GB2522697A

GB2522697A - Wave energy converter

Info

Publication number: GB2522697A
Application number: GB1401828.7A
Authority: GB
Inventors: Geir Arne Solheim
Original assignee: HAVKRAFT AS
Current assignee: HAVKRAFT AS
Priority date: 2014-02-03
Filing date: 2014-02-03
Publication date: 2015-08-05
Anticipated expiration: 2034-02-03
Also published as: NO20140126A1; GB201401828D0; NO342406B1; GB2522697B

Abstract

An Oscillating Water Column OWC wave energy converter 10 includes a plurality of columns 20 which are in fluidic communication via corresponding ports 50 to ocean waves received at the converter 10. The columns 20 have an upwardly tapered cross-section, and are coupled at their upper ends to a power takeoff arrangement 60. The ports 50 are arranged in series along the forward direction 40, and the ports 50 are of progressively greater depth into the ocean environment along the forward direction 40 so as to cause the ocean waves to propagate in a downwardly-directed vortex 45 when received at the ports 50. The columns may be connected to air turbines 60 via poly-cuspid e.g. tri-cuspid valves (figures 4-8) made from Nitrile rubber, polyurethane or silicone rubber. Such valves may have long life in the ocean environment and be used to produce uni-directional flow through a turbine 60.

Description

WAVE ENERGY CONVERTER

Technical Field

The present invention relates to wave energy converters, for example to wave energy converters for generating renewable energy or for absorbing wave energy for providing protection against waves, for example for reducing coastal erosion.

Moreover, the present invention concerns methods of generating renewable energy using aforementioned wave energy converters. Furthermore, the present invention concerns methods of absorbing wave energy using aforementioned wave energy converters. Additionally, the present invention concerns component parts for constructing aforementioned wave energy converters. Additionally, the present invention concerns systems for generating power from ocean waves, wherein the systems include a plurality of aforesaid wave energy converters. Contents of a related patent application PCT/EP2013/002266 are hereby incorporated by reference.

Background

Wave energy converters are known in the art and employ a variety of wave energy conversion mechanisms. However, unlike offshore wind turbines, ocean wave energy converters have not hitherto been deployed in large numbers for providing electrical power to electrical supply networks. A contemporary challenge is to implement aforesaid ocean wave energy converters in a cost effective manner, whilst ensuring that they convert ocean wave energy efficiently to electrical power and also survive severe weather conditions which are occasionally encountered offshore. The challenge thus has associated constraints which can be mutually opposing, for example a robust design of ocean wave converter is potentially more costly to manufacture and deploy in comparison to a less-robust structure.

A robust and efficient wave energy converter is described in a published international PCT patent application no. W02011/162615A2 (PCT/N02011/000175, "Ocean Wave Energy System", Havkraft AS, Geir Solheim). The wave energy converter is implemented as an ocean wave energy system for generating power from ocean waves, wherein the system includes a platform supporting an array of hollow columns whose respective lower ends are in fluidic communication with ocean waves and whose respective upper ends are in air communication with a turbine arrangement such that wave motion occurring at the lower ends is operable to cause air movement within the columns for propelling the turbine arrangement to generate power output. The system further includes one or more position-adjustable and/or angle-adjustable submerged structures near the lower ends of the columns for forming ocean wave propagating in operation towards the lower ends of the columns to couple the waves in a controllable manner into the hollow columns.

In the aforesaid published PCT application no. W02011/162615A2, there is provided a comprehensive overview of wave energy theory which is hereby incorporated by reference. Ocean waves are surface waves substantially at an interface between two fluids, namely ocean water and air. The surface waves propagate substantially within a plane of the interface and are susceptible to being refracted, reflected, transmitted and absorbed at any objects intersecting substantially with the plane of the interface. For the surface waves to be absorbed effectively, the objects must be wave impedance matched to an impedance of the surface waves. When the objects are of a physical size comparable to a wavelength of the surface waves, designing the objects to provide an effective wave impedance match is a complex task, especially when the surface waves in practice have a varying wavelength depending upon ocean weather conditions. In addition, the objects need to be designed to withstand severe storm conditions and also be substantially free of cavitation effects when large amounts of wave energy are being absorbed by the objects. The aforesaid published PCT application describes a wave energy converter which is capable of providing efficient absorption of ocean waves.

However, there arises a need to implement a wave energy converter which is especially efficient at absorbing ocean wave energy whilst also being robust in operation, and cost effective to manufacture. For example, it is desirable that the wave energy converter is manufactured in such a manner which is convenient for contemporary ship yards.

