WO2019158893A1

WO2019158893A1 - Dam structure

Info

Publication number: WO2019158893A1
Application number: PCT/GB2018/051841
Authority: WO
Inventors: Stuart Frank MURPHY
Original assignee: Murphy Stuart Frank
Priority date: 2018-02-16
Filing date: 2018-06-29
Publication date: 2019-08-22
Also published as: GB2571115B; GB201802572D0; GB2571115A

Abstract

A dam structure for a tidal power system comprises:a dam operable to prevent flow of water between a seaward side of the dam and a landward side of the dam; a turbine assembly located in the dam, the turbine assembly comprising a first turbine, the first turbine comprising a first seaward inlet on the seaward side of the dam and a first landward outlet on the landward side of the dam; and a generator assembly comprising a first generator operable to draw power from the first turbine when water flows through the first turbine from the first seaward inlet tothe first landward outlet, wherein the generator assembly is located remotely from the turbine assembly.

Description

Dam Structure

The invention relates to a dam structure, a tidal energy system, and related methods.

Tidal energy systems offer the potential to generate electricity while avoiding disadvantages associated with using fossil fuels in generation. It is desirable to increase the efficiency of tidal energy systems by maximising the amount of water that flows through the turbines, and to avoid periods of time during which no electricity is being generated. Additionally, as tidal energy systems are often located in a coastal environment, it is desirable to avoid damage to components (for example, due to corrosion) and to make it easier for maintenance of components to be carried out.

According to a first aspect of the invention, there is provided a dam structure for a tidal power system, the dam structure comprising: a dam operable to prevent flow of water between a seaward side of the dam and a landward side of the dam; a turbine assembly located in the dam, the turbine assembly comprising a first turbine, the first turbine comprising a first seaward inlet on the seaward side of the dam and a first landward outlet on the landward side of the dam; and a generator assembly comprising a first generator operable to draw power from the first turbine when water flows through the first turbine from the first seaward inlet to the first landward outlet, wherein the generator assembly is located remotely from the turbine assembly. Having the generator assembly located remotely from the turbine assembly means that maintenance may be carried out on the generator assembly more easily. This is particularly advantageous in situations where the turbine assembly is located below an operational water level for the turbines, as the generator assembly can be accessed at a location above the water.

In one example, the turbine assembly comprises a first landward inlet on the landward side of the dam and a first seaward outlet on the seaward side of the dam, the first generator operable to draw power from the first turbine when water flows through the first turbine from the first landward inlet to the first seaward outlet. This means that the dam structure can be used to generate power as the tide comes in and as the tide goes out.

In one example, the first turbine comprises a first turbine axis which extends in an upward direction in use. In one example, the first turbine comprises a substantially vertical first turbine axis. In one example, the generator assembly is located above the turbine assembly. This further increases the accessibility of the generator assembly.

In one example, the turbine assembly comprises a second turbine, the second turbine comprising a second seaward inlet on the seaward side of the dam and a second landward outlet on the landward side of the dam; and the generator assembly comprising a second generator operable to draw power from the second turbine when water flows through the second turbine from the second seaward inlet to the second landward outlet, wherein the second turbine is above the first turbine. Having a plurality of turbines offset vertically means that as the water level rises above the level of the second turbine, power can be generated using both of the first turbine and the second turbine, increasing the power generated by the dam structure. Additionally, the difference in water level between the landward side and the seaward side can be controlled, as explained below.

In one example, the turbine assembly the second turbine comprises a second landward inlet on the landward side of the dam and a second seaward outlet on the seaward side of the dam, the second generator operable to draw power from the second turbine when water flows through the second turbine from the second landward inlet to second the seaward outlet. This means that both turbines of the the dam structure can be used to generate power as the tide comes in and as the tide goes out.

In one example, the second turbine comprises a substantially vertical second turbine axis, wherein the first turbine axis and the second turbine axis are offset from each other horizontally. Having the turbine axes offset horizontally means that the turbine axes can be retracted vertically, allowing the turbines to be maintained and/or replaced easily.

In one example, the second turbine comprises a substantially vertical second turbine axis, wherein the first turbine axis extends through the second turbine and the second turbine axis surrounds the first turbine axis. Having the second turbine axis surrounding the first turbine axis allows the first and second turbine axes to rotate independently of each other, whilst minimising the space occupied inside the dam.

