GB2539638A

GB2539638A - Tidal Energy system

Info

Publication number: GB2539638A
Application number: GB1508509.5A
Authority: GB
Inventors: Frank Murphy Stuart
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-05-18
Filing date: 2015-05-18
Publication date: 2016-12-28
Anticipated expiration: 2035-05-18
Also published as: GB2539638B; GB201508509D0; WO2016185210A1

Abstract

A tidal energy system comprises three storage basins (reservoirs, lagoons) 10, 20, 30 connected in series via turbines. The seaward basin is connected to the sea via turbines. The basins fill and empty in response to tidal changes, thereby generating electricity. The use of three basins allows a lag between tidal changes and energy production, to smooth the power output. There may be additional reserve basins 101, 201, 301 connected to the main basins. The turbines may be eccentrically mounted in rotary mounts so that rotation of the mount changes the level of the turbine (figures 4 and 5).

Description

Tidal Energy System

FIELD

[1] The present invention relates to tidal energy systems, and to related methods. BACKGROUND [2] Tidal energy systems offer the potential to generate electricity while avoiding disadvantages associated with using fossil fuels in generation. In order to increase the efficiency of tidal energy systems it is desirable to maximise the amount of water that flows through the turbines, so for systems that employ tidal storage a location that that has a large tidal range is preferred. Use of a single basin for tidal storage leads to significant periods of time during which electricity is not being generated. These periods are typically while the tide is incoming and water is being accumulated in the basin, and while waiting for the outgoing tide to cause a reduction in water level outside the basin.

[3] Furthermore, in systems that use the head of accumulated water in a storage basin to drive turbines it may be difficult to ensure that the turbines are working at high efficiency as the basin empties and the head of accumulated water drops.

[4] Example embodiments aim to address issues associated with the prior art, whether identified herein or otherwise.

SUMMARY

[5] In one example embodiment there is provided a tidal energy system comprising: a seaward storage basin; a landward storage basin; and an intermediate storage basin between the seaward and landward storage basins; wherein: the seaward storage basin is in use operable: to receive and store incoming tidal water; to deliver water therefrom to the intermediate storage basin; to receive and store outgoing tidal water from the intermediate storage basin; and to deliver water therefrom out of the system; the landward storage basin is in use operable to: receive and store water from the intermediate storage basin; and to deliver water therefrom to the intermediate storage basin; and the intermediate storage basin is in use operable: to receive and store water from the seaward storage basin; to deliver water therefrom to the landward storage basin; to receive and store water from the landward storage basin; and to deliver water therefrom into the seaward storage basin. Suitably, a turbine is provided between the seaward storage basin and the intermediate storage basin and a turbine is provided between the intermediate storage basin and the landward storage basin, the turbines arranged such that movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are mounted for movement relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.

[6] In one example embodiment a turbine is provided between the sea and the seaward storage basin, said turbine arranged such that movement of water into the system from the sea, or movement of water out of the system from the seaward storage basin is arranged to drive said turbine, and wherein said turbine is mounted for movement relative to the water levels in the sea and the seaward storage basin to in use maintain a predetermined water level difference between input and output sides thereof as water moves into or out of the seaward storage basin.

[7] In one example embodiment one or more of the storage basins is provided with an associated reserve basin, arranged so that water may in use move between the basin and its reserve basin and from a reserve basin to the storage basin with which it is associated.

[8] In one example embodiment a turbine is provided between a storage basin and its reserve basin, and wherein said turbine is arranged such that movement of water into the reserve basin from the storage basin with which it is associated, or movement of water from the reserve basin into the associated basin is arranged to drive said turbine, and wherein said turbine is mounted for movement relative to the water levels in the basin and the associated reserve basin to in use maintain a predetermined water level difference between input and output sides thereof as water moves into the reserve basin from the associated storage basin or out of the reserve basin into the associated storage basin.

[9] In one example embodiment the tidal energy system further comprises a forward lagoon arranged seaward of the seaward storage basin and wherein the forward lagoon is arranged to shelter the seaward storage basin from the sea by pontoons, a solid or permeable breakwater or the like while still allowing tidal flow to and from the seaward storage basin.

