Wave energy device

Abstract

The invention relates to a device for capturing wave energy, the device comprising a structure (1) that is intended, when in use, to float and to be anchored to a seabed, this structure comprising at least a first and a second wall (10, 11), the first and second walls being non-coplanar, one of the walls (10) comprising at least a first opening and a first flap (101) mounted inside the at least one first opening by being able to rotate about a first axis so as to be able to be moved rotationally about the first axis owing to the effect of the surge and produce, when in operation, mechanical energy, two adjacent walls of the structure being joined together via a float (12) to form a polygonal structure that has a bottom and an upper portion facing one another, the first flap being vertical in the rest position and behaving as a movable barrier which creates a pressure difference over the height of the flap so as to produce mechanical energy, the device also comprising means for converting the mechanical energy of the flaps into electrical energy.

Description

Wave energy device

[0001] The present invention falls within the general field of renewable energies and more particularly of the recovery of wave energy in electrical form.

[0002] More specifically, the invention is designed to also allow, in addition to the recovery of wave energy, the recovery of wind energy and / or solar thermal and / or photovoltaic energy.

[0003] Several wave energy devices have already been proposed.

[0004] Thus, document FR2981992 describes a wave energy recovery device which comprises several compartments filled with liquid. The swell creates a difference in liquid height between the compartments and a flow of liquid from one compartment to another, this flow driving a turbine.

[0005] This device is designed to float and can therefore be installed in the open sea.

[0006] However, it has the disadvantage of being of a complex design.

[0007] Documents EP3278662 and EP4071352 describe wave energy harvesting devices fixed on a platform and which comprise a float designed to float at the waterline of the platform. It performs an alternating rotation around an axis of rotation under the action of the waves so as to drive a crankshaft connected to hydraulic cylinders and generate electrical energy.

[0008] Document FR3102492 describes a wave attenuation device which also converts wave energy into electrical energy.

[0009] This device is intended, in operation, to be fixed to the seabed. It comprises a flap movable in rotation around an axis which extends vertically in its rest position and which can be moved in rotation in two opposite directions of rotation, on either side of a vertical median plane, under the effect of the swell. The device comprises a piston which is driven in translation by the rotation of the flap and which is associated with a valve for regulating the flow of hydraulic fluid displaced by the piston so as to drive a hydroelectric generator.

[0010] This device is very effective in attenuating swell, in particular thanks to the presence of a porous wall located downstream of the flap relative to the direction of swell propagation, but it is not designed specifically for energy recovery. Moreover, the fixed distance between the flap and the skirt necessarily limits this recovery.

[0011] Other systems are under development, including hybrid platforms designed to harvest wave energy and support wind turbines. Anchoring these platforms is complex and costly. They themselves must be oversized to withstand environmental conditions. Otherwise, they are not suitable for a very wide wave spectrum.

[0012] The invention aims to overcome these drawbacks by proposing a wave energy recovery device whose structure is simple, modular and robust and whose efficiency can be easily optimized. This device will subsequently be called a wave energy device.

[0013] Another object of the invention is to provide a wave energy device which can serve as a support structure for other energy recovery systems, such as wind turbines or photovoltaic panels.

[0014] To this end, an object of the invention is to provide a wave recovery device comprising a structure intended to float and to be anchored on a seabed, in use, this structure comprising at least a first and a second wall, the first and second walls being non-coplanar, one of them comprising at least a first opening and a first flap mounted inside said at least a first opening while being movable in rotation about a first axis, so as to be able to be moved in rotation about said first axis under the effect of the wave and to generate, in operation, mechanical energy, two adjacent walls of the structure being connected together by means of a float to form a polygonal structure having a bottom and an upper part facing each other,the first shutter being vertical in the rest position and behaving like a mobile barrier which creates a pressure difference over the height of the shutter to generate mechanical energy, the device also comprising means for converting the mechanical energy of the shutters into electrical energy.,

[0015] Throughout the description, the term vertical refers to a direction parallel to gravity, while the term horizontal refers to directions perpendicular to it.

