axle arranged to roll along one of the pairs of upper and lower guide surfaces thereby causing rotation of the generation capsule about the capsule axis of rotation.

[0012] Optionally each drive axle comprises an engagement portion for engaging the respective upper and lower guide surfaces in turn, the engagement portion comprising a grip enhancing feature for reducing slip between the drive axle and the respective guide surfaces. The grip enhancing feature may comprise an elastomeric surface or another material or coating to provide an improved coefficient of friction. In one embodiment the grip enhancing feature comprises reconstituted rubber with a urethane binder.

[0013] In an embodiment, the upper and lower guide surfaces comprise a grip enhancing surface. The grip enhancing surface may comprise a knurled or otherwise indented surface. In one embodiment, the grip enhancing surface is provided by a surface treatment comprising crushed glass and epoxy.

[0014] In an embodiment, an incline angle of the upper and lower inclined guide surfaces is adjustable.

[0015] In an embodiment, motion of the energy generation capsule is guided by the upper guide surface(s) as the capsule rises and by the lower guide surface(s) as it lowers.

[0016] The apparatus may be anchored or feathered to the seabed or ground or to a natural feature may be on a moveable structure or vehicle able to be moved and positioned and orientated from the shore.

[0017] The apparatus may be partly submerged in a body of water at a height such that a majority of the upper and lower guide surfaces are positioned above a wave trough height, and a majority of the upper and lower guide surfaces are positioned below a wave crest height. In an embodiment, the height of the guide surfaces is adjustable. Alternatively, the height of the guide surfaces may be fixed.

[0018] In an embodiment, the volume and weight of the energy generation capsule is selected such that it weighs between about 10% and about 80% of the weight of an equivalent displaced volume of water from the body of water. For example, the volume and weight of the energy generation capsule is selected such that it weighs between about 40% and about 60% of the weight of an equivalent displaced volume of water from the body of water. In an embodiment, the volume and weight of the energy generation capsule is selected such that it weighs about 50% of the weight of an equivalent displaced volume of water from the body of water.

[0019] The apparatus may comprise a ballast. The ballast may contain water or may comprise a solid material of a suitable mass.

[0020] In a second aspect, the present invention provides a wave powered apparatus for generating electrical energy, comprising the apparatus according to the first aspect, wherein the energy generation capsule comprises a generator having a drive shaft, and a housing. The generator is rotatable about the capsule axis of rotation relative to the housing, and relative rotation of the generator drives rotation of the drive shaft to generate electrical energy.

[0021] In an embodiment, a pinion is operatively coupled to the drive shaft and a complementary annular gear provided internally in the housing and arranged to rotate with the housing, wherein rotation of the housing causes rotation of the pinion. The pinion may be coupled to the drive shaft via a clutch. The clutch may be a sprag clutch or any other suitable clutch.

[0022] In an embodiment, the generator is arranged to hang from a support, the support is arranged to rotate about the capsule axis of rotation and relative to the housing, such that a major part of the generator remains in a lower portion of the energy generation capsule as the capsule rotates.

[0023] In an embodiment, the generator is an alternator.

[0024] In an embodiment, the drive shaft is parallel and offset from the capsule axis of rotation.

[0025] In an embodiment, the drive shaft is coupled to a flywheel. A cable may be provided for transferring electricity generated by the generator out of the energy generation capsule. In an embodiment, the cable exits the housing along the capsule axis of rotation. A slip ring may be provided at the point the cable exits the housing.

[0026] In a third aspect, the present invention provides a desalination apparatus, comprising the energy generation apparatus according to the first aspect, wherein the energy generation capsule comprises a housing, a pump arranged within housing, and a reverse osmosis filter fluidly connected to the pump. The filter has an inlet to receive salt water, and an outlet for the provision of desalinated water. The pump and filter are rotatable relative to the housing about the capsule axis of rotation and relative rotation between the housing and the pump and filter drives the pump drives to draw or drive salt water through the filter.

[0027] In an embodiment, the housing comprises or defines a reservoir for saltwater, and the pump is fluidly coupled to the reservoir. The housing may comprise a plurality of inlets to allow the ingress of saltwater into the reservoir.

[0028] The apparatus comprises an internal casing within the housing, containing the pump and the filter and fixed relative to the pump and filter, and wherein the housing is rotatable relative to the internal casing. The internal casing may be watertight. The internal casing may typically be air-filled but alternatively may contain a vacuum or other gasses.

[0029] In an embodiment, the pump comprises an inlet arranged to draw salt water through an aperture in the casing.

[0030] In an embodiment, at least a major part of the pump and filter are suspended below the axis of rotation under gravitational forces.

[0031] In an embodiment, the pump comprises a drive shaft and a drive coupling is provided to operatively couple to the housing to the pump drive shaft; wherein rotation of the housing thereby causes rotation of the drive shaft. The drive coupling may be coupled to the drive shaft via a clutch.

[0032] A central support may be provided along the rotation axis and fixed for rotation with the housing, wherein the drive coupling couples the pump to the central support.

[0033] In an embodiment, the filter outlet is fluidly coupled to a hose that exits the apparatus along the rotation axis, to convey desalinated water out of the apparatus. The filter may comprise one or more secondary outlets for conveying waste brine from the apparatus.

[0034] The housing may comprise a plurality of curved waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus, sized and arranged such that fluid exiting the tangential outlets induces a torque on the generation capsule in the rotation direction.

[0035] In an embodiment, the housing comprises a plurality of tangential waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus. The tangential outlets may be orientated I extend in the opposite direction to a unidirectional rotation direction of the generation capsule, such that fluid exiting the tangential outlets induces a torque on the generation capsule.

[0036] In an embodiment, the apparatus may include a plurality of filters. The filters may be arranged in series or parallel.

[0037] In a fourth aspect, the present invention provides an apparatus for generating electrical energy, comprising a housing configured to rotate about an axis of rotation; and an electrical generator arranged the housing. The housing is rotatable relative to the electrical generator and wherein the housing and the electrical generator are coupled via a drive coupling such that rotation of the housing relative to the electrical generator drives the electrical generator to thereby generate electrical energy.

[0038] In an embodiment, the electrical generator is arranged to allow for orbital movement of the generator about the axis of rotation.

[0039] In an embodiment, the electrical generator is arranged to hang below the axis of rotation under gravitational forces. For example, the electrical generator is arranged to hang below the axis of rotation under gravitational forces throughout full rotations of the housing. In an embodiment, the generator is arranged to hang from a support and the support is arranged rotate about the axis of rotation and relative to the housing.

[0040] The electrical generator may comprise a drive shaft and the drive coupling may comprise a pinion operatively coupled to the drive shaft, with a complementary annular gear provided internally in the housing and arranged to rotate with the housing; wherein rotation of the housing thereby causes rotation of the pinion. In an embodiment, the pinion is coupled to the drive shaft via a clutch, for example, a sprag clutch or freewheel clutch or overrunning clutch, or any other suitable clutch.

[0041] In an embodiment, the drive shaft is parallel and offset from the axis of rotation.

[0042] In an embodiment, the electrical generator is an alternator.

[0043] The apparatus may further comprise a flywheel to smooth power generation.

[0044] A cable may be provided for transferring electricity generated by the generator out of the housing. The cable may exit the housing along the generation capsule's axis of rotation.

[0045] The housing may be watertight. The housing may typically be air-filled but alternatively may contain a vacuum or other gasses.

[0046] In an embodiment, the housing includes two coaxial drive axles along the axis of rotation, and the drive axles are configured to roll along guide surfaces to induce rotation of the housing.

[0047] In an embodiment, each drive axle comprises an engagement portion having a grip enhancing feature for engaging and reducing slip between the drive axles and the guide surfaces. The grip enhancing feature may comprise an elastomeric or similar surface.

[0048] In an embodiment, the apparatus is for use in a body of water and the housing is sealed to prevent the ingress of water.

[0049] In an embodiment, the volume and weight of the apparatus is selected such that it weighs between about 10% and about 80% of the weight of an equivalent displaced volume of water from the body of water. For example, the volume and weight of the apparatus is selected such that it weighs between about 40% and about 60% of the weight of an equivalent displaced volume of water from the body of water. In an embodiment, the volume and weight of the apparatus is selected such that it weighs about 50% of the weight of an equivalent displaced volume of water from the body of water.

[0050] The apparatus may comprise a ballast (which may be either saltwater or a suitably dense solid material). In a fifth aspect, the present invention provides a water treatment apparatus, comprising a housing configured to rotate about an axis of rotation, a pump arranged within the housing, and a filter fluidly connected to the pump, and having an inlet to receive water, and an outlet for the provision of filtered water. The housing is rotatable relative to the pump and the filter and the housing and the pump are coupled via a drive coupling such that rotation of the housing relative to the pump drives the pump to draw or drive water through the filter.

[0051] The water treatment apparatus may have any one or more of the features described above in relation to the third aspect.

[0052] In a sixth aspect, the present invention provides a desalination apparatus, comprising a housing configured to rotate about an axis of rotation, a pump arranged within the housing, and a reverse osmosis filter fluidly connected to the pump, and having an inlet to receive salt water, and an outlet for the provision of desalinated water. The housing is rotatable relative to the pump and the filter and the housing and the pump are coupled via a drive coupling such that rotation of the housing relative to the pump drives the pump to draw or drive salt water through the filter.

