WO2021186177A1

WO2021186177A1 - Wave energy conversion apparatus

Info

Publication number: WO2021186177A1
Application number: PCT/GB2021/050670
Authority: WO
Inventors: James Cameron MCNATT; Christopher Heinz RETZLER; Gabriel SCARLETT; Andrea CAIO
Original assignee: Mocean Energy Ltd
Priority date: 2020-03-18
Filing date: 2021-03-17
Publication date: 2021-09-23
Also published as: GB202003937D0

Abstract

A hinged raft for a wave energy conversion device (WEC) having a first buoyant body and a second buoyant body being hingedly connected to the first buoyant body such that the fore buoyant body can brought into contact with the aft buoyant body (e.g. when the apparatus is in storage or for transportation), the raft having a folded configuration and an open configuration such that, when the raft is in the folded configuration, the first and second bodies are bolded back to form an elongate shape having the hinge joint at one end.

Description

WAVE ENERGY CONVERSION APPARATUS

Field of the invention

The invention relates to the field of wave energy convertors (WECs), machines that transform energy in water waves into a human-usable energy such as electricity, particularly hinged-raft wave energy convertors.

Background to the invention

The field of wave energy conversion is well developed. In particular, wave energy conversion devices (WECs) having two or more joined buoyant or floating bodies are known. Such devices typically take the form of hinged rafts having a power take off which is usually in the hinge joint. Wave motion causes motion of the floating bodies around the hinge joint and thus wave energy is converted into other useable forms of energy (e.g. electrical energy).

However, such devices are by necessity large; they are similar in size to the wavelengths of the waves from which the convert energy, which is required in order for them to do so efficiently. As such positioning them in locations where they are most effective (i.e. at sea) can present a challenge. Further to this, where the joined buoyant bodies of a WEC can collide with each other (e.g. via rotation about a hinge joint) this can lead to damage of the wave energy conversion devices and, in turn, to reduced efficiency of wave energy extraction and in some cases total loss of the device. Accordingly, the invention seeks to provide an improved WEC which is more portable and less susceptible to damage, as well as a method of extracting wave energy with such a WEC.

Summary of the invention

According to a first aspect of the invention there is provided a hinged raft for a wave energy conversion device (WEC) comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end.

Typically, when the hinged raft is in the open configuration, the first and second bodies extend in opposite directions away from the hinge joint, when viewed in plan. Accordingly, when the hinged raft is in the open configuration, the first and second bodies may rotate relative to each other around the hinge joint. Typically, (in use) when the hinged raft is in the open configuration, at least one of the first and second bodies (and optionally the hinge joint) is at least partially submerged beneath a still water surface in a still water rest position. Typically (in use), when the hinged raft is in the open configuration, the first and second bodies are parallel to the still water surface and transverse to the direction of wave propagation and extend in opposite directions away from the hinge joint.

Typically, the range of rotation of the first and second bodies via the hinge joint is sufficiently great that at least part of the at least one of the outer surfaces of the first body can be brought into (e.g. mechanical) contact with at least part of at least one of the outer surfaces of the second body (e.g. in the folded configuration).

Accordingly, when in the open configuration (in water, i.e. in use), the first and second bodies can move around the hinge joint (e.g. in flexure). The first and second bodies are typically caused to move by the action of waves upon the first and second bodies. For example, the first and second bodies may sag or hog around the hinge joint. It will be appreciated that the motion of the hinged raft (and/or of the first and second bodies) will be dependent upon the motion of waves and that this motion may thus include rolling, pitching, surging, heaving, etc. However, in the open configuration the first and second bodies nevertheless extend away from the hinge joint. The hinged raft as a whole may move due to wave action and may travel and/or rotate. Wave energy is transferred to the first and second bodies, causing their flexure around the hinge joint and thus the energy may be converted into one or more (other) useable forms, for example the wave energy may be converted to electrical energy. The open configuration may therefore be considered to be an operating configuration.

Further to this, in the folded configuration, the total length of the hinged raft is reduced. For example, the total length of the hinged raft in the folded configuration may be the length of the longer of the two floating bodies and the length of the hinge. In contrast, the total length of the hinged raft in the open configuration may be up to the length of the first floating body, the length of the hinge, and the length of the second floating body. Therefore, the folded configuration enables the hinged raft to be more easily stowed, stored, and/or transported. For example, the hinged raft may be stored in a shipping container and transported to an ocean site where it is intended for use, and then transitioned into the open configuration for use.

In use, the rotational motion of the first and second buoyant bodies relative to each other about the hinge (i.e. flexing motion typically caused by wave motion) can be converted to useable power, for example electrical energy or hydraulic energy. The hinge joint is typically coupled to a power take off (PTO) system. The PTO may comprise one or more direct drive electrical generators, optionally integrated with the hinge joint. The PTO may comprise one or more gearbox generators. Typically, the PTO generates power as a result of the flexure of the first and second buoyant bodies around the hinge joint.

Preferably, when the raft is in the folded configuration the first and second bodies at least partially overlap with each other. The folded configuration may comprise the first and second bodies cooperating with each other.

When the raft is in the open configuration, it may be that the first and second bodies are in one of a range of positions in which a component of the direction in which the first body extends away from the hinge joint is opposite to a component of the direction in which the second body extends away from the hinge joint. In the open configuration, the first and second bodies typically extend away from the hinge joint in opposite directions, wherein a component of the direction in which each of the first and second bodies extend is parallel to the still water surface.

The first (e.g. fore) and second (e.g. aft) buoyant bodies are preferably elongate buoyant bodies in that each has a length greater than its width and/or its depth, wherein the length is defined as the dimension extending away from the hinge joint. Similarly, when the raft is in the folded configuration, the (e.g. elongate) object formed by the elongate bodies being folded back on each other is typically also elongate in that the said shape has a length greater than it’s width and/or its depth, wherein its length is defined as the dimension extending away from the hinge joint.

Although in some embodiments the first and second buoyant bodies may be substantially the same size and shape, typically one buoyant body has a length greater than that of the other buoyant body. In some embodiments one buoyant body may have a width and/or depth greater than the respective width and/or depth of the other buoyant body.

