GB2576908A

GB2576908A - A wave power electric generator

Info

Publication number: GB2576908A
Application number: GB1814513.6A
Authority: GB
Inventors: Hunter Cairns Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-06
Filing date: 2018-09-06
Publication date: 2020-03-11
Anticipated expiration: 2038-09-06
Also published as: GB201814513D0; GB2576908B

Abstract

A wave power electric generator comprises one or more buoyant units 110, each containing a solenoid coil 140, a magnet 130 and a rail 120 which tilts with the buoyant unit. Either the solenoid coil 140 or the magnet 130 is displaceable under gravity along the rail to cause relative displacement to generate electricity. Two units 110 may be pivoted together by hinges 160 which may be made from non-ferrous material. The units may be surrounded by an impervious jacket 112 which includes a sleeve portion 162 which encloses the hinges 160. The unit(s) may be anchored by a variable length e.g. sprung anchoring cable 170, which may include an electric connection between the unit and an anchoring point.

Description

(71) Applicant(s):

Andrew Hunter Cairns

Cramond Vale, Edinburgh, Scotland, EH4 6RB, United Kingdom (72) Inventor(s):

Andrew Hunter Cairns (56) Documents Cited:

CN 206801767 U

CN 106523257 A

CN 101818717 A

US 4110630 A

CN 107514331 A

CN 102361417 A

DE 102009047232 A1

US 20180230961 A1 (58) Field of Search:

INT CL F03B

Other: EPODOC, WPI, Patent Fulltext (74) Agent and/or Address for Service:

ipconsult

21A Commercial Road, SWANAGE, Dorset, BH19 1DF, United Kingdom (54) Title of the Invention: A wave power electric generator Abstract Title: Wave power system with linear generator (57) A wave power electric generator comprises one or more buoyant units 110, each containing a solenoid coil 140, a magnet 130 and a rail 120 which tilts with the buoyant unit. Either the solenoid coil 140 or the magnet 130 is displaceable under gravity along the rail to cause relative displacement to generate electricity. Two units 110 may be pivoted together by hinges 160 which may be made from non-ferrous material. The units may be surrounded by an impervious jacket 112 which includes a sleeve portion 162 which encloses the hinges 160. The unit(s) may be anchored by a variable length e.g. sprung anchoring cable 170, which may include an electric connection between the unit and an anchoring point.

100

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

11 19

2/4

Hr

11 19

FIG. 2

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11 19

FIG. 3

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FIG. 4

A Wave Power Electric Generator

Field of the Invention

The present invention relates to a wave power electric generator, more specifically the invention relates to a wave power electric generator which generates electricity as it is tilted on the surface of the waves.

Background to the Invention

Wave power electrical generator designs include point absorber buoys which use buoys on the surface to drive generators on the seabed, surface attenuators which use a flexing motion to drive hydraulic pumps, and oscillating wave surge converters which comprise bodies oscillating with respect to a fixed point.

Many wave power generators are restricted in where they can be located, and in particular may not be suitable for rugged coastline locations, for example due to accessibility and depth of installation factors.

An aim of the present invention is to provide an improved wave power electrical generator that is suitable for plural locations.

Summary of the Invention

According to a first aspect of the present invention there is provided a wave power electric generator comprising one or more buoyant units, each of the one or more buoyant units containing: a solenoid coil; a magnet; and a rail which tilts with the buoyant unit and along which either the solenoid coil or the magnet is displaceable under gravity such that the solenoid coil and the magnet are displaced with respect to each other.

Electric generators operate by varying the magnetic flux through a surface bounded by a closed circuit, such that a current is induced within the closed circuit. In some generators this is achieved by displacing one or more loops of wire with respect to a magnetic field.

The wave power electric generator of the present invention comprises one or more buoyant units, each comprising a solenoid coil which is displaceable with respect to a magnet under gravity as the unit is tilted. As such the magnetic field through a solenoid coil may be varied by tilting the unit comprising it, causing either the magnet or the solenoid coil to be displaced along the rail, thereby displacing the solenoid coil with respect to the field of the magnet and inducing a current in the coil.

In use the one or more buoyant units of the electric generator may float upon the surface of a body of water (such as a sea, lake, harbour, lake, inlet, river etc.) and may tilt as the surface is disturbed (for example, by waves) such that a current is induced in the one or more solenoid coils. Such a buoyant unit may be tethered in use by one or more anchoring cables extending to anchoring points on the bed or shore of the body of water.

