GB1571381A

GB1571381A - Generation of energy from marine sources

Info

Publication number: GB1571381A
Application number: GB45055/75A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-01-31
Filing date: 1977-01-31
Publication date: 1980-07-16

Description

(54) IMPROVEMENTS IN AND RELATING TO THE GENERATION OF ENERGY FROM MARINE SOURCES (71) I, ALBERT EDWARD DAVIES, a British Subject of "Hillspur", Park Copse, Dorking RHS 4BL, Surrey, do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to the generation of energy from marine sources.

There are numerous proposals for extracting energy from the sea. I provide apparatus in which a flexible member moves within a conical or dome shaped structure in response to the natural movement of the water to produce a reciprocatory air flow.

The air flow can be used to operate, for example, a turbine-driven electrical generator, to electrolyse sea water, or to pump sea water.

According to the present invention there is provided apparatus for extracting energy from marine sources comprising a hollow generally cone or dome shaped buoyant structure, means for tethering the structure to the bed of a mass of water such that the base of the structure floats on the surface of the mass of water and remains floating at a substantially constant level relative to the still water level of the mass of water, and a flexible member carried within the structure to define a variable volume chamber in the structure, the flexible member being arranged to move in response to the natural movement of the water to vary the volume of the chamber thereby producing a flow of gas or air. The structure is preferably generally cone-shaped and constructed from rigid or semi-rigid material.

The apparatus may include valve means for communicating the chamber to the atmosphere and/or associated equipment.

The flexible member may comprise a membrane which is secured by an air-tight joint to the inner wall of the structure so that at least a substantial portion of the membrane can float on the surface of the mass of water. The membrane may have one or more inflatable regions distributed about its area for adjusting the buoyancy of the membrane.

Alternatively the flexible member may comprise the base of a substantially conical or dome shaped bag disposed within said structure. The upwardly extending wall of said bag may have a number of inflatable ribs adapted to fit into recesses formed in the inner wall of the structure.

The apparatus may include means attached to the base of the structure for stabilising the structure. The stabilising means may comprise a plurality of weighted legs which are adapted to project down into the water.

Alternatively the stabilising means may comprise a cylindrical skirt which is weighted at its lower end.

The tethering means may comprise a chain one end of which is adapted to be secured to the bed of water and the other end of which is connected to a universal joint, and a plurality of equal length lines or chains connecting said universal joint to the structure.

The apparatus may include an inflated belt disposed around the base of the structure.

A plurality of the structures may be provided and coupled to one another to form a single air or gas flow.

The apparatus may have associated equipment responsive to said air for its operation. The associated equipment may be within or outside said structure. The associated equipment may be a turbine driven electrical generator, or electrolysis equipment or a sea water pump.

The invention will be described now by way of example only with particular reference to the accompanying drawings. In the drawings; Figure 1 is a schematic illustration of apparatus according to one embodiment of the present invention; Figure 2 illustrates a tethering arrange ment of the apparatus of Figure 1; and Figure 3 is a schematic illustration of a modification of the embodiment of Figure 1.

The apparatus shown in Figure 1 comprises a hollow conical shaped structure 10 which is tethered to the sea bed by a tethering arrangement 11. The arrangement is such that the base of the structure 10 floats on the surface of the sea 12.

A flexible member in the form of a circular membrane (not shown) is carried within the structure 10 adjacent to its base. The membrane can be formed from material such as neoprene or butadiene which are used in the manufacture of Dracones and hovercraft skirts. The membrane is secured at a suitable height to the inner wall of the structure 10 so that a substantial part of it floats on the surface of the water and forms a variable volume, air tight chamber within the structure. This chamber is provided with one or more valves (not shown) which allow the chamber to communicate with the atmosphere or with associated equipment which will be described later.

A plurality of legs 14 depend from the base of the cone structure 10 into the sea.

The legs 14 are equiangularly spaced around the base and carry weights 15 at their lower ends.

The tethering arrangement 11 comprises a number (one for each leg 14) of flexible lines or chains 18 which extend from the lower end of the legs 14 to a universal joint 19. The universal joint 19 is connected to one end of a flexible chain 20, the other end of which is secured to the sea bed (see Figure 2). The lines or chains 18 are of equal weight and equal length.

