WO2013011251A1 - Convertisseur de l'énergie des vagues - Google Patents

Convertisseur de l'énergie des vagues Download PDF

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Publication number
WO2013011251A1
WO2013011251A1 PCT/GB2012/000209 GB2012000209W WO2013011251A1 WO 2013011251 A1 WO2013011251 A1 WO 2013011251A1 GB 2012000209 W GB2012000209 W GB 2012000209W WO 2013011251 A1 WO2013011251 A1 WO 2013011251A1
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WO
WIPO (PCT)
Prior art keywords
wave
energy converter
arm
wave energy
wave field
Prior art date
Application number
PCT/GB2012/000209
Other languages
English (en)
Inventor
Peter Kenneth Stansby
Original Assignee
Mace Wave Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mace Wave Limited filed Critical Mace Wave Limited
Publication of WO2013011251A1 publication Critical patent/WO2013011251A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/14—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy
    • F03B13/16—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem"
    • F03B13/20—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" wherein both members, i.e. wom and rem are movable relative to the sea bed or shore
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2250/00—Geometry
    • F05B2250/40—Movement of component
    • F05B2250/42—Movement of component with two degrees of freedom
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/84—Modelling or simulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Definitions

  • the present invention relates to a wave energy converter, a method of designing a wave energy converter and to a method of using a wave energy converter.
  • renewable energy sources In recent years there has been an increasing drive to identify and use renewable energy sources.
  • One such renewable energy source that has been identified and used is wave power.
  • the basic principle of using this renewable energy source lies in the design of a structure that is in some way able to convert wave energy into another form of energy, for example kinetic energy or electrical energy.
  • Some of such structures are immovable in a wave field in which the structure is used, for example being fixedly located on a sea bed or the like.
  • a disadvantage with this approach is the cost of fixing the structure to the sea bed, particularly in deep water.
  • Another disadvantage is the inability to move the structure easily after initial installation, which may sometimes be required.
  • the structure may be movable across the surface of the water, not necessarily being rigidly fixed in position on or relative to a sea bed or the like.
  • a method of designing a wave energy converter that is configured to float in water, the wave energy converter comprising: a first body, configured to float in water; a second body, configured to float in water; and the first body and the second body being connected to one another via an arm, the arm separating the first body from the second body, substantially in a horizontal direction in use, the arm being pivotally connected to at least one of the first body and second body; the method comprising: designing one or more properties of the wave energy converter such that the wave energy converter is tuned or tuneable for use in a particular wave field, so as to, in use, result in: heave resonance of one or both of the first body and the second body, and/or roll or pitch resonance of one or both of the first body and the second body; and substantially anti-phase motion of the first body and the second body for that wave field.
  • the method may further comprise making a wave energy converter according to the design.
  • the first body may be additionally connected to the second body by an additional arm.
  • the additional arm may have substantially a same length as the arm.
  • the additional arm may have substantially a different length as the arm (e.g. a longer or shorter length).
  • the property may be one or more, or a combination of: a separation between the first body and the second body; and/or a draft, in use, of the first body and/or the second body; and/or a mass of the first body and/or the second body; and/or a dimension of the first body and/or the second body; and/or a centre of buoyancy of the first body and/or the second body; and/or a centre of gravity of the first body and/or the second body; and/or a position of a metacentre of the first body and/or the second body; and/or a second moment of area (e.g. the area in plan view) of the first body and/or the second body.
  • the separation between the first body and the second body may be tuned or tuneable to be substantially between a quarter and three-quarters of a wavelength in the wave field, or substantially equal to a half-wavelength of a wave in the wave field.
  • the first body may be smaller in size and/or weight than the second body.
  • the first body may be attached or attachable to another object to restrict movement of the wave energy converter across the wave field.
  • the first body and/or second body may have a diameter of between 5m and 100m.
  • the lower limit may be determined by the smallest practical size for useful energy generation, and/or the upper limit may be less than about half the wavelength of large waves likely to be experienced and otherwise a practical upper limit.
  • Preferably the first body and/or second body may have a diameter of between 20m and 60m.
  • the lower limit gives significant energy generation, and/or the upper limit is about half the wavelength of smaller swell waves.