Summary

The present disclosure seeks to provide an improved wave energy converter which is more efficient in operation, more robust and more efficient in its use of construction materials.

According to a first aspect, there is provided a wave energy converter defined in appended claim 1: there is provided a wave energy converter for converting in operation energy conveyed in ocean waves propagating in a forward direction in an ocean environment and received at the converter via an energy pickoff arrangement into generated power, the converter includes a plurality of columns which are in fluidic communication via corresponding ports to the ocean waves received at the converter, wherein the ports are arranged substantially in series along the forward direction, and wherein the pods are of progressively greater depth into the ocean environment along the forward direction so as to cause the ocean waves to propagate in a downwardly-directed vortex when received at the ports, characterized in that one or more of the columns have an upwardly tapered cross-section when in operation, and are coupled substantially at their upper ends to the energy pickoff arrangement.

The invention is of advantage in that the disposition of the plurality of upwardly-tapered ports to create a robust downwardly-directly vortex provides for more efficient wave energy adsorption.

Optionally, for the wave energy converter, the energy pickoff arrangement includes an energy pickoff device for each of the one or more columns.

Optionally, for the wave energy converter, the energy pickoff arrangement includes an energy pickoff device which is shared between a plurality of the columns.

Optionally, for the wave energy converter, the energy pickoff arrangement includes one or more poly-cuspid valves for causing a uni-direction flow of air provided from one or more columns to pass through a turbine for generating power. More optionally, for the wave energy converter, the one or more poly-cuspid valves include at least one tricuspid valve. More optionally, for the wave energy converter, one or more flaps of the one or more poly-cuspid valves are fabricated from a flexible polymeric plastics material. Optionally, one or more flaps of the one or more poly-cuspid valves include a plurality of flexible cords and/or at least one pyramidal-type frame to prevent the one or more flaps from folding further than a mutually abutting arrangement when in a closed state. Yet more optionally, for the wave energy converter, the flexible polymeric plastics material includes at least one of: Nitrile rubber, polyurethane, silicone rubber.

Optionally, for the wave energy converter, the plurality of columns are arranged so that that their elongate axes are substantially aligned along a first direction, and that the ports have corresponding port angles (B) relative to the first direction which are progressively larger as the ports are of progressively greater depth. More optionally, for the wave energy converter, the first direction is substantially a vertical direction when the converter is in operation.

Optionally, for the wave energy converter, the ports have an elliptical, round or rectilinear cross-section.

Optionally, for the wave energy converter, the plurality of columns are operable to couple to the ocean waves received at the ports in a resonant manner.

Optionally, the converter includes in a range of 2 to 10 columns and associated ports arranged in series.

Optionally, for the wave energy converter, one or more of the columns include one or more additional wave energy absorbing devices therein. More optionally, for the wave energy converter, the one or more additional wave energy absorbing devices include at least one piston device.

According to a second aspect, there is provided a wave energy system including a platform defining a peripheral edge thereto, characterized in that a plurality of wave energy converters pursuant to the first aspect are mounted substantially around at least a portion of the peripheral edge to receive ocean waves propagating towards the system at the converters.

According to a third aspect, there is provided a method of converting energy conveyed in ocean waves propagating in a forward direction in an ocean environment when received at a wave energy converter via an energy pickoff arrangement to generate power, characterized in that the method includes: (a) arranging for a plurality of columns of the converter to be in fluidic communication via corresponding ports to the ocean waves received at the converter, wherein one or more of the columns have an upwardly tapered cross-section when in operation, and are coupled substantially at their upper ends to an energy pickoff arrangement; (b) arranging for the columns to be disposed substantially in series along the forward direction; and (c) arranging for the ports to be progressively greater depth into the ocean environment along the forward direction so as to cause the ocean waves to propagate in a downwardly-directed vortex when received at the ports.

Optionally, the method includes arranging the plurality of columns so that that their elongate axes are substantially aligned along a first direction, and that the ports have corresponding port angles () relative to the first direction which are progressively larger as the ports are of progressively greater depth.

Optionally, the method includes using poly-cuspid valves coupled to the one or more columns for causing a substantially uni-directional air flow through at least one turbine to generate power.