In one example, the dam structure further comprises a plurality of sluice gates for selectively closing the inlets and outlets of the first and second turbines. The sluice gates provide a simple means for opening and closing the inlets and outlets, allowing the difference in water level between the landward side and the seaward side can be controlled, as explained below.

In one example, the generator assembly is located above a water retaining portion of the dam structure. This helps avoid the generators coming into contact with water, reducing the likelihood of damage to the generators.

According to a second aspect of the invention, there is provided a tidal energy system comprising: a first storage basin; a second storage basin located landward of the first storage basin; and a dam structure according to the aspect above, located between the first storage basin and the second storage basin, wherein the first storage basin is operable to: receive and store incoming tidal water; and to deliver water to the second storage basin through the turbine assembly so that power is generated by the generator assembly.

In one example, the tidal energy system is operable to selectively open and close the inlets and outlets of the first and second turbines to maintain a predetermined water level difference between the first storage basin and the second storage basin. Power, output of the turbines is relatively constant, independent of the difference in head between the first and second storage basins. Consequently, maintaining the predetermined water level difference between the storage basins allows power to be generated over a longer time period, allowing demand matching to be facilitated for the tidal energy system.

In one example, the tidal energy system is operable to: open the first seaward inlet and first landward outlet; and close the first seaward outlet, in response to a first water level in the first storage basin being above the first seaward inlet and a second water level in the second storage basin being below the first water level, so that water flows through the first seaward inlet, the first turbine, and the first landward outlet, and the first generator draws power from the first turbine axis. In one example, the tidal energy system is operable to: open the second seaward inlet and the second landward outlet; and close the second seaward outlet, in response to the first water level in the first storage basin being above the second seaward inlet and the second water level being below the first water level, so that water flows through the second seaward inlet, the second turbine, and the second seaward outlet, and the second generator draws power from the first turbine axis.

In one example, the second storage basin is operable to: store incoming water from the first storage basin; and deliver water to the first storage basin through the turbine assembly so that power is generated by the generator assembly, in response to the second water level being higher than the first water level.

In one example, the tidal energy system further comprises a third storage basin located landward of the second storage basin; and a second dam structure according to the aspect above, located between the second storage basin and the third storage basin, wherein the second storage basin is operable to: receive and store incoming water from the first basin; and to deliver water to the second storage basin through the turbine assembly of the second dam structure so that power is generated by the generator assembly of the second dam structure. In one example, the generator assembly is located above a maximum water level. This helps avoid the generators coming into contact with water, reducing the likelihood of damage to the generators.

In one example, the turbine assembly further comprises an underwater turbine located below the first turbine, the underwater turbine located below a minimum tide level. This is advantageous, as the underwater turbines can generate some power from even a small difference in water levels on the landward and seaward sides of the dam. This is in contrast to systems having their lowest turbines on or slightly above the minimum tide level.

According to a third aspect of the invention, there is provided a method of servicing a dam structure or a tidal energy system, the method comprising: accessing the generator assembly to service a generator of the generator assembly.

For a better understanding of the invention reference is made, by way of example only, to the accompanying figures, in which:

FIG. 1 shows a schematic plan view of a tidal energy system according to an example embodiment of the present invention;

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

FIG. 3 shows a side sectional view of a dam structure;

FIG. 4A and 4B show front views of the dam structure;

FIG. 5 shows a side sectional view of a second dam structure;

FIG. 6A to 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; and

FIG. 7A to 7D show schematic side sectional view of the dam structure by way of explanation of the operation of the dam structure;

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.

The tidal energy system 1 comprises a first storage basin 10, a second storage basin 20, and a third storage basin 30. The second storage basin 20 is located landward (i.e. further from the sea) than the first storage basin 10. The third storage basin 30 is located landward (i.e. further from the sea) than the second storage basin. The second storage basin 20 is located between the first storage basin 10 and the third storage basin 30. The boundaries between the sea S and the first storage basin 10, between the first storage basin 10 and the second storage basin 20 and between the second storage basin 20 and the third storage basin 30 are provided by first, second and third dam structures 11 , 12, 13 respectively.

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

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

The third storage basin 30 is in use operable to receive and store water from the second storage basin 20, and to deliver water to the second storage basin 20 during operation of the tidal energy system 1.

The second storage basin 20 is, as already indicated, operable to receive and store water from the first storage basin 10, to deliver water therefrom to the third storage basin 30, to receive and store water from the third storage basin 30, and to deliver water therefrom into the first storage basin 10 during operation of the tidal energy system 1.