The (e.g. elongate, folded) object may have a length which is the length of the longer of the first and second buoyant bodies and the hinge joint. The (e.g. elongate, folded) object may have a height which is the combined height of the first and second buoyant bodies and/or the height of the hinge joint. The (e.g. elongate, folded) object may have a width which is the width of the wider of the first and second buoyant bodies and/or the width of the hinge joint.

The folded configuration may be a configuration in which the raft may be stored and/or transported.

Typically, the (e.g. elongate, folded) object has dimensions such that it will fit within a standard shipping container, optionally when placed on one or more pallets. For example, the (e.g. elongate, folded) object may have a length of less than 12.9 m (e.g. between 10 m and 12 m), or less than 5.9 m, or less than 2.9 m (e.g. when in the folded configuration). The (e.g. elongate, folded) object may have a length of more than 1 m, or more than 1.5 m, preferably more than 2 m (e.g. when in the folded configuration). The (e.g. elongate, folded) object may have a width of less than 2.5 m, preferably less than 2.3 m. For example, the first floating body may have a width of less than 2.5 m, preferably less than 2.3 m and/or the second floating body may have a width of less than 2.5 m, preferably less than 2.3 m The (e.g. elongate, folded) object may have a width of more than 1 m. The first and/or second floating body may have a width of more than 1 m. The (e.g. elongate, folded) object may have a height of less than 2.5 m, preferably less than 2.3 m. The first and/or second floating body may have a height of less than 2.5 m, preferably less than 2.3 m The (e.g. elongate, folded) object may have a height of more than 1 m. The first and/or second floating body may have a height of more than 1 m.

Although typically the first and second floating bodies are not of the same width and/or length, in some embodiments the first and second floating bodies may be of the same width and/or length. Although typically the first and second floating bodies are of the same height, in some embodiments the first and second floating bodies may be of different heights.

Typically, the ratio of the total length of the first and second floating bodies and the hinge (e.g. the length of the hinged raft when in the (fully) open configuration) to the total length of the (e.g. elongate, folded) object (e.g. the length of the hinged raft when in the (fully) folded configuration) is above 0.5, or preferably above 0.55, or above 0.6. Typically, the ratio of the total length of the first and second floating bodies and the hinge (e.g. the length of the hinged raft when in the (fully) open configuration) to the total length of the (e.g. elongate, folded) object (e.g. the length of the hinged raft when in the (fully) folded configuration) is below 0.7, preferably below 0.65. Preferably, transitioning the hinged raft from the open configuration to the folding configuration results in a decrease in total length of the raft of more than 25%, preferably above 30%. Preferably, transitioning the hinged raft from the open configuration to the folding configuration results in a decrease in total length of the raft of less than 50%, preferably less than 40%.

When the raft is in the open configuration, it may be that the first and second bodies are in one of a range of positions in which no part of the outer surfaces of the first and second bodies are in contact with each other (i.e. except via the hinge joint).

Typically, the first (e.g. fore, elongate) buoyant body comprises a wave receiving channel, the wave receiving channel having a wave receiving opening. Typically, the second (e.g. aft, elongate) buoyant body comprises a wave receiving channel, the wave receiving channel having a wave receiving opening. When the raft is in the open configuration, the first and second (elongate) buoyant bodies may rotate, relative to each other, about the hinge joint. For example, the first and second (elongate) buoyant bodies may rotate about an axis parallel to the still water surface. The first and second (elongate) buoyant bodies may rotate in a direction transverse to a direction of wave propagation.

When the raft is in the open configuration and is in water, although the first and second (elongate) buoyant bodies are moveable relative to each other, about the hinge joint (such motion typically being caused by waves), the presence of the water makes it difficult to bring the (e.g. lower surfaces of) the first and second (elongate) bodies into contact with each other. Without wishing to be bound by theory it would appear that this effect is analogous to a squeezed film effect, leading to increasingly great forces being necessary to reduce the angle of separation between the (e.g. lower surfaces of) the first and second (elongate) bodies as the said angle gets smaller. This provides the advantage that there is a reduced risk of the first and second (elongate) bodies being brought into contact with each other in an uncontrolled manner (e.g. at speed) which could otherwise lead to damage of the hinged raft. It has been surprisingly found that, providing the first and second (elongate) bodies with lower surfaces which each comprise a portion which is conformal with a portion of the other lower surface (preferably wherein the said portion is flat) enhances this squeezed film effect.

Typically, the first and second bodies each comprise at least one lower surface (e.g. a surface which is at least partially submerged beneath the still water surface in use). Preferably, at least part of at least one of the lower surfaces of the first body is conformal to at least part of at least one of the lower surfaces of the second body. Optionally, at least part of at least one of each of the lower surfaces of the first and second bodies are flat (e.g. has a peak-to-peak flatness of less than 5 cm, preferably less than 2 cm, more preferably less than 1 cm). Accordingly, the first and second bodies can be brought into close (e.g. mechanical) contact with each other (i.e. with no space therebetween) at the conformal and/or flat surfaces (for example, when the raft is in the folded configuration).

Typically, the first buoyant body comprises an upper surface (at least a portion of which may be flat). Typically, the upper surface of the first buoyant body is opposite to the at least one lower surface. Typically, the upper surface of the first buoyant body is at least partially above the still water surface in use. Typically, the second buoyant body comprises an upper surface (at least a portion of which may be flat). Typically, the upper surface of the second buoyant body is opposite to the at least one lower surface. Typically, the upper surface of the second buoyant body is at least partially above the still water surface in use.

Typically, when the raft is in the open configuration there is an angle of separation between the lower surface of the first buoyant body and the second buoyant body, the said angle being greater than 5°, preferably greater than 20°, optionally greater than 60°. Typically, when the raft is in the folded configuration the said angle of separation between the lower surface of the first buoyant body and the second buoyant body is less than 5°, preferably less than 2°, optionally less than 1°. When the raft is in the folded configuration, the said angle of separation between the lower surface of the first buoyant body and the lower surface of the second buoyant body may be (e.g. substantially) 0°.

