GB2397625A

GB2397625A - Energy generator using tidal motion

Info

Publication number: GB2397625A
Application number: GB0301451A
Authority: GB
Inventors: Roger Errol Doucy
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-01-22
Filing date: 2003-01-22
Publication date: 2004-07-28
Also published as: GB0301451D0; GB0307631D0

Abstract

An energy generating device converts the linear motion of the tides to rotational motion to generate electricity. The device comprises a floating body 10 connected through a convertor means, gearbox and clutch to the generator. The convertor means may comprise a toothed mast 14 on the floating body 10 which engages with and rotates a toothed cog. The gearbox 34 may include a changeover gearbox 36 to control the direction of the rotational motion and a planetary type gearbox 34, and the clutch 38, which may be electromagnetic, may be operated by a timer switch in order to engage/disengage the convertor means from the generator.

Description

EneraY Generator The present invention relates to a method and apparatus

for generating electrical energy from a sustainable supply.

It is well recognized that electrical energy generation from fossil fuels is not ideal, due to pollution created by the use of the fossil fuel and the fact that the supply of fossil fuel will not last indefinitely.

There have been many attempts of varying success to harness and convert energy from waves, wind and other sustainable sources. For example, wind turbines are becoming more commonplace despite there being some environmental impact perceived to occur with such turbines.

The present invention seeks to provide electrical energy generation from tidal motion.

According to a first aspect of the present invention there is provided a device for generating electrical energy from the motion of a floating body, the device comprising the floating body connectable to generator means via: a) convertor means to convert linear motion to rotational motion; b) gearbox means linked to said convertor means to control said rotational motion; and c) clutch means to engage/disengage the generator from the floating body.

The invention thus provides apparatus that converts the vertical linear motion of the floating body rising and falling due to the tide into a rotational motion which drives the generator means. It will be appreciated that the tidal motion is slow, having a typical period of about 12 hours. The gearbox means is, inter alla, included to increase the speed of rotation for the generator means. The clutch is required so that the floating body and the generator means do not act against one another when the tide turns as this would cause damage and waste significant amounts of the generated energy.

Thus, the invention concerns an electrical energy generator which converts the vertical motion of a floating body docked in tidal waters into a rotational motion used to drive an alternator for the electricity production.

Normally the gearbox means contains a first gearbox with a gearbox ratio of at least 1:50, preferably 1:500, more preferably about 1:5,000. The gearbox will then increase the speed of rotational motion by the gearbox ratio. It is likely the first gearbox will be a planetary gearbox and these are suitable for transmitting very high torque and achieving the desired gearbox ratios.

Advantageously, the gearbox means will further comprise a changeover gearbox for controlling the direction of said rotational motion. By introducing the changeover gearbox, the rise and fall of the floating body can be used to drive the generator means, ie the generator means is substantially constantly driven. Otherwise the floating body would have to remain disconnected from the generator for either the rise or the fall.

In one preferred embodiment the floating body is linked to said planetary gearbox, and said planetary gearbox is linked to said changeover gearbox which is linked to said generator means.

Normally the clutch means includes a first clutch located between said floating body and said gearbox means, and/or said clutch means includes a second clutch located between said gearbox means and said convertor means. It is preferred for both the first and second clutch means to be included. The first clutch means allows disconnection of all the gearboxes and generating apparatus from the floating body during a tide change and allows, eg, for the changeover gearbox to be switched. The second clutch means isolates the gearboxes from the generator means thus allowing the momentum of the generator to be conserved and used to assist when the clutches are disengaged.

The clutches contained in the clutch means conveniently comprises electromagnetic clutches. Such electromagnetic clutches are simple to control whilst being capable of handling the very high torque transmitted in the present invention.

A float switch will normally be provided to control the engagement/disengagement of said clutch means, and/or a timer switch controls the engagement/disengagement of said clutch means. These may be used during changes of the tides direction. The clutches may also be used to isolate the components during maintenance operations.

The generator means normally comprises an alternator linked to a flywheel. This is a well established and reliable way to use rotation motion to generate electricity.

