Apparatus For Converting Or Absorbing Energy From A Moving Body Of Water

Abstract

There is provided an apparatus for absorbing or converting energy from a moving body of water. The apparatus comprises an energy capture element (3) which, in use, moves in response to movement of the body of water in which the energy capture element (3) is placed, and an elongate guide element (1) defining a guide path along which the energy capture element (3) can move. The energy capture element (3) is a volume. In use, the energy capture element (3) and the guide element (1) are arranged so that the energy capture element (3) moves along the guide path in a substantially horizontal plane in response to differences in water pressure along a length of the energy capture element (3) parallel to the guide path and in response to movement of the body of water surrounding the energy capture element (3).

Claims

1. Apparatus for absorbing or converting energy from a moving body of water, the apparatus comprising an energy capture element which, in use, moves in response to movement of the body of water in which the energy capture element is placed, and an elongate guide element defining a guide path along which the energy capture element can move, wherein the energy capture element is a volume, and wherein, in use, the energy capture element and the guide element are arranged so that the energy capture element moves along the guide path in a substantially horizontal plane in response to differences in water pressure along a length of the energy capture element parallel to the guide path and in response to movement of the body of water surrounding the energy capture element.

2-29. (canceled)

Description

[0057] Embodiments of the invention will now be described by way of non-limiting example with reference to the attached figures in which:

[0058] FIG. 1 illustrates a first embodiment of the invention;

[0059] FIG. 2 illustrates a second embodiment of the invention;

[0060] FIG. 3 illustrates a third embodiment of the invention;

[0061] FIG. 4 illustrates a fourth embodiment of the invention;

[0062] FIG. 5 illustrates a fifth embodiment of the invention; and

[0063] FIG. 6 illustrates a sixth embodiment of the invention.

[0064] FIG. 1 shows a first embodiment of apparatus 100 according to the invention. The apparatus 100 has a guide element 1, a support structure 2 and an energy capture element 3. The energy capture element 3 is a moving member that is acted upon and responds to movement and/or pressure changes (surges) in the body of water in which it sits.

[0065] In a wave configuration, the moving member or energy capture element 3 moves back and forth along the guide element 1 in use, propelled by the water motion and/or pressure surges, and this motion is absorbed, to be either converted into energy or to be dissipated locally.

[0066] In a wave and tidal or in a purely current-tidal configuration, the cross section with respect to the flow of the moving member is reduced when it reaches the downstream side of the guide element 1 by opening vents (not shown) on the moving member 3 using a mechanism (not shown) housed inside it. At this point, the moving member 3 is brought back to the upstream end of the guide element 1 by an active system (not shown) at the upstream end of the guide element 1, where the reduction in frontal area is reversed and a new energy extraction (or dissipation) cycle begins. In an alternative implementation of this embodiment, the moving member 3 has a reduced cross section when rotated with respect to the flow. In this alternative implementation, a mechanism housed on the moving member 3 or on the guide element 1 rotates the moving member 3 when it reaches the downstream end of the guide element 1 in order to reduce its frontal area. The moving member 3 is then returned to the upstream end of the guide element 1, rotated to a position that returns the frontal area to its initial, greater extent, and then a new cycle begins.

[0067] The capacity to reduce the flow cross section can also be used to adapt the device to the wave regime or to the tidal/current regime, so that if the waves are too energetic or the current flow is too fast or too turbulent or both the moving member can be given a reduced frontal area to be less affected by waves or currents or both, and when the waves or currents become less energetic, the cross section can be increased back.

[0068] The guide element 1 is formed by two parallel and linear beams 4, 5 supported at each end on the support structure 2, which holds the beams 4, 5 in linear arrangement. In this embodiment of the invention, the support structure 2 is formed from two end sections 6. Each end section comprises two leg elements 7, two corner elements 8 and a cross bar 9. These sections are joined to form a roughly U-shaped frame. The support structure 2 lies directly on the sea floor, or riverbed, and is kept at its position via its weight (gravity based mooring), anchors or harpoons or similar devices, or both. The parallel beams 4, 5 of the guide element 1 define a guide path along which the moving member 3 can move. The support structure 2 is positioned so that the guide path described by the moving member is a generally horizontal line.