[10] In one example embodiment one or more of said turbines is provided as a turbine assembly comprising an inlet/outlet on each side, operable so that in use movement of water through the turbine assembly in either direction drives the turbine.

[11] In one example embodiment one of more of said turbines is provided as a turbine assembly including a rotary mount, wherein rotation of the rotary mount changes the level of the turbine.

[12] In one example embodiment one or more of said turbines is provided as a turbine assembly comprising sluice gates operable to in use control movement of water there-through.

[13] In one example embodiment wherein one or more of said turbines is provided in a turbine assembly comprising two inlets on each side, wherein said inlets are mounted to move together in use according to the water level difference between input and output sides of the turbine assembly.

[14] In one example embodiment said inlets are mounted such that movement of one in an upward direction is accompanied by movement of the other in a downward direction.

[15] In one example embodiment there is provided a method of tidal energy generation using the tidal energy system of any preceding claim, the method comprising an incoming phase including: (a) receiving incoming tidal water in the seaward storage basin; (b) delivering water from the seaward storage basin to the intermediate storage basin; and (c) delivering water from the intermediate storage basin to the landward storage basin; wherein during the energy storage phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next; and comprising an outgoing phase including: (d) delivering water from the landward storage basin to the intermediate storage basin, (e) delivering water from the intermediate storage basin to the seaward storage basin; and (f) delivering water from the seaward storage basin out of the system; wherein during the energy delivery phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next; and characterised by further comprising an intermediate phase between the incoming phase and the outgoing phase, the intermediate phase including: (g) delivering water from the intermediate storage basin to the seaward and landward storage basins; wherein during the intermediate phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.

[16] According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

BRIEF DESCRIPTION OF DRAWINGS

[17] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: [18] FIG. 1 shows a schematic plan view of a tidal energy system according to an example embodiment of the present invention; [19] FIG. 2 shows a schematic side sectional view of the tidal energy system of FIG. 1, the section being along the centreline; [20] FIG. 3A-3D show schematic front views of a turbine assembly for use in the tidal energy system of FIG.1; [21] FIG. 4A-4G show a schematic side sectional views of the turbine assembly of FIG. 3A-3D; [22] FIG. 5A-5D show schematic front views of a turbine assembly for use in the tidal energy system of FIG.1 by way of explanation of the operation of the tidal energy system during a tidal cycle; [23] FIG. 6A-6M shows schematic side sectional views of the tidal energy system of FIG. 1 by way of explanation of the operation of the tidal energy system during a tidal cycle; and [24] FIG. 7 shows a graphical representation of operation of the turbines of the tidal energy system of FIG. 1 during a tidal cycle.

DESCRIPTION OF EMBODIMENTS

[25] FIG. 1 shows a schematic plan view of a tidal energy system 1 according to an example embodiment of the present invention. The tidal energy system 1 is for generating electrical energy from the tidal movement of sea water. Water is allowed to flow from the sea S into storage basins 10, 20, 30, which are also referred to as lagoons, as the tide rises, and allowed to flow from the tidal energy system 1 once the tide has gone out. Movement of water into and out of some of the storage basins 10, 20, 30, is used to drive turbines that are coupled to electrical generators, as described in detail further below.

[26] The tidal energy system 1 comprises a seaward storage basin 10, a landward storage basin 30, and an intermediate storage basin 20. The intermediate storage basin 20 is located between the seaward storage basin 10 and the landward storage basin 30. The boundaries between the sea S and the seaward storage basin 10, between the seaward storage basin 10 and the intermediate storage basin 20 and between the intermediate storage basin 20 and the landward storage basin 30 are provided by first, second and third dams 11, 12, 13 respectively.

[27] FIG. 2 shows a schematic side sectional view of the tidal energy system 1, the section being along the centreline.

[28] During an incoming tide the seaward storage basin 10 receives and stores incoming tidal water 10. Water from the seaward storage basin 10 may be delivered to the intermediate storage basin 20, and likewise the seaward storage basin 10 may receive and store outgoing tidal water from the intermediate storage basin 20 during operation of the tidal energy system 1. In addition, the seaward storage basin 10 may deliver water therefrom and out of the tidal energy system 1 to sea S during an outgoing tide.

