WO2022260521A1

WO2022260521A1 - Wave energy converter

Info

Publication number: WO2022260521A1
Application number: PCT/NL2022/050322
Authority: WO
Inventors: Johannes Jacobus Hubertus Paulides
Original assignee: Aewh B.V.
Priority date: 2021-06-10
Filing date: 2022-06-09
Publication date: 2022-12-15
Also published as: NL2028428B1; EP4352357A1

Abstract

The invention relates to a wave energy converter, comprising at least one moveable floating body; at least three connections, for connecting the floating body to a fixed or floating world, wherein first sides of the three connections engage at at least three separate locations on the floating body, and wherein second sides of the three connections engage, either directly or indirectly, on the fixed or floating world; and at least one energy converting unit, wherein the at least three connections allow the moveable floating body the freedom to move in at least one substantially vertical direction.

Description

Wave energy converter

The present invention relates to a wave energy converter for converting wave energy into usable energy.

In the present days it is becoming more and more important to find renewable sources of energy. Generating energy in a manner that is substantially free of pollutants is becoming increasingly important due to numerous reasons. First of all, due to the political decision-making, which has caused an increase of taxes on energy resources that are not environmentally friendly. However, another major aspect lays in the fact that the fossil fuel resources are draining, causing the need for different energy resources.

The amount of renewable energy resources is steadily increasing. The most common type of renewable energy resources are the wind and solar energy resources. Albeit offering a good alternative to fossil energy, solar and wind energy have great disadvantages too. One of the main concerns regarding these type of renewable energy sources is that they are only partially predictable. As the name suggest, they rely on the amount of hours of sun, and the intensity thereof, as well as on the amount of wind, and the magnitude thereof. Hence, in case of a very windy and sunny day there might be an enormous amount of renewable energy generated through the solar and wind energy farms. However, this also puts the energy grid under a lot of stress. On the other hand, on a cloudy day with little to none wind, there might be a shortage of energy due to the demand exceeding the amount that is generated. Another disadvantage is that these energy resources are highly polluting the landscape. Wind turbines for example deliver the most energy when rising high above the landscape due to buildings disturbing the flow of air close to the ground. However, placing a lot of these wind turbines will be contributing to a pollution of the view, which is not desired to maintain a good ecosystem.

Contrary to the solar and wind energy, wave energy is known to be more constant. Additionally, wave energy typically is anticyclic. This holds that during times only relatively low amounts of energy may be harvested via solar and/or wind energy, wave energy is superfluous. Therefore, wave energy proves to be a highly potential contributor to the energy transition. It is known that wave energy could potentially supply a vast amount of the world’s energy requirements. However, currently known wave energy systems only convert the wave energy with limited efficiently.

An example of a wave energy converter is described in the international patent publication WO 2016111460 A1 . Here, movement of the cables is transformed into electrical energy. A downside of this publication is that relatively long cables are required which run along the bottom of the sea bed. This may also harm the marine life. Moreover, said device would not allow for extraction from the water surface during high waves, considering waves of a certain height, hit or pass by the floating body that is considered too heigh for the structure to handle. This may cause damage to the device, which is not desirable. Another example is shown in the German patent publication DE 102017009309 A1 . This document shows a wave energy converter which is limited to converting an energy induced by the wave height to the floating body into electrical energy. Rotational energy of the wave as such, that is the semi-circular or semi-elliptical movement of the wave, is not fully harvested.

It is thus a goal of the present invention to provide a system that is capable of converting the wave energy more efficiently.

It is a second goal of the present invention to provide for a system which allows to retrieve a higher amount of energy from a wave, or plurality of waves.

The present invention thereto proposes a wave energy converter, comprising at least one moveable floating body, at least three connections, for connecting the floating body to a fixed or floating world, wherein first sides of the three connections engage at at least three separate locations on the floating body, and wherein second sides of the three connections engage, either directly or indirectly, on the fixed or floating world, and at least one energy converting unit, for converting movement of the floating body into usable energy, preferably electrical energy, wherein the at least three connections allow the moveable floating body the freedom to move in at least one substantially vertical direction.

Due to the at least three connections engaging at at least three separate locations on the floating body the present invention may be able to extract more energy out of the waves. Therefore, the present invention is able to harvest more energy from the waves, and making it able to convert energy in a more efficient way compared to the prior art. Where in the present application reference is made to waves, in particular the movement of heave and surge of the waves and surface currents are meant. That is, the tide defines a base level of the water surface, and the waves define an amplitude along this base line. That is, the surface currents define a base mainly horizontal movement of the water, and the waves define an additional horizontal and vertical amplitude variation along this base line. The present invention in particular addresses the conversion of these waves that define the amplitude along the base level, hence the actual waves, and not the tidal fluctuations. The present invention in particular addresses also aims to compensate the surface currents with passive and/or active elements, hence the conversion of the waves that define the amplitude along the base level. It is known that a water particle near the water surface will make an orbiting movement when exposed to a single wave. The closer the water particle is situated towards the water surface, the larger the orbit of said motion will be. Therefore, in order to convert the most energy, a floating body may be used. On one side, the floating body is connected to a fixed or floating world, with respect to which fixed or floating world the floating body will move. The floating body is connected to the fixed or floating world by means of the at least three connections, wherein the at least three connections are situated such that the floating body is allowed to at least move in a substantially vertical direction, wherein said vertical movement is induced by the waves. The at least vertical movement is converted into usable energy by the at least one energy converting unit. During the at least vertical movement, also energy might be supplied to the floating device connected to the fixed or floating world by the at least three connections in order to ensure that the floating device is returning to a starting position that remains similar with respect to the fixed or floating world. The net usable energy may for example be electrical energy, however, the movement may also be converted into a movement that drives a different apparatus. During the harvesting both positive and negative energy can be extracted, this may compensate for surface currents, non-returning waves, especially applicable in shallower water, or when a foreign object is detected too late and extraction from the water surface is not possible anymore. In the last case the floating device can also be pushed under the water surface. Preferably, at least one connection is a substantially rigid connection. More preferably, all connections are substantially rigid. It is conceivable that at least one connection is at least partially formed by a active suspension system, preferably an electromagnetic active suspension system. Preferably, said active suspension is connected, directly or indirectly, to the fixed and/or floating world (or intermediate platform, if applied), and connected to the at least one floating body. The suspension as such may comprise a spring, such as a coil spring, a slidable pin, preferably slidable in the longitudinal direction of the suspension, one or more magnets, preferably actuatable magnets, and a bearing, such as a sliding bearing. Said magnets are preferably actuatable by, such that the amount of damping can be set to a preferred level. It is imaginable that said magnets are controllable by means of at least one controller. Said controller may co-act with at least one sensor, such as a camera for detecting foreign objects in a surrounding of the at least one floating body. The controller may adjust the position of the floating body of a foreign object is moving towards the at least one floating body, to prevent collisions. Such an active

