GB2596173A

GB2596173A - Energy Harnessing System And Method Of Use Thereof

Info

Publication number: GB2596173A
Application number: GB2101558.1A
Authority: GB
Inventors: Knight Jeremy
Original assignee: Energy Storage Ltd
Current assignee: Energy Storage Ltd
Priority date: 2020-06-17
Filing date: 2021-02-04
Publication date: 2021-12-22
Also published as: GB2596097A8; GB2596097A; GB202009242D0; GB202101558D0

Abstract

A tidal energy generation system 10 comprises a support element 14 suitable for installation in a body of tidal water 12, a buoyant element 16 which is vertically translatable with respect to the support element 14, and a locking means 20. An electricity generator 36a generates electricity from the vertical movement. The buoyant element 16 can be locked relative to the support element 14 by locking means 20, to maintain the buoyant element 16 in its raised or lowered condition while the tidal water falls or rises respectively. The buoyant element 16 is then released to fall under gravity or rise due to buoyancy respectively, thereby driving the electricity generator 36a. At least one growth promotor associated with the buoyant element configured to promote the growth of a marine organism thereon. At least one element of the system forms an artificial tidal habitat; and a growth promotor is associated with the artificial tidal habitat to promote the growth of a marine organism thereon. The growth promoter may comprise coating which increases surface roughness, and/or a nutrient source or fertilization system.

Description

Energy Harnessing System And Method Of Use Thereof The present invention relates to an energy harnessing system for generating electricity from a body of tidal water. The present invention also relates to a method of use of such an energy harnessing system.

Renewable energy systems, such as wind turbines or solar panels, are increasingly viable alternatives to systems relying on fossil fuels for the generation and supply of electricity to an electricity grid.

The electricity grid has a frequency which must remain constant, despite fluctuations in the demand for electricity. If the grid is oversupplied or undersupplied with electricity relative to the demand, the frequency changes, which can result in damage to equipment and/or blackouts. However, the supply of electricity provided by some renewable energy systems is unpredictable and does not match demand at any one time. Any excess electricity produced by renewable energy systems must be discarded to avoid oversupplying the grid whilst any deficit must be compensated for by other means. This renewable energy harnessing system is both predictable and selectable.

One source of renewable energy is a body of tidal water. Twice a lunar day, a surface of the body of tidal water undergoes a cycle of rising to a high level before falling to a low level. This cycle is referred to as a tide. The highest level reached by the surface of the body of tidal water is called high tide, whilst the lowest level is called low tide. The height difference between high tide and low tide is referred to as a tidal range. Associated with the rise and fall of the surface are tidal currents or flows of the body of tidal water.

Tidal energy is conventionally understood to refer to energy extracted from a said tidal current and converted into electricity by an underwater tidal turbine. The flow velocity of the tidal current, and consequently the supply of electricity generated by the underwater tidal turbine, is greatest between low fide and high tide whilst being or being substantially zero at high fide and low tide. The generation of electricity from the tide is therefore predictable but a mismatch between demand and supply of electricity remains. Corrosion, erosion, marine growth and silting of the underwater turbine are further issues encountered with tidal energy.

The present invention seeks to provide a solution to these problems.

According to a first aspect of the present invention, there is provided an energy harnessing system for generating electricity from a body of tidal water, the energy harnessing system comprising: a support element suitable for installation in a body of tidal water; a buoyant element which is vertically translatable with respect to the support element in two opposing directions, the buoyant element having a buoyancy which enables flotation at or adjacent to a surface of the said body of tidal water and which forms an artificial tidal habitat; at least one growth promotor associated with the buoyant element configured to promote the growth of a marine organism thereon; an electricity generator for generating electricity from the vertical translation of the buoyant element; and a locking means for locking a vertical position of the buoyant element relative to the support element, so that, when the body of tidal water is in a tide-raised condition, the buoyant element is lockable by the locking means and then releasable to fall under gravity thereby driving the electricity generator once the surface of the body of water has lowered relative to the buoyant element, and when the body of tidal water is in a fide-lowered condition, the buoyant element is lockable by the locking means and then releasable to rise due to said buoyancy thereby driving the electricity generator once the surface of the body of water has risen relative to the buoyant element.

The provision of a growth promotor in association with the buoyant element of a tidal energy harnessing system allows for the system to be used in an agricultural context, via farming of marine plant or animal lift. The system can form an artificial habitat and ecosystem for marine life, which may improve the health of the water in which it is installed. The plant or animal matter could then be farmed, for example, as a mussel farm, which can be used for food.