The tethering arrangement 11 is so designed that it holds the conical structure 10 at a predetermined level, relative to the long term still water level of the sea. The tethering arrangement has to be able to substantially prevent any upward or downward movement of the conical structure 10 when the level of the sea undergoes short term rises or falls. Additionally the natural buoyancy of the conical structure 10 should be such that the structure 10 does rise upwardly against the pull of the tethering arrangement when the long term level of the sea rises.

In order to achieve this the tethering arrangement 11 should have a weight (in water) which balances substantially the buoyancy of the structure 10 when the structure is floating at the desired level. The tethering arrangement should have sufficient slack to allow for translational movement of the conical structure 10 in response to tidal drift (see Figure 2). As the structure 10 tends to move laterally in response to tidal drift from its position above the anchorage point it will tend to lift the slack in the chain 20, and let it out again when it moves back.

The conical structure 10 carries around its base portion an inflated belt 22. The belt 22 is provided to give the structure 10 its required buoyancy.

The apparatus described above is designed to convert the natural movement of the sea into a flow of air. As the level of the water in the vicinity of the conical structure rises, the membrane will be forced upwardly relative to the structure 10 as the structure is restrained by the tethering arrangement. The volume of the chamber above the membrane is thus decreased and air is forced through the valve or valves associated with the chamber.

When the water level falls the membrane falls with it thereby expanding the chamber.

Air is thus sucked back into the chamber.

This is repeated each time the water level rises and falls. The reciprocatory air movement so created can be used to operate equipment within the conical structure or can be transmitted to operate equipment remote from the conical structure. It will be seen that the water within the conical structure acts in a manner analogous to that of a piston within a cylinder i.e. a water piston. It is envisaged that the membrane could have a cellular or partially cellular structure in which the cells are interconnected by flexible, inflatable tubes or veins. By controlling the degree of inflation of the tubes or veins the buoyancy of the membrane can be varied. The degree of buoyancy can be fixed for a particular membrane or can be variable automatically under the control of appropriate sensing means.

The weighted legs 14 attached to the conical structure are provided to give the structure stability whereby it can remain approximately in the same orientation under substantially all surface conditions. The number of legs required and their weight depends upon the dimensions and weight of the conical structure 10 and its operating environment.

As an alternative to the legs 14 a downwardly depending skirt may be attached to the base of the conical structure 10. This skirt can have a rigid, lattice type construction and be weighted at its lower region. The weight may be a single circumferentially extending member or a number of weights located at angularly spaced positions around the skirt.

In order to prevent any undue rotary motion being imparted to the conical structure 10 by movement of the sea thereby possibly tangling the tethering lines 18, the freedom of the universal joint 19 to rotate in a horizontal plane should be restricted.

It will be appreciated that the conditions under which the apparatus has to operate will vary considerably from very deep water situations with large waves of high frequency and large energy to inshore situations where smaller waves of both higher and lower frequencies occur. The conical structures will have to be made in appropriate sizes and configurations to suit the conditions in which they are to operate and the purpose of their operation.

In order to maximise the movement of the membrane and hence the air flow, it is important to provide the conical structure with sufficient buoyancy that it remains at the desired level relative to the long term level of the sea. This can be achieved by the buoyancy belt 22. The precise position of this belt relative to the structure 10 will depend on the dimensions of the conical structure and its operating environment.

The apparatus described above is basically one for extracting energy from the movement of the sea in the form of air flows i.e. an air pump. A single conical structure has been described but it will be appreciated that several such structures can be used in combination, the structures being linked to give a single combined air flow.

The uses to which the air flows can be put are several and varied. They can be used to actuate devices such as turbine driven electrical generators. Such generators can be located within the conical structure, for example in a chamber in the apex of the cone. The current from the generator could be used to power electrolysis equipment for producing hydrogen from the sea water. It is envisaged that the electrolysis equipment can comprise a number of electrolysis cells which can be housed within a stabilising skirt of the type described above. Furthermore the hydrogen generated by such equipment could be stored temporarily in the buoyancy belt 22 or in the wall of the conical structure if it were of a two layer construction. The hydrogen could then be used to control the buoyancy of the structure 10.Circumstances could arise where the conical structure 10 is filled with hydrogen rather than air, the apparatus working on a closed circuit pumping hydrogen.

