GB2467611A

GB2467611A - Wave energy apparatus with platform height control system

Info

Publication number: GB2467611A
Application number: GB0906864A
Authority: GB
Inventors: Alvin Smith
Original assignee: Dartmouth Wave Energy Ltd
Current assignee: Dartmouth Wave Energy Ltd
Priority date: 2009-02-07
Filing date: 2009-04-22
Publication date: 2010-08-11
Also published as: GB0906864D0; GB0902076D0

Abstract

Wave energy apparatus having a submerged piston column platform 22 in a body of water, the platform being of variable height, a buoyant wave energy receiver 2 moves reciprocally with respect to the platform and a platform height control system varies the height of the platform so the height is lowered as the level of water recedes to maintain the wave energy receiver at the surface of the water. A pump 9 is operated by reciprocal motion of the surface float 2 with respect to the platform. The height control system has activation means acting between the platform and the float. Fluid being let in or out of the platform column chamber 24 increases or decreases the height of the platform. Fluid may be pumped into the chamber from the pump through a restricted aperture 36 and non return valve 37 to extend the platform until a knock down limit valve 35 strikes the striker plate 38 allowing fluid to flow out of the chamber to lower the platform. An additional float 32 may be provided to raise the platform.

Description

Renewable energy method of extending and retracting a platform.

Advantage The advantage over an earlier design is that the earlier design extends a pumps connecting rod upwards to it's maximum travel before it lifts the extendable column by pulling against a stop buffer 11, figure lB.

In this later design the crucial difference is that a connecting piston rod has the additional support of the raised piston column 22 which protects the con rod from lateral bending forces.

In this later design an additional external float or floats 32 attached to the rising piston column can raise the column piston platform using adequate buoyancy, even if the mobile column piston 22 incorporates a flooded configuration 33 figure 313 & 4W If hydraulic pressure is used to raise the mobile column 22, the hydraulic pressure required can be produced by different forms of renewable energy.

It can be in the form of floats 2 and weights 3 connected to pistons 12, lB the pistons can be lubricated by water so that no oils are required, it can use water as the hydraulic fluid so no hydraulic oils are required.

It can use buoyancy 2 in the form of displacement as a renewable energy form and it can use gravity in the form of weight 3 on a float as a renewable energy form to pressurise a fluid in a cylinder 9 to force a piston 12 to hydraulically extend a rising piston column platform 22 including its attached components and weights, and also provide sufficient mechanical ability to oppose and overcome any dynamic vertical forces created from an attached wave or swell or gravity energised converter.

Examples of the invention will now be described by referring to the accompanying drawings.

Figure lB shows item 32, the floatation to provide additional buoyancy to assist raising column 22.

Figures 2B & 6B shows item 34, fluid feed pipe to flooded column chamber 24, limit valve 35. & bleed pipe 45.

Figure 3B, 4B & SB show open base of piston platform column 22 with flooded chamber 33.

Figures 4B, 5B, 7B & 8B shows restricted aperture 36 from high pressure cylinder 9 to non return valve 37.

Figure SB shows detail of knockdown limit valve 35, restricted pressurised column fluid inlet 36 & non return valve 37 to open flooded piston column chamber 33.

Figure 6B shows detail base of flooded chamber column 24, base of column piston platform 22, two way fluid feed pipe 34, inlet outlet termination 43 and fluid bleed pipe 45.

Figure 78 shows detail of one way link pipe 41 to outlet pipe 34 & detail of two way lower pipe 44 terminating at 43 through air captive column piston platform base 22.

Swnmary of the invention According to the invention there is provided a wave energy apparatus comprising: a platform to be submerged in a body of water in use, the platform being of variable height with respect to the bed of the body of water; a buoyant wave energy receiver arranged to move reciprocally with respect to the platform as waves traverse the surface of the body of water; and a platform height control system for varying the height of the platform with respect to the bed of the body of water, the platform height control system comprising activation means acting between the platform and the wave energy receiver; wherein the activation means is configured to activate the platform height control system to lower the height of the platform as the depth of the body of water recedes, such that the wave energy receiver is maintained substantially at the surface of the body of water.