[0053] In an embodiment, the housing comprises or defines a reservoir for saltwater, and the pump is fluidly coupled to the reservoir. The housing may comprise a plurality of inlets to allow the ingress of saltwater into the reservoir. The inlets may include filters or grills to prevent the ingress of aquatic wildlife or debris into the reservoir.

[0054] In an embodiment, the apparatus comprises an internal casing within the housing, the internal casing containing the pump and the filter and being fixed relative to the pump and filter, with the housing being rotatable relative to the internal casing.

[0055] In an embodiment, the internal casing is sealed to prevent the ingress of water into the casing.

[0056] The pump may comprise an inlet arranged to draw salt water through an aperture in the casing.

[0057] In an embodiment, pump and filter are arranged to allow for orbital movement of the pump and filter about the axis of rotation relative to the housing. In an embodiment, the pump is arranged to hang below the axis of rotation under gravitational forces.

[0058] In an embodiment, the filter is arranged to hang below the axis of rotation under gravitational forces.

[0059] In an embodiment, the pump is arranged to hang below the axis of rotation under gravitational forces throughout full rotations of the housing.

[0060] In an embodiment, the filter is arranged to hang below the axis of rotation under gravitational forces throughout full rotations of the housing.

[0061] In an embodiment, the pump comprises a drive shaft and the drive coupling comprises a belt drive or other gear assembly operatively coupled to the housing and to the pump drive shaft; wherein rotation of the housing thereby causes rotation of the drive shaft.

[0062] In an embodiment, the drive coupling is coupled to the drive shaft via a clutch such as a sprag clutch or freewheel clutch or overrunning clutch, or any other suitable clutch.

[0063] In an embodiment, the drive shaft is parallel and offset from the axis of rotation.

[0064] A central support may be provided along the rotation axis and fixed for rotation with the housing, wherein the drive coupling is attached to the central support.

[0065] In an embodiment, the filter outlet is fluidly coupled to a hose that exits the apparatus along the rotation axis, to convey desalinated water out of the apparatus.

[0066] In an embodiment, the filter comprises one or more secondary outlets for conveying waste brine from the apparatus.

[0067] The housing may comprise a plurality of curved waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus, arranged such that fluid exiting the tangential outlets induces a torque on the generation capsule in the rotation direction. The housing may include a plurality of tangential waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus.

[0068] In an embodiment, the tangential outlets extend in the opposite direction to a rotation direction of the apparatus, such that fluid exiting the tangential outlets induces a torque on the apparatus in the rotation direction.

[0069] The housing may include two coaxial drive axles along the axis of rotation, and the drive axles are configured to roll along guide surfaces to induce rotation of the housing.

[0070] Each drive axle comprises an engagement portion having a grip enhancing feature for engaging and reducing slip between the drive axles and the guide surfaces. The grip enhancing feature may comprise an elastomeric surface or another material providing an increased coefficient of friction.

[0071] In an embodiment, the volume and weight of the apparatus is selected such that it weighs between about 10% and about 80% of the weight of an equivalent volume of water from the body of water. For example, the volume and weight of the apparatus is selected such that it weighs between about 40% and about 60% of the weight of an equivalent volume of water from the body of water. In an embodiment, the volume and weight of the apparatus is selected such that it weighs about 50% of the weight of an equivalent volume of water from the body of water.

[0072] The apparatus may comprise a ballast. For example, a ballast for filling with variable quantities of water, or a ballast made of solid, suitably dense, material.

[0073] In a seventh aspect, the present invention provides a water pumping apparatus, comprising: an external housing configured to rotate about an axis of rotation; a pump arranged within the external housing; nd wherein the external housing is rotatable relative to the pump; and wherein the external housing and the pump are operatively coupled via a drive coupling such that rotation of the external housing relative to the pump drives the pump to draw or drive water out of the apparatus to shore for storage and use.

[0074] The water pumping apparatus may have any one or more of the features described above in relation to the third aspect. This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually described.

[0075] The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims that include the term 'comprising', other features besides those prefaced by this term can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in a similar manner.

[0076] The term 'wave' as used in this specification and claims includes waves and swells generated on lakes, rivers, seas and the ocean.

[0077] It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range and any range of rational numbers within that range (for example, 1 to 6, 1.5 to 5.5 and 3.1 to 10).

[0078] Therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed.

[0079] As used herein the term '(s)' following a noun means the plural and / or singular form of that noun. As used herein the term 'and / or' means 'and' or 'or', or where the context allows, both.

[0080] BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The present invention will now be described by way of example only and with reference to the accompanying drawings in which:

[0082] Figure 1 is a perspective view of an example apparatus for generating rotational energy from the waves of a swell;

[0083] Figure 2 is a side schematic view, illustrating operation of the apparatus of Figure 1, with the energy generation capsule positioned between the peak and trough of a wave;

[0084] Figure 3 is partial perspective view showing the position of the energy generation capsule of the apparatus of Figure 1 positioned at a wave peak;

[0085] Figure 4 is partial perspective view showing the position of the energy generation capsule of the apparatus of Figure 1 positioned at a wave trough;

[0086] Figure 5 is a perspective view of one embodiment energy generation capsule for generating electrical energy; Figure 6 is a cut-away view of the energy generation capsule of Figure 5; and

[0087] Figure 7 is a perspective view of an example embodiment apparatus for desalination;

[0088] Figure 8 is a cut-away perspective view of the apparatus of Figure 7; and

[0089] Figure 9 is a further cut-away perspective view of the embodiment of Figures 7 and 8;

[0090] Figure 10 is a is a cut-away perspective view of an alternative embodiment apparatus for desalination; and

[0091] Figure 11 is a perspective view of an alternative embodiment apparatus for generating rotational energy from the waves of a swell.

[0092] DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0093] While the present invention may be embodied in many different forms for the purpose of promoting an understanding of the principles of the present invention, reference will now be made to Figures 1 to 6 which show an exemplary embodiment apparatus 1 for generating rotational energy from the horizontal (surge) and / or vertical (heave) force components of a wave, and the associated buoyancy / displacement force, for example, in a lake, sea, or ocean.

[0094] Referring to Figure 1, the apparatus 1 comprises a buoyant energy generation capsule 3 and upper and lower inclined guide surfaces 5, 7. The apparatus 1 is configured to be partly submerged in a body of water when it is in use. A part of the device or a majority of the device may protrude above the body of water in use.

[0095] The upper and lower inclined guide surfaces 5, 7 are substantially parallel surfaces, spaced apart from each other vertically. The upper and lower inclined guide surfaces 5, 7 may be opposing, facing surfaces. The upper guide surface 5 may be positioned directly above the lower guide surface or it may be offset horizontally.

[0096] Some embodiments may include more than one upper guide surface 5 and more than one lower guide surface 7. In the embodiment shown, the apparatus 1 comprises two laterally spaced and parallel upper guide surfaces 5 and two laterally spaced and parallel lower guide surfaces 7. These guide surfaces 5, 7, are arranged as a left pair and a right pair of opposing upper and lower inclined guide surfaces.

[0097] Each upper and lower guide surface pair 5, 7 defines a movement track 6 therebetween for receipt of a portion of the energy generation capsule 3. The movement track 6 is in the shape of an elongated slot having a slot width w that is wider than a diameter of the received portion of the energy generation capsule 3, such that the received portion only contacts one of the upper or lower guide surfaces 5, 7, at a given time. In the embodiment shown, the upper and lower guide surfaces 5, 7 are in the form of guide rails provided by a frame 4. The frame includes a supporting structure and end stops Ila, 11b linking each upper guide surface 5 with the respective lower guide surface 7 and defining the ends of the movement tracks 6. Optionally the frame may comprise other members to provide stiffness, in particular, to maintain the spacing between the upper and lower guide surfaces 5, 7. In alternative embodiments, the frame 4 may have other forms. For example, each movement track 6 may be provided by inclined slots in a plate, with the slot sides forming the upper and lower guide surfaces.

[0098] The guide surfaces 5, 7 are inclined from horizontal. The incline, length and height of the guide surfaces 5, 7 is selected such that the lower ends Ila are positioned below the lowest anticipated wave troughs such that they remain submerged during use, and the upper ends 11b are positioned above the highest anticipated wave peak during use.

[0099] For applications where the apparatus is installed in a tidal location, the wave peaks may be highest at high tide and the wave troughs may be lowest during low tide. The apparatus may optionally be installed and configured to rise and fall with the tide such that, relative to the seabed, it is positioned higher at high tide and lower at low tide.

[0100] In some embodiments the upper and lower guide surfaces 5, 7 may include a vertical or near vertical portions at the upper and / or lower ends of the guide surfaces to allow additional upwards movement at the upper end of the movement track 6 and / or additional downwards movement at the lower end of the movement track 6. This may reduce the risk of the transfer of excessive forces to the frame in scenarios where the wave peaks exceed the anticipated heights or where the wave troughs are lower than anticipated. The upper ends 11b and / or lower ends Ila of the guide surfaces 5, 7 may be linked (as shown) to form and end stop, or open in embodiments having sufficient redundant length beyond the anticipated maximum and minimum movement heights.

