WO2013072274A1

WO2013072274A1 - Power station

Info

Publication number: WO2013072274A1
Application number: PCT/EP2012/072382
Authority: WO
Inventors: Jos Louis Marie SCHEPERS
Original assignee: Schepers Jos Louis Marie
Priority date: 2011-11-15
Filing date: 2012-11-12
Publication date: 2013-05-23
Also published as: GB201119639D0

Abstract

The invention relates generally to a floating power station having a barge consisting of two hulls and a water-wheel mounted thereon. The water is directed to flow in a concentrated state between the hulls, turning the wheel and generating electricity. The floating power station as described herein is anchored in the stream and comprises means to orient the water-wheel perpendicular to the flow of the stream. An improvement to existing and known floating water-wheels resides in the presence of further means to enhance the water current in between the hulls in a controllable manner.

Description

POWER STATION

The invention relates generally to a floating power station having a barge consisting of two hulls and a water-wheel mounted thereon. The water is directed to flow in a concentrated state between the hulls, turning the wheel and generating electricity. The floating power station as described herein is anchored in the stream and comprises means to orient the water-wheel perpendicular to the flow of the stream. An improvement to existing and known floating water-wheels resides in the presence of further means consisting of underwater wing shaped laths or wing shaped plates positioned in between the hulls, to enhance the water current in between the hulls and to control the orientation of the water-wheel to the stream surface .

BACKGROUND OF THE INVENTION

There are obvious reasons to try and convert the energy of flowing water in a current or tide into useful power and energy. Different from wind- or solar energy, the energy supply is continuous and remains available, allowing multiple power stations alongside the same river of coastline. As such, the availability of a device to convert the energy of flowing water in a current or tide into useful power and energy would provide the ability to exploit the enormous amounts of clean and sustainable energy of flowing water in a current or tide.

Tidal streams near lowlands and rivers crossing lowlands (in most parts of the world) rarely exceed the speed of 1,5 meters a second. The surface layer of these streams usually shows turbulence and sometimes multidirectional counter currents. Such velocities are typically insufficient to provide an opportunity for means to generate power, unless further infrastructure is utilized such as dams or weirs.

In order to address the foregoing problem, a number of attempts have previously been made for water-wheels that are suited to be position on a flowing stream and capable of producing power from the water flow.

PCT Publication WO 2011/031132 generally describes a floating power station with a submerged paddlewheel. In said instance the water is accelerated by means of a number of underwater slopes (I in figure 2 of WO 2011/031132) creating a narrowing duct for the water directed to the paddlewheel.

A similar approach can be seen in UK patent application GB 2 408 778. Also in this instance, a number of underwater slopes create a narrowing duct (See Figures 1, 14 of GB 2 408 778) for the water directed to the paddlewheel.

US publication US 2003/0014969 provides a floatable turbine apparatus for producing power from flowing water by means of a water-wheel suspended between two floatable bodies. In said instance the two floatable bodies have deflecting surfaces (14 in Figure 1 of US 2003/0014969) configured to direct the flowing water laterally into the flow channel and to enhance the energy of water flowing through the channel, towards the water-wheel. A similar approach to enhance the energy of the water flowing towards the water-wheel can also been found in US patent US 0, 525, 130. In said instance the front ends of the boats are provided with shoes having long bevelled or rounded inner sides, which converge toward their rear ends in order to concentrate the current between the boats.

In another UK Patent GB 701,716 describing a floating hydraulic power plant, the undershot wheel is mounted at the end of a convergent channel created using two convex floatable bodies, narrowing towards the wheel and having a guide plate pivoted about a horizontal traverse axis situated above the water level near the entry of the channel and extending close to the wheel. This guide plate can be partially submerged into the water to create a convergent nozzle just in front of the undershot wheel.

A further example of a floatable power plant is provided in UK patent GB 150,822 describing a rectangular shaped open ended trough or enclosure in which a water-wheel is adapted to rotate, and having a number of deflectors at its entrance to control the amount of water that can flow through the floating trough.

Where each of the foregoing proposals address some of the problems associated with a floating power station, further improvements are still required. Such as for example cased by the sway of the water, affecting the orientation and impact of the water-wheel vis-a-vis the water surface / flow.