Turbines are provided between the first storage basin 10 and the second storage basin 20. Furthermore, turbines are provided between the second storage basin 20 and the third storage basin 30. The turbines are arranged such that movement of water from one storage basin 10, 20, 30 to the next drives the turbines 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 second 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. 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. FIG. 3 shows side sectional views of the dam structure 100, which is used for the dam structures 1 1 , 12, 13 for the tidal energy system. The dam structure 100 comprises a dam 102 operable to prevent flow of water between a seaward side 104 of the dam and a landward side 106 of the dam 102. The dam structure 100 comprises a turbine assembly 108. The turbine assembly 108 comprises a first turbine 1 10a, a second turbine 1 10b, a third turbine 110c and a fourth turbine 110d . The second turbine 110b is located above the first turbine 110a. The third turbine 110c is located above the second turbine 110b. The fourth turbine 110d is located above the third turbine 110c. As such, the four turbines 110a-d provide a series of turbines at a range of heights, with the inlets and outlets (see below) of the turbines 110a-d also located at a range of heights.

The first turbine 110a comprises a substantially vertical first turbine axis 112a. The second turbine 110b comprises a substantially vertical second turbine axis 112b. The third turbine 110c comprises a substantially vertical third turbine axis 112c. The fourth turbine 110d comprises a substantially vertical fourth turbine axis 112d. Each of the turbine axes 112a-d extends upwardly in use. The turbine axes 112a-d are offset from each other in a horizontal direction, which is landward horizontal direction. The first turbine 1 10a comprises a first seaward inlet 114a on the seaward side 104, and a first landward outlet 116a on the landward side 106. The first turbine 110a further comprises a first landward inlet 118a on the landward side 106, and a first seaward outlet 120a on the seaward side 104. The first seaward inlet 114a is in fluid communication with the first landward inlet 118a. The first landward outlet 116a is in communication with the first seaward outlet 120a.

The second turbine 110b comprises a second seaward inlet 114b on the seaward side 104, and a second landward outlet 116b on the landward side 106. The second turbine 110b comprises a second landward inlet 118b on the landward side 106, and a second seaward outlet 120b on the seaward side 104. The second seaward inlet 114b is in fluid communication with the second landward inlet 118b. The second landward outlet 116b is in communication with the second seaward outlet 120b.

The second seaward inlet 114b is located above the first seaward inlet 114a. The second landward outlet 116b is located above the first landward outlet 116a. The second landward inlet 118b is located above the first landward inlet 118a. The second seaward outlet 120b is located above the first seaward outlet 120a. The second seaward outlet 120b is adjacent to the first seaward inlet 114a. The second landward outlet 116b is adjacent to the first landward inlet 118a.

Similarly, the third and fourth turbines 110c, 110d each comprise respective seaward inlets, landward outlets, landward inlets and seaward outlets (reference numerals are omitted from FIG. 3 for clarity). As shown in FIG. 3, the respective inlets and outlets of the third turbine 110c are located above the respective inlets and outlets of the first and second turbines 110a, 110b. The respective inlets and outlets of the fourth turbine 110d are located above the respective inlets and outlets of the first, second and third turbines 110a, 110b, 110c. The turbine assembly 108 further comprises an underwater turbine 121. The underwater turbine 121 comprises a substantially horizontal turbine axis. The underwater turbine 121 is located below a minimum water level, such that it is always under water during the tide cycle. The underwater turbine 121 comprises a seaward opening 123 and a landward opening 125. The underwater turbine 121 is a unit which includes turbine blades and an internal generator (not shown) in a single unit. In other embodiments, a generator associated with the under turbine 121 is located in the generator assembly 122.

The dam structure comprises a generator assembly 122. The generator assembly 122 comprises a first generator 124a, a second generator 124b, a third generator 124c and a fourth generator 124d. The first generator 124a is coupled to the first turbine axis 112a. The second generator 124b is coupled to the second turbine axis 112b. The third generator 124c is coupled to the third turbine axis 112c. The fourth generator 124d is coupled to the fourth turbine axis 112d. The generator assembly 122 is located remotely from the turbine assembly 108. Each of the turbine axes 112a-d extends upwardly from its respective turbine 110a-d to its respective generator 124a-d. The generator assembly 122 is located above the turbine assembly 108. More specifically, the entirety of the generator assembly 122 is located above the turbine assembly 108. The generator assembly 122 is located above a water retaining portion of the dam 102. The generator assembly 122 is located above a maximum water level in use. The generator assembly 122 is located directly beneath an access road (not shown) located on top of the dam structure 100. These features increase the accessibility of the generator assembly 122 for maintenance and/or replacement of the generators 124a-d.

