The present invention relates to a mooring system for a hydropower generator. More particularly, but not exclusively, the present invention relates to a mooring system comprising a floating platform having first and second fins extending from the underside of the platform, the spacing between the fins decreasing towards the rear of the platform. In a further aspect of the invention there is provided a hydropower system. More particularly, but not exclusively, the present invention relates to a hydropower system comprising a mooring system having a platform having at least one fin and a hydropower generator arranged on the platform, a portion of the hydropower generator being arranged so as to be submerged when the platform is floating in a stream.

Fouling from floating debris is a major problem for kinetic hydropower apparatus. Typically the hydropower apparatus is moored in a fixed position in a stream by two anchor chains with the apparatus arranged at the apex of the two chains. These chains tend to direct debris towards the apparatus.

This debris can have a number of adverse effects. The debris can damage the hydropower apparatus. It can also reduce the fluid flow into the hydropower apparatus. In addition, many hydropower apparatus operate at maximum efficiency when the fluid flow into them is laminar flow. Debris caught in the mouth of the hydropower apparatus can cause turbulence reducing the efficiency of the apparatus..

The fixed nature of the mooring can also be a drawback. The flow pattern of the stream can vary over time. For example the region of maximum fluid flow may be different in times of high fluid flow compared to low fluid flow. Because the mooring and hence the hydropower apparatus is fixed in position the apparatus will only be optimally positioned for a portion of the time. A further drawback is that the fixed mooring can tend to act as an island in the stream around which debris can nucleate. This debris can again alter the flow of the stream into the apparatus so reducing efficiency. The present invention seeks to overcome the problems of the prior art.

Accordingly, the present invention provides a mooring system for a hydropower generator comprising a platform having a deck and an underside and being adapted to float in a fluid stream, the platform comprising a prow portion; a body portion extending from the prow portion to a rear edge; the mooring system further comprising first and second fins extending from the underside of the platform, each fin having a lead edge and a rear edge, the fins being arranged on opposite sides of a centra! line extending from the tip of the prow to the mid point of the rear edge, each fin being inclined to the central line with the lead edge of the fin being a larger normal distance from the central line than the rear edge of the fin.

The mooring system according to the invention tends to sweep debris in the fluid stream to one side or alternatively rides over the debris if it is too large, so reducing the risk of damage to the hydropower apparatus, in addition, the mooring system moves itself in the stream so that it is always arranged in the region of maximum fluid flow.

Preferably, each of the fins extends to the rear edge.

Alternatively each of the fins extends beyond the rear edge to trail behind the platform.

The fins can be arranged symmetrically about the central line Both fins can pianar.

Alternatively both fins can be curved.

Alternatively the fins are not arranged symmetrically about the central line.

Both fins can be planar, one being inclined at a different angle to the central line to the other.

Alternatively one fin can be planar and the other can be curved.

Alternatively both fins can be curved.

Preferably the mooring system further comprises a central fin extending from the underside of the platform along at least a portion of the centra! line.

Preferably the lead edges are swept back.

In a further aspect of the invention there is provided a hydropower system comprising a mooring system as claimed in any one of claims 1 to 12; and, a hydropower generator arranged on the deck of the platform, a portion of the generator being arranged such that it is submerged when the platform is floating in the stream.

In a further aspect of the invention there is provided a hydropower system comprising (i) a mooring system comprising a piatform having a deck and an underside and being adapted to float in a fluid stream, the platform comprising a prow portion; and, a body portion extending from the prow portion to a rear edge; the mooring system further comprising at least one fin extending from the underside of the platform; and,

(ii) a hydropower generator arranged on the deck of the platform, a portion of the generator being arranged such that it is submerged when the platform is floating in a stream.

The hydropower system according to the invention tends to sweep floating debris to one side or in the case of large debris tends to ride over it.

Preferably the hydropower system comprises first and second fins extending from the underside of the platform, the first and second fins being arranged on opposite sides of a central line extending from the tip of the prow to a mid point of the rear edge.

The first and second fins can be parallel to the central line.

Alternatively each fin has a lead edge and a rear edge, each fin being inclined to the central axis with the lead edge of each fin being a larger normal distance from the central line than the rear edge of the fine.

The hydropower system can further comprise a central fin extending along at least a portion of the central line.