[0101] In the embodiment shown, the guide surfaces 5, 7 are oriented at a 1:4 incline. However, the incline may vary between embodiments and be selected depending on the characteristics of the installation site, the inertial characteristics of the energy generation capsule, the expected wave profile (including amplitude and frequency) and / or the requirements for the generation output. For example, the guide surfaces may be inclined at an angle a between about 3 degrees and about 70 degrees, preferably between about 5 degrees and about 45 degrees, for example between about 10 degrees and about 30 degrees. In the example embodiments shown herein, the inclination angle a is about 14 degrees above horizontal, but in alternative embodiments the inclination angle may be smaller or larger.

[0102] In some embodiments, the angle a of inclination may be adjustable. For example, by adjusting an angle of the frame 4, or by tilting the frame 4 or apparatus 1 as a whole. The angle a may be adjustable at the time of installation and / or during use of the apparatus 1 to tune performance of the apparatus to the current wave conditions at the installation site.

[0103] In some embodiments, the angle a of inclination may be configured to vary between upward and downward strokes of the apparatus. For example, in one embodiment the guide rails may be hinged or pivotable about an axis proximal a lower end of the guide rails, such that they are movable between a maximum inclination angle and a minimum inclination angle. The guide rails may be biased towards the maximum inclination angle. The incline of the guide rails is steeper during the upward movement of the energy generation capsule 3, and flatter during the downward movement of the energy generation capsule, with the mass of the capsule under gravity acting to lower the incline. Such a configuration may be helpful to improve synchronisation between the apparatus and the prevalent wave profile, particularly for environments where the waves are not sinusoidal in profile. This may provide an element of automatic environmental tuning and optimisation to the then prevalent conditions.

[0104] Adjustment of the incline angle between upward and downward motions could alternatively be configured to deliberately cause asynchronisation between the apparatus and the wave. For example, if it is determined in response to the ambient environmental conditions that it will be optimal for the apparatus to be "out-of-phase" with the prevalent waves. Asynchronous movement may be desirable in embodiments where the incline angle of the guide surfaces is small and wave motion causes the capsule to experience a high level of inundation and submersion by the waves.

[0105] The inclined guide surfaces 5, 7 may follow a linear or contoured incline path. The guide surfaces 5, 7 may comprise a linear, horizontal or angled, or contoured, for example, curved, transverse cross-sectional profile. The transverse cross-sectional profile of the two guide surfaces may be opposite and symmetrical. Curved or symmetric angled profiles may help facilitate consistent engagement, prevent 'racking' or twisting of the generation capsule 3 about a vertical axis, and / or tailor the speed of rotation of the energy generation capsule along the movement tracks 6. Referring now to Figures 5 and 6, the drive axles 9 may comprise locating features such as a lip or flange 12, or other contour to locate the engagement portion of the drive axles accurately on the respective guide surface and / or to prevent excessive transverse movement of the drive axles 9 and to maintain the generation capsule 3 in an orthogonal orientation relative to the guide rails and minimise or prevent 'racking' or twisting about a vertical axis. The embodiment 201 shown in Figure 11 illustrates one alternative form flange tor engaging the guide rails. Additionally or alternatively stabilisers may be provided that run longitudinally along a length of the guide rails to provide additional rigidity.

[0106] "Racking" or twisting of the generation capsule about a vertical axis may also be minimised or prevented by coating the lip or flange 12 or other stabilisers in contact with the guide rails, and or, the corresponding contacting lateral faces of the guide rails or frame 4 with a low friction material or coating, for example an ultra-high molecular weight polyethylene (UHMWPE). The coating of UHMWPE is to ensure that the generation capsule does not catch and jam on the guide rails.

[0107] The upper and lower guide surfaces 5, 7 each comprise a grip-enhancing feature to increase the coefficient of friction between the energy generation capsule and the surface. For example, the guide surfaces 5, 7 may each comprise a textured surface such as a knurled, grooved or otherwise indented surface. Alternatively, the upper and lower guide surfaces 5, 7 may be coated with a friction enhancing coating or cover, or comprise a material selected to provide increased frictional forces between the guide surface and the energy generation capsule 5, 7.

[0108] In the embodiment shown, the energy generation capsule 3 comprises two coaxial drive axles 9. The drive axles 9 extend along and define a capsule axis of rotation RA.

[0109] The drive axles 9 may be fixed to the body of the energy generation capsule 3, which is a housing 10, such that the body and drive axles 9 move and rotate synchronously as a whole. The drive axles 9 may be integrally formed with the body of the energy generation capsule 3 or may be fixedly attached to the housing 10.

[0110] In alternative embodiments, the drive axels 9 may be rotatably mounted relative to the to the body of the energy generation capsule 3 and coupled to the body of the energy generation capsule, for example via a drive coupling such as a belt drive and variable transmission system, such that rotation of the drive axles at a first rotational velocity causes rotation of the body at a second, different, rotational velocity. Each drive axle 9 comprises an engagement portion that is received by a respective guide track 6 and is arranged to engage and roll along the respective upper and lower guide surfaces 5, 7 in turn. This thereby causes the generation capsule 3 to rotate about the capsule's axis of rotation RA.

[0111] The drive axle engagement portions may comprise a grip enhancing feature to reduce slip between the drive axle 9 and the respective guide surface 5, 7. For example the engagement portion may be encased in an elastomeric material such as a heavy-duty rubber coating or cover. Alternatively the engagement portion may be comprise a coating or cover consisting of an alternative material that increases the coefficient of friction between the drive axle 9 and the respective guide surface 5, 7. Alternatively, the drive axles 9 may each comprise a textured surface such as a knurled, grooved, or otherwise indented surface or an alternative treatment or coating or cover. This grip-enhancing feature is intended to interface with the friction enhanced upper and lower guide surfaces 5, 7, to prevent the drive axles from sliding along the guide surfaces instead the axels will grip the relevant surface forcing the generation capsule to rotate on its axis to move along the movement track 6.

[0112] In some alternative embodiments, the upper and lower guide surfaces 5, 7 may comprise engagement features such as a racked surface, ribs, or a series of recesses configured to engage complementary engagement features or a complementary axle profile on the drive axles 9, thereby avoiding slip between the components.

[0113] In other embodiments, there may be one or more pairs of laterally parallel secondary guide rails under and / or over the generation capsule, on either side of a circumferential "fin" protruding from the generation capsule. These secondary guide rail pairs may be helpful to provide extra guidance to the capsule as it moves linearly, which may be helpful depending on the prevalent environmental conditions.

[0114] Some embodiments may include a feature on the exterior of the capsule to maximise the utilisation of the wave to encourage a rotation, for example, embedded contours or vanes.

[0115] In the embodiment shown, the width w of the guide tracks 6 is larger than the diameter of the axels 9, such that the drive axles 9 only contact the lower guide surfaces 7 or the upper guide surfaces 5 at any one time. The width w of the guide track 6 is selected to be only slightly larger than the diameter of the axels 9. Preferably the width w is selected to be between about 101% and about 110% of the diameter of the axles 9. The energy generation capsule 3 is a buoyant body, that is, it is lighter than the equivalent volume of water it displaces and so is, when partially or completely submerged, subject to a buoyant force that causes it to rise to the surface of a body of water. The volume and weight of the energy generation capsule 3 is selected such that the energy generation capsule 3 weighs between about 10% and about 80% of the weight of an equivalent displaced volume of water. For embodiments for use in saltwater, the energy generation capsule 3 may weigh between about 10% and about 80% of the weight of an equivalent displaced volume of saltwater. For embodiments for use in freshwater, the energy generation capsule 3 may weigh between about 10% and about 80% of the weight of an equivalent displaced volume of freshwater. In some embodiments, the volume and weight of the energy generation capsule 3 is selected to weigh between about 40% and about 60% of the weight of an equivalent displaced volume of freshwater or saltwater. In the present example, the energy generation capsule 3 weighs about 50% of the weight of an equivalent displaced volume of freshwater or saltwater.

[0116] The ratio of the longitudinal length of the energy generation capsule to its diameter or transverse dimension may vary between embodiments. Some embodiments of the generation capsules will have a higher length to diameter ratio, and some will have a lower length to diameter ratio. The shape and aspect of the energy generation capsule may be selected depending on the expected site and environmental conditions. Other embodiments may not be circular in cross-sectional profile.

[0117] The housing 10 of the energy generation capsule 3 may comprise a polymeric material, for example high density polyethylene, or any other suitable material such as an aluminium alloy or composite material. A ballast (not shown) may be provided within the housing 10 to enable to weight of the capsule 3 to be increased to the required value. The ballast may comprise a space, tanks, or chamber within the capsule 3 that can be filled, at least partially, with water. This advantageously would allow additional weight to be added to the energy generation capsule at the installation site, avoiding the need to transport the additional weight overland or from shore to the site, and to be varied by the users in order to optimise the apparatus in response to the then current environmental conditions. The ballast may have sufficient capacity that they can be selectively filled to sink the energy generation capsule, for example temporarily for storm survival.

[0118] The apparatus 1 is intended to be is anchored to the seabed, ground, or structure to partly submerge the apparatus 1 in a body of water. The apparatus may be directly fixed to the ground, for example via a tether, or anchored via existing infrastructure such as an oil rig, ocean wind turbine, a jetty, wharf, or breakwater, for example by tethering or fixing the apparatus to the infrastructure, or anchored to a sub-surface free-swinging moored structure. Alternatively, the apparatus may be on a moveable structure or vehicle able to be moved and positioned and orientated from the shore. The apparatus 1 is configured to be oriented with the guide tracks 6 substantially parallel to the direction S of the swell, with the lower ends Ila of the guide surfaces positioned in the water and oriented towards direction of the oncoming swell.