The at least three (or at least six, if applied) connections may mutually form a power transmission. That is, the connections allow the power present in a wave to be transmitted to the energy conversion unit. The connections are preferably directly connected to the at least one movable floating body. In this respect, additional coupling elements, such as in particular wires or cables, are not required. Wires or cables in particular are not preferred, since they may add a low stiffness to the energy converting device which would not allow the higher harmonics that are on top of the fundamental waveshape to be harvested.

Preferably the at least three connections allow the movable floating body the freedom to move in at least one substantially vertical direction, and/or one substantially horizontal direction, and/or a substantially rotational direction, and/or a substantially spherical direction, and/or any substantial combination of vertical and horizontal direction. It is in particular beneficial when the connections allow the floating body to move in any of the aforementioned directions, since this furthermore increases the operational efficiency of the wave energy converter according to the present invention. As a non-limitative example, when the at least three connections allow at least one substantially horizontal and at least one substantially vertical movement of the floating body, the theoretical rotational orbit of the wave may be accurately followed by the floating body. As such, the wave energy converter is able to not only extract movement of the wave energy that is present in the vertical movement of the wave, but additionally is able to extract the energy in the horizontal movement of the wave. Thereby increasing the efficiency of wave energy conversion. Further the floating device may be returned to its initial position either by passive or active means. However, it may also be preferred that the at least three connections allow a pitching movement of the floatable body, wherein said pitch may be defined as the rotation of the floatable body with respect to its idle position or with respect to the fixed or floating world. Since waves may mutually be different in terms of height and width, which may also be expressed as amplitude and wave length, also elliptical or spherical movements of the floating body may be allowed by the at least three connections.

A single leg either one of three or an additional leg can be used to counteract the current that might be apparent in the sea so that this does not have to be compensated by the active legs. Theoretically, particles in a volume of water (e.g., in the sea or ocean) make a circular and/or ovular movement. This movement is induced by waves passing by. However, floating bodies, floating on a water surface level does not exactly follow the movement of a water particle in a surface region of the sea or ocean. That is, a floating body, such as a buoy or the floating body of the present invention will drift. The floating body will in particular drift in the travel direction of the waves. This effect may cause the floating body to drift to a spot wherein the movement is party restricted since one of the at least three connections, for example, is at maximum extension. That is, preferably, the at least one floating body returns to its initial position after a wave has passed. The at least one floating body is substantially freely suspended via the at least three connections, such that the at least one floating body is allowed to, in operational condition, essentially freely move over the water surface level. This allows the at least one floating body to be freely moved by a wave passing by. To this end, the wave energy converter further comprises at least one floating body retraction system, said floating body retraction system connected to the fixed or floating world, and to the at least one floating body, said floating body retraction system configured for moving the at least one floating body from a drifted position to a predetermined initial position. Said initial position being close to the position of the floating body before a wave has arrived or the position wherein the floating body is initially deployed. Preferably, said floating body retraction system uses a portion of the energy retracted from the wave to retract and/or reposition the floating body to its initial position.

It is preferred, during harvesting cycles from waves, considering a connection to a fixed or floating world, is that during at least a part of the cycle the at least one floating device is returned to its initial starting position. By connecting a floating body from underneath the water surface to a energy converting unit, this would require high energy since resistance by the water has to be overcome. In particular in case, in the present invention, the connections are connected to the floating body at a side facing away from the water surface, these may assist in retracting the floating body to its initial position.

During the repositioning it could be possible that the floating body has a preferred direction of movement in at least a substantially vertical direction, and/or one substantially horizontal direction, and/or a substantially rotational direction, and/or a substantially spherical direction, and/or any substantial combination of rotational, spherical, vertical and horizontal direction or alters its mass, or position with respect to the water in order to minimize the water drag the floating device will be subject to during this repositioning part of the net energy harvesting cycle, to be more specific with net we mean that the harvesting energy is usually higher compared to the supplied energy. Floating body trajectory optimization is therefore an great contribution to the efficacy and survivability of these wave energy extraction devices as described in this patent.