Preferably the lead edge of each fin is swept back. The present invention will now be described by way of example only and not in any (imitative sense with reference to the accompanying drawings in which

Figure 1 shows a mooring system according to the invention in perspective view;

Figure 2 shows the mooring system of figure 1 in side view;

Figure 3 shows an embodiment of a hydropower system according to the invention in side view;

Figure 4 shows an additional embodiment of a hydropower system according to the invention from below;

Figures 5(a) to 5(c) shown further embodiments of the mooring system according to the invention from below;

Figure 6 shows a further embodiment of the mooring system according to the invention from below;

Figure 7 shows a further embodiment of a hydropower system according to the invention from below; and,

Figure 8 shows a further embodiment of a hydropower system according to the invention from below. Shown in figure 1 is mooring system 1 according to the invention in perspective view. The mooring system 1 comprises a platform 2 having a deck 3 and an underside 4 and being adapted to float in a fluid stream. The platform 2 comprises a prow portion 5 and a body portion 6 extending from the prow portion 5 to a rear edge 7. The prow portion 5 comprises first and second side walls 8,9 which meet at a tip 10 at the front of the platform 2. In this embodiment the side walls 8,9 are slightly curved as shown. Other shapes of side walls 8,9, for example straight side walls 8,9 are possible. Extending from the deck 3 of the platform 2 at the tip 10 is a guard wall 11, the function of which is described below. Extending from the tip 10 is a mooring point 12, which is typically a loop or the like.

Extending integrally from the prow portion 5 to the rear edge 7 is the body portion 6. The side walls 13,14 of the body portion 6 are substantially straight with the separation between the side walls 13,14 decreasing in a direction away from the prow portion 5 as shown. At the rear of the platform 2 the rear edge 7 extends between the body portion side walls 13,14.

Extending from the underside 4 of the platform are first and second planar fins 15,16. The fins 15,16 extend generally in a direction from the prow portion 5 towards the rear edge 7. The separation between the fins 15,16 decreases in a direction towards the rear edge 7 as shown. In this embodiment the fins 15,16 extend as far as the rear edge 7 although in other embodiments they may not extend this far. In an alternative embodiment of the invention the fins 15,16 may extend beyond the rear edge to trail behind the platform when it is in use. Similarly, in this embodiment the fins 15,16 are shown as being arranged at the edges of the platform 2. In alternative embodiments they may be slightly inset.

One can imagine a central line 17 running from the tip 10 of the prow 5 to the rear edge 7. The fins 15,16 are arranged symmetrically about this length line 17 with each of the fins 15,16 being inclined at an equal angle to the length line 17. Each fin 15,16 has a lead edge (the edge proximate to the prow) and a rear edge. Each fin is inclined to the central line 17 with the lead edge 19 being a larger normal distance from the central line 17 than the rear edge. Also extending from the underside 4 of the platform 2 and partially along the central line 17 is a central fin 18. In this embodiment the central fin 18 extends to the rear edge 7. The lead edge 19 of each of the fins 15,16 is swept backwards as shown.

Typically a hydropower generator (shown in figure 3) is arranged on the top side of the platform 2. The generator has blades which overhang the rear edge but which do not hang further down than the bottom edges of the fins 15,16,18. A portion of the hydropower apparatus is arranged to be submerged when the mooring system is floating in the stream. This is described in further detail with reference to figure 3.

In use the platform 2 is arranged in a fluid stream with the blades in the water. The mooring point 12 is connected to an anchor chain. The anchor is arranged in the stream. As the stream flows past the platform 2 it rotates the platform 2 until the prow 5 faces directly into the stream. It is likely that the platform 2 will initially be slightly displaced from the region of fastest flow. Accordingly, one of the first and second fins 15,16 will be in a region of faster flow than the other. These fins 15,16 are shaped so that they generate a force which is angled away from the central length line 17 of the system. The fin 15,16 which is in the faster flow will generate a larger force than the fin 15,16 which is in the slower flow. This results in the central axis of the platform 2 being pulled towards the faster flow until the platform 2 is symmetrically arranged in the region of fastest flow.

If the flow of the stream changes then the platform 2 will move to new the region of fastest flow so ensuring the hydropower generator is operating at maximum possible output.

Any floating debris in the stream tends to float at or near to the surface of the stream. This debris is pushed to one side by the prow portion 5 of the floating platform 2, diverting it from the area directly behind the rear edge 7 in which the blades of the hydropower generator are arranged. This reduces the likelihood of the blades of the hydropower generator becoming damaged. The guard wall 11 prevents any debris from being urged onto the deck 3 of the platform 2.

In addition, the pointed prow portion 5 of the platform 2 and smooth sides 8,9,13,14 offer little opportunity for floating debris to attach itself to the platform 2. Floating debris therefore tends to get swept past the platform 2 downstream and will have little effect on the flow of fluid between the first and second fins 15,16.

The platform 2 may not be able to urge large pieces of debris to one side. Figure 2 shows the mooring system 1 of figure 1 from the side. As can be seen each of the first second and central fins 15,16,18 has a lead edge 19 which is swept backwards. The lead edge 19 of each of the fins 15,16,18 is inclined such that the top edge of the fin 15,16,18 (proximate to the underside of the platform) is longer than the bottom edge of the fin 15,16,18. The lead edge 19 of the central fin 18 is inclined at a shallower angle to the underside 4 of the platform 2 than the lead edges 19 of the first and second fins 15,16.

