WO2011025387A1

WO2011025387A1 - Apparatus for extracting tidal and wave energy

Info

Publication number: WO2011025387A1
Application number: PCT/NO2010/000322
Authority: WO
Inventors: Per Kollandsrud
Original assignee: Tidetec As
Priority date: 2009-08-31
Filing date: 2010-08-31
Publication date: 2011-03-03
Also published as: NO20092908A1; NO330474B1

Abstract

An apparatus is described for extracting energy from a flow of water between a first and a second reservoir, where the flowing water has a variable, dominant flow direction. The apparatus comprises a first flow space for flowing water, which communicates with the first reservoir, and a second flow space for flowing water, which communicates with the second reservoir, and a turbine connected to a generator and arranged on a turbine support column between the first and the second flow space, the turbine support column being arranged rotatably about an essentially vertical axis to permit adjustment of the turbine's orientation according to the dominant flow direction of the flowing water. To harness the energy from waves on the surface, in addition to the tidal action, the apparatus further comprises at least one wave collector that is arranged in connection with the surface of the first or second reservoir, at least one accumulation chamber which receives water from the wave collector, and a valve means arranged to allow water from the accumulation chamber to exit into the first or second flow space depending on the dominant flow direction of the flowing water.

Description

APPARATUS FOR EXTRACTING TIDAL AND WAVE ENERGY

FIELD OF THE INVENTION

The present invention relates in general to the extraction of energy from a flow of water between water reservoirs, typically as a result of tidal forces and waves.

More specifically, the invention relates to an apparatus for extracting energy from a flow of water between a first and a second reservoir, where the flowing water has a variable, dominant flow direction, the apparatus comprising a first flow space for flowing water, which communicates with the first reservoir, a second flow space for flowing water, which communicates with the second reservoir, and a turbine connected to a generator and arranged on a turbine support column between the first and the second flow space. The turbine support column is arranged rotatably about an essentially vertical axis to allow adjustment of the turbine's orientation in accordance with the dominant flow direction of the flowing water.

The invention also relates to a method for extracting energy from a flow of water between reservoirs, typically as a result of tidal forces.

BACKGROUND OF THE INVENTION

The global community is facing major climate changes, and one important challenge is to replace fossil fuels with renewable energy sources, such as tidal power and wave power.

An apparatus as mentioned above is previously known from WO-2005/017349. This document teaches an apparatus for generating energy from a flow of water as a result of tidal forces. The apparatus comprises a turbine connected to a generator, and a first and a second flow space for flowing water, which are located on their respective side of the turbine. The turbine is rotatably arranged about a vertical axis. The position of the turbine is adjusted depending on the direction of flow prevailing at any given time between the first and the second flow space.

US-4 521 152 teaches a solution for extracting kinetic energy from water surface waves, based on an inclined, partially submerged wave collector. At the upper portion of the wave collector there is provided an outlet which can be connected to an energy transformer.

SUMMARY OF THE INVENTION

A general object of the invention is to provide an apparatus as mentioned by way of introduction, and which in addition harnesses the kinetic energy inherent in the water surface waves. According to the invention there is provided an apparatus as disclosed in

independent claim 1 below.

According to the invention there is also provided a method as disclosed in independent claim 11 below.

Advantageous embodiments and additional features are disclosed in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In what follows, the invention will be described in more detail as a non-limiting example, illustrated in the appended drawings and explained in the following detailed description. Where possible, identical or corresponding elements have been indicated by means of the same reference designations in the drawings.

