FIELD OF THE INVENTION

The present invention relates to a water energy apparatus for extracting electrical power from the vertical movement of water and to a water energy assembly comprising one or more water energy apparatus.

BACKGROUND TO THE INVENTION

An increase in awareness of environmental issues and in knowledge of the types of available renewable energy sources has led to greater activity in the development of electricity generating devices from alternative sources to those such as oil, gas and nuclear.

Renewable energy is energy that comes from natural resources such as wind, sunlight, rain and tides; all of which are naturally occurring in the environment and replenish naturally. Use of such natural sources of energy can supplement and replace large amounts of existing sources of energy while achieving an overall reduction in CO2 emissions to meet the growing demands of worldwide legislation.

Hydroelectric dams are the most common form of renewable energy. However, they have a negative environmental impact in terms of blocking the river flow and their construction can also result in the displacement of large numbers of the local population.

The use of "run of river" hydro systems avoids these issues. These can be characterised as either high water head and low volumetric flow or characterised by low water head and high volumetric flow.

Low head hydro systems, such as Waterwheels and Archimedes screws are generally physically constrained to be installed in specific locations in the river, this restricts the number of sites these devices can be used in. It is desirable to provide an energy producing apparatus that directly converts the energy from vertical fluid flow, for example river flow or ocean waves, into rotary motion to generate power which avoids the above mentioned problems.

SUMMARY OF THE INVENTION

The first aspect of the invention concerns a water energy apparatus (1) for extracting electrical power from the vertical movement of water, the apparatus comprising a housing (5), a rotor assembly (6) within the housing (5) comprising a central rotor shaft (22) and a plurality of vane members (14) mounted radially around the central rotor shaft (22), a top horizontal plane gravitationally above the rotor assembly (6) and a bottom horizontal plane gravitationally below the rotor assembly (6), a water inlet (7) positioned in the top horizontal plane defining an opening in the housing (5), a water outlet (8) positioned in the bottom horizontal plane defining an opening in the housing (5), an air outlet (11) positioned in the housing (5) below the top horizontal plane and gravitationally above the central rotor shaft (22), an air inlet (13) positioned in the housing (5) above the bottom horizontal plane and gravitationally below the central rotor shaft (22), and wherein both the air outlet (11) and the air inlet (13) are positioned on the same side of the housing, a water sealing shroud (9) arranged between the water inlet (7) and the water outlet (8) and an air sealing shroud (10) arranged between the air outlet (11) and the air inlet (13) which seal the rotor assembly (6). In a further embodiment, an inlet reservoir (2) may be mounted on the housing (5) on the top horizontal plane and an outlet reservoir (4) may be mounted to the housing (5) on the bottom horizontal plane.

In embodiments, the air outlet (11) may be connected to an air outlet duct (21), the air inlet (13) may be connected to an air inlet duct (20). Both the air outlet duct (21) and the air inlet duct (20) may be connected to an air generator fan (12).

In embodiments, the vane members (14) are straight or cranked or curved.

The vane members (14) may be arranged evenly spaced around the circumference of the central rotor shaft (22) or helically along the longitudinal axis of the central rotor shaft (22).

The vane members (14) may comprise a flap valve (25).

In embodiments, the housing (5) may be a modular ISO shipping container.

The inlet reservoir (2) may be connected to a water inlet pipe (16).

The outlet reservoir (4) may be connected to a water outlet pipe (17). The vane members may comprise a radial seal and/or a longitudinal seal.

The water may be supplied to the water inlet (7), the inlet reservoir (2) and/or the water inlet pipe (16) from a dam or a run of river system. The water inlet (7), inlet reservoir (2) and/or water inlet pipe (16) may be supplied with water by a water pipework system.

In embodiments, an electrical generator (27) may be attached to the central rotor shaft (22). The second aspect of the present invention concerns a water energy assembly comprising two or more water energy apparatus (1).

In embodiments, the water energy apparatus (1) may be in series and may share the same central rotor shaft (22).