  • the mass of the first and/Or second body may be deemed as secondary parameters, the required mass perhaps being dependent on other properties of the wave energy converter (e.g. those required for resonance).
  • first body and/or second body may have a mass of between 40 tonnes and 120,000 tonnes (or higher), preferably between 1000 tonnes and 40,000 tonnes.
  • the first body and/or second body may have a diameter that is substantially equal to or less than half a wavelength of a wave in the wave field.
  • the pivotal connection may comprise: a hinge or pivot in connection with the arm, and a secondary arm in connection with the hinge or pivot, the hinge or pivot being connected to the respective first body or second body; and/or wherein the first body and the second body are each pivotally connected to the arm.
  • the wavelength of a wave in the wave field may be in the range of 40m to 300m (as determined for possible wave periods in the range 5s to 15s), optionally in the range of 40m to 160m (the upper limit being associated with most swell waves).
  • the wave energy converter may comprise, be provided with, or be used in conjunction with, thrusters for use in aligning or attempting to align the converter with a wave train direction.
  • the method may further comprise using the wave energy converter in the wave field, the wave field optionally comprising swell waves.
  • the method may further comprise extracting energy from the wave energy converter using movement of the first body and/or second body about the pivotal connection.
  • a wave energy converter that is configured to float in water
  • the wave energy converter comprising: a first body, configured to float in water; a second body, configured to float in water; and the first body and the second body being connected to one another via an arm, the arm separating the first body from the second body, substantially in a horizontal direction in use, the arm being pivotally connected to at least one of the first body and second body; the method comprising using the wave energy converter in a wave field that results in: heave resonance of one or both of the first body and the second body, and/or roll or pitch resonance of one or both of the first body and the second body; and substantially anti-phase motion of the first body and the second body for that wave field.
  • the method may further comprise making a wave energy converter for such use.
  • a wave energy converter configured to float in water, comprising: a first body, configured to float in water; a second body, configured to float in water; the first body and the second body being connected to one another via an arm, the arm separating the first body from the second body, substantially in a horizontal direction in use, the arm being pivotally connected to at least one of the first body and second body; wherein one or more properties of the wave energy converter are tuneable, to tune the wave energy converter for use in a particular wave field, such that, in use, the tuning results in: heave resonance of one or both of the first body and the second body, and/or roll or pitch resonance of one or both of the first body and the second body; and substantially anti-phase motion of the first body and the second body for that wave field
  • the wave energy converter may be made/designed according to one of the methods described herein.
  • a wave energy converter configured to float in water, comprising: a first body, configured to float in water; a second body, configured to float in water; and the first body and the second body being connected to one another via an arm, the arm separating the first body from the second body, substantially in a horizontal direction in use, the arm being pivotally connected to at least one of the first body and second body; wherein one or more properties of the wave energy converter are tuned for use for use in a particular, pre-determined wave field, such that, in use, the tuning results in: heave resonance of one or both of the first body and the second body, and/or roll or pitch resonance of one or both of the first body and the second body; and substantially antiphase motion of the first body and the second body for that wave field
  • the wave energy converter may be made/designed according to one of the methods described herein.
  • Figure 1 schematically depicts a wave energy converter
  • Figure 2 schematically depicts a wave energy converter according to a first embodiment of the present invention
  • Figure 3 schematically depicts a plan view of the wave energy converter of Figure 2;
  • Figure 4 schematically depicts a wave energy converter according to a second embodiment of the present invention
  • Figure 5 schematically depicts principles associated with the wave energy converter of Figure 4, and/or the design or tuneability thereof; and Figure 6 schematically depicts a wave energy converter according to another embodiment of the present invention.
  • FIG. 1 schematically depicts a wave energy converter.
  • the wave energy converter comprises a first body 6 configured to float in water 4.
  • the wave energy converter also comprises a second body 6, also configured to floating water.
  • the first body 2 and the second body 6 are the same size and weight.
  • the first body 2 and the second body 6 are connected to one another via an arm 8.
  • the arm 8 separates the first body 2 from the second body 6, substantially in a horizontal direction in use (i.e., across a surface of water in or on which the wave converter is used).
  • the first body 2 and the second body 6 are each pivotally connected to the arm 8 via secondary arms 10, 12 and respective pivots 14, 16.