Such a floating body retraction system may for example be embodied by at least one of; an activating action from at least one of the at least three connections, at least one spring or elastic belt and/or rope. Preferably, wherein said spring or elastic belt is attached to the fixed or floating world. For clarity, the fixed or floating world can be above, below, or in the water and does not necessarily have to be the same fixed or floating world to whom the connections are attached. Additionally the position of the one activating action from said at least one of the at least three connection, one spring or elastic belt and/or rope is also to be altered in position to the floating body, for example, to the main direction of the waves or wind or surface currents, or any combination of waves, wind and surface currents by a connection that is also attached to the fixed or floating world. Preferably the length, variable or fixed stiffness and/or any combination of length and stiffness of the spring is such that substantially no forces are exerted by the spring onto the floating body when in its initial position. This may in particular be in case of negligence surface wind or surface currents, otherwise also forces will be exerted on the floating body in its initial position to hold, or return to, the initial position. And wherein the fixed or variable spring stiffness, or active element, is such that when the floating body drifts from its initial position, the spring retracts the floating body back to its initial position. The spring stiffness should however not exert a force on the floating body that exceeds the forces exerted onto the floating body by the waves, surface currents, surface wind and/or any other external force to might be acting of the floating body, at least during normal operating conditions. The forces exerted onto the floating body under normal operating conditions (e.g., when waves are present but preferably no storm) are in the range of 500N - 5000, 000N. It is also conceivable that a plurality of springs is used for retracting the floating body to its initial position. Preferably, the at least three springs are at a mutual angle of about 120 degrees, plus or minus 30 degrees. It is also conceivable that a plurality of springs or passive or active connections and/or any combination of springs and passive or active connections are used for retracting the floating body to its initial position. When the spring is positioned within the fixed or floating world, hence not an construction outside of the fixed or floating world to which the at least one active connection is positioned, at least three passive or active or any combination of active and passive components are at a mutual angle of about 120 degrees, plus or minus 30 degrees, attached to at least one floating body. As such, the floating body or bodies may be retracted to its initial position independent of the drift direction.

As an example, at least one winch, which may be an active connection, is used for pulling back or retracting the floating body to its initial position. Preferably, wherein a winch body is connected to the fixed or floating world and to the floating body, and wherein a winch cable end is either connected to the fixed or floating world or the floating body. Preferably, energy that is harvested by the wave energy converted is at least partially utilized for providing the winch with power to retract the floating body. It is also conceivable to provide a plurality of winches, such as three winches. By using a winch it is possible to not obstruct the floating body movement, and only exert a force during the retracting movement, i.e. winching, the floating body. Also the winches could be used to alter the floating body position within the water so as to minimize the energy required to return the floating body to its initial position. In this respect, it is preferred that the winch body is mounted to the fixed or floating world, and/or an intermediate platform as described in this application. The winch cable is preferably connected to a part of the floating body. The opposite mounting is however also possible. When the floating body comprises a plurality of floating bodies, such as three buoys, it is preferred that three winches are provided, wherein each winch cable is connected to a different floating body, in particular buoy, or if applied a connecting portion between said buoys. It is also imaginable that the winch is used for retracting the floating body from the water surface to a raised position. The winches could also be attached to a floating platform that is positioned below the floating body to increase, locally, the wave height by altering the depth the local water particles experience. This floating platform could also be used as a lid to completely or partially protect the connection from destructive elements, such as extreme waves, floating containers, sea life, or any other threatening devices within the water. For example, in combination with vision these threats will be identified and a control algorithm will be present to decide which action to take. Preferably, said winch is mounted to the fixed or floating world and/or an intermediate platform, if applied. This may allow to protect the wave energy converter to be protected in case of a storm, or when waves are too high and may cause damage to the system. Yet another alternative is to embody the floating body retraction system by means of electrical coils or magnets, preferably an actuatable magnet.

Optionally, the at least one floating body may be rotated during a pulling back movement of the floating body retraction system. That is, the floating body may have a predetermined shape, wherein said shape may induce a higher resistance when pulled over the water surface in a certain orientation. As such, rotating the floating body into an orientation to reduce pulling resistance in the water may increase energy efficiency of the energy converter. For example, an oval or rectangular shaped floating body will have more friction when pulling it through the water when the longitudinal axis of the floating body is perpendicular to the pulling direction as compared to when the longitudinal axis of the floating body is substantially parallel to the pulling direction. As such. Less energy is required by the floating body retraction system for pulling back the floating body to its initial position.