It is accordingly an object of the present invention to provide further improvements to the existing and art known floating water-wheels by adding further means to enhance both the water current in between the hulls and to control the orientation of the water-wheel to the stream surface.

These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1. Top view of a schematic drawing of a water-wheel according to the present invention.

FIG. 2. Schematic drawing of a cross section of a water- wheel according to the present invention.

Fig. 3. Foto showing the dent like shaped blades as used in a particular embodiment of the present invention.

Fig. 4. Schematic side view of a water-wheel having dent like blades. Line B-A indicating the maximal submersion of the blade, and Line B-C indicating the thickness of the dent like blade. In this example the water wheel has an outer radius (Rl) of 1000 mm and a radius at the maximal submersion point (R2) of 700 mm.

Fig. 5. A Cross sectional view in the water channel to indicate the position of the upstream wings and how they create a wave towards the impact point with the water wheel. At the arrows marked (i) there is no change in velocity of the water in the channel. The suction face of the most upstream wing (3a) is facing the streambed and accelerates the water (arrows marked (s) ) up to the leading edge of the second wing (3b) . The suction face of this second wing is facing the water surface and pulls the accelerated water (arrows marked (s) ) over the wing up to the impact point with the water wheel. At the opposite end of this second wing, water velocity is significantly reduced (arrow marked (1) ) .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power station having a barge consisting of two hulls and a water-wheel mounted thereon, provided with means to concentrate the current between the hulls and characterized in that said means to concentrate the current between the hulls comprise one or more underwater wing shaped laths or wing shaped plates positioned in between the hulls.

In one embodiment the power station according to the present invention, comprises at least two wing shaped laths or wing shaped plates, positioned upstream of the water-wheel and eventually one positioned downstream of the water-wheel, and wherein said wing shaped laths or wing shaped plates taken together cooperate in generating a wave upstream of the water-wheel. In an even further embodiment the power station, has two wing shaped laths or plates upstream of the water-wheel. In particular further characterized in that the suction surface of the leading wing shaped lath or wing shaped plate is facing the streambed and the suction face of the second wing shaped lath or wing shaped plate is facing the stream surface.

In another embodiment the power station, has two wing shaped laths or plates upstream of the water-wheel, and one wing shaped lath or wing shaped plate downstream of the water-wheel. In particular further characterized in that the suction surface of the leading wing shaped lath or wing shaped plate is facing the streambed, the suction face of the second wing shaped lath or wing shaped plate is facing the stream surface, and in that the suction face of the wing shaped lath downstream of the water-wheel is facing the streambed.

A power station as described herein, and having a wing shaped lath or wing shaped plate downstream of the water- wheel, further characterized in that the suction face of the wing shaped lath downstream of the water-wheel is facing the streambed.

In a particular embodiment of the present invention, the underwater wings are characterized in that the length of the underwater wing shaped laths or wing shaped plates equals in width to the interval between the inner sides of the hulls.

In another embodiment, the power station is characterized in that the underwater wing shaped laths or wing shaped plates include one or more adjustable wing shaped laths or wing shaped plates.

In a preferred embodiment the floatable power station of the present invention will further comprise means whereby it may be anchored or otherwise fixed in a stream. In particular anchored. More in particular anchored using a triangle chain, downstream connected at the base (14) of the hulls making up the water channel, and at its upstream top (13) to an anchor rode. In one embodiment the floating power station of the present invention comprises means to orient the water- wheel perpendicular to the flow of the stream. In particular steering means, like a set of rudders, to manoeuvre the vessel in the stream. In one embodiment the power station further comprises means to prevent floating objects from entering the space between the hulls. In particular forwardly extending spars, which are connected at their front ends and hover over the surface of the water. In one object of the present invention the floating power station is used to drive a power generator, in particular an electrical power generator, wherein the kinetic power of the water-wheel is transferred to a power generator through a cog-wheel or set of gears, such as for example used by wind generators. In a particular embodiment the generator consists of a direct-drive generator. More in particular the power station according to the present invention has power generators at both sides of the water wheel . In one embodiment the water-wheel is a crossflow rotor, such as for example an Ossberger or Mitchell Banki Turbine. In a particular embodiment the water-wheel is a cross flow rotor characterized in that the vanes (or blades) are curved in the radial direction, being concave to the stream, their curvature increasing from the center (proximal to the horizontal shaft) to the tip (at the outer perimeter of the wheel) , such that the vane-tips are vertical when they leave the water. In another particular embodiment the water-wheel comprises dent like blades that are radially curved, both at the front and the back, such that the thickness increases from the tip towards a thickness at the maximal submersion point of the blades that compensates for the difference in diameter between the outer perimeter and the inner impact point at the maximal submersion point of the blades, and which are such that the vane-tips are vertical when they leave respectively enter the water.

