NL2028428B1

NL2028428B1 - Wave energy converter

Info

Publication number: NL2028428B1
Application number: NL2028428A
Authority: NL
Inventors: Jacobus Hubertus Paulides Johannes
Original assignee: Aewh B V
Priority date: 2021-06-10
Filing date: 2021-06-10
Publication date: 2022-12-20
Also published as: WO2022260521A1; 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 5 to a fixed 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 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 10 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. 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. it is thus a goal of the present invention to provide a system that is capable of converting the wave energy more efficiently.

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 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 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 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 world, with respect to which fixed world the floating body will move. The floating body is connected to the fixed 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. The usable energy may for example be electrical energy, however, the movement may also be converted into a movement that drives a different apparatus.

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. 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 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.

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 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. It is preferred that the wave energy converter comprises at least six connections, for connecting the floating body to a fixed 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 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. More in particular if the intermediate platform, at a side facing away from the six connections, is movable connected to the fixed 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 5 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 efficiency 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. lt 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 world with a connecting arm, or wherein one intermediate platform is connected to the fixed 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. 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 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, said wave energy regulating element locally changing the dimension, in particular the depth, of the water column situated under the movable floating body. 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, causing the wave energy converter to generate more energy. lt 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. The controlling unit may control the wave energy regulating unit based on one or more sensors, such as for example a float sensor.

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, 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 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 fixed 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 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 world, the fixed world is chosen from a group consisting of; a wind turbine, a drill platform, a sea platform, a ship, a floating platform, 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 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.

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 and/or vertical 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 5m. ltis 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. Typically, 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. lt is conceivable that at least one of the connections comprises a spring and/or damper. These might be use to increase 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, 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. 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.

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 world 6. In this particular embodiment the fixed world 6 is formed by the pillar 6 of a wind turbine.

The movable floating body 2 is connected to the fixed 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 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

Conclusions

CLAIMS 1. Wave energy converter, comprising: - at least one movable floating body; - at least three connections, for connecting the floating body to a fixed world, with first sides of the three connections engaging at least three separate locations of the floating body, and with second sides of the three connections engaging directly or indirectly with the fixed world; and - at least one energy conversion unit, for converting movement of the floating body into usable energy, preferably electrical energy, the at least three connections allowing at least one substantially vertical movement of the movable floating body.

Wave energy converter according to claim 1, characterized in that the at least three connections comprise at least one substantially vertical movement, and/or one substantially horizontal movement, and/or a substantially rotational movement, and/or in a substantially allow spherical movement, and/or any substantial combination of vertical and horizontal movement, of the movable buoyancy body

A wave energy converter according to claim 2, characterized in that the at least one energy conversion unit is configured to convert a rotating wave energy tracked by the movable floating body.

4. A wave energy converter according to any one of the preceding claims, characterized in that the wave energy converter comprises at least six connections for connecting the floating body to a fixed world, with first sides of the six connections engaging at least three separate locations. of the buoyancy body, and wherein second sides of the six connections engage directly or indirectly with the fixed world.

Wave energy converter according to claim 4, characterized in that the at least six connections together form a hexapod platform, in particular a motion platform with six degrees of freedom.

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

Wave energy converter according to claim 6, characterized in that the intermediate platform, on a side remote from the six connections, is movably connected to the fixed world by means of at least one connection arm.

8. Wave energy converter as claimed in any of the foregoing claims, characterized in that the connections act on at least three separate locations on the movable floating body on a side of the floating body remote from the water surface.

9. A wave energy converter according to any one of the preceding claims, characterized in that the at least one connecting arm is a driven connecting arm, for positioning the floating body relative to the water surface.

10. A wave energy converter according to any one of the preceding claims, characterized in that the floating body is movable between an inactive position, in which the floating body is substantially fully withdrawn from the water surface, and an active position, in which the floating body floats on the water surface.

A wave energy converter according to any one of the preceding claims, characterized in that the wave energy converter further comprises a wave energy control element, such as a plate, which wave energy control element locally determines the size, in particular the depth, of the water column located below the movable floating body. , changes.

A wave energy converter according to any one of the preceding claims, characterized in that at least one of the horizontal or vertical movements is absorbed by at least one of the links or link arm.

13. A wave energy converter according to any one of the preceding claims, characterized in that the at least one connection or connection arm comprises a linear generator for converting the captured motion into usable energy.

Wave energy converter according to claim 13, characterized in that the linear generator is connected to the fixed world on one side and to the intermediate platform on the other side.

15. Wave energy converter according to claim 13 or 14, characterized in that the linear generator is connected to the side of the floating body remote from the water surface on the one side and to the intermediate platform or fixed world on the other side.

A wave energy converter according to any one of the preceding claims, characterized in that the at least one horizontal movement is moving and/or startling, and wherein the at least one vertical movement is dipping.

A wave energy converter according to any one of the preceding claims, characterized in that the solid world is selected from the group consisting of; wind turbine, drilling platform, offshore platform, ship, floating platform, shore connection, pier.

Wave energy converter according to any one of the preceding claims, characterized in that the floating body comprises at least one buoy, preferably three separate buoys, said separate buoys being interconnected.

Wave energy converter according to claim 18, characterized in that the radius of the at least one buoy, or the mutual distance between the centers of two buoys, is between 1 m and 20 m.

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

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

22. A wave energy converter according to any one of the preceding claims, characterized in that the movable floating body comprises at least one coupling for releasably connecting the movable floating body to the movable floating body of an adjacent wave energy converter.

23. A wave energy converter according to any one of the preceding claims, characterized in that the movable floating body, or at least a part thereof, is hollow, the said hollow space comprising a freely movable liquid, movable mass and/or fully resilient mass, for amplifying the movement of said floating body.