When a large piece of debris is swept downstream to the platform 2 it is swept under the platform 2 until it reaches the lead edge 19 of the central fin 18. The debris is then urged under the central fin 18 which in turn rises out of the water lifting the platform 2 out of the water and over the debris.

The fins 15,16,18 have a number of other advantages. They ensure that when water levels fall low the blades of the hydropower generator do not hit the stream bed.

The fins 15,16,18 also channel, smooth and accelerate the flow of fluid under the platform 2 and onto the blades of the hydropower generator, so increasing the output of the hydropower generator.

Shown in figure 3 is an embodiment of a hydropower system according to the invention shown from the side. This comprises a mooring system similar to that of figures 1 and 2 but includes a hydropower generator 20 arranged on the platform 2. The hydropower generator 20 comprises blades 21 which in use are arranged in the stream behind the rear edge 7 of the platform 2. As fluid flows past the blades 21 the blades 21 oscillate from side to side. The blades 21 are connected by lever arms 22 to a generator 23 on the platform 21 which converts the motion of the blades 21 into electricity. This is then transferred to shore by a power cable. Other forms of hydropower generator 20 are possible. The hydropower generator 20 could comprise turbines arranged in the stream behind the rear edge 7.

The portion of the hydropower generator 20 which is submerged in the water need not be behind the rear edge. It could be in front of the rear edge as described in further detail below.

In the above embodiments the prow portion 5 comes to a sharp tip. This shape is preferred in fast flowing streams. In an alternative embodiment the tip of the prow 5 is curved. Such tips tend to have greater structural strength.

Shown in figure 4 is an alternative embodiment of a hydropower system according to the invention. In this embodiment the first and second fins 15,16 are again arranged symmetrically about the central line 17. The fins 15,16 are slightly curved as shown. Such curvature increases the drag on the platform 2 but has the advantage of increasing the force exerted by the fins 15,16 on the platform 2 so urging it into the region of fastest flowing water.

This embodiment lacks the central fin 18. The first and second fins 15,16 are used to ride over large pieces of debris. The lead edges 19 of the fins 15,16 are swept backwards to facilitate this.

In this embodiment a slot extends through the body portion 6. A hydropower generator 20 is arranged on the deck 3 and a portion extends through the slot and into the fluid stream. In this embodiment this portion is shown ahead of the fins 15,16. In alternative embodiments the portion is set further back between the fins 15, 16 to provide protection from floating debris.

In further embodiments of the invention the fins 15,16 are not arranged symmetrically about the central line 17. Such an arrangement could be employed if for some reason it is desired that the platform 2 arrange itself slightly offset from the region of fastest flow. For example in a very wide stream the region of fastest flow may be very far from the river bank but it may be required that the platform 2 arrange itself close to the bank, either for maintenance reasons or to avoid shipping. The side of the platform 2 furthest from the bank with be in a faster flowing fluid than the side closer to the bank. In this case the fins 15,16 may be arranged asymmetrically so that the lateral forces generated by the fins 15,16 balance when the platform 2 is the correct distance from the bank. Figures 5(a) to 5(c) show further embodiments of a mooring system according to the invention from below. In figure 5(a) both the first and second fins 15,16 are planar but are inclined at different angles to the platform 2. In figure 5(b) one of the fins 15,16 is pianar and the other is curved, in figure 5(c) both fins are curved.

Shown in figure 6 is a further embodiment of a mooring system 1 according to the invention from below, in this embodiment the body portion 6 of the platform comprises two detachable sub portions 6a,6b. The first and second fins 15,16 extend from these two sub portions 6a, 6b. if it is required to change the configuration of the fins 15,16 then the sub portions 6a,6b are detached and replaced with other sub portions 6a,6b having different orientations of fins 15,16.

Shown in figure 7 is a further embodiment of a hydropower system according to the invention from below. The hydropower system comprises a mooring system 1, The mooring system 1 comprises a platform 2 having a deck 3 and an underside 4 and is adapted to float in a fluid stream. The platform 2 comprises a prow portion 5 and a body portion 6 which extends from the prow portion 5 to a rear edge 7. Extending from the underside of the platform 2 is a fin 18 which extends along a portion of the central line 17. The lead edge 19 of the fin 18 is swept back. Arranged on the platform 2 is the hydropower generator 20 having a portion which extends beyond the rear edge 7 of the body portion 6 and is submerged when the platform 2 floats in the stream.

As this embodiment of the hydropower system only has one fin 18 there is less drag on the platform 2 in use.

Shown in figure 8 is a further embodiment of a hydropower system according to the invention. This embodiment is similar to that of figure 7 except is comprises two parallel fins 15,16. This embodiment lacks the steering ability of the embodiments of figures 1 to 6 but will stiil either divert or ride over debris.