[29] The landward storage basin 30 is in use operable to receive and store water from the intermediate storage basin 20, and to deliver water to the intermediate storage basin 20 during operation of the tidal energy system 1.

[30] The intermediate storage basin 20 is, as already indicated, operable to receive and store water from the seaward storage basin 10, to deliver water therefrom to the landward storage basin 30, to receive and store water from the landward storage basin 30, and to deliver water therefrom into the seaward storage basin 10 during operation of the tidal energy system 1.

[31] Turbines are provided between the seaward storage basin 10 and the intermediate storage basin 20. Furthermore, turbines are provided between the intermediate storage basin 20 and the landward storage basin 30. The turbines are arranged such that movement of water from one storage basin 10, 20, 30 to the next drives the turbine between the respective storage basins 10, 20, 30. By regulating movement of water within the system, the turbines that sit at the boundaries of the intermediate storage basin 20 can used to generate electricity during both incoming and outgoing tides, increasing the flexibility to match the output of the tidal energy system 1 to demand.

[32] It will be appreciated that in order for the system to drain completely under gravity, the seaward storage basin may be provided with an outflow that is lower than that of the intermediate storage basin, and in turn the intermediate storage basin may be provided with an outflow that is lower than that of the landward storage basin, However, this need not necessarily be achieved by a general downward slope from landward to seaward, as there may be drainage flues, pumps, or cambered or other surface features provided at the bottom of the storage basins. Furthermore, although a generally linear arrangement from seaward to landward is preferred in order that the bulk flows water may move in the system may take place also in a generally linear manner, it is to be understood that other geometries may be used, and "seaward" and "landward" ought to be interpreted herein in relation to their functions in receiving and delivering water. Similar considerations apply to the reserve storage basins, described in more detail below.

[33] The turbines are mounted for movement relative to the water levels in the storage basins 10, 20, 30 to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin 10, 20, 30 to the next. In this way demand matching is facilitated because the output of the turbines when operational is relatively constant, independent of the particular head of water in a single storage basin.

[34] The advantages of the arrangement of turbines at the boundaries of the intermediate storage basin 20 are built upon in the tidal energy system 1 by providing turbines between the sea S and the seaward storage basin 10. The turbines at the boundary between the sea S and the seaward storage basin 10 are arranged such that movement of water into the tidal energy system 1 from the sea S, or movement of water out of the tidal energy system 1 from the seaward storage basin 10 is arranged to drive said turbines. The turbines at the boundary between the sea S and the seaward storage basin 10 are mounted for movement relative to the water levels in the sea S and the seaward storage basin 10 to in use maintain a predetermined water level difference between input and output sides thereof as water moves into or out of the seaward storage basin 10.

[35] In the tidal energy system 1 each of the storage basins 10, 20, 30 is provided with associated reserve basins 101, 201 and 301 respectively. The reserve basin 101 for the seaward storage basin 10 is arranged so that water may in use move between the seaward storage basin 10 and the reserve basin 101 for the seaward storage basin 10, and in the reverse direction. Similarly, the reserve basin 201 for the intermediate storage basin 20 is arranged so that water may in use move between the intermediate storage basin 20 and the reserve basin 201 for the intermediate storage basin 20, and in the reverse direction. Again similarly, the reserve basin 301 for the landward storage basin 30 is arranged so that water may in use move between the landward storage basin 30 and the reserve basin 301 for the landward storage basin 30, and in the reverse direction. The reserve basins 101, 201, 301 as shown in the tidal energy system of Figure 1 are provided in two parts, one on either side of the associated storage basin, but this is not essential to their operation as described below. However, the two part reserve basins 101, 201, 301 provide a degree of symmetry for the tidal energy system 1 and increase the flexibility and potentially an increased rate of movement of water.