Where the first and/or second buoyant body comprises a recess, the recess is typically a through-bore, i.e. it is a complete hole through the hull of the first and/or second buoyant body. This provides the advantage that fluid (e.g. liquid, optionally liquid water and/or air) may flow through the recess, which is particularly important when the hinged raft is transitioning between the open configuration and the folded configuration. However, it may be that in some embodiments the recess is a closed-ended recess. In some embodiments the recess may comprise a mesh or a net. The mesh or net may allow fluid (e.g. liquid, e.g. liquid water) to flow therethrough but prevent solid matter (e.g. rocks, stones, debris, etc.) from passing through the recess.

Where at least part of at least one of the lower surfaces of the first body is conformal to at least part of at least one of the lower surfaces of the second body, the part of each of the said surface comprises at least 30%, at least 50%, or preferably at least 75% of the total surface area of the lower surface of the first and/or second body. Where at least part of at least one of the lower surfaces of the first body is flat and at least part of at least one of the lower surfaces of the second body is flat, the part of each of the said surface comprises at least 30%, at least 50%, or preferably at least 75% of the total surface area of the lower surface of the first and/or second body.

Where at least part of at least one of the lower surfaces of the first body is conformal to at least part of at least one of the lower surfaces of the second body, the part of each of the said surface comprises a surface area of at least 1 m², preferably at least 2 m². Where at least part of at least one of the lower surfaces of the first body is conformal to at least part of at least one of the lower surfaces of the second body, the part of each of the said surface comprises a surface area of less than 30 m².

Optionally, the first (e.g. fore, elongate) buoyant body may comprise a recess and at least a portion of the second (e.g. aft, elongate) buoyant body may extend into (e.g. fit into and/or cooperate with) the recess of the first (e.g. fore, elongate) buoyant body, e.g. when the hinged raft is in the folded configuration. Optionally, the second (e.g. fore, elongate) buoyant body may comprise a recess and at least a portion of the first (e.g. fore, elongate) buoyant body may cooperate with the recess of the second (e.g. aft) buoyant body, e.g. when the hinged raft is in the folded configuration. Accordingly, the first and second bodies may cooperate with one another in the folded configuration. The provision of a recess in the first (e.g. fore, elongate) buoyant body (or alternatively in the second (e.g. aft, elongate) buoyant body) into which at least a portion of second (e.g. aft, elongate) buoyant body (or alternatively a portion of the first (e.g. fore, elongate) buoyant body) may extend (e.g. fit into and/or cooperate with) provides the advantage that the hinged raft may be folded into a more compact object (i.e. when the hinged raft is in the folded configuration) than would otherwise be the case.

Where provided, the recess of the first (e.g. fore, elongate) body (or optionally the recess of the second (e.g. aft, elongate) body) may be configured to receive a protrusion of the second (e.g. aft, elongate) body (or alternatively a protrusion of the first (e.g. fore, elongate) body). Said protrusion may at least partially extend into (e.g. fit into and/or cooperate with) the recess, e.g. when the raft is in the folded configuration.

Typically, the wave receiving channel of the first (e.g. fore, elongate) buoyant body comprises a (preferably sloping) base. Typically, the wave receiving channel of the and second (e.g. aft, elongate) buoyant bodies comprises a (preferably sloping) base. Preferably both the (sloping) base and the wave receiving opening of the first (e.g. fore, elongate) and/or second (e.g. aft, elongate) buoyant body is (or are each) provided between opposing first and second side walls, and at least part of each of the (sloping) base(s) extend(s) beneath a still water surface in a still water rest position (i.e. in use, when the hinged raft is in the open configuration). However, in some embodiments the sloping base may be entirely below the still water surface in the still water rest position (i.e. in use, when the hinged raft is in the open configuration). Typically, (e.g. each of the) (sloping) base(s) extend(s) from an end wall of the corresponding wave receiving channel, each wave receiving channel being at least partly defined by first and second side walls, the (sloping) base and the end wall. The end wall may be vertical (i.e. parallel to the horizontal) or may be sloping.

Typically, at least a portion of the wave receiving opening is provided at an end of the wave receiving channel. The said end of the wave receiving channel at which the said at least a portion of the wave receiving opening is provided may be a first end of the wave receiving channel. The end wall may be provided at a second end of the wave receiving channel opposite the first end. The first end of the wave receiving channel may coincide with the (e.g. fore or aft) end of the buoyant body (e.g. in use, e.g. when the raft is in the open configuration). Preferably, the wave receiving opening is submerged beneath the still water surface (e.g. in use, when the hinged raft is in the open configuration).

Typically, the first (e.g. fore, elongate) body and the second (e.g. aft, elongate) body and the hinge joint are configured such that flexion of the first and second bodies around the hinge joint converts wave energy from waves received through the wave receiving opening to some other form of energy, for example to drive (e.g. electrical or hydraulic) power generation or storage apparatus, or to carry out another activity, (e.g. in use, e.g. driving a pump (e.g. a water pump) or compressor, or operating a desalinator. Typically, the sloping base is configured to enhance resonance effects such that resonant modes of the first (e.g. fore, elongate) body and/or the second (e.g. aft, elongate) body and/or of the hinged raft. The excitation of such resonant modes can enhance the portion of received wave energy which is converted. Wave energy may be converted from to electrical power (e.g. in use). Wave energy may be converted to fluid power.

It may be that the said wave receiving channel has one or more channel resonant modes. It may be that the excitation of the one or more channel resonant modes can may be caused by excitation of the said wave receiving channel at one or more corresponding channel resonant frequencies, the one or more channel resonant frequencies being at least partly defined by the sloping base and/or the first and second side walls (and/or the end wall, where provided). The said channel may be configured to cause excitation of the one or more channel resonant modes (i.e. in use), and thereby to cause resonance (typically within the channel) of waves received by the wave receiving channel through the wave receiving opening and having the said channel resonant frequencies.

