WO2008104024A1

WO2008104024A1 - Electricity generation device

Info

Publication number: WO2008104024A1
Application number: PCT/AU2008/000254
Authority: WO
Inventors: Michael Dileo
Original assignee: Michael Dileo
Priority date: 2007-02-28
Filing date: 2008-02-28
Publication date: 2008-09-04
Also published as: AU2007200888B1

Abstract

An electricity generation device (10) for generating electricity from the flow of water, such as tidal flow, the device including: turbine means (4) such as a rotary turbine displaceable by the water flow to move a transmission means (51) operably connected to an electricity generator (50); and water flow guidance means (31) such as guide walls to direct the water approaching the device at an approach velocity towards the turbine means, whereby, the turbine contacting water immediately before the water moves past the turbine means has an increased speed of water flow relative to the approach velocity and/or an increased water pressure relative to the approaching water.

Description

Title Electricity Generation Device

FIhLD Ol- INVhN 11ON

This invention relates to an electricity generation device. More particularly, this invention relates a tidal electricity generation device.

5 BACKGROUND ART AND DISCUSSION

The following references to and descriptions of prior proposals or products are not intended tυ be, and are no( to be construed as, statements or admissions of common general knowledge in the art. Tn particular, the following prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in o the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

Accordingly, an object of the present invention is to ameliorate the aforementioned disadvantages of the prior art or to at least provide a useful alternative thereto.

F.lcctricity power generation using renewal energy resources is highly desirable in the5 context of the inevitable exhaustion of non-renewal energy resources such as oil, coal and natural gas. Hydroclcctricity generation plants utilising the potential energy from elevated catchments of water to drive turbines has been demonstrated to be a reliable, if limited, method of generating electrical power. ITydroelectricily schemes in Australia include the Snowy River Scheme and the Tasmanian Hydroclcctricity plants, for0 example at Lake Pedder. However, such schemes are entirely reliant on the availability of large bodies or volumes of high altitude water subject to significant altitude drops to create the potential energy required and are therefore reliant on the exploitation of limited natural geographic formations.

By contrast, tidal power is more widely available on many coastlines, particularly those with a high potential head or difference in water levels between low and high tides. Although the nature of tidal flows means that most tidal powered generations schemes can produce only intermittent power due to "downtime" on the turning of the tides, technologies have been described that alleviate this problem to deliver a continuous supply. However, take up of tidal electricity generation technology has been slow and there has generally been less acceptance of tidal technologies, compared to wind farm technology which is not only intermittent, but unreliable. This is primarily due to two factors:

1. I he large and expensive infrastructure including caissons, sluices and ship locks where barrages arc used to close off a bay; and

2. The relevantly low yields of energy available from the slow moving and massive volumes of water typically involved.

STAT¹RMRNT OF INVENTION Accordingly, the invention provides in one aspect an electricity generation device to generate electricity from both incoming and outgoing tidal flows of water, said device including: power translation means at a centralised location, said power translation means displaceable by water flow to move a transmission means operably connected to a electricity generator; and water flow guidance means having at least one wall made from substantially inflexible material and inclined towards said centralised location, and a ceiling generally aligned in non-parallel relationship to at least one wall of the water flow guidance means, said water flow guidance means operable to corral the water approaching said device at an approach velocity towards said power translation means at said centralised location. wherein the water immediately preceding said power translation means has increased velocity relative Io the approach velocity and an increased water pressure relative Io thai of the approaching water.

The power translation means may be adapted to translate the linear motion of the flowing water into rotational motion. lTie power translation means is preferably a turbine means.

The water may be part of a large body of water, such as ocean, bay. estuary or lagoon. Preferably, the body of water is a bay opening to the sea through a narrow gap and having a large potential bead, i.e. large lidal drop from high to low tide. Heads of 8- 1 Om arc preferred. In any case, the present invention is also applicable to any reasonably large body of water that can provide intermittent or permanent fast running water, such as may be found in rivers and dam outlets.