FIG. 4A shows a front view of the dam structure 100. For clarity, many of the reference numerals are omitted from FIG. 4A. FIG. 4A demonstrates how the dam structure comprises a plurality of turbine and generator assemblies 108, 122.

The underwater turbine 121 comprises a seaward sluice gate 126 and a landward sluice gate (not shown). The seaward sluice gate 126 is located in the seaward opening 123. The landward sluice gate is located in the landward opening 125. The landward sluice gate comprises all of the features of the seaward sluice gate 126 and operates in the same manner as the seaward sluice gate 126.

The seaward sluice gate 126 comprises a series of panels 128. The panels 128 are rotatably fixed to the seaward opening 123. The panels 128 are rotatable between a first position, in which the seaward sluice gate 126 is fully open, and a second position, in which the seaward sluice gate 126 is fully closed, as shown in FIG. 4A. This allows flow to be controlled through the underwater turbine 121.

FIG. 4B shows a front view of the dam structure 100. For clarity, many of the reference numerals are omitted from FIG. 4B.

Each of the inlets and outlets of the turbines 110a-d comprises a sluice gate. Each sluice gate is rotatable between a first position, in which the sluice gate is open (as shown in the left image of FIG. 4B), and a second a position, in which the sluice gate is closed (as shown in the right image of FIG. 4C. This allows flow to be controlled independently through each of the inlets and outlets of the turbines 110a-d. Additionally, the direction of flow through the turbines 110a-d (i.e. whether the flow is in a landward or seaward direction), can be controlled, as described below.

FIG. 5 shows a second dam structure 200. The second dam structure 200 comprises many of the same features as the dam structure 100, and only the differences are described here, with like reference numerals being used for like features. For example, the second dam structure 200 comprises the seaward inlets, landward outlets, landward inlets and seaward outlets as the dam structure 100. However, in the second dam structure 200, the turbine axes 212a-d of the four turbines 210a-d are not offset vertically and are coaxial.

The first turbine axis 212a passes through the second turbine 210b. The second turbine axis 212b surrounds the first turbine axis 212a.

The first turbine axis 212a and the second turbine axis 212b pass through the third turbine 210b. The third turbine axis 212c surrounds the second turbine axis 212b.

The first turbine axis 212a, the second turbine axis 212b and the third turbine axis 212c pass through the fourth turbine 210b. The fourth turbine axis 212d surrounds the third turbine axis 212c.

Each of the first to fourth turbines 210a-d can rotate independently of each other and provide drive to a second generator assembly 222 by a suitably arranged mechanical connection.

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 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.

The method of operation comprises the incoming phase including the steps of:

(a) receiving incoming tidal water in the first storage basin;

(b) delivering water from the first storage basin to the second storage basin; and

(c) delivering water from the second storage basin to the third storage basin.

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 turbines there-between, and wherein the turbines are opened depending on the relative 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.

The method still further comprises an outgoing phase including: (d) delivering water from the third storage basin to the second storage basin;

(e) delivering water from the second storage basin to the first storage basin; and

(f) delivering water from the first storage basin out of the system.

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 opened depending on the relative 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.

The method further comprises an intermediate phase between the incoming phase and the outgoing phase, the intermediate phase including:

(g) delivering water from the second storage basin to the first and third storage basins.

During the intermediate phase movement of water from one storage basin to the next is arranged to drive the turbines there-between, and wherein the turbines are opened depending on the 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.

FIG. 7 A shows a schematic side sectional view of the second dam structure 200 during operation in an incoming phase (as described below). At the point of the cycle of FIG. 7A, a seaward water level on the seaward side 104 is above the first seaward inlet 1 14a. A landward water level on the landward side 106 is below the seaward water level.

At this point, the first seaward inlet 114a and the first landward outlet 116a are open. The first seaward outlet 120a is closed. This means that water flows through the first seaward inlet 114a, the first turbine 210a, and the first landward outlet 116a, and a second generator assembly (corresponding to 222 of the embodiment of Figure 5) draws power from the first turbine 210a.