[36] Further turbines are provided between each of the storage basins 10, 20, 30 and its respective reserve basin 101, 201, 301, at dams 11', 12', 13'. These turbines are arranged such that movement of water into the reserve basin 101, 201, 301 from the storage basin 10, 20, 30 with which it is associated, or movement of water from the reserve basin 101, 201, 301 into the associated storage basin 10, 20, 30 is arranged to drive said turbines. As described in relation to the turbines between the storage basins 10, 20, 30, the turbines for the reserve basins 101, 201, 301 are mounted for movement relative to the water levels in the storage basin and the associated reserve basin to in use maintain a predetermined water level difference between input and output sides thereof as water moves into the reserve basin from the associated storage basin or out of the reserve basin into the associated storage basin.

[37] Further turbines are also provided between adjacent reserve lagoons, again as described in relation to the turbines between the storage basins 10, 20, 30.

[38] In the tidal energy system 1 a forward lagoon 40 is provided. The forward lagoon 40 is arranged seaward of the seaward storage basin 10 and serves to shelter the seaward storage basin 10. A permeable breakwater 41 and pontoons 42 provide protection from storms etc. while still allowing tidal flow to and from the seaward storage basin 11. Similar provisions are made for the reserve basins 101 to provide corresponding lagoons 40' by use of a permeable breakwater 41' and pontoons 42'.

[39] The turbines as described herein are provided in a turbine assembly comprising an inlet/outlet on each side, and are operable so that in use movement of water through the turbine assembly in either direction drives the turbine. Furthermore the turbine assemblies include a rotary mount, wherein rotation of the rotary mount changes the level of the turbine. The turbine assemblies further comprise sluice gates operable to open and close to thereby control movement of water through the turbines.

[40] FIG. 3A-3D show schematic front views of a turbine assembly 50 and FIG. 4A-4G show a schematic side sectional view of the turbine assembly 50. FIG. 3A-3D and FIG. 4A-4G show the turbine assembly 50 in different configurations according to the operational configuration of the tidal energy system 1 as will now be described.

[41] The turbine assembly 50 comprises first, second and third turbines 51, 52, 53. Each turbine 51, 52, 53 has individually operable sluice gates that open to allow water to flow through inlets to the turbine or to close to interrupt the flow of water through the inlets turbine. By rotating the turbine assembly 50 the vertical position of the inlets to the first and third turbines 51, 53 can be altered according to the water level in the basins at either side of the turbines.

[42] The inlets are mounted such that movement of the first turbine 51 in an upward direction is accompanied by movement of the third turbine 53 in a downward direction.

[43] FIG. 3A-3D show how the sluice gates can be controlled in accordance with the rotational position of the turbines, which as indicated is itself in use dependent on the relative water levels between the inlet and outlets for the turbines. The wall of the dam 11 shown in the drawings is provided with sluice gates that allow drainage there-through. The sluice gates are shown as V-shaped notches, which may be covered or uncovered as appropriate.

[44] FIG. 4A-4G show the turbine assembly 50 in different configurations according to the operational configuration of the tidal energy system 1 during a complete tidal cycle. It will be appreciated that the angle of the turbine within the turbine assembly, or other characteristics thereof, can be adjusted according to the direction of operation.

[45] FIG. 6A-6M show schematic side sectional views of the tidal energy system of FIG. 1 by way of explanation of the operation of the tidal energy system during a tidal cycle. In these views the movement of water between storage basins, and the accompanying generation of electrical energy is indicated symbolically. It is also shown in these views, where appropriate, that water may be moved between storage basins using sluice gates to drain, or to/from reserve storage basins to drain/top-up the storage basins, and that pumping or drainage of water out of the system may be provided for.

[46] The method of operation comprises an incoming phase including the steps of: (a) receiving incoming tidal water in the seaward storage basin; (b) delivering water from the seaward storage basin to the intermediate storage basin; and (c) delivering water from the intermediate storage basin to the landward storage basin.

[47] The method further comprises an energy storage phase during which movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.

[48] The method still further comprises an outgoing phase including: (d) delivering water from the landward storage basin to the intermediate storage basin; (e) delivering water from the intermediate storage basin to the seaward storage basin; and (f) delivering water from the seaward storage basin out of the system.

