CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No. PCT/IE2018/000002 filed Mar. 7, 2018, claiming priority based on Irish Patent Application Nos. S2017/0052 filed Mar. 7, 2017 and S2017/0142 filed Jul. 12, 2017, the disclosures of all of which are incorporated herein by reference.

The present invention relates to an energy generating system and in particular, the invention relates to an energy generating system for generating energy from a sea tide. The invention also relates to a method for generating energy from a sea tide.

Sea tides rise and fall twice every twenty-five hours approximately. Depending on the location, the water level differential between high and low tide levels can be as high as twelve meters. Such tides comprise a significant amount of energy, and harnessing such energy would significantly reduce the dependency on other sources of energy, for example, the burning of fossil fuel, nuclear energy and the like.

There is therefore an need for an energy generating system for generating energy from a sea tide, and there is also a need for a method for generating energy from a sea tide.

The present invention is directed towards providing such an energy generating system and a method.

According to the invention there is provided an energy generating system for generating energy from a sea tide comprising a dam configured to isolate a water containment area from a sea, the dam comprising at least one variable height dam element, a buoyancy means co-operable with each dam element and configured to control the height of the corresponding dam element in response to a level of water, the dam element being configured to define a water race between the water containment area and the sea to allow water flow therethrough between the sea and the water containment area, a water wheel operably located in each water race configured to produce usable energy.

Preferably, each buoyancy means is configured to progressively rise the corresponding dam element in response to a rising tide. Advantageously, each buoyancy means is configured to progressively lower the corresponding dam element in response to a falling water level of the water in the water containment area.

In one aspect of the invention each buoyancy means extends transversely relative to the corresponding dam element on at least one side of the dam element. Preferably, each buoyancy means extends transversely relative to the corresponding dam element on respective opposite sides thereof.

In another aspect of the invention at least one main guide means is configured to guide each dam element in a generally upwardly and downwardly direction.

In another aspect of the invention a pair of spaced apart upstanding support members are provided extending upwardly from a sea bed for supporting each dam element therebetween, and a main sealing means is provided for forming a seal between each dam element and the corresponding upstanding support members. Preferably, each dam element and the corresponding buoyancy means are configured to move relative to the pair of upstanding support members.

Advantageously, the main guide means extend longitudinally along at least one of the upstanding support members.

In one aspect of the invention each upstanding support member defines a corresponding one of the main guide means of the corresponding upstanding support member as a corresponding elongated main guide slot.

Preferably, each dam element comprises one of a flexible membrane and a plurality of dam panels hingeadly connected in series. Advantageously, each dam element comprises the plurality of the hingeadly connected dam panels, the dam panels of each dam element being moveable in a concertina manner between an inoperative folded state with the dam panels lying side by side and parallel to each other and an operative state with the dam panels substantially aligned with each other to form the dam element. Ideally, a plurality of secondary sealing means are provided for forming seals between the respective dam panels when the corresponding dam element is in the operative state.

Preferably, each dam panel of each dam element comprises one of the secondary sealing means for sealing the dam panel to an adjacent one of the dam panels in the operative state.

In one aspect of the invention the dam panels of each dam element are configured to be progressively drawn from the folded state into the operative state in response to upward movement of the corresponding buoyancy means, and the dam panels are progressively returned from the operative state to the folded state in response to downward movement of the corresponding buoyancy means.

In another aspect of the invention the dam panels of each dam element are weighted to return to the folded state under gravity, in response to downward movement of the corresponding buoyancy means.

Preferably, the dam panels of each dam element are stored in the folded state in a corresponding chamber. Advantageously, the chamber of each dam element in which the dam panels thereof are stored in the folded state is located adjacent the sea bed. Preferably, the chamber of each dam element in which the dam panels thereof are stored in the folded state is recessed into the sea bed.

In another aspect of the invention an uppermost one of the dam panels of each dam element is sealably coupled to the corresponding buoyancy means. Preferably, the uppermost one of the dam panels of each dam element is adjustably coupled to the corresponding buoyancy means such that the spacing between the buoyancy means and the uppermost dam panel is variable.

Preferably, the dam panels of each dam element are moveable within the corresponding main guide means. Advantageously, the dam panels of each dam element are sealably and slideably engageable in the corresponding main guide means.

In one aspect of the invention a secondary guide means is provided for guiding each buoyancy means as the buoyancy means rises and falls in response to the rising and falling water levels.

In another aspect of the invention each buoyancy means defines with the corresponding dam element the corresponding water race.

In a further aspect of the invention each buoyancy means comprises a pair of spaced apart buoyancy tanks. Preferably, the buoyancy tanks of each pair thereof define with the corresponding dam element, the corresponding water race.

In another aspect of the invention each water wheel is configured to rotate in one direction in response to a rising tide, and to rotate in the opposite direction in response to a falling tide. Preferably, each water wheel comprises a plurality of circumferentially spaced apart water engaging elements located on the water wheel and configured to extend into the corresponding water race. Advantageously, the water engaging elements are equi-spaced apart circumferentially around the periphery of the corresponding water wheel.

In one aspect of the invention each water engaging element defines a hollow interior region. Preferably, the hollow interior region of each water engaging element is evacuated to a pressure below atmospheric pressure.