The alternator will advantageously rotate unidirectional as the floating body ascends and descends due to tidal changes.

The convertor means may comprise a toothed mast fixed to said floating body which engage with and rotate a respective toothed cog as the floating body ascends and descends due to tidal changes.

The mast is located within one or more mast guides positioned on or in the floating body. These guides allow the mast to be reliably fixed to the floating body whilst permitting easy maintenance of the apparatus.

It is preferred for retaining means to be provided on said mast for retaining said mast in said mast guide(s) as said floating body moves upwardly or downwardly.

In one embodiment, said mast is urged into said mast guide by a ram, eg a hydraulic ram. This can allow for slight horizontal movements of the floating body relative to the convertor means without causing damage of accidental disengagement. The rams can be employed to intentionally cause disengagement for maintenance or in adverse weather conditions.

The teeth on the mast are advantageously provided as several tooth sections. This allows replacement of short sections when these are worn. The mast will be provided with the toothed extent being of sufficient length to cater for the maximum anticipated tide, but the most wear will occur on the centre extent of the toothed section as the tides will normally be much less than the anticipated maximums.

The floating body may be coupled to one or more guide rails located on a dockside, or other fixed structure wherein said coupling permits ascent and descent of said floating body and restricts angular motion of said floating body. Furthermore, the floating body may be provided in a harbour to reduce the effects of inclement weather on the device.

According to a second aspect of the present invention there is provided a method of generating electrical energy, the method comprising the steps of: a) providing a device according to said first aspect; and b) floating said floating body in tidal waters.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a cross-section through a first embodiment of the present invention; Figure 2 is a view on 'A-A' of Figure 1; Figure 3 is an enlarged view of Detail tA' shown in Figure 1; Figure 4 is an enlarged view of Detail 'B' shown in Figure 1; Figure 5 are enlarged views of Detail 'C' shown in Figure 1; Figure 6 is an enlarged view of Detail 'D' shown in Figure 1; Figure 7 is an enlarged view of Detail 'E' shown in Figure 1; Figure 8 is an enlarged view of Detail 'F' shown in Figure 1; and Figure 9 are enlarged views of Detail 'G' shown in Figure 2.

The invention provides an apparatus to change the vertical rising and falling action of the tide into a rotating action that is used to generate electricity.

A preferred embodiment of the invention will now be described with reference to the drawings. The apparatus, as illustrated in the accompanying drawings, comprises a large floating prime mover or floating body 10, such as a ship or barge. This prime mover 10 is attached to a dockside or fixed structure 40, such as a jetty, by stabilisers 12 and possibly within a harbour or lagoon (not shown).

Solid masts 14, with suitable toothed attachments provided as segments 16 shown in Figure 3. The masts 14 are located at intervals through the deck to the base of the prime mover 10. The masts 14 are pushed into a back stop and mast guide 16a, 16b by respective hydraulic rams 18a, 18b both at the base (inside) the prime mover 10 and on the deck thereof.

Above, positioned on a gantry, is another hydraulic ram 18c, which has fixed to its moveable end, another mast guide 16c. This guide 16 is pushed to within 2-3 mm of the mast 14 and the guide 16 is suitably coated inside with grease.

The bottom of the mast 14 has ears welded thereto. The ears are positioned within guides 16a which prevent the mast 14 from pulling upwards when the tide is falling.

Detail B is shown in Figure 4. A steel three sided box 50 is fixed to the end of the moveable shaft of hydraulic ram 18c. The ram 18c itself is mounted on a platform, protruding from the dockside or jetty 1. The moveable box section 50 is pushed and pulled to and fro in horizontal guides, so that it will tend to keep the mast 14 in the vertical position whilst the mast is engaged with the cog of the electromagnetic clutch 18, and still vertical when the mast 14 is pulled away for maintenance purposes.

The steel box 50 will be coated inside with grease to allow the vertical motion of the mast 14 relatively easy passage during its operation. The grease can be topped up or replaced easily at any tide change when the mast 14 will be stationary for a short period of time.