The water energy apparatus (1) may be stacked gravitationally vertically. A crossover housing (28) may connect the water outlet (8) of the gravitationally upper water energy apparatus (1) with the water inlet (7) of the gravitationally lower water energy apparatus (1)· In embodiments, the water energy apparatus (1) may be stacked in parallel and in opposite directions.

The water energy apparatus (1) may share one or more water inlet pipes (16) and/or one or more water outlet pipes (17). The water energy apparatus (1) may be stacked gravitationally vertically and horizontally, and the outlet reservoir (4) of the gravitationally upper water energy apparatus (1) may be connected to the inlet reservoir (2) of the gravitationally lower water energy apparatus (1) by piping.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of a cross-sectional view of the water energy apparatus according to an embodiment of the present invention; Figure 2 is a diagrammatic representation of a cross-sectional view of the water energy apparatus according to an embodiment of the present invention under no flow conditions;

Figure 3 is a diagrammatic representation of a cross-sectional view of the water energy apparatus under flowing condition; Figure 4 is a diagrammatic representation of the air ducting and fan system;

Figure 5 is an isometric view of the water energy apparatus with a partial cut away section to show the housing and rotor assembly;

Figure 6 is an isometric view of the rotor assembly and flap valve; Figure 7 is a diagrammatic representation of the rotor assembly showing the flap valve;

Figure 8 is a diagrammatic representation of a cross-sectional view of the cranked shaped segments; Figure 9 is a diagrammatical representation of the inlet reservoir, water energy apparatus and outlet reservoir;

Figure 10 is a diagrammatical representation of the attached inlet reservoir, water energy apparatus and outlet reservoir and the air energy system;

Figure 11 is a diagrammatical representation of the water energy assembly comprising vertically stacked water energy apparatus;

Figure 12 is a diagrammatical representation of the water energy assembly comprising water energy apparatus joined axially;

Figure 13 is a diagrammatical representation of the water energy assembly with the water energy apparatus joined in parallel; Figure 14 is a diagrammatical representation of the water energy assembly with the water energy apparatus joined by pipework in series;

Figure 15 is a diagrammatical representation of the water energy apparatus mounted in a wave energy application;

Figure 16 is a diagrammatical representation of the water energy apparatus mounted in a tidal lagoon application. DETAILED DESCRIPTION

It has been found that a water energy apparatus (1) for extracting electrical power from the vertical movement of water, the apparatus comprising a housing (5), a rotor assembly (6) within the housing (5) comprising a central rotor shaft (22) and a plurality of vane members (14) mounted radially around the central rotor shaft (22), a top horizontal plane gravitationally above the rotor assembly (6) and a bottom horizontal plane gravitationally below the rotor assembly (6), a water inlet (7) positioned in the top horizontal plane defining an opening in the housing (5), a water outlet (8) positioned in the bottom horizontal plane defining an opening in the housing (5), an air outlet (11) positioned in the housing (5) gravitationally below the top horizontal plane and gravitationally above the central rotor shaft (22), an air inlet (13) positioned in the housing (5) above the bottom horizontal plane and gravitationally below the central rotor shaft (22), and wherein both the air outlet (11) and the air inlet (13) are positioned on the same side of the housing (5), a water sealing shroud (9) arranged between the water inlet (7) and the water outlet (8) and an air sealing shroud (10) arranged between the air outlet (1 1) and the air inlet (13) which seal the rotor assembly (6), alleviates the previously mentioned problems.

