HK1141318A - Floating device for production of energy from water currents - Google Patents

Description

Floating device for generating energy from a water flow

Technical Field

The present invention relates to a device for generating energy from a water flow, as set forth in the introduction to the appended claims 1 and 6. The apparatus utilizes water currents below the surface of the ocean, lake, river or other body of water. Such currents may be formed, for example, by ocean currents, tidal changes (tidarvillation), and/or underwater terrain (e.g., straits, riverbeds, or other underwater narrow channels).

Background

There are a variety of known devices and methods for generating energy from ocean currents.

Norwegian patent application No. 19991984 describes a plant for the production of electrical energy from ocean and river currents. The apparatus is located entirely below the water surface and comprises several bladed turbines, a support system, a guy system and a generator. The turbine shaft is oriented perpendicular to the direction of water movement and the blades are airfoil shaped so that the turbine rotates in the same direction regardless of the direction of water movement. The turbine shaft is supported in a frame by means of a buoyancy tank, mounted on a support and bearing system, and the apparatus is made up of modules. The device has positive buoyancy regulated by a buoyancy tank and a guy cable system secured below the water surface, resulting in the device being held below the surface by the guy cable system. The apparatus employs conventional blades.

US 4864152 describes a floating water current power plant comprising a ring buoy which is moored at the bottom to an anchor by means of a bollard. All turbines can be replaced and mounted on a common beam and can be pivoted as a unit up to the surface within the area defined by the ring pontoon. The power plant is movable around the bollard with its top end connected to the front buoy and its bottom end fixed to the anchor.

Us patent No. 5,440,176 describes a submersible hydro turbine plant comprising turbine/generators suspended in various combinations below a tension leg type submerged platform.

Another example of a floating tidal power plant is mentioned in International patent application PCT/NO02/00249 (International publication No. WO03/006825A 1) owned by the applicant. This apparatus comprises a platform with a number of buoyancy elements, preferably one in each corner of the platform, so that the requirements for lateral and longitudinal stability are met also with minimal displacement. A number of support arms extend from the platform to each side, each holding a generator housing. The support arms are hinged at attachment points in the platform.

The known apparatus is basically designed with the aim of being placed in coastal waters where wind and wave forces are more moderate than they might be on open sea. There is a greater potential for energy recovery by placing the power plant in the sea or other harsh environment. There is therefore a need for a device for generating energy from a water flow, which can withstand greater environmental forces than hitherto known devices. Norwegian patent application No. 20070228 describes an apparatus for generating energy from a water flow, comprising a structure for submersion in water, and a plurality of turbine modules connected to the structure. The apparatus comprises a plurality of columns connected at one of their respective ends to the structure and also slidably connected to the buoyancy element, and each column is selectively and releasably attachable to the buoyancy element.

But the equipment located in the sea is subjected to large dynamic loads caused by waves and wind. In the above-described apparatus for positioning in the sea, the part of the buoyancy element located above the water surface may be subjected to waves and wind loads, which may place the entire apparatus in relatively large movements, in particular movements about the transverse axis of the apparatus. This presents structural challenges and has an adverse effect on turbine efficiency. There is therefore a need for a device which is less sensitive to large environmental forces.

Disclosure of Invention

Thus, according to the present invention, there is provided a device for generating energy from a water flow, comprising a first element, a second element and a plurality of turbine modules connected to the first element, characterised in that the second element is mounted to the first element in an approximately perpendicular relationship, the first element is adapted to be submerged below the water surface and the upper part of the second element protrudes above the water surface when the apparatus is in production.

The first element is preferably equipped with ballast tanks and a keel. Stabilizers may also advantageously be provided, preferably at both ends of the first element.

According to the invention there is also provided mooring arrangement for a floating plant, comprising mooring lines connected at one of their respective ends to the plant, characterized in that the mooring lines are connected at their respective second ends to buoys via attachment points and lines below the water surface, wherein the mooring lines extend substantially horizontally between the plant and the respective buoys.

The buoy is advantageously connected below the water surface via mooring lines (26a, 26b, 26c) to corresponding anchors on the bottom.

