GB2085974A

GB2085974A - Apparatus for obtaining energy from water power, eg of the sea

Info

Publication number: GB2085974A
Application number: GB8034341A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-10-24
Filing date: 1980-10-24
Publication date: 1982-05-06

Abstract

The apparatus comprises a float 6 and counterbalancing means 10 therefor both reciprocable vertically, the counterbalancing means being connected to at least one ratchet drive bar 14 cooperating with a ratchet wheel 15 so as to drive the latter on reciprocating movement of the float due to rise and fall of the level of the body of water 1. The wheel 15 may drive a compressor 17 which discharges to a store 25, and the compressed air from the store may be used to drive a generator 29 via a buoyancy energy machine 28. The latter comprises a submerged wheel rotated by successive inflation and exhaustion of buoyancy bags attached to the periphery of the wheel. <IMAGE>

Description

SPECIFICATION Apparatus for obtaining energy from water power The present invention relates to apparatus for obtaining or collecting energy from the power exhibited by moving water and, particularly, for obtaining energy from the power of the sea.

There are three possible sources of motion to consider when deriving energy from the movement of the sea, namely, (i) the rise and fall of the tide, (ii) wave motion and (iii) surge motion resulting from ebb and flow of the tide. Each of these movements can be harnessed to produce energy. By simple calculation, it can be shown that the rise and fall of the tide can effectively be ignored as an energy source, but must be considered as a serious handicap to design of suitable apparatus for obtaining energy from sea power, and that the other two movements, that is (ii) and (iii) mentioned above, are more effective as an energy source.It has been found that wave motion and surge motion combine most effectively to provide optimum rise and fall motion against a vertical obstruction, for example, a cliff face, and if this condition is not available naturally, then it may be provided artificially. Another important consideration is the corrosive effect of sea water and the necessity of having the level of water at low tide (when the energy collecting apparatus must also operate) as near as possible to the building where the collected energy can be utilized.

With the above in mind, it is an object of the present invention to provide apparatus for obtaining or collecting energy from water power primarily resulting from wave motion and/or surge motion.

The present invention consists in apparatus for obtaining energy from water power, comprising a float for floating on water, counterbalancing means connected to the float by a flexible member in such a manner that the float is reciprocable along a substantially vertical path in response to movement of the water, said counterbalancing means exerting a counterbalancing force on the float of less than the weight of the float, and mechanism coupled to the assembly of the float and counterbalancing means for converting the reciprocating motion of the float into energy.

Ideally, the apparatus of this invention is installed close to a cliff face which is as near vertical as possible with the float floating on the water adjacent the cliff face. In tidal areas, the site should be selected or prepared so that the float remains floating at low tide and whatever the water conditions. The counterbalancing means and converting mechanism may be installed in a building close to the cliff top so as to maintain the length of the flexible member as short as possible.

Alternatively, in the absence of an ideal cliff site, a suitable site may be prepared by constructing a retaining wall where the water is of appropriate depth and in-filling behind the retaining wall. The float is then disposed on the water in front of the retaining wall and the building containing the counterbalancing means and converting mechanism may be constructed behind the retaining wall either on the shore or on the in-fill, if suitably prepared. Whether the apparatus is installed on a cliff or other site, the float may be suspended on a length of the flexible member guided about a support mounted vertically above the float and the flexible member should not exceed a certain maximum length which will have to be determined by experiment.The gradient of the sea bed in front of the cliff or retaining wall should also have a minimum value of the order of 1 in 5 for optimum results.

Conveniently, the counterbalancing means comprises a counterweight which is also arranged to be reciprocable along a substantially vertical path in response to vertical reciprocating motion of the float. The counterweight is preferably in the region of half the weight of the float. Suitable guide means may be provided for guiding the movement of the float and/or counterweight along their respective vertical paths. The guide means advantageously avoids the use of runners or other moving parts.

The float may be a hollow body of spherical or cylindrical shape. Optimum results may be obtained with a cylindrical float since this requires a lesser area of water and can more readily be guided or constrained for vertical movement.

The mechanism for converting the reciprocating motion of the float into energy may comprise at least one ratchet drive bar connected to the assembly of the float and counterbalancing means and arranged to cooperate with a ratchet wheel, whereby the wheel is turned in one direction in response to reciprocating movement of the float. Preferably, the assembly is connected to actuate two ratchet drive bars cooperating with two ratchet wheels so that the wheels are successively turned in opposite directions in response to reciprocating movement of the float. The or each ratchet drive must be of a length at least equal to the difference between the extreme tide levels plus the anticipated wave amplitude in the most severe conditions. The or each ratchet wheel should have as large a radius as practically possible.