[0119] The apparatus 1 may be fixed to the ground or positioned on a movable structure or vehicle able to be moved and positioned and orientated from the shore in locations having a consistent swell / wave direction, for example for on-shore and near shore locations. For locations where the swell direction S is variable, the orientation of the apparatus may be adjustable. For example, the orientation of the apparatus 1 may be selectively adjustable or the apparatus may be configured to self-orient into the swell direction. In some embodiments, the apparatus may be anchored to the seabed by way of a tether to allow rotation of the apparatus about an anchor point, and the apparatus may include a rudder, fin, or other feature configured to align parallel to the flow direction to thereby allow the device to self-orientate.

[0120] In some embodiment, the structure may be able to rise and fall relative to the seabed, for example, in response to the tide. This may be by way of the structure's height relative to the seabed being adjustable, or by way of the structure having a neutral buoyancy.

[0121] The apparatus is installed with the upper ends 11b of the guide surfaces 5, 7 positioned above the water. Preferably the upper ends 11b remain above the water throughout each wave cycle, that is, they are positioned higher than the maximum expected wave peak. Preferably the lower ends Ila remain submerged in the water throughout each wave cycle, that is, they are positioned lower than the lowest expected wave trough.

[0122] The height and / or incline of the apparatus 1 may be fixed, for example, for locations where the swell is steady and consistent. Alternatively, the height and / or incline of the guide surfaces 5, 7 may be adjustable. For example, the apparatus may be anchored to the seabed by way of one or more adjustable tether(s) that is adjustable in length.

[0123] In some embodiments, the apparatus 1 may be selectively lowered under the surface of the body of water temporarily in storm conditions, to minimise the risk of damage to the apparatus. For example, by shortening an adjustable tether. Alternatively, the apparatus 1 may comprise one or more actuators selectively operable to raise the apparatus 1 above the water temporarily in storm conditions, to minimise the risk of damage to the apparatus. Preferably a majority of the upper and lower guide surfaces are positioned both above a wave trough height and below a wave crest height. The length of the guide surfaces 5, 7 positioned both above a wave trough height and below a wave crest height is the effective length of the guide surfaces, along which the energy generation capsule will roll and generate rotational kinetic energy.

[0124] Operation of the apparatus 1 will now be described with particular reference to Figures 2 to 4.

[0125] In a neutral position of the apparatus 1, the energy generation capsule 3 is positioned at the surface of the water, with part of the capsule 3 above the level of the water, and part of the capsule 3 below the water. The proportion of the capsule positioned above and below the water in this rest position is, at least in part determined by the buoyancy of the capsule 3.

[0126] As an incoming wave approaches, it inundates the energy generation capsule 3 and the capsule 3 becomes at least momentarily partially or fully submerged under the surface of the wave. The underwater capsule 3 is then subject to buoyant forces acting vertically upwards on the capsule. This buoyant force pushes the capsule drive axles 9 into contact with the upper guide surfaces 5. The upper guide surfaces 5 constrain the upward motion of the capsule, preventing it from floating directly upwards and instead guiding the capsule 3 forwards, in the direction S of the wave movement, and gradually upwards.

[0127] Frictional forces between the drive axles 9 and the upper guide surfaces 5 prevent the drive axles 9 from sliding along the guide surfaces and instead produce a resultant torque on the energy generation capsule 3, causing the energy generation capsule 3 to spin in a direction of rotation r about the capsule rotation axis RA.

[0128] As the water level at the energy generation capsule 3 continues to increase during the wave cycle as the wave moves over the apparatus, from the trough of the wave to the peak, the energy generation capsule 3 rises together with the water level. The capsule 3 rolls about its rotation axis RA along the upper guide surfaces 5 as it is pushed forward and upwards towards the upper end 11b of the apparatus. This occurs even once the generation capsule is no longer fully submerged.

[0129] The length of time or the proportion of each wave cycle that the energy generation capsule 3 remains submerged will depend on the buoyancy of the capsule, its rotational inertia, the diameter of the drive shafts 9, the incline of the guide surfaces, and characteristics of the utilisation of the kinetic energy within the capsule, and the characteristics of the passing wave. Where the rotational energy is used to generate electricity (as described further below), the speed of the capsule movement may be influenced and / or manipulated by the current being drawn, and where the kinetic energy is used to desalinate water (as described further below), the speed of the capsule movement may be influenced and / or manipulated by the volumetric output of the pump.

[0130] In an embodiment, there may be a flow smoothing / control device, to ensure a generally smooth flow of water and to manipulate the speed of the rotation of the generation capsule to either ensure it is in-phase, or depending on the ambient environmental conditions, out- of-phase, with the prevalent waves. Such a flow smoothing device may comprise an accumulator and may include a valve to selectively alter an aperture size to change the flow rate of fluid out of the accumulator.

[0131] Manipulation of the speed of the capsule movement by altering the current drawn or the output of the pump or use of a flow smoothing device can be useful to either ensure the generation capsule is either in-phase with the prevailing waves or deliberately out-of-phase. Out-of-phase movement may have application to allow an incoming wave have time to more fully inundate the generation capsule to increase the buoyancy force available to it during the upward stroke.

[0132] The drive axles 9 move towards the upper ends 11b of the guide surfaces, but preferably don't reach the upper ends before the wave peak passes. If the drive axles 9 do reach the upper ends 11b, for example in a very large wave, the ends 11b act as a stop to prevent further movement of the generation capsule.

[0133] As the wave peak moves past the energy generation capsule, the capsule 3 is at least momentarily positioned fully above the surface of the water. At this point the gravitational force acting on the capsule 3 cause the capsule to drop, bringing the drive axles 9 into contact with the lower guide surfaces 7.

[0134] The lower guide surfaces 7 constrain the downward motion of the capsule 7, preventing it from dropping further directly downwards and instead guiding the capsule back against the direction of the swell S.

[0135] Frictional forces between the drive axles 9 and the lower guide surfaces 7 prevent the drive axles 9 from sliding along the guide surfaces 7 and instead produce a resultant torque on the energy generation capsule 3, causing the capsule 3 to spin in a direction of rotation r about the capsule rotation axis RA. The spin direction r is the same direction of rotation as for the upwards movement of the capsule 3 such that the direction of rotation of the capsule is unidirectional throughout the cycle. This may advantageously reduce energy loss that may result from a system in which the rotation of the energy generation capsule 3 changes between the upward stroke and the downwards stroke, providing a more efficient arrangement. Preferably the distance w between the two interfacing guide surfaces is small, such that the transition between the upward and downward strokes is almost instantaneous.

[0136] As the water level at the energy generation capsule 3 continues to drop as the wave peak moves away from the apparatus, the energy generation capsule 3 lowers together with the water level, rolling about its rotation axis along the lower guide surfaces 7 as it is rolls down the guide surfaces 7 under gravity towards the lower end Ila of the apparatus. This occurs even once the generation capsule is no longer fully above the water.

[0137] The length of time or the proportion of each cycle that the energy generation capsule 3 is fully out of the water will depend on the buoyancy of the capsule 3, its inertia, and the characteristics of the passing wave, as described above in relation to the length of time the energy generation capsule 3 if fully or partially submerged.

[0138] The drive axles 9 move towards the lower ends Ila of the guide surfaces, but preferably don't reach the lower ends before the trough of the wave passes. If the drive axles 9 do reach the lower ends Ila, the ends Ila act as a stop to prevent further movement of the energy generation capsule 3. In other embodiments, the inclined guide surfaces will at the lowest extremity have an increased incline, near the vertical, so that any unexpectedly low trough will not place undue stress on the overall system and therefore acting as a pressure safety valve.

[0139] This process repeats cyclically with each passing wave.

[0140] For a given wave amplitude, a lower guide surface incline angle a necessitates longer guide surfaces 5, 7, which in turn mean that the energy generation capsule must complete a greater number of revolutions to move along the guide surfaces with each passing wave, which is generally advantageous for the generation of rotational kinetic energy.

[0141] Figure 11 shows an alternative embodiment apparatus 201. In this embodiment, unless otherwise described, like reference numbers are used to describe like features compared to the embodiment of Figure 1 to 6, but with the addition of 200. Electrical power generation

[0142] In some embodiments of the apparatus 1, the rotational kinetic energy of the energy generation capsule 3 may be utilised to generate electricity. Figure 6 illustrates one exemplary embodiment in which the energy generation capsule comprises an apparatus 3 for generating electrical energy.

[0143] The housing 10 of the apparatus 3 houses at least one generator 21 having a drive shaft 27. In the embodiment shown, the capsule 3 includes two generators 21 positioned adjacent opposite ends of the housing 10.

[0144] The generators 21 may comprise any suitable generator or alternator. In the example embodiment, the generators are permanent magnet coreless axial flux generators.

[0145] Each generator 21 is arranged to rotate about the capsule axis of rotation and relative to the capsule housing 10. The generator 21 can rotate freely and independently of the rotation of the energy generation capsule 3.