The platform height control system may be configured to lower the platform in response to a minimum threshold separation being reached between the wave energy receiver and the platform.

The platform height control system may be configured to raise the height of the platform in the body of water until the minimum threshold separation between the platform and the wave energy receiver is reached.

The wave energy apparatus may comprise a pump acting between the platform and the wave energy receiver, the pump being operated by the reciprocal motion of the wave energy receiver with respect to the platform. The pump may be double-acting.

The pump may be supported by the platform beneath the surface of the body of water.

The activation means may comprise a primary part associated with the wave energy receiver and a secondary part associated with the platform. The activation means may be configured to activate the platform height control system to lower the height of the platform on contact between the primary and secondary parts when the minimum threshold separation between the wave energy receiver and the platform is reached.

The platform height control system may comprise an extension portion that extends from the platform towards the wave energy receiver in use. The extension portion may move vertically in the water together with the platform. The extension portion may have an upper end closest to the wave energy receiver, and the secondary part of the activation means may be located at said upper end. The threshold separation between the platform and the wave energy receiver may be determined by the vertical displacement of the extension portion above the platform in use.

The platform may have first and second parts. The first part may be secured to the bed of the body of water. The second part may be moveable relative to the first part to vary the height of the platform in the body of water.

A chamber may be defined between the first and second parts of the platform. The wave energy apparatus may comprises an inlet for allowing fluid into the chamber as the height of the platform increases in the body of water. The wave energy apparatus may comprise an outlet for allowing fluid out of the chamber to decrease the height of the platform in the body of water. The outlet may be defined by a conduit extending from the chamber. The conduit may be defined by the extension portion and the outlet is at the upper end of the extension portion. The inlet may be provided on the conduit. The inlet may define a restricted flow path for restricting the flow of fluid into the chamber.

The wave energy apparatus may comprise an outlet valve for selectively controlling fluid flow out of the chamber through the outlet. The activation means may be configured to activate the outlet valve to allow fluid to flow out of the chamber when the minimum threshold separation between the wave energy receiver and the platform is reached.

The wave energy apparatus may be adapted to allow fluid to enter the chamber rapidly in the event of a sudden increase in wave height and/or depth thereby enabling the height of the platform to increase rapidly in response. A further inlet may be provided in fluid communication with the chamber. The further inlet may define a substantially unrestricted flow path for fluid into the chamber. p.

The wave energy apparatus may comprise a pressure-activated inlet valve for controlling fluid flow through said further inlet. The pressure-activated inlet valve may be arranged to allow fluid to flow through said further inlet and into the chamber when the pressure in the chamber falls below a predetermined pressure level. The outlet valve and the pressure-activated inlet valve may utilise a common valve member.

A high-pressure flow path may be defined between the pump and the chamber. The pump may be configured to pump fluid into the chamber via the high pressure flow path. The high-pressure flow path may be configured to restrict the rate of fluid flow from the pump to the chamber.

The second part of the platform may be flooded such that the chamber extends within the second part. Alternativly, the second part of the platform may be air or gas captive. The first and second parts of the platform may be hydraulically coupled.

The second part of the platform may be in the form of a column. The first part of the platform may be supported in the body of water by a first float. The second part of the platform may include a second float. The first part of the platform may be secured to the bed of the body of water by a tether. Alternatively, the first part may be secured to the bed via a fulcrum or pivot or piled into the bed. The wave energy receiver may comprise a surface float assembly arranged to float at the surface of the body of water, above the plafform. The surface float assembly may comprise a float and a weight.

The inventive concept includes a wave energy apparatus for location in a body of water, the wave energy apparatus comprising: a platform to be submerged in the body of water, the platform having first and second parts; the first part being secured to the bed of the body of water, and the second part being moveable relative to the first part to vary the height of the platform in the body of water; a surface float assembly arranged to float at the surface of the body of water above the platform in such a way that surface waves cause the surface float assembly to move reciprocally relative to the platform; a pump acting between the platform and the surface float assembly, the pump being operated by the reciprocal motion of the surface float assembly with respect to the platform; a chamber defined between the first and second parts of the platform; the chamber communicating with an inlet for allowing fluid into the chamber as the second part of the platform moves relative to the first part so as to increase the height of the platform in the body of water; the chamber further communicating with an outlet for allowing fluid out of the chamber as the second part of the platform moves relative to the first part so as to decrease the height of the platform in the body of water; and a platform height control system for moving the second part of the platform relative to the first part, the platform height control system comprising activation means acting between the platform and the surface float assembly; wherein the activation means is configured to activate the platform height control system to allow fluid out of the chamber through the outlet so as to decrease the height of the platform in the body of water as the depth of the body of water recedes, such that the surface float assembly is maintained substantially at the surface of the body of water.