Fig. 1 is a schematic perspective view illustrating principles of the construction of a water barrier;

Fig 2 is a schematic side view of an apparatus according to the invention in a first use scenario;

Fig. 3 is a schematic side view of an apparatus according to the invention in a second use scenario;

Fig. 4 is a schematic side view of an apparatus according to the invention in a third use scenario;

Fig. 5 is a schematic side view of an apparatus according to the invention in a fourth use scenario;

Fig. 6 is a schematic front view of a turbine support column with a valve element; Fig. 7 is a schematic side view of the turbine support column shown in Fig. 6;

Fig. 8 is a schematic view of the turbine support column shown in Fig. 6, seen from above;

Fig. 9 is a schematic cross-sectional view of the turbine support column shown in Fig. 6 taken along the line A-A;

Fig. 10 is a schematic side view of an alternative embodiment of an apparatus according to the invention;

Fig. 11 is a schematic view of a turbine support column with valve element for use with the alternative embodiment shown in Fig. 10.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 is a schematic perspective view illustrating principles of the construction of a water barrier, in which an apparatus according to the invention is incorporated. The present apparatus and method are particularly useful in locations where the tide water causes substantial water currents, typically in narrow and shallow sounds. An example of a sound 1 is illustrated in Fig. 1.

In such a location, the apparatus may be made as a part of a water barrier which wholly or partly constitutes an obstruction between the first reservoir 10 on one side of the sound 1 and the second reservoir 20 on the other side of the sound 1. An example of such a water barrier may be a barrage or dam which essentially blocks off water across the whole cross-section of the sound, with the exception of through-flow areas in the barrier, where turbines may be arranged for harnessing the water flow. However, in this document water barriers should also be understood to mean structures which only partly constitute an obstruction to flowing water. Other examples of water barriers may therefore be a breakwater, a partly submerged bridge, or the like. Although Figure 1 illustrates the construction of a water barrier between parts of the mainland, it should be understood that a water barrier may alternatively be provided between a mainland area and an island or between islands.

As illustrated in Fig. 1 , a water barrier can be constructed by deploying a plurality of floating structural elements 2, which may be prefabricated, for example, in a dry dock. The construction material for the elements 2 may primarily be concrete. The structural elements 2 can be towed out to the installation site with the aid of a vessel 3. At the installation site, the structural elements 2 can be anchored to the bottom, preferably to solid rock, and/or to each other. Figure 1 shows a situation where seven elements have already been deployed and assembled/anchored, whilst an eighth element 2 is being towed into place.

An apparatus for extracting energy according to the invention is incorporated in at least one of the structural elements 2. It will be understood that all the structural elements 2 may comprise an apparatus according to the invention, or just one of the structural elements is made thus, whilst other structural elements have a different configuration, for example, made in the form of pure barrier elements.

The activity illustrated in Fig. 1 is therefore an example of a method for achieving energy extraction from a flow of water between a first and a second reservoir, where the flowing water has a variable, dominant direction of flow between the first and the second reservoir, the method comprising providing a water barrier between the first and second reservoir, the water barrier comprising at least one apparatus as described, inter alia, with reference to Fig. 2 below.

Fig. 2 is a schematic side view of an apparatus 4 for extracting energy from a flow of water between a first 10 and a second 20 reservoir, where the flowing water has a variable, dominant flow direction. Such variable, dominant flow direction may be due to tidal forces. The apparatus 4 comprises a first flow space 12 for flowing water, which

communicates with the first reservoir 10, and a second flow space 22 for flowing water, which communicates with the second reservoir 20.

The first 12 and the second 22 flow space are generally configured as axially open pipes, for example, conical or trumpet-shaped, and are arranged to collect water that flows from respectively the first reservoir 10 or the second reservoir 20, for example, as a result of tidal forces. The arrows in Fig. 2 indicate a direction of flow from the second reservoir 20 to the first reservoir 10.

Fig. 2 also shows surface waves on the water, which are especially pronounced on the right-hand side, i.e., the side corresponding to the second reservoir 20.

It should be understood that the dominant direction of the flow that is due to tidal forces will be variable. More specifically, the direction will alternately adopt one direction or the other as a result of tidal forces.

The degree of surface waves, i.e., the wave height, depends in particular on the wind conditions, and is to a lesser extent dependent upon the tide. As will be explained below, an embodiment of the apparatus will be especially suitable for harnessing all existing combinations of dominant flow directions and wave occurrences.