The device may be a portable, movable or fixed structure or installation and may be in the form of a plant. The plant may be a fixed installation permanently built in situ. The plant may be built using prefabricated structures, such as concrete slabs and may include a steel or other metal alloy irame structure. Preferably (he steel material is marine grade steel and/or is augmented with oxygenation sacrifice materials to resist the effects of corrosion, particularly in a marine or brackish environment Preferably, the plant is a stand alone unit that may be relocatable once assembled. The stand alone unit may be fixed to a particular location by flexible lengths, such as rope, chain or cable. Alternatively, the plant may be anchored using inflexible lengths, such as metal, wooden, concrete or other rigid materials to set the plant in position. Preferably, flexible lengths arc used to allow some play to permit the plant to orientate according to the water flow direction.

The plant may comprise a platform or frame from which depend the guidance means. 5 I he turbine means may be installed as a fixed installation or may be adapted to swivel or otherwise move to accommodate a change in water flow direction relative to the platform. I he electricity generation means may be located on or otherwise attached to the platform. The guidance means may be adapted to increase the water pressure of the approaching water as it approaches the turbine means. The guidance means may0 include a wide mouth remote from the turbine means. The guidance means may include a narrow throat close to the turbine means. The wide month and narrow throat may combine to form a large funnel directed Io the turbine means. The guidance means may include at least one wall that extends towards the turbine means. Λt least one wall may be in the form of a baffle. Preferably, the guidance means includes at least two walls5 that converge towards the turbine means. Accordingly, the guidance means may have (lie effect of corralling or concentrating the approaching water from a wide catchment corresponding to the mouth and forcing it through a narrow region corresponding to lhe throat.

Accordingly, (lie guidance means may be funnel-shaped. The guidance means may be0 in the form of a truncated cone or, alternatively, in the form of a truncated open pyramid, flic pyramid may have four walls, fn one embodiment of the invention, the seailυor (or equivalent natural feature of the relevant water body) may constitute the floor of the funnel.

The internal surface of the guidance means facing the approaching water may include ats least one wall that is convex and/or one wall that is planar. The throat section of the guidance means may extend at least partially over the turbine means. Accordingly, the throat may at least partially overlap the turbine means. The throat may terminate in region corresponding to the mid-point of the turbine means. An opposed, mirror image, second guidance means may combine with the first guidance means to form a 0 continuous corridor that is at its narrowest at their meeting point and diverges outward at each end remote from the turbine means. Alternatively, the throat may terminate close to, but not overlapping with, the volume defined by the sweep of the turbine means. In such case, a second opposed guidance means may be spaced from the llrsl guidance means, at least by the diameter of the turbine means. Although water cannot be significantly compressed, of course water can be pressurised. The effect of a large body of water entering a wide catchment defined by the guidance means and corralled through a narrow orifice, i.e. the throat, is to pressurise the water. As it passes through the throat in to a lower pressure region of water, the flowing water may be accelerated as it comes into the region of the turbine means. The guidance means may include adjustable bailies or walls whereby to vary the torque and/or rotational velocity of the turbine means. Depending on the available volume of water and speed <>r water (low, the guidance means may be adjustable to widen the mouth or entrance and/or narrow or expand the throat to capture a greater or lesser volume of water and/or to increase or reduce the pressurisation of the water as it approaches the throat. I ^"his may be advantageous where water flow is tidal and (he current speed varies periodically and predictably, llic plant may include a current flow sensor linked to computer means to control the adjustment of the guidance means.