It is also an object of the present invention to provide a water-wheel having dent like blades as defined herein.

The water-wheel in its different embodiments may have two or more compartments with different impact angles along the length of the water-wheel.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, a floating power station according to the invention will be further clarified. The intention of this description is only to further explain the general principles of the present invention, therefore nothing in this description may be interpreted as being a restriction of the field of application of the present invention or of the patent rights demanded for in the claims. In a first aspect, the present invention provides a power station having a barge consisting of two hulls (1) and a water-wheel (2) mounted thereon, provided with means to concentrate the current between the hulls and characterized in that said means to concentrate the current between the hulls comprise one or more underwater wing shaped laths (3) or underwater wing shaped plates (3 ) positioned in between the hulls.

In analogy with the floatable power stations described in US 2003/0014969, US 0,525,130, GB 150,822 and GB 701,716; the two hulls create a channel (4) for the water flowing towards the water-wheel and the basic elements found in the aforementioned power stations to enhance the energy of the water flowing between the hulls, such as deflecting surfaces at the upstream ends of the hulls (such as for example found in US 2003/0014969 and GB 150, 822) or the shoes at the upstream ends of the hulls (such as for example found in US 0,525,130); may be present as part of the means to concentrate the current between the hulls in the present invention.

Different from the art-known embodiments, in the present invention the means to concentrate the current between the hulls further comprise one or more underwater wing shaped laths or underwater wing shaped plates positioned in between the hulls. The presence of said wing shaped laths or wing shaped plates, not only further accelerates the water flowing through the channel, but also stabilizes the vessel on the stream. The presence of the wings will results in an improved flow profile as the water approaches and passes over the structure, reducing drag and turbulence of the water in the channel with eventual loss of current stream at the impact point with the water- wheel. The wings capture the current, guide it through the channel, and accelerate it towards the impact point with the water-wheel. As such lateral loss is minimized, and pitching of the vessel prevented. In capturing the current, no further closure at the base of the channel is required to confine the current to the channel, such as for example seen in the open ended trough of GB 150,822.

As used herein, and evident from the figures hereinafter, the wing shaped laths or plates, have an aerofoil form as seen in cross-section. Given their application in water as the working fluid, they are also referred to as hydrofoils. These foils are shaped to move smoothly through the water causing the fluid to be deflected, differently affecting the streamlines at either side of the foil and thus resulting in a pressure difference over the foil in accordance with Newton's Third Law of Motion. This pressure difference is accompanied by a velocity difference, which in accordance to Bernoulli's principle, correlates to the lift force generated by the foil. At one face of the foil the average velocity of the working fluid will be lower compared to the average velocity at the opposite side, resulting in an under-pressure at said side of the foil, hereinafter also referred to as the suction face of the foil (the suction surface of the wing shaped laths or wing shaped plates used in between the hulls of the floating power station according to the present invention) .