Additionally, the seaward sluice gate 126 and the landward sluice gate of the underwater turbine 121 are open. This means that water flows through the seaward sluice gate 126, the underwater turbine 121 and the landward sluice gate, with the internal generator of the underwater turbine 121 generating power.

FIG. 7B shows a schematic side sectional view of the second dam structure 200 during operation in the incoming phase (as described below). The point of the cycle of FIG. 7B is later than that of FIG. 7A, and, consequently, the seaward water level is higher in FIG. 7B. The seaward water level is above the second seaward inlet 114b. The landward water level is below the seaward water level.

At this point, the second seaward inlet 114b and the second landward outlet 116b are open. The second seaward outlet 120b is closed. This means that water flows through the second seaward inlet 114b, the second turbine 210b, and the second landward outlet 116b, and the second generator assembly draws power from the second turbine 210b.

Additionally, as in FIG. 7A, the first seaward inlet 114a and the first landward outlet 116a are open. The first seaward outlet 120a is closed. This means that water flows through the first seaward inlet 114a, the first turbine 210a, and the first landward outlet, and the second generator assembly draws power from the first turbine 210a.

FIG. 7C shows a schematic side sectional view of the second dam structure 200 during operation in the incoming phase (as described below). The point of the cycle of FIG. 7C is later than that of FIG. 7B, and, consequently, the seaward water level is higher in FIG. 7C. The seaward water level is above the third seaward inlet 114c. The landward water level is below the seaward water level.

At this point, the third seaward inlet 114c and the third landward outlet 116c are open. The third seaward outlet 120c is closed. This means that water flows through the third seaward inlet 1 14c, the third turbine 210c, and the third landward outlet 116c, and the second generator assembly draws power from the third turbine 210c.

Additionally, as in FIG. 7B the second seaward inlet 114b and the second landward outlet 116b are open. The second seaward outlet 120b is closed. This means that water flows through the second seaward inlet 114b, the second turbine 210b, and the second landward outlet, and the second generator assembly draws power from the second turbine 210b.

The first seaward inlet 114a and the first landward outlet 116a are open. The first seaward outlet 120a is closed. This means that water flows through the first seaward inlet 114a, the first turbine 210a, and the first landward outlet, and the second generator assembly draws power from the first turbine 210a. The seaward sluice gate 126 and the landward sluice gate of the underwater turbine 121 are open. This means that water flows through the seaward sluice gate 126, the underwater turbine 121 and the landward sluice gate, with the internal generator of the underwater turbine 121 generating power.

FIG. 7D shows a schematic side sectional view of the second dam structure 100 during operation in the incoming phase (as described below). The point of the cycle of FIG. 7D is later than that of FIG. 7C, and, consequently, the seaward water level is higher in FIG. 7D. The seaward water level is above the fourth seaward inlet 114d. The landward water level is below the seaward water level.

At this point, the fourth seaward inlet 114d and the fourth landward outlet 116d are open. The fourth seaward outlet 120d is closed. This means that water flows through the fourth seaward inlet 114d, the fourth turbine 210d, and the fourth landward outlet 116d, and the second generator assembly draws power from the fourth turbine 21 Od.

Additionally, as in FIG. 7C the third seaward inlet 114c and the third landward outlet 116c are open. The third seaward outlet 120c is closed. This means that water flows through the third seaward inlet 114c, the third turbine 210c, and the third landward outlet 116c, and the second generator assembly draws power from the third turbine 210c.

The second seaward inlet 114b and the second landward outlet 116b are open. The second seaward outlet 120b is closed. This means that water flows through the second seaward inlet 1 14b, the second turbine 210b, and the second landward outlet, and the second generator assembly draws power from the second turbine 210b.

The first seaward inlet 114a and the first landward outlet 116a are open. The first seaward outlet 120a is closed. This means that water flows through the first seaward inlet 114a, the first turbine 210a, and the first landward outlet, and the second generator assembly draws power from the first turbine 210a.

The seaward sluice gate 126 and the landward sluice gate of the underwater turbine 121 are open. This means that water flows through the seaward sluice gate 126, the underwater turbine 121 and the landward sluice gate, with the internal generator of the underwater turbine 121 generating power. Opening the gates in this way allows the difference in water levels between the seaward and landward sides to be maintained, which means that power can be generated over a longer time period, allowing demand matching to be facilitated for the tidal energy system.