[0069] The moving member 3 is positioned on top of two parallel and linear beams 4, 5 that make up the guiding member 1. A system with just one beam or more than two could equally well be used, with no specific advantage related to the working principle of the device in one versus the other solution. These beams 4, 5 are variable in length, depending on the range of motion required for the location, and they can have a fixed length for a given location or they could be made to vary their length depending on the wave regime.

[0070] The moving member 3 moves along the guide element 1 by means of wheels working in a way similar to those of a roller-coaster, but it could also use coasters or magnetic levitation or other forms of guide. In a basic version of this embodiment, the guide element 1 and the associated wheels are taken from one of the designs used in roller-coasters. The beams 4, 5 can be made of any suitable material, such as steel, and the wheels can be made of any suitable material, such as a plastic material possibly reinforced with steel. The beams 4, 5 can have any suitable sectional shape depending on the geometry of the wheel system used to attach to them (for example the section can be circular, or hexagonal, or it can be a T-shaped or H-shaped section like that of commercial steel profiles), and will typically extend for all the length of the support structure 2.

[0071] The support structure in a basic version of the embodiment could be made of steel profiles of any suitable sectional shape, welded together. The support structure can be just laid on the sea floor, keeping its position due to its weight, of if appropriate it can be bolted to the ground with various standard devices used normally to this end in underwater engineering.

[0072] The moving member 3 of the described embodiment is made of fiberglass, and has the general shape of a parallelepiped (although other shapes, like cylindrical or spherical ones, or a hydrofoil profile are possible). The shape influences the efficiency of the extraction, but any shape will result in energy absorption so no particular shape is needed to make the device work. If the moving member needs to have different cross sections at different angles, the parallelepiped may have a rectangular shape with one side significantly longer than the other, as shown in FIG. 1. If the moving member is a hydrofoil, the guide element will generally be transverse to the tidal flow (not necessarily at 90 degrees, especially in case a combined wave and tidal function is expected). The moving member 3 can be rigid, in the sense that its shape does not substantially change under the action of the waves. It is possible to have variations of the general structure of the device in which the shape of the moving member can be actively changed, to adapt it to the sea state (for example by changing its displacement or its cross section, or its profile especially in case of a hydrofoil shape, or any combination of these).

[0073] The apparatus 100 also includes a power transfer system, or power converter (not shown) arranged to extract and convert energy from the movement of the energy capture element 3 along the guide path. In this example, the power converter is an electro-mechanical device housed on the guide element 1, which converts the relative motion between the moving member 3 and the support structure 2 into electricity. Alternatively, the power converter could be a friction system included in the guide element 1, which dissipates energy in the form of heat. The power or energy transfer mechanism is not described in detail. It can be one of the known methods of converting relative movement of two bodies into energy or power. In a wave and tidal implementation, a system must be in place to drive the moving member upstream during half of the cycle, or another system must be in place to bring it back, like a system to invert the general force direction (for example if the guiding member is transversal to the flow and the moving member has a hydrofoil profile, a system to change the hydrofoil shape in order to redirect the resulting force).

[0074] For example, the power converter could comprise a belt and pulley power take off system, in which a belt is put into motion by the moving member and drives an electrical generator.

[0075] Although the power converter may preferably be housed in the guide element 1, in some variations of this embodiment it can be also housed on the support structure 2 or in the moving member 3. In this last case the large volume of the moving member (typically in the order of one cubic meter for each kilowatt of power to be extracted) will provide ample room to house this equipment. Alternatively, the power transfer system could be formed by a rack and pinion system, where the rack is fixed on the support structure and the pinion is attached to an electrical generator housed in the moving member. In this case, either the energy is dissipated or accumulated locally inside the moving member (for example via resistance dissipating it as heat or with a fuel cell producing chemicals from it and from the surrounding sea water and/or from a chemical precursor like freshwater or ammonia housed in the device), or it will be moved away from it through a cable or similar energy transport device. The power converter could include a different power take off system, based on rack and pinion system, belt, maglev or other or a magnetic dissipation device (like the ones used to slow down some types of roller-coasters). In the case of maglev suspension, the maglev system can be used to extract the energy.