As each unit is tilted, the rail within each unit will also be tilted and if the rail is tilted from or past a horizontal inclination the solenoid coil or magnet which is displaceable along the rail under gravity may be displaced from its original location to the new lowermost end of the rail. This will cause the solenoid coil to be displaced with respect to the magnet and the magnetic field thereof such that a current will be induced within the coil.

Typically, the unit may be tilted from a horizontal inclination by at least seven degrees to displace the solenoid coil or magnet which is displaceable along the rail under gravity, from its original location to the new lowermost end of the rail.

As the solenoid coil or the magnet is displaced forward or backward along the rail an alternating current will be induced in the solenoid coil such that the buoyant unit operates as a linear alternator.

In some embodiments, the generator may comprise a plurality of buoyant units. One, some, or all of the plurality of buoyant units may be rotatable, reorientable, or tilt-able with respect to one, some, or all of the other buoyant units. This may allow the rails of different buoyant units to be tilted independently of each other. For example, the generator may comprise a pair of buoyant units each of which is rotatable with respect to the other.

Some or all of the plurality of buoyant units may be interconnected and/or separated by joints (such as hinges, cylindrical joints, revolute joints, or ball joints) or other interconnecting means which permit relative rotation of the interconnected and/or separated units (such as chains, or other flexible ligatures, which are preferably formed from non-ferrous material).

In some embodiments, the plurality of buoyant units may be interconnected and/or separated by hinges. For example, the generator may comprise a pair of units connected by one or more hinges which may be between a first end of a first of the units and a first end of the second of the pair of units.

The hinges, other joints, or other interconnecting means may connect to or be formed integrally with ends of the buoyant units (which may be elongate buoyant units) that they interconnect and/or separate. This may allow the lengths of the interconnected and/or separated buoyant units to tilt with respect to each other.

In some embodiments the generator may comprise a plurality of buoyant units which are connected end to end, preferably such that they are rotatable, reorientable or tiltable with respect to each other. For example, the generator may comprise a pair of elongate buoyant units connected by a joint between a first end of the one unit and a first end of the other unit such that the two units are rotatable with respect to each other. In another example, the generator may comprise a chain of two or more elongate buoyant units connected end to end by joints or other interconnecting means allowing adjacent units to rotate with respect to each other.

The hinges, other rotating joints, and/or other interconnecting means which interconnect some or all of the plurality of buoyant units are preferably non-ferrous. This may advantageously prevent the hinges or other joints from interfering with the magnet(s) in use. For example, in embodiments where the magnet is displaceable along the rail, a non-ferrous joint would not attract the magnet to a specific point or end of the unit, thereby potentially biasing it away from its intended movement.

In some embodiments, the hinges or other joints between the plurality of elongate buoyant units are locked or lockable against rotation at low wave amplitudes and/or at high wave amplitudes.

In some embodiments the hinges, other joints of other means for interconnecting and/or separating the buoyant units may be enclosed within a cover or casing. For example, they may be encased within a flexible impermeable sleeve extending between the buoyant units which they interconnect and/or separate so as to protect them from the water in which the generator is floating in use. In some embodiments, such a cover or casing may be a portion of a flexible cover or casing which encloses the entire generator (or the buoyant portion thereof), for example, a portion of a flexible jacket containing the plurality of buoyant units and their interconnecting joints or other means.

The magnets comprised by one, some, or all of the buoyant units may be permanent magnets. Alternatively, or additionally, the magnets comprised by one, some, or all of the buoyant units may be electromagnets which may be turned off when the generator is not in use (for example in very calm weather where the buoyant units are not being tilted).

In some embodiments, each unit may comprise a plurality of magnets which may be displaceable along the rail (or a plurality of rails) of the unit or which may be stationary with respect to the rail such that they are displaceable with respect to the solenoid coil of the unit which is displaceable along the rail under gravity. For example, a unit may comprise a plurality of magnets which are stationary with respect to the rail and are distributed along the length of the rail.

Each buoyant enclosure comprises a rail along which one of its magnet and its solenoid coil is displaceable under gravity. The rail preferably extends through or past the other of the magnet and the solenoid such that the solenoid coil experiences a greater change in magnetic field as the magnet or the solenoid coil is displaceable along the rail.

The rail may be supported on the buoyant unit by which it is comprised or may be located within the buoyant unit’s interior. For example, the rail may be located within an enclosed cavity (such as a watertight or impermeable cavity) of the unit such that it is protected from the water on which the buoyant unit floats in use.

