WO1993015315A1

WO1993015315A1 - Power generation, preferably by utilisation of wave energy

Info

Publication number: WO1993015315A1
Application number: PCT/GB1993/000190
Authority: WO
Inventors: Francis Norman Potter
Original assignee: Francis Norman Potter
Priority date: 1992-01-28
Filing date: 1993-01-28
Publication date: 1993-08-05
Also published as: AU3456193A

Abstract

Apparatus for power generation preferably by utilisation of wave energy comprises a chamber (11) which is arranged to be supported so as to change its orientation in response to a natural influence, e.g. by being floated on a body of water. The chamber contains a liquid which flows between different parts of the chamber as its attitude changes, and power generating means e.g. a turbine (18) driven by the flowing liquid.

Description

Title: "Power generation, preferably by utilisation of wave energy" Description of the Invention

This invention relates to power generation by utilisation of wave energy, or possibly by utilisation of wind energy.

There have been various proposals for the generation of power, particularly electrical power, by making use of the motion which waves on the surface of a body of water impose on an object floating on the water. It is the object of the present invention to provide an improved means for such utilisation of wave energy.

According to one aspect of the present invention, I provide apparatus comprising means defining a chamber adapted to be supported in such a way as to change its attitude in response to a natural influence thereon, and containing a liquid which is able to flow between different parts of the chamber in consequence of said attitude change; and power generating means drivable by said liquid in the course of its flowing between the different parts of the chamber.

The chamber is preferably adapted to float on a body of water so that the liquid flows between different parts of the chamber when the chamber changes its attitude as a result of being affected by waves on the surface of the water. However, it would be within the scope of the invention for the chamber to be arranged to respond to the influence of the other major natural energy resource, i.e. the wind, by changing its attitude.

Preferably the chamber is of elongate configuration, having floatation means at its opposite ends and adapted to undergo a pitching motion under the influence of waves.

When such apparatus is floated on the surface of the body of water which has waves, the pitching motion will cause a substantial flow of the liquid between opposite ends of the chamber. Such flow of liquid may be used to drive a power generating means and thus convert some of the energy present in the body of water by virtue of the wave motion thereon into usable power.

Preferably the power generating means is a rotary device or devices, drivable by the flowing liquid and having a mechanical output which may be connected to an electrical generator or generators.

The power generating means may comprise at least one device disposed at a position between the ends of the chamber, preferably approximately mid-way therebetween.

The power generating means may comprise at least one axial flow turbine device, having blades disposed about a shaft extending generally lengthwise of the chamber.

As an alternative or addition to the provision of power generating means between the ends of the chamber, power generating means may be provided at or adjacent one or both ends of the chamber, to be driven by the liquid in the course of reversal of its direction of flow which occurs at such ends of the chamber.

There may further be provided power generating means arranged to be driven by the flow of air in the chamber which occurs in the opposite direction to the flow of liquid therein.

Conveniently the liquid in the chamber is water, so that the quantity of liquid in the chamber may be added to or reduced by providing appropriate communication with the body of water on which the apparatus is floating.

A turbine drivable by the flow of liquid may comprise blades mounted relative to the shaft of the turbine in such a way as to be able to orientate themselves automatically in response to the flow of liquid, so that whichever direction the liquid is flowing, the shaft is caused to rotate in one direction only. This eliminates the need to provide any means for dealing with a reversal of the direction of shaft rotation, and reduces the power losses which would take place if a shaft had to be repeatedly brought to a halt and then its rotation restarted in the opposite direction. Preferably the blades are also able to orientate themselves to assume an inclination or pitch dependent on the rate of flow of liquid past them. In rough weather conditions, when the apparatus will tilt to relatively large angles, and the liquid flow in the chamber is consequently relatively great, the ability of the turbine blades to adjust themselves to a coarse pitch will prevent excessive stress on the blades and turbine bearings, and also improve efficiency.

The chamber may have a greater cross-sectional area at its ends than at a position between its ends, so that the amount of liquid contained in the chamber as a whole can be increased, and the flow thereof through at least one turbine between the ends of the chamber can be arranged to provide for a more efficient generation of power.