[0016] According to particular embodiments:

[0017] The second wall of this wave recovery device comprises at least a second opening and a second flap mounted inside the second opening while being movable in rotation around a second axis.

[0018] The axis of a shutter of the present device is substantially parallel to said bottom.

[0019] The conversion means of the device according to the invention comprise, connected to each of the flaps of the structure, at least one piston driven in translation by said flap.

[0020] The bottom of the device according to the invention is partially closed.

[0021] The structure of the device according to the invention comprises at least three walls connected together so as to form an outer belt, said structure being closed.

[0022] At least one of said walls of the device according to the invention is solid.

[0023] Said structure comprises at least five walls connected to each other, at least four of them forming an outer belt and at least one of them being placed inside said belt.

[0024] The said structure supports at least one wind turbine and / or a photovoltaic power plant.

[0025] At least one float of said structure and / or at least one wall provided with a flap of said structure comprises(s) a widened box on the bottom side of said structure.

[0026] At least one of the flaps of said structure has a generally concave shape, the concavity being turned towards the interior of said structure.

[0027] Furthermore, a shutter has a density strictly greater than 1.

[0028] Other characteristics of the invention will be set out in the detailed description below, given with reference to the appended figures, given by way of example, and which represent respectively:

[0029] , a schematic top view of a first embodiment of a wave energy device according to the invention, the structure of which comprises two walls;

[0030] , a schematic front view of a wall of the wave energy device of the;

[0031] , a schematic top view of a second embodiment of a wave energy device according to the invention, comprising three walls arranged in a triangle;

[0032] , a schematic top view of a third embodiment of a wave energy device according to the invention, comprising nine walls forming a general triangular structure;

[0033] , a schematic top view of a fourth embodiment of a wave energy device according to the invention, comprising four walls arranged in a square;

[0034] , a schematic top view of a fifth embodiment of a wave energy device according to the invention, comprising nine walls forming a general hexagonal structure which supports wind turbines;

[0035] , a schematic side view along arrow VI of the device illustrated in ;

[0036] , a schematic perspective top view of a sixth embodiment of a wave energy device according to the invention, comprising twelve walls arranged in a polygon;

[0037] , a schematic view of the wave energy device illustrating the means of energy conversion;

[0038] ,

[0039] , And

[0040] illustrate, seen from the side, different variants of the shutter;

[0041] ,

[0042] ,

[0043] ,

[0044] ,

[0045] illustrate, seen from the side, different variants of the embodiment of the piston(s) of the energy conversion means;

[0046] , a schematic side view of a variant of the wall of the structure of a wave energy device according to the invention.

[0047] In the following, the same elements will be designated by the same reference numbers.

[0048] With reference to figures 1 and 2, in this first embodiment, the structure 1 of the wave energy device comprises two walls 10, 11 connected to each other by a float 12. These two walls form a non-zero angle between them or are non-coplanar.

[0049] In this example, the structure also comprises a float 13 fixed to the free end of the wall 10, opposite the float 12, as well as a float 14 fixed to the free end of the wall 11, opposite the float 12. This embodiment is preferred but these two floats 13 and 14 could nevertheless be omitted.

[0050] This structure therefore has a bottom 15 and an upper part 16. The latter can be open or closed. Furthermore, the bottom 15 is preferably partially closed, for example by plates (not shown in the figures). These plates have an anti-pounding effect.

[0051] The shutters and walls therefore extend vertically or substantially vertically when the structure is placed on a flat support.

[0052] The wall 10 has an opening 100, while the wall 11 is solid. In the opening 100 is mounted a flap 101, movable in rotation about an axis 102 which is in the plane of the wall 11, substantially parallel to the bottom of the structure or else substantially horizontal when the structure 1 is placed on a flat support. This orientation has the advantage of allowing the flap to be returned to its vertical rest position (or else in the plane of the wall), thanks to the action of gravity.

[0053] The structure is designed so that during operation the horizontal rotation axis is not submerged but rather above the structure's waterline.

[0054] The opening 100 here has a rectangular shape but other shapes can be considered, such as that illustrated in the.