The turbine means may include any suitable turbine arrangement whereby to convert the linear water flow into rotational motion of the turbine. The turbine means may include a plurality of spaced impellers or blades. llic impellers or blades may be evenly spaced. The impellers or blades may substantially radially extend from a turbine hub. The hub may be axially aligned with (he direction of water flow in the same manner as a jet turbine, or may be adapted to rotate about an axis transverse to the direction of water flow, lhc impellers or blades may be configured to be bi-directional, whereby they will effectively rotate in either direction, depending on the direction of the water flow. Where the blades arc bi-directional, typically the turbine means will be partially submerged, whereby only the lower half of the turbine means will be under water so that the blades arc free to move through the low resistance air above on the return passage. Alternatively, the turbine means may be movable as a discrete structure and may be reversible in direction, i.e. rotatable by 180 degrees about a vertical axis. For example, the turbine means may be mounted on a swivel table or ring to reverse the direction in which the impellers or blades are facing. Such an arrangement may be suitable for use where the plant is fully submerged and the turbine means is entirely surrounded by water. The face of each impeller or blade facing the approaching water llυw may be generally concave to maximise the drive imparted to the turbine by the water flow. Conversely, the opposite side of the impeller or blade may be convex to limit the water resistance to which the impellers or blades arc subjected on the return passage.

The plant may be partially submerged and buoyant to float at or near the surface of the water to allow the turbine means to be only partially submerged so that the plurality of impellers or blades are raised out of the water to permit return passage of the impellers or blades through air and driven passage of the impellers or blades through the water, llic plant may include one or more ballast containers that may be filled with water to lower the plant or pumped with air Lo raise the plant, for example, for maintenance and repair. The ballast container may form part of the plant structure. Optionally, at leas! one wall of at least one of lhe ballast containers is shared with at least one wall of the guidance means. Preferably, the plant includes four ballast containers formed in the recesses corresponding tυ lhe one or more narrow tliroat sections of the plant. Where the plant is fully submerged, the approaching water immediately preceding the turbine means may, by the effect of the guidance means, have enhanced speed and/or pressure relative to the water surrounding the upper region of the turbine means, whereby there is a significant differential in force applied by the water flow, relative to the water surrounding the upper region. Accordingly, preferably the guidance means directs the approaching water to the lower region of the turbine means, being forced rapidly through the narrow gap of the guidance means proximal to the guidance means.

The turbine means may include reverse means to accommodate the periodic change in the direction of the current of the water. The reverse means may include reversible gears to permit the access of rotational of the turbine means to remain stationary. The reverse means may include the pivoting of the blades about radial axes and against bias for either the driven or the return passage by the action of a guide or deflection rail to reduce the resistance of the blades through the return passage.

The plant may include second guidance means opposed to the guidance means on the opposite side of the turbine means whereby, on reversal of the direction of water How to a second direction, the second guidance means is effective to direct the water approaching the plant from the second direction towards the turbine means. In a particularly preferred embodiment, the first and second guidance means form opposed funnel structures, either co-terminal with respect to each other or located around the outer sweep of the turbine means, i.e. spaced relative to each other by, for example, the d iameter of the tu rbine means .

Ilic transmission means may include any suitable structure or technology for transmitting the rotational mechanical motion of the turbine means to power the electricity generator for conversion to electrical energy. Typically, although not exclusively, the transmission means may include a rotatable shaft co-operable with the turbine hub, whereby the shall in turn drives the electricity generator.

The electricity generator includes available technologies for performing such functions and will typically be connected to a mains electricity grid.

BRIHF DHSC⁷RIP I ]()N OF I HH DRAWINCIS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described wilh reference to the drawings are not to be construed as limiting on the scope of the invention. Tn the drawings:

Figure I is a scheinalic side view of a power generator according to a first embodiment of the invention;

Figure 2 is a front plan view of the first embodiment shown in Figure 1; Figure 3 is a top plan view of the first embodiment shown in Figure 1 ;

Figure 4 is a schematic side view of a second embodiment of the present invention; Figure 5 is a front plan view of the second embodiment shown in Figure 4;