The water energy apparatus of the present invention preferably works with a hydraulic head of 2.5 to 10 m, i.e. the gravitationally vertical distance from a water source such as a reservoir or a river to the outlet of the water energy apparatus and preferably with flow rates of up to 1000 m ³ /min. The water energy apparatus can be installed in a number of locations, in proximity to a river, run of river system, above a weir or behind a dam, downstream of a weir or dam, in combination with a wave energy device that provides the required water through the overtopping feature to a reservoir from where the water is fed to the water energy apparatus. Further, the water energy apparatus may be mounted in or at a tidal lagoon barrier wall. In a further embodiment, the water inlet, inlet reservoir and/or water inlet pipe can be supplied with water by a water pipework system having a sufficient hydraulic head of at least 2.5 m, such as for example utility clean water, wastewater or dam tailrace water. The modular design of the water energy apparatus allows for easy shipping worldwide. The housing of the water energy apparatus may be a modular ISO shipping container. ISO shipping containers share a number of key construction features to withstand the stresses of intermoda! shipping, to facilitate their handling and to allow stacking. ISO shipping containers can be transferred between rail, truck, and ship by container cranes at container terminals. Forklifts, reach stackers, straddle carriers, and cranes may be used to load and unload trucks or trains. Both unused and used or recycled containers can be used in accordance with the present invention.

The water energy apparatus further comprises a rotor assembly. The rotor assembly comprises a central rotor shaft and a plurality of vane members. The central rotor shaft extends gravitationally horizontal through the length of the housing and extending through the housing on one or at both ends of the housing. Electrical generators may be attached to any one or both ends of the central rotor shaft.

The plurality of vane members may be mounted radially around the central rotor shaft. The individua! vane members may be straight, cranked, or curved. Straight vane members extend from the central rotor shaft to the water and/or air sealing shroud in a straight line. Cranked vane members change direction at least once along their length while curved vane members gradually change the direction along their length. The length of a vane member is understood as the distance between the central rotor shaft up to the edge facing the sealing shroud. Cranked vane members or backward swept vane members help the air at the gravitational top and the water at the gravitational bottom of the rotor assembly to leave the rotor segments, thus avoiding negative torque on the rotor. Negative torque in the sense of the present invention is understood as the force directed against the rotation direction in use. The torque generated is dependent on the difference in the hydrostatic pressure acting on the vane member that is gravitationally at the top (top vane) and the one that is gravitationally at the bottom of the rotor (bottom vane) as shown in Figure 2. The hydrostatic pressure on the top vane causes a negative torque on the rotor while the hydrostatic pressure on the bottom vane causes (positive) torque on the rotor. As the rotor segments of the top vane will always be filled with a mixture of air and water, these rotor segments will have less hydrostatic loading,

A rotor segment as understood in the sense of the present invention is the space confined by the central rotor shaft, two adjacent vane members and the sealing shroud. During operation, the segments are filled with fluid, i.e. air and/or water. The rotor segments may be compartmentalised, such that there are more than one compartments between two adjacent vane members along the gravitationally horizontal length in the housing. Alternatively, there is only one compartment in a rotor segment.

The vane members may be radially evenly spaced around the central rotor shaft. Further, the vane members may be mounted in a straight line along the longitudinal axis of the central rotor shaft or be wound helically around the longitudinal axis of the central rotor shaft. The vane members may run along the full length of that part of the central rotor shaft that is located within the housing. Alternatively, the vane members may be shorter and either arranged side by side or in a stacked configuration without overlapping. The vane members may comprise a flap valve in order to avoid negative torque by increasing the rate of filling and discharging water from the rotor segments.

The vane member may further comprise a longitudinal and/or a radial seal. The radial seal is attached to the edge of the vane member that runs from the central rotor shaft to the air or water sealing shroud. The longitudinal seal is attached to the edge of the vane member that faces the air or water sealing shroud. These seals control the rate of water transfer across the vane members. These seals may be for example dynamic brush seals or rubber seals.

The rotor assembly may comprise any number of vane members depending on the size of the rotor assembly. For example, a rotor assembly having a 2.4 m diameter may have 8 vane members mounted radially around the central rotor shaft. The size of the housing defines a top horizontal plane gravitationally above the rotor assembly and a bottom horizontal plane gravitationally below the rotor assembly. The gravitational top and bottom of the housing coincide with these planes.

The water energy apparatus of the present invention further comprises a water inlet positioned in the top horizontal plane defining an opening in the housing. In the bottom horizontal plane a water outlet defines an opening in the housing.