Description

The Invention is a method of utilising renewable energy to energise hydraulic pistons, and hydraulic valves to extend or retract an immersed column platform.

The platform hydraulics are pressurised by gravity and wave or swell powered energy converters. I refer to my previously granted UK patent Hydro Column no GB 2445951 for reference purposes to show difference of invention.

In my new invention the invention uses additional buoyancy in the form of an additional float or floats 32 attached to a rising piston column platform, to raise or assist to raise that piston column platform, the rate of ascent being controlled by the amount of fluid being drawn in through a restricted aperture by the large area piston and the large volume of fluid required to allow great movement of the piston 22 in the flooded column 23 when working in relation with the smaller area high pressure piston in the high pressure cylinder 9 or other pressure cylinder wave converters. The afore said system controlling the piston column platform allowing it to creep upwards slowly with the said buoyancy of the additional float or floats 32 and or a rising tide until it's striker plate 38 strikes a knock down hydraulic travel limit valve 35. When this limit valve 35 opens it allows a great amount of fluid to escape quickly from the flooded column chamber 24, which then allows the piston platform 22 to retract quickly, being forced down by another surface weighted float 2, or other weight in the passing wave 01, or swells trough, until the valve 35 striker plunger clears the striker plate 38 at which point the limit valve 35 closes and prevents any further fluid passing out and hydraulically stabilises the column piston 22 platforms vertical movement, upon which the piston column platform 22 then repeats the afore said slowly rising creep situation but resisting forces created by incorporated wave energy converters.

Alternatively or as well as, my new invention uses some volume of fluid supplied through a restricted aperture 36 or not through a restricted aperture, but through a non return valve 37 from a higher pressure cylinder 9, to transfer additional fluid through into the flooded chamber 24& 33 column, which although the transferred fluid is under a lower pressure than the fluid in the higher pressure cylinder 9, it hydraulically extends a column piston 22 which said piston 22 is of a greater surface area than the higher pressure cylinder 9 piston, and raises the column piston platform 22 until it strikes the afore said knock down hydraulic travel limit valve 35which regulates the height or travel limit of the piston column platform 22.

Alternatively or as well as, the new invention can allow a fluid to enter through the base of the open based column 33 of a rising piston column platform 22 thereby flooding the piston column 33 as well as the flooded outer column chamber 24. The extra displacement of the additional float 32 on the piston column platform 22 replaces the air filled column buoyancy and the additional float or floats 32 will be of sufficient displacement to lift the weight of the piston column platform 22 and all components on the rising part of the piston column platform 22 only, but not the wave float 2 and weight 3 on the wave float which will be of sufficient weight to push the column 22 back down in a wave or swells trough when the afore said knock down limit valve 35 is opened by being struck by the surface float 2 or weight 3 on the surface float.

Description contd

Alternatively or as well as, pressurised fluid from a high pressure cylinder 9, and although at a lower pressure as it enters the flooded columns chambers 24 & 33 can extend the now flooded piston column platform 22 until it strikes the afore said knock down hydraulic travel limit valve 35 which allows the fluid to escape thereby limiting the height or travel of the piston column platform 22.

Alternatively or as well as, the piston column platform 22 can draw a fluid in through the knock down preset sprung loaded hydraulic travel limit valve 35, or through a restricted open fluid bleed inlet 45 into the flooded chamber 24 & 33, this allows the piston column platform 22 to extend slowly, due to a greater displacement of weight by the attached additional float -or floats 32 than that of the total weight of the mobile piston column platform 22 whether air filled 22 or flooded 33, excluding the surface float 2 and surface float weight 3.

