WO2018150387A1

WO2018150387A1 - A depending wave pump

Info

Publication number: WO2018150387A1
Application number: PCT/IB2018/051001
Authority: WO
Inventors: Mpumzi Siphesihle SWANA
Original assignee: Swana Mpumzi Siphesihle
Priority date: 2017-02-20
Filing date: 2018-02-19
Publication date: 2018-08-23
Also published as: ZA201904854B

Abstract

The invention relates to a wave energy conversion plant 10 for converting movement of ocean waves into electrical energy. The plant includes a wave energy conversion device 11, a reservoir 30 and an electrical generator 33. The device 11 includes at least one wave-absorbing vane 12, and a support structure 13 which includes a vane receiving formation 15 which is operatively raised from an ocean floor and to which the vane 12 is pivotally connected such that it depends from the formation 15 and extends toward the ocean floor. The vane pivots relative to the support structure 13 about a pivot axis X, in oscillating fashion, in response to wave motion incident upon the vane 12. The device 11 further includes four fluid pumps 22 connected to the vane 12 in order to translate pivotal displacement of the vane 12 into reciprocating pump action for pumping water.

Description

A DEPENDING WAVE PUMP

FIELD OF INVENTION

The invention relates generally to energy conversion. In particular, it relates to energy conversion from kinetic to electrical energy through use of an at least partially submerged energy conversion device which is powered by a renewable energy source in the form of ocean currents or waves.

BACKGROUND OF INVENTION

Different configurations of wave energy conversion devices have been developed, mostly for the purposes of converting renewable kinetic or wave energy into a desirable form of energy such as electrical energy. One such configuration makes use of a float positioned on the water surface which rises and falls with the ebb and flow of tides or incoming waves in order to displace an actuating arm or pump. A different configuration includes one or more hydro-turbines which are rotated when currents pass through the turbines. Another known configuration is in the form of a barrier which is positioned on the shoreline and pivotally displaced when waves impinge upon the barrier. Drawbacks associated with the above configurations relate to poor or insufficient energy conversion and the fact that the equipment or components are susceptible to damage due to the wave action, foreign objects or corrosion etc. US 7,023, 104 describes a wave energy conversion device for converting wave energy from wave motion in a body of water (the sea) to a pressurised fluid output which can be used for desalination purposes or for generation of electrical energy through use of hydro-turbines. This particular device comprises: a stable platform which is secured to a seabed; at least one fluid pump, a proximal end of which is pivotally connected to the platform; and a submerged wave-absorbing panel which is pivotally connected to the platform and operatively extends vertically upward from the platform, a distal end of the fluid pump being connected to the panel such that wave energy of waves moving through the sea are absorbed by the panel which exhibits an oscillating motion in response to the ebb and flow of waves. This oscillating motion is translated into reciprocating motion by the fluid pump which serves to pump sea water to a catchment area for further use. Although the above configuration may work in certain instances with favourable ocean conditions, the Applicant has noticed that the above configuration is ineffective in certain conditions where undesirable circling or spiralling undercurrents are present proximate the ocean floor. For example, with the passage of time, these undercurrents gradually deposit sand, sediment or other foreign objects on the platform and against a base of the panel which obstructs the oscillating motion of the panel and prevents full range of motion which renders the operation of the pump ineffective.

The present invention aims, at least to some extent, to alleviate the drawbacks discussed above.

SUMMARY OF INVENTION

In accordance with a first aspect of the invention, there is provided a wave energy conversion device which includes:

at least one wave-absorbing vane;

a support structure which includes a vane receiving formation which is operatively raised from an ocean floor and to which the wave-absorbing vane is pivotally connected in a configuration in which the wave-absorbing vane depends from the vane receiving formation and extends toward the ocean floor such that it is at least partially submerged in water and is configured to pivot relative to the support structure about a pivot axis, in oscillating fashion, in response to wave motion incident upon the wave-absorbing vane; and at least one fluid pump connected between the wave-absorbing vane and the vane receiving formation in order to translate pivotal displacement of the wave-absorbing vane into reciprocating pump action for pumping water. The wave energy conversion device may include at least two fluid pumps, one either side of the wave-absorbing vane. The wave energy conversion device may include a pair of fluid pumps connected to each major face of the vane. The fluid pumps within each pair may be disposed toward opposing sides of the wave-absorbing vane. Each fluid pump may be connected between the wave-absorbing vane and the vane receiving formation. The wave energy conversion device may be double-acting in the sense that each time the vane is displaced fluid is pumped by at least one of the fluid pumps.