The water energy apparatus further comprises an air inlet positioned in the housing above the bottom horizontal plane and gravitationally below the central rotor shaft, and an air outlet positioned in the housing below the top horizontal plane and gravitationally above the central rotor shaft. Both the air inlet and the air outlet are positioned on the same side of the housing.

The air outlet may be connected to an air outlet duct and the air inlet may be connected to an air inlet duct. Both the air inlet duct and the air outlet duct may be connected to an air generator fan. Near the top horizontal plane and the water inlet where the incoming water displaces air in the rotor segments a high pressure is created. Near the bottom horizontal plane and the water outlet a low pressure zone is created when the water flows out of the water outlet as the rotor segments have to be filled with air from the air inlet. The air generator fan may be used to produce electricity using the air flow from the air outlet to the air inlet thus increasing the efficiency of the power generation. The water energy apparatus further comprises a water sealing shroud and an air sealing shroud. These two sealing shrouds form a cylindrical enclosure for the rotor assembly and possess openings that coincide with the water inlet, water outlet, air outlet and air inlet. That part of this enclosure that curves around the rotor assembly from the water inlet to the water outlet and covers the rotor segments that transport the incoming water from the water inlet to the water outlet is the water sealing shroud. That part of this enclosure that covers the rotor segments which transport the air from the air inlet to the air outlet is the air sealing shroud. In operation, air is circulating from the air inlet into the rotor segments which transport the air up to the air outlet. The water streaming into the rotor segments through the water inlet pushes the air out of the rotor segment increasing the air pressure. The air leaves the area of the rotor assembly through the air outlet, travels through the air outlet duct and the air generator fan into the air inlet duct and then through the air inlet into the rotor segments to replace the water that is flowing out of the water outlet.

Both the air sealing shroud and the water sealing shroud do not prevent the rotor assembly from rotating when in operation but seal the rotor segments and thus prevent water from flowing through the rotor assembly outside of the rotor segments. The modular design of the water energy apparatus of the present invention allows for unprobiemaiic mounting of an inlet reservoir and/or outlet reservoir which also may be made from ISO shipping container, for example from half height containers. The use of half height containers as inlet and/or outlet reservoir increases the flexibility of the installation. The inlet reservoir may be mounted to the housing on the top horizontal plane. The outlet reservoir may be mounted to the housing on the bottom horizontal plane.

The inlet reservoir may be connected to a water inlet pipe. Use of a water inlet pipe allows for flexibility regarding the placing of the water energy apparatus. For example, the water energy apparatus may be placed on a floating barge, beside a river or at a distance from the water supply while the water inlet pipe ensures that water is taken at the appropriate location. The outlet reservoir may be connected to a water outlet pipe. The water outlet pipe ensures that after the water has flowed through the water energy apparatus it can be directed to a designated location thus allowing for a higher flexibility when placing the water energy apparatus.

In order to increase the energy efficiency, two or more water energy apparatus can be combined to form a water energy assembly. Several configurations are possible. Two or more water energy apparatus may be in series while sharing the same central rotor shaft and thus requiring only one electrical generator. However, in a further embodiment electrical generators may be attached at both ends of the central rotor shaft. Alternatively, the two or more water energy apparatus may be stacked gravitationally vertically, i.e. on top of each other. Preferably, the housing of the stacked water energy apparatus is an ISO shipping container for this purpose. Such an water energy assembly may comprise a crossover housing that connects the water outlet of the gravitationally upper water energy apparatus with the water inlet of the gravitationally lower water energy apparatus. Such a water energy assembly provides enhanced energy efficiency if a water supply with sufficient head is available.

Alternatively, the water energy assembly may comprise water energy apparatus that are stacked in parallel and in opposite directions. Preferably, the water energy apparatus share one or more water inlet pipes and/or one or more water outlet pipes. As a further alternative, the two or more water energy apparatus are gravitationally vertically and horizontally stacked. This assembly is particularly useful if the water energy assembly has to be positioned on a slope. Preferably the outlet reservoir of the gravitationally upper water energy apparatus may be connected to the inlet reservoir of the gravitationally lower water energy apparatus. Referring to figure 1 , the water energy apparatus 1 comprises an inlet reservoir 2 and a generator unit 3 and an outlet reservoir 4. The generator unit 3 comprises a housing 5 and a rotor assembly 6.