Drawings

Embodiments of the invention will become apparent from the appended patent claims, and from the following description with reference to the accompanying drawings. It is appreciated that the drawings depict only typical embodiments and are not to be considered limiting of the invention. In the drawings, like parts are denoted by like reference numerals, which will also be employed hereinafter.

Fig. 1 is a perspective view of an embodiment of the apparatus according to the invention.

Figure 2 is an end view of an embodiment of the apparatus according to the invention.

Fig. 3 is a side view of the apparatus shown in fig. 2.

Fig. 4 is a schematic view of an embodiment of the apparatus according to the invention, seen from above.

Fig. 5 is a schematic diagram of a mooring system according to the present invention.

Fig. 6 is a schematic diagram of a mooring system corresponding to that shown in fig. 5, in which several devices are connected in series.

Detailed Description

The device according to the invention is suitable for being partially submerged in water below the surface S. The device comprises a first body 10 and a second body 20, the first body 10 preferably being an underwater structure and the second body 20 preferably being an upwardly projecting structure as shown in fig. 1, wherein it can be seen that a portion of the second body 20 projects above the water surface S when the device is in an operative position in the water. Fig. 1 shows an embodiment in which the structures 10, 12 are shell-shaped bodies.

The second body 20 is hereinafter referred to as a tower 20, the tower 20 may also include a control room 31 and other equipment and facilities for operating the equipment, including ballast tanks (not shown) and access channels (not shown) to the underwater structure 10.

The projecting support arm 40 is mounted to the structure 10. As shown, the support arms are preferably mounted to respective opposite sides of the structure 10. In the figures, the support arm 40 is depicted as a truss structure, but those skilled in the art will appreciate that other configurations are possible. At the outer end of each of the respective support arms 40, a respective turbine module 750 is provided.

In this context, a "turbine module" should be understood to mean a module comprising the following components: one or more turbines 400, a machine housing 752, the machine housing 752 possibly with shafts, hubs, pitch control systems, etc. for connection to the turbines and other contents as needed to generate energy from the water flow.

The turbine 400 may include one, two, three, or more individual turbine blades, as will be understood by those skilled in the art. Hereinafter, "turbine" will be used as a common designation regardless of the number of turbine blades.

Fig. 1, 3 and 4 show that the turbine module 750 has two turbines 400, preferably arranged one at each end of each machine housing 752. In this configuration, the two turbines may be arranged so that they are counter-rotating.

Depending on the generator solution chosen, the machine housing 752 may contain, among other things, hydraulic turbines (pumps) that operate respective hydro-generators via cables. The generator may be located, for example, in the tower 20 or underwater structure 10. In another variation, the machine housing 752 may contain a conventional generator that generates electrical energy by rotating in a manner known to those skilled in the art. In another variation, the machine housing 752 may contain a counter-rotating generator, for example, as described in norwegian patent application 20020800.

The tower 20 is illustrated as a substantially tubular element with a tapered portion 22, the tapered portion 22 being oppositely oriented along the longitudinal axis of the apparatus. But other tower cross-sectional shapes (e.g., oval, rectangular) and configurations (e.g., truss structures) are also considered to be encompassed by the present invention if they perform similar functions. The tapered portions 22 have a drag reducing effect when the apparatus is subjected to water currents, and in addition they will help to repel objects drifting against the apparatus.

Fig. 1 shows an embodiment of the invention in which a subsea structure 10 is provided with a keel 14. The keel 14 may advantageously be provided with additional weight. The underwater structure 10 may also be equipped with stabilizers 12, as shown in fig. 1 and 4, the stabilizers 12 being arranged in pairs at respective ends of the structure 10. Stabilizer 12 may be fixedly or rotatably mounted to structure 10. The keel 14 and stabilizer are not shown in figures 2 and 3.

When the apparatus is in water, it may be anchored to, for example, the seabed via a chain (or cable, cable or rope; hereinafter: mooring cable), which is attached to the apparatus in a manner known per se. In this figure, mooring lines 24a, 24b are attached to respective ends of the underwater structure 10. Fig. 1, 3, 4 show the components of the mooring lines 24a, 24 b. For clarity of illustration, further details regarding handling and locking the mooring lines to the apparatus are omitted as they are known in the art. In the same way, the attachment points for the cables for outputting power and controlling the device are omitted, since these tasks are performed in a manner well known to the person skilled in the art.