In another embodiment according to the present invention the at least one energy converting unit is configured for converting a rotational wave energy that is followed by the movable floating body. Where rotational wave energy is mentioned, this may be understood as the orbiting movement of a particle of water induced by a wave. The rotational wave energy is converted by the converting unit since the at least three connections allow the floating body to follow the movement of a wave, moving said floating body with respect to the fixed or floating world. The converting unit is in particular configured for converting the movement of the floating body, such as for example by means of a generator that converts the movement into usable, preferably electrical, energy. Preferably, at least one of the at least three connections is formed by a robot manipulator and/or robotic arm, preferably a six degrees of freedom robot manipulator. Preferably each of the at least three connections is formed by a robot manipulator and/or robotic arm, in particular a six degrees of freedom robot manipulator. A base side or shoulder of the at least one robot manipulator may be mounted or connected to the fixed or floating world and/or the intermediate platform, if applied. Preferably the effector of the robot manipulator and/or robotic arm is mounted and/or connected directly or indirectly at at least three different locations of the floating body. Preferably, each robot manipulator and/or robotic arm comprises a base, a first arm connected to said base, the base being rotatable around a first axis, the first arm rotatable around a second axis. Furthermore, a second arm may be connected to the first arm, wherein the second arm is rotatable around a third axis. An end effector may be attached to the second arm, wherein the end effector is rotatable around a fourth axis and/or a fifth axis. The first and second axis preferably being perpendicular to each other, the second and third axis being substantially parallel, and wherein the fourth axis is perpendicular to the third axis. The fifth axis is as such perpendicular to the fourth axis. It is also imaginable that more arms and axis are provided. It is preferred that each axis comprises a generating or regenerating motor, for converting the movement induced by the floating body into usable energy, preferably electric energy. The robot manipulator and/or robotic arm may also form the floating body retraction system. That is, using a part of the energy recovered from the movement of the floating body to retract the floating body to its initial position by driving said motors in the joints of the robotic arm. It is preferred that the wave energy converter comprises at least six connections, for connecting the floating body to a fixed or floating world, wherein a first sides of the six connections engage at at least three separate locations on the floating body, and wherein second sides of the six connections engage, either directly or indirectly, on the fixed or floating world. Preferably, the connections engaging at at least three separate locations on the floating body at a side of the floating body facing away from the water surface. Preferably, the at least six connections together forming a hexapod platform, in particular a six degree of freedom motion platform. This allows the movable floating body to have a bigger range of possible positions. Due to the increase of connections not only the freedom of motion of the floatable may be increased, also the structural integrity of the system as a whole may be improved. This is especially beneficial in terms of rough weather situations. During rough weather, such as for example wind speeds exceeding scale 8 of the Beaufort scale, hence wind speeds of 75 km/h and above, the forces exerted to the wave energy converter may be very large. During such conditions the at least six connections may be able to handle the forces induced by the weather better. To this end a hexapod connection is beneficial since this construction allows a wide range of movements, which makes it especially suitable for the present invention.

In yet a different embodiment it is conceivable that the wave energy converter comprises a plurality of floating bodies.

Preferably, the second sides of the six connections engage at at least three separate locations on a first side of an intermediate platform, preferably at at least six separate locations on a first side of an intermediate platform. It is also conceivable that the wave energy converter comprises an intermediate platform, wherein a first side of the at least three connections, for connecting the floating body to a fixed or floating world, engage at at least three separate locations on the floating body, and wherein second sides of the at least three connections engage, either directly or indirectly, on at least three separate locations on a first side of said intermediate platform said intermediate platform. The intermediate platform may, when directly or indirectly connected to the fixed or floating world, as such be part of the fixed or floating world. Hence, also when the intermediate platform is movably connected to the fixed or floating world, e.g. via a connecting arm when applied, said intermediate platform may be considered part of the fixed or floating world. The intermediate platform is preferably kept in a fixed or floating position. The floating body thus moves with respect to the intermediate platform via the at least three connections. More in particular if the intermediate platform, at a side facing away from the six (or three if only three connections are applied) connections, is movable connected to the fixed or floating world by means of at least one connecting arm. This allows for a more easy placement of the wave energy converter according to the present invention. Also, in case the connecting arm is movable, this allows for gradual adjustment of the level at which the intermediate platform is situated with respect to the water surface. As such, the wave energy converter according to the present invention is not negatively affected by a change in tide. Preferably the connecting arm is automatically adjusted according to the actual tide level, such that the wave energy converter is able to have a maximum efficacy at all times. That is especially due to the fact that placing the intermediate platform in accordance with the actual tide level, allows the floating body to make the biggest possible movements, which on its turn cause the most energy to be converted into usable energy. It is furthermore conceivable that the intermediate platform is provided with at least one connecting portion, which connecting portion is configured to engage with a locking portion of a different intermediate platform. As such, multiple intermediate platforms may be mutually releasably connected. To this end, it is preferred that each of the intermediate platforms is attached rigidly to the fixed or floating world with a connecting arm, or wherein one intermediate platform is connected to the fixed or floating world by such a connecting arm, and wherein the other intermediate platform is rigidly attached to said intermediate platform. Since movable floating body of the wave energy converter according to the present invention is suspended from a side facing away from the water surface, the wave energy converter does not negatively affect the marine live. In general it is also conceivable that the movable floating body or another portion of the wave energy converter, comprises at least one connector, for removably connecting the movable floating body, or another portion of the wave energy converter, to the movable floating body, or another portion, of an adjacent wave energy converter. The aforementioned embodiments comprising the intermediate platform and/or connecting arm may also be applied when only three connections are present.

In a different embodiment according to the present invention the at least one connecting arm is a driven connecting arm, for positioning the floating body with respect to the water surface. Preferably, the floating body is movable between an inactive position wherein the floating body is fully retracted from the water surface, and an active position wherein the floating boy is floating on the water surface. This is in particular convenient in order to prevent the wave energy converter from being damaged by rough sea conditions. Particularly when the wind speeds exceed scale 10 of the Beaufort scales, it could be desirable that the system can be fully retracted from the water surface. That is, moving the system, in particular the movable floating body, into a position wherein it is not or just partially floating on the water surface, preferably to a height wherein the system is not affected by the water at all. The system may for example be moved by winches and/or rack-pinion construction. Preferably the entire wave energy converter is rotated out of the water, such that the side that is normally in contact with the water surface is facing at least partially away from the water surface is the inactive position. It is also conceivable that the system is fully submersed into deeper water levels, where the sea is normally calmer.