The invention will now be described by way of example with reference to the accompanying drawings, of which:

FIGURES 1 and 2 are respectively a side elevation and plan of a first embodiment of the apparatus according to the invention;

FIGURE 3 is an elevation showing the mode of operation of the apparatus of Figures 1 and 2;

FIGURE 4 is a detail showing part of a turbine forming part of the apparatus;

FIGURES 5 and 6 are respectively a side elevation and plan of a further embodiment of apparatus according to the invention;

FIGURE 7 is a side elevation of yet a further embodiment of apparatus according to the invention;

FIGURE 8 is a perspective view of part of a turbine of the apparatus.

FIGURES 9, 10, 11 are diagrammatic side elevations of parts of further embodiments of apparatus according to the invention;

FIGURES 12 and 13 are diagrammatic plan views of further embodiments of apparatus according to the invention;

FIGURES 14 and 15 are respectively a plan and elevation of a configuration of float which may be used in the invention; FIGURES 16 and 17 are respectively a diagrammatic plan and elevation of a further embodiment of apparatus according to the invention;

FIGURE 18 is a diagrammatic elevation of a further possible configuration of apparatus according to the invention;

FIGURES 19, 20 and 21 are respectively a front elevation, plan and side elevation of another embodiment of apparatus according to the invention.

Referring firstly to Figures 1 and 2 of the drawings, the apparatus there illustrated comprises a casing 10 of elongate configuration, defining an internal chamber 11. The casing 10 is closed at its ends by covers 12, and at its ends there are provided floatation devices 13 which may comprise sealed casings containing air. A shaft 14 extends lengthwise through the chamber 11, being supported in bearings 15 at the end covers 12 of the chamber and further bearings 16 in intermediate supports 17 between the ends of the chamber.

Mid-way between the ends of the chamber, the shaft 14 carries a turbine indicated generally at 18 in Figures 1 and 2. A quantity of liquid, preferably water, is contained in the chamber 11 and the turbine 18 is arranged to be driven by such flow of liquid between opposite ends of the chamber when the chamber tilts. At one or both ends of the chamber, in the position indicated at 19, there may be provided a flywheel and an electrical generator.

In use, the apparatus shown in Figures 1 and 2 will be floated on a body of water which usually has waves on its surface, and tethered in such a way as to meet such waves and undergo a pitching motion in response thereto. Figure 3 shows the apparatus in such a situation, with the float 13 at one end of the chamber about to meet a wave crest and the float at the other end of the chamber in the trough between adjacent wave crests. The tilted orientation assumed by the chamber as part of the pitching motion it undergoes in meeting successive waves causes the liquid in the chamber, whose surface is indicated at 21 in Figure 3, to flow from one end of the chamber to the other and drive the turbine 18 in the course of such flow. When the first float 13 is subsequently at the crest of a wave and the other float in a trough, the chamber is tilted oppositely from the orientation illustrated and the liquid flows back in the opposite direction.

The principal of construction and operation of the turbine which is indicated generally at 18 in Figures 1 and 2 is shown in greater detail in Figures 4 and 8. In these figures is shown the shaft 14 which carries a hub 23 which supports a number of radially extending, equally circumferentially spaced, shafts 24 carrying respective blades 25. These shafts are pivo table about their respective axes, relative to the hub 23, so that the blades 25 are able to change their orientation. The hub 23 and radially innermost parts of the shaft 24 lie between a pair of oppositely oriented frusto-conical members 26 which are each movable axially of the shaft 14 against respective compression springs 27 abutting collars 28 fixed to the shaft. The conical members 26 are engaged by cams 29 carried by the blade-supporting shafts 24, the arrangement being such that as the shafts pivot about their respective axes relative to the hub 23, one or other of the cone shaped members 26 is engaged and pushed against its compression spring 28 to resist such pivoting movement. The arrangement is such that whichever direction flow takes place through the turbine, the blades assume an orientation such that they are caused to be driven in the direction indicated by arrows 30 in Figure 8, so that whenever water flow occurs through the turbine, the shaft 14 is driven in the same direction. Instead of the illustrated arrangement of springs 27, the blades could be provided with individual springs to control their movement.