The afore said systems can be used individually or used in any combination, to achieve the extending, raising, locking, creeping, or lowering of the piston column platform 22.

Description contd

The utilisation of renewable energy to extend or retract hydraulic pistons in a simple form is shown in figure lB.

The float 32, assists and ensures the air captive piston platform 22 will rise, due to sufficient buoyancy displacement of float 32, whereby a fluid which can be the surrounding water, is drawn in through a restricted but non valved inlet and outlet 45, to supply flooded chamber column 23, which allows column 22 to rise and fall in a regulated manner.

The column pistons rate of rise is dependant on the rate of in flow of fluid through the restricted Inlet outlet 45 created by the displacement buoyancy of the attached sub water float 32 and the opposing vertical forces applied to the columns piston 22 and subsequent depression variation applied to the hydraulic fluid within the flooded columns cylinder chamber 24.

The columns piston rate of fall is dependant on the rate of out flow of fluid through the restricted inlet outlet 45 created by the weight of a weighted surface float or other wave converters weight in the trough following a wave or swell and the vertical forces applied to the columns piston 22 and subsequent pressure variation applied to the hydraulic fluid within the flooded columns cylinder 24.

The utilisation of renewable energy to extend or retract hydraulic pistons in a different form is now shown and described as in figure 2B.

The pipe 34 figure 2B & 6B allows a fluid which can be the surrounding water to enter in through the restricted inlet 45, which allows column 22 to rise because air filled column 22 and the attached sub water float 32 will hold sufficient buoyancy displacement to raise the piston column platform 22 pius weight attached to the platform.

The restricted fluid inlet 45 will allow the piston column platform 22 to slowly rise until the knock down limit valve 35 strikes the strike plate 38 figure 6B attached to the underside of the surface float weight 3, or the knockdown limit valve 35 is struck by the descending surface float weight 3, in the following trough of a wave or swell, whereby the fluid is rapidly released and the weight of the surface float 2 and weight 3, or other surface floating attached wave converter will cause the column piston platform 22 to retract immediately to a height where the Knockdown limit valve 35 breaks contact from the strike plate 38 and the column 22 repeats its slow restricted ascent utilising the afore said renewable energy buoyancy displacement 32.

In figure 6B pipe 34 shows two way flow of fluid, this allows a large volume of water to be drawn in quickly to flooded chamber column 24, and or flooded column 33 figure 3B and 4B, when exceptional sudden wave heights require the column piston platform 22 figure 2B or column piston 33 figure 3 to be raised quickly at a speed, because the restricted inlet 45 can not supply sufficient volume of fluid to meet the demand from chamber 24 caused by sudden exceptionally high waves.

Description contd

In figure 4B and 5B, another method is shown utilising renewable energy driven pumps to provide pressure to a hydraulic fluid which can be water, to pressurise a piston column platform cylinder 22, by means of using pressurised fluid from the high pressure cylinder 9 of a wave or swell or gravity energised pump, passing liquid through a restricted aperture in a cylinder 36 and non return valve 37 in to the flooded column chamber 24 and flooded column piston chamber 33.

The pressurised fluid will force the column piston platform 22to extend until the knock down limit valve 35 strikes the striker plate 38, or when the surfce float 2 and weight 3 descend and the striker plate 38 when in a trough following a wave or swell, strikes the knock down limit valve 35 allowing a large volume of fluid to pass out from the flooded chambers 24 and 33 through the knock down limit valve 35.

This allows the column piston platform 22 to rapidly descend until the knock down limit valve 35 and strike plate 38 break contact, at which point the pressure from the high pressure cylinder pressurises the fluid in the flooded column chambers 24 and 33 and hydraulically resumes the raising operation.

In Figure 4B, 5B, 6B, 7B & 8B, fluid when demanded, can pass through pipe 34 in the opposite direction when drawn in past the preset sprung loaded knockdown limit valve 35, because of excessive or sudden wave or swell height.