The device may include a plurality of wave-absorbing vanes pivotally connected to the support structure. The vane receiving formation may include a pair of parallel, elongate beams or struts. The support structure may include a frame to which the beams are connected and a plurality of legs which are connected to the frame and extend downwardly therefrom to support the frame in a raised position.

The wave-absorbing vane may include louvres defining a plurality of openings passing through the vane.

The wave-absorbing vane may be rectangular and may include a peripheral border. The louvres may extend laterally between opposing sides of the border. The louvres may be inclined with respect to a plane of the border of the wave-absorbing vane.

The fluid pumps may include a check valve at an inlet and a check valve at an outlet for regulating flow of fluid into and from the pump.

Each fluid pump may include a cylinder and a piston. The cylinder may be pivotally secured to the vane receiving formation. The piston may be pivotally connected to the vane. The piston may be received within the cylinder in order to pump water.

Each fluid pump may include inlet and outlet one-way valves to facilitate pump action of the pump and suitable piping to convey pumped water to an elevated catchment area or reservoir.

The plane of the vane may pass through the pivot axis. Under influence of waves incident upon the vane, it may be configured to pivot back and forth about the pivot axis in a to and fro oscillating fashion.

The invention extends to a wave energy conversion plant which includes: at least one wave energy conversion device as described above wherein the wave-absorbing vane is at least partially submerged in water; a reservoir positioned at an elevated site, the fluid pump of the energy conversion device being in fluid flow communication with the reservoir such that water can be pumped to the reservoir by the fluid pump as a result of oscillating motion of the wave-absorbing vane induced by ocean waves, the reservoir being configured temporarily to store water; and

at least one hydro-turbine configured to generate electricity when the water stored in the reservoir is discharged therefrom over the hydro-turbine.

BRIEF DESCRIPTION OF DRAWINGS

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

In the drawings:

Figure 1 shows a three-dimensional view of a conceptual wave energy conversion plant which includes at least one wave energy conversion device in accordance with the invention;

Figure 2 shows a side view of the plant of Figure 1 with a wave- absorbing vane in a first position; and Figure 3 shows another side view of the plant of Figure 1 with the wave-absorbing vane in a second position;

Figure 4 shows a longitudinal section through a fluid pump of the device in an extended position; and

Figure 5 shows the fluid pump of Figure 4 in a compressed position.

DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT

The following description of the invention is provided as an enabling teaching of the invention. Those skilled in the relevant art will recognise that many changes can be made to the embodiments described, while still attaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be attained by selecting some of the features of the present invention without utilising other features. Accordingly, those skilled in the art will recognise that modifications and adaptations to the present invention are possible and can even be desirable in certain circumstances, and are a part of the present invention. Thus, the following description is provided as illustrative of the principles of the present invention and not a limitation thereof.

In the Figures, reference numeral 10 refers generally to a wave energy conversion plant which is configured to generate electrical energy from ocean waves. There has been an ever-increasing move toward generating electricity using renewable energy resources. One such renewable source of energy comes in the form of kinetic energy stored in ocean waves. The wave energy conversion plant 10 includes a wave energy conversion device 1 1 in accordance with the invention. In the example embodiment illustrated in the Figures, the device 1 1 includes a single wave-absorbing vane 12 which is operatively at least partially submerged in water so that waves incident upon the vane 12 displace it back and forth, in oscillating fashion, as will be elaborated on here below.

The wave energy conversion device 1 1 further includes a support structure 13 which includes a vane receiving formation 15 to which the wave-absorbing vane 12 is pivotally connected or mounted. The vane 12 operatively depends from the vane receiving formation 15 so that it can pivot relative to the vane receiving formation 15, and hence relative to the support structure 13 about a pivot axis X. The support structure 13 further includes a rectangular frame 16 and a plurality of legs 17 which support the frame 16 and vane receiving formation 15 in a raised or elevated position above an ocean floor. To this end, the legs 17 extend downwardly toward the ocean floor from four corners of the frame 16. The vane receiving formation 15 includes a pair of parallel, elongate beams or struts 18 which extend lengthwise between opposite ends of the frame 16.