Additionally, it will be appreciated that during the outgoing phase the second dam structure 200 operates in reverse, with the first generator 124a drawing power from the first turbine 210a when water flows through the first turbine 21 Oa from the first landward inlet 1 18a to first the seaward outlet 120a, and the second generator 124b drawing power from the second turbine 210b when water flows through the second turbine 210b from the second landward inlet 1 18b to second the landward outlet 120b.

It will be appreciated that the dam structure 100 operates in a similar manner to the second dam structure 200.

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.

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.

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.

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.

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.

Claims

1 . A dam structure for a tidal power system, the dam structure comprising:

a dam operable to prevent flow of water between a seaward side of the dam and a landward side of the dam;

a turbine assembly located in the dam, the turbine assembly comprising a first turbine, the first turbine comprising a first seaward inlet on the seaward side of the dam and a first landward outlet on the landward side of the dam; and

a generator assembly comprising a first generator operable to draw power from the first turbine when water flows through the first turbine from the first seaward inlet to the first landward outlet,

wherein the generator assembly is located remotely from the turbine assembly.

2. A dam structure according to claim 1 , wherein the turbine assembly comprises a first landward inlet on the landward side of the dam and a first seaward outlet on the seaward side of the dam, the first generator operable to draw power from the first turbine when water flows through the first turbine from the first landward inlet to the first seaward outlet.

3. A dam structure according to any preceding claim, wherein the first turbine comprises a substantially vertical first turbine axis.

4. A dam structure according to any preceding claim, wherein the turbine assembly comprises a second turbine, the second turbine comprising a second seaward inlet on the seaward side of the dam and a second landward outlet on the landward side of the dam; and the generator assembly comprising a second generator operable to draw power from the second turbine when water flows through the second turbine from the second seaward inlet to the second landward outlet,

wherein the second turbine is above the first turbine.

5. A dam structure according to claim 4, wherein the second turbine comprises a second landward inlet on the landward side of the dam and a second seaward outlet on the seaward side of the dam, the second generator operable to draw power from the second turbine when water flows through the second turbine from the second landward inlet to second the seaward outlet.

6. A dam structure according to claim 4 or 5, wherein the second turbine comprises a substantially vertical second turbine axis, wherein the first turbine axis and the second turbine axis are offset from each other horizontally.

7. A dam structure according to claim 4 or 5, wherein the second turbine comprises a substantially vertical second turbine axis, wherein the first turbine axis extends through the second turbine and the second turbine axis surrounds the first turbine axis.

8. A dam structure according to any of claims 4 to 7, further comprising a plurality of sluice gates for selectively closing the inlets and outlets of the first and second turbines.

9. A dam structure according to any previous claim, wherein the generator assembly is located above the turbine assembly.

10. A dam structure according to claim 9, wherein the generator assembly is located above a water retaining portion of the dam structure.

11. A tidal energy system comprising:

a first storage basin;

a second storage basin located landward of the first storage basin; and

a dam structure according to any preceding claim located between the first storage basin and the second storage basin,

wherein the first storage basin is operable to:

receive and store incoming tidal water; and

to deliver water to the second storage basin through the turbine assembly so that power is generated by the generator assembly.

12. A tidal energy system according to claim 10, wherein the dam structure is according to claim 4 or any claim dependent on claim 4, and the tidal energy system is operable to selectively open and close the inlets and outlets of the first and second turbines to maintain a predetermined water level difference between the first storage basin and the second storage basin.

13. A tidal energy system according to claim 11 , wherein the tidal energy system is operable to:

open the first seaward inlet and first landward outlet; and

close the first seaward outlet,

in response to a first water level in the first storage basin being above the first seaward inlet and a second water level in the second storage basin being below the first water level, so that water flows through the first seaward inlet, the first turbine, and the first landward outlet, and the first generator draws power from the first turbine axis.

14. A tidal energy system according to any of claims 7 to 12, wherein the generator assembly is located above a maximum water level.

15. A tidal energy system according to claim 13, wherein the turbine assembly further comprises an underwater turbine located below the first turbine, the underwater turbine located below a minimum tide level.

16. A method of servicing a dam structure according to any of claims 1 to 10 or a tidal energy system according to any of claims 11 to 15, the method comprising:

accessing the generator assembly to service a generator of the generator assembly.