Energy may be extracted from the vertical movements of the surface of the body of tidal water and converted into electricity. Energy may also be stored as either potential energy and/or buoyancy energy to improve and/or smooth out the supply of electricity to the grid. The energy harnessing system provides an environmentally friendly, offshore electricity generation and energy storing system. By storing energy mechanically, the energy harnessing system suffers minimal loss in energy-storing capability over time, particularly compared to alternative energy storage systems, such as chemical batteries. By comprising a buoyant element which may float at, on, beneath to the surface of the body of tidal water, the buoyant element may be or be substantially out of sight and/or invisible, which may be visually appealing.

The term "tide-raised condition" used herein and throughout is defined as or intended to mean a level of the surface of the body of tidal water and/or the buoyant element being high relative to the support element. When the level of the surface of the body of tidal water is in the top half of the tidal range, the body of tidal water and/or the buoyant element may be considered to be a fide-raised condition. In other words, the fide-raised condition may be considered to start half-way between low tide and high tide when the surface is rising, and end half-way between high fide and low tide when the surface is falling.

Similarly, the term "fide-lowered condition" used herein and throughout is defined as or intended to mean a level of the surface of the body of tidal water being low relative to the support element and/or the buoyant element. When the level of the surface of the body of tidal water is in the lower half of the tidal range, the body of tidal water and/or the buoyant element may be considered to be a tide-lowered condition. In other words, the tide-lowered condition may be considered to start half-way between high tide and low tide when the surface is falling and end half-way between low tide and high tide when the surface is rising.

The term "harnessing" used herein and throughout is defined as or intended to mean to use and/or extract energy from a natural resource, especially to produce electricity.

Optionally the growth promotor may comprise a surface coating of the buoyant element. 20 Preferably, the surface coating may be a surface-roughness-increasing coating.

In one embodiment, the growth promotor may comprise a nutrient source integrally formed with or impregnated into the buoyant element.

The nutrient source may comprise a fertilization system of the buoyant element.

Optionally, the growth promotor may comprise at least one artificial marine habitat 25 support structure associated with the buoyant element.

There are many possibilities for tidal farming of species which might otherwise only existing in depths which would otherwise usually prevent agricultural exploitation, and the present invention provides a synergistic means of utilising the buoyant element for this purpose.

The energy harnessing system may further comprise food harvesting equipment for harvesting animal or plant matter from the marine organism, the food harvesting equipment being powerable by the electricity generator.

Harvesting of food from the buoyant element may be improved by harvesting equipment, 5 which can be beneficially powered without the need for an external power source due to the presence of the electricity generator.

Preferably, the buoyant element may comprise a plurality of internal compartments. Additionally, at least one said internal compartment may be sealed. Whereas a buoyant element comprising a single internal compartment might take in water upon sustaining damage, lose buoyancy and sink, multiple compartments may permit the buoyant element to sustain damage whilst remaining sufficiently buoyant.

Optionally, at least one said internal compartment may have a hexagonal cross-section. Preferably, a plurality of said internal compartments may form a hexagonal lattice structure. A hexagonal lattice or honeycomb structure provides optimal packing and 15 strength of the compartments.

Beneficially, the buoyant element may comprise recyclable waste. Alternatively or additionally the buoyant element may comprise unrecyclable waste. Furthermore, the waste may comprise plastics. The buoyant element is environmentally friendly by using recyclable or recycled materials, rather than primary materials. Repurposing or reusing unrecyclable, unrecycled, and/or recycled waste may reduce the cost of manufacturing the buoyant element and/or is environmentally friendly as providing a second use for waste which would otherwise be sent to landfill, buried, stored in a cavity, bunker, or mineshaft; sunk underwater such as at sea or in a lake; dispersed on land or at sea; incinerated; or otherwise disposed of, particularly in an environmentally unfriendly manner, whether immediately or at a later date. Most preferably, the buoyant element comprises plastics. Recycled plastics may be formed or moulded into a desirable shape or structure. Furthermore, the buoyant element may be at least partly underwater and out of sight, preferably at all times. As such, the buoyant element may be or be substantially out of sight and/or invisible, which may be visually appealing. As the buoyant element may comprise waste material, the energy storage system may have a low, or even a positive environmental impact.

Optionally, said waste may be contained within at least one said internal compartment. Additionally or alternatively, at least one said internal compartment may contain a buoyancy-providing element. The average density and the mass distribution of the buoyant element may be fine-tuned by selectably filling one or more internal compartments.