In principle there is no particular limitation as to the shape of the foil in cross-section, in as far said shape results in a deflection of the water, with the formation of a suction surface, it can be used within the object of the present invention. Typical aerofoil shapes include flat bottom aerofoil, semi-symmetrical aerofoil, asymmetrical aerofoil and symmetrical aerofoil. In a particular embodiment of the present invention, the wing shaped laths or wing shaped plates have either a flat bottom aerofoil shape or asymmetrical aerofoil shape in cross-section. In case more than one underwater wing shaped laths or wing shaped plate is used, either of them may independently have a cross sectional foil shape selected from a flat bottom aerofoil, semi-symmetrical aerofoil or asymmetrical aerofoil; in particular selected from a flat bottom aerofoil, or asymmetrical aerofoil. In an even further embodiment, and in case more than one underwater wing shaped laths or wing shaped plate is used each of them has the same cross-sectional foil shape, in particular selected from a flat bottom aerofoil, or asymmetrical aerofoil. In case the underwater wings have an asymmetrical cross-sectional foil shape, the upper and lower camber of each of said wings may be chosen independently of one another. In a particular embodiment the upper and lower camber of the wing shaped laths or plates upstream of the water-wheel are identical. In one embodiment, the wing shaped laths or wing shaped plates bridge the distance between the inner sides of the hulls, i.e. are connected at either end to the hulls, i.e. have a length that equals in width the interval between the inner sides of the hulls. In one embodiment the means to concentrate the current between the hulls can be manipulated to optimize the current at the impact point with the water-wheel. In a particular embodiment the underwater wing shaped laths or underwater wing shaped plates can be manipulated to optimize the current at the impact point with the water- wheel. In said latter instance, manipulation is meant to refer to the possibility of altering the angle of attack (10) of the wing shaped laths or wing shaped plates in the moving fluid. In an even further embodiment, the wing shaped laths or wing shaped plates are rotably mounted to the hulls of the floatable water-wheel, more in particular at the aerodynamic center of the wing shaped laths or wing shaped plates. When in use, the power station according to the present invention is prevented from floating with the river. It accordingly further comprises means whereby it may be anchored or otherwise fixed in a stream. This anchoring or otherwise fixing of the vessel in the stream, shouldn't prevent an eventual lateral movement of the vessel, since controlled skidding or surfing of the vessel over the river may further increase the energy of the water flowing through the channel, towards the water-wheel. Consequently, in a preferred embodiment the floating power station of the present invention is anchored (in particular at both hulls, using for example a triangle chain) to the riverbed, and further comprises steering means, like a set of rudders, to manoeuvre the vessel in the stream. The triangle chain, downstream connected at the base (14) of the hulls making up the water channel, and at its upstream top (13) to an anchor rode, allows the vessel to manoeuvre itself to the position with the maximal water current within the range of the anchoring means, whilst retaining a proper orientation (more or less perpendicular with respect to the water current) of the water wheel. In other words, the triangle chain as described herein, allows controlled skidding or surfing of the vessel over the river.

By controlling the tension on the anchoring means, one buffers eventual disturbances, such as for example vortexes or waves, in the water flowing through the channel. Such disturbances may for example result from the bow wave of a vessel passing at the river. The waves and eventual vortexes thus created will locally disturbed the water current (water velocity and direction of flow) of the water in the channel between the hulls. To prevent that these disturbances will affect the rotation of the water-wheel, the tension on the anchoring is preferably controlled. By controlling the tension on the rode, an eventual drop in water velocity will be counteracted by the tension on the rode pulling the power plant forward (upstream) . In its simplest form this may for example be achieved by adding one or more weights to the rode of the anchor. Accordingly in a further embodiment, the anchoring means are further characterized in comprising means to control the tension on the anchor, in particular consisting of one or more weights to the rode of the anchor .

The connection point (s) of the anchor to the floating power station should be such to prevent the formation of vortexes in the water flowing through the channel. To said extend the connection point (s) are preferably at the base of the hull (s) making up the water channel, in particular at or near the outer (distal from the water channel) perimeter of said hull (s) , more in particular at or near (just upstream) the horizontal line through the centre of buoyancy. In an even further embodiment the connection point (s) are at one or more of the aerodynamic center line(s) of the wing shaped laths or wing shaped plates positioned below the water level in between said hulls .