The housing 5 comprises a water inlet 7 and a water outlet 8, a water sealing shroud 9 and an air sealing shroud 10. The housing 5 also comprises an air outlet 1 1 , an air inlet 13 and a rotor assembly 6.

The rotor assembly 6 comprises of a plurality of vane members 14 mounted radially on the central rotor shaft 22. A rotor segment 15 is formed between adjacent vane members 14, the central rotor shaft 22 and the either a water sealing shroud 9 or an air sealing shroud 10..

Referring to figure 2, the water energy apparatus 1 is shown in the non flowing condition. The water fills the water inlet pipe 16, the inlet reservoir 2 and the rotor segments 15 before flowing out through the water outlet.

The rotor segments 15 on the water side of the rotor assembly 6 (located between the water inlet and the water outlet when viewed in the rotation direction of the rotor assembly) are filled with water. The rotor segments 15 on the air side of the rotor assembly 6 (located between the air inlet and the air outlet when viewed in in the rotation direction of the rotor assembly) are filled with air.

The hydrostatic water pressure, on the water side of the rotor assembly 6, acts on the vane member 14 at the top 18 of the rotor assembly 6 and on the vane member 14 at the bottom 19 of the rotor assembly 6 (shown as bold arrows in Figure 2). The hydrostatic pressure acting on the vane member 14 at the bottom 19 is higher than the hydrostatic pressure acting on the vane member 14 at the top 18, resulting in a clockwise torque on the rotor assembly 6.

The hydrostatic pressure on the top 18 vane member 14 causes an anticlockwise negative torque on the rotor assembly 6. The hydrostatic pressure on the bottom 19 vane member 14 causes a clockwise positive torque on the rotor assembly 6. The torque generated is dependent on the difference in the hydrostatic pressure acting on the top 18 vane member 14 and the bottom 19 vane member 14.

The difference in the nature of the fluid in the rotor segments 15 on the water and the air side of the rotor assembly 6 results in a clockwise torque reaction on the rotor assembly.

Referring to figure 3, the water energy apparatus 1 is shown in the flowing condition.

The rotor assembly 6 is shown in an embodiment in which the vane members 14 do not seal the rotor segments 15 at the top 18 and at the bottom 19 of the housing 5 when facing the water inlet. The water from the inlet pipe 16 and the inlet reservoir 2 flows into the rotor segment 15 at the top of the rotor assembly 6 through the water inlet 7.

The water from the rotor segment 15 at the bottom of the rotor assembly 6 flows into the outlet reservoir 4 and out through outlet pipe 17.

The water flows from the inlet reservoir 2, is transported by the rotor segments 15 and then into the outlet reservoir 4.

The rotor assembly 6 rotates clockwise within the housing 3, driven by the torque resulting from the water in the rotor segments 15 on the water side and the air in the rotor segments 15 on the air side of the rotor assembly 6.

Referring to figure 4, the water energy apparatus 1 is shown in the flowing condition.

The water from the inlet reservoir 2 flows into the rotor segment 15 at the top of the rotor assembly 6.

The water entering the rotor segment 15 forces the air to exit the rotor segment 15 through the air outlet 11 and into the air outlet duct 21 provided to enable the air to exit the housing. This enables the air to be removed from the rotor segment 15 which is then filled with water, before the rotor segment 15 moves into the water side. The dotted arrows visualise the path of air, the continuous arrows represent the flow of the water.

An air inlet duct 20 is provided to enable air to enter the housing 5 and then into the rotor segments 15.

The water from the rotor segment 15 at the bottom of the rotor assembly 6 flows into the outlet reservoir 4 and is replaced in the rotor segment 15 by air from the air inlet 13.