The wave-absorbing vane 12 is substantially planar having opposing major faces and includes a rectangular peripheral border or casing 14 and a plurality of inclined louvres 20 which extend laterally between opposite sides of the border 14. The louvres 20 define openings or passages through the vane 12. A pair of two fluid pumps 22, each of which extends between the vane 12 and the vane receiving formation 15 at an inclined angle thereto, is connected to each face of the planar vane 12, on opposite sides of the border 14. Accordingly, the device 1 1 includes four fluid pumps 22 which are configured to pump water from the ocean to a reservoir 30 via suitable piping. Pump action of the fluid pumps 22 is induced by the oscillating back and forth motion of the vane 12 due to waves incident upon the major faces of the vane 12 (see Figures 2 and 3). Referring now to Figures 4 and 5, each fluid pump 22 comprises a hollow, circular cylindrical pump cylinder 23 which is pivotally connected to the strut 18 of the vane receiving formation 15 by way of a clevis fastener and a reciprocating piston 24 which is disposed within the cylinder 23 and protrudes therefrom. A free end of the piston 24 is pivotally connected to the border 14 of the vane 12 by way of a clevis joint 26. The piston 24 is configured to reciprocate within the cylinder 23 in order to pump water therefrom as the vane 12 moves to and fro. Each cylinder 23 has an inlet check valve or oneway valve 27 at an inlet through which water can be drawn into a pump chamber 25 defined by the cylinder 23 and an outlet check valve or one-way valve 28 at an outlet through which water can be pumped from the pump chamber 25 under influence of the piston 24. The valves 27, 28 control unidirectional flow of water through the cylinder 23 and chamber 25. Each piston 24 has a head 29 disposed within the cylinder 23 which sealingly abuts an inner wall of the cylinder 23.

The wave energy conversion plant 10 includes the reservoir 30 which is mounted on top of the support structure 13 and is configured temporarily to hold water pumped from the fluid pumps 22. A suction pipe 31 is connected to the inlet check valve 27 of each pump 22 and operatively hangs in the water to suck water into the pump chamber 25. A discharge hose 32 is connected between the outlet check valve 28 and the reservoir 30 in order to convey water pumped from the pump chamber 25 to the reservoir 30. The plant 10 further includes an electrical generator in the form of a water turbine 33 which generates electricity when water is discharged from the reservoir over the turbine via a discharge outlet 34.

A wave incident on the major face of the vane 12 will cause the vane 12 shown in Figure 2 to pivot to the right toward the position illustrated in Figure 3. This movement displaces the pump 22 from its compressed position illustrated in Figure 5 to its extended position shown in Figure 4 which means the piston head 29 is axially outwardly displaced which draws water into the pump chamber 25 via the inlet check valve 27 as shown in Figure 4. As the wave current reverses and impinges upon the opposite major face of the vane 12, it pivots in the opposite direction (right to left in Figure 3) which causes the water retained in the chamber 25 of the left-hand side pump 22 to be pumped from the chamber 25 to the reservoir 30 via the outlet check valve 28 as the piston head 29 moves axially inward relative to the cylinder 23, as can be seen in Figure 5.

The device 1 1 is therefore double-acting in the sense that with each swaying motion of the vane 12, water is pumped from at least one pair of fluid pumps 22. It is to be appreciated that the vane 12 may be displaced from one side to the other up to 4 times per minute due to the ebb and flow of ocean waves or currents. Once a sufficient volume of water has accumulated within the reservoir 30, it can be discharged therefrom and released over the water turbine 33 to generate electricity in conventional fashion. The device 1 1 can also be used for desalination purposes.