In said embodiment of the present invention wherein the floating power station comprises two underwater wing shaped (laths or plates) in front (upstream) of the water- wheel, the anchoring mean (in particular a triangular chain) is preferably attached to both hulls at about or in-between the aerodynamic center line of the second wing shaped (lath or plate) and the horizontal center line through the centre of buoyancy of the vessel; more in particular at the aerodynamic center line of the second wing shaped (lath or plate) . It has been found that this particular configuration damps pitching of the vessel and is beneficial to assure a proper orientation (water-wheel perpendicular to the current) of the vessel during skidding or surfing of the power station over the river. This particular configuration further assures that the downward pull of the anchor does not affect the angle of attack of the wings. It is accordingly a further objective to provide a power station according to the present invention, further characterized in that it comprises means to manoeuvre the vessel in the stream; in particular to orient the water- wheel perpendicular to the flow of the stream. In one embodiment, such means to fixate and orient the water- wheel perpendicular to the flow of the stream, include bow and stern lines or cables to connect the vessel to stationary objects in, or at the river banks. Alternatively, and as already mentioned above, said means to orient the water-wheel perpendicular to the flow of the stream may consist of steering means, like a set of rudders, optionally with an automated steering enabling remote control of the floating power station. In its general appearance, the power station according to present invention constitutes an open water channel guiding the water to the water-wheel bridging the two hulls. As such, any floating objects may enter the channel and may risk damaging or blocking the water-wheel from working. Consequently, in a further aspect, the floating power station according to the present invention may further comprise means to prevent floating objects from entering the space between the hulls. Any means suitable to prevent objects from entering the space between the hulls can be used, such as for example forwardly extending spars, screens, or grids fitted at the upstream edge between the hulls; or stationary objects, such as deflecting dams positioned upstream of the power station in the stream. In a particular embodiment the means to prevent floating objects from entering the space between the hulls, consist of forwardly extending spars, which are connected at their front ends and hover over - or rest upon (in particular hover over) , the surface of the water, thus forming a debris guard and preventing floating objects from entering the space between the hulls.

As is evident from the drawings, the water-wheel (2) in the power station according to present invention, is rotatable through a horizontal shaft (5) bridging the hulls (1) and mounted in bearings at each of said hulls, so that the shaft is above the water level and the blades of the water-wheel extend down into the water in the channel between the hulls. As such, the flow of the current is converted into a rotary motion that can be connected to any suitable machinery such as a water pump or power (electricity) generator (6) . In general, the wheel movement is relatively slow, and rotation speed is to be increased by a type of gearing to drive a power generator or pump, by direct or hydraulic transfer of rotational movement to the generator or pump. In a particular embodiment the kinetic power of the water-wheel is transferred to a power generator through a cog-wheel or set of gears, such as for example used by wind generators. In a particular embodiment transfer is realized using direct drive generators, more in particular at either side of the water-wheel. With such direct-drive generators, one eliminates the need for a gearbox, expected to result in substantial savings in maintance cost and in a reduction in weight. Furthermore, at low rotary speeds permanent magnet direct-drive generators are known to have the best load efficiency, and accordingly well suited in the power station of the present invention.

As the main energy transfer takes place at the initial impact point of the water flow with the blades of the water-wheel, the latter preferably consist of long horizontal blades (7) that are mounted on the periphery between two end flange supports (8) . In order to benefit from the additional energy that can be obtained as the water exists the rotor, the latter preferably consists of a crossflow rotor, such as for example an Ossberger or Mitchell Banki Turbine. In this type of rotor the water flow impacts on the rotor blade and then passes through into the rotor to exit at the other end. In a particular embodiment the water-wheel of the power station according to the present invention has two or more compartments (9) with different impact angles along the length of the water-wheel. Dividing the wheel in compartments with different impact angles results in a smoother rotational movement of the water-wheel. In a particular embodiment the wheel is divided in 1 to 12 compartments equally distributed over the length of the horizontal shaft (5) in-between the hulls.

The distribution of the impact angles (blades) across the wheel is such that the impact of the water is equally distributed over the horizontal shaft (5) . For example, when each compartment comprises 6 blades, the blades within one compartment are radially separated from one another by 60° and radially separated to the blades of the neighbouring compartment by 20°; when each compartment comprises 8 blades, the blades within one compartment are radially separated from one another by 45° and radially separated to the blades of the neighbouring compartment by 15°; when each compartment comprises 10 blades, the blades within one compartment are radially separated from one another by 36° and radially separated to the blades of the neighbouring compartment by 12°; when each compartment comprises 12 blades, the blades within one compartment are radially separated from one another by 30° and radially separated to the blades of the neighbouring compartment by 10°; etc ... .