Since to be practical the apparatus should operate at a constant output in all weather conditions ranging from extreme calm to near hurricane, provision may be made for storing the energy output from the converting mechanism. An average condition can only be deter mined by experiment and energy obtained above that average condition may be stored for use when conditions are below the average. One convenient way of storing the energy is in the form of compressed air. Hence, the ratchet wheels may be connected to drive air compressing means and the compressed air produced may be delivered to a storage tank or chamber from which it may be withdrawn for use in driving an electrical generator or other machinery.One suitable form of machine for use with the present invention is a buoyancy energy machine in which the compressed air is utilized to fill buoyancy bags on the periphery of a wheel submerged in a tank of water, the wheel being caused to rotate and produce a rotary drive by successively inflating the buoyancy bags adjacent the lowest point on the wheel and exhausting them adjacent the highest point. This wheel may be arranged to drive a generator.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Figure 1 is a diagrammatic view of one embodiment of the invention, Figure 2 is a fragmentary plan view of the float, Figure 3 is a fagmentary perspective view of the counterweight and ratchet drive mechanism, and Figures 4 and 5 are respectively a vertical section and a plan view of a buoyancy energy machine which may be driven by the apparatus of this invention.

Referring to Fig. 1 of the drawings, the apparatus is installed on a site adjacent the edge of the sea 1. It is installed behind a retaining wall 2 constructed at a predetermined distance from the shore where a sufficient depth of water exists at low tide so that the float remains floating at low tide without grounding on the sea bed 3 even under the most severe rough water conditions. The space behind the retaining wall is filled in with rock and soil 4 so as to provide suitable foundations for a building 5 housing the apparatus and constructed adjacent the retaining wall 2.

The apparatus comprises a float 6 floating on the sea adjacent the front of the retaining wall 2 and constrained to move along a substantially vertical path by a guide cage 7 secured to the front face of the retaining wall.

The float is a hollow steel body of generally cylindrical shape and in order that the apparatus may have an adequate power output, it should weigh 20,000 Ibs or more. The cage 7 is constructed of steel bars 8 (Fig. 2) sheathed in suitable plastics material and the float has two projecting buffer rings 9 also made of plastics material which minimize friction when surge motion forces the float against the walls of the cage.

The float is connected to a counterweight 10, housed in the building 4 and also constrained for movement-along a substantially vertical path, by a flexible member 11 in the form of a nylon or other cable supported by a series of pulleys 1 2. The counterweight 10 is half the weight of the float so that the water displacement of the float is equal to half the weight of the float, or the full weight of the counterweight, and rise and fall, reciprocating movement of the float in response to wave or surge motion of the sea is transferred to the counterweight. The counterweight is partially housed in a pit 13 in order to reduce the height of the building 4.

The counterweight 10 is in the form of a horizontal bar which has a pair of ratchet drive bars 14 fastened to one side (Fig. 3).

These ratchet drive bars engage with two ratchet wheels 1 5 rotatably mounted within the building 4, the ratchet teeth on one cooperating bar and wheel 14, 1 5 being arranged to drive the associated wheel in one direction, upon reciprocating motion of the float 6, and those on the other bar and wheel being arranged to drive the associated wheel in the opposite direction. The ratchet bars are of a length equal to the difference in height between the highest and lowest tides plus the anticipated maximum wave amplitude in the roughest sea conditions so that the bars remain in engagement with their associated ratchet wheels at all states of the tide and under all sea conditions. The radii of the ratchet wheels should be made as large as is practically possible, for example, of the order of 1 5 ft.

The counterweight 10 is constrained to move along its vertical path by guide channels 1 6 engaging opposite ends of the counterweight bar.

Each ratchet wheel 1 5 is connected to drive a single cylinder air compressor 1 7. To this end, the ratchet wheel is connected to the crank shaft 1 8 of the compressor by a chain drive comprising sprocket wheels 19, 20 secured respectively to the axle of the ratchet wheel and the crank shaft, and a chain 21.

The crank shaft 1 8 is connected to the piston 22 in the compressor cylinder 23 by a connecting rod 24 and rotation of the crank shaft reciprocates the piston within the cylinder in order to compress air which is delivered to a storage tank chamber 25 via a line 26. Compressed air can be withdrawn, as required, from the storage tank under the control of a valve 27 and supplied to a buoyancy energy machine 28 arranged to drive an electrical generator 29.