The rail may be generally, substantially or entirely straight. In such embodiments the rail may define a linear path for the solenoid coil or the magnet to be displaced along. This may advantageously ensure that the solenoid coil or the magnet is always displaced to the lowermost end of the rail when it is tilted past or from a horizontal orientation rather than becoming trapped at local low-point or minimum on a curved or bent rail.

The rails comprised by one, some, or all of the one or more buoyant units may extend part, most or substantially all of the way along axes extending between opposite ends of the buoyant units (one or both of which ends may be where a joint or other means interconnecting multiple buoyant units is located). One, some, or all of the rails are preferably arranged such that they lie substantially horizontally when the buoyant units by which they are comprised are floating in still water.

In some embodiments one, some, or all of the one or more buoyant units may be elongate, and their rails may extend generally or substantially parallel to their lengths. In some such embodiments, the rails of one, some, or all of the buoyant units may extend along the lengthwise central axis of their buoyant units, such as along the central lengthwise axis of a generally or substantially cylindrical buoyant unit. This may advantageously ensure the rail remains in a generally constant location independent of the buoyant unit rotating around its central lengthwise axis.

In some embodiments, in one, some or all of the one or more buoyant enclosures, the magnet is displaceable along the rail under gravity when the unit and the rail are tilted. In such embodiments the solenoid coil is preferably held stationary with respect to the rail, this will cause the magnetic field at the solenoid coil to vary as the magnet is displaced along the rail.

In such embodiments, the rail may extend lengthwise through the interior of the solenoid coil such that the coil winds around the rail. The magnet is preferably displaceable lengthwise through the interior of the solenoid coil as it is displaced along the rail. For example, the solenoid coil may be generally cylindrical and may comprise a central cylindrical cavity through which the rail extends lengthwise, the cavity being larger than the rail such that magnet is able to fit through the cavity as it slides along the rail under gravity.

In alternative embodiments, in one, some or all of the one or more buoyant enclosures, the solenoid coil is displaceable along the rail under gravity when the unit and rail are tilted. In such embodiments the magnet is preferably held stationary with respect to the rail, this will ensure that as the solenoid coil is displaced along the rail it is displaced through a magnetic field which is stationary with respect to the rail.

In some embodiments, one, some, or all of the one or more buoyant units may comprise a rail which is a cylindrical or profiled tracked which engages with correspondingly profiled passage, slot, groove or notches in the magnet, solenoid coil or a supporting structure thereof. The solenoid coil or magnet may fit onto or around the rail. The solenoid coil or the magnet of a buoyant unit may slide freely along the unit’s rail under gravity in use.

In some embodiments, the rails comprised by one, some or all of the buoyant units may be screwed or threaded such that the magnet or solenoid coil which is displaceable along the rail rotates as it is displaced.

In some embodiments the rail may be arranged to rotate the magnet or solenoid coil as it is displaced along the rail in a single direction but not in the other. For example, the rail may be similar to the shaft of a push screwdriver or spiral ratchet screwdriver and may engage with the magnet of solenoid coil in the same manner as the shaft of a push screwdriver or spiral ratchet engages with its handle.

Buffer stops may be arranged at one or both ends of one, some, or all of the rails comprised by the one or more buoyant units of the electrical generator. These buffer stops may be formed from rubber or from some other resiliently deformable material and may cushion impacts of the magnet or solenoid coil as it slides to an end of the rail when the buoyant unit is tilted.

In some embodiments one, some, or all of the buoyant units may comprise a plurality of rails along which one of the solenoid coils and the magnet is displaceable; these rails are preferably parallel to each other and may have any suitable optional feature described above. For example, one, some, or all of the buoyant units may comprise a pair of parallel rails defining a track along which ether a solenoid coil or the magnet is displaceable in use.

One, some, or all of the one or more buoyant units may comprise one or more interior cavities or chambers. The cavities or chambers are preferably sealed and watertight and may be air-filled or evacuated so as to provide buoyancy.

One, some, or all of the one or more buoyant units may comprise a waterproof casing and/or a waterproof jacket or cover. The casing and/or jacket or cover may enclose the remainder of the buoyant unit and/or any housings, cavities or chambers thereof. In some embodiments the generator may comprise a jacket or cover which encloses two, some or all of the one or more buoyant units, and/or hinges, joints or other means which interconnect and/or separate the buoyant units. Such a jacket of cover may be flexible so as to allow the buoyant units to tilt with respect to each other.