[0055] The flap 101 here has the shape of a rectangular flat plate. Other shapes can be envisaged, in particular to take into account the shape of the opening of the plate. Furthermore, other profiles are illustrated in Figures 10 to 12.

[0056] Lamontre shows that the floats 12 and 13 are provided, on the side of the bottom 15, with a box 17, 18 whose section is wider than that of the floats and whose height is less than this section. Each box therefore widens the base of a float and contributes to reducing the heave effect. The invention is however not limited to this embodiment and these boxes could be omitted.

[0057] Illustrates a second embodiment in which the structure 2 of the wave energy device comprises three walls 20, 21, 22 connected to each other by three floats 23, 24, 25. These three walls are non-coplanar and form a non-zero angle between them, two by two. In this example, the walls are substantially identical, the structure 2 therefore has, seen from above, the shape of an equilateral triangle and this angle is 60°.

[0058] This structure 2 has a bottom and an upper part (not referenced in the figure).

[0059] The walls 20 and 21 each have an opening (not referenced in the figure), while the wall 22 is solid. In each of the openings is provided a flap 201, 211, movable in rotation about an axis (not referenced in the figure) which extends in the plane of the wall in which it is provided and which is substantially parallel to the bottom of the structure or else substantially horizontal when the structure 2 is placed on a flat support.

[0060] This structure forms an outer belt, that is, a closed structure, unlike structure 1 illustrated in which is an open structure. Therefore, as will be explained in more detail in the rest of the description, a resonance can be obtained inside this closed structure.

[0061] This second embodiment also includes variants. Thus, the wall 22 could include an opening provided with a shutter and / or be solid.

[0062] In the third embodiment illustrated in 1, the structure 3 of the wave energy device comprises nine walls 30 to 38 connected to each other by six floats 39a to 39f. These nine walls are non-coplanar and form a non-zero angle between them, two by two.

[0063] This structure 3 has a bottom and an upper part (not referenced in the figure).

[0064] The six walls 30 to 35 are connected to each other by all the floats so as to form an outer belt having the shape of a triangle. In this example, the walls are substantially identical and each face of the triangle has two walls, the outer belt therefore having, seen from above, the shape of an equilateral triangle and the structure 3 is closed.

[0065] Thus, the walls 30, 31, respectively 32, 33, respectively 34, 35 are coplanar. On the other hand, the walls 30, 31 make a non-zero angle with the walls 32, 33 and 34, 35 respectively. This angle is here 60°.

[0066] Each of the six walls 30 to 35 has an opening (not referenced in the figure) in which a flap 301 to 351 is mounted, movable in rotation around an axis (not referenced in the figure) which extends in the plane of the wall in which it is provided and which is substantially parallel to the bottom of the structure or else substantially horizontal when the structure 3 is placed on a flat support.

[0067] Inside this outer belt, the three other walls 36 to 38 are provided, which are connected to each other by means of the floats 39b, 39d and 39f. These three walls 36 to 38 are non-coplanar and form a non-zero angle between them, two by two. In this example, the walls are substantially identical, so, when viewed from above, they form an equilateral triangle, and this angle is 60°.

[0068] These three walls 36 to 38 are full.

[0069] This third embodiment also includes variants. Thus, one or more of the walls 36 to 38 could include an opening with or without a shutter and / or one or more of the walls 30 to 35 could be without a shutter or solid.

[0070] Illustrates a fourth embodiment in which the structure 4 of the wave energy device comprises four walls 40 to 43 connected to each other by four floats 44 to 47 so as to form an outer belt. These four walls are non-coplanar and form a non-zero angle between them, two by two. In this example, the walls are substantially identical, the structure 4 has, seen from above, the shape of a square and this angle is 90°. This is again a closed structure.

[0071] This structure 4 has a bottom and an upper part (not referenced in the figure).

[0072] Each of the facing walls 40 and 42 has an opening (not referenced in the figure) in which a flap 401 and 421 is mounted, movable in rotation around an axis (not referenced in the figure) which extends in the plane of the wall in which it is provided and which is substantially parallel to the bottom of the structure or else substantially horizontal when the structure 4 is placed on a flat support.