[49] During the energy delivery phase, movement of water from one storage basin to the next is arranged to drive the turbine there-between, and the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.

[50] The method further comprises an intermediate phase between the incoming phase and the outgoing phase, the intermediate phase including: (g) delivering water from the intermediate storage basin to the seaward and landward storage basins; [51] During the intermediate phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.

[52] As is illustrated in FIG. 7, operation of the turbines of the tidal energy system of FIG. 1 during a tidal cycle can smooth the electrical output of the system over time. The left graph shows the tide level over time, superimposed over blocks of time during which turbines in the first dam 11 are operational. These blocks are extended in size, to cover the hashed additional areas in embodiments that use wave valves or other techniques to increase the amount of water captured in the seaward storage basin so that the level is greater than provided by the high fide. The right graph shows the fide level overtime, superimposed over blocks of time during which turbines in the third dam 13 and second dam 12 are operational. These blocks alternate between the third dam turbines at hours 0-1, the second dam turbines at hours 2-4 and so on in sequence. Forced or other drainage from the intermediate storage basin is shown in the second and fourth operation blocks for the second dam.

[53] The methods and apparatus described herein may increase efficiency in tidal energy systems and thus enhance the environmental and other benefits associated with generation of electrical energy by capturing energy from tidal sources.

[54] Although a few preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

[55] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[56] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[57] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[58] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Key to Drawings The Multi-Level/Multi-Dam Power System "Power to Change the World" FIG. 1 Ensuring full efficiency The Multi-Dam System is an effective solution to harness tidal power but to truly maximise its efficiency we need to ensure that inclement conditions don't comprise its energy collection.

To this end, a Forward Lagoon will regulate water into the Multi-dam system so that stormy waters don't surge out of control. This means that every litre of water which travels through the system will generate energy.

The Forward Lagoon The Forward Lagoon is designed to improve the stability of the water entering the Turbines in Dam 1 and gain extra height in the mean level of sea water in the Forward Lagoon.

Storm swells that 50 foot waves would swamp Dam 1 and if the swell had a difference of just a few metres then the turbines would not have the maximum amount of water flowing through them. Therefore a large sea wall needs to be constructed to enclose Dam 1 and depending on each location built of sufficient height to prevent all or most storm surges spilling in to the Forward Lagoon at all times.

Looking at the oscillation of the waves it is apparent that we can gather the top half of the wave into a "Forward Lagoon" and use the extra height in water to generate more power and for longer cycles.

FIG. 2 How does it operate? In simple terms the 3 main lagoons are fed by sea water through 2m Turbines that on the rising water side allows the water to be controlled so there is a constant 2m difference in height from the input of sea water to the output of sea water creating a hydro-power flow through the turbines at all times and the same applies during each ebbing tide too.

Because the flow is effectively "restricted" by the 2m diameter turbine units-lagoon l's capacity and therefore level can be controlled by the number of "active" turbines in Dam A-some 450 turbines which will mitigate any variations in tidal pressure to maintain the 2m difference until high tide is reached in cycle 1.

FIGS 3A-3D Each wheel can be turned to line up with the single 2m turbine in the most efficient position to generate most energy.

FIG. 4 During the cycle of power generation from the sea into lagoon No. 1 the sluice gates of all the turbines in Dam 1 and Dam 2 are closed until sufficient water in Lagoon 1 can mirror the process above which will be approx. one hour behind Dam 1 or 2m of water height. Once Dam 2 has 2m of water covering the turbines then the sluice gates will open and generation of power from the turbines can begin. Again, control of both sets of Turbine sluice gates On Dam 1 and 2) will be needed to maintain the 2m flow over the operating turbines.

FIG. 4A Side elevation -incoming tide The wheel orientates the turbine at its lowest position. The sluice gate is opened at the optimum time to generate most energy.

FIG. 4B Side elevation -medium tide The wheel remains just below the tide level, as indicated here at medium tide.

FIG. 4C Side elevation -high tide At high tide the wheel is at its highest position allowing as much water to enter the Lagoon as possible.

FIG. 4D Side elevation -high tide 2 Once equilibrium has been established, the turbine will stop generating energy until the tide begins to ebb. Sluice gates close.