Referring to Figs. 4 and 5, the buoyancy energy machine 28 comprises a wheel 30, for example 33ft. in diameter, rotatably mounted on a horizontal shaft 35 in a tank 31 and submerged in water 32 contained in the tank.

Mounted about the periphery of the wheel 30 are inflatable bags 33, for example, made from reinforced polythene material, which are successively inflated and exhausted in order to rotate the wheel. The bags are arranged to be inflated as they pass the lowest point of the wheel and are exhausted adjacent the highest point on the wheel, which is just below the surface of the water in the tank, with the aid of rollers 34 mounted at the top of the wheel and arranged to collapse the bags and exhaust air from the latter. In Fig. 4, the wheel 30 rotates in a clockwise direction and the inflatable bags are inflated as they enter the lower left-hand quadrant and are exhausted as they leave the upper left-hand quadrant in order to produce this direction of rotation.

The shaft 35 mounting the wheel extends through sealed bearings 36 in opposite sides of the tank and the wheel and shaft contain passageways and suitable valving (not shown) for delivering compressed air to and exhausting air from the bags. The passages in the shaft are connected to the control valve 27 and the compressed air storage tank 25 via a rotary valve 37 which also serves to control supply of compressed air to the bags and exhaust of the bags in the appropriate sequence to provide for rotation of the wheel in the required direction. The shaft 35 may be coupled to the generator 29 in any convenient manner, such as by a sprocket and chain drive 38 (Fig. 1), in order to drive the generator.

Whilst particular embodiment has been described, it will be understood that modifications can be made without departing from the scope of the invention. For example, whilst only one float 6 and associated mechanism has been described for supplying compressed air to the storage tank 25, it will be appreciated that a series of floats may be disposed along the retaining wall and be connected to further mechanisms, similar to that described above, for producing compressed air and delivering it to the storage tank.

Claims

1. Apparatus for obtaining energy from water power, comprising a float for floating on water, counterbalancing means connected to the float in such a manner that the float is reciprocable along a substantially vertical path in response to movement of the water, said counterbalancing means existing a counterbalancing force on the float of less than the weight of the float, and mechanism means for converting the reciprocating motion of the float into energy.

2. Apparatus as claimed in claim 1, wherein the counterbalancing means comprises a counterweight which is also arranged to be reciprocable along a substantially vertical path in response to vertical reciprocating motion of the float.

3. Apparatus as claimed in either claim 1 or claim 2, wherein the counterweight is approximately half the weight of the float.

4. Apparatus as claimed in either claim 2 or claim 3, wherein guide means are provided for guiding the movement of the float and/or counterweight along their respective vertical paths.

5. Apparatus as claimed in claim 4, wherein the guide means avoids the use of runners on the other moving parts.

6. Apparatus as claimed in any one of the preceding claims wherein the float is a hollow body of spherical or cylindrical shape.

7. Apparatus as claimed in any one of the preceding claims wherein the mechanism for converting the reciprocating motion of the float into energy comprises at least one ratchet drive bar connected to the assembly of the float and counterbalancing means and arranged to cooperate with a ratchet wheel, whereby the wheel is turned in one direction in response to reciprocating movement of the float.

8. Afpparatus as claimed in claim 7, wherein the assembly is connected to actuate the ratchet drive bars cooperating with two ratchet wheels so that the wheels are successively turned in opposite directions in response to reciprocating movement of the float.

9. Apparatus as claimed in any one of the preceding claims including means for storing the energy output of the converting means.

1 0. Apparatus as claimed in claim 9, wherein the storing means utilises, in operation, compressed air.

11. Apparatus according to claim 10, when dependent on either of claims 7 or 8, wherein the wheel or wheels is/are connected to drive air compressing means for supplying compressed air to a storage tank or chamber.

1 2. Apparatus as claimed in claim 11, including a buoyancy energy machine operative to utilise the compressed air in said storage tank or chamber, the machine comprising buoyancy bags on the periphery of a wheel submergable in a tank of water, the wheel in use being caused to rotate and produce a rotary drive by the successive inflation of the buoyancy bags on the lowest point of the wheel with compressed air from said stoage tank or chamber, and exhaustion of the bags adjacent the highest point.

1 3. Apparatus for obtaining energy from water power substantially as hereinbefore described with reference to the accompanying drawings.