One of the one or more cavities or chambers of a buoyant unit may contain the rail, solenoid coil and magnet of the buoyant unit. The rail may extend across the cavity or chamber (for example parallel to the length of the buoyant unit and/or between buffer stops on opposite walls of the cavity or chamber), one of the solenoid coil and the magnet may be mounted on the rail such that it is displaceable along its length within the cavity or chamber and the other of the solenoid coil and the magnet may be arranged within the chamber or cavity such that the rail extends through or past it.

For example, one, some or all of the buoyant units may comprise a chamber or cavity across which the rail of the buoyant unit extends (preferably parallel to the length of the buoyant unit and between buffer stops on opposite end walls of the cavity or chamber). The magnet of the buoyant unit may be mounted on the rail and may freely slide along its length under gravity. The solenoid coil of the buoyant unit may be arranged such that it surrounds a portion of the rail with sufficient space between itself and the rail for the magnet to slide lengthwise through the coil.

Alternatively, the solenoid coil of the buoyant unit may be mounted on the rail and may freely slide along its length under gravity. The magnet of the buoyant unit may be an electromagnet with a coil arranged such that it surrounds a portion of the rail with sufficient space between itself and the rail for the solenoid coil in which the current is to be induced to slide lengthwise through the electromagnet coil.

The chamber which contains the rail, magnet and solenoid coil may contain additional components, such as buffer stops, monitoring equipment and/or other electrical components (such as a rectifier, transformer or other component which may be used to obtain a desired output current from the currents induced in the solenoid coil).

Alternatively, or additionally, monitoring equipment and/or other electrical components or circuitry (such as those for deriving a desired output current from the currents induced in the solenoid coil) may be located in one or more separate chambers or cavities within the buoyant unit.

In some embodiments, one, some or all of the buoyant units (and/or the cavities or chambers comprised thereby) may be generally or substantially cylindrical. This may allow them to operate in the same manner despite rotating around their central axes.

In some embodiments the generator may be connected to by one or more anchor cables to one or more anchoring points. The anchor cables may extend from floating portions of the generator (such as the buoyant units and joints or other means which interconnect the floating portions) to anchorage points remote therefrom.

One, some or all of the anchorage points may be on the sea bed, lake bed, or river bed etc. Alternatively, or additionally, one some or all of the anchorage points may be on the shore. For example, in some embodiments, one or both ends of the generator may be connected to an anchoring cable for extending to an anchoring point on the shore of the body of water on which the generator floats. In other embodiments, an anchoring cable may extend from each end of the generator to a different anchoring point (such as on the bed of the body of water).

In some embodiments, the anchoring cables and/or the anchoring points may be comprised by the generator.

For example, the generator may comprise first and second elongate buoyant units each with first and second ends. The second end of the first buoyant unit may be connected to first end of the second buoyant unit by one or more joints such as hinges such that the first and second joints are rotatable with respect to each other. The first end of the first buoyant unit may be connected to a first anchor cable and the second end of the second buoyant unit may be connected to a second anchor cable so that both ends of the generator are each connected to a separate anchor cable allowing the position and orientation of the generator to be limited.

In some embodiments, the anchor cable may be sprung, spring loaded, coiled (for example helically coiled). Alternatively, or additionally, the cable may be mounted on an auto rewind reel at the generator of the anchoring point, and/or may be otherwise extendable in length. This may allow the generator a greater degree of movement with respect to the anchoring points so as to accommodate for different conditions such as tides or adverse weather.

In some embodiments, one, some or all of the anchor cables may be electricity carrying cables. One, some or all of such cables may transmit a current generated by the generator (for example, to the shore, or to an additional current carrying cable extending from an anchorage point on the bed of a body of water). Alternatively, or additionally, one, some or all of such cables may carry control or other electronic signals to and/or from the generator.

In some embodiments, one, some or all of the one or more buoyant units may comprise sensing means for detecting the level to which the buoyant unit is tilting, the wave amplitudes or inclination, or other indications of weather conditions. Alternatively, or additionally, the generator may comprise a means for receiving external control signals (for example, an antenna for receiving wireless control signals or a means for receiving control signals via an anchor cable as described above).

In response to a detection by a sensor and/or to a control signal the generator may be operable to, or may automatically, lock or limit the hinge or other joint against rotation, may lock or limit the solenoid coil or the magnet of one, some or all of the buoyant units, and/or may deactivate or adjust electromagnets comprised by the buoyant units.

Preferred embodiments of the invention will now be described, by way of example, with reference to the figures.