Figure 6 is a schematic side view of a third embodiment of the present invention; Figure 7 is a rear plan view of the third embodiment shown in Figure 6; and Figure 8 is a front plan view of the third embodiment shown in Figure 6. DH I AILKD DHSCRIP I ION OF TFTR DRAWINGS Inter alia this invention relates to the production of electricity on a moderate to large scale using sea, ocean or river currents. An additional use of the present invention is as a water pumping station using river currents. Without limiting the foregoing, preferred embodiments of the invention will now be described with reference to electricity generators driven by tidal Hows. Typically tidal current ebb and flow on a 24.8 hour cycle including four phases, including two incoming tidal phases and two out going tidal phases. In an area with a significant head, being the differential in depth of water between peak low and high tides, there should be a sufficiently strong current for 20 hours of the 24.8 hour cycle. To some extent existing technology can be utilised, particularly with regard to the use of a standard turbine used for windmills and other mechanical, flu id -driven, power generating devices. Obvious modifications may be made for scaling against ingress of water in to component parts and the selection of corrosion/resistant component materials, particularly where the invention is to be employed in the marine environment. Tn installing a large tidal power plant of the type contemplated in the present invention, consideration should be made to the impact of the installation on the surrounding environment. For example, a power station built near land may result in a small water level rise and an increase in shore erosion, for example where the installation is built near a sandy beach. Turning to Figure 1 , there is shown a first embodiment, of the present invention in the form of a tidal power generator 10 including a Iloating platform 20, water Ωow guides 30, a turbine 40 and an electricity generator 50.

The floating platform 20 and water flow guides 30 may be comprised of concrete and/or 5 marine grade stainless steel construction or other materials resistant to corrosion in a marine environment. The platform 20 is substantially planer along its length, but has a slightly inclined, raised front ramp 21 defining a hollow structure. Conversely, the rear section of the platform 20 includes a rearward Iy extending bulbous section 22, ugain defining a hollow section. The front ramp 21 and rear bulbous section 22 define water io tight cavities for buoyancy of the entire structure 10. Intermediate the front ramp 21 and rear bulbous section 22 is a substantially planar section 23 having a non-slip surface for the safety, maintenance and/or repair crews.

Fixed to the underside of the platform 20 is a pair of diverging guide walls 31 having leading edges 32 that arc inclined downwardly and outwardly. Bridging the lower edge 15 33 of the guide walls 31 is a substantially triangular shaped floor 34, terminating at its truncated apex in an area corresponding to the mid-point of the turbine 40. Accordingly, the lower surface 24 of the platform 20, the leading edges 32 and the floor 34 combined to define an inlet mouth 35.

The walls 31 , floor 34 and lower surface 24 converge Io deflne a throat 36 through0 which water is forced under pressure directly to the turbine 40. The outlet on the other side of the throat 36 is open whereby water is forced to "squirt" through the throat 36. rapidly increasing in velocity as it exists the throat 36, whereby to engage downwardly depending turbine spikes or blades 41. The blades 41 form part of a plurality of circutnferentially evenly spaced members radially extending from a central hub 42. Λs5 (he water is collected from the wide mouth 35 and forced through the narrow throat 36, the blades 41 are forced to rotate in the clockwise direction 43 shown in Figure 1. As the horizontal plane of the platform 20 is aligned with the water surface, the blades 41 travel through a lower drive passage 44 through the water and an upper return passage 45 through air, the latter being a low resistance passage relative Io the drive passage 44.0 Λs the water travels past the generator 40, it flows past a rear fixed rudder 37 adapted to ensure that the generator structure 10 is aligned with the water flow. At tiic front of the platform 20, eyelets 25 arc provided to enable the sccurcmcnt of heavy ropes, chains or cables 26 attached to an anchor point 27 that is fixed to sea floor. Accordingly, the combined action of the rudder 37, the outer surface 38 of the walls 31 and the 5 sccurcmcnt of the chains 26 to the anchor point 27 causes the generator structure 10 to self-correct to always face the oncoming water flow, tor example, when the tidal power generator 10 is placed in a tidal water flow environment, the structure 10 will tend to orient itself whereby the rear rudder 37 will be pushed sideways so that the generator 10 pivots about the anchor point 27. The mouth 35 inevitably always faces the oncoming water flow, whether the tide is going in or out. Accordingly, lhe generator 10 tor its effective operation requires a clear circular area having a radius defined by the distance between Lhe anchoring point 27 and the rear most tip 28 of the platform 20.