According to a fourth aspect, there is provided a wave energy converter for converting in operation energy conveyed in ocean waves propagating in a forward direction in an ocean environment and received at the converter via an energy pickoff arrangement into generated power, the converter includes a plurality of columns which are in fluidic communication via corresponding ports to the ocean waves received at the converter, wherein the ports are arranged substantially in series along the forward direction, and wherein the ports are of progressively greater depth into the ocean environment along the forward direction so as to cause the ocean waves to propagate in a downwardly-directed vortex when received at the ports, characterized in that the energy pickoff arrangement includes one or more poly-cuspid valves for causing a uni-direction flow of air provided from one or more columns to pass through a turbine for generating power.

It will be appreciated that features of the invention are susceptible to being combined in various combinations without departing from the scope of the invention as defined by the appended claims.

Description of the diagrams

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein: FIG. 1 is an illustration of an embodiment of a wave energy converter pursuant to the present invention; FIG. 2 is a schematic side view of the wave energy converter of FIG. 1; FIG. 3 is an illustration of an alternative implementation of a portion of the wave energy converter of FIG. 1; FIG. 4A is an illustration of a configuration of air flow occurring in operation in the wave energy converter of one or more of FIG. 1 to FIG. 3; FIG. 4B is an illustration of an alternative configuration of air flow occurring in operation in the wave energy converter of one or more of FIG. 1 to FIG. 3, wherein a dual turbine arrangement is employ, vented to ambient air; FIG. 5 is an illustration of a tricuspid valve employed in the configuration of FIG. 4; FIG. 6 is an illustration of a quadracuspid valve, namely four-flap valve, employed in the configuration of FIG. 4; FIG. 7 is an illustration of a flexible cord attached to a flap of the quadracuspid valve in the configuration of FIG. 4; FIG. 8A and FIG. 8B are illustrations of a pyramidal-type frame placed onto the valve in the configuration of FIG. 4; and FIG. 9 is an illustration of a system including an arrangement of a plurality of the wave energy converters as illustrated in FIG. 1 to FIG. 3.

In the accompanying diagrams, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.

Description of example embodiments

Referring to FIG. 1, the present disclosure concerns, in overview, a wave energy converter 10 including a plurality of substantially enclosed air columns 20a, 20b, 20c, 20d coupled via a port arrangement 30 into fluidic communication with ocean waves propagating in an ocean in a horizontal forward direction substantially as denoted by an arrow 40. The port arrangement 30 includes port channels 50a, 50b, 50c, 50d coupled at their upper ends to the air columns 20a, 20b, 20c, 20d respectively and also at their lower ends to the ocean waves, wherein the pod channels 50a, 50b, 50c, 50d have their lower ends at progressively greater depths along the forward direction defined by the arrow 40, and have their elongate axis orientation angles at progressively shallower angles along the forward direction defined by the arrow 40 relative to a surface of the ocean; alternatively defined, the port channels 50a, 50b, 50c, 50d have their lower ends at progressively greater depths along the forward direction defined by the arrow 40, and have their elongate axis orientation angles at progressively greater angles B along the forward direction defined by the arrow 40 relative to a substantially elongate vertical axis of the air columns 20a, 20b, 20c, 20d as illustrated in FIG. 2. Optionally, the air columns 20a, 20b, 20c, 20d are operated with their respective elongate axes disposed in substantially a vertical orientation.

Optionally, an energy pickoff device 60, for example an air-propelled turbine, is included at an upper end of each air column 20a, 20b, 20c, 20d, namely remote from the lower ends of the port channels 50a, 50b, 50c, 50d which are directly in communication with the ocean waves. Such a disposition of the lower ends of the port channels 50a, 50b, 50c, 50d results in the ocean waves being progressively decelerated and efficiently absorbed at the converter 10 to generate corresponding energy at the energy pickoff devices 60 at the upper ends of the air columns 20a, 20b, 20c, 20d as the ocean waves are forced to exhibit a downward vortex 45. The port arrangement 30 is implemented to provide an optimal absorption of ocean wave energy, whilst substantially avoiding transmission or reflection of wave energy, and whilst being of a general compact size and therefore efficient in use of construction materials.