Typically, resonance of the received waves increases the quantity of wave energy extracted (and so converted), for example the resonance of the received waves may increase the quantity of power generated. Typically, the resonance increases the force and/or work done on the buoyant body, in a downward/upward (heave), forward/backward (surge) and/or rotational (pitch) direction, by the waves, compared to what the force and/or work done would be in the absence of the channel with a sloping base (e.g. if there was no channel, or if there was a channel with a base which is horizontal in the still water rest position).

It may be that the said wave receiving channel is configured to cause resonance of the waves (i.e. in use), within a wavelength range, that are received though the wave receiving opening.

The range of wavelengths for which there are resonance effects (leading to enhanced forces on the floating body), and the peak wavelength (the wavelength corresponding to the channel resonant frequency), are defined by the configuration of the water receiving channel, e.g. by its breadth, depth (relative to the water line in a still water rest position) and slope profile. The range of wavelengths and the peak wavelength can be determined empirically or through simulation for a given channel configuration.

The sloping base may be curved. The sloping base may be concave. The sloping base may be flat. It may be that the sloping base is longer in a direction along the length of the channel (e.g. a longitudinal axis of the channel) than it is wide, e.g. the sloping base may be elongate. It may be that the sloping base is more than three times, or more than four times longer than it is wide. Typically, the sloping base is less than six times longer than it is wide. The length of the channel is typically aligned with the direction of travel of incident waves, i.e. in use.

The lower surface of the first floating body may extend smoothly into the sloping base, an end surface and/or the top surface and/or one or more other surfaces of the first floating body. The lower surface of the second floating body may extend smoothly into the sloping base, and/or the top surface and/or one or more other surfaces of the second floating body. Preferably the hinge comprises a hinge axis (e.g. about which the first (e.g. fore) and second (e.g. aft) buoyant bodies rotate (e.g. in flexion). Preferably, the hinge axis is coincident with the mean plane of the lower surfaces of the first and second bodies. The hinge axis may be at least partially submerged beneath the still water surface (e.g. in use) however, it may in some embodiments float above the still water surface. The hinge is preferably buoyant.

Preferably, the first floating body comprises pins and the second floating body comprises holes configured to retain said pins. Optionally, the second floating body comprises pins and the first floating body comprises holes configured to retain said pins. Preferably the hinge is connected via the pins (e.g. the pins pass though the hinge). Preferably the hinge comprises a generator and/or a PTO. Preferably the pins further connect to a (e.g. the) PTO. The first and/or second floating body may comprise power electronics and/or electrical systems as are known in the art.

Each of the opposing first and/or second side walls may be braced or otherwise supported. This provides the advantage of limiting damage to the side walls and/or wave receiving channels, for example in extreme weather conditions. Optionally, however, each of the opposing first and/or second side walls may (e.g. partially) comprise one or more grid sections (e.g. there may be one or more holes through the side walls). This lowers the overall strength of opposing first and/or second side walls, but also reduces the amount of material required for manufacturing the hinged raft, and therefore correspondingly reduces manufacturing costs. Each of the opposing first and second side walls may comprise one or more (e.g. supporting and/or strengthening) trusses.

Typically, the second (e.g. aft) buoyant body comprises a recess which receives and retains the wave receiving channel of the first (e.g. fore) buoyant body when the lower surface of the first (e.g. fore) buoyant body is brought into contact with the second (e.g. aft) buoyant body (e.g. when the hinged raft is in the folded configuration). However, in some embodiments, the first (e.g. fore) buoyant body comprises a recess which receives and retains the wave receiving channel of the second (e.g. aft) buoyant body when the lower surface of the second (e.g. aft) buoyant body is brought into contact with the first (e.g. fore) buoyant body (e.g. when the hinged raft is in the folded configuration). Where the second (e.g. aft) buoyant body comprises a said recess, the first (e.g. fore) aft buoyant body typically does not comprise a recess, however it may do so. Where the first (fore) buoyant body comprises a said recess, the second (e.g. aft) buoyant body typically does not comprise a recess, however it may do so.

Typically, the recess comprises a channel (or a through-bore) which passes completely through the second (e.g. aft) (or optionally the first (e.g. fore)) buoyant body. This provides the advantage of allowing fluid (e.g. air and/or liquid, e.g. water) to pass through the buoyant body via the recess without trapping said fluid which may otherwise limit the minimum angle between the lower surface of the first (e.g. fore) body and the lower surface of the second (e.g. aft) body).

Preferably, the first and second bodies each comprise at least one upper surface. Preferably, the at least one upper surface is substantially flat. Preferably, the at least one upper surface is above the still water surface in use (i.e. when the hinged raft is in the open configuration). The at least one upper surface may comprise one or more monitors, e.g. for monitoring weather and/or wave conditions and/or for monitoring the hinged raft. When the raft is in the open configuration the at least one upper surface of one or both of the elongate buoyant bodies may extend away from the hinge joint in a direction which has a component that is parallel to the still water surface.

It may be that the hinged raft has an anti-fouling coating (e.g. paint) on the external surface to restrict the growth of organisms. It may be that the hinged raft has an anti fouling coating (e.g. paint) on the external surface to limit oxidisation (e.g. rusting).

The first (e.g. fore) buoyant body preferably floats in (liquid) water (e.g. in saltwater and/or fresh water), e.g. in use. The second (e.g. aft) floating body preferably floats in (liquid) water (e.g. in saltwater and/or in fresh water, e.g. in use. The hinge preferably floats in (liquid) water (e.g. in saltwater and/or in fresh water), e.g. in use.

Each of the first and/or second bodies may have a buoyancy such that at least some (e.g. at least 5%, or at least 10%, or at least 20%) of the mass of the or each buoyant body is above the water line in a still water rest position, e.g. in use, for example when the raft is in the open configuration. The or each buoyant body may have a buoyancy such that at least 50% of the mass of the buoyant body is below the water line in a still water rest position, e.g. in use, for example when the raft is in the open configuration.

It may be that the hinged raft (e.g. one or more of the buoyant bodies, or the hinge, of the hinged raft) is tethered to an anchor in use. According to a second aspect of the invention there is provided an apparatus comprising a container, the container retaining a hinged raft (e.g. at least one hinged raft, optionally two or more hinged rafts) for a wave energy conversion device (WEC) comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the (or each) hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end.