Furthermore, the above described pivotal support of the blades 25 is such that when flow of water past the turbine takes place at a greater speed, the blades orientate themselves, against the opposition of springs 27, to a coarser pitch so that they, and all the other parts of the turbine, including the shaft 14 and the bearings by which it is supported, are not overloaded as a result of such increased flow of water. The turbine is thus able to cope with relatively calm conditions in which the pitching motion the apparatus undergoes is of only a small magnitude, and much rougher conditions in which a much greater pitching motion is caused. Referring now to Figures 5 and 6 of the drawings, these show a further embodiment of apparatus comprising a casing 40 which, instead of being of substantially constant cross-sectional shape and dimension throughout its length, is of smaller cross-section at a position mid-way between its ends than it is at such ends. A turbine indicated generally at 41, and preferably of the construction described above, is mounted at the position of minimum cross-section of the casing 40, being supported on a shaft 42 carried by bearings 43 in supports 44. At opposite ends of the casing 40 (from which the necessary floats have been omitted in the drawings), there are provided respective power generating devices indicated generally at 45, in the form of bladed wheels rotatable about transverse shafts 46 supported in bearings 47 at the sides of the casing 40, and arranged to be driven by the reversal of flow of water which occurs at the ends of the casing during the pitching motion thereof. The ends of the casing are of part-cylindrical configuration as indicated at 48, to conform closely to the periphery of the wheels 45, and the blades on the wheels are shaped, to ensure most efficient driving of the wheels by the liquid flowing circumferentially thereof.

Referring now to Figure 7 of the drawings, this shows yet a further embodiment of apparatus according to the invention which comprises a casing 60 of substantially constant cross-section throughout its length, having end covers 61. Floats 62 are depicted at the ends of the casings 60. Mid-way between its ends, a turbine indicated generally at 63 is carried by a shaft 64, the shaft being carried in bearings 65 by support members 66 and emerging through the end cover 61 at one end of the casing at which there is a further bearing 67. As above referred to, an electrical generator may be provided on the shaft 64 outside the casing. At the ends of the apparatus there are provided internal flow-directing baffles 68 for directing the flow of water in the course of its change of flow direction in the chamber as the apparatus undergoes a pitching motion, and at the opposite end of the chamber to that at which the shaft 64 emerges there is a further turbine wheel 69 arranged to be driven, as in the embodiment of Figures 5 and 6, by the reversing flow of water within the chamber. In all the above described embodiments, as the water flows from one end of the chamber to the other it will be appreciated that there is a flow of air in the opposite direction to the flow of water. Power-generating means arranged to be driven by such air flow may be provided at suitable positions in the chamber.

It will further be appreciated that means other than the turbines illustrated may be provided to generate power from the flow of water within the chamber caused by the pitching motion thereof in response to the waves on the body of the water on which the apparatus floats.

If provided on or in association with a vessel travelling on water, the power generated by the apparatus could be used for, or to assist in, propulsion of the vessel.

It would be possible for a chamber as one of the embodiments described above to be installed on land, in such a way as to have its orientation changed by the influence of the wind and thus generate power from this natural energy resource.

Yet a further possibility is that a chamber as one of the embodiments described herein could be installed on land in such a way as to have its orientation changed by the influence of waves adjacent the land. For example, a chamber could have one end pivoted to the land and the other end provided with floats on an adjacent stretch of water.

Referring now to Figure 9 of the drawings, this shows a further embodiment in which additional means is provided for generating power from motion of a chamber within which water is caused to flow. Part only of a casing 70 is shown, defining an elongate chamber analogous to the embodiments above described. Midway between its ends, the casing includes a downwardly displaced tunnel portion 71 and baffle arrangement 72 to provide a tunnel portion 73 in which a turbine may be disposed as above described. At each of its ends the casing is provided internally with a flow-directing baffle 74. A pivotal connection 75 is provided to an arm 76 at the free end of which, beyond the end of the casing 70, there is mounted a float 77. Between the arm 76 and casing 70 there is provided a device 78 for power generation, e.g. by a pumping action on a fluid as a result of relative movement between the arms 76 and casing 70. For example the device 78 may comprise a pump for displacing air; a flexible chamber for the same purpose, or any other power generating means which is operable by relative movement between arm and chamber.