Additionally or alternatively, at least one said internal compartment may have a wall comprising said waste. The wall or walls of the compartments may be formed at least in part of waste, which is environmentally friendly.

Preferably, the buoyant element may comprise a through-bore for receiving the support element therethrough such that the support element prevents or inhibits lateral displacement of the buoyant element. Additionally, the buoyant element may comprise at least two contact portions which may be simultaneously abuttable against the support element, the at least two contact portions being vertically spaced-apart for inhibiting tilting of the buoyant body relative to the support element. Furthermore, the support element may comprise any of: a pole, a pylon, and a tower. The interaction of the through-bore and the support element limits any horizontal displacement and/or any rotation about a horizontal or substantially horizontal axis.

Beneficially, the support element may comprise a support tower of an offshore wind turbine. The installation may be facilitated if the support element is already in place. The support element may be retrofittable to an existing structure. The energy harnessing system may even comprise an offshore wind turbine. The energy harnessing system may harness energy from at least two distinct renewable energy sources.

Preferably, the buoyant element may have a toroidal body. This profile may provide a more aerodynamic and/or hydrodynamic profile, at least compared to a polygonal profile, 25 thereby minimising lateral drag forces, and prolonging the life of the energy harnessing system.

Furthermore, the buoyant element may have a square toroidal body or a rectangular toroidal body. An upper surface of the buoyant element may be flat or substantially flat, such that the upper surface may be walked upon. This may increase the ease of 30 maintenance.

Beneficially, the buoyant element may be devoid of or may not comprise a hull. A hull may result in an unequal distribution of the mass of the buoyant element. This would in turn increase the stresses acting upon the energy harnessing system.

Beneficially, the electricity generator may be a dynamo electric generator. Direct current 5 may be produced.

Furthermore, the energy harnessing system may further comprise a connector for coupling the buoyant element to the electricity generator. Additionally, the connector may comprise at least one of: a cable, a rope, and a chain. Additionally or alternatively, the connector may include, for example, a cogged rail or any other connection element or connection means. The connector converts mechanical, linear and/or vertical translation of the buoyant element into rotational motion. The connector may also enable the electricity generator to be spaced-apart from the buoyant element. Preferably, the electricity generator is above the surface of the body of tidal water at all times.

Optionally, the locking means may in-use be in one of: an engaged condition, a disengaged condition, and a braking condition, wherein when the locking means is in the braking condition, a speed of translation of the buoyant element rising due to buoyancy or falling under gravity is reduced for enabling electricity generation to continue during at least part of a slack water period.

The term "slack water period" used herein and throughout is defined as or intended to mean a period when the flow velocity of the tidal current is or is substantially zero. Consequently, the level of the surface of the body of tidal water is or is substantially unchanging. The slack water period is typically considered to start up to two hours, and more preferably, up to 1.5 hours prior to high fide or low fide. The slack water period is also typically considered to end up to two hours, and more preferably up to 1.5 hours after high tide or low tide. It could easily be envisioned however that the slack water period may start and/or stop earlier or later than two hours prior to high fide or low tide.

When the locking means is in a braking condition, the surface of the water rises, at least initially, relative to the translating buoyant element. The buoyant element therefore has positive buoyancy and rises, albeit more slowly compared to an unlocked buoyant element freely rising due to positive buoyancy. In other words, the buoyant element acquires a lag. As the body of tidal water enters the slack water period around high tide, the rise of the water surface slows to a halt. However, the energy harnessing system continues to generate electricity due to the rising buoyant element which still has positive buoyancy.

Similarly, when the locking means is in the braking condition and the surface of the water is falling relative to the translating buoyant element, the buoyant element gains potential energy. The buoyant element falls due to gravity, albeit more slowly than the surface of the body of tidal water and/or relative to an unlocked buoyant element in free fall. When the body of tidal water enters the slack period around low tide, the energy harnessing system continues to generate electricity due to the slowed fall of the buoyant element driving the generator.

In either scenario, the generation of electricity continues, even in the absence of vertical translation of the surface of the body of tidal water. Furthermore, the supply of electricity may be continuous or substantially continuous. In other words, the supply of electricity may be smoothed out.