Where a traditional cross flow rotor with multiple compartments is suitable within the context of the present invention, also the shape of the water-wheel blades (also referred to as vanes) influences the smoothness of operation. During the rotational movement of the water- wheel each blade has a face (hereinafter referred to as the front face (10) ) entering the water and a face (hereinafter referred to as the back face (11) ) leaving the water. In case the vanes simply consist of flat members, oriented in radial direction of the water-wheel, the force exerted by the water to the vanes at the waterline (closer to the horizontal shaft) , will be different to the force exerted by the water at the outer perimeter of the vanes of the water-wheel, due to the differences in diameter. This will inevitably lead to friction and irregular rotation of the wheel.

One way to compensate for this difference in force could be through the shape of the vanes (7) , such as for example shown in figure 2. Consequently, in one embodiment of the present invention the vanes are curved in the radial direction, being concave to the stream, their curvature increasing from the center (proximal to the horizontal shaft) to the tip (at the outer perimeter of the wheel) , such that the vane-tips are vertical when they leave the water. Through the curvature of the vanes the moment of force at the perimeter will be smaller compared to an inner section (closer to the horizontal shaft) , thus compensating for the difference in force by reducing the momentum at the outer perimeter. In as far this embodiment addresses the above-mentioned problem, the available energy is not fully exploited by this solution. It is accordingly desirable to have further optimizations on the energy transfer of the water current to the rotation of the wheel.

Instead of using flat, eventually curved, members for the water-wheel blades, better results are achieved using dent like blades instead (See for example Figures 3 and 4) . In said embodiment the blades are characterized in having a curved back face, closed to the center at the front. In a particular embodiment the dent like blades are such that the radial curvature of the back face (10) increases from the center to the tip; more in particular such that the vane-tips are vertical when they leave the water. In a further embodiment the closure at the front face of said dent like blades is flat, i.e. in line with the radial axis of the wheel. In a particular embodiment the front face of said dent like blades is also curved (11) ; in a more particular embodiment the front face of said dent like blades is concave, i.e. such that the radial curvature of the front face increases from the center to the tip; more in particular such that the vane-tips are vertical when they enter the water. Closure of the curved blades results in the displacement of a corresponding water volume and the generation of a corresponding hydrodynamic force adding to the energy transfer of the water current to the rotation of the wheel. With reference to Figure 4, in a particular embodiment of the present invention the radial curvature of the back face, eventually with a radial curvature of the front face, is such that the thickness of the dent like blades will increase from the tip towards a thickness at the maximal submersion point of the blades (point B in Figure 4) that compensates for the difference in diameter between the outer perimeter (Rl in Figure 4) and the inner impact point at the maximal submersion point of the blades (R2 in Figure 4) . For example, in case the water-wheel has an outer diameter of 2,00 meter, with a maximal submersion (line A-B in Figure 4) of 0,30 m. In said instance the outer periphery equals 2, 00 m x n = ± 6, 28 m; and the inner periphery at the maximal submersion point equals 1,40 x n = ± 4,40 m; or a difference of about 1,88 m to be distributed over the thickness of the dent like blades. Thus for example if to be distributed over 12 blades, the curvature of the dents should be such that at the maximal submersion point they have a thickness of about 1,88m : 12 = ± 0,157 m or 15,7 cm. With reference to Figure 4, for a water-wheel that has an outer diameter of 1,00 meter, with a maximal submersion of 0,30 m. In said instance the outer periphery equals 1,00 m x n = ± 3,14 m; and the inner periphery at the maximal submersion point equals 0,70 x n = ± 2,20 m; or a difference of about 0,94 m to be distributed over the thickness of the dent like blades. Thus for example if to be distributed over 12 blades, the curvature of the dents should be such that at the maximal submersion point they have a thickness of about 0,9 m : 12 = ± 0,0785 m or 7,85 cm (twice line B-C in Figure 4 ) . Again, in an even further embodiment the curvature at back face of the dents should be such that it will increase from the tip towards a thickness at the maximal submersion point of the blades that compensates for the difference in diameter between the outer perimeter and the inner impact point at the maximal submersion point of the blades, and which is such that the vane-tips are vertical when they leave the water. In a particular embodiment of the invention the dent like blades are radially curved, both at the front and the back, such that the thickness increases from the tip towards a thickness at the maximal submersion point of the blades that compensates for the difference in diameter between the outer perimeter and the inner impact point at the maximal submersion point of the blades, and which are such that the vane-tips are vertical when they leave respectively enter the water. It is accordingly a further object of the present invention to provide a water-wheel characterized in having blades as described hereinbefore. As already mentioned hereinbefore, a characterizing feature of the floatable power station of the present invention resides in the presence of one or more underwater wing shaped laths or plates positioned in between the hulls. In a particular embodiment the power station comprises at least two wing shaped shaped laths or plates, at least one positioned upstream of the water- wheel and one positioned downstream of the water-wheel, and wherein said upstream and downstream wing shaped shaped laths or plates taken together cooperate in generating a wave upstream of the water-wheel. This wave not only assist in accelerating the water flow through the channel, but also creates a fall between the front (upstream) and back (downstream) of the water-wheel, i.e. further enhancing the energy of the water flowing towards and through the water-wheel.