The afore said excessive or sudden wave or swell height creates additional extending forces to the piston column 22, which in turn creates a greater depression in the flooded chambers 33 and 24, which is sufficient to hydraulically open the preset sprung loaded knock down limit valve 35, which allows fluid to flow in large quantity through pipe 34 in to the flooded chambers 24 and 33, which in turn allows the piston column platform 22 to ascend more rapidly than when pressurised from the high pressure cylinder 9 through the restricted aperture 36 and non return valve 37.

As the wave or swell passes, the following trough allows the piston column 22 chambers 24 and 33 to return to an extending to knock down limit valve situation.

Figure 7 B shows additional link pipe 41 which allows pressurised fluid to be pumped to the flooded column chamber 24 whilst column 22 can remain air captive, in this case additional float or floats 32 may not be required as the hydraulic pressure and air filled captive column 22 buoyancy may be sufficient to raise the piston column platform to the correct working position.

Figure 8B shows an extending piston column platform 22 and flooded chamber column 23 piled in to the water bed 31 this extending column piston platform 22 shown in figure 8B can utilise any of the preceding said operable methods singularly or in any operable combination

of the preceding specifications

Including the method or methods applying to figure 7B where float 32 may or may not be required as the weight of the column piston platform 22 will be lighter due to the column piston 22 being an air filled sealed chamber.