FIG. 4E Side elevation -high tide 2 The angle of the turbine re-orientates to efficiently produce energy with the ebbing tide.

FIG. 4F Side elevation -ebbing tide The ebbing tide draws the water from the Lagoon energising the turbines once more.

FIG. 4G Side elevation -low tide At low tide the turbine is in its bottom position as the Lagoon empties. The process is repeated.

FIG. 5A Dam 1 Each pod on Dam 1 will comprise 3 turbines as illustrated below. As the tide approaches each pod will orientate itself to maximise the flow through he turbines in order to create maximum energy. When the pod has rotated 90 degrees, all 3 turbines will be operational at peak power.

Image 1 -Sluice gates are closed. No generation of energy.

Image 2-The lowest sluice gate is opened once the tide is above the height of turbine.

Image 3 -Wheel turns to keep turbine at optimum height, just below the tide level.

Image 4 -When the wheel has turned 90 degrees, all turbines can be activated for peak power.

Image 6-At high tide the turbine will be at the 12 o'clock position on the wheel.

FIG. 5B This will allow Lagoon 1 to fill quickly, which in turn will allow the turbines in Dam 2 and Dam 3 to start generating energy as soon as possible.

During the ebbing tide, it will be optional to open the sluice gates to allow all 3 turbines to be operational (see Figure 20). This is to allow flexibility within the system to react to tidal conditions. For example, it may be preferential to keep more water within the system to allow Dams 2 and 3 to be generating power over a longer period.

Image 1 -Sluice gates are closed until the moment that the tide level reaches the bottom or the turbine.

Image 2-Once tide has ebbed to the bottom of the turbine, the sluice gates are opened.

Image 3 -Wheel ensures the turbine is kept just below the water height in the Lagoon.

Image 4 -Peak power is optional on the ebbing tide depending on the levels in Dams 2 and 3.

Image 6-At low tide the wheel is at the 6 o'clock position.

Image 7 -Sluice gates are closed. The sequence begins again.

FIG. 5C Dams 2 and 3 The Pods in Dams 2 and 3 will have two turbines and will operate with the same theory as those in Dam 1.

The turbines in Dam 2 will operate about one hour or 2m of water behind Dam 1, thus maintaining turbine power. The turbines in Dam 3 will be a further hour behind.

Image 1 -Sluice gates are closed. No generation of energy.

Image 4 -When the wheel has turned 90 degrees, both turbines can be activated for peak power.

FIG. 5D The sluice gates in Dam 1 and 2 will be left open but producing no power until high tide has happened and then closed to maintain the full tide height in Lagoon 1 and potentially Lagoon 2 subject to tidal pressures and the size of each individual plant.

At or about high tide it might be necessary to use reserve water to build up Lagoon 2 so power from Dam 3's turbines can be maintained until the sea level has dropped 2m and the turbines in Dam 1 can be fully opened. Then, the reverse cycle discharges water through all 3 Dams in a controlled manner to maintain the 2m height difference on all Dams and operating turbines.

Image 4 -Peak power is optional on the ebbing fide depending on the levels in the other Dams.

Image 6-At low fide the wheel is at the 6 o'clock position.

Image 7 -Sluice gates are closed. The sequence begins again.

FIG 6A Waste water flue opened in both Lagoons 2 and 3 to deep reserve Lagoon pools and/or pumped out to sea.

FIG. 6J Lagoon 3 topped up to tidal level by Reserve Lagoon.