Brief Description of the Figures

Figure 1 is a cross sectional view of a wave power electric generator floating on a body of water;

Figure 2 is a cross sectional view of the wave power electric generator with a wave reaching one end thereof;

Figure 3 is a cross sectional view of the wave power electric generator as the wave reaches its centre; and

Figure 4 is a cross sectional view of the wave power electric generator as the wave continues past it.

Detailed Description of the Figures

Referring to the Figures generally there is shown a wave power electrical generator 100 comprising two buoyant generating units 110 which generate electricity as they are tilted by waves 255.

The generator 100 comprises two buoyant units 110 interconnected by hinges 160 and enclosed within a waterproof jacket 112. Each of the buoyant generating units 110 comprises a casing 118, a main cavity 114, and an electrical housing 116 as well as a rail 120, a magnet 130 and a solenoid coil 140 which are located within the main cavity 114. The generator 100 floats on the surface 250 of a body of water and is connected to two anchorage points 180 on the bed 200 of the body of water by a pair of anchoring cables 170.

The first and second buoyant units 110 are generally cylindrical bodies, each with a single hemi-spherical end. The buoyant units comprise a non-ferrous metal waterproof casing 118 which encloses an elongate main cavity 114 and an electrical housing 116. The two ends of the buoyant units 110 which are distal from their hemi-spherical ends are interconnected and separated by non-ferrous hinges 160.

The electrical housings 116 of the two buoyant units 110 are located at their hemispherical ends and extend approximately one quarter of the way along the length of the units 110 towards their interconnected ends. The main cavities 114 of the two buoyant units are cylindrical and extend between the electrical housings 116 and the interconnected non-hemi-spherical ends of the units 110, along approximately three quarters of the length of the buoyant units 110. Both the electrical housing 116 and the main cavity 114 of each buoyant unit is surrounded by the buoyant unit’s external casing 112 which is waterproof and impermeable so as to protect the unit’s contents and to maintain its buoyancy.

The main cavities 114 of the two buoyant units 110 are air-filled so as to provide buoyancy to the units 110, allowing them to float at the surface 250 of the body of water.

Each buoyant unit’s main cavity 114 contains a rail 120 which extends along the central axis of the cylindrical main cavity 114 from a first end wall adjacent the electrical housing 116 and second end wall adjacent the buoyant unit’s non-hemi-spherical hinge interconnected end. As such each of the rails 120 will tilt with buoyant unit 110 within the main cavity 114 within which it is located

A buffer stop 122 is located at each end of each rail 120 to cushion the impact between an object sliding along the rail 120 and the end wall of the main cavity 114.

In the illustrated generator 100, a magnet 130 is mounted on each of the rails 120 and a solenoid coil 140 is located at the midpoint of the length of each of the main cavities

140. The magnets 130 are free to slide lengthwise along the rails 120 under gravity as the rails 120 are tilted and the solenoid coil 140 surrounds the rail 120 and the path along which the magnet 130 is displaceable such that when the rail 120 is tilted past the horizontal, the magnet 120 will slide through the central cylindrical empty core of the solenoid coil 140, thereby significantly changing the magnetic flux though the windings of the solenoid coil 140.

In the illustrated embodiment the magnet 120 is a permanent magnet. In alternative embodiments the magnet 120 may be an electromagnet and/or may comprise a plurality of permanent and/or electromagnets which may be supported on a mounting which slides freely along the rail.

In alternative unillustrated embodiments, a solenoid coil may be mounted on the rail 120 of one or both of the buoyant units and a magnet is arranged at the midpoint of the length of the main cavity 140. In such alternative embodiments, the solenoid coil is free to slide lengthwise along the rails 120 under gravity as the rails 120 are tilted. The magnet may be an electromagnet in the form of a coil would around the rail with sufficient space for the solenoid coil sliding along the rail 120 to pass therethrough, such that the magnet comprises a coil arranged substantially similarly to the solenoid coil 140 of the illustrated embodiment.

The generator 100 comprises an elongate sleeve shaped flexible waterproof jacket 112 which surrounds and conforms to the shape of the two elongate buoyant units and their interconnecting hinges 160. The jacket 112 includes a sleeve portion 162 which covers and encloses the hinges intermediate the two elongate buoyant units 110.

The casings 118 of the two buoyant units 110 and the hinges 160 that interconnect them are non-ferrous. This advantageously prevents the casing or the hinges from interfering with the motion of the magnet 130 as it slides along the rail 120. For example, the hinges being non-ferrous prevents the magnet from becoming attracted to the hinge 160 and becoming at the hinged end of the buoyant unit 110. The casings 118 and hinges 160 being non-ferrous may also advantageously not rust.