According to a second aspect of the invention, there is provided a method of harnessing energy from a body of tidal water for generating electricity, the method comprising the steps of: a] providing an energy harnessing system, preferably in accordance with the first aspect of the invention; b] generating electricity when the buoyant element rises vertically and/or falls or is lowered vertically. Furthermore, the buoyant element may rise due to having positive buoyancy. Additionally, the buoyant element may be lowered or may fall due to gravity. Electricity is generated by the buoyant element translating in either direction, whether due to rising and falling with the tide whilst having neutral buoyancy, rising due to having positive buoyancy after being locked below a level at which the buoyant element has neutral buoyancy, or falling under gravity.

According to a third aspect of the invention, there is provided a method of extracting energy from a body of tidal water and using said energy to selectably generate electricity, the method comprising the steps of: a] locking a vertical position of a buoyant element when the said body of tidal water is in a fide-raised condition and waiting for a surface of the body of tidal water to fall for storing energy from the body of tidal water as potential energy, or locking a vertical position of the buoyant element in a tide-lowered condition and waiting for a surface of the body of tidal water to rise for storing energy from the body of tidal water as buoyancy energy; b] releasing the buoyant element such that vertical translation of the buoyant element due to gravity or buoyancy drives an electricity generator. Energy can be predictably extracted from the vertical movement of the tide, stored and converted into electricity as required.

Furthermore, the buoyant element may be fully submergible below a surface of the body of tidal water. The buoyant element may remain fully operational or functional to store energy and/or generate electricity, regardless of the level of the surface of the body of tidal water, even when completely underwater. The buoyant element may even be submerged at all times, except when locked when the body of tidal water is in a tide-raised condition.

According to a fourth aspect of the present invention, there is provided an energy harnessing system for generating electricity from a body of tidal water, the energy harnessing system comprising: a support element suitable for installation in a body of tidal water; a buoyant element which is vertically translatable with respect to the support element in two opposing directions, the buoyant element having a buoyancy which enables flotation at or adjacent to a surface of the said body of tidal water; an electricity generator for generating electricity from the vertical translation of the buoyant element; and a locking means for locking a vertical position of the buoyant element relative to the support element, so that, when the body of tidal water is in a tide-raised condition, the buoyant element is lockable by the locking means and then releasable to fall under gravity thereby driving the electricity generator once the surface of the body of water has lowered relative to the buoyant element, and when the body of tidal water is in a fide-lowered condition, the buoyant element is lockable by the locking means and then releasable to rise due to said buoyancy thereby driving the electricity generator once the surface of the body of water has risen relative to the buoyant element.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic cut-away side view of a first embodiment of an energy harnessing system, in accordance with the first aspect of the invention; Figure 2 shows a diagrammatic cut-away plan view along the line AA in Figure 1, with part cut-away portions showing an internal hexagonal lattice structure; Figure 3 shows a diagrammatic cut-away side view of the energy harnessing system of Figure 1, in-use in a tide-lowered condition; Figure 4 shows a diagrammatic cut-away side view of the energy harnessing 10 system of Figure 3, in which a buoyant element is locked below a surface of the body of tidal water, thereby storing energy as buoyant energy; Figure 5 shows a diagrammatic cut-away side view of the energy harnessing system of Figure 1, in-use in a tide-raised condition; Figure 6 shows a diagrammatic cut-away side view of the energy harnessing 15 system of Figure 5, in which the buoyant element is locked above the surface of the body of tidal water, thereby storing energy as potential energy; Figure 6A shows a diagrammatic cut-away side view of a further embodiment of an energy harnessing system; Figure 7 shows a diagrammatic perspective view of a further embodiment of an 20 energy harnessing system, in accordance with the first aspect of the invention, Figure 8 shows a diagrammatic cut-away side view of a further embodiment of an energy harnessing system, in accordance with the first aspect of the invention, in which an in-use locking means is in a braking condition such that a buoyant element lags by descending more slowly than a surface of a body of tidal water whilst generating electricity; Figure 9 shows a diagrammatic cut-away side view of the energy harnessing system of Figure 8, in which the buoyant element generates electricity during a slack water period; and Figure 10 shows a diagrammatic cut-away side view of a further embodiment of an energy harnessing system, in accordance with the first aspect of the invention, in which an electricity generator and a locking means are within a buoyant element.