Thus the embodiment of Figure 9 provides for additional power generation, beyond that which may be generated in consequence of flow of water in the chamber defined by casing 70 and operable on a turbine as above described.

Referring now to Figure 10 of the drawings, this shows an arrangement of casing 80, tunnel portion 81, flow-directing baffle 82 and turbine shroud 83, all analogous to those shown in Figure 9. A float is not shown in Figure 10. In order to enable the generating of power by conversion of the kinetic energy which water in the chamber possesses as it reaches the ends of the chamber, the flow- directing baffle 84 provided at the chamber end is arranged to be displaceable, e.g. to a position 84a, shown in broken lines in Figure 10. The baffle 84 is connected to a device 85, which may be a pump, flexible chamber, or the like, connected to a power generator, e.g. by pipes, not shown.

Referring now to Figure 11 of the drawings, this illustrates how apparatus in accordance with the invention may be constructed by utilising the hull of a vessel such as a barge to provide the chamber for containing water which may be caused to flow between different parts of the chamber in consequence of wave action. In Figure 11, part of the hull of a barge is indicated at 90 and it will be appreciated that such a hull initially is essentially watertight to enable it to float. The conversion to a water flow chamber for the purposes of the present invention is effected by incorporating in a central portion of the hull downwardly extending structural portions 91, 92 leading to a tunnel portion 93 in which a turbine is disposed. The upper part of the hull is closed by a closure member 94, and a flow-directing baffle member 95 is provided where indicated in broken lines above the bow or stern portion of the hull 96. A float or buoyancy chamber 97 is attached at the end of the hull, and as illustrated an electrical generator 99 is disposed within the float 97 being driven by way of a shaft 98 from the turbine positioned at the centre of the hull.

In the embodiments of Figures 9, 10, and 11, the disposition of a turbine in a part of the chamber having an increased depth of water is advantageous to efficiency of turbine operation.

Referring now to Figure 12 of the drawings, this shows a further embodiment of the invention wherein a configuration of chamber for flow of liquid is used which differs from the relatively long and narrow configuration hereinbefore described. The embodiment of Figure 12 comprises a circular structure indicated generally at 100, which is divided by internal walls into two chambers 101 for containing liquid which is to flow for power generation, and two buoyancy chambers 102 to enable the whole structure to float on water. The chambers 101 are joined by a relatively narrow turbine chamber 103 to define a "figure eight" or "hourglass" shaped chamber. In each of the chambers 101 there is disclosed a flow-control gate 104 with a respective pivot 105; the gates are pivotable between stops as indicated at 106 so as to be able to assume alternative positions as indicated in broken lines at 107. The gates are each spring biased to their one position but are movable against such spring biasing to their other limiting positions when acted on by flow of liquid in a particular sense. A turbine is disposed within the turbine chamber 103, and a shaft 108 connects to a generator 109.

The effect of the arrangement of the flow-control gates is such that when the device pitches and rolls in response to wave action, a flow of liquid in a generally figure of eight configuration as indicated by arrows 110 can be induced, for driving the turbine as the liquid flows through the chamber 103. A reversible turbine as above described is utilised. The arrangement reduces internal stresses in the apparatus by controlling the flow of liquid therein so as to avoid the reversal of direction of flow at the ends of an elongate chamber.

Referring now to Figure 13 of the drawings, this shows an embodiment of the invention wherein flow of liquid within a chamber for power generation is caused to take place in a flow which does not undergo reversals of direction at opposite ends of the chamber. The apparatus comprises a generally rectangular structure 110 which is provided with inner and outer annular casing parts 111, 112 which together define an annular chamber 113. The rest of the structure 110 defines dry chambers 114 providing sufficient buoyancy to enable the apparatus to float. At diametrically opposed regions of the chamber 13 there are provided turbine chambers 115 in which are provided respective turbines drivable by flow of liquid therethrough, the turbines are connected by shafts 116 to respective generators 117. Between the chambers parts 115 in which the turbines are disposed there are respective flow-control gates 118 which are pivotable about respective pivots 119, in response to flow of liquid, between stops 120 and the casing part 111. The path of movement of the free ends of the gates 118, between the extreme positions shown in full lines in the drawing and in broken lines at 121, is as indicated at 122.