Optionally, as illustrated in FIG. 1, the port arrangement 30 is fabricated from planar panels, for example steel panels of a type frequently used for contemporary ship building and offshore constructions. The panels are beneficially cut to suitable size, for example by way of Carbon Dioxide laser cutting, and then assembled, or otherwise joined, together, for example by continuous welding seams formed at interfaces whereat the panels mutually meet. Moreover, the air columns 20a, 2Db, 20c, 20d are beneficially implemented in an upwardly-tapered frusto-conical form as illustrated, wherein an upper diameter C2 is less than a lower diameter Cl, wherein a frusto-conical form is best able to withstand pressure surges in adverse weather conditions occurring within the columns 20a, 2Db, 20c, 2Dd; moreover, a frusto-conical form is beneficially fabricated, for example, in a continuously-welded manner from sheet material, from Carbon-fibre or fibreglass-reinforced composite materials, marine-grade cast concrete materials or any combination of these. Optionally, the air columns 20a, 2Db, 20c, 20d are manufactured to have a polygonal cross-section, for example a rectangular cross-section or hexagonal cross-section. Optionally, the air columns 20a, 2Db, 20c, 20d are manufactured from planar sheet components which are joined together, for example via continuous welding. Conveniently, as illustrated in FIG. 2, the pipes have a diameter Cl in a range of 1 metre to 2 metres, more preferably a diameter in a range of 1.3 metres to 1.9 metres, and most preferably a diameter of substantially 1.6 metres. A taper angle j3 is beneficially in a range of 1° to 20°, optionally in a range of 3° to 15°, and more optionally substantially in a range of 5°tolO°.

The air columns 20a, 2Db, 20c, 20d beneficially have an elongate length L in a range of 1 to 25 metres, and more preferably an elongate length L of substantially 14 metres up to a lower end of the energy pickoff devices 60. Although FIG. 1 and FIG. 2 illustrate four columns 2Da, 20b, 2Dc, 2Dd and an associated port arrangement 3D to suit, there are optionally included two or more columns 20 in the converter ID.

Optionally, for the converter ID, the four columns 2Da, 20b, 20c, 20d and associated port arrangement 30 are implemented as an integral assembly, for example as a mass-produced module.

Referring to FIG. 2, the ports of the port arrangement 30 have an angular disposition of angles Ba, Bb, c, Bd for the columns 20a, 20b, 20c, 20d respectively, relative to an elongate axis of the columns 20a, 2Db, 20c, 20d as illustrated. Optionally, the angles Ba, Bb, B, B of the ports 50a, SOb, 50c, SOd are substantially 100, 30°, 50°, 75° respectively, although other angular dispositions are feasible for implementing the present invention. The air columns 20a, 2Db, 20c, 20d beneficially have a separation distance G, towards a lower portion thereof as illustrated, wherein the distance G is optionally substantially 0.88 metres. Moreover, the port arrangement 30 optionally has a height K and a breadth J as illustrated in FIG. 2, wherein the height K is optionally substantially 8 metres and the breadth J is optionally substantially 10 metres. The port arrangement 30 beneficially has a width, as seen in a direction of Is the arrow 40, of substantially 3 metres. Such sizes for the columns 20a, 20b, 20c, 20d and the port arrangement 30 are approximately comparable to a wavelength of ocean waves which the converter 10 is designed to convert to output power, for example output power from the energy pickoff devices 60. Optionally, the columns 20a, 20b, 20c, 20d and the port arrangement 30 are of size which enables resonant absorption of ocean waves to occur within the converter 10, thereby enhancing conversion efficiency of the converter 10. Optionally, the columns 20a, 20b, 20c, 20d are dynamically tuned in operation, for example by varying their effective length L and/or diameter Cl, C2, for example by using actuated baffles or similar within the columns 20a, 2Db, 20c, 20d. Optionally, this allows a so-called "natural", namely passive, control system operating with the columns 20a, 20b, 20c, 20d as passive gears.

The converter 10 is operable to steer incoming ocean waves approaching in a direction of the arrow 40 into a decelerating downwardly-directed vortex 45 which increases pressure of the vortex 45 with depth into the ocean and hence is especially efficient at extracting ocean wave energy in a relative small volume, without significant reflection or transmission of the ocean waves. Such a manner of operation is fundamentally different to known contemporary ocean wave energy converters. Moreover, a dominating wave direction beneficially steers a natural movement and direction of the converters 10, so that the converters 10 are facing the wave direction with a single point entry, or also called mooring.

The converter 10 is optionally designed to be arranged in arrays, wherein the arrays can be of curved form or linear form depending upon application in a system. For example, in FIG. 3, the port arrangement 30 designed at have a radially tapered form having a taper angle e in a range of 15° to 300, and more optionally substantially 23°, with a length M in an order of 12 metres and widest width W of substantially 6.1 metres, although other sizes for the port arrangement 30 of FIG. 3 are feasible when implementing the present invention. The port arrangement 30 of FIG. 3 is conveniently manufactured by joining planar sheets of material together, for example by way of continuously welding sheet steel components together. Alternatively, the port arrangement 30 can be implemented as a reinforced concrete cast component.