[0146] In the embodiment shown, a support 23 is provided within the housing 10, coaxial with the rotation axis RA. The support 23 is connected to the housing 10 via bearings 33 that allow the support 23 to rotate about the rotation axis RA independent and relative to the capsule housing 10. In the example embodiment, the support 23 comprises circular end members with three rods extending therebetween, but in alternative embodiments the support may have many other forms. For example, the support 23 may consist of a cylindrical member that is coaxial with the rotation axis.

[0147] The generators 21 are each connected to the support 23 via a hanger 25 which is fixed to the support 23 such that the generators 21 hang from the support 23 under gravitational force. The weight of the generators 21 and the hangers 25 and the free-spinning nature of the support 23 means that the generators 21 generally remain in a lower portion of the energy generation capsule throughout each revolution of the housing 10 as the capsule rotates and moves along the guide surfaces 5, 7. In embodiments where a ballast is include, the ballast may further contribute to forces urging the generators 21 to generally remain in a lower portion of the energy generation capsule throughout each revolution of the housing 10.

[0148] Each generator 21 comprises a drive shaft 27 to drive the generator. The drive shafts 27 are parallel to and offset from the rotation axis RA of the capsule 3. Each drive shaft 27 is coupled to the capsule housing 10 such that relative rotation of the housing 10 with respect to the generator drives rotation of the drive shaft 27.

[0149] In the embodiment shown, a pinion 29 is provided on or coupled to each drive shaft 27 and configured to mesh with a complementary annular gear 31 that is provided internally, adjacent a respective end of the capsule housing. The annular gears 31 are fixed to the housing 10 and rotate in unison with the housing.

[0150] In other embodiments, each drive shaft 27 of the generator 21 may be otherwise coupled to the capsule housing 10. For example, in some embodiments, a belt drive may be provided between the housing drive shaft 15 and the generator 21, for example, with a larger gear provided on an internally protruding portion of the housing drive shaft 15 and a small gear on each generator drive shaft 27.

[0151] During operation, as the energy generation capsule 3 rotates, the annular gears 31 also rotate while the drive shafts 27 remain at a generally fixed orbital position due at least in part to the generator hanging under its own weight. This relative movement between the annular gears 31 and the drive shafts 27 causes the pinion gears 29 to rotate, in turn driving the generators 21 to generate an electric current.

[0152] In some embodiments, the pinions 29 may be coupled to the drive shafts 27 via a clutch (not shown) to prevent rotation of the drive shaft being dampened by slowing rotation of the energy capsule 3. The clutch may be any suitable clutch that disengages when the rotational velocity of the driving body is less than that of the driven body. For example, a sprag clutch or freewheel.

[0153] In some embodiments a flywheel 37 may be provided to smooth the power generation throughout the wave cycles. The flywheel 37 may be helpful to store rotational kinetic energy when the energy generation capsule is rotating at its fastest, for the generators 21 to utilise when the rotational speed of the capsule 3 drops, for example when the energy generation capsule is transitioning between the upper and lower guide rails 5, 7.

[0154] The flywheel 37 may be operatively coupled to each generator drive shaft 21. In some embodiments the flywheel 37 may be provided on the drive shaft. In the embodiment shown, a single flywheel 37 is rotatably mounted about the central support 23 via bearings such that the flywheel can freely rotate about the support 23, independent of rotation of the support 23 and at a speed that may be greater than the rotational speed of the drive shaft 27. The flywheel is coupled to each generator drive shaft 27 via a respective belt drive 39 or gearing.

[0155] In some embodiments where a ballast is required, that ballast may be included as a flywheel.

[0156] Current generated by the apparatus 3 must be transferred out of the housing to be utilised. In the embodiment shown, there is an export cable 15 for transferring current generated by the generators out of the housing 10. Internally, the cable passes through central openings 38 in the support member 23, along the capsule axis of rotation RA. The cable also exits the housing 10 along the capsule axis of rotation in a manner such that the energy generation capsule can rotate relative to the cable 15.

[0157] The point where the cable 15 exits the housing 10 is sealed to prevent the ingress of water into the housing 10. For example, a slip ring 35 may be provided embedded in the respective drive axle 9 to seal the exit point while still allowing rotation.

[0158] The cable 15 leads away from the generation unit and is sufficiently long such that it does not constrain the operation of the apparatus 1. The export cable 15 may link to a mains cable to carry power to the shore, or it may connect directly to a power storage device. In some embodiments, a tightly-coiled electrical cable may be used to allow the necessary slack. Also, in some embodiments, there may be an export cable on both sides of the generation capsule to balance the resulting resistance effect of the cables (possibly one of them not being functional but providing redundancy capacity as a spare).

[0159] Water Treatment and Desalination Apparatus

[0160] In some embodiments of the apparatus 1, the energy generation capsule 3 may comprise a water treatment apparatus such as a water filter or desalination apparatus 103 that utilises the rotational kinetic energy of the capsule to operate a pump and filter.

[0161] The water treatment apparatus 103 may be rotationally driven in the same manner as described above in relation to the electrical power generation embodiment of the energy generation capsule, in conjunction with the apparatus shown in Figures 1 to 4, or it may be rotationally driven using an alternative apparatus or method.

[0162] Figures 7 to 9 illustrate one exemplary embodiment desalination apparatus 103 to desalinate saltwater, for operation in saltwater marine environments and which is described herein. Figure 10 shows an alternative embodiment apparatus 212. In the embodiment of Figure 10, unless otherwise stated like reference numbers are used to describe like features present in the embodiment of Figures 7 to 9, but with the addition of 100. It is anticipated that further embodiments may include some features from the embodiment of Figures 7 to 9 and some features from the embodiment of Figure 10.

[0163] The apparatus 212 comprises an internal energy recovery device (not shown) rather than shaped waste outlets. The waste brine therefore leaves the apparatus at a lower pressure.

[0164] The desalination apparatus 103 includes a housing 110, with a pump 121 and a reverse osmosis desalination filter 122 provided within the housing 110. In some embodiments, the apparatus includes a single desalination filter 122, in other embodiments a plurality of desalination filters 222 may be provided.

[0165] The housing 110 is configured to rotate about an axis of rotation RA' and relative to the pump 121 and the filter 122, the relative rotation acting to operate the pump 121, as will be described in more detail below. The filter 122 is in fluid communication to the pump 121 such that the pump 121 can drive or draw fluid through the filter 122.

[0166] The housing 110 defines an internal reservoir 114 that is in fluid communication with an inlet 124 to the pump 121. The reservoir 114 is configured to receive and hold seawater for desalination. In the embodiment shown, the housing 110 comprises a plurality of inlets 116 to allow the ingress of saltwater into the reservoir.

[0167] In the example embodiment, the housing 110 is generally cylindrical with two end walls Illa, 111b. The inlets comprise a plurality of apertures 116 in the two end walls Illa, 111b of the housing 110. Water permeable filters or fine grills are provided over each aperture 116 to allow seawater to enter the housing 110 through the apertures 116 while preventing the unwanted ingress of debris or marine life into the reservoir 114.

[0168] The apertures 116 may be one-way water permeable to enable water to flow into but not out of the housing 110. The apertures 116 may be non-permeable to air to prevent the ingress of air into the housing when the apertures 116 are above the water surface. For example, each aperture 116 may comprise a one-way valve such as an umbrella or mushroom or diaphragm valve, other suitable valves, or a combination thereof. The housing may additionally or alternatively include apertures in or protruding flanges on the cylindrical wall of the housing 110 to further assist with the ingress of water into the reservoir 114. In the embodiment shown, one or more closable apertures 118 are provided in the cylindrical wall of the housing 110. These apertures 118 are selectively openable and may be helpful to allow the reservoir 114 to be primed by filling it with seawater via these apertures during installation. The apertures 118 can then be sealed using a bung or other cover during operation.

[0169] Additionally, or alternatively, the closable apertures 118 may be used as maintenance hatches to facilitate servicing of internal components.

[0170] The reservoir 114 may be configured to have a capacity that ensures the apparatus is at a desired operational mass when the reservoir is full or near-full. That is, the reservoir may operate as a ballast in some embodiments.

[0171] An internal casing 112 is provided within the housing 110, containing the pump and the filter and fixed relative to the pump 121 and the desalination filter 122. The internal casing 112 is rotatably mounted within the housing 110 such that there is relative rotation between the housing and the internal casing.

[0172] In the embodiment shown, the internal casing comprises a cylindrical body that is concentric with the cylindrical body of the housing 110. However, in alternative embodiments, the casing may have other shapes.

[0173] The internal casing 112 is sealed to prevent the ingress of water from the reservoir 114 into the casing, thereby protecting the exteriors of the pump 121, filter 122, and the drive coupling 139 (described below) from exposure to saltwater and contributing to the buoyancy of the capsule when submerged.

[0174] The internal casing 112 is rotatable about the rotation axis RA'. In the embodiment shown, the apparatus 103 includes a central support 123 along the rotation axis RA'. The internal casing 112 is rotatably mounted to the central support such that it is free to rotate about the central support 123 generally independently of the housing 110.