In a different embodiment the wave energy converter further comprises a wave energy regulating element, such as a plate like structure, said wave energy regulating element locally changing the dimension, in particular the depth, of the water column situated under the movable floating body. This plate might be rectangular and straight, but could also have a variety of form, for example be round, a ball or balloon like shape, a marine like shape, and could even be of flexible shape, form and/or thickness. The wave energy regulating element is connected to the wave energy converter in such a way that it regulates the depth of the sea locally, formed by e.g. a plate, for example one or two meters below the water surface in the location of the movable floating body. The wave energy regulating unit may cause the waves to locally increase in height, period and/or combination of height and period, causing the wave energy converter to generate more energy or be less susceptible to destructive forces. It is furthermore conceivable that the wave energy regulating unit is adapted continuously by a controlling unit, such as to optimize the wave energy regulating unit to cause a maximum wave height, period and/or combination of height and period. The controlling unit may control the wave energy regulating unit based on one or more sensors, such as for example a float sensor, optical sensor, vision, radar, or lidar, or data from forecasting bodies, like the KNMI, or even remote sensor data from, for example, satellites or data from other, preferably closely positioned, energy harvesting devices, this could also, for example, be from data originated from wind turbines.

In a different embodiment according to the present invention at least one of the horizontal or vertical movements is absorbed by at least one of the connections or the connecting arm. Preferably, at least one connection or the connecting arm comprises a linear generator or multi linkages with generators like a robot, for converting the absorbed movement into usable energy. When the present application speaks of absorbing the movement of the movable floating body by at least one connection or connecting arm, it is in particular meant that the movement of the movable floating body is not transmitted to the fixed or floating world, but is in fact the movement is absorbed by a generator, converting said movement into usable energy. Ideally the type of generator that could be used is a linear generator, which could be positioned inside a connection, or in fact forming said connection. It is also conceivable that all the connections are formed by, or comprising, such a linear generator. Alternatively, it is also possible that the wave energy converter comprises a linear to rotary movement converter, for converting the substantially linear movements of the movable floating body into rotary movements, wherein said rotary movements are converted by a general generator. It is possible that, in case a linear type generator is used, that the translator, e.g. the moving portion of the linear generator, protrudes through the intermediate platform, such that the movement of the translator is not limited by the physical obstruction of the intermediate platform. To this end, the intermediate platform may be provided with through holes through which the translator of the linear generator may extend.

It is furthermore conceivable that the linear generator is connected to the fixed or floating world on one side, and to the intermediate platform on the other side. This allows the linear generator to be situated further away from the wave surfaces, which could prevent water from damaging the generator. If instead of, or in addition to, the linear generator, a linear to rotary movement converter is used with a complementary standard generator, they may also be attached in a similar fashion as described in this embodiment. In a different embodiment the linear generator may be connected to the side of the floating body facing away from the water surface on one side, and to the intermediate platform or fixed or floating world on the other side. As such the generator is placed directly where the movement is induced, which may result in less movement being dissipated, e.g. by means of transmission of said movement which cannot go without losses, and hence may convert the most amount of movement into usable energy.

Preferably, the at least one horizontal direction is the sway and/or surge direction, and wherein the at least one vertical direction is the heave direction. These movements may occur in any combination thereof, wherein combinations of these movements might cause a yaw, a pitch, or a roll motion to be introduced to the movable floating body, which movements are also allowed by the at least three connections.

The wave energy converter according to the present invention is attached to a fixed or floating world, the fixed or floating world is chosen from a group consisting of; a wind turbine, a drill platform, an oil-rig, a sea platform, a ship, a floating platform, a pillar, a barge, a breakwater, a jetty, a seawall, a mole, a groyne, a shore connection, a pier. The versatility enables the wave energy converter to be widely deployable, either in single format, wherein only a single wave energy converter is attached to such a fixed or floating world, or in a format wherein a plurality of interconnected wave energy converters mutually form a wave energy conversion harvest field. The latter especially being interesting in terms of off-shore wind turbine fields, wherein use can be made of the existing infrastructure to transport the converted energy to the shore or stored locally, or in close proximity to, in an energy storage device or for hydrogen production, for example using electrolysis.

The floating world is preferred to be substantially stable on a water surface. That is, the floating world should be able to provide for a substantially stable point of origin with respect to the at least one floating body for supporting the wave energy converter according to the invention, and preferably to provide for a frame of reference for said wave energy converter. At least, the mass moment of inertia of the fixed or floating world should be significantly larger compared to that of the moveable floating body. However, the inverse may also be possible, as such the moveable floating body will as such form the point of origin. Yet, the present invention is not limited thereto, it is also conceivable that the fixed world and the moveable floating body both move, wherein the at least three connections are configured for following respective movement between the fixed world and the floating body, such as to allow movements to be converted into usable energy.

Preferably, the floating body comprises at least one buoy, preferably at least three separated buoys, wherein said separated buoys are mutually connected. In case three separate buoys are used, the connections between said buoys may also be a semi-flexible connection, allowing the three buoys to independently make the mentioned horizontal, vertical and/or any combination movements. The buoy, or buoys may be of any kind of shape. Preferably the shape is adapted according to the types of waves in the location where the wave energy converter will be deployed. That is, locations where the waves are generally between 0.1 m and 1 m may require a different shape of buoy compared to locations where the waves are typically between 1 m and 5 m. It is also conceivable to deploy a boat shaped buoy, since it is known that a boat shape will its longitudinal direction in line with the local water current, which may be beneficial to effectively transmit the most amount of movement from the waves to the converting unit. Also a barbell shaped floating body could be beneficial to pull the buoy down in case the water particles are lowering so as to assist gravity and enlarge the virtual added mass, hence both the force and speed of the floating device. Typically, the radius of the at least one buoy, or the mutual distance between the center of at least two buoys, is between 0.5 and 20 m. It is conceivable that at least one of the connections comprises a spring and/or damper and/or hydraulic solution and/or a combination of the equivalent of such devices, for example an inverter. These might be use to increase, or temporarily either hydraulically mechanically or any other means store, the energy of the wave. That is, the spring may for example be used in order to increase rotational movement of the buoy, which additional movement increases the efficiency of the wave energy converter. To this end it is also possible that at least one of the at least three connection is an actively driven connection. Even though actively driving a connection can require energy, or creates additional energy, this might be used to for example increase rotation of the movable floating body, in particular in the case when a general converter is used, which converts rotational energy into electrical energy, then it might be more efficient to actively drive one connection in order to for example eliminate the usage of a linear to rotational movement converter, which may increase the efficiency of the converter as a whole. In another measure for increasing the energy generation the movable floating body, or at least a part thereof, is hollow, wherein said hollow space comprises a moving fluid, or masses that can change their position, for example roll, that can be actively pumped and/or varied, and or moving or completely sprung mass, to enhance the energy that can be extracted of the said floating body. It might even be that this fluid, or moveable mass, is moved from at least one floating device to another floating body or interchanged from the fixed or floating world to at least a floating device.

