WO2020014729A1

WO2020014729A1 - Wave powered generator

Info

Publication number: WO2020014729A1
Application number: PCT/AU2019/000082
Authority: WO
Inventors: Eamon Bergin
Original assignee: Eamon Bergin
Priority date: 2018-07-16
Filing date: 2019-07-11
Publication date: 2020-01-23

Abstract

There is an apparatus for generating electrical power from water waves. The apparatus in a position of use includes a chamber (1) having an open lower end (2) for the entry and exit of water when submerged therein during pressure changes, a closed upper end (3) for retaining a pocket of compressible gas, a throat (4) of reduced cross-section connecting said upper and lower ends and an impeller (5) disposed in or adjacent said throat for converting a flow of water through said throat (4) into rotational energy for operating an electrical generator.

Description

W AVI I’OW I l IM.IM R L I < >l<

Tliis invention relates to power generation. More particularly, although not exclusively it discloses a wa e powered generator tor extracting electrical energy from wave mo ement in water.

BA ^'KCiKOl 'NI⁾ l(⁾ M il INVENTION

I he physics of wave act ion dictate that the motion of the water is essential!) oscillator) with the direction reversing ever) cvcle. With prior art wave powered generators an effectiv e conv ersion of this oscillating wav e action to shall rotation has not been possible without apparatus having numerous moving parts as described for example in l >S patent 424^l>084. Such prior art wave powered generators are therefore expensive to construct and maintain. I hex are also susceptible to damage in an ocean env ironment. The ocean is violent and as prior art wave powered generators typically require equipment located at or adjacent the water surface the) are easily damaged b\ winds and/or continuous!₎ breaking wave fronts.

SUMMARY OF fill IWTNTION

It is therefore an object of this inv ention to ameliorate the aforementioned

disadvantages and according!₎ an apparatus f r generating electrical power from water w av es is disclosed, said apparatus in a position of use including a chamber having an open lower end for the entrv and exit of water when submerged therein din ing pressure changes a closed upper end for retaining a pocket of compressible gas. a throat of reduced cross-section connecting said upper and lower ends and an impeller disposed in or adjacent said throat for conv erting a flow of water through said throat into rotational energv for operating an electrical generator.

Preferablv said chamber is bell shaped.

It is further pre erred that said chamber, in use of the generator, is anchored below the surface of a body of water by mooring fixtures having calibrated springs.

1

Substitute Sheet

(Rule 26) RO/AU BRIEF DESCRIPTION OF THE DRAWINGS

One preferred embodiment of the invention will now be described with reference to the attached drawings in which:-

Figure 1 is a schematic elevation view of a wave powered generator according to the invention.

Figure 1 A is a plan view of the wave powered generator of figure 1.

Figure IB is a cross-sectional view along the lines A-A of figure 1A.

Figure 1 C is a schematic cross-sectional view of the wave powered generator of figure 1 when submerged in a body of water with the crest of a wave passing directly over,

Figure 2 is a later view the wave powered generator of figure 1C as the downward sloping back portion of the wave subsequently passes over, and

Figure 3 is a still later view of the wave powered generator of figure 1C as the wave trough passes over.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to figure 1 the wave powered generator may comprise a bell-shaped chamber indicated generally as 1 with an enlarged open lower end 2, a closed bulbous upper end portion 3 and a connecting throat 4 of restricted cross-section. There is also an impeller indicated symbolically at 5 which is mounted in or adjacent the throat 4 to convert axial fluid flow through said throat into rotational energy. The chamber in use is preferably moored in a submerged position by means of rods 6 which extend down from adjacent the periphery of the open lower end 2 to