Detail C is shown in Figure 5 which shows a three-side steel box 16b welded to the deck and supported by triangular steel struts, which, in turn are welded to each side of the box 16b and to the deck.

This box 16b acts as a back stop for the mast 14 when in operating position. It also acts as a guide when hydraulic ram 18b pulls the mast 14 free from the operating position to the maintenance position. Detail D shown in Figure 6 shows further details of the connection between mast 14 and hydraulic ram lab.

Detail E is shown in Figure 7 and shows a guide/support 16a similar in construction to that shown in detail C only much larger in construction. This acts to give the mast 14 as much support as possible when the hydraulic ram 18a operates and pushes the mast 14 into its operating position.

It also acts as a guide when ram 18a pulls the mast into the maintenance position.

Detail F is shown in Figure 8. Detail F shows the ears 14 a welded to the mast 14 and are retained in the slots at the base of the box 16a, which prevent the mast 14 from being pulled upwards when the tide is falling.

Detail G is shown in Figure 9. Detail G shows a typical retaining mechanism fixed to the deck of the prime mover 10 and protruding to the dockside wall or jetty support structure.

Vertical guides are fixed to the wall. These retain the wheels, which will roll up and down the wall with the rise and fall of the tide. They will keep the prime mover in a vertical mode, therefor nullifying any angular forces that might otherwise cause the mast and cog to disengage.

Method of Generating electricity As the tide rises the prime mover 10 rises and each toothed masts rises and turns respective cog 30. The associated shaft 32 then turn the cogs in the planetary gearbox 34. Suitable planetary gearboxes are known in the art, with gearbox ratio of about 1:5000. The planetary gearbox 34 converts the very slow turning of its input shaft 32, into suitable revolutions per minute, required by the alternator 40.

Any type of gearbox could be used in the invention.

However, a helical gearbox is likely to be overly massive if constructed with the necessary characteristics. In the illustrated embodiment the planetary gearbox 34 is designed to transmit at least 1,OOO,OOONm torque. The input speed on a three metre tide is around O.lrpm. The planetary gearbox output is about 500rpm. Suitable planetary gearboxes can be provided by either Flender or Brevini.

The changeover gearbox 36 is preferentially located after the planetary gearbox 34 as suitable units are available which work at the output speed of the planetary gearbox 34.

The illustrated alternator 40 is a Le Roy Somer unit designed to output 25 megawatts at an input speed of about 500rpm. Similar alternators can also be sourced elsewhere, such as from Hitzinger. - 9 -

If different power output was desired the alternator can be changed accordingly. If a lower output was wanted, it is likely that the nominal input speed would need to be increased. Many available alternators would require an input speed of about 1500rpm. The planetary gearbox 34 would be altered to provide the necessary output speed.

Although, the gearbox ratio may need to be increased, it is likely that the torque transmitted would be reduced as the generator would not be as difficult to move.

In the illustrated embodiment, the device is configured to produce electricity at 11,000 volts and an output power of 25 megawatts (per mast) . The illustrated embodiment depicts 4 masts, therefore giving an output of 100 megawatts at 11,000 volts. Suitable alternators are known, eg from Le Roy Somer. More masts could be added, depending on the size of the prime mover 10 and the required energy output.

When the tide has reached its highest point (detected by float switches and timers (not illustrated)), both of the electromagnetic clutches 38 open. Once opened, the flywheel 42 maintains the alternator 40 output until the tide has turned. At this point the changeover gearbox 36 is signalled so that when the downward motion of the mast 14 turns the cog on the first clutch 38 in the opposite direction, the electromagnetic clutches 38 both close. The alternator 40 rotates unidirectional in this manner.

During the period when the planetary gearbox 34 is disengaged from the mast, the gearbox 34 will stop rotating due to frictional loss therein. When the drive is re engaged the planetary gearbox 34 is then turned in the opposite direction.

The illustrated embodiment is designed to incorporate several nonessential but desirable features, eg for maintenance purposes.

To replace any worn sections of teeth on the masts, the hydraulic rams 18 are operated to pull the masts 0.5m away from the cog. The rams are interlocked so they operate in a safe manner. The toothed section of the mast 14 is in suitable handleable sections that can be interchanged with other sections (which may be less worn) or with new replacement sections.