[0175] In the embodiment shown, the central support 123 comprises a shaft that is coaxial with the two drive axels 113. The shaft 123 extends longitudinally within the apparatus 103 and internal casing 112, between the two drive axles 113. However, other forms of the central support are envisaged. For example, the central support 123 is shown as a single body that extends between the two ends of the housing, but alternatively the central support may comprise a first support portion at a first end of the housing 110, and a second support portion at a second end of the housing. In other embodiments, the central support 123 may comprise several parallel tubes or struts parallel with but offset from the rotation axis RA'.

[0176] In the embodiment shown, the central support 123 is fixed relative to the housing 110 such that it rotates in tandem with the housing. The central support 123 may be fixed to the housing 110 or integrally formed with the housing 110, for example.

[0177] In alternative embodiments, the central support 123 may be rotatably mounted relative to the to the housing 110, for example via a drive coupling such as a belt drive and variable transmission system, such that rotation of the housing 110 at a first rotational velocity causes rotation of central support 123 at a second, different, rotational velocity.

[0178] In the embodiment shown, the central support 123 extends through apertures in the end walls 128 of the internal casing 112. The internal casing 112 is mounted to the central support 123 at the end wall apertures via sealed waterproof bearings 130 to enable rotation between the internal casing 112 and the central support 123, while preventing the ingress of water into the internal casing 112.

[0179] The pump 121 is arranged such that it is free to rotate about the axis of rotation RA'. The pump 121 can rotate freely and generally independently of the rotation of the housing 110 and the central support 123. The pump 121 may be arranged to hang below the axis of rotation RA' under gravitational force acting on the mass of the pump.

[0180] The filter 122 may also be arranged such that it is free to rotate about the axis of rotation RA'. The filter 122 may rotate freely and generally independently of the rotation of the housing 110. The filter 122 may be arranged to hang below the axis of rotation RA' under gravitational force acting on the mass of the filter.

[0181] The pump 121 and filter 122 may be connected such that they move in tandem and there is no relative rotation between the pump 121 and filter 122, as is the case in the exemplary embodiment. The pump 121 and filter 122 may additionally be fixed relative to the internal casing 112 such that they rotate in tandem about the rotation axis RA' with the internal casing 112. Alternatively, the filter 122 may be coaxial with the rotation axis RA'. It may rotate with the internal casing, or it may be fixed relative to the central support 123 and housing 110. In the embodiment shown, the pump 121 is arranged upstream of the filter 122. In this embodiment, the pump 121 comprises an inlet 124 arranged to draw in saltwater, and an outlet 126 to deliver the saltwater to the filter 122.

[0182] The pump inlet 124 is in fluid communication with the reservoir 114. The pump is operable to draw saltwater from the reservoir and deliver it to the desalination filter 122. In the embodiment shown, the pump inlet 124 comprises a short length of tubing leading to an aperture in the casing. The pump 121 is in fluid communication with the reservoir 114 via the aperture in the wall of the casing. The inlet tubing 124 may be integral with the internal casing or fixed to the casing 112. The connection between the pump inlet 124 and the internal casing 112 may fix the relative positions of the pump 121 and internal casing.

[0183] In alternative embodiments, the pump 121 may be arranged downstream of the filter 122 and operable to draw fluids through the filter. In such an embodiment, the filter inlet would be in fluid communication with the reservoir 114.

[0184] The pump 121 is operatively coupled to the housing 110 via a drive coupling 139 such that rotation of the housing 110 drives operation of the pump 121. The pump comprises a drive shaft that is parallel with and offset from the axis of rotation RA'. In the embodiment shown, the drive coupling 139 acts between the central support 123 and the pump drive shaft.

[0185] The drive coupling 139 may comprise any suitable drive or gear arrangement, for example a belt drive (Figure 8) or other gear assembly (such as the sun and pinion gear assembly 239 of Figure 10). The drive coupling 139 is preferably a step-up type mechanism that produces an increased the rotational output speed compared to the input rotational speed. In the example embodiment, the rotation of the central support is the input driving the drive coupling, and the rotational input speed (revolutions per minute) of the central support is less than the rotational output speed (revolutions per minute) of the drive coupling and thereby the pump drive shaft.

[0186] The drive coupling 139 may include a clutch to prevent the rotation of the pump drive shaft being dampened by slowing rotation of the housing 110. The clutch may be any suitable clutch that disengages when the rotational velocity of the pump drive shaft is higher than the rotational velocity at the output of the drive coupling 139. For example, the clutch may comprise a sprag clutch or a freewheel. In operation, as the housing 110 rotates about the rotation axis RA', the internal casing 112 generally maintains its absolute rotational orientation as it is not coupled for rotation with the housing 110. The combined self-weight of the internal casing 112, pump 121, filter 122, any ballast, and other internal components attached thereto mean those components remain at a generally fixed absolute orbital position relative to the rotation axis RA' throughout full rotations of the housing 110. In practice, there may be some slight rotational movement of the internal casing 112 due to inertial force, particularly near the top and bottom of each wave cycle stroke.

[0187] As the housing 110 rotates, the input gear of the drive coupling 139 also rotates in tandem with the central support member 123. The drive shaft of the pump 121 remains at a generally fixed absolute orbital position. The drive coupling comprises an output, for example an output gear, that is coaxial with the pump drive shaft and this relative movement between the input gear of the drive coupling 139 and the pump drive shaft causes the drive coupling output to spin the pump drive shaft, to operate the pump.

[0188] The pump 121 may be any suitable pump for driving or drawing water through the selected desalination filter 122. Preferably, the pump is a high-pressure pump. In one example, the pump may have a pressure rating between 60psi and lOOOpsi. In one embodiment, the pump is a 60 psi pressure pump. In an alternative embodiment, the pump is an 800 psi pump. However, pumps having higher or lower pressure ratings may be used in other embodiments.

[0189] During operation, the pump 121 draws in saltwater from the reservoir 114 in the housing 110, through the pump inlet 124. It then pumps this saltwater at the required pressure into and through the reverse osmosis desalination filter 122 via the pump outlet 126.

[0190] The filter 122 is a reverse osmosis desalination filter.

[0191] The filter has an inlet 132 that is configured to receive saltwater. The filter 122 is in fluid communication with the pump 121 and the reservoir 114. In the embodiment shown, the filter inlet is connected to the pump outlet 126 directly or via a conduit such that the filter inlet 132 is in fluid communication with the reservoir 114 via the pump 121.

[0192] The filter comprises a primary outlet 134 for the provision of desalinated 'fresh' water. The primary outlet 134 is fluidly coupled to a lumen (not shown) such as a hose, conduit, or channel to convey desalinated water out of the apparatus. Typically, the lumen supplying the fresh water extends at least partly along the rotation axis RA'. In the embodiment shown, the central support shaft 123 is hollow and the lumen for conveying the desalinated water is provided within the central support shaft 123 and extends linearly along the central support 123. In other embodiments, a fluid slip-ring may be provided about the lumen to seal the exit point while still allowing rotation.

[0193] The lumen supplies fresh water to an apparatus exit point at the end of one of the drive axels 113 on the rotation axis RA'. A rotating swivel hose link may be provided at the exit point to facilitate coupling to an export conduit in a manner that doesn't hinder rotation of the apparatus 103.

[0194] The export conduit has a form and configuration that provides slack to allow for the apparatus to rise and fall, for example as it rolls along the guide surfaces 7, without risk of the export conduit becoming entangled with the apparatus 103. In some embodiments the export conduit may comprise a coiled conduit. The export conduit may be weighted to ensure the conduit extends down from the apparatus. The export conduit may extend downwards and / or outwards from the apparatus 103.

[0195] It is desirable that the export conduit and coupling swivel link exerts minimal forces on the apparatus so as to not interfere with its rotation, movement and operation. However, in some embodiments where negligible forces are not achievable, a counterbalance or 'dummy' system may be provided on the opposite drive axel 113 to balance the effect.

[0196] The export conduit may be further attached to piping to convey the fresh water to a delivery point, for example to an onshore location or onboard a vessel.

[0197] In the production of desalinated freshwater, the apparatus will also produce a volume of waste brine. The filter 122 comprises one or more secondary outlets 136 for conveying the waste brine from the apparatus.

[0198] The volume of waste brine produced will typically be greater than the volume of freshwater and the outlets 134, 136, 136a, 136b should be sized accordingly. In one embodiment, the water exiting the filter 122 is about one part freshwater to 5 parts brine. However, this ratio may change depending on the filter characteristics.

[0199] In the embodiment shown, the filter outlet 136 is bifurcated into two limbs 136a, 136b to convey brine to opposite ends of the apparatus 103. Each limb 136a, 136b is in fluid connection with an outlet at a respective end of the apparatus. In the embodiment shown each limb 136a, 136b comprises a conduit that is fluidly coupled to a lumen (not shown) such as a hose, conduit, or channel to convey desalinated water within the central support and out of the apparatus. Typically, the lumens for the brine extend at least partly along the rotation axis RA'.

[0200] The housing ends Illa, 111b may comprise internal channels to receive the brine. These channels are in fluid communication with the outlet limbs 136a, 136b and the lumens connected thereto. In the embodiment of Figures 7 and 8, the housing ends Illa, 111b each comprise a hollow shell defining inner circular channel, an outer circular channel, and a number of curved radial channels extending therebetween to allow the passage of brine from the inner channel to the outer channel. However, it will be understood that other channel arrangements are possible. For example, the channels may be curved pipes attached to the housing 110 rather than integrally formed.