It is also conceivable that the at least one floating body comprises a plurality of buoys. At least two, preferably all of said plurality of buoys mutually connected. Said buoys may be connected in a predefined pattern, such as a matrix formation, a square formation, a circular formation, a triangular formation, or a combination thereof. The floating body comprising a plurality of buoys that are mutually connected may allow for increasing the diameter, effective area, or surface enclosed by, said floating body. This allows the floating body to be rotated through the peaks and valleys of waves, which rotational energy may also be converted by the energy converting unit.

Preferably, the wave energy converter comprises at least one sensor, such as a Lidar, infrared, sonar, or RADAR, for checking the presence of boats, sea creatures, such as whales. This may allow the wave energy converter to anticipate to the presence of such vessels, or animals. Anticipating may be explained as e.g. retracting the system from the water, which might prevent the animals to hurt themselves, or prevent vessels such as a boat or floating container from hitting the wave energy converter. This also allows the wave energy converter to be used in narrow channels, where there is presence of waves to be converted into usable energy, but limited space. Such situations would require the system to not obstruct the cargo transport for example, which could be circumvented when a sensor is applied, allowing the wave energy converter to automatically allow these ships to pass by unobstructed.

Maintenance, cleaning and sea worthiness of the, at least one floating body may a challenge as marine life could attach to said floating body. It is envisaged that every couple of years the fixed or floating platform and floating device may be removed and optionally transported to the shore and or cleaned on location. To allow for this in an easier way, the wave energy converter may comprise a mooring location. Mooring may be a challenge for ships at wind turbines, therefore it is anticipated that the connections may also be used to reduce the force of mooring ships to the fixed or floating platform. It is conceivable that the wave energy devices according to the present invention may be attached to an energy platform. Said energy platform may either store the energy locally, for example using transportable batteries or the like, or the energy platform may transport the energy, preferably electrical energy, to the shore, or for example the energy is used locally to create green fuels, like hydrogen. However, the transportation may also be embodied by a phase change material, like molten salt, to store and transport the energy. Also steam could be created as this does not require pumping to be transported over relatively long distances, or even light could be utilized as an energy transportation means. Especially for floating platforms that will be placed in the deep sea, locally utilizing the energy will be a real future use, as countries that do not have a shore line still require energy, especially electrical energy.

The invention is further illustrated by means of the non-limitative set of clauses presented below.

1 . Wave energy converter, comprising:

- at least one moveable floating body;

- at least three connections, for connecting the floating body to a fixed or floating world, wherein first sides of the three connections engage at at least three separate locations on the floating body, and wherein second sides of the three connections engage, either directly or indirectly, on the fixed or floating world; and

- at least one energy converting unit, for converting movement of the floating body into usable energy, preferably electrical energy; wherein the at least three connections allow the moveable floating body the freedom to move in at least one substantially vertical direction.

2. Wave energy converter according to clause 1 , wherein the at least three connections allow the movable floating body the freedom to move in at at least one substantially vertical direction, and/or one substantially horizontal direction, and/or a substantially rotational direction, and/or a substantially spherical direction, and/or any substantial combination of vertical and horizontal direction.

3 Wave energy converter according to clause 2, wherein the at least one energy converting unit is configured for converting a rotational wave energy that is followed by the movable floating body.

4. Wave energy converter according to any of the preceding clauses, wherein the wave energy converter comprises at least six connections, for connecting the floating body to a fixed or floating world, wherein a first sides of the six connections engage at at least three separate locations on the floating body, and wherein second sides of the six connections engage, either directly or indirectly, on the fixed or floating world.

5. Wave energy converter according to clause 4, wherein the at least six connections together forming a hexapod platform, in particular a six degree of freedom motion platform.

6. Wave energy converter according to clause 4 or 5, wherein the second sides of the six connections engage at at least three separate locations on a first side of an intermediate platform, preferably at at least six separate locations on a first side of an intermediate platform.

7. Wave energy converter according to clause 6, wherein the intermediate platform, at a side facing away from the six connections, is movable connected to the fixed or floating world by means of at least one connecting arm.

8. Wave energy converter according to any of the preceding clauses, wherein the connections engaging at at least three separate locations on the floating body at a side of the floating body facing away from the water surface.

9. Wave energy converter according to any of the preceding clauses, wherein the at least one connecting arm is a driven connecting arm, for positioning the floating body with respect to the water surface. 10. Wave energy converter according to any of the preceding clauses, wherein the floating body is movable between an inactive position wherein the floating body is fully retracted from the water surface, and an active position wherein the floating boy is floating on the water surface.