  • the wave energy converter is located on the surface of water 4 that has a wave field (which could alternatively or additionally be described as a set of wave conditions).
  • the wave energy converter of Figure 1 can be used to convert energy of the waves into another form of energy - for example, by converting or extracting energy at the pivots 14, 16.
  • the energy conversion is undertaken in a somewhat arbitrary manner, with no apparent consideration being given to optimising the energy conversion.
  • the present invention is based on such consideration.
  • the present invention may be expressed or defined in one of a number of different ways, in isolation or combination.
  • the present invention may be defined as a method of designing a wave energy converter.
  • the designing may involve designing one or more properties of the wave energy converter such that the wave energy converter is tuned or tuneable for use in a particular wave field, so as to, in use, result in heave resonance of one or both of the first body and the second body, roll or pitch resonance of one or both of the first body and the second body, or substantially anti-phase motion of the first body and the second body for that wave field.
  • the method may optionally comprise making a wave energy converter to that design.
  • the present invention may be defined as a method of using a wave energy converter.
  • This method comprises using a given (e.g. existing) wave energy converter in a wave field that results in heave resonance of one or both of the first body and the second body, roll or pitch resonance of one or both of the first body and the second body, or substantially anti-phase motion of the first body and the second body for that wave field.
  • the invention may alternatively or additionally be defined as a wave energy converter, one or more properties of which are tuneable, to tune the wave energy converter for use in a particular wave field (e.g. so as to, in use, result in heave resonance of one or both of the first body and the second body, roll or pitch resonance of one or both of the first body and the second body, or substantially anti-phase motion of the first body and the second body for that wave field).
  • the invention may alternatively or additionally be defined as a wave energy converter, one or more properties of which having been tuned (i.e., during manufacture, design, installation or the like) for use in the particular, pre-determined wave field (e.g. so as to, in use, result in heave resonance of one or both of the first body and the second body, roll or pitch resonance of one or both of the first body and the second body, or substantially anti-phase motion of the first body and the second body for that wave field).
  • the present invention is subtle and may in some instances appear to be extremely similar to existing wave energy converters or methods of using such converters.
  • the subtlety lies in the designing, using or tuning of a wave energy converter for use in a particular wave field, to optimise the conversion of energy via resonance or anti-phase motion of or between the bodies forming the wave energy converter.
  • the subtlety might alternatively lie in the appreciation that, for a given wave field, use of a particular wave energy converter will result in an increase in energy conversion.
  • FIG. 2 schematically depicts a wave energy converter according to an embodiment of the present invention.
  • the wave energy converter comprises a first body 30, configured to float in water 32.
  • the converter also comprises a second body 34, also configured to float in water 32.
  • the first body 30 and second body 34 are connected to one another via an arm 36.
  • the arm separates the first body 30 from the second body 34, substantially in a horizontal direction in use (e.g. across a surface of the water 32).
  • the arm 36 is pivotally connected to each of the first body 30 and the second body 34 by pivots 38, 40 and respective secondary arms 42, 44 that extend from those pivots 38, 40 and into connection with the first body 30 and second body 34, respectively.
  • a separation 46 between the first body 30 and the second body 34 is equal to half a wavelength 48 of a wave in the wave field. This ensures that, in use, the heave motion of the first body 30 and the second body 34 are in anti-phase, and to the maximum extent possible in that wave field, thus maximising energy conversion obtainable from heave motion.
  • the half wavelength separation is not essential, with useful anti-phase motion being generated when the separation 46 is between a quarter and three-quarters of a wavelength in the wave field.
  • the relationship between the wavelength in the wave field and the separation 46 between the first body 30 and the second body 34 can be achieved in one of a number of ways, as already alluded to above.
  • the separation can be achieved by using an existing wave energy converter in a wave field in which the relationship is satisfied (i.e., matching the wave field to the separation between the first and second bodies).
  • the wavelength of a wave field in which a wave energy converter is to be used or installed will almost certainly be known in advance for reasons of planning permission, expected energy generation, and the like. With this knowledge, the separation between the first and second bodies 30, 34 can be designed to satisfy the above relationship.