[0073] Each of the walls 41 and 43 opposite each other are solid.

[0074] This fourth embodiment also includes variants. Thus, one of the walls 40, 42 could be without a flap or solid. Furthermore, one of the walls 41, 43 or both could have an opening with or without a flap. Finally, another wall (not illustrated in the figure) could be fixed between the floats 45 and 47 and therefore be placed inside the outer belt.

[0075] Figures 6 and 7 illustrate a fifth embodiment in which the structure 5 of the wave energy device comprises ten walls 50 to 59 connected to each other by seven floats 60 to 66. These ten walls are non-coplanar and form a non-zero angle between them, two by two.

[0076] This structure 5 has a bottom 66 and an upper part 67. The six walls 50 to 55 are connected to each other by the floats 60 to 65 so as to form an outer belt having, seen from above, the shape of a regular hexagon, the walls being substantially identical. The internal angle between two adjacent walls of the outer belt is approximately 120°.

[0077] Inside this outer belt, the four other walls 56 to 59 are provided which are connected to each other via the float 66 and to the outer belt via one of the floats 60 to 65. The structure 5 is a closed structure. These four walls 56 to 59 are non-coplanar and form a non-zero angle between them, two by two. In this example, all the walls are substantially identical and the angle between two adjacent walls of the structure is 60°.

[0078] Each of the ten walls 50 to 59 has an opening. Only the openings 520 to 540 of the walls 52 to 54 and the rotation axes 522 to 542 of the flaps 521 to 541 are illustrated in the. In each opening, a flap 501 to 591 is mounted, movable in rotation about an axis (not referenced in the) which is substantially parallel to the bottom of the structure or substantially horizontal when the structure 5 is placed on a flat support. Each axis extends in the plane of the wall in which it is provided. Furthermore, the shows that the axes are located in the same substantially horizontal plane when the structure 5 is placed on a flat support.

[0079] The invention is however not limited to this embodiment and the axes could be located in different horizontal planes.

[0080] Lamontre shows that the floats 62 to 65 are provided, on the side of the bottom 60, with a box 62a to 65a whose section is wider than that of the floats and whose height is less than this section. Each box therefore widens the base of a float and contributes to reducing the heave effect. The invention is however not limited to this embodiment and these boxes could be omitted.

[0081] The openings 520 to 540 here have the shape of an irregular hexagon, but other shapes could be considered. Each shutter is in the form of a flat plate whose contour is adapted to that of the opening.

[0082] This fifth embodiment also includes variants. Thus, one or more of the walls 50 to 59 could be without shutters or solid.

[0083] In this embodiment, the wave energy device supports wind turbines on the upper part 67 of the structure 5. In practice, each wind turbine 600 to 660 is fixed on a float of the structure 5.

[0084] The wind turbines illustrated in Figures 6 and 7 are vertical axis wind turbines described in document EP3426917. Compared to horizontal axis wind turbines, they have the advantage of not having their performance degraded despite the movements of the floats, up to heel / pitch angles of up to 10°. The use of such wind turbines therefore makes it possible to reduce the dimensions and weight of the floats and therefore the anchoring efforts.

[0085] Illustrates a sixth embodiment in which the structure 7 of the wave energy device comprises twelve walls 700 to 711 connected together, two by two, by twelve floats 712 to 723 to form a polygonal outer belt. The structure 7 is again a closed structure. These twelve walls are non-coplanar and form a non-zero angle between them, two by two. In this example, the walls are substantially identical, and this angle is 150°.

[0086] This structure 7 has a bottom and an upper part (not referenced in the figure).

[0087] Each of the twelve walls 700 to 711 has an opening (not shown in the figure). In each opening, a flap 730 to 741 is mounted, movable in rotation around an axis (not referenced in the figure) which extends in the plane of the wall in which it is provided and which is substantially parallel to the bottom of the structure or else substantially horizontal when the structure 7 is placed on a flat support.

[0088] This sixth embodiment also includes variants. Thus, one or more of the walls 700 to 711 could be without shutters or solid.

[0089] The operation of the wave energy device according to the invention will now be described with reference to the. This description is focused on the device illustrated in the but it can be transposed to all the devices described.