In an embodiment, each of the flow spaces 12, 22 is wholly or substantially circular in cross-section. Alternatively, one of them, or both, may have a wholly or substantially circular cross-section at their inner portion, that is to say, closest to the turbine 30, and any, but larger cross-section, for example, rectangular or square, at their outer portion, that is to say, the area facing the respective reservoir 10, 20. The flow spaces 12, 22 are defined by partly surrounding walls, typically made of a cast, solid and robust construction material such as concrete.

The apparatus 4 further comprises a turbine 30, which is connected to a generator 50, via a connecting element such as a shaft.

The turbine 30 is arranged on a turbine support column 36 which is located between the first flow space 12 and the second flow space 22. The turbine support column 36 is arranged rotatably about an essentially vertical axis 38 to permit adjustment of the turbine's orientation in accordance with the dominant flow direction of the flowing water.

The turbine 30 is a water turbine, for example, of the reaction turbine type, such as a propeller turbine. The turbine 30 may be of a type that has flow direction dependent efficiency. The turbine 30 comprises a plurality of turbine blades 32, for example, three or four, which are attached to an essentially horizontal turbine shaft. The turbine 30 may be mounted on a support column. The orientation of the turbine 30 may therefore be adjusted depending on the direction of flow between the first 10 and the second 20 reservoir. For this purpose, the turbine support column 36, at its lower end, is rotationally supported in a base structure. The apparatus further comprises rotating means (illustrated at 52, 54, 56 in Fig. 8) which permit 180° rotation of the turbine support column 36, and thus the turbine 30, about the vertical axis.

In order to be able, in addition, to harness the energy in the water surface waves, the apparatus further comprises, in the form in which it is illustrated, a first wave collector 60 and a second wave collector 70, each of these wave collectors being arranged in connection with the surface of respectively the first reservoir 10 and the second reservoir 20.

Each of the wave collectors 60, 70 may comprise partly submerged inclined planes. It is a function of the wave collectors to collect water from incident waves on the surface of the reservoirs 10, 20.

It will be understood that the apparatus 4 will also be capable of being used with just one wave collector, or more than two wave collectors.

The apparatus 4 further comprises at least one accumulation chamber 80 which receives water from the at least one wave collector, or as illustrated, the two wave collectors 60, 70.

The accumulation chamber 80 is traversed by a wholly or essentially vertical passage, in the form of, for example, a cylindrical, vertical concrete structure, which provides space for the turbine support column 36 and the connecting element which runs along the axis 38 between the turbine 30 and the generator 50. This opening also provides space for the assembly and dismantling of the whole turbine. In an embodiment, the at least one accumulation chamber 80 is a common accumulation chamber for accumulating water received from the first 60 and the second 70 wave collector. The common accumulation chamber 80 is obtained by allowing there to be an open fluid connection between the two parts of the accumulation chamber as shown on respectively the left-hand and the right-hand side of the rotational shaft 38 of the turbine in Fig. 1. To show that the

accumulation chamber is in reality one and the same chamber, or that they are in fluid correspondence, the reference designation 80 is used on both the left-hand and the right-hand side of the vertical turbine support column 36.

In the illustrated embodiment, between the first wave collector 60 and the accumulation chamber 80 there is provided a non-return valve 62, arranged to allow water into the accumulation chamber and at the same time prevent water from flowing back from the accumulation chamber and into the first reservoir 10.

Similarly, between the second wave collector 70 and the accumulation chamber 80 there is provided a non-return valve 72, arranged to allow water into the accumulation chamber and at the same time prevent water from flowing back from the accumulation chamber and into the second reservoir 20.

For this purpose, each of the non-return valves 62, 72 can be made as a top-hinged flap, for example, freely suspended. The flaps are specifically arranged to allow one-way flow of water into the accumulation chamber 80, as they are only able to swing inwards towards the interior of the accumulation chamber 80.