  • the separation between the first and second bodies 30, 34 could be tuneable, for example by being able to change the length of arm 36, or in any one of a number of different ways (e.g. changing the pivot position along the arm 36).
  • Figure 3 is used to show the wave energy converter in plan view. Consecutive crests and troughs of waves are indicated by lines 50.
  • the first body 30 and the second body 34 are separated by a distance equal to a distance between a trough and a crest of a wave - i.e., half a wavelength.
  • This relationship may also lead to the establishment or maintenance of standing waves (or at least partially standing waves) created by reflection of waves off one of the first or second body 30, 34 towards one of the other of the first or second body 30, 34.
  • standing waves may also lead to optimised or increased energy conversion.
  • first body 30 is smaller in size and/or weight than the second body 34.
  • wave energy converter may always self-align with a direction of a wave train 52, which may further optimise energy extraction.
  • first body 30 is attachable to another object to restrict movement of the wave energy converter as a whole across the wave field. For instance, the first body 30 may be attached to the sea bed 54 via appropriate tethers, mooring lines or anchors, or the like 56.
  • the wave energy converter may be attached (which includes tethered or the like) to a floating installation such as an oil rig or a buoy or the like.
  • a floating installation such as an oil rig or a buoy or the like.
  • the first body and/or second body 30, 34 may have a diameter of between 5m and 100m.
  • the lower limit may be determined by the smallest practical size for useful energy generation, and/or the upper limit may be less than about half the wavelength of large waves likely to be experienced and otherwise a practical upper limit.
  • Preferably the first body and/or second body may have a diameter of between 20m and 60m.
  • the lower limit gives significant energy generation, and/or the upper limit is about half the wavelength of smaller swell waves.
  • the mass of the first and/or second body 30, 34 may be deemed as secondary parameters, the required mass perhaps being dependent on other properties of the wave energy converter (e.g. those required for resonance).
  • the first body and/or second body may have a mass of between 40 tonnes and 120,000 tonnes (or higher), preferably 1000 tonnes and 40,000 tonnes.
  • the first body might have a diameter of around 20m.
  • the mass might exceed 100 tonnes, or 1 ,000 tonnes.
  • the first body might have a diameter of around 40m.
  • the mass might exceed 100 tonnes, or 1 ,000 tonnes, or 5,000 tonnes.
  • the first and second bodies might have one of a number of different shapes. Cylindrical shapes might be preferred due to relatively simplicity of construction and installation, and/or due to the curved surface that would be presented to incoming waves (which might promote advantageous diffraction of such waves, or limit dissipation). Other shapes may of course be used, for example bodies having a square or rectangular cross section. Such square or rectangular shapes may be easier to construct than cylindrical bodies, and/or have other desirable properties, such as promoting advantageous diffraction and/or reflection of waves. The larger body might generate waves that cause motion of the first body.
  • the first and second bodies may be formed from multiple sub-bodies. One or more additional bodies may be attached to one of the pivots to allow for further energy extraction.
  • the multiple bodies may for form a chain of bodies, or be connected to a central pivot or the like.
  • the bodies need not be custom built.
  • the bodies could be barges or buoys or the like.
  • the wave energy converter will, of course, need to be located in a wave field.
  • That wave field may preferably comprise swell waves.
  • Swell waves are consistent and predictable in both terms of timing, frequency, magnitude and the like.
  • the use of swell waves also allows energy conversion to be optimised, both in terms of being able to design or tune a wave energy converter for a predictable wave field, and also because the wave energy conversion itself will be consistent (since the swell waves themselves are consistent). This avoids or limits the problem of intermittent energy conversion that has long been associated with some forms of wave power, and wind power.
  • the waves in the wave field will typically have a wavelength in the range of 40m to 300m (as determined for possible wave periods in the range 5s to 15s), optionally in the range of 40m to 160m (the upper limit being associated with most swell waves).
  • Power take-off from the wave energy converter is not the subject of the present invention.
  • power take off could be undertaken via one or both of the pivots, for example using a rack and pinion arrangement with a clutch and gearbox, or a series of gears and clutches.
  • a flywheel could smooth the power output.
  • Another possibility would be to use motion of the bodies (e.g. via the pivots) to drive a pump or pumps with the resulting flow of water driving a turbine, e.g. a Pelton wheel.