The underwater structure 10 and the tower 20 preferably contain ballast tanks (not shown) so that the lifting, lowering and positioning of the apparatus can be controlled by means of ballasting and de-ballasting the tanks.

As shown, the support arm 40 is preferably mounted approximately perpendicular relative to the underwater structure 10. Although this is a preferred arrangement, the invention should not be limited to a strict perpendicular relationship between the support arm and the underwater structure. Those skilled in the art will appreciate that the support arms may also be mounted in a moderate dihedral configuration; this may reduce the need to tilt the apparatus when the underwater structure 10 is lifted to or above the water surface S during use. However, this would require greater strength in the support arms and additional buoyancy capability in the apparatus in order to lift the turbine module above the water surface S.

Referring now to fig. 5, a new anchoring system for equipment when located in water is shown. The apparatus 10, 20 is shown in an operating condition in which the underwater structure 10 is submerged and the tower 20 projects partially above the water surface S.

The mooring systems 24a, 24b are connected at their first ends to respective ends of the underwater structure 10, as mentioned above. The respective second ends of the mooring lines 24a, 24b are connected to separate buoys 50, 52, both buoys 50, 52 being shown floating in the water surface S. The buoy is anchored to the seabed B by means of lower mooring cables 26a, 26B, 26c connected to respective anchors 29a, 29B, 19 c. As shown in fig. 5, the mooring lines 24a, 24b may advantageously be connected to buoys 50, 51 via suitable connection points 27a, 27c, 27d and a suitable length of line 28. In this way, the respective second ends of the mooring lines 24a, 24b are connected to the connection points 27a, 27b, 27c, 27d at a height below the water level S, which height substantially corresponds to the height below the water surface S where the first ends of the mooring lines 24a, 24b are connected to the underwater structure 10.

Such an anchoring system ensures that the mooring lines 24a, 24b extend in a manner that is as horizontal as possible in the water. The apparatus 10, 20 is thus subjected to a substantially horizontal tensile load and the apparatus remains in a position in the water which is as horizontal as possible. Thereby avoiding the vertical force component that would normally be experienced with conventional anchoring. In combination with the proper shape of the tower 10, such an anchoring system helps to reduce pitching of the equipment in water, even in heavy seas.

A key aspect of the proposed buoy anchoring system is that the anchor lines holding the device in place when the device is in operation (e.g. in order to generate a load/resistance of about 160 to 180 tonnes of static load plus additional dynamic load) do not impart a substantial vertical load component to the device 10, 20. For example, a tension of about 200 tons in the mooring lines 24a, 24b, and an angle of about 20 degrees between the lower mooring line 26a or 26b, 26c and the seabed, and a total mooring line length of about 150 meters would require about 70 tons of buoyancy to be generated in the buoy. For example, the buoys 50, 52 may be designed to have a buoyancy of 70 tons as they penetrate the water surface S. Furthermore, it is important to note that the buoy always has about the same buoyancy, even if it sinks, for example, 3 meters below the water surface S. But if this happens, for example when the force increases beyond the assumed maximum, the angle between the mooring line into the plant and down to the bottom B will be reduced at the same time, possibly to about 16 degrees. Thereby, the need for buoyancy in the buoy is also reduced to about 60 tons. Provided there is a distance of about 100 meters between the apparatus and the buoy, the angle into the apparatus will change by only about 1.25 degrees. Thus, the system is unique in that the buoyancy requirement in the buoy decreases as the angle decreases.

Figure 6 shows a series of series arrangements as shown in figure 5 connected together in a row. The apparatus 10 ', 20' is installed in series upstream or downstream of the apparatus 10, 20 described above. The apparatus 10 ', 20 ' is connected to the lower mooring line 26b ' via mooring line 24a ' and the anchor 29b ' is connected to the buoy 52 via connection point 27 a. On the left side of the apparatus 10, 20, the mooring line 24b "indicates that the corresponding apparatus is mounted on the left side of the apparatus 10, 20. In this way, several devices can be connected in series with at least one buoy on each side of each device and at least one anchor in each direction. Alternatively, several anchors are used in each direction out of the buoy. This will result in less lateral drift.