[0090] It should first be noted that in operation, the structure floats on the sea, the floats being anchored to the seabed by anchors, dead weights or any other system connected by textile lines and / or chains, to stabilise the structure at a specific location.

[0091] In all the embodiments which have been described, the structure of the wave energy device is designed so that in operation, the horizontal axis of rotation of each flap is not submerged but on the contrary above the waterline of the structure.

[0092] Furthermore, each structure is sized so that in operation, each shutter is partially submerged and, preferably, approximately ¾ submerged.

[0093] For this purpose, a flap can be made of any material suitable for use at sea. The density of the flap is strictly greater than 1. The density is defined here as the ratio between the density of the flap and the density of the seawater. Preferably, the density of the flap is also less than 5. The flap is, unlike a float, a heavy structure which cannot float and which is returned to a vertical position under the effect of gravity.

[0094] The swell thus causes an alternating rotational movement of each flap 201, 211 of the structure around its axis. In fact, each flap behaves like a mobile barrier which creates a difference in water height between the upstream and downstream of the flap and therefore a differential pressure on the height of the flap. This pressure itself creates a force which generates a moment around the axis of rotation of the flap and generates an angular speed, therefore mechanical energy.

[0095] This structure allows the shutter's movements to be controlled, which systematically follow those of the swell. Furthermore, by forming a mobile barrier, the shutter draws energy from the swell, this energy being greater than that drawn by a float, at equivalent scales.

[0096] Illustrates an example of means 8 for converting the mechanical energy of the shutter 201. These means can be provided for each shutter, for example the shutter 201 of the structure 2, or partially shared.

[0097] These means 8 here comprise a piston 80 driven in translation by the rotation of the flap 201, for example by means of a connecting rod 81 which connects the piston to the flap. No other intermediate system, such as a crankshaft, is necessary.

[0098] As schematically illustrated, thanks to the structure of the wave energy device, during operation, the piston is not submerged but on the contrary positioned out of the water. This has the advantages of protecting the piston from corrosion due to sea water and making its maintenance easier.

[0099] The piston moves inside a cylinder 82 which extends vertically (or in the plane of the flap or wall) at rest). In this embodiment, the connecting rod 81 vertically connects the piston 80 to the flap 201 at rest, that is to say that, in this rest position where the flap 201 is vertical, the connecting rod 81 is aligned with the piston 80 and is in the plane of the flap 201.

[0100] Other embodiments will be described with reference to Figures 13 to 17.

[0101] The piston is associated with a control valve 83 which regulates the flow of hydraulic fluid displaced by the piston to low and high pressure reservoirs 84, 85 so as to generate a flow driving a hydroelectric generator 86 by pressure difference. The reservoirs and the generator are connected by a hydraulic circuit. The hydroelectric generator 86 comprises a hydraulic turbine 86a connected to an electric generator 86b which transforms the torque and rotation into electricity. The electric current produced by the generator is then transported to land to an electrical network 87 or storage means (not shown). It can also be consumed on site, in particular when the device is integrated into an offshore platform.

[0102] The conversion means also comprise regulation means 88 which are capable of regulating the electrical power or voltage generated by the generator 86 as a function of the energy of the swell and therefore the rotation of the flap. Thanks to this regulation, the energy extracted by the generator brakes the hydraulic turbine, which increases the pressure in the hydraulic circuit and slows down the pistons and therefore brakes the flap. This regulation makes it possible in particular to optimize the energy recovery as a function of the sea state.

[0103] Regulation can be performed “wave by wave” to optimize recovery.

[0104] Since structure 2 illustrated in

[0000] is a closed structure, a resonance phenomenon can occur inside the structure, producing an increase in the amplitudes of the free surface of the sea. This makes it possible to optimize energy recovery. The same applies to the devices illustrated in

[0000] 4 to

[0000] 8.

[0105] To obtain such resonance, it is preferable that the structure of the device has solid walls or walls provided with a flap on its outer belt, the walls having an opening without a flap being rather provided inside this belt (if such walls are present).