  • the present converter is expected to generate high torque and relatively low motion, and this would in turn be suitable for generating fluid flow under very high pressure, well suited to Pelton turbines.
  • power takeoff via a hydraulic system is thought to be most likely.
  • Power take-off may be achieved during each cycle, or during each half cycle. A preference may depend on the type of mechanism used in the power-take off. Power-take off may be advantageously undertaken during downwards heave (e.g. of the larger of the two bodies, or of both bodies), so that the arms or other supports are, at least in general, under tension. While the wave energy converter might preferably be used to provide electricity, the converter might additionally or alternatively be used to provide power for desalination or for hydrogen generation.
  • Promoting or ensuring anti-phase motion between the two bodies of the wave energy converter is not the only way of achieving optimum or increased energy conversion. Resonant motion can also be taken advantage of, as will now be described in relation to Figure 4.
  • Figure 4 schematically depicts another embodiment of the present invention, which may be used independently of or (preferably, to increase energy conversion) in combination with the embodiment of Figures 2 and 3.
  • a separation between the first body 30 and second body 34 has again been designed to be substantially equal to half a wavelength of a wave in the wave field, thus ensuring or encouraging (e.g. maximum) anti-phase motion between the first body and the second body in use.
  • resonant motion has been encouraged or ensured, further optimising energy conversion.
  • the subtle but important concept of resonance combined with anti-phase motion has not been realised in wave energy converters of this type (i.e., of this general structure).
  • the resonance may be heave resonance 60 of one or both of the first body 30 or second body 34, or roll or pitch resonance 62 of one or both of the first body 30 or second body 34.
  • resonance criteria can be established by designing the wave energy converter with prior knowledge of the wave field in which the wave energy converter is to be used.
  • resonance can be achieved by using a particular wave energy converter in a wave field that will generate resonant motion of the wave energy converter.
  • the wave energy converter properties can be fixed or, conversely, they may be tuneable to achieve resonance - for example, varying one or more properties of the wave energy converter to achieve resonance. The concept and use of resonance will now be discussed in more detail.
  • resonance is considered for a substantially cylindrical body, the circular surfaces of which are substantially parallel to the surface of the water in which the converter is used (i.e. a longitudinal axis of the converter extends substantially perpendicularly with respect to, and through, the surface of the water).
  • Heave resonance is where vertical motion causes variable buoyancy balanced by inertia and damping forces.
  • the mass of a body is equal to the displaced mass of water (in stationary conditions).
  • T h 10s
  • C a 1 (which is typical)
  • heave period T h is dependent on draft and added mass coefficient, the added mass coefficient being dependent on draft/radius ratio.
  • draft is the dominant parameter.
  • Draft d (and thus heave period T ) can be changed/tuned, for example by pumping water in to or out of the body, for example to tune for certain wave fields.
  • metacentric height B.M is dependent on r and d. Draft d (and thus metacentric height B.M) can be changed/tuned, for example by pumping water in to or out of the body, for example to tune for or take into account certain wave fields.
  • Roll resonance is where rotational motion causes variable buoyancy balanced by inertia and damping forces.
  • IG is the moment of inertia of the body about a horizontal line through its centre of gravity
  • C r is coefficient of added mass for roll
  • m mass of body (equal to displaced mass of water)
  • position of metacentre is position of metacentre
  • G centre of gravity. It may be desirable for the pivot point to be close to centre of gravity.
  • the centre of gravity is the natural roll centre and having the pivot point coincident might lead to improvements in efficiency, stability or simply operation of the converter in general.
  • T r ⁇ (r 2 (1+C r )/(g. .G) ⁇ and as a result depends on radius r for a given M.G.
  • Heave resonance period may be specified for one or two bodies. Note this period is dependent mainly on draft, and draft may be tuned by pumping water into or out of a body as ballast for a particular wave field, known say 6-12 hours in advance.
  • Metacentric height should be determined, dependent on draft and radius.
  • Roll natural period is otherwise dependent mainly on radius. Radius should thus be set to give roll natural period corresponding to predominant wave period. This, for example, could well be the predominant swell period. Roll energy will probably be most significant on a large body.