The converter 10 as described in the foregoing is susceptible to being mounted onto various types of platform for implementing ocean wave energy systems.

Alternatively, the converter 10 can be mounted in arrays to provide coastal defences, for example to reduce coastal erosion and/or to create calm ocean conditions in a wake of the arrays, for example for aquaculture and/or for harbour facilities. Similarly, the converter 10 is beneficially mounted onto exiting piers and light houses at sea, and/or along a coast line and/or in rivers and fjords.

Referring next to FIG. 4A, an example implementation of the energy pickoff device 60 is shown. The energy pickoff device 60 is coupled in air communication with an upper end, with a diameter of substantially C2, of its correspondingly upwardly-tapered frusto-conical column 20. Moreover, the energy pickoff device 60 includes a first inlet valve 100 for connecting an interior volume of the column 20 with a first over-pressure chamber 110, and a second outlet valve 140 for connecting the interior volume of the column 20 to a second under-pressure chamber 130; an air turbine 120 is coupled between the first over-pressure chamber 110 and the second under-pressure chamber 130 as illustrated. The valves 100, 140 are operable to seal when there is substantially zero pressure difference thereacross or a reverse pressure thereacross, and the valves 100, 140 are operable to open when there is a forward pressure drop thereacross and/or a forward flow of air therethrough. Optionally, the over-pressure chambers 110 of a plurality of the energy pickoff devices 60 are mutually coupled together. Optionally, the under-pressure chambers 130 of a plurality of the energy pickoff devices 60 are mutually coupled together. Such sharing of the over-pressure chamber 100 and/or the under-pressure chamber 130 enables a more substantially constant air flow through the turbine 120 to be achieved, and potentially reduces cost on account of fewer turbines 120 being required for a plurality of the columns 20. Optionally, the converter 10 includes only a single turbine 120 which is supplied and exhausted with a flow of air from a common over-pressure chamber 110 and a common under-pressure chamber 130, respectively. Moreover, when the turbine 120 is made larger, it is often substantially more efficient at converting energy in an airflow therethrough to rotational energy for driving an electrical generator or similar, in comparison to each column 20 being provided with its own individual turbine 120. In the implementation of FIG. 4, the turbine 120 does not necessarily need to be a bi-directional Wells-type turbine, but can be implemented using a variety of standard types of turbines, for example single flow-direction turbines with fixed blade pitch angle.

Referring to FIG. 4B, there is shown an alternative configuration to that of FIG. 4A, wherein a dual turbine arrangement 120 is employed, exhausted to ambient atmosphere. Optionally, the chambers 110 and/or the chambers 130 of a plurality of columns 20 are mutually coupled, allowing the dual turbine arrangement to address a plurality of such columns 20; a more steady, namely less pulsating air flow, through the dual turbine arrangement is thereby feasible. Each turbine 120 of the dual turbine arrangement is beneficially a uni-directional turbine; in other words, it is not a requirement that the turbines 120 be a Wells-type turbine device, as air-flow therethrough is uni-directional in FIG. 4B. In an alternate embodiment, the dual turbine arrangement 120 acts a switch to allow the so-called "natural", namely passive operation wherein direction of pressure decide to allow air flow.

Referring next to FIG. 5, an example tricuspid valve is shown, namely suitable for implementing one or more of the valves 100, 140. Optionally, the valves 100, 140 are each implemented as an arrangement of a plurality of smaller tricuspid valves.

Tricuspid valves are employed in nature, for example in a human heart which has to beat many millions of times during its lifetime, and yet provide highly reliable operation. In FIG. 5, flaps of the tricuspid valve are denoted by 180A when in a -12-closed state, and are denoted by 180B when in an open state. The flaps 180A, 18DB are optionally implemented using rigid materials, and are hinged, for example with assistance of torsional return springs biasing them to their closed state, where they are coupled to a common base plate; such rigid material includes, for example metal sheet, Aluminium metal sheet, Titanium metal sheet, composite plastics materials, and similar. Alternatively, the flaps 180A, 18DB are fabricated from a polymeric plastics material, for example polyurethane or silicone rubber, and are operable to flex into an open state when a positive pressure is applied across the valves 100, 140; in such an implementation, the flaps 180A, 180B and their base plate are beneficially fabricated as an integral moulded component, thereby reducing manufacturing and maintenance costs. Polyurethane is advantageous to employ for the flaps 180A, 180B, because: (a) it is chemically inert, and thus not corroded by saline water; (b) it is capable of flexing millions of times before suffering effects of work hardening; and (c) it is a strong material, which is capable of withstanding considerable forces applied to the valves 100, 140, for example in storm conditions.