The use of electromagnetic clutches 38 to disengage the gearbox 34, 36 from the alternator 40, will also allow maintenance / overhaul / replacement of any of the gearbox 34, 36 alternator 40 and flywheel 42 parts and the replacement / overhaul of the hydraulic rams 18 and their parts.

It will be appreciated that the invention has several distinct advantages. Since there is no fuel, there is no pollution i.e. no sulphurous gases, no nuclear waste, no chemical spillage's, no unsightly chimneys of 650 feet and over, no piles of coal, no oil storage tanks, therefore no large lorries, trains or ships transporting fuel. This represents a safer and cleaner environment.

With minimal architectural input these plants could be made aesthetically pleasing.

The power generated by these plants could be fed into step up transformers for the supply of power to inland areas, eg via present pylon systems.

Calculations have been based on a minimum tidal movement of three metres or above. Therefore these fuel free power plants can be located at many sites up and down most large rivers and around many coastlines.

Claims

Claims: 1. A device for generating electrical energy from the motion of a

floating body, the device comprising the floating body connectable to generator means via: a) convertor means to convert said linear motion to said rotational motion; b) gearbox means linked to said convertor means to control said rotational motion; and 10c) clutch means to engage/disengage the generator from the floating body.
2. A device according to claim 1, wherein the gearbox means includes a gearbox with a gearbox ratio of at least 151:50, preferably 1:500, and more preferably about 1:5,000.
3. A device according to claim 2, wherein the gearbox is a planetary gearbox.
204. A device according to any preceding claim, wherein the gearbox means includes a changeover gearbox for controlling the direction of said rotational motion.
5. A device according to all of the preceding claims, wherein said floating body is linked to said planetary gearbox, and said planetary gearbox is linked to said changeover gearbox which is linked to said generator means.
6. A device as claimed in any preceding claim, wherein said clutch means includes a first clutch located between said floating body and said gearbox means.
7. A device as claimed in any preceding claim, wherein said clutch means includes a second clutch located between said gearbox means and said convertor means.
8. A device as claimed in any preceding claim, wherein said clutch means comprises electromagnetic clutch means.
9. A device as claimed in any preceding claim, wherein a float switch controls the engagement/disengagement of said clutch means.
10. A device as claimed in any preceding claim, wherein a timer switch controls the engagement/disengagement of said clutch means.
11. A device as claimed in any preceding claim, wherein said generator means comprise an alternator linked to a flywheel.
12. A device as claimed in claim 11, wherein the alternator rotates unidirectional as the floating body ascends and descends due to tidal changes.
13. A device as claimed in any preceding claim wherein said convertor means comprises a toothed mast arranged on said floating body which engage with and rotate a respective toothed cog as the floating body ascends and descends due to tidal changes.
14. A device as claimed in claim 13, wherein said mast is located within one or more mast guide positioned on or in the floating body.
15. A device as claimed in either claim 13 or claim 14, wherein retaining means are provided on said mast for retaining said mast in said mast guide as said floating body moves upwardly or downwardly.
16. A device as claimed in any of claims 13 to 15, wherein said mast is urged into said mast guide by a ram.
17. A device as claimed in claim 16, wherein the ram is a hydraulic ram which can be operated to move the mast away from said convertor means for maintenance.
18. A device as claimed in anyone of claims 13 to 17, wherein the mast is provided with a plurality of separate tooth sections.
19. A device as claimed in any preceding claim, wherein said floating body is coupled to one or more guide rail located on a dockside, or other fixed structure wherein said coupling permits ascent and descent of said floating body and restricts angular motion of said floating body.
20. A method of generating electrical energy, the method comprising the steps of: a) providing a device according to any one of claims 1 to 19; and b) floating said floating body in tidal waters.
21. A device substantially as hereinbefore described with reference to and/or as illustrated in the accompanying drawings.
22. A method of generating energy as hereinbefore described with reference to and/or as illustrated in the accompanying drawings.