Claims

Claims 1. A wave energy apparatus comprising: a platform to be submerged in a body of water in use, the platform being of variable height with respect to the bed of the body of water; a buoyant wave energy receiver arranged to move reciprocally with respect to the platform as waves traverse the surface of the body of water; and a platform height control system for varying the height of the plafform with respect to the bed of the body of water, the platform height control system comprising activation means acting between the platform and the wave energy receiver; wherein the activation means is configured to activate the platform height control system to lower the height of the platform as the depth of the body of water recedes, such that the wave energy receiver is maintained substantially at the surface of the body of water.
2. The wave energy apparatus of Claim 1, wherein the platform height control system is configured to lower the platform in response to a minimum threshold separation being reached between the wave energy receiver and the platform.
3. The wave energy apparatus of Claim 1 or Claim 2, wherein the platform height control system is configured to raise the height of the platform in the body of water until the minimum threshold separation between the platform and the wave energy receiver is reached.
4. The wave energy apparatus of any preceding claim, further comprising a pump acting between the platform and the wave energy receiver, the pump being operated by the reciprocal motion of the wave energy receiver with respect to the platform.
5. The wave energy apparatus of Claim 4, wherein the pump is double-acting.
6. The wave energy apparatus of Claim 4 or ClaimS, wherein the pump is supported by the platform beneath the surface of the body of water.
7. The wave energy apparatus of any preceding claim, wherein the activation means comprises a primary part associated with the wave energy receiver and a secondary part associated with the platform, the activation means being configured to activate the platform height conirol system to lower the height of the platform on contact between the primary and secondary parts when the minimum threshold separation between the wave energy receiver and the platform is reached.
8. The wave energy apparatus of Claim 7, wherein the platform height control system comprises an extension portion that extends from the platform towards the wave energy receiver in use, the extension portion moving vertically in the water together with the platform, the extension portion having an upper end closest to the wave energy receiver, and the secondary part of the activation means being located at said upper end, wherein the threshold separation between the platform and the wave energy receiver is determined by the vertical displacement of the extension portion above the platform in use.
9. The wave energy apparatus of any preceding claim, wherein the platform has first and second parts: the first part being secured to the bed of the body of water, and the second part being moveable relative to the first part to vary the height of the platform in the body of water.
10. The wave energy apparatus of Claim 9, wherein a chamber is defined between the first and second parts of the platform, and the wave energy apparatus further comprises an inlet for allowing fluid into the chamber as the height of the platform increases in the body of water.
11. The wave energy apparatus of Claim 10, further comprising an outlet for allowing fluid out of the chamber to decrease the height of the platform in the body of water.
12. The wave energy apparatus of Claim II, wherein the outlet is defined by a conduit extending from the chamber.
13. The wave energy apparatus of Claim 12 when dependent upon Claim 8, wherein the conduit is defined by the extension portion and the outlet is at the upper end of the extension portion.
14. The wave energy apparatus of Claim 12 or Claim 13, wherein the inlet is provided on the conduit.
15. The wave energy apparatus of Claim 14, wherein the inlet defines a restricted flow path for restricting the flow of fluid into the chamber.
16. The wave energy apparatus of any of Claims 11 to 15, further comprising an outlet valve for selectively controlling fluid flow out of the chamber through the outlet, wherein the activation means is configured to activate the outlet valve to allow fluid to flow out of the chamber when the minimum threshold separation between the wave energy receiver and the platform is reached.
17. The wave energy apparatus of Claim 16, wherein the wave energy apparatus is adapted to allow fluid to enter the chamber rapidly in the event of a sudden increase in wave height and/or depth thereby enabling the height of the platform to increase rapidly in response.
18. The wave energy apparatus of Claim 17, comprising a further inlet in fluid communication with the chamber, the further inlet defining a substantially unrestricted flow path for fluid into the chamber.
19. The wave energy apparatus of Claim 18, wherein the wave energy apparatus further comprises a pressure-activated inlet valve for controlling fluid flow through said further inlet, the pressure-activated inlet valve being arranged to allow fluid to flow through said further inlet and into the chamber when the pressure in the chamber falls below a predetermined pressure level.
20. The wave energy apparatus of Claim 19, wherein the outlet valve and the pressure-activated inlet valve utilise a common valve member.
21. The wave energy apparatus of any of Claims 10 to 20 when dependent upon any of Claims 4 to 6, wherein a high-pressure flow path is defined between the pump and the chamber, and the pump is configured to pump fluid into the chamber via the high pressure flow path.
22. The wave energy apparatus of Claim 21, wherein the high-pressure flow path is configured to restrict the rate of fluid flow from the pump to the chamber.
23. The wave energy apparatus of any of Claims 9 to 22, wherein the second part of the plafform is flooded such that the chamber extends within the second part.
24. The wave energy apparatus of any of Claims 9 to 22, wherein the second part of the platform is air or gas captive.
25. The wave energy apparatus of any of Claims 9 to 24, wherein the first and second parts of the platform are hydraulically coupled.
26. The wave energy apparatus of any of Claims 9 to 25, wherein the second part of the platform is in the form of a column.
27. The wave energy apparatus of any of Claims 9 to 26, wherein the first part of the platform is supported in the body of water by a first float.
28. The wave energy apparatus of any of Claims 9 to 27, wherein the second part of the platform includes a second float.
29. The wave energy apparatus of any of Claims 9 to 28, wherein the first part of the platform is secured to the bed of the body of water by a tether, or via a fulcrum or pivot, or alternatively is piled into the bed.
30. The wave energy apparatus of any preceding claim, wherein the wave energy receiver comprises a surface float assembly arranged to float at the surface of the body of water, above the platform.
31. The wave energy apparatus of Claim 30, wherein the surface float assembly comprises a float and a weight.
32. A wave energy apparatus for location in a body of water, the wave energy apparatus comprising: a platform to be submerged in the body of water, the platform having first and second parts; the first part being secured to the bed of the body of water, and the second part being moveable relative to the first part to vary the height of the platform in the body of water; a surface float assembly arranged to float at the surface of the body of water above the platform in such a way that surface waves cause the surface float assembly to move reciprocally relative to the platform; a pump acting between the platform and the surface float assembly, the pump being operated by the reciprocal motion of the surface float assembly with respect to the platform; a chamber defined between the first and second parts of the platform; the chamber communicating with an inlet for allowing fluid into the chamber as the second part of the platform moves relative to the first part so as to increase the height of the platform in the body of water; the chamber further communicating with an outlet for allowing fluid out of the chamber as the second part of the platform moves relative to the first part so as to decrease the height of the plafform in the body of water; and a platform height coniroi system ior movmg me second part of the platform relative to the first part, the platform height control system comprising activation means acting between the platform and the surface float assembly; wherein the activation means is configured to activate the platform height control system to allow fluid out of the chamber through the outlet so as to decrease the height of the plafform in the body of water as the depth of the body of water recedes, such that the surface float assembly is maintained substantially at the surface of the body of water.
33. A wave energy apparatus substantially as herein described with reference to or as shown in any of Figures 2B to 8B of the accompanying drawings.