With reference to Figure 5, in another embodiment the power station according to the invention, comprises two wing shaped laths or wing shaped plates (3a, 3b) upstream of the water-wheel, characterized in that the suction surface of the leading wing shaped lath or wing shaped plate (3a) is facing the streambed and the suction face of the second wing shaped lath or wing shaped plate (3b) is facing the stream surface. To further reduce eventual lateral or downward loss of the kinetic energy of the wave thus created, the second wing shaped lath, proximal to the water-wheel may eventually extend or pass into a plate over the full width of the space between the hulls, guiding the water to the impact point at the front of the water-wheel .

It has been found that this configuration accelerates the water up to the impact point with the water-wheel. Testing in a river with a water current of about 1 m/s (water velocity at the arrows marked (i) in Figure 5) , this configuration accelerated the water over the suction faces of the wings to a velocity of about 1,4 m/s (water velocity at the arrows marked (s) in Figure 5) . Just under the second wing, water velocity was significantly reduced with currents of about 0,5 m/s. More downstream and where the currents re-join, water velocity in the channel normalizes to the water velocity of the river. In a particular embodiment the configuration shown in Figure 5, is complemented with a wing shaped lath of wing shaped plate downstream of the water-wheel. This downstream wing creates a further pressure difference between the front (upstream) and back (downstream) of the water-wheel resulting in a faster removal of the water entering the wheel. Optimal results are achieved when the suction face of the wing shaped lath or wing shaped plate downstream of the water-wheel is facing the streambed.

As evident from Figure 5, the wings are preferably positioned below the maximal submersion line of the water- wheel. Thus in an embodiment the power station (s) as described herein are further characterized in that the one or two wings upstream of the water-wheel are positioned below the maximal submersion line of the water-wheel. In an even further embodiment also the wing downstream of the water wheel is positioned below the maximal submersion line of the water-wheel.

In a particular embodiment and as already mentioned hereinbefore, to prevent lateral loss of the kinetic energy of the wave, the two wing shaped laths or wing shaped plates upstream of the water-wheel as described herein, bridge the distance between the inner sides of the hulls, i.e. have a length that equals in width the interval between the inner sides of the hulls.

In bridging the distance between the hulls, the hulls will act as wingtips and confine the wave into the channel. Consequently, the height of hulls should at least be such to confine the wave, both at the surface and below the water level, into the channel. Thus in one embodiment the height of hulls will be such that with reference to the deepest wing, the hulls extend at least one wave amplitude below said wing, and with reference to the wing closest to the surface, the hulls extend at least one wave amplitude above said wing. Due to the incompressibility of water, the wave generated through the underwater wings, gets shaped upstream of the most upstream underwater wing present in between the hulls. Again, and similar to the lateral confinement of the wave into the channel, the hulls should longitudinally extend sufficiently far upstream to confine the wave into the channel. In a particular embodiment the length of the hulls upstream of the aerodynamic center line of the most upstream underwater wing, equals at least half of the wavelength.