Alternatively the air flows may be used to actuate equipment remote from the conical structure 10 and could even be piped ashore. The air flows could also be used to actuate sea water pumps located for example on the sea bed, power being delivered ashore in the form of pumped water.

It should be appreciated that whatever the application of the air flow, the fact that it is of a reciprocatory nature will necessitate one of the following: a) The propellor or turbine driving for example an electrical generator in a conical structure should be such that its rotation is unidirectional irrespective of the air flow direction.

b) The provision of a suitable system of automatically operable air valves to divert the suck and blow air flows through two alternative vents onto one or other of two sets of turbine blades arranged to rotate in opposite directions, or alternatively onto the front and then the rear of just one set of turbine blades.

c) The alternate blowing and sucking effect derived from the water movement should be applied directly or through an appropriate valve system to operate a pneumatic piston system.

In an alternative embodiment shown in Figure 3 the flexible member is provided by the base of a conical, air tight bag 25 which fills the interior of the conical structure 10.

Other integers correspond to those of Figure 1 and are shown by like reference numbers. The bag 25 is constructed in the general shape of the interior of the conical structure 10 from flexible material such as that which has been developed for dracones or hovercraft skirts. It has a number of vertically extending ribs 26 which are inflatable, independently of the inflation of the main bag, to provide the bag with sufficient vertical rigidity. The bag also has one or more circumferential inflatable ribs 28 which are arranged to engage a space between locating ribs suitably formed on the interior of the structure 10 to locate and hold the bag in position. Fastening means are also provided to fasten the bag to the conical structure once the inflated ribs are located in the space between the locating ribs.

The base of the bag 25 is made from highly durable, flexible material. The base moves in a manner corresponding to that described above for the membrane in order to produce the reciprocatory air flows. Connections to convey air flows to and from the bag can be located in the wall of the conical structure with corresponding connections on the bag itself and suitable couplings between the connections. The location of the respective connections depends on the use to be made of the air flows particularly whether they are to be used to operate internal or external equipment.

In one example the main outlet and/or inlet divides into a number of equal diameter tubes or conduits of flexible material which extend down the inside wall of the conical structure, down the stabilising leg 14 or the stabilising skirt into the water and are connected to the lines or chains of the tethering arrangement. The tubes or con duits extend along the chain 20 to a suitable point where they amalgamate into a larger diameter pipe or duct which is connected to the associated equipment.

In a similar manner it may be necessary to combine the air flows from a number of conical structures to provide an increased air flow. The air line from each conical struck ture connects through a suitable automatic valve to one or other of two lines (termed the blow and suck lines). In such circumstances the individual cones receive air through several air lines, not directly from atmosphere but from a common suck line which is connected to atmosphere.

In effect several structures 10 are driving a number of oscillating air columns through several air lines. This can be modified in certain circumstances by suitable valve arrangements so that each individual structure 10 receives air directly from atmosphere, whilst its outward flow is fed into a common air line supplying the associated equipment so that it receives a unidirectional flow.

It will be necessary in the air line system to provide suitable collecting or drain points to accumulate water taken in with the air and for some of the air in the lines to be used periodically to force the accumulated water from the system.

It will be appreciated that the stabilising skirt will prevent debris from floating into the interior of the conical structure and damaging the flexible member.

An advantage of the bag arrangement over the membrane is ease of replacement.

In the event of damage a membrane will be difficult to remove in situ as it is secured to the conical structure. It may require untethering of the whole equipment in order to replace the damaged membrane.

In the case of a damaged bag the ribs can be deflated so that the bag collapses. The bag can be removed from below the base of the conical structure. A new bag can then be inserted under the structure and inflated.

WHAT I CLAIM IS: 1. Apparatus for extracting energy from manne sources comprising a hollow generally cone or dome shaped buoyant structure means for tethering the structure to the bed of a mass of water such that the base of the structure floats on the surface of the mass of water and remains floating at a substantially constant level relative to the still water level of the mass of water, and a flexible member carried within the structure to define a vari; able volume chamber in the structure, the flexible member being arranged to move in response to the natural movement of the water to vary the volume of the chamber thereby producing a flow of gas or air.