Referring firstly to Figure 1, there is shown an energy harnessing system indicated 5 generally at 10 for generating electricity from a body of tidal water 12. A surface of the body of tidal water 12 is indicated as waves in Figure 1. The energy harnessing system 10 extracts, harvests, or harnesses energy from the body of tidal water, and may be referred to as a tidal-range energy converter, a buoyancy and potential energy system, a tidal-energy capture system, a tidal energy harvesting system, a tidal-energy electricity 10 generation system or converter. The energy harnessing system 10 comprises a support element 14, a buoyant element 16 and an electricity generation means 18. The energy harnessing system 10 further comprises a locking means 20 but this feature may be omitted.

The support element 14, also referred to as an anchoring element, is suitable, configurable, configured, adapted, or adaptable for installation in the body of tidal water 12. The support element 14 is at a fixed position in the preferred embodiment, but non-fixed may be envisioned, such as semi-permanently fixed or movable by way of example only. Preferably, the support element 14 in-use is at least partly in and/or surrounded by the body of tidal water 12 at all times. The support element 14 is preferably offshore. The support element 14 enables the buoyant element 16 to be geostationarily or near geostationarily constrained. The support element 14 preferably also enables the buoyant element 16 to be suspendable or suspended. Optionally, the support element 14 may enable the buoyant element 16 to be submerged or submergible. The support element 14 preferably comprises an elongate support portion 22.

The elongate support portion 22 is preferably vertical or substantially vertical but non-vertical may be envisioned. The elongate support portion 22 may be hollow, partly hollow, or non-hollow. The elongate support portion 22 may comprise metal, plastics, concrete, cement, wood, any suitable material, or any combination thereof. More preferably, the support element 14 comprises any of: a pole, a pylon, a tower, and a pole- like structure. In the present embodiment, the support element 14 comprises the support tower of an offshore wind turbine, but alternatives such as a telecommunications mast, a mooring pole, or any other suitable support may be envisioned. As an alternative to being at a fixed position in the body of tidal water 12, the support element may be semi-permanently in position. An example of a support element being at a semi-permanent position may be a leg or support of an offshore oil platform. The oil-platform may be in a given, set, or fixed position for a length of time, before being moved to a further position. The support element 14, and more preferably the elongate support portion 22 thereof, has a longitudinal extent.

The longitudinal extent or height extends at least between the said tide-raised condition and the said tide-lowered condition, for in-use enabling the buoyant element 16 to be locked at either level. More preferably, the support element 14 extends at least between the level of the water surface reached at high fide and the level reached at low tide during at least neap fides, and more preferably during spring fides. In the present embodiment, the elongate support portion 22 extends from a bed or bottom of the body of tidal water 12 as shown. The elongate support portion 22 preferably extends beyond the highest high-tide level reached at any point of the year. The elongate support portion 22 also has a lateral cross-section, which is curved, although non-curved may be envisioned.

Preferably the cross-section is or is substantially circular in the present embodiment, but non-circular may be an option, for instance, an ellipse, an oval, a polygon, whether irregular or regular, such as a square, a rectangle, whether chamfered or non-chamfered.

Optionally, the support element 14 may comprise a first engagement portion 24, shown in Figures 1 and 2. The first engagement portion 24 may extend, preferably linearly, along all or at least a major portion of the longitudinal extent of the elongate support portion 22, although a minor portion and/or non-linearly may be envisioned. Preferably, the first engagement portion 24 may comprise any of: a male portion, a female portion, a recess, a ridge, a groove, a dimple, a rail, a projection, a slit, a slot, or any other suitable engagement means. There may be a plurality of engagement portions 24. As best shown in Figure 2, the first engagement portion 24 may be curved in lateral cross-section. Most preferably, the first engagement portion 24 is concave in lateral cross-section.

Furthermore, the support element 14 may also comprise a receiving conduit 26, shown in Figures 1 and 2, although this feature may be omitted. The receiving conduit 26 may optionally be positioned opposite the first engagement portion 24 in lateral cross-section.

The receiving conduit 26 may be closed, or preferably as shown, open. The receiving conduit 26 may comprise any of: a channel, a recess, a protrusion, one or more hooks, a slit, a slot, a groove, a tube, a pipe, and a pipe section. Similarly to the first engagement portion 24, the receiving conduit 26 extends along preferably all, or at least a major portion of the support element 14, although a minor extent may be an option.

The buoyant element 16 has a buoyancy which enables or permits flotation thereof when in or on a body of tidal water 12. The buoyant element 16 may be referred to as a floating 5 element or a float. The buoyant element 16 may have a preferred position or position at which it has neutral buoyancy.

Neutral buoyancy occurs when the gravity force and the buoyant force or lift due to buoyancy acting upon