Alternatively, several power plants in a row may incorporate only one buoy between the power plants, which reverses approximately every six hours due to the tension only present in the flow direction. In order to avoid that the mooring lines rub against each other in such a device, it is desirable to use only one anchor in one direction, and possibly two anchors in the other direction. See perspective.

As mooring lines, a combination of chains, steel wires and artificial fibre ropes may be used.

1. A floating installation for generating electrical energy from a flow of water in a body of water, comprising a first element (10), a second element (20) and a plurality of turbine modules (750) connected to the first element,

characterised in that the first element and the turbine module are adapted to be submerged below a water surface, and the second element is mounted on the first element and extends upwardly from the first element when the first element is in a submerged condition, and an upper portion of the second element protrudes above the water surface when the apparatus is in operation.

2. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

characterized in that said first element is provided with a ballast tank.

3. The apparatus of claim 1 or 2,

characterized in that the first element is provided with a keel (14).

4. The apparatus of claim 1, 2 or 3,

the first element is provided with a stabilizer (12), preferably at both ends of the first element.

5. The device of any one of claims 1 to 4,

characterized in that the turbine module (750) is connected to the first element (10) via a respective support arm (40).

6. Anchoring device for a floating installation (10, 20), comprising at least one generator (750) for generating electrical energy and mooring cables (24a, 24b), said mooring cables (24a, 24b) being connected at one of their respective ends to the installation,

characterized in that the mooring lines (24a, 24B) are connected at their respective second ends to buoys (50, 52), the buoys (50, 52) are connected to a bottom (B) below a body of water and are adapted to float in the body of water, and that the second ends of the mooring lines (24a, 24B) are connected to the respective buoys (50, 52) at a height in the body of water corresponding to the height in the body of water at which the first ends of the mooring lines (24a, 24B) are connected to a floating installation (10), whereby the mooring lines (24a, 24B) extend substantially horizontally in the body of water.

7. An anchoring arrangement according to claim 6, wherein the mooring lines (24a, 24b) second ends are connected to the respective buoys via respective connection points (27a, 27b, 27c 527 d) and lines (28) in the body of water.

8. An anchoring device as claimed in claim 6 or 7, wherein the mooring lines (24a, 24b) transmit a substantially horizontal tension load when the apparatus is installed in the body of water.

9. Anchoring device according to any of claims 6-8, characterized in that the buoys (50, 52) are connected via mooring lines (26a, 26B, 26c) to respective anchors (29a, 29B, 29c) on a bottom (B) below the water surface.

10. Anchoring device according to any one of claims 6-9, characterized in that the anchoring cables (24a, 24b) comprise synthetic fiber ropes.

Claims (7)

1. An apparatus for generating energy from a water flow, comprising a first element (10), a second element (20) and a plurality of turbine modules (750) connected to the first element,

characterised in that the second element is mounted in an approximately vertical relationship to the first element, the first element being adapted to be submerged below the water surface and the upper part of the second element protruding above the water surface when the apparatus is in production.

2. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

characterized in that said first element is provided with a ballast tank.

3. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

characterized in that the first element is provided with a keel (14).

4. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

characterized in that the first element is provided with stabilizers (12), preferably at both ends of the first element.

5. The apparatus of claim 1, wherein the first and second electrodes are disposed on opposite sides of the housing,

characterized in that the turbine module (750) is connected to the first element (10) via a respective support arm (40).

6. An anchoring arrangement for a floating plant (10, 20) comprising mooring cables (24a, 24b), said mooring cables (24a, 24b) being connected at one of their respective ends to the plant,

characterized in that the mooring lines (24a, 24b) are connected at their respective second ends to buoys (50, 52) via respective connection points (27a, 27b, 27c, 27d) below the water surface (S) and lines (28), whereby the mooring lines (24a, 24b) extend substantially horizontally between the plant and the respective buoys.

7. The anchoring device according to claim 6,

characterized in that the buoys (50, 52) are connected via mooring lines (26a, 26B, 26c) to corresponding anchors (29a, 29b, 29c) on a bottom (B) below the water surface.