anchorages on a lakebed or seabed 6A below. The chamber preferably has rings 7 fixed to it which slide vertically along the rods 6 against the force of coil springs 8. This allows the chamber a restricted vertical movement for reasons described later. In figure 1C the chamber 1 is shown submerged in water 8A below the crest of a wave 9 passing over directly above. The chamber is filled with water up to a level indicated by broken line 10 in the upper closed portion 3 which traps a pocket 11 of air or other gas. At this point in the cycle of operation the gas pocket 11 is being compressed in accordance with absolute pressure applied from the depth A of water between the top of the wave crest and the bottom of the open chamber 2, acting on water level 10 in the pocket. As the crest 9 moves on and downward sloping back portion 12 of the wave subsequently passes over as shown in figure 2, the reduced depth B of water measured from the underside on the open vessel 2, results in a decreased absolute pressure on the gas pocket 11 whereby it expands in accordance with Boyle’s Law. This expansion continues as the lowest area of trough 13 preceding the next wave passes over as shown in figure 3 to further reduce the depth C of water above the chamber and pressure on the pocket 11. This expansion expels a

corresponding volume of water from the upper portion 3 of the chamber and down through the throat 4 (see arrow D) where it turns the impeller 5. The impeller 5 preferably preferably includes a built-in electrical generator. Alternatively the impeller could be connected by a mechanical drive linkage to any suitable form of remote electrical generator (not shown) external to the chamber in order to produce usable power. The design of a suitable electrical generation apparatus would be well within the capabilities of a person skilled in the art. See for example Power

Generation Handbook: Selection, Applications, Operation,

Maintenance McGraw-Hill Professional; 1 st edition (August 28, 2002) ISBN- 13 : 978-0071396042.

The aforementioned cycle then repeats with the upward slope of the next wave crest again increasing the depth of water over the chamber to compress the gas pocket whereby water is drawn back up the throat into the bulbous upper end 3. With this the impeller is again rotated to preserve continuous power generation. The buoyancy of the chamber 1 will fluctuate with the cyclic compression/expansion of the gas or air pocket as described above. In order to allow and enhance the corresponding vertical movement of the chamber along the rods 6 springs 8 are preferably fitted as referred to above. More specifically when the gas pocket 11 is compressed as shown in figure 1C it will sink on the rods 6 against the action of the springs 8. As the pocket subsequently expands as shown in figure 2 and 3 the chamber will rise on the rods 6. This, it is believed, enhances the output and efficiency of the power generation as it increases the cyclic variation of the absolute pressure applied to the gas pocket 1 1 as the waves pass over. This in turn increases the water flow through the throat.

When the above described wave powered generator with a 1 cubic meter gas pocket is anchored at a depth of 2 meters measured from the underside of vessel 2, to the surface of water each compression and expansion of the gas pocket will produce a water displacement of 63 litres each way which a total of 126 litres on a wave is passing over a just one meter.

It will thus be appreciated that this invention, at least in the form of the embodiment described, provides a novel and improved form of wave powered electrical generator. It operates with a reduced number of moving parts compared to prior art installations and, as it operates completely submerged, it is protected from damaging winds and breaking waves. The embodiment described however is only the currently preferred form of the invention and a wide variety of modifications may be made without departing from the scope thereof. For example the shape, configuration and dimensions of the chamber as well as the design of the impeller, drive linkage, electrical generator and anchoring fixtures may all be changed according to application requirements. Also, the invention is not limited to any particular material for constructing the chamber although stainless steel, fiberglass or other robust and saltwater resistant materials are preferred.

Claims

The claims

1. Apparatus for generating electrical power from water waves, said apparatus in a position of use including a chamber having an open lower end for the entry and exit of water when submerged therein during pressure changes, a closed upper end for retaining a pocket of compressible gas, a throat of reduced cross-section connecting said upper and lower ends and an impeller disposed in or adjacent said throat for converting a flow of water through said throat into rotational energy for operating an electrical generator.

2. The apparatus as claimed in claim 1 wherein said chamber is bell shaped.

3. The apparatus as claimed in claim 2 wherein rods are fitted to said chamber and in use said chamber is moored in a submerged position by means of said rods which extend down to anchorages on a seabed or lakebed.

4. The apparatus as claimed in claim 3 wherein said chamber has rings on the lower end which slide along said rods to allow vertical movement of said chamber relative to said rods.

5. The apparatus as claimed in claim 4 wherein said rings slide along the rods

against the force of calibrated coil springs fitted around said rods.