In an even further embodiment of the present invention, the power station is being characterized in that leading wing is a wing shaped lath and the second wing consists of a wing shaped plate, guiding the water in front of the water-wheel .

In each of the aforementioned embodiments, the wing shaped lath(s) or plate (s) upstream of the water-wheel may cooperate with a wing shaped lath or plate downstream of the water-wheel to create a water wave upstream of the water-wheel. The downstream wing will further accelerate the water-wheel by a rapid removal of the water entering the rotor. One way of optimizing the flow through the rotor wheel, i.e. assisting in the rapid removal of the water from the water-wheel, is by facing the suction face of the wing shaped lath downstream of the water-wheel towards the streambed. Thus in an embodiment of the present invention, the floating power station is further characterized in that is comprises a wing shaped lath or wing shaped plate downstream of the water-wheel. In a particular embodiment the suction face of the wing shaped lath or wing shaped plate downstream of the water-wheel is facing the streambed. In another embodiment, and as already mentioned hereinbefore in relation to Figure 5, the downstream wing is positioned below the maximal submersion line of the water-wheel. In addition to the foregoing effect on the water current, this downstream wing was shown to further stabilize the vessel in the current .

Claims

1. A power station having a barge consisting of two hulls and a water-wheel mounted thereon, provided with means to concentrate the current between the hulls and characterized in that said means to concentrate the current between the hulls comprise one or more underwater wing shaped laths or wing shaped plates positioned in between the hulls.

2. The power station according to claim 1, comprising at least two wing shaped laths or wing shaped plates, positioned upstream of the water-wheel and eventually one positioned downstream of the water-wheel, and wherein said wing shaped laths or wing shaped plates taken together cooperate in generating a wave upstream of the water-wheel.

3. The power station according to claim 2, comprising two wing shaped laths or plates upstream of the water-wheel

4. The power station according to claim 3, characterized in that the suction surface of the leading wing shaped lath or wing shaped plate is facing the streambed and the suction face of the second wing shaped lath or wing shaped plate is facing the stream surface .

5. The power station according to any one of claims 2 to 4, further characterized in that the suction face of the wing shaped lath downstream of the water-wheel is facing the streambed.

The power station according to any one of claims 1 to 6, wherein the length of the underwater wing shaped laths or wing shaped plates equals in width to the interval between the inner sides of the hulls.

The power station according to any one of claims 1 to 6, wherein the underwater wing shaped laths or wing shaped plates include one or more adjustable wing shaped laths or wing shaped plates.

The power station according to claim 1, further comprising means whereby it may be anchored or otherwise fixed in a stream.

The power station according to claim 1, further characterized in that it comprises means to orient the water-wheel perpendicular to the flow of the stream.

The power station according to claim 1, further comprising means to prevent floating objects from entering the space between the hulls.

The power station according to claim 1, wherein the kinetic power of the water-wheel is transferred to a power generator through a cog-wheel or set of gears, such as for example used by wind generators . (plus embodiment naar generator at both sides of the wheel)

The power station according to claim 1, wherein the water-wheel is a crossflow rotor, such as for example an Ossberger or Mitchell Banki Turbine.

13. The power station according to claim 12, wherein the water-wheel has two or more compartments with different impact angles along the length of the water-wheel .

The power station according to claim 13, wherein the water-wheel comprises dent like blades that are radially curved, both at the front and the back, such that the thickness increases from the tip towards a thickness at the maximal submersion point of the blades that compensates for the difference in diameter between the outer perimeter and the inner impact point at the maximal submersion point of the blades, and which are such that the vane-tips are vertical when they leave respectively enter the water .

A water-wheel comprising dent like blades that are radially curved, both at the front and the back, such that the thickness increases from the tip towards a thickness at the maximal submersion point of the blades that compensates for the difference in diameter between the outer perimeter and the inner impact point at the maximal submersion point of the blades, and which are such that the vane-tips are vertical when they leave respectively enter the water .