11 . Wave energy converter according to any of the preceding clauses, wherein the wave energy converter further comprises a wave energy regulating element, such as a plate, said wave energy regulating element locally changing the dimension, in particular the depth, of the water column situated under the movable floating body.

12. Wave energy converter according to any of the preceding clauses, wherein at least one of the horizontal or vertical movements is absorbed by at least one of the connections or the connecting arm.

13. Wave energy converter according to any of the preceding clauses, wherein the at least one connection or connecting arm comprises a linear generator, for converting the absorbed movement into usable energy.

14. Wave energy converter according to clause 13, wherein the linear generator is connected to fixed or floating world on one side, and to the intermediate platform on the other side. 15. Wave energy converter according to clause 13 or 14, wherein the linear generator is connected to the side of the floating body facing away from the water surface on one side, and to the intermediate platform or fixed or floating world on the other side. 16. Wave energy converter according to any of the preceding clauses, wherein the at least one horizontal direction is the sway and/or surge direction, and wherein the at least one vertical direction is the heave direction. 17. Wave energy converter according to any of the preceding clauses, wherein the fixed or floating world is chosen from a group consisting of; wind turbine, drill platform, sea platform, ship, floating platform, shore connection, pier.

18. Wave energy converter according to any of the preceding clauses, wherein the floating body comprises at least one buoy, preferably at least three separated buoys, wherein said separated buoys are mutually connected.

19. Wave energy converter according to clause 18, wherein the radius of the at least one buoy, or the mutual distance between the center of at least two buoys, is between 1 and 20 m.

20. Wave energy converter according to any of the preceding clauses, wherein at least one of the connections comprises a spring and/or damper.

21 . Wave energy converter according to any of the preceding clauses, wherein at least one of the at least three connection is an actively driven connection.

22. Wave energy converter according to any of the preceding clauses, wherein the movable floating body comprises at least one connector, for removably connecting the movable floating body to the movable floating body of an adjacent wave energy converter.

23. Wave energy converter according to any of the preceding clauses, wherein the movable floating body, or at least a part thereof, is hollow, wherein said hollow space comprises a fluid that is free to move, moveable mass and/or fully sprung mass, for enhancing the movement of said floating body.

The present invention will hereinafter be further elucidated based on the following non-limitative drawings, wherein:

- figure 1 shows a schematical representation of a first embodiment according to the present invention; - figure 2 shows a schematical side view of an embodiment of the present invention; and

- figure 3 shows a representation of a second embodiment according to the present invention.

Figure 1 shows a non-limitative example of the wave energy converter 1 according to the present invention. The wave energy converter 1 is embodied with a movable floating body 2, wherein the movable floating body 2 is formed by three separate buoys 3, which buoys 3 are mutually connected by three beams 4. Together, the buoys 3 and the beams 4 form the movable floating body 2. The movable floating body is connected to a fixed or floating world 6. In this particular embodiment the fixed or floating world 6 is formed by the pillar 6 of a wind turbine. The movable floating body 2 is connected to the fixed or floating world by means of e hexapod structure, formed by six connections 5. The connections 5 engage on one side at three separate locations on the movable floating body 2, in particular one locations on each of the three buoys 3. On the other side the connections 5 engage at an intermediate platform 11 at six different locations. The intermediate platform 11 is on its turn connected to the pillar 6 of the wind turbine by means of a connecting arm 8. The connecting arm 8 allows the intermediate platform 11 to be positioned at a preferred distance with respect to the water surface 12. To this end, a winch system 9, 10, allows to lift or drop the connecting arm in the desired location. Once it is in the right position, said position may be locked, such that the position of the intermediate platform 11 is fixed or floating with respect to the water surface. This allows the movable floating body 2 to follow the movement of the waves, and causes the connections 5 to move. The connections 5 comprise linear generators 7 which convert the movement into usable, in this case electrical energy. The linear generators 7 may for a part of the connections 5, but may also form the entire connection 5 as such.

Figure 2 shows a side view of the wave energy converter 1 of figure 1 wherein in particular the movement of the movable floating body 2 is depicted. The figure shows two waves, 13 a and 13b which are shifted with respect to each other. The direction of the waves is indicated by the arrow W. It is known that a particle P follows a particular orbital movement, wherein the orbital movement 14 diminishes as a function of depth. That is, the rotational movement of the particle P caused by the wave reduces in diameter, wherein the maximum diameter H is equal to the height H of the waves. The orbital movement 14 caused by the waves 13a, 13b, is also induced onto the buoy 3 of the movable floating body according to the present invention. The figure further depicts the intermediate platform 11 . The buoy 3 of the movable floating body 2 is depicted in four different positions along the orbital movement 14. These four positions are depicted to indicate the movement of the connections 5, showing possible positions of the connections 5. The linear generator 7 absorbs and converts the movement of the movable floating body 2 into electrical energy. To this end, a translator of the linear generator 7 may even extend through the intermediate platform, as indicated in the figure, to allow the linear generator 7 to extract the maximum amount of energy from the wave. That is, it allows the buoy 3 of the movable floating body 2 to follow substantially the entire vertical movement H of the wave. Figure 3 shows an alternative embodiment of a wave energy converter 20 according to the present invention that has a special connection which allows the wave energy converter 20 to convert more energy. Identical elements of the wave energy converter 20 and the wave energy converter 1 as shown in figures 1 and 2 are referred to with identical reference signs. The wave energy converter 20 is able to convert more of the energy that is present in the waves into usable energy than the wave energy converter 1 as shown in the previous figures. To this end, the connections 5 are movable connected to the buoys 3 of the floating body 2. In particular the connections 5 are connected to the buoy 3 by means of a ball-socket joints 17. These joints 17 allows the buoys to rotate around an axis 18 that is formed by the joints 17 and the respective buoy 3 they are connecting to. A similar type of joint 16 is used to allow a rotation of a buoy 3 with respect to the beam 4 that connects a buoy 3 to another buoy 3. Also indicated in this figure are the holes 15 that are provided in the intermediate platform 11 that allow the translators of the energy converting units 7 to extend through the platform to achieve more freedom of motion. To this end the stator magnet may be housed inside the connections 5.