[0076] FIG. 2 shows a second embodiment of apparatus 200 according to the invention. This embodiment is the same as apparatus 100, described above with reference to FIG. 1, with the variation that the depth of the guide element 1, and thus the moving member 3, can be varied. The variation in depth can be used to protect the moving member and the structure from excessive energy in the sea state or excessive tidal or current speed, or to follow a change in the depth of the sea at the installation site due to tides, or both. It could also be used to avoid collision with surface boats, or to be able to perform maintenance without the intervention of divers.

[0077] In a basic version of the system illustrated in FIG. 2, the variation of depth is obtained by replacing the fixed legs of the support structure 2 with composite legs 10, which are made of two coaxial cylinders (11, 12). The external cylinder 11 is fixed on the sea floor, and contains a hydraulic piston (not shown) which can push the internal cylinder 12 to a pre-determined elongation. The upper part of the support structure can be made to be negatively buoyant, so that gravity will push it down to balance the push of the hydraulic pistons. The hydraulic pistons can be connected to a common hydraulic pressure circuit and their valves can be regulated by a programmable logic controller (PLC) housed on board the system. In a variation (not shown) of this embodiment, the up and down movement could be provided and controlled through a rack and pinion system housed in each of the legs, actuated by electrical motors controlled again by a central PLC controller. Apparatus 200 is otherwise the same as apparatus 100 described above with reference to FIG. 1.

[0078] FIG. 3 shows a third embodiment of apparatus 300 according to the invention, which is suspended below the surface of the body of water and is moored to the sea floor, or riverbed. In this arrangement the support structure 2 is positively buoyant, and kept at the operating depth by a mooring system 13, which can also possibly be regulated to change the operating depth in response to changes in the energy of the sea state or to changes in the depth of the water caused by tides or both. The guiding element could also have reduced section surface piercing components, used for example to stabilize its depth at a predetermined value. This version would be particularly indicated in rivers, or in areas at sea with very significant tidal ranges but reduced waves.

[0079] The positively buoyant support structure 2 can be composed by a welded watertight steel structure 14, to which are welded the legs 7 connected to the support structure of the guide element 1 (which is composed by two linear beams 4, 5 as in embodiment 1 or in embodiment 2). The rest of the structure can be exactly as in embodiment 1. The mooring on the sea floor is made of gravity bases connected to the floating structure through a standard tensioned mooring system. If the guide element is linked to the surface by surface piercing elements, the mooring lines can be slack and not taut. The length of the mooring lines connecting the structure 14 to the mooring weights (not shown) can be variable, so that the structure can be rotated or moved vertically or horizontally in the water column to adapt to the sea state (for example to take into account tides or to avoid excessive energy from storms) or to rotate the moving member and vary its cross section. Alternatively, the mooring system can be slack, so that in the case of waves the support structure reacts to the force received from the moving member (through the power interceptor components) via its displacement and inertia more than via its mooring lines. In this version of the present embodiment, the support structure will be long with respect to the wavelengths which are more interesting for energy transfer purposes, so that it will receive little overall resulting force from them (a length equal to half the wavelength would result in little or no total force). Also in this case by changing the length of the mooring lines the structure can be made to rotate or to change its average working depth. The rest of the arrangement is like the one represented in embodiment 1 and described above with reference to FIG. 1.

[0080] FIG. 4 shows a fourth embodiment of apparatus 400 according to the invention, which is suspended below and linked to the surface of a body of water. This version of the system is very similar to embodiment 3, but for the fact that in this arrangement the support (2, 14) of the guide element 1 is negatively buoyant, and kept at the operating depth through lines or cables connecting it to a system of surface piercing floaters or buoys 16. The operating depth can possibly be regulated by varying the length of the lines connecting the support structure 2, 14 to the floaters. There are also mooring lines (not shown in figure) connecting the structure to the sea floor, which in this case can be a slack mooring system. By acting on the mooring lines the whole structure can be made to rotate in the horizontal plane, to adapt to a changing direction of the waves. The rest of the arrangement is like the one represented in embodiment 1 and described above with reference to FIG. 1.