Typically, the container retains the (or each) hinged raft in the folded configuration. Typically, the container is a shipping container. The container may further comprise one or more support structures (e.g. one or more support skids). The container may further comprise packaging materials.

According to a third aspect of the invention there is provided a kit comprising a container (optionally a shipping container), the shipping container retaining a hinged raft (e.g. at least one hinged raft, optionally two or more hinged rafts) for a wave energy conversion device (WEC) comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the (or each) hinged raft having a folded configuration and an open configuration, wherein, when the (or each) raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end.

The kit may further comprise one or more support structures (e.g. one or more support skids). The kit may further comprise packaging materials.

According to a fourth aspect of the invention there is provided a method of extracting wave energy, the method comprising, providing a hinged raft for a wave energy conversion device (WEC) comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end, and introducing the raft into water in the open configuration, such that the motion of waves in the water causes rotational motion of the first and second buoyant bodies relative to each other around the hinge joint.

The method may be a method of converting wave energy (to another form of energy). The wave energy may for example be used to drive (e.g. electrical or hydraulic) power generation or storage apparatus. Electrical or hydraulic power is thereby generated or stored. Wave energy may be converted to useful work, for example to pump liquid (e.g. in a water pump or desalinator).

The method may comprise the initial step of measuring properties of the waves at a location, averaged over a period of time, and selecting each of the buoyant body from amongst a plurality of possible buoyant bodies having different configurations (e.g. different distances between the first and second side walls) taking into account the measured properties.

According to a fifth aspect of the invention there is provided a method of installing a hinged raft for a WEC, the method comprising, transporting a container to a predetermined location, the container retaining a hinged raft for a WEC, comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end; removing the hinged raft from the shipping container in the folded configuration; introducing the hinged raft into a body of water at the predetermined location; and causing the hinged raft to transition into the open configuration.

It may be that the step of causing the hinged raft to transition into the open configuration comprise providing an (e.g. small) impetus at the hinge joint to thereby cause the first and second elongate buoyant bodies to rotate around the hinge joint in opposite directions from each other. The (e.g. small) impetus at the hinge joint may comprise an (e.g. small) force applied to encourage sagging of the hinged raft.

It may be that the step of causing the hinged raft to transition into the open configuration comprise providing a driving force to thereby cause the first and second elongate buoyant bodies to rotate around the hinge joint in opposite directions from each other, optionally until the (e.g. upper surfaces of the) first and second elongate bodies are parallel to the still water surface.

According to a sixth aspect of the invention there is provided a method of uninstalling a hinged raft for a WEC, the method comprising, transporting a container to a predetermined location wherein a hinged raft for a WEC is installed in a body of water, the WEC comprising: a first (e.g. fore) elongate buoyant body; and a second (e.g. aft) elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an (e.g. elongate) object having the hinge joint at one end; causing the (installed) hinged raft to transition from the open configuration into the folded configuration; and (optionally) removing the hinged raft from the body of water at the predetermined location; and (optionally) introducing the hinged raft into a (e.g. shipping) container in the folded configuration.

The method may comprise introducing the hinged raft into the (e.g. shipping) container in the folded configuration with one or more support structures (e.g. one or more support skids) and/or packaging materials. The method may comprise storing the hinged raft in the (e.g. shipping) container and/or transporting the hinged raft in the (e.g. shipping) container. The first and/or second buoyant bodies and/or the hinge joint may comprise fibre glass. The first and/or second buoyant bodies and/or the hinge joint may comprise metal (e.g. aluminium or steel). The first and/or second buoyant bodies and/or the hinge joint may comprise plastics material(s). The skilled person will appreciate that the first and/or second buoyant bodies and/or the hinge joint may comprise other suitable materials.

The raft may be tethered to an anchor, optionally by a joint, optionally by the hinge joint (e.g. the raft may be tethered via a swivel). Power and/or communications signals may be transferred to and/or from the raft via (e.g. via a swivel and/or via a slipring).

The hinged raft may comprise one or more further buoyant bodies, optinally these may be connected by one or more further hinge joints. The WEC may comprise one or more (e.g. further) hinged raft(s), optionally an array of hinged rafts. Where more than one hinged rafts is provided, each hinged raft may comprise an individual mooring, umbilical and/or foundation infrastructure, however each hinged raft may share a common mooring, umbilical and/or foundation structure with one or more of the or each other hinged raft (and optionally all hinged raft).

Although the hinge joint typically comprises a hinge it may in some embodiments comprise a sliding joint.

It will be understood that “length” is the major dimension of the first and/or second floating body, or of the hinged raft as a whole, “width” is the dimension parallel to the axis of rotation of the hinge joint and “height” is the dimension orthogonal to width and length, typically vertical extent in the still water rest position.

The method may comprise an initial step of measuring properties of the waves at a location, averaged over a period of time (e.g. a day, a week, a month, a year, etc.), and selecting the buoyant body from amongst a plurality of possible buoyant bodies having different configuration (e.g. different shapes and/or sizes) taking into account the measured properties.

Description of the Drawings

An example embodiment of the present invention will now be illustrated with reference to the following Figures in which: Figure 1 is a diagram of a hinged raft for a wave energy conversion device (WEC) in the open configuration with a fore perspective view;

Figure 2 is a diagram of a hinged raft for a wave energy conversion device in the open configuration with an aft perspective view;

Figure 3 is a diagram of a hinged raft for a wave every conversion device in the folded configuration with a fore perspective view;

Figure 4 is a diagram of a hinged raft for a wave every conversion device in the folded configuration with an aft perspective view;

Figure 5 is a cross-sectional side elevation diagram of a hinged raft for a wave energy conversion device in the folded configuration;

Figure 6 is a cross-sectional side elevation diagram of a hinged raft for a wave energy conversion device at a transition point between the folded and the open configuration (i.e. in a partially open state);

Figure 7 is a cross-sectional fore perspective diagram of a hinged raft for a wave energy conversion device at a transition point between the folded and the open configuration (i.e. in a partially open state);

Figure 8 is a cross-sectional aft perspective diagram of a hinged raft for a wave energy conversion device at a transition point between the folded and the open configuration (i.e. in a partially open state);

Figure 9 is a cut-away diagram of a hinged raft for a WEC device in the folded configuration in a shipping container, with an aft perspective view;

Figure 10 is an enlarged perspective view of a wave channel of a hinged raft of a wave energy conversion device;

Figure 11 is a further cut-away diagram of a perspective view of a hinged raft for a WEC in the folded configuration in a shipping container; and Figure 12 is a diagram of a perspective view of a hinged raft for a WEC in the folded configuration being removed from (or placed within) a shipping container.