Claims

1. Wave energy converter, comprising: - at least one moveable floating body;

2. Wave energy converter according to claim 1 , characterized in that the at least three connections allow the movable floating body the freedom to move in at at least one substantially vertical direction, and/or one substantially horizontal direction, and/or a substantially rotational direction, and/or a substantially spherical direction, and/or any substantial combination of vertical and horizontal direction.

3 Wave energy converter according to claim 2, characterized in that the at least one energy converting unit is configured for converting a rotational wave energy that is followed by the movable floating body.

4. Wave energy converter according to any of the preceding claims, characterized in that at least one of the at least three connections is a robot manipulator and/or a robotic arm, preferably comprising three degrees of freedom, preferably six degrees of freedom.

5. Wave energy converter according to any of the preceding claims, characterized in that the wave energy converter comprises at least six connections, for connecting the floating body to a fixed or floating world, wherein a first sides of the six connections engage at at least three separate locations on the floating body, and wherein second sides of the six connections engage, either directly or indirectly, on the fixed or floating world.

6. Wave energy converter according to claim 5, characterized in that the at least six connections together forming a hexapod platform, in particular a six degree of freedom motion platform.

7. Wave energy converter according to claim 5 or 6, characterized in that the second sides of the six connections engage at at least three separate locations on a first side of an intermediate platform, preferably at at least six separate locations on a first side of an intermediate platform.

8. Wave energy converter according to claim 7, characterized in that the intermediate platform, at a side facing away from the six connections, is movable connected to the fixed or floating world by means of at least one connecting arm.

9. Wave energy converter according to any of the preceding claims, characterized in that the connections engaging at at least three separate locations on the floating body engage at a side of the floating body facing away from the water surface.

10. Wave energy converter according to any of the preceding claims, characterized in that the at least one connecting arm is a driven connecting arm, for positioning the floating body with respect to the water surface.

11 . Wave energy converter according to any of the preceding claims, characterized in that the floating body is movable between an inactive position wherein the floating body is fully retracted from the water surface, and an active position wherein the floating boy is floating on the water surface.

12. Wave energy converter according to any of the preceding claims, characterized in that the wave energy converter further comprises a wave energy regulating element, such as a plate, said wave energy regulating element locally changing the dimension, in particular the depth, of the water column situated under the movable floating body.

13. Wave energy converter according to any of the preceding claims, characterized in that at least one of the horizontal or vertical movements is absorbed by at least one of the connections or the connecting arm.

14. Wave energy converter according to any of the preceding claims, characterized in that the at least one connection or connecting arm comprises a linear generator, for converting the absorbed movement into usable energy.

15. Wave energy converter according to claim 14, characterized in that the linear generator is connected to fixed or floating world on one side, and to the intermediate platform on the other side.

16. Wave energy converter according to claim 14 or 15, characterized in that the linear generator is connected to the side of the floating body facing away from the water surface on one side, and to the intermediate platform or fixed or floating world on the other side.

17. Wave energy converter according to any of the preceding claims, characterized in that the at least one horizontal direction is the sway and/or surge direction, and wherein the at least one vertical direction is the heave direction.

18. Wave energy converter according to any of the preceding claims, characterized in that the fixed or floating world is chosen from a group consisting of; wind turbine, drill platform, sea platform, ship, floating platform, shore connection, pier.

19. Wave energy converter according to any of the preceding claims, characterized in that the wave energy converter further comprises at least one floating body retraction system, said floating body retraction system connected to the fixed or floating world, and to the at least one floating body, said floating body retraction system configured for moving the at least one floating body from a drifted position to a predetermined initial position.

20. Wave energy converter according to claim 19, characterized in that the at least one floating body retraction system is at least partially formed by a winch, wherein a winch body is connected to the fixed or floating world or the floating body, and wherein a winch cable is connected to the fixed or floating world or the floating body.

21 . Wave energy converter according to claim 19 or 20, wherein at least a portion of the energy converted is used for powering the at least one floating body retraction system.

22. Wave energy converter according to any of the preceding claims, characterized in that the floating body comprises at least one buoy, preferably at least three separated buoys, wherein said separated buoys are mutually connected.

23. Wave energy converter according to claim 22, characterized in that the radius of the at least one buoy, or the mutual distance between the center of at least two buoys, is between 1 and 20 m.

24. Wave energy converter according to any of the preceding claims, characterized in that at least one of the connections comprises a spring and/or damper.

25. Wave energy converter according to any of the preceding claims, characterized in that at least one of the at least three connection is an actively driven connection.

26. Wave energy converter according to any of the preceding claims, characterized in that the movable floating body comprises at least one connector, for removably connecting the movable floating body to the movable floating body of an adjacent wave energy converter.

27. Wave energy converter according to any of the preceding claims, characterized in that the movable floating body, or at least a part thereof, is hollow, wherein said hollow space comprises a fluid that is free to move, moveable mass and/or fully sprung mass, for enhancing the movement of said floating body.