[0201] A plurality of tangential waste outlets 140 extend from the periphery of each housing end Illa, 111b for dispersing waste brine out of the apparatus. These outlets 140 are in fluid communication with the radial channels provided in the respective housing end and thereby in fluid communication with the filter brine outlet 136.

[0202] The waste outlets 140 may extend in or be directed to a tangential direction that is opposite to the direction of rotation of the housing to assist with energy capture. This means that waste fluid travelling through the curved channels and exiting the outlets 140 induces a torque on the apparatus 103 that is in the rotation direction, thereby assisting with rotation of the apparatus rather than hindering it and advantageously avoiding the need for excess energy to be used to pump the desalinated water ashore and to disperse the energy of the discharge brine to avoid endangering marine life with a forceful discharge stream.

[0203] In the embodiment shown, the tangential outlets 140 are rigid hollow cylindrical members, but they may have other forms. For example, the outlets 140 may comprise a flexible member or nozzle or may simply comprise apertures in the walls of the housing ends. The apparatus may comprise any suitable number of outlets, which may depend on the size of the apparatus and the volume of waste fluid that is produced. The apparatus is exemplified with eight outlets at each housing end, but other embodiments may have more or fewer outlets. In some embodiments only a single outlet may be provided at one or both ends.

[0204] In an alternative embodiment, the apparatus may include an energy recovery device within the internal casing, to receive and draw energy from the flow of waste brine from the pump. The waste brine may be directed to the energy recovery device within the internal casing. Examples of mechanisms that may be utilised as an energy recovery device include a Clark pump, a Pelton turbine, a turbocharger, a pressure exchanger or work exchanger, a pressure intensifier, an isobaric pressure exchanger, a pressure amplifier or a water hydraulic pump motor or other type of suitable energy recovery device that would be apparent to a skilled person.

[0205] In embodiments having an internal energy recovery device, secondary waste brine coming from the energy recovery device could be directed out of the housing waste outlets. The waste outlets may have an alternative form to the tangential outlets described above as the waste from the energy recovery device would be at a lower pressure.

[0206] An internal surface of the housing 110 may include fins 142 or other features that protrude into the reservoir to induce drag forces on the water to minimise the rotation of the fluid contained in the housing relative to the housing 110. In the embodiment shown, the fins comprise eight flat elongate members that extend between the housing ends 1112, 111b. However, in other embodiments the fins may have other forms or there may be more or fewer fins.

[0207] Together, the reservoir and the fins and the water contained in it 142, additionally act as a flywheel providing rotational inertia to preserve rotational momentum and thereby to smooth the operating speed of the pump 121.

[0208] As described above in relation to the general description of the energy generation capsule 3, the desalination apparatus 103 is a buoyant body. The volume and weight of the desalination apparatus 103 is selected such that the apparatus weighs between about 10% and about 80% of the weight of an equivalent displaced volume of saltwater. In some embodiments, the volume and weight of the apparatus 103 is selected to weigh between about 40% and about 60% of the weight of an equivalent displaced volume of saltwater. In the present example, the apparatus weighs about 50% of the weight of an equivalent displaced volume of saltwater.

[0209] Preferred embodiments of the invention have been described by way of example only and modifications may be made thereto without departing from the scope of the invention.

Claims

CLAIMS1. A wave powered apparatus for generating rotational mechanical energy, the apparatus comprising a buoyant energy generation capsule and upper and lower inclined guide surfaces arranged to restrain and guide movement of the energy generation capsule, the apparatus configured to be partly submerged in a body of water; wherein the energy generation capsule is configured to roll in a unidirectional manner about a capsule axis of rotation, along the guide surfaces as it rises in response to forces from waves in the body of water and lowers in response to gravitational force.

2. An apparatus as claimed in claim 1, wherein the upper and lower guide surfaces are spaced apart and face each other.

3. An apparatus as claimed in claim 1 or 2, wherein the upper and lower guide surfaces are substantially parallel.

4. An apparatus as claimed in any preceding claim, comprising two pairs of upper and lower guide surfaces, and wherein the generation capsule comprises two coaxial drive axles, each drive axle arranged to roll along one of the pairs of upper and lower guide surfaces thereby causing rotation of the generation capsule about the capsule axis of rotation.

5. An apparatus as claimed in claim 4, wherein each drive axle comprises an engagement portion for engaging the respective upper and lower guide surfaces in turn, the engagement portion comprising a grip enhancing feature for reducing slip between the drive axle and the respective guide surfaces.

6. An apparatus as claimed in claim 5, wherein the grip enhancing feature comprises an elastomeric surface.

7. An apparatus as claimed in any preceding claim, wherein the upper and lower guide surfaces comprise a grip enhancing surface.

8. An apparatus as claimed in claim 7, wherein the grip enhancing surface comprises a knurled surface.

9. An apparatus as claimed in any preceding claim, wherein an incline angle of the upper and lower inclined guide surfaces is adjustable.

10. An apparatus as claimed in any preceding claim, wherein motion of the energy generation capsule is guided by the upper guide surface(s) as the capsule rises and by the lower guide surface(s) as it lowers.

11. An apparatus as claimed in any preceding claim, wherein the apparatus is anchored or tethered to the seabed or ground or to a natural feature, or is provided on a fixed or moveable structure or vehicle.

12. An apparatus as claimed in any preceding claim, wherein the apparatus is partly submerged in a body of water at a height such that a majority of the upper and lower guide surfaces are positioned above a wave trough height, and a majority of the upper and lower guide surfaces are positioned below a wave crest height.

13. An apparatus as claimed in claim 12, wherein the height and / or incline of the guide surfaces is adjustable.

14. An apparatus as claimed in claim 12, wherein the height and / or incline of the guide surfaces is fixed.

15. An apparatus as claimed in any preceding claim, wherein the volume and weight of the energy generation capsule is selected such that it weighs between about 10% and about 80% of the weight of an equivalent volume of displaced water.

16. An apparatus as claimed in claim 15, wherein the volume and weight of the energy generation capsule is selected such that it weighs between about 40% and about 60% of the weight of an equivalent volume of displaced water.

17. An apparatus as claimed in any preceding claim comprising a ballast.

18. A wave powered apparatus for generating electrical energy, comprising the apparatus as claimed in any one of claims 1 to 17, wherein the energy generation capsule comprises a generator having a drive shaft, and a housing; wherein the generator is rotatable about the capsule axis of rotation relative to the housing; and wherein relative rotation of the generator drives rotation of the drive shaft to generate electrical energy.

19. An apparatus as claimed in claim 18, comprising a pinion operatively coupled to the drive shaft and a complementary annular gear provided internally in the housing andarranged to rotate with the housing, wherein rotation of the housing causes rotation of the pinion.

20. An apparatus as claimed in claim 19, wherein the pinion is coupled to the drive shaft via a clutch.

21. An apparatus as claimed in claim 20, wherein the clutch is a sprag clutch.

22. An apparatus as claimed in any one of claims 18 to 21, wherein the generator is arranged to hang from a support, the support arranged to rotate about the capsule axis of rotation and relative to the housing, such that a major part of the generator remains in a lower portion of the energy generation capsule as the capsule rotates.

23. An apparatus as claimed in any one of claims 18 to 22, wherein the generator is an alternator.

24. An apparatus as claimed in any one of claims 18 to 23, wherein the drive shaft is parallel and offset from the capsule axis of rotation.

25. An apparatus as claimed in any one of claims 18 to 24, wherein the drive shaft is coupled to a flywheel.

26. An apparatus as claimed in any one of claims 18 to 25, comprising a cable for transferring electricity generated by the generator out of the energy generation capsule.

27. An apparatus as claimed in claim 26, wherein the cable exits the housing along the capsule axis of rotation.

28. A desalination apparatus, comprising the energy generation apparatus as claimed in any one of claims 1 to 17, wherein the energy generation capsule comprises: a housing; a pump arranged within the housing; and a reverse osmosis filter fluidly connected to the, and having an inlet to receive saltwater, and an outlet for the provision of desalinated water; wherein the pump and filter are rotatable relative to the housing about the capsule axis of rotation; and wherein relative rotation between the housing and the pump and filter drives the pump to draw or drive saltwater through the reverse osmosis filters.

29. A desalination apparatus as claimed in claim 28, wherein the housing comprises or defines a reservoir for saltwater, and the pump is fluidly coupled to the reservoir.

30. A desalination apparatus as claimed in claim 29, wherein the housing comprises a plurality of inlets to allow the ingress of saltwater into the reservoir.

31. A desalination apparatus as claimed in any one of claims 28 to 30, wherein the apparatus comprises an internal casing within the housing, containing the pump and the filter and fixed relative to the pump and filter, and wherein the housing is rotatable relative to the internal casing.

32. A desalination apparatus as claimed in 31, wherein the internal casing is watertight.

33. A desalination apparatus as claimed in claim 31 or 32, wherein the pump comprises an inlet arranged to draw saltwater through an aperture in the internal casing.

34. An desalination apparatus as claimed in any one of claims 28 to 33, wherein the at least a major part of pump and filter are suspended below the axis of rotation under gravitational force.

35. A desalination apparatus as claimed in any one of claims 28 to 34, wherein the pump comprises a drive shaft and a drive coupling is provided to operatively couple to the housing to the pump drive shaft; wherein rotation of the housing thereby causes rotation of the drive shaft.