Detailed description of an example embodiment

Figures 1 and 2 are diagrams of a hinged raft wave energy conversion device (WEC) according to the invention wherein the hinged raft is in the open configuration. Figures 3 to 5 are diagrams of a hinged raft WEC according to the invention wherein the hinged raft is in the folded configuration.

With reference to Figures 1 and 2, a hinged raft for a (WEC) according to the invention takes the form of a hinged raft 1 having a first buoyant body 2 and a second buoyant body 8 which are joined by a hinge 6 such that they can freely rotate with one rotational degree of freedom, relative to each other. In Figure 1 , the direction of wave propagation is indicated with arrow W. The first buoyant body 2 can thus be seen as a fore buoyant body and the second buoyant body 8 can thus be seen as an aft buoyant body. Each of the first 2 and second 8 buoyant bodies are partially submerged beneath the still water line 9. The first (fore) buoyant body 4 has a wave channel 2, an upper surface 14, and a lower (conformal) surface 18. The second (aft) buoyant body 8 has a wave channel 12, an upper surface 16, a lower (conformal) surface 20 and a recess 10. In a preferred embodiment, the lower (conformal) surface 18 of the first (fore) buoyant body 2 is flat and the lower (conformal) surface 20 of the second (aft) buoyant body 8 is flat.

An electricity generator, or other energy conversion apparatus, such as a pump (e.g. a hydraulic pump or water pump) may be located in the hinge 6 region to convert received wave energy into another form (e.g. electricity, fluid power, etc.)

The hinged raft 1 has an open configuration and a folded configuration. The folded configuration is defined by the lower (conformal) surface 18 of the first (fore) buoyant body 4 being in contact with the lower (conformal) surface 20 of the second (aft) buoyant body 8, i.e. such that the first and second bodies are folded back on each other (via rotation around the hinge joint). The open configuration is defined by the angle between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 being greater than 0°, i.e. the hinged raft is in the open configuration when the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 are not in contact with each other. The lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body are both substantially flat, each having a peak-to-peak flatness of less than 5 cm. This flatness allows close contact between the two lower (conformal) surfaces. The upper surface 14 of the first (fore) buoyant body 4 and the upper surface 16 of the second (aft) buoyant body are both substantially flat, providing platforms when the hinged raft 1 is in the open configuration. The upper surface 14 of the first (fore) buoyant body has monitors mounted on it, for monitoring weather and/or wave conditions and/or for monitoring the hinged raft 1.

The recess 10 of the second (aft) buoyant body 8 is sized and shaped to receive and retain the wave channel 2 of the first (fore) buoyant body 4, i.e. when the hinged raft 1 is in the folded configuration or when the angle between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 is small (e.g. between 0° and 20°). Thus the first (fore) buoyant body 4 may be folded around the hinge joint 6 and brought into contact with the second (aft) buoyant body 8, and the wave channel 2 of the first (fore) buoyant body 4 may be folded into the recess 10 of the second (aft) buoyant body 8.

Figures 1 and 2 are diagrams of the hinged raft 1 in a fully open configuration, wherein the angle between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 is close to 180°. Flowever, it will be understood that the open configuration also includes a range of angles of separation between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8

In an example embodiment, the minimum total length of an example raft (i.e. a raft in the folded configuration) is 11.5 m, the maximum total length of the example raft (i.e. a raft in the open configuration) is 18.4 m, the total height of the raft is 2.1 m, the width of the first floating body is 1.6 m and the width of the second floating body is 2.1 m. Accordingly, the ratio of the length of the raft in the folded configuration to the length of the raft in the open configuration is 0.625 and transitioning the raft from the open configuration to the folded configuration thus causes a decrease in total length of 37.5%. Figures 3 and 4 are diagrams of the hinged raft 1 in the folded configuration, wherein the angle between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 is substantially 0° (e.g. less than 2°).

Figures 5 to 8 are cross-sectional diagrams of the hinged raft 1, as the raft 1 is transitioning from the folded configuration to the fully open configuration (e.g. as in figures 1 and 2).

Figures 9 is a diagram of the hinged raft 1 in the folded configuration, within a shipping container 22.

The wave channel 2 of the first (fore) buoyant body 4 and the wave channel 12 of the second (aft) buoyant body 8 (shown enlarged, as an example, in figure 10) both have a sloping base 24 which extends from a first end 34 to a second end 32, from where an end wall 26 extends at a steeper angle. Side walls 28 and 30 are provided at opposite lateral sides of the sloping base 24. In this example, the wave channels are at least partially submerged (i.e. in use, when the raft 1 is in the open configuration), and the side walls extend above the still water line 9.

The hinged raft 1 is stored and transported in the folded configuration. The hinged raft 1 is caused to transition into the open configuration in water. The hinged raft 1 may then be used to convert wave energy into other forms of energy when the hinged raft 1 is in the open configuration in water. As such, the open configuration may be considered to be an operating configuration. Similarly, the folded configuration may be considered to be a storage configuration.

After causing the hinged raft to transition into the open configuration, it is possible to later cause the hinged raft to transition into the folded configuration (e.g. so that it may be stowed and/or transported to a different site).