It will be understood that one or both non-return valves 62, 72 may alternatively be omitted, as they provide an advantageous extra effect, but are not essential for the principle of the invention.

In an alternative embodiment, the at least one accumulation chamber comprises a first accumulation chamber for accumulating water received from the first wave collector 60 and a second accumulation chamber for accumulating water received from the second wave collector 70. This can be obtained by allowing the two parts of the accumulation chamber that are shown on respectively the left-hand side and the right-hand side of the rotational shaft 38 of the turbine in Fig. 1 to be fluid- separated by, for example, a wall.

The apparatus 4 further comprises a valve means, which is adapted to allow water from the accumulation chamber 80 into the first flow space 12 or the second flow space 22, depending on the dominant flow direction of the flowing water.

In the illustrated embodiment, the valve means comprises a valve element 40 which is rotatable about the rotational axis of the turbine support housing 36.

More specifically, the valve element 40 is configured as an essentially vertical passage through a section of the turbine support column 36.

In an embodiment, the valve means 40 which traverses the turbine support column comprises an outlet 42 with an orientation that follows the turning of the turbine support column 36. In the embodiment in Figure 2, the outlet 42 is configured on the same side as the outlet side of the turbine.

In the case that the accumulation chamber 80 contains water, and the valve means ensures an open connection down to the valve outlet 42 and onwards through the first intermediate chamber 82 and then to the outlet 83, an additional water flow is passed by the force of gravity into the first flow space 12. This additional water flow contributes to increased water velocity and water volume that is drawn through the turbine 30, and thus the energy from the water surface waves is harnessed in addition to the power of the tide. The outlet 83 is arranged sloping downwards, and almost horizontal, in such a way that the water passed from the first intermediate chamber 82 and then out of the outlet 83, is passed almost in the same direction as the dominant direction of flow, that is to say, towards the reservoir 10. It will be understood that the outlet 83 may comprise one pipe, channel or other form of passage, or several such pipes, channels or passages, arranged, for example, adjacent to each other.

In an embodiment, the turbine support column is adapted to be turned controllably according to a control signal that is activated by a flow detector and/or prior knowledge of periodic tidal variations.

It will be understood that the apparatus 4 is especially useful as a structural element 2 in a water barrier as mentioned above.

To determine the dominant direction of flow, in one instance there may be provided a flow direction detector (not shown) at a point in the first flow space or the second flow space. In another instance, to further ensure a reliable indication of the dominant direction of flow, a number of flow direction detectors may be provided at different points in the first and/or second flow space, and a control device may be configured to determine the dominant direction of flow on the basis of signals emitted from such flow direction detectors.

Alternatively, the control device may be adapted to predict or compute the dominant flow direction on the basis of time data provided by a running clock contained within the control device and pre-stored astronomical-geographical data, in particular tide data for the location in question, contained in a memory in the control device.

In this way, prior knowledge of periodic tidal variations, and thus the flow direction prevailing at any given time, can effect control of the turning of the turbine support column (and thus the turbine), and the valve device 40. In this way, the use of sensors/detectors and possible sources of error, wear, defects and/or maintenance can be avoided or reduced. On the other hand, control based exclusively on pre- stored tide data does not take into account special conditions of a non-deterministic nature, for example, meteorological phenomena such as high storm water.

In any of the aforementioned embodiments, the said control device may be configured as an electronic control unit, comprising a controller with a

microprocessor and controlled by a set of processor instructions contained within a memory or storage. The microprocessor may be connected to necessary input-output units for inputting detector/sensor data and outputting generated control data for controlling the drive means used to turn the turbine support column, and thus the valve device.

In the first use scenario in Figure 2, the tidal current has a direction towards the left-hand side of the drawing, from the second reservoir 20 towards the first reservoir 10. Furthermore, there are wind and wave conditions that are dominant on the side corresponding to the second reservoir 20. The waves therefore cause water to enter the accumulation chamber 80 via the second wave collector 70. The direction of the tidal current causes the turbine to be turned to the left, that is to say, in towards the first flow space 12. The turning of the turbine support column 36 into this orientation also causes the valve device 40 to provide open communication from the accumulation chamber 80 to the first flow space 12. This contributes to a gain in the water velocity and water volume that are drawn through the turbine 30.