  • resonance may depend on one or more of a number of different properties of the wave energy converter. These properties may be designed for resonance, tuned or tuneable for resonance, or be of a magnitude or the like that coincides with resonant conditions for a particular wave field.
  • Figure 5 shows the wave energy converter of Figure 4, but with exemplary indications of properties that may be varied to ensure, encourage or promote resonance (or the anti-phase motion described previously). These properties may coincide with (for example, being the same magnitude, but achieved in a different manner), or be the same as, the properties discussed previously in the examples given for achieving heave and roll resonance.
  • the properties might be other properties, however, which also (or alternatively) have an affect on resonance (for example, if the bodies were different shapes - e.g.
  • a property may be one or more of, or a combination of, a separation 48 between the first body 30 and the second body 34; and/or a draft 68, in use, of the first body 30 and/or the second body 34; and/or a mass 70 of the first body 30 and/or the second body 34(the mass or draft being changeable, for example, by pumping water in to or out of the first body 30 or second body 34); and/or a dimension (e.g., diameter 72 or height 74 or shape) of the first body and/or the second body; and/or a centre of buoyancy of the first body 30 and/or the second body 34; and/or a centre of gravity of the first body 30 and/or the second body 34; and/or a position of a metacentre of the first body 30 and/or the second body 34; and/or a second moment of area of the first body 30 and/or of the second body 34.
  • a dimension e.g., diameter 72 or height 74 or shape
  • Other properties may, for example, be a distance between a pivot 38 and a base 76 of a body, or between the pivot and the top 78 of a body, or between the top of the body and the waterline 80.
  • the properties described may be interrelated with one another, or may be given different names in different contexts, while still having the same effect/functional property.
  • the heave and roll/pitch motions are additive effects in generating rotary motion at each or the pivot point due to the nature of progressive waves.
  • Increasing the anti-phase motion, and/or inducing resonance adds to this additive effect.
  • the use of two bodies that are in connection with one another increases the energy that can be derived from the device in comparison with, for example, a single body device. This is because a greater degree of relative motion can be achieved with two or more bodies than with a single body.
  • energy conversion may be increased or optimised by the use of a lever mechanism.
  • Figure 6 shows a wave energy converter as shown in and described with reference to any one of Figures 2 to 5, but with a lever structure.
  • the lever structure comprises an additional arm 80 and pivots 82, 84 located at each end of the additional arm 80.
  • the additional arm 80 and pivots 82, 84 are connected to the previously described pivots 38, 40 by way of tertiary arms 86, 88.
  • the tertiary arms 86, 88 are a continuous extension of secondary arms 42, 44 (in another embodiment, the tertiary arms may be fixedly attached to the secondary arms). This may provide more effective power extraction, since the movement of the arrangement as a whole (or bodies thereof) may be constrained in such a way to, for example, improve or encourage resonance.
  • the tertiary arms 86, 88 extend in a direction parallel to the direction of extension of the secondary arms 42, 44. In another example (not shown), the tertiary arms 86, 88 can extend in a direction that is not parallel to the direction of extension of the secondary arms 42, 44, e.g. away from the arm 80, or toward the arm 80, which may have an advantageous affect on power-take off, stability of the arrangement as a whole, or some other advantage.
  • the additional arm 80 is longer than the (primary) arm 36, to introduce a lever effect. Such a lever mechanism may be used to increase the motion of one or more of the first body 30 or second body 34, increasing or maximising energy conversion (e.g. and thus power take-off).
  • the additional arm need not be greater in length than the primary arm.
  • the additional arm could be the same length as the primary arm.
  • an additional arm may not be expected to increase or optimise energy conversion. However, and surprisingly, this is not the case - in experiments, an additional arm has indeed been found to increase or optimise energy conversion. In one experiment, for example, the presence of the additional arm resulted in a four times increase in energy conversion. Although the reasons for this are not yet fully understood, one theory is that the additional arm has an affect on the movement of the first and/or second body, for example by imposing movement constraints or the like in one or more directions. This is thought to result in an encouragement and/or an increase in heave and/or pitch resonance, increasing energy conversion and power take- off.
  • the first body may be smaller in size and/or weight than the second body.