In one application, the hinged raft 1 is introduced into a body of water in the folded configuration and a force is applied (optionally via torque at the hinge 6 or, for example, via a control line) to encourage the first (fore) buoyant body 4 to separate from (i.e. to rotate away from) the second (aft) buoyant body 8. When a small angle of separation is achieved, water enters the space between the first (fore) 4 and second (aft) 8 bodies. At an angle of approximately 90° of separation between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 the speed of separation increases. At an angle of 120° of separation between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 an active force would be required to bring the reduce the angle between the lower surfaces. At an angle of 180° of separation between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 the raft 1 is fully open (e.g. as shown in figures 1 and 2). The transition between the folded configuration and the open configuration generally takes under 1 minute (e.g. several seconds) however the skilled person will appreciate that this will depend on water conditions, forces applied, etc.

The fully open configuration as shown in figures 1 and 2 corresponds to the typical average (mean) positions of the first (fore) buoyant body 4 and the second (aft) buoyant body 8 of the raft 1, relative to each other, when the raft 1 is at rest in still water. In the fully open configuration and in still water, the wave channel 2 of the first (fore) buoyant body 4 and the wave channel 12 of the second (aft) buoyant body 8 are both at least partially submerged beneath the still water line 9. In use, waves enter the wave channel 2 of the first (for) buoyant body 4 and/or the wave channel 12 of the second (aft) buoyant body 8, causing flexing motion of the respective buoyant bodies, relative to each other, via rotation around the hinge 6.

It has been surprisingly found that, providing a hinged raft 1 with two buoyant bodies, the lower surfaces of which can be brought into close contact with each other provides the advantage that, when the bodies are rotated close to each other (e.g. by wave motion) water gets trapped between the two bodies preventing them from colliding with each other. Without wishing to be bound by theory it would appear that this effect is analogous to a squeezed film effect, leading to increasingly great forces being necessary to reduce the angle of separation between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 as the said angle gets smaller. This effect does not occur when the raft is in air, so it is possible to move the raft into the folded configuration when it is not in water, thus providing the further advantage that the raft can then be transported conveniently, for example by placing it within a shipping container.

It will be noted that the provision of a hinged raft WEC having first and second floating bodies which may be folded back on each other in a folded configuration allows for geometries of floating bodies wherein a reduced quantity of materials (e.g. metal, fibreglass or other construction materials) may be used in comparison to other hinged raft WECs.

A further advantage of the hinged raft WEC 1 of the present invention is that in the folded configuration it is more portable than known hinge raft WECs, because the folded configuration can be more easily stowed and/or stored, for example in a shipping container (as shown in Figure 9, see also Figures 11 and 12). This means that the hinged raft WEC 1 of the present invention is particularly suitable for providing energy at remote sites which may temporarily require (e.g. additional) energy for completing a particular task, as it can be brought to such sites quickly and installed quickly. However, it will be appreciated that the hinged raft WEC 1 of the present invention is also suitable for being installed and operated on a long term basis.

Energy extracted from waves by the WEC is converted into another human-usable form using a power take-off such as an electricity generator, or pump, for example.

The hinged raft 1 may be connected to the sea floor, a wall, to one or more anchors, or optionally may be connected to an anchor that is submerged but not fixed.

The first (fore) buoyant body 4 and the second (aft) buoyant body 8, as well as the hinge 6, are formed from metal (e.g. aluminium or steel), fibreglass, or one or more plastics material(s). The first (fore) buoyant body 4 and the second (aft) buoyant body 8 each have a buoyant core (e.g. a sealed compartment containing air or another gas, or a vacuum, or a low density plastics material) and optionally one or more ballast chambers, such that the average (e.g. mean) density of the hinged raft 1 is less than the density of water (typically sea water, optionally fresh water if, for example, the hinged raft 1 is intended for use in a fresh water lake). The external surfaces of the hinged raft, including the external surfaces of the first 4 and second 8 buoyant bodies and the hinge 6 are treated with an anti-fouling coating (e.g. paint) to limit the growth of organisms. The anti-fouling coating also limits oxidation.

It is not required that the wave channels have the shapes shown in figures 1 to 10. For example, the bases may have variable slope, the side walls need not be parallel, the end wall may be sloped to a greater or lesser degree, or may be vertical. The tops of the side walls may or may not be sloped. The side walls may or may not extend the whole way to the first end of the sloping base. The sloping base may be curved. The sloping base may have a curved profile, for example they may be concave. The sloping base may blend into the end wall. The wave channels may have different dimensions, for example in order to have different resonant modes, which may be excited by waves of correspondingly different wavelengths.

The dimensions of the channels, particularly the spacing between the side walls, may be selected depending on the location where the hinged raft 1 is to be installed. The properties of waves at the location, notably the average period between waves and/or the power spectral density of waves, are measured over a period of time (e.g. a day, week, month or year). A channel with dimensions which will prove optimal at that location given the measured wave properties is then designed or selected from amongst a plurality of available configurations. In particular, the beam of the channel is determined as a fraction of the wavelength associated with the measured mean period between waves, taking into account measurements and/or simulations. Thus, hinged rafts for WECs may be provided with channels having different dimensions at different locations which have waves with different properties.

Although the recess 10 is typically a through-bore through the hull of the second (aft) buoyant body 8, thus allowing the free flow or fluid through the recess 10, this is not required. For example, the recess may be closed ended, or a mesh, net, or grid may be provided at the upper surface of the second buoyant body 16 which covers the open end of the recess 10, such that fluid (e.g. air and/or liquid, e.g. liquid water) may freely flow through the recess 10 but such that debris may not flow therethrough.

In some alternative embodiments, the first (fore) buoyant body 4 and/or the second (aft) buoyant body 8 may each be provided with more than one wave channel and/or more than one recess.

In some alternative embodiments, the first (fore) buoyant body 4 may be provided with a recess instead of (or in addition to) the recess 10 provided in the second (aft) buoyant body 8, in which case, the recess in the first (fore) buoyant body 4 is sized and shaped to receive and retain the wave channel 12 of the second (aft) buoyant body 8, i.e. when the hinged raft 1 is in the folded configuration or when the angle between the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 is small (e.g. between 0° and 20°). In further alternative embodiments, the lower (conformal) surface 18 of the first (fore) buoyant body 4 and the lower (conformal) surface 20 of the second (aft) buoyant body 8 are not flat but are conformal with each other such that they can be brought into close mechanical contact with each other. For example, the lower (conformal) surface 18 of the first (fore) buoyant body 4 may be curved and concave, and the lower (conformal) surface 20 of the second (aft) buoyant body 8 may be correspondingly curved but convex. The lower conformal surfaces may have other conforming surface profiles.