An air generator fan 12 is positioned in line between the air outlet duct 21 and the air inlet duct 20. The air flows from the rotor segment 15 at the top, through the air outlet 11 and air outlet duct 21 , through the air generator fan 12, through the air inlet duct 20 and air inlet 13 and then into the rotor segment 15 at the bottom of the rotor assembly 6.

The pressure differential across the air generator fan 12 and the flow of air causes the air generator fan 12 to rotate. This rotation is converted into usable electrical energy.

Referring to figure 5, an isometric cross sectional view of the water energy apparatus 1 is shown.

The inlet reservoir 2 is mounted on top of the generator unit 3 which is mounted on top of the outlet reservoir 4. The rotor assembly 6 is mounted within the housing 5.

The air outlet duct 21 , air generator fan 12 and the air inlet duct 20 are shown.

Referring to figure 6, an isometric view of a rotor assembly 6 is shown.

The rotor assembly 6 comprises a rotor central shaft 22 and a plurality of radially mounted vane members 14. A longitudinal seal 23 is provided on the outer edge of the vane member 14 where the vane member 14 faces the water sealing shroud 9 or air sealing shroud 10 in the rotor assembly 6.

A radial seal 24 is provided on both longitudinal ends of each vane member 14.

The longitudinal seal 23 and the radial seal 24 prevent fluid flow between the rotor assembly 6 and the water sealing shroud 9 and air sealing shroud 10.

A flap valve 25 is provided on each vane 14. The flap valve 25 is maintained closed and sealed on the vane 14 by spring force as long as there is no differential pressure across the vane member 14. The flap valve 25 is adapted to be opened by a differential pressure across the vane member 14.

The flap valves 25 enable fluids to flow between adjacent rotor segments 15. This increases the rate of fill or discharge of the rotor segments 15. Further, the presence of flap valves 25 increases the rotation speed of the rotor assembly 6 and thus the power produced.

Referring to figure 7, the water energy apparatus 1 is shown with the flap valves 25 in operation.

At the top of the rotor assembly 6, the water flows against the rotation of the rotor assembly 6 through the open flap valves 25 (continuous arrows). This increases the speed of filling the rotor segments 15 with water.

At the bottom of the rotor assembly 6, the air flows through the open flap valves 25 (dotted arrows). This increases the rate of filling the rotor segments 15 with air and the rate of discharge of the water from the rotor segment 15 into the outlet reservoir 4.

Referring to figure 8, the rotor assembly 6 is shown with cranked vane members 26. The cranked vane members 26 at the top of the rotor assembly 6 aid the discharge of the air from the rotor segment 15. Any air entrained in the rotor segment 15 on the water side of the rotor assembly 6 will result in an torque reaction in the opposite direction of the operating torque direction.

The cranked vane members 26 at the bottom of the rotor assembly 6 aid the discharge of the water from the rotor segment 15. Any water entrained in the rotor segment 15 on the air side of the rotor assembly 6 will result in a torque reaction in the opposite direction of the operating torque direction. The cranked vane members 26 improve the rate of discharge of the fluids from the rotor segments 15 and minimise the torque reactions in the opposite direction of the operating torque direction, which will improve performance.

In embodiments, the vane members 14 or cranked vane members 26 can be mounted axially on the central rotor shaft 22. Alternatively, the vane members 14 or the cranked members 26 or any other configuration of the vane members can be mounted helically onto the central rotor shaft 22 which will reduce vibration and noise while allowing the unit to run more smoothly.

Referring to figure 9, the water energy apparatus 1 is shown with a shipping container as the housing 5.

The generator unit 3 may be based on a 12 m ISO standard shipping container. An electrical generator 27 can be fitted at one, or both ends of the central rotor shaft 22.

The inlet reservoir 2 and the outlet reservoir 4 may be based on "half height" 12 m ISO Standard shipping containers. A plurality of water inlet pipes 16 and water outlet pipes 17 may be attached to the inlet reservoir 2 and outlet reservoir 4, respectively.