2. Apparatus as claimed in Claim 1, wherein said structure is generally coneshaped and is constructed from rigid or semi-rigid material.

3. Apparatus as claimed in Claim 1 or Claim 2, wherein said chamber includes valve means for communicating said chamber to the atmosphere or associated equipment.

4. Apparatus as claimed in any preceding claim, wherein said flexible member comprises a membrane which is secured at suitable height by air-tight jointing to the inner wall of the structure so that at least a substantial portion of the membrane can float on the surface of the mass of water.

5. Apparatus as claimed in Claim 4, wherein said membrane has one or more inflatable regions distributed about its area for adjusting the buoyancy of the membrane.

6. Apparatus as claimed in any one of claims 1 to 3, wherein said flexible member comprises the base of a substantially conical or dome shaped bag disposed within said structure.

7. Apparatus as claimed in Claim 6, wherein the upwardly extending wall of said bag has a number of inflatable ribs adapted to fit into recesses formed in the inner wall of the structure.

8. Apparatus as claimed in any preceding claim, including means attached to the base of the structure for stabilising the structure.

9. Apparatus as claimed in Claim 8, wherein said stabilising means comprises a plurality of weighted legs which are adapted to project down into the water.

10. Apparatus as claimed in Claim 8, wherein said stabilising means comprises a cylindrical skirt which is weighted at its lower end.

11. Apparatus as claimed in any preceding claim, wherein said tethering means comprises a chain one end of which is adapted to be secured to the bed of water and the other end of which is connected to a universal joint, and a plurality of equal length lines or chains connecting said universal joint to the structure.

12. Apparatus as claimed in any preceding claim, including an inflated belt disposed around the base of the structure.

13. Apparatus for extracting energy from marine sources comprising a plurality of the structures claimed in any preceding claim said structures being coupled to one another to form a single air or gas flow.

14. Apparatus as claimed in any preceding claim, including associated equipment responsive to said air flow for its operation.

15. Apparatus as claimed in Claim 14, wherein said equipment is disposed within said structure.

16. Apparatus as claimed in Claim 14, wherein said equipment is disposed outside

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. duits extend along the chain 20 to a suitable point where they amalgamate into a larger diameter pipe or duct which is connected to the associated equipment. In a similar manner it may be necessary to combine the air flows from a number of conical structures to provide an increased air flow. The air line from each conical struck ture connects through a suitable automatic valve to one or other of two lines (termed the blow and suck lines). In such circumstances the individual cones receive air through several air lines, not directly from atmosphere but from a common suck line which is connected to atmosphere. In effect several structures 10 are driving a number of oscillating air columns through several air lines. This can be modified in certain circumstances by suitable valve arrangements so that each individual structure 10 receives air directly from atmosphere, whilst its outward flow is fed into a common air line supplying the associated equipment so that it receives a unidirectional flow. It will be necessary in the air line system to provide suitable collecting or drain points to accumulate water taken in with the air and for some of the air in the lines to be used periodically to force the accumulated water from the system. It will be appreciated that the stabilising skirt will prevent debris from floating into the interior of the conical structure and damaging the flexible member. An advantage of the bag arrangement over the membrane is ease of replacement. In the event of damage a membrane will be difficult to remove in situ as it is secured to the conical structure. It may require untethering of the whole equipment in order to replace the damaged membrane. In the case of a damaged bag the ribs can be deflated so that the bag collapses. The bag can be removed from below the base of the conical structure. A new bag can then be inserted under the structure and inflated. WHAT I CLAIM IS:

1. Apparatus for extracting energy from manne sources comprising a hollow generally cone or dome shaped buoyant structure means for tethering the structure to the bed of a mass of water such that the base of the structure floats on the surface of the mass of water and remains floating at a substantially constant level relative to the still water level of the mass of water, and a flexible member carried within the structure to define a vari; able volume chamber in the structure, the flexible member being arranged to move in response to the natural movement of the water to vary the volume of the chamber thereby producing a flow of gas or air.

said structure.

17. Apparatus as claimed in Claim 14, wherein said associated equipment is a turbine driven electrical generator, or electrolysis equipment, or a sea water pump.

18. Apparatus substantially as hereinbefore described with reference to and as shown in Figures 1 and 2 or Figure 3 of the accompanying drawings.