When the apparatus pitches and rolls in response to wave action, the effect of the gates 118 is to cause flow of the quantity of liquid contained in the chamber 113 in one direction around the chamber, as indicated by arrows 123. Flow through each of the turbines is thus unidirectional and the requirement for a turbine whose direction of rotation is reversible is eliminated.

Referring now to Figures 14 and 15 of the drawings, these show respectively in plan and elevation a configuration of float or buoyancy device which may be beneficial in apparatus according to the invention. It comprises a circular chamber 125 superimposed on a chamber 126 of narrower elongate configuration having opposite ends pointed. The shape of the latter chamber is such as to provide a decreased resistance when it is being towed from one of its ends, and thus when apparatus according to the invention is being moved by water to a desired location a float of this configuration is advantageously towed in a configuration such that the waterline lies on the lower chamber 126 and not the upper chamber 125. When at the desired position, it may be loaded to assume a position in which the water line lies on the upper chamber.

Referring now to Figures 16 and 17 of the drawings, these show an arrangement by which a generally circular structure such as illustrated in Figure 12, or a structure of the configuration of Figure 13, may be supported on a body of water so as to have its attitude changed by wave action. There is shown a generally triangular structure 130 having a respective float 131 at each corner. The floats are secured by respective fastenings 132, and each may include a ballast container as indicated at 133 to ensure stability when floating. Apparatus such as shown in Figure 12 or Figure 13, or as described hereafter, is supported on the structure 130 as indicated at 134. The apparatus may be moored by a cable 135 connected to the attachment point of one of the floats 131.

Figure 18 illustrates that apparatus according to the invention may be adapted to float below the surface of a body of water rather than on the surface. In Figure 18, an elongate chamber such, for example, as shown in Figures 1 and 2 of the drawings, is indicated at 140 and at each end it is connected by a respective supporting member 141 and cables 142, to floats 143 and ballast weights 144. Floats 143 float at the surface of the body of water as indicated at 145, whilst the ballast weights 144 ensure that the chamber 140 is suspended below the surface of the body of water in such a way as to be moved in respect of its attitude as the floats 143 move with wave action. Also visible in Figure 18 is a passage 146 providing for flow of air between opposite ends of the chamber in the opposite direction to that in which water flows between the ends of the chamber as the attitude of the chamber changes.

Referring finally now to Figures 19 to 21 of the drawings, these are respectively a front elevation, plan and side elevation of yet a further embodiment of apparatus according to the invention. This embodiment of apparatus is intended to float in a semi-submerged condition at the surface of a body of water: it comprises a structure 150 of circular shape in plan view which is intended to be provided with three floats of which one, shown at 151, is at a part of the circumference of the structure which will herein be termed the front thereof. The two further floats would be provided at the rear of the structure 150, spaced laterally thereof from one another. The float 151 is provided with a mooring point 152. Transversely of the structure 150 there extend two walls 153 which divide the structure into front and rear portions intended to contain liquid such as water for displacement as the apparatus changes its attitude: between the walls 153 there is a part 154 which is intended to remain dry for providing additional buoyancy to the apparatus.

Centrally of the apparatus and beneath the circular structure 150 there is disposed a turbine chamber 155 in which there is a turbine 156. The shaft of turbine 156, as shown at 157, extends to a generator 158 disposed within the float 151. Forwardly and rearwardly of the turbine chamber 155, beneath the circular structure 150, there extend respective passages 159 which widen with increasing distance from the turbine and have part-cylindrical lateral walls 160 which, as the passages 159 become wider and the walls 160 thereof diverge from one another, to afford V-shaped openings 161 providing access for liquid to the passages 159 from the front and rear portions of the chamber within the circular structure 150. Flow-directing elements 162 may be provided as indicated in Figure 21 at the ends of the passages 159.