Other flexible polymeric materials are optionally employed for the flaps 180A, 180B, for example Nitrile rubber and similar.

In FIG. 5, the valves 100, 140 are implemented as tricuspid valves, each valve having three flaps 180 which abut together to seal the valves 100, 140 in a closed state, and which mutually separate at their distal free ends when the valves 100, 140 are in an open state. Optionally, the chambers 110, 130 are relatively large air reservoirs. It will appreciated that the valves 100, 140 can be implemented to have more than three flaps, for example as illustrated in FIG. 6, wherein each valve 100, includes four flaps 190, namely a quadracuspid valve The flaps 190 mutually abut, as denoted by 190A, when the valves 100, 140 are in their closed state, subject to reverse pressure, and are separated at their distal ends, as denoted by 190B, when the valves 100, 140 are in their open state, subject to a flow of air through the valves 100, 140. Optionally, one or more valves 100, 140 are implemented with more than four mutually cooperating flaps, for example hexacuspid valves, pentacuspid valves and so forth.

In FIG. 7, each of the flaps 190 are optionally restrained by one or more flexible cords 210 to prevent the flaps 190 from folding beyond a mataully abutting arrangement when the flaps 190 are in a closed state. The one or moreflexible cords 210 are clamped against the column 20 and to the flaps 190; in the closed state, the one or moreflexible cords 210, as denoted by 210A, ensure that the flaps 190A are reliable to form a strong pyramidal type shape when in a closed state, while subject to reverse pressure, the one or moreflexible cords 210, as denoted by 210B, loosens up to allow airflow through the valves 100, 140. Beneficially, the one or more flexible chords 210 are fabricated from materials that are strong and do not work-harden easily or become knotted, for example carbon fibre strands, polypropylene strands or In a further alternative, pyramidal-type frames 220 are placed onto the valve 100, 140 to prevent the flaps 190 from folding beyond a substantially mutually abutting arrangement when the valve 100, 140 is in a closed state. For example, in FIG. 8A, the flaps 190A rest onto the pyramidal-type frames 220 to ensure that the flaps 190A do not fold, when in the closed state. In FIG. 8B, the flaps 190B are in the open state, wherein the pyramidal-type frame 220 does not cause any significant flow reistance to air flowing through the valve 100, 140.

Optionally, the columns 20 include additional energy pickoff devices, for example one or more pistons 240 therein, which can be used in extreme weather conditions to protect the valves 100, 140 and the turbine 120 from pressure surges. Such one or more pistons 240 are beneficially coupled to hydraulic pumps to generate a flow of hydraulic fluid for driving an hydraulic generator or similar.

In FIG. 9, each converter 10 of an ocean wave energy production system 300 is capable in operation, for example in Norwegian, Japanese or Scottish offshore locations, of generating ten's of kiloWatts (kW) of power, such that the system is potentially capable of generating in total an order of 10 MegaWatts (MW) to 500 MegaWatts (MW) of power, namely comparable to a small nuclear reactor but without any risk of radioactive contamination or thermal runaway, and without generating nuclear waste requiring storage for hundreds of thousands of years (as encountered with conventional nuclear power based on a Uranium 235/238 to -14-Plutonium 239 cycle and/or a MOX cycle). Moreover, the system 300 is capable of generating in its wake calmer ocean water which is conducive to supporting aquaculture. Optionally, the system 300 and the power generated is used to generate Hydrogen gas on the system 300, for example via use of electrolysers or other suitable Hydrogen generation equipment. A benefit arising from Hydrogen production in combination with the wave energy is recognised as allowing more flexible installations, where the Hydrogen acts as an energy storage of the system 300 in an event of not being able to collect or retrieve the power generated. In addition the Hydrogen may preferably also be used as the main energy storage from the system 300 as it would not require to have cables or other grid connection for transferring the power from offshore to the shore. This Hydrogen setup which eliminates the use of cables to the shore would cut the CAPEX of the installation with about 20-30%. In addition the use of a combined/hybrid system 300 which beneficially also has wind turbines, such as the Siemens 6 MW, would further lower the CAPEX by a further ca 20-30 %. Moreover, when the system 300 is installed in combination with an aquaculture or fish farm installation, there are further synergetic benefits such as the aquaculture constructions being protected better in more hostile wave conditions. Advantages include much greater potential for aquacuture by opening up the sea, securing both better turn over on water and better salinity, energy production on remote installations without cabling, storage of energy to when they need it, Oxygen as a "waste" from Hydrogen production via electrolysing of water is usable directly in fish farming.