[0106] It is also noted that the wave energy devices according to the invention allow multidirectional wave recovery, while being in a fixed position, which also makes it possible to optimize energy recovery while avoiding the presence of complex connectors between the export cables and the device.

[0107] Generally, in all embodiments, the upper part of the structure of the wave energy device may be open or closed. Furthermore, the bottom is preferably partially closed, for example by plates (not shown in the figures) which have an anti-heave effect.

[0108] For illustration purposes, the length of a wall of the device is advantageously between 20 and 100 meters. This is why the structure and in particular its walls can be designed to integrate the energy conversion means, the energy storage means and also the various means associated with the wind turbines when these are planned.

[0109] The present invention should not be limited by the described embodiments, including those shown in the drawings or illustrated in the specifications, which are given by way of example or illustration and not by way of limitation.

[0110] Floats can be made of metal, composite fibers, concrete or any other material suited to their functions and constraints.

[0111] Other variants of the invention may still be envisaged.

[0112] Thus, a wall can have several openings and not just one opening, each of them being fitted with a shutter.

[0113] Furthermore, the axis of rotation of a shutter could have a different orientation than that previously described, for example perpendicular to the bottom.

[0114] The floats preferably have a battery shape, and in particular the shape of a cylinder with a round, polygonal or elliptical section. The invention is however not limited to this embodiment and other float shapes could be envisaged.

[0115] The floats may or may not be fitted with a box widening their base, as described with reference to point 7.

[0116] Furthermore, as illustrated in, any wall of the structure, for example the wall 10, may also comprise, on the bottom side of the structure, a box 103 whose section is wider than that of the wall and whose height is less than this section. Each box therefore widens the base of a wall and contributes to reducing the heave effect.

[0117] A flap of the wave energy device is not necessarily a flat plate. It may have a concave shape as illustrated in Figures 10 to 12. The flap 800 illustrated in the side view has the shape of a quarter of an ellipse. The flap 801 illustrated in the side view has the shape of a half-ellipse, while the flap 802 illustrated in the side view has the shape of a spoon. Other concave shapes could still be envisaged.

[0118] In all cases, the flap is mounted in the structure of the wave energy device in such a way that the concavity is facing towards the inside of the structure or towards the downstream side of the swell. These particular shapes make it possible to increase the amount of energy recovered from the swell.

[0119] The wave energy device can also be used to support other types of wind turbines, an offshore photovoltaic plant or any other offshore application requiring a large surface area and energy to operate.

[0120] It should be noted that the wave energy device according to the invention is designed in a modular manner, consisting of unitary elements built in series with a naval construction technique based on the use of thin sheets with stiffeners, this technique being able to be implemented anywhere in the world.

[0121] The piston of the wave energy conversion means can take different forms which are illustrated in figures 13 to 17.

[0122] Thus, still with reference to the flap 201 of the structure 2, it is shown that the flap 201 is connected to two pistons 90, 91 which each slide in a cylinder 90a, 91a extending vertically (or in a plane parallel to that of the flap), the connection between the flap and each piston being obtained by means of a connecting rod 90b, 91b. In this embodiment, each connecting rod 90b, 91b horizontally connects each piston 90, 91 to the flap 201 at rest, that is to say that, in this rest position where the flap 201 is vertical, each connecting rod 90b, 91b is perpendicular to a piston 90, 91 and to the plane of the flap 201.

[0123] The illustration shows a piston 92 sliding in a cylinder 92a extending horizontally (or else perpendicular to the flap 201), the connection between the flap and the piston being obtained by means of a connecting rod 92b. In this embodiment, the connecting rod 92b connects the piston 92 to the flap 201, such that, in the rest position where the flap 201 is vertical, the connecting rod 81 is perpendicular to the piston 92 and is in the plane of the flap 201.

[0124] Illustrates a piston 93 sliding in a vertically extending cylinder 93a, the connection between the flap and the piston being obtained by means of a connecting rod 93b. In this embodiment, the connecting rod 93b connects the piston 93 to the flap 201, such that, in the rest position where the flap 201 is vertical, the connecting rod 81 is perpendicular to the piston 93 and to the plane of the flap 201.