In use, it is intended that apparatus as shown in Figures 19 to 21 should float on a body of water at a level such that the waterline under still water conditions is approximately as indicated 163 in Figure 19. When flow of water occurs within the passages 159 and communicating parts of the interior of the circular structure 150, the main mass of such flow occurs below water level inside the turbine chamber 155, for maximum turbine efficiency. Structural stresses on the overall structure of the apparatus are minimised.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or jn terms of a means for performing the disclosed function, or a method or process for attaining ^"the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. Apparatus comprising means defining a chamber adapted to be supported in such a way as to change its attitude in response to a natural influence thereon, and containing a liquid which is able to flow between different parts of the chamber in consequence of said attitude change; and power generating means drivable by said liquid in the course of its flowing between the different parts of the chamber.

2. Apparatus according to claim 1 wherein said chamber is adapted to float on a body of water, and said liquid flows between different parts of the chamber when the chamber changes its attitude as a result of being affected by waves on the surface of the water. .

3. Apparatus according to claim 2 wherein the chamber is of elongate configuration, having floatation means at its opposite ends and adapted to undergo a pitching motion under the influence of waves.

4. Apparatus according to any one of the preceding claims wherein the power generating means is a rotary device or devices, drivable by the flowing liquid and having a mechanical output which may be connected to an electrical generator or generators.

5. Apparatus according to claim 3, or claim 4 as appendant thereto, herein power generating means comprises at least one device disposed at a position between the ends of the chamber, preferably approximately mid-way therebetween.

6. Apparatus according to claim 5 wherein the power generating means comprises at least one axial flow turbine device, having blades disposed about a shaft extending generally lengthwise of the chamber.

7. Apparatus according to claim 5 or claim 6 wherein power generating means is provided at or adjacent one or both ends of the chamber, to be driven by the liquid in the course of reversal of its direction of flow which occurs at such ends of the chamber.

8. Apparatus according to any one of the preceding claims further comprising power generating means arranged to be driven by the flow of air in the chamber which occurs in the opposite direction to the flow of liquid therein.

9. Apparatus according to any one of the preceding claims wherein liquid in the chamber is water, so that the quantity of liquid in the chamber may be added to or reduced by providing appropriate communication with the body of water on which the apparatus is floating.

10. Apparatus according to claim 6 or any claim appendant thereto wherein the turbine comprises blades mounted relative to the shaft of the turbine in such a way as to be able to orientate themselves automatically in response to the flow of liquid, so that whichever direction the liquid is flowing, the shaft is caused to rotate in one direction only.

11. Apparatus according to claim 10 wherein the blades are also able to orientate themselves to assume an inclination or pitch dependent on the rate of flow of liquid past them.

12. Apparatus according to any one of the preceding claims wherein said chamber is arranged to float at the surface of a body of water.

13. Apparatus according to any one of claims 1 to 11 wherein said chamber is arranged to be suspended beneath the surface of a body of water.

14. Apparatus according to any claim appendant to claim 6 wherein said turbine device is disposed at a position lower than parts of said chamber spaced from the turbine device.

15. Apparatus according to claim 5 or any claim appendant thereto wherein said chamber is of increased cross-sectional area, compared with that at said power-generating device, at positions spaced from said power-generating device.

16. Apparatus according to claim 5 or any claim appendant thereto wherein said chamber is at least partly defined within a structure of generally circular configuration.

17. Apparatus according to claim 16 comprising at least one wall formation extending transversely of said generally circular structure to define chamber portions at opposed parts of said structure, and passage means connecting said chamber portions and containing said power generating device.

18. Apparatus according to claim 17 wherein said passage means is disposed beneath said generally circular structure.

19. Apparatus according to claim 2 or any claim appendant thereto comprising movable flow-directing members for directing flow of water in said chamber.

20. Apparatus according to claim 2 wherein said chamber is of annular configuration and includes means for causing flow of water in one rotational sense in the chamber.

21. Apparatus according to claim 20 comprising one or more power- generating devices disposed at a position in said chamber or at positions spaced circumferentially thereof.

22. Apparatus according to claim 21 wherein the or each device comprises an axial flow turbine device.

23. Apparatus substantially as hereinbefore described with reference to any one of the accompanying drawings.

24. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.