When its service life is complete, the system 300 can be towed into harbour, and its materials recycled for manufacturing other products. Such desirable characteristics render the system an attractive option for sustainable low-Carbon energy production at a cost which is potentially less than a total life-time-cycle cost of generating nuclear power. The system 300 is thus especially suitable for countries such as Japan which are seismically active and thus unsuitable for nuclear power. The system 300 can be deployed in large numbers along a coastline, with spaces therebetween for allowing access to shipping, lifeboats and similar. Moreover, the system 300 can be deployed at distances offshore whereat they do not disfigure the natural beauty of coastlines. Additionally, the system 300 has a relatively low height profile in comparison to offshore wind turbines, and hence does not interfere significantly with coastal radar. The system 300 is capable of being constructed in existing shipyards using known construction techniques, and hence represents an attractive product to manufacture when the demand for offshore oil and gas exploration and production platforms eventually declines in future as a result of depletion of geological fossil oil and gas reserves.

Optionally, the system 300 is provided with one or more submerged structures beneath the converters 10 for providing an optimal absorption of ocean wave energy.

Optionally, the one or more submerged structures are adjustable to provide dynamically controlled absorption, for example favouring certain specific wavelengths of ocean waves. Optionally, the one or more submerged structures are planar in form, and are disposed to enhance generation of the aforesaid vortex 45.

Although the system 300 is described in the foregoing as being implemented as a platform, other implementations are feasible, for example in a form of a ship or boat with a plurality of the converters 10 being disposed in a triangular configuration at a front region of the ship or boat; for example in a range of 3 to 9 converters 10 are disposed at the front region of the ship or boat; in such a configuration, one of the converters 10 is directed in a forwards direction, defined by a pointing direction of an elongate axis of the ship or boat, and one or more other converters 10 are disposed progressively along one or more sides of the ship or boat extending backwards from the front region of the ship or boat. The ship of boat beneficially has a width in a range of 9 metres to 27 metres, and an elongate length in a range of 50 metres to metres, Such an implementation of the system 300 is beneficial, because standard ship or boat-building skills can be employed for implementing the system 300, and the ship or boat can be sailed to a geographical location whereat it is required, for example rapid-deployment energy sources for disaster relief and so forth.

Optionally air movement within the columns 20 is converted to electrical energy using a linear generator, for example implemented by using a piston, float or similar element included within the column to generate mechanical force to drive the linear generator. Optionally, the piston float or similar is in contact with sea water coupled to the columns 20. -16-

Modifications to embodiments of the disclosure described in the foregoing are possible without departing from the scope of the invention as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "consisting of", "have", "is" used to describe and claim the present invention are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present.

Reference to the singular is also to be construed to relate to the plural. Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.