[0125] The embodiments illustrated in Figures 13 to 15 are more suitable for high powers but they require space to connect the piston(s) to the flap, while protecting the piston(s) from seawater.

[0126] Illustrates the flap 201 connected to two pistons 94 and 95 which each slide in a cylinder 94a, 95a extending in an inclined and symmetrical manner relative to the plane defined by the flap 201, the angle between each piston and this plane being an acute angle. The connection between the flap and each piston is obtained by means of a single connecting rod 98.

[0127] Illustrates the flap 201 connected to two pistons 96 and 97 which each slide in a cylinder 96a, 97a extending in an inclined and symmetrical manner relative to the plane defined by the flap 201, the angle between each piston and this plane being an obtuse angle. The connection between the flap and each piston is obtained by means of a single connecting rod 99.

[0128] The embodiments illustrated in figures 16 and 17 are more suitable for reduced powers and spaces because they allow the pistons to be connected directly to the axis of rotation of the shutter.

[0129] Thus, in all the embodiments illustrated in Figures 13 to 17, the pistons are not submerged but on the contrary positioned out of the water, as in the embodiment illustrated in.

Claims

Wave energy harvesting device comprising a structure (1, 2, 3, 4, 5, 7) intended to float and to be anchored on a seabed, in use, this structure comprising at least a first and a second wall (10, 11; 20, 21, 22; 30 to 38; 40 to 43; 50 to 59; 700 to 711), the first and second walls being non-coplanar, one of them (10; 20, 21; 30 to 35; 40, 42; 50 to 59; 700 to 711) comprising at least a first opening (100; 520, 530, 540) and a first flap (101; 201, 211; 301 to 351; 401, 421; 501 to 551; 730 to 741) mounted inside said at least one first opening while being movable in rotation about a first axis (102; 522,532,542) so as to be able to be moved in rotation about said first axis under the effect of the swell and generate, in operation, mechanical energy, two adjacent walls of the structure being connected together by means of a float (12; 23,24,25; 39a to 39f; 44 to 47; 60 to 66;712 to 723) to form a polygonal structure having a bottom (15; 60) and an upper part (16; 67) opposite each other, the first flap being vertical in the rest position, and behaving like a mobile barrier which creates a pressure difference over the height of the flap to generate mechanical energy, the device also comprising means for converting (8) the mechanical energy of the flaps into electrical energy.; Device according to claim 1 wherein said second wall (21) comprises at least one second opening and a second flap (201) mounted inside the second opening while being movable in rotation around a second axis. Device according to claim 1 or 2 in which the axis (102; 522,532,542) of a flap is substantially parallel to said bottom. Device according to one of claims 1 to 3 in which said conversion means (9) comprise, connected to each of the flaps of the structure, at least one piston (80) driven in translation by said flap (201). Device according to one of claims 1 to 4 in which said bottom is partially closed. Device according to one of claims 1 to 3 in which said structure (2, 3, 4, 5, 7) comprises at least three walls (20, 21, 22; 30 to 38; 40 to 43; 50 to 59; 700 to 711) connected together so as to form an outer belt, said structure being closed. Device according to one of claims 1 to 6 in which at least one of said walls is solid. Device according to any one of claims 1 to 7 wherein said structure (3, 4, 5, 7) comprises at least five walls connected to each other, at least four of them (30 to 35; 40 to 43; 50 to 55) forming an outer belt and at least one of them (36 to 37; 56 to 59) being placed inside said belt. Device according to any one of claims 1 to 8 wherein said structure supports at least one wind turbine and / or one photovoltaic power station. Device according to any one of claims 1 to 9 in which at least one float (12, 13; 62 to 65) of said structure and / or at least one wall (10) provided with a flap of said structure comprises(s) an enlarged box (17, 18; 62a to 65a; 103) on the side of the bottom of said structure. Device according to any one of claims 1 to 10 in which at least one of the flaps of said structure has a generally concave shape, the concavity being turned towards the interior of said structure. Device according to any one of claims 1 to 11 in which the flap has a density strictly greater than 1.

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