  • An advantage of this feature was described as being that the wave energy converter will always self-align with a direction of a wave train, which may further optimise energy extraction.
  • there may also be a current which current may not be in alignment with the wave train and which may thus act on the wave energy converter to move the converter out of alignment with the wave train. This might reduce energy conversion efficiency.
  • the wave energy converter may comprise, be provided with, or be used in conjunction with, thrusters for use in aligning or attempting to align the converter with the wave train direction.
  • the thrusters may be any convenient type of thrusters, for example using jets, fans, propellers, impellers, turbines or the like to generate a required thrust.
  • the thrusters may be powered with power generated by the converter.
  • the use of thrusters is another feature of the converter which allows the converter to be tuned to the wave field.
  • Roll resonance has been discussed above, although this could be described alternatively or additionally as pitch resonance. For instance, for cylindrical bodies pitch and roll are equivalent. For bodies of a different shape, roll and pitch resonance may be different, and separately attainable (either in isolation or in combination).
  • the different embodiments described above may, when and where appropriate, be used in isolation or in combination with one another.
  • the anti-phase relationship discussed above is most preferably used in combination with the resonance criteria discussed above to maximise power take-off.
  • Other features of the invention for example the attaching of the first body to another object, or the first body being smaller than the second object, may also be used in combination with one, more or all of the embodiments described above.
  • the embodiments described above have been given by way of example only. Various modifications may be made to the described embodiments, and also to embodiments not described herein, without departing from the scope of the invention, which is defined by the claims that follow.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)

Abstract

Selon un aspect, la présente invention concerne un procédé de conception d'un convertisseur de l'énergie des vagues qui est conçu pour flotter dans l'eau, le convertisseur de l'énergie des vagues comprenant : un premier corps conçu pour flotter dans l'eau ; un second corps conçu pour flotter dans l'eau ; et le premier corps et le second corps étant reliés l'un à l'autre par l'intermédiaire d'un bras, le bras espaçant le premier corps du second corps, sensiblement dans une direction horizontale en utilisation, le bras étant relié de façon pivotante à au moins l'un du premier corps et du second corps ; le procédé consistant à : calculer une ou plusieurs propriétés du convertisseur de l'énergie des vagues de telle sorte que le convertisseur de l'énergie des vagues est accordé ou peut être accordé pour être utilisé dans une gamme particulière de vagues, de telle sorte qu'en utilisation, il a pour résultat une résonance de pilonnement de l'un ou de chacun du premier corps et du second corps, une résonance de roulis ou de tangage de l'un ou de chacun du premier corps et du second corps ou un mouvement sensiblement en opposition de phase du premier corps et du second corps pour cette gamme de vagues. D'autres aspects correspondants sont décrits et définis.
PCT/GB2012/000209 2011-07-20 2012-03-02 Convertisseur de l'énergie des vagues WO2013011251A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB1112468.2A GB201112468D0 (en) 2011-07-20 2011-07-20 Wave energy converter
GB1112468.2 2011-07-20

Publications (1)

Publication Number Publication Date
WO2013011251A1 true WO2013011251A1 (fr) 2013-01-24

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GB (1) GB201112468D0 (fr)
WO (1) WO2013011251A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2073824A (en) * 1980-04-14 1981-10-21 Univ Osaka Wave energy converter
US4392349A (en) * 1980-07-21 1983-07-12 Hagen Glenn E Spaced apart wave generator float array
US4781023A (en) * 1987-11-30 1988-11-01 Sea Energy Corporation Wave driven power generation system
US20090160191A1 (en) * 2005-11-07 2009-06-25 Beane Glenn L System for producing energy through the action of waves

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2073824A (en) * 1980-04-14 1981-10-21 Univ Osaka Wave energy converter
US4392349A (en) * 1980-07-21 1983-07-12 Hagen Glenn E Spaced apart wave generator float array
US4781023A (en) * 1987-11-30 1988-11-01 Sea Energy Corporation Wave driven power generation system
US20090160191A1 (en) * 2005-11-07 2009-06-25 Beane Glenn L System for producing energy through the action of waves

Also Published As

Publication number Publication date
GB201112468D0 (en) 2011-08-31

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