In another aspect of the invention each water engaging element is radially spaced apart outwardly from the periphery of the corresponding water wheel.

In another aspect of the invention each water wheel is supported on the corresponding buoyancy means.

Preferably, each water wheel is rotatably carried on the corresponding buoyancy means.

Advantageously, each water wheel is supported on the corresponding buoyancy means such that the water wheel is continuously operably located in the corresponding water race.

In another aspect of the invention each water wheel is rotatably carried on a support means mounted on the corresponding buoyancy means.

In a further aspect of the invention each water wheel is mounted fast on a drive shaft rotatably supported on the corresponding buoyancy means. Preferably, the drive shaft of each water wheel is coupled one of directly and indirectly to an electricity generator.

In a further aspect of the invention a plurality of water races are defined by a plurality of corresponding dam elements, and the drive shafts of the water wheels corresponding to the respective dam elements are coupled in series, and are in turn coupled to the electricity generator.

In another aspect of the invention each drive shaft is coupled to the adjacent drive shaft by a flexible coupling.

Preferably, each drive shaft is coupled to the adjacent drive shaft by a universal joint.

In another aspect of the invention the dam comprises a plurality of spaced apart upstanding support members and a plurality of the dam elements located between respective adjacent pairs of the upstanding support members.

Preferably, each upstanding support member comprises a pair of spaced apart stanchions defining the main guide slot therebetween. Advantageously, the main sealing means comprises a pair of elongated sealing members extending from the respective stanchions into the corresponding main guide slot for sealably and slideably engaging the corresponding dam element in the operative state adjacent one end thereof.

In one aspect of the invention the dam is configured to extend from land at one side of an estuary to land at an opposite side of the estuary to define the water containment area in the estuary between the land and the dam.

In another aspect of the invention a sluice means is provided for selectively permitting water to flow through the dam bypassing the one or more water races. Preferably, the sluice means is located in the dam.

In one aspect of the invention the sluice means comprises a sluice panel having at least one sluice opening extending therethrough, and a closure means operable between a closed state closing the at least one sluice opening and an open state permitting water to flow through the at least one sluice opening. Preferably, the sluice panel extends generally upwardly from the sea bed.

Preferably, the sluice panel is sealably secured to the sea bed and extends between an adjacent pair of the upstanding support members and is sealably secured thereto.

In another aspect of the invention an urging means is provided for urging the closure means between the open and the closed states.

Preferably, the sluice panel comprises a plurality of spaced apart sluice openings, and the closure means comprises a closure panel comprising a plurality of communicating openings extending therethrough, the closure panel being slideable between the open state with the communicating opening aligned with the respective sluice openings, and the closed state closing the sluice openings.

Advantageously, the sluice openings in the sluice panel are equi-spaced apart vertically from each other.

Preferably, the closure panel is slideable in a generally vertical direction.

Advantageously, a pair of sluiced panels are provided spaced apart from each other and substantially parallel to each other with the closure panel located therebetween.

In another aspect of the invention each sluice panel is located between an adjacent pair of the upstanding support members.

In a further aspect of the invention a water level differential monitoring means for monitoring the water level differential on respective opposite sides of the dam is provided, and the closure means is urged into the open state in response to the monitored water level differential exceeding a predefined water level differential value.

Preferably, the water level differential monitoring means comprises a pair of level sensors for determining the difference in the level of water on the respective opposite sides of the dam.

In one aspect of the invention the urging means is responsive to the monitored water level differential exceeding the predefined water level differential value for urging the closure means from the closed state to the open state.

The invention also provides a dam for the energy generating system according to the invention.

The invention also provides a method for generating energy from a sea tide, the method comprising providing a dam to form a water containment area separated from the sea by the dam, locating at least one variable height dam element in the dam, coupling the dam element to a buoyancy means for controlling the height of the dam element in response to a level of water, configuring the dam element to define a water race between the water containment area and the sea to allow water to flow therethrough between the sea and the water containment area, and locating a water wheel in the water race to rotate in response to water flowing through the water race to produce useable energy.

The advantages of the invention are many. By virtue of the fact that the dam according to the invention of the energy generating system also according to the invention is of variable height, the energy generating system is continuously operable to continuously generate energy throughout all phases of the rising, falling and turning of a sea tide. Furthermore, by virtue of the fact that the dam element of the dam is of variable height and varies in response to water level, the energy generated by the energy generating system remains substantially constant for all states of the sea tide.

A further advantage of the invention lies in the fact that the energy generating system is located in an estuary, which can be located in a relatively sheltered location whereby the estuary, and in turn the energy generating system is protected from stormy conditions out at sea.

A further advantage of the invention is achieved when the dam is provided with the sluice means which allows for the control of the water level differential between the water levels on respective opposite sides of the dam. By limiting the water level differential to a predefined safe water level differential value, any danger to the integrity of the dam, which could arise as a result of an excessive water level differential, is avoided.

A further advantage of the invention is that the energy generating system according to the invention is a non-polluting system. It neither pollutes the water, nor does it pollute the air. Additionally, by generating electricity from tidal movement, once the capital cost of the energy generating system has been recovered, the only other costs in operating the system are maintenance and running costs. The raw material, namely, the tidal movement of the sea water for generating the electricity, is cost free.