Electricity generation is obtained by the driven rotation of the hub 42 which is operatively connected by bevelled gears to a rotating sha.fi 51 using standard mechanical gearing arrangements. Preferably, the rotating shaft 51 is enclosed lor safety reasons and to protect the machinery against environmental corrosive effects, lhe electricity generator 50 includes a stand alone cabin 52 that encloses an electricity generator using technology well known in lhe art. The electricity may be optionally stored in battery means in the cabin 52. However, preferably, generated electricity is delivered on shore via a heavy duty insulated cable 53 that may extend above water or below water according to security constraints and surrounding man-made and natural structures. Alternatively, on land, the cable 53 receiving installation may be equipped with a cable recoiling device to ensure that the cable 53 is kept taut irrespective of the location of the pole 54 attached to the cable 53 relative to the land receiving installation.

The turbine 40 includes a serni circular guard 46 to minimise the hazard of the rotating blades 41 posed to repair or maintenance crews.

The square-mouthed funnel of the first embodiment described with reference to generator 10 is but one configuration suitable to capture a flowing body of water and to concentrate and pressurise the water as it Hows towards a constricted throat 36 and may be rectangular, round, ovaJ, triangular or any other suitable shape. For the purposes of the present embodiments, the mouth 35 is described as substantially square and this corresponds to structures that are generally easily fabricated using planar, prefabricated sheets of concrete or metal.

Referring to Figures 4 and 5, there is shown a second embodiment in the form of a completely submerged generator 100 having an upper section 120 comprising ceiling water How guides 130, a floor 134, a turbine 140 and a cavity 150 adapted to house an electricity generator 155. Λ central passage 156 through the cavity 150 is defined by a sealed cover 146, so that the cavity 150 is scaled against ingress of water whilst permitting the return passage of the blades 141. Because the return passage of the blades 141 is also through water, minimisation of the resistance through the return passage is achieved by providing a concave surface 147 facing oncoming water flow that is concave whereby to retard as large a volume of water as possible, whereas the reverse leeward face 148 of the blade 141 is convex to minimise resistance through the return passage as best seen in Figure 5.

The water flow guides 130 include converging side walls 131 and a front ceiling 121 that combine with (he floor 134 Io form an open mouth 135 adapted to capture a large volume of water and to concentrate its pressure as it progresses towards the turbine 140.

The generator 100 is axially bi symmetrical whereby the opposite end 22 of the generator 100 is identical but opposed, in shape and configuration relative to the front end 121 a. Accordingly, this fixed installation 100 is aligned, at installation, with the tidal Hows. The orientation of the blades 141 are adapted to be reversed with each change in water How direction corresponding to in and out going tides and reverse gears arc provided on the hub 142 whereby to accommodate the reverse flow of water according to the tidal direction. Alternatively, rather than reversing the orientation of the blades 141, the hub 142 may be provided with two axially separated sections, each hub section supporting an independent set of blades, a first set adapted to operate with the incoming tide and the second set adapted to operate with the outgoing tide, the unused set being permitted to rotate freely, disengaged from the gearing connected to the electricity generator 155.