Fig. 3 is a schematic side view of an apparatus according to the invention in a second use scenario.

In this case, the tidal current has a direction towards the left of the drawing, from the second reservoir 20 towards the first reservoir 10. There are also wind and wave conditions that are dominant on the side corresponding to the first reservoir 10. The waves therefore cause water to enter the accumulation chamber 80 via the first wave collector 60.

The direction of the tidal current also in this case causes the turbine to be turned towards the left, that is to say, in towards the first flow space 12. The turning of the turbine support column 36 into this orientation causes the valve device 40 to provide open communication from the accumulation chamber 80 to the first flow space 12 via the outlet 83. This contributes to a gain in the water velocity and water volume that are drawn through the turbine 30.

Fig. 4 is a schematic side view of an apparatus according to the invention in a third use scenario.

In this case, the tidal current has a direction towards the right of the drawing, from the first reservoir 10 towards the second reservoir 20. Furthermore, there are wind and wave conditions that are dominant on the side corresponding to the first reservoir 10. The waves therefore cause water to enter the accumulation chamber 80 via the first wave collector 60.

The direction of the tidal current here causes the turbine to be turned towards the right, that is to say, in towards the second flow space 22. The turning of the turbine support column 36 into this orientation causes the valve device 40 to provide open communication from the accumulation chamber 80 to the second flow space 22 via the second intermediate chamber 84 and then via the outlet 85, which is arranged sloping downwards, substantially horizontally, and in a direction that essentially coincides with the direction of the dominant flow direction, that is to say, towards the second reservoir 20. This contributes, also in this case, to a gain in the water velocity and water volume that are drawn through the turbine 30. It will be understood that the outlet 85, like the outlet 83, may comprise one pipe or other form of channel or passage, or several such pipes, channels or passages, arranged, for example, adjacent to each other.

It will be understood that the first 82 intermediate chamber and the second 84 intermediate chamber are separated. Fig. 5 is a schematic side view of an apparatus according to the invention in a fourth use scenario.

In this case, the tidal current has a direction towards the right of the drawing, from the first reservoir 10 towards the second reservoir 20. There are also wind and wave conditions which are dominant on the side corresponding to the second reservoir 10. The waves therefore cause water to enter the accumulation chamber 80 via the second wave collector 70.

The direction of the tidal current in this case causes the turbine to be turned to the right, that is to say, in towards the second flow space 22. The turning of the turbine support column 36 into this orientation causes the valve device 40 to provide open communication from the accumulation chamber 80 to the second flow space 22 via the outlet 85. This contributes, also in this case, to a gain in the water velocity and water volume that are drawn through the turbine 30.

As will be understood from Figures 2-5, the apparatus will result in an especially advantageous harnessing of energy that is due to both tide and waves, in all the illustrated cases.

Fig. 6 is a schematic front view of a turbine support column with a valve element, and Fig. 7 is a schematic side view of the turbine support column shown in Fig. 6.

The turbine support column 36, at its lower portion, comprises the turbine 30 that is arranged on the same side as the valve element 40, which is configured as an essentially vertical passage through a section of the turbine support column 36. At the bottom, the turbine support column 36 is provided with means for rotatable support in a subjacent base structure.

Fig. 8 is a schematic view of the turbine support column shown in Fig. 6 seen from above. This figure shows rotating means (illustrated at 52, 54, 56 in Fig. 8) which permit rotation of the turbine support column 36, and thus the turbine 30, about the vertical axis.

Fig. 9 is a schematic cross-sectional view of the turbine support column shown in Fig. 6 taken through the line A-A, the hatched area showing an almost semi- circular, hatched cross-section that corresponds to the material of the turbine support column, whilst the almost semi-circular non-hatched cross-section corresponds to the open area that is constituted by the essentially vertical passage which is a part of the valve means 40.