[0081] FIG. 5 shows a fifth embodiment of apparatus 500 according to the invention, which is suspended below the surface of the body of water and in which the moving member is underneath the support structure. In this arrangement the support structure 2 for the moving member 3 is positively buoyant so as to lie with its upper face 17 close to the surface (or slightly surface piercing) and the rest completely submerged. The moving member 3 is below the structure 2 and therefore always completely submerged. This embodiment can be obtained by taking embodiment 3, rotating it by 180 degrees along the main structure axis and including buoyancy elements in its platform 14 (see FIGS. 3 and 4). Alternatively (and as shown in FIG. 5), the support structure 2 comprises a latticed steel structure 18 provided with buoyancy elements (not shown) so as to be positively buoyant. Considerations on the mooring system are the same as for embodiment 3. The rest of the arrangement is like the one represented in embodiment 1 and described above with reference to FIG. 1.

[0082] FIG. 6 shows a sixth embodiment of apparatus 600 according to the invention, in which the guide path has a variable depth. In this arrangement, the beams 4, 5 of the guide element 1 are bent so that the guide path is divided along its length into two guide path sections 21, 22 that are collinear but vertically offset, so that they lie at different depths. A transition zone 20 connects the two sections 21, 22 at different depths. This arrangement allows the apparatus 600 to operate in two different regimes, where the moving member can be alternatively kept at a shallower depth (with less energetic sea states) or at a deeper one (with more energetic sea states). The remaining features of this embodiment can be exactly as those in embodiment 1. Variations of this embodiment can be made to resemble for the remaining features also embodiment 2, embodiment 3, embodiment 4 or embodiment 5 described above.

[0083] Some features of preferred embodiments of the invention are set out in the following numbered paragraphs:

[0084] 1. An apparatus for intercepting energy from waves and from currents, comprising a water impacting moving member mounted on a guiding member, the water impacting member being allowed to move in a generally horizontal reciprocating motion along the guiding member under the action of waves and currents save for possible transition zones, the system further being capable of absorbing at least in part the energy associated to the reciprocating motion of the moving member while going in a downstream direction with respect to the flow determined by a wave or by the current, and further being capable of reducing flow impact to adapt to the its intensity or during a generally upstream motion along the guiding member needed in a type of cycle used for extraction from currents, so as to attain a final overall positive energy balance also from extraction from currents.

[0085] 2. An apparatus as in paragraph 1, where the path determined by the guiding member is also slightly curved vertically or horizontally or both.

[0086] 3. An apparatus as in paragraph 1 or 2, where there are transition areas along the guiding member where the moving member path is made to move from one generally horizontal direction to another which can be at a different depth.

[0087] 4. An apparatus as in paragraph 1, 2 or 3, where a power transfer system housed on the apparatus uses electrical generators to absorb energy from the reciprocating motion of the moving member and convert it into electricity.

[0088] 5. An apparatus as in paragraph 1, 2 or 3, where a power transfer system housed on the apparatus uses a hydraulic pump to convert the reciprocating motion of the moving member into pressurization of water, which is then dispersed or used locally or at a different location

[0089] 6. An apparatus as in paragraph 1, 2 or 3, where a power transfer system housed on the device is a friction system converting the energy associated with the reciprocating motion of the moving member into heat.

[0090] 7. An apparatus as in any of the preceding paragraph, where the guiding member comprises one or more guiding beams and the moving member has corresponding rolling components guiding the moving member over them.

[0091] 8. An apparatus as in any of the preceding paragraphs, where the guiding member includes a magnetic levitation (maglev) device guiding the moving member over it.

[0092] 9. An apparatus as in paragraph 8 where the maglev device is acting also as a power transfer device converting the energy associated with the reciprocating motion of the moving member into electricity.

[0093] 10. An apparatus as in any of the preceding paragraphs, where the moving member remains rigid under the action of the waves.

[0094] 11. An apparatus as in any of paragraphs 1 to 10, where the guiding member is supported on a positively buoyant structure either reaching the water surface or suspended in the water column and kept in its position by a combination of any of the following: the inertia originating from its mass; its displacement; links to weights possibly laying on the sea floor.

[0095] 12. An apparatus as in any of paragraphs 1 to 10, where the guiding member is supported on a negatively buoyant structure either laid directly on the sea floor or suspended in the water column and kept in its position by a combination of any of the following: the inertia originating from its mass; its displacement; links to buoyant components possibly reaching the water surface.

[0096] 13. An apparatus as in any paragraph claim, where the position of the guiding member inside the water column can be modified to adapt to the sea state.

[0097] 14. An apparatus as in any preceding paragraph, where the orientation of the guiding member inside the water column can be modified to adapt to the sea state.