Referring to figure 10, the water energy apparatus 1 is shown with inlet reservoir 2, generator unit 3 and outlet reservoir 4 based on shipping containers which are joined together to form one unit. A plurality of air outlet ducts 21 , air generator fans 12 and air inlet ducts 20 can be attached along the longitudinal axis of the shipping containers on the water energy apparatus 1. In embodiments, the rotor assembly 6, inlet reservoir 2, and/or outlet reservoir 4 may be compartmentalised with each compartment having separate air outlet ducts, 21 , air generator fans 12, air inlet ducts 20, water inlet pipes 16 and/or water outlet pipes 17. Referring to figure 1 1 , a water energy assembly is shown comprising two water energy apparatus 1 which are mounted gravitationally vertically stacked in series.

A crossover housing 28 can be used to act as the outlet reservoir 4 of the gravitationally upper water energy apparatus 1 and as the inlet reservoir 2 of the gravitationally lower water energy apparatus 1.

Referring to figure 12, a water energy assembly is shown comprising two or more water energy apparatus 1 which are mounted axially and use a common central rotor shaft 22 and a common electrical generator 27.

Referring to figure 13, the water energy assembly is shown comprising two or more water energy apparatus 1 which are mounted in parallel and use common water inlet pipes 16 and water outlet pipes 17 for each compartment. The water energy apparatus 1 are arranged in opposite directions.

Referring to figure 14, the water energy assembly comprising water energy apparatus 1 can be gravitationally vertically and horizontally stacked and the outlet reservoir 4 of the gravitationally upper water energy apparatus 1 is connected to the inlet reservoir 2 of the gravitationally lower water energy apparatus 1 by piping. The water outlet pipes 17 of the gravitationally upper water energy apparatus 1 can be connected to the water inlet pipes 16 of the gravitationally lower water energy apparatus 1.

In this configuration, the water can be taken from a river or dam at a gravitationally upper area and then piped through water energy assembly, in gravitationally vertical steps, to be discharged back into the river at a gravitationally lower level. Such a water energy assembly can have multiple water energy apparatus stacked in this way to provide multiple steps before the water is released again into a river or other place.

Referring to figure 15, the water energy apparatus 1 is shown mounted within a wave energy device 29. The wave energy device 29 is moored to the seabed using a mooring and power line 30. The wave energy device 29 is free to weathervane around the mooring and power line 30 to suit the prevailing weather conditions.

The wave energy device 29 is fitted with a plurality of overtopping features 31 that force the passing waves to move gravitationally upwards into an elevated reservoir 32. The water from the elevated reservoir 32 can then be supplied to the water energy apparatus 1 via the inlet reservoir 2 to produce electricity.

Referring to figure 16, the water energy apparatus 1 is shown mounted in a tidal lagoon barrier wall 33.

The sea is located on one side of the tidal lagoon barrier wall 33. The sea changes in gravitational height from low tide 34 to high tide 35, and back again.

The lagoon water 36 is located on the other side of the tidal lagoon barrier wall 33. The lagoon water 36 can be filled and emptied by the water energy apparatus 1.

During high tide 35, water is supplied to the water energy apparatus 1 through a pipework arrangement 37. Exiting the water energy apparatus 1 through the outlet reservoir 4, the water is directed to the lagoon water 36 filling the lagoon.

When the lagoon is filled to a higher level (head) while the sea tide is low, the pipework arrangement 37 can be set to supply the lagoon water 36 to the inlet reservoir 2 of the water energy apparatus 1 , thus generating energy. The water is then discharged into the sea through the outlet reservoir 4. The tidal lagoon barrier wall 33, pipework arrangement 37 and water energy apparatus

1 can be configured to suit any number of sea tide conditions, such as low tide 34 and high tide 35, and lagoon conditions, i.e. filling level gravitationally above or below the current sea tide condition, to maximise the energy that can be developed from the water energy apparatus 1 throughout the tidal cycle. Although a variety of embodiments have been described herein, these are provided by way of example only, and many variations and modifications on such embodiments will be apparent to the skilled person and fall within the scope of the present invention, which is defined by the appended claims and their equivalents.