Fig. 10 is a schematic side view of an alternative embodiment of an apparatus according to the invention.

The apparatus 4 corresponds essentially to the apparatus illustrated in Figs. 2-5, with the following exceptions: The apparatus illustrated in Figs. 2-5 is provided with an outlet 83 arranged almost horizontally, in such a way that the water passed from the first intermediate chamber 82 and out of the outlet 83, is passed towards the first reservoir 10, and an outlet 85, also arranged almost horizontally, such that the water passed from the second intermediate chamber 84 and out of the outlet 83, is passed towards the second reservoir 20. In both cases, the outlets 83, 85 are arranged having a direction away from the turbine 30. In the alternative embodiment in Fig. 8 the configuration is identical, but the outlets 83', 85' are instead directed at an angle down towards the turbine. At the same time, the turbine is arranged on the opposite side of the turbine support column, that is to say, the opposite side of the passage through a section of the turbine support column that forms the valve element 40.

Fig. 11 is a schematic view of a turbine support column with valve element for use with the alternative embodiment shown in Fig. 10. Here it can be seen that the turbine 30 is arranged opposite (offset 180 degrees in relation to) the valve element 40, configured as an essentially vertical passage through a section of the turbine support column 36.

It will be understood that the above description is given in the form of non-limiting, illustrative examples. Many variations and alternatives will be apparent to those of skill in the art. The principle and scope of the invention are therefore defined by the claims below and their equivalents.

Claims

PATENT CLAIMS

1. An apparatus for extracting energy from a flow of water between a first and a second reservoir, where the flowing water has a variable, dominant flow direction, the apparatus comprising:

- a first flow space for flowing water, which communicates with the first reservoir; and

a second flow space for flowing water, which communicates with the second reservoir;

a turbine connected to a generator and arranged on a turbine support column between the first and the second flow space, the turbine support column being arranged rotatably about an essentially vertical axis to permit adjustment of the turbine's orientation according to the dominant flow direction of the flowing water, c h a r a c t e r i s e d i n that the apparatus further comprises:

at least one wave collector, arranged in connection with the surface of the first or second reservoir;

an accumulation chamber which receives water from the wave collector; and a valve means adapted to allow water from the accumulation chamber to exit into the first or second flow space according to the dominant flow direction of the flowing water.

2. An apparatus according to claim 1,

wherein the valve means comprises a valve element that is rotatable about the rotational axis of the turbine support column.

3. An apparatus according to claim 2,

wherein the valve element comprises an essentially vertical passage through a section of the turbine support column.

4. An apparatus according to one of claims 1-3,

wherein the valve means comprises an outlet which has an orientation that follows the turning of the turbine support column.

5. An apparatus according to one of claims 1-4,

wherein the at least one wave collector comprises:

a first wave collector arranged in connection with the surface of the first reservoir; and

a second wave collector arranged in connection with the surface of the second reservoir.

6. An apparatus according to claim 5,

wherein the accumulation chamber is common to the first and second wave collector.

7. An apparatus according to one of claims 5-6,

wherein the said first and second wave collectors comprise partly submerged inclined planes.

8. An apparatus according to one of claims 1-7,

wherein the turbine support column is adapted to be turned controllably according to a control signal that is activated by a flow detector and /or prior knowledge of periodic tidal variations.

9. An apparatus according to one of claims 1-8,

configured as a structural element of a water barrier.

10. An apparatus according to one of claims 1-9,

further comprising a non-return valve arranged between the at least one wave collector and the accumulation chamber.

11. A method for extracting energy from a flow of water between a first and a second reservoir, where the flowing water has a variable, dominant direction of flow between the first and second reservoir,

the method comprising providing a water barrier between the first and second reservoir,

c h a r a c t e r i s e d i n that the water barrier comprises at least one apparatus according to one of claims 1-11.