Other embodiments can be envisaged by those skilled in the art from this application.

List of reference numerals

1. Wave energy convertor

2. Wave channel of first buoyant body 4. First (e.g. fore) buoyant body

6. Hinge

8. Second (e.g. aft) buoyant body

9. Still water surface

10. Recess

12. Wave channel of second buoyant body

14. Upper surface of first buoyant body

16. Upper surface of second buoyant body

18. Lower (conformal) surface of first buoyant body

20. Lower (conformal) surface of second buoyant body

22. Shipping container

24. Sloping base of wave channel of second buoyant body 26. End wall of wave channel of second buoyant body 28. Side wall of second buoyant body

30. Side wall of second buoyant body

32. Second end of wave channel of second buoyant body

31. First end of wave channel of second buoyant body

Claims

1. A hinged raft for a wave energy conversion device (WEC) comprising: a first elongate buoyant body; and a second elongate buoyant body, wherein the first and second elongate buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other, about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an elongate object having the hinge joint at one end.

2. A hinged raft according to claim 1 , where wherein the range of rotation of the first and second bodies via the hinge joint is sufficiently great that at least part of the at least one of the outer surfaces of the first body can be brought into contact with at least part of at least one of the outer surfaces of the second body.

3. A hinged raft according to claim 1 or claim 2, wherein when the raft is in the folded configuration the first and second bodies at least partially overlap with each other.

4. A hinged raft according to any one preceding claim, wherein when the raft is in the open configuration, the first and second bodies are in one of a range of positions in which a component of the direction in which the first body extends away from the hinge joint is opposite to a component of the direction in which the second body extends away from the hinge joint.

5. A hinged raft according to any one preceding claim, wherein the first elongate buoyant body comprises a wave receiving channel, the wave receiving channel having a wave receiving opening and wherein the second elongate buoyant body comprises a wave receiving channel, the wave receiving channel having a wave receiving opening.

6. A hinged raft according to any one preceding claim wherein at least part of at least one of the lower surfaces of the first body is conformal to at least part of at least one of the lower surfaces of the second body.

7. A hinged raft according to any one preceding claim wherein at least part of at least one of each of the lower surfaces of the first and second bodies has a peak-to-peak flatness of less than 5 cm.

8. A hinged raft according to any one preceding claim, wherein the first buoyant body comprises a recess and at least a portion of the second buoyant body extends into the recess of the first buoyant body, optionally when the hinged raft is in the folded configuration.

9. A hinged raft according to any one preceding claim, wherein the hinge joint is coupled to a power take off (PTO) system.

10. A hinged raft according to any one of claims 5 to 9, wherein the wave receiving channel of the first buoyant body comprises a sloping base and/or wherein the wave receiving channel of the second buoyant body comprises a sloping base.

11. A hinged raft according to any one of claims 5 to 10, wherein at least a portion of the wave receiving opening is provided at an end of the wave receiving channel.

12. A hinged raft according to any one of claims 10 to 11, wherein the said wave receiving channel has one or more channel resonant modes, the excitation of the one or more channel resonant modes being caused by excitation of the said wave receiving channel at one or more corresponding channel resonant frequencies, the one or more channel resonant frequencies being at least partly defined by the sloping base.

13. Apparatus comprising a container, the container retaining a hinged raft according to any one preceding claim.

14. Apparatus according to claim 13, wherein the hinged raft is in the folded configuration.

15. Apparatus according to claim 13 or claim 14, wherein the container is a shipping container.

16. A kit comprising a shipping container, the shipping container retaining a hinged raft according to any one preceding claim, wherein the hinged raft is in the folded configuration.

17. A method of extracting wave energy, the method comprising, providing hinged raft for a wave energy conversion device (WEC) comprising: a first elongate buoyant body; and a second elongate buoyant body, wherein the first and second elongate buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other, about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an elongate shape having the hinge joint at one end, and introducing the raft into water in the open configuration, such that the motion of waves in the water causes rotational motion of the first and second buoyant bodies relative to each other around the hinge joint.

18. A method of installing a hinged raft for a wave energy conversion device, the method comprising, transporting a container to a predetermined location, the container retaining a hinged raft for a wave energy conversion device (WEC) comprising: a first elongate buoyant body; and a second elongate buoyant body, wherein the first and second elongate buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other, about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an elongate shape having the hinge joint at one end, wherein the hinged raft is in the folded configuration in the container; removing the hinged raft from the shipping container in the folded configuration; introducing the hinged raft into a body of water at the predetermined location; and causing the hinged raft to transition into the open configuration.

19. A method of installing a hinged raft for a wave energy conversion device (WEC) according to claim 18, causing the hinged raft to transition into the open configuration comprises, providing an impetus at the hinge joint to thereby cause the first and second elongate buoyant bodies to rotate around the hinge joint in opposite directions from each other.

20. The method according to claim 19 wherein the impetus at the hinge joint comprises a force applied to encourage sagging of the hinged raft.

21. A method of uninstalling a hinged raft for a WEC, the method comprising, transporting a container to a predetermined location wherein a hinged raft for a WEC is installed in a body of water, the WEC comprising: a first elongate buoyant body; and a second elongate buoyant body, wherein the first and second buoyant bodies are connected by a hinge joint for rotation of the bodies relative to each other about an axis; the hinged raft having a folded configuration and an open configuration, wherein, when the raft is in the folded configuration, the first and second bodies are folded back to form an object having the hinge joint at one end; causing the hinged raft to transition from the open configuration into the folded configuration; removing the hinged raft from the body of water at the predetermined location; and introducing the hinged raft into a shipping container in the folded configuration.