A major advantage of the wave energy conversion plant 10 and device 1 1 in accordance with the invention over known prior art configurations is the fact that the wave-absorbing vane 12 is elevated or raised above, and spaced away from, the ocean floor which means sand and sediment cannot be deposited against the vane 12 and impede or prevent it from oscillating back and forth. This benefit is achieved by having the vane 12 depend downwardly from the support structure 13 instead of the vane protruding vertically upward from the ocean floor or from a platform built on the ocean floor. Deposited sand, sediment or other foreign bodies can therefore not impede movement of the vane 12. Wave currents are also more directional and hence directly incident upon the major faces of the vane 12 at a level spaced from the ocean floor. In this manner, spiralling or circling undercurrents, which typically occur on the ocean floor, which do not result in positive displacement of the vane 12, but in fact hinder its displacement and may cause damage to the components of the device 1 1 , are avoided. It is desirable for the entire vane 12 to be submerged in water during use. Due to the fact that the vane 12 is elevated from the ocean floor, these undesirable spiralling undercurrents at the ocean floor have a very limited effect on the oscillating movement of the vane 12 above.

Claims

CLAIMS:

1. A wave energy conversion device which includes:

at least one wave-absorbing vane;

a support structure which includes a vane receiving formation which is operatively raised from an ocean floor and to which the wave-absorbing vane is pivotally connected in a configuration in which the wave-absorbing vane depends from the vane receiving formation and extends toward the ocean floor such that it is at least partially submerged in water and is configured to pivot relative to the support structure about a pivot axis, in oscillating fashion, in response to wave motion incident upon the wave-absorbing vane; and

at least one fluid pump connected between the wave-absorbing vane and the vane receiving formation in order to translate pivotal displacement of the wave-absorbing vane into reciprocating pump action for pumping water.

2. A wave energy conversion device as claimed in claim 1 , which includes at least two fluid pumps, one either side of the wave-absorbing vane.

3. A wave energy conversion device as claimed in claim 2, which includes a pair of fluid pumps connected to each major face of the vane, the fluid pumps within each pair being disposed toward opposing sides of the wave- absorbing vane, each fluid pump being connected between the wave- absorbing vane and the vane receiving formation.

4. A wave energy conversion device as claimed in any one of the preceding claims, which includes a plurality of wave-absorbing vanes pivotally connected to the support structure.

5. A wave energy conversion device as claimed in any one of the preceding claims, wherein the vane receiving formation includes a pair of parallel, elongate beams, the support structure including a frame to which the beams are connected and a plurality of legs which are connected to the frame and extend downwardly therefrom to support the frame in a raised position.

6. A wave energy conversion device as claimed in any one of the preceding claims, wherein the wave-absorbing vane includes louvres defining a plurality of openings passing through the vane.

7. A wave energy conversion device as claimed in claim 6, wherein the wave-absorbing vane is rectangular includes a peripheral border, the louvres extending laterally between opposing sides of the border.

8. A wave energy conversion device as claimed in claim 7, wherein the louvres are inclined with respect to a plane of the border of the wave- absorbing vane.

9. A wave energy conversion device as claimed in any one of the preceding claims, wherein the fluid pumps include a check valve at an inlet and a check valve at an outlet for regulating flow of fluid into and from the pump.

10. A wave energy conversion device as claimed in any one of the preceding claims, wherein each fluid pump includes a cylinder and a piston, the cylinder being pivotally secured to the vane receiving formation, the piston being pivotally connected to the vane and being received within the cylinder in order to pump water.

1 1 . A wave energy conversion device as claimed in claim 10, wherein each fluid pump includes inlet and outlet one-way valves to facilitate pump action of the pump and suitable piping to convey pumped water to an elevated catchment area or reservoir.

12. A wave energy conversion device as claimed in claim 8, wherein the plane of the border passes through the pivot axis.

13. A wave energy conversion device as claimed in any one of the preceding claims, wherein, under influence of waves incident upon the vane, it is configured to pivot back and forth about the pivot axis in a to and fro oscillating fashion.

14. A wave energy conversion plant which includes:

at least one wave energy conversion device as claimed in any one of the preceding claims wherein the wave-absorbing vane is at least partially submerged in water;

a reservoir positioned at an elevated site, the fluid pump of the energy conversion device being in fluid flow communication with the reservoir such that water can be pumped to the reservoir by the fluid pump as a result of oscillating motion of the wave-absorbing vane induced by ocean waves, the reservoir being configured temporarily to store water; and