Claims

CLAIMS1. A wave energy converter (10) for converting in operation energy conveyed in ocean waves propagating in a forward direction (40) in an ocean environment and received at the converter (10) via an energy pickoff arrangement (60) into generated power, the converter (10) includes a plurality of columns (20) which are in fluidic communication via corresponding ports (50) to the ocean waves received at the converter (10), wherein the ports (50) are arranged substantially in series along the forward direction (40), and wherein the pods (50) are of progressively greater depth into the ocean environment along the forward direction (40) so as to cause the ocean waves to propagate in a downwardly-directed vortex (45) when received at the ports (50), characterized in that one or more of the columns (20) have an upwardly tapered cross-section when in operation, and are coupled substantially at their upper ends to the energy pickoff arrangement (60).
2. A wave energy converter (10) as claimed in claim 1, characterized in that the energy pickoff arrangement (60) includes an energy pickoff device (60) for each of the one or more columns (20).
3. A wave energy converter (10) as claimed in claim 1, characterized in that the energy pickoff arrangement (60) includes an energy pickoff device (60) which is shared between a plurality of the columns (20).
4. A wave energy converter (10) as claimed in claim 1, characterized in that the energy pickoff arrangement (60) includes one or more poly-cuspid valves for causing a uni-direction flow of air provided from one or more columns (20) to pass through a turbine (120) for generating power.
5. A wave energy converter (10) as claimed in claim 4, characterized in that the one or more poly-cuspid valves include at least one tricuspid valve.
6. A wave energy converter (10) as claimed in claim 4, characterized in that one or more flaps (180, 190) of the one or more poly-cuspid valves are fabricated from a flexible polymeric plastics material.
7. A wave energy converter (10) as claimed in claim 6, characterized in that the flexible polymeric plastics material includes at least one of: Nitrile rubber, polyurethane, silicone rubber.
8. A wave energy converter (10) as claimed in claim 4, characterized in that the one or more poly-cuspid valves include one or more flexible cords to prevent the one or more flaps (180, 190) from folding further than a mutually abutting arrangement when the valves are in a closed state..
9. A wave energy converter (10) as claimed in claim 4, characterized in that the one or more poly-cuspid valves include at least one pyramidal-type frame to prevent the one or more flaps (180, 190) from folding further than a substantially mutually abutting arrangement when the valves are in a closed state..
10. A wave energy converter (10) as claimed in claim 1, characterized in that the plurality of columns (20) are arranged so that that their elongate axes are substantially aligned along a first direction, and that the ports (50) have corresponding port angles (0) relative to the first direction which are progressively larger as the ports (50) are of progressively greater depth.
11. A wave energy converter (10) as claimed in claim 10, characterized in that the first direction is substantially a vertical direction when the converter (10) is in operation.
12. A wave energy converter (10) as claimed in claim 1, characterized in that the ports (50) have an elliptical, round or rectilinear cross-section.
13. A wave energy converter (10) as claimed in claim 1, characterized in that the plurality of columns (20) are operable to couple to the ocean waves received at the ports (50) in a resonant manner.
14. A wave energy converter (10) as claimed in any one of the preceding claims, characterized in that the converter (10) includes in a range of 2 to 10 columns (20) and associated pods (50) arranged in series.
15. A wave energy converter (10) as claimed in any one of the preceding claims, characterized in that one or more of the columns (20) include one or more additional wave energy absorbing devices therein.
16. A wave energy converter (10) as claimed in claim 13, characterized in that the one or more additional wave energy absorbing devices include at least one piston device.
17. A wave energy system (300) including a platform defining a peripheral edge thereto, characterized in that a plurality of wave energy converters (10) as claimed in any one of the preceding claims are mounted substantially around at least a portion of said peripheral edge to receive ocean waves propagating towards the system at the converters (10).
18. A method of converting energy conveyed in ocean waves propagating in a forward direction in an ocean environment when received at a wave energy converter (10) via an energy pickoff arrangement (60) to generate power, characterized in that said method includes: (a) arranging for a plurality of columns (20) of the converter (10) to be in fluidic communication via corresponding ports (50) to the ocean waves received at the converter (10), wherein one or more of the columns (20) have an upwardly tapered cross-section when in operation, and are coupled substantially at their upper ends to an energy pickoff arrangement (60); (b) arranging for the columns (20) to be disposed substantially in series along the forward direction (40); and -20 - (c) arranging for the ports (50) to be progressively greater depth into the ocean environment along the forward direction (40) so as to cause the ocean waves to propagate in a downwardly-directed vortex (45) when received at the ports (50).
19. A method as claimed in claim 16, characterized in that said method includes arranging the plurality of columns (20) so that that their elongate axes are substantially aligned along a first direction, and that the ports (50) have corresponding port angles (0) relative to the first direction which are progressively larger as the ports (50) are of progressively greater depth.
20. A method as claimed in claim 16, characterized in that the method includes using poly-cuspid valves (100, 140) coupled to the one or more columns (20) for causing a substantially uni-directional air flow through at least one turbine (120) to generate power.
21. A wave energy converter (10) for converting in operation energy conveyed in ocean waves propagating in a forward direction (40) in an ocean environment and received at the converter (10) via an energy pickoff arrangement (60) into generated power, the converter (10) includes a plurality of columns (20) which are in fluidic communication via corresponding ports (50) to the ocean waves received at the converter (10), wherein the ports (50) are arranged substantially in series along the forward direction (40), and wherein the ports (50) are of progressively greater depth into the ocean environment along the forward direction (40) so as to cause the ocean waves to propagate in a downwardly-directed vortex (45) when received at the ports (50), characterized in that the energy pickoff arrangement (60) includes one or more poly-cuspid valves for causing a uni-direction flow of air provided from one or more columns (20) to pass through a turbine (120) for generating power.