The hinges 160 are advantageously arranged to lock at low wave amplitudes, such that in low wave amplitudes the first and second buoyant units 110 (and rails thereof) are maintained parallel and in line with each other. Such an arrangement provides a longer tilting body which is more efficient in lower amplitude waves.

The electrical housings 116 contain electrical components for deriving a desired output current from the current induced in the solenoid coils 140 of their buoyant unit 110. The electrical housings 116 receive an input alternating current from the solenoid coil 140 and provide an output current to the anchor cables 170 which are connected at the hemi-spherical ends of the buoyant units 110.

A current-carrying anchor cable 170 is connected to each buoyant unit 110 at its hemispherical end. The cables 170 connect the buoyant units to anchoring points 180 embedded the bed 200 of the body of water on whose surface 250 the buoyant units are floating. The cables 170 are sprung so as to allow their length to adjust as the floating generator 100 is displaced (for example, by tides). The cables receive a current from the electronics housing of each buoyant unit and carry it away from the generator to where it is demanded.

The two current-carrying anchor cables 170 are each spring-loaded such that they are extendable in length when sufficient force is applied thereto.

Figures 1 to 4 show the generator 100 as a wave disturbs it from its resting arrangement and passes from one end of the generator 100 to the other. Figure 1 shows the generator floating on relatively calm waters with no large waves 255 present. In Figure 2 am incident wave 255 lifts the hemi-spherical end of a first of the buoyant units, causing the magnet 120 of the buoyant unit 110 to be displaced to the end of the rail proximate to the hinges 160. In Figure 3, the wave has continued to lift the hinged ends of both of the buoyant units, causing the magnets 120 to slide to the ends of the rails 120 adjacent the electrical housings 116. In Figure 4, the wave has reached the far end of the generator and has lifted the hemi-spherical end of the second buoyant unit 110 causing its magnet 130 to be displaced to the end of the rail 120 proximate the hinges 160.

It will be appreciated that the invention has been described by way of example only, and variation may be made to the above described embodiments without departing from the scope of the invention as defined by the claims.

Claims

1. A wave power electric generator comprising one or more buoyant units, each of the one or more buoyant units containing:

a solenoid coil;

a magnet; and a rail which tilts with the buoyant unit and along which either the solenoid coil or the magnet is displaceable under gravity such that the solenoid coil and the magnet are displaced with respect to each other.

2. A wave power electric generator according to claim 1 comprising two or more buoyant units which are rotatable with respect to each other.

3. A wave power electric generator according to claim 2 comprising two buoyant units separated by one or more hinges.

4. A wave power electric generator according to claim 3 wherein the one or more hinges are non-ferrous.

5. A wave power electric generator according to claim 3 or claim 4 wherein the hinges are locked against rotation at low wave amplitudes.

6. A wave power electric generator according to any preceding claim wherein the magnet contained by each buoyant unit is a permanent magnet.

7. A wave power electric generator according to any of claims 1 to 4 wherein the magnet contained by each buoyant unit is an electromagnet.

8. A wave power electric generator according to any preceding claim wherein the magnet is displaceable along the rail with respect to the solenoid coil under gravity as the rail is tilted.

9. A wave power electric generator according to claim 7 wherein the magnet is displaceable along the rail through the solenoid coil under gravity as the rail is tilted.

10. A wave power electric generator according to any preceding claim wherein the rail is threaded such that the solenoid coil or magnet rotates as it is displaced along the rail in at least one direction.

11 .A wave power electric generator according to any preceding claim comprising one or more anchor cables for anchoring the generator to one or more anchoring points on the seabed.

12. A wave power electric generator according to claim 11 wherein at least one of the one or more anchor cables comprises an electrical connection between one or more of the buoyant units and one or more of the anchoring points.

13. A wave power electric generator according to claim 11 or claim 12 wherein the one or more anchoring cables have variable lengths.

14. A wave power electric generator according to any preceding claim comprising buffer stops at each end of each of the rail of each buoyant unit.

15. A wave power electric generator according to any preceding claim wherein each of the one or more buoyant units comprises an impermeable casing surrounding a cavity.

16. A wave power electrical generator according to claim 15 wherein the casing is non-ferrous.

17. A wave power electric generator according to any preceding claim comprising an impermeable flexible jacket which encloses the generator.

Intellectual

Property

Office

Application No: GB1814513.6 Examiner: Mr Peter Middleton