FIG. 61\11 Waste water flue opened in both Lagoons 2 and 3 to deep reserve lagoon pools and/or pumped out to sea FIG. 7 The Turbines can achieve peak power midway through each cycle (see darkened areas) when each Turbine in each pod is operational. To moderate flow between Dams sluice gates can be closed

Claims

CLAIMS1. A tidal energy system comprising: a seaward storage basin; a landward storage basin; and an intermediate storage basin between the seaward and landward storage basins; wherein: the seaward storage basin is in use operable: to receive and store incoming tidal water; to deliver water therefrom to the intermediate storage basin; to receive and store outgoing tidal water from the intermediate storage basin; and to deliver water therefrom out of the system; the landward storage basin is in use operable to: receive and store water from the intermediate storage basin; and to deliver water therefrom to the intermediate storage basin; and the intermediate storage basin is in use operable: to receive and store water from the seaward storage basin; to deliver water therefrom to the landward storage basin; to receive and store water from the landward storage basin; and to deliver water therefrom into the seaward storage basin; wherein a turbine is provided between the seaward storage basin and the intermediate storage basin and a turbine is provided between the intermediate storage basin and the landward storage basin, the turbines arranged such that movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are mounted for movement relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.
2. The tidal energy system of claim 1, wherein a turbine is provided between the sea and the seaward storage basin, said turbine arranged such that movement of water into the system from the sea, or movement of water out of the system from the seaward storage basin is arranged to drive said turbine, and wherein said turbine is mounted for movement relative to the water levels in the sea and the seaward storage basin to in use maintain a predetermined water level difference between input and output sides thereof as water moves into or out of the seaward storage basin.
3. The tidal energy system of claim 1 or 2, wherein one or more of the storage basins is provided with an associated reserve basin, arranged so that water may in use move between the basin and its reserve basin and from a reserve basin to the storage basin with which it is associated.
4. The tidal energy system of claim 3, wherein a turbine is provided between a storage basin and its reserve basin, and wherein said turbine is arranged such that movement of water into the reserve basin from the storage basin with which it is associated, or movement of water from the reserve basin into the associated basin is arranged to drive said turbine, and wherein said turbine is mounted for movement relative to the water levels in the basin and the associated reserve basin to in use maintain a predetermined water level difference between input and output sides thereof as water moves into the reserve basin from the associated storage basin or out of the reserve basin into the associated storage basin.
5. The tidal energy system of any preceding claim, further comprising a forward lagoon arranged seaward of the seaward storage basin and wherein the forward lagoon is arranged to shelter the seaward storage basin from the sea by pontoons, a solid or permeable breakwater or the like while still allowing tidal flow to and from the seaward storage basin.
6. The tidal energy system of any preceding claim, wherein one or more of said turbines is provided as a turbine assembly comprising an inlet/outlet on each side, operable so that in use movement of water through the turbine assembly in either direction drives the turbine.
7. The tidal energy system of any preceding claim, wherein one of more of said turbines is provided as a turbine assembly including a rotary mount, wherein rotation of the rotary mount changes the level of the turbine.
8. The tidal energy system of any preceding claim, wherein one or more of said turbines is provided as a turbine assembly comprising sluice gates operable to in use control movement of water there-through.
9. The tidal energy system of any preceding claim, wherein one or more of said turbines is provided in a turbine assembly comprising two inlets on each side, wherein said inlets are mounted to move together in use according to the water level difference between input and output sides of the turbine assembly.
10. The tidal energy system of claim 9, wherein said inlets are mounted such that movement of one in an upward direction is accompanied by movement of the other in a downward direction.
11. A method of tidal energy generation using the tidal energy system of any preceding claim, the method comprising an incoming phase including: (a) receiving incoming tidal water in the seaward storage basin; (b) delivering water from the seaward storage basin to the intermediate storage basin; and (c) delivering water from the intermediate storage basin to the landward storage basin; wherein during the energy storage phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next; and comprising an outgoing phase including: (d) delivering water from the landward storage basin to the intermediate storage basin; (e) delivering water from the intermediate storage basin to the seaward storage basin; and (0 delivering water from the seaward storage basin out of the system; wherein during the energy delivery phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next; and characterised by further comprising an intermediate phase between the incoming phase and the outgoing phase, the intermediate phase including: (g) delivering water from the intermediate storage basin to the seaward and landward storage basins; wherein during the intermediate phase movement of water from one storage basin to the next is arranged to drive the turbine there-between, and wherein the turbines are moved relative to the water levels in the storage basins to in use maintain a predetermined water level difference between input and output sides thereof as water moves from one storage basin to the next.
12. A tidal energy system or a method substantially as described herein, with reference to the accompanying drawings.