Turning to Figures 6, 7 and 8, there is shown a third embodiment in the form of a tidal power generator 200 that is axially bisymroctrical in a manner similar to that of the second embodiment shown in Figure 4. However, rather than having a substantially planar floor 134, the power generator 200 includes a raised and inclined lloor 234 that acts to increase the pressurisalion of the volume of water moving through the mouth 235. By corollary, providing a diverging outgoing mouth 222 facilitates a reduction in pressure on the leeward end of the generator 200, whereby the speed of the water that is pressurised as it approaches the throat 236 is accelerated as it travels through the narrowest section of the throat 236 and out through the outgoing mouth 222 to provide fast travelling water as the water engages the spikes 241. Otherwise, the third embodiment is similar to that described in relation to the second embodiment.

Through-out the specification and claims the word "comprise" and its derivatives is intended to have an inclusive rather than exclusive meaning unless the context requires otherwise.

Tt will be appreciated by those skilled in the art that many modiiϊealiυns and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.

Claims

The claims:

1. An electricity generation device to generate electricity from tidal flows of water, said device including:

power translation means at a centralised location, said power translation means displaceable by water flow to move a transmission means opcrably connected to a electricity generator; and

water flow guidance means having at least one wall made from substantially inflexible material and inclined towards said centralised location, and a ceiling generally aligned in non-parallel relationship to at least one wall of the water flow guidance means, said water ilow guidance means operable to corral the water approaching said device at an approach velocity towards said power translation means at said centralised location,

wherein the water immediately preceding said power translation means has increased velocity relative to the approach velocity and an increased water pressure relative to that of the approaching water.

2. The device according to claim I , wherein the power translation means includes turbine means adapted to translate the generally linear motion of trie flowing water into rotational motion.

3. The device according to claim 1. wherein said guidance means has at least one second wall substantially opposed to at least one of said su stantially inflcxihle walls, at least one of said substantially inflexible walls and at least one of said second opposed walls opposed to each other and converging towards said power translation means.

4. The device according to claim 1, wherein said guidance means is funnel shaped and the ceiling is continuous with the at least one substantially inflexible wall and the at least one non-parallel wall.

5. The device according to claim 1 , further including at least one ballast conlainer.

6. The device accordingly Io claim 5, wherein at least one wall of at least one said ballast container is shared with at least one wall of said guidance means.

7. llie device according to claim 1, further including a frame or platform on which or in which said electricity generator is located.

8. The device according to claim 7, wherein said device includes said platform and at 5 leait one wall of said guidance means forms part of said platform.

9. The device accordingly to claim 1 , wherein said guidance means includes a wide mouth remote Jϊom said power translation means and a narrow throat close to said power translation means.

10. The device according to claim 9, wherein said throat a( least partially overlaps io with said power translation means.

11. The device according to claim 2, wherein said guidance means is adjustable relative to said turbine means to vary the torque and/or rotational velocity of said turbine means.

12. The device according to claim 2, wherein said turbine means includes a turbine 15 having a plurality of evenly spaced impellers.

13. The device according to claim 12, wherein said device is partially submerged and buoyant to float at or near the surface of the water, whereby the upper region of said turbine having said plurality of impellers is raised out of the water to permit return passage of said impellers through air and driven passage of said impellers

20 through water.

14. The device according to claim 12, wherein said device is fully submerged whereby the return passage of the upper region of said turbine is through the water and driven passage of said impellers is also through water, said guidance means directing lhe approaching water to the lower region of said turbine means.

25 15. The device according to claim 1, wherein said power translation means includes reverse means to accommodate the periodic change in the direction of the current of the water.

16. The device according to claim 1, wherein ^aid guidance means is in the form of a truncated cone.

17. The device according to claim 1 , wherein said guidance means is in the form of a truncated open pyramid.

18. The device according to claim 1 , further including second guidance means opposed to said guidance means on the opposite side of said power translation means whereby, on reversal of the direction of water flow to a second direction, said second guidance means is effective to direct the water approaching said device from said second direction towards said power translation means.

19. The device according to claim 1 , further including a rudder on the opposite side of said power translation means to that of said guidance means to ensure that said device tends Io align with the water flow.