36. A desalination apparatus as claimed in claim 345, wherein the drive coupling is coupled to the drive shaft via a clutch.

37. A desalination apparatus as claimed in any one of claims 34 to 36, comprising a central support along the rotation axis and fixed for rotation with the housing, wherein the drive coupling couples the pump to the central support.

38. A desalination apparatus as claimed in any one of claims 28 to 37, wherein the filter outlet is fluidly coupled to a hose or other conduit that exits the apparatus along the rotation axis, to convey desalinated water out of the apparatus.

39. A desalination apparatus as claimed in any one of claims 28 to 38, wherein the reverse osmosis filter comprises one or more secondary outlets for conveying waste brine from the apparatus.

40. A desalination apparatus as claimed in claim 39, wherein the housing comprises a plurality of curved waste outlets in fluid communication with the one or more secondary outlets from the reverse osmosis filter, for dispersing waste brine out of the apparatus, sized and arranged such that fluid exiting the tangential outlets induces a torque on the generation capsule in the rotation direction.

41. A desalination apparatus as claimed in claim 39, wherein the housing comprises a plurality of tangential waste outlets in fluid communication with the one or more secondary outlets from the reverse osmosis filter, for dispersing waste brine out of the apparatus.

42. A desalination apparatus as claimed in claim 41, wherein the tangential outlets are orientated in the opposite direction to a unidirectional rotation direction of the generation capsule, such that fluid exiting the tangential outlets induces a torque on the generation capsule.

43. An apparatus for generating electrical energy, comprising:A housing configured to rotate about an axis of rotation; and an electrical generator arranged within the housing; wherein the housing is rotatable relative to the electrical generator; and wherein the housing and the electrical generator are coupled via a drive coupling such that rotation of the housing relative to the electrical generator drives the electrical generator to thereby generate electrical energy.

44. An apparatus as claimed in claim 43, wherein the electrical generator is arranged to allow for orbital movement of the generator about the axis of rotation.

45. An apparatus as claimed in claim 43 or 44, wherein a major part of the electrical generator is arranged to be suspended below the axis of rotation under gravitational force.

46. An apparatus as claimed in claim 45, wherein the electrical generator is arranged to hang below the axis of rotation under gravitational force throughout full rotations of the housing.

47. An apparatus as claimed in any one of claims 43 to 46, wherein the generator is arranged to hang from a support and the support is arranged to rotate aboutthe axis of rotation and relative to the housing.

48. An apparatus as claimed in any one of claims 43 to 47, wherein the electrical generator comprises a drive shaft and the drive coupling comprises a pinion operatively coupled to the drive shaft, and a complementary annular gear provided internally in the housing and arranged to rotate with the housing; wherein rotation of the housing thereby causes rotation of the pinion.

49. An apparatus as claimed in claim 48, wherein the pinion is coupled to the drive shaft via a clutch.

50. An apparatus as claimed in claim 49, wherein the clutch is a sprag clutch.

51. An apparatus as claimed in any one of claims 48 to 50, wherein the drive shaft is parallel and offset from the axis of rotation.

52. An apparatus as claimed in any one of claims 43 to 50, wherein the electrical generator is an alternator.

53. An apparatus as claimed in any one of claims 43 to 52, further comprising a flywheel to smooth power generation.

54. An apparatus as claimed in any one of claims 43 to 53, comprising a cable for transferring electricity generated by the generator out of the housing.

55. An apparatus as claimed in claim 54, wherein the cable exits the housing along the axis of rotation.

56. An apparatus as claimed in any one of claims 43 to 55, wherein the housing includes two coaxial drive axles along the axis of rotation, and the drive axles are configured to roll along guide surfaces to induce rotation of the housing.

57. An apparatus as claimed in any one of claims 43 to 56, wherein each drive axle comprises an engagement portion having a grip enhancing feature for engaging and reducing slip between the drive axles and the guide surfaces.

58. An apparatus as claimed in claim 57, wherein the grip enhancing feature comprises an elastomeric surface.

59. An apparatus as claimed in any one of claims 43 to 58, wherein the apparatus is for use in a body of water and the housing is sealed to prevent the ingress of water.

60. An apparatus as claimed in claim 59, wherein volume and weight of the apparatus is selected such that weighs between about 10% and about 80% of the weight of an equivalent displaced volume of water from the body of water.

61. An apparatus as claimed in claim 60, wherein the volume and weight of the energy generation capsule is selected such that weighs between about 40% and about 60% of the weight of an equivalent displaced volume of water from the body of water.

62. An apparatus as claimed in any one of claims 43 to 61, comprising a ballast.

63. A desalination apparatus, comprising: a housing configured to rotate about an axis of rotation; a pump arranged within the housing; and a reverse osmosis filter fluidly connected to the pump, and having an inlet to receive saltwater, and an outlet for the provision of desalinated; wherein the housing is rotatable relative to the pump and the filter; and wherein the housing and the pump are coupled via a drive coupling such that rotation of the housing relative to the pump drives the pump to draw or drive saltwater through the filter.

64. A desalination apparatus as claimed in claim 63, wherein the housing comprises or defines a reservoir for saltwater, and the pump is fluidly coupled to the reservoir.

65. A desalination apparatus as claimed in claim 64, wherein the housing comprises a plurality of inlets to allow the ingress of saltwater into the reservoir.

66. A desalination apparatus as claimed in claim 655, wherein the inlets comprise filters or grills to prevent the ingress of debris and / or air into the reservoir.

67. A desalination apparatus as claimed in any one of claims 64 to 66, wherein the apparatus comprises an internal casing within the housing, the internal casing containing the pump and the filter and being fixed relative to the pump and filter, and wherein the housing is rotatable relative to the internal casing.

68. A desalination apparatus as claimed in claim 67, wherein the internal casing is sealed to prevent the ingress of water into the casing.

69. A desalination apparatus as claimed in claim 67 or 68, wherein the pump comprises an inlet arranged to draw salt water through an aperture in the casing.

70. A desalination apparatus as claimed in any one of claims 63 to 69, wherein the pump and filter are arranged to allow for orbital movement of the pump and filter about the axis of rotation relative to the housing.

71. A desalination apparatus as claimed in any one of claims 63 to 70, wherein the pump is arranged to hang below the axis of rotation under gravitational forces.

72. A desalination apparatus as claimed in any one of claims 63 to 71, wherein the filter is arranged to hang below the axis of rotation under gravitational forces.

73. A desalination apparatus as claimed in any one of claims 63 to 72, wherein the pump is arranged to hang below the axis of rotation under gravitational forces throughout full rotations of the housing.

74. A desalination apparatus as claimed in any one of claims 63 to 73, wherein the pump comprises a drive shaft and the drive coupling comprises a belt drive or other gear assembly operatively coupled to the housing and to the pump drive shaft; wherein rotation of the housing thereby causes rotation of the drive shaft.

75. A desalination apparatus as claimed in claim 74, wherein the drive coupling is coupled to the drive shaft via a clutch.

76. A desalination apparatus as claimed in claim 75, wherein the clutch is a sprag clutch.

77. A desalination apparatus as claimed in any one of claims 74 to 76, wherein the drive shaft is parallel and offset from the axis of rotation.

78. A desalination apparatus as claimed in any one of claims 63 to 77, comprising a central support along the rotation axis and fixed for rotation with the housing, wherein the drive coupling is attached to the central support.

79. A desalination apparatus as claimed in any one of claims 63 to 78, wherein the filter outlet is fluidly coupled to a hose that exits the apparatus along the rotation axis, to convey desalinated water out of the apparatus.

80. A desalination apparatus as claimed in any one of claims 63 to 79, wherein the filter comprises one or more secondary outlets for conveying waste brine from the apparatus.

81. A desalination apparatus as claimed in claim 80, wherein the housing comprises a plurality of curved waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus, arranged such that fluid exiting the tangential outlets induces a torque on the generation capsule in the rotation direct.

82. A desalination apparatus as claimed in claim 80, wherein the housing comprises a plurality of tangential waste outlets in fluid communication with the one or more secondary outlets from the filter, for dispersing waste brine out of the apparatus.

83. A desalination apparatus as claimed in claim 82, wherein the tangential outlets extend in the opposite direction to a rotation direction of the apparatus, such that fluid exiting the tangential outlets induces a torque on the apparatus in the rotation direction.

84. A desalination apparatus as claimed in any one of claims 63 to 83, wherein the housing includes two coaxial drive axles along the axis of rotation, and the drive axles are configured to roll along guide surfaces to induce rotation of the housing.

85. A desalination apparatus as claimed in any one of claims 63 to 84, wherein each drive axle comprises an engagement portion having a grip enhancing feature for engaging and reducing slip between the drive axles and the guide surfaces.

86. A desalination apparatus as claimed in claim 85, wherein the grip enhancing feature comprises an elastomeric surface.

87. A desalination apparatus as claimed in any one of claims 63 to 86, wherein volume and weight of the apparatus is selected such that weighs between about 10% and about 80% of the weight of an equivalent volume of water from the body of water.

88. A desalination apparatus as claimed in claim 87, wherein the volume and weight of the apparatus is selected such that weighs between about 40% and about 60% of the weight of an equivalent volume of water from the body of water.

89. A desalination apparatus as claimed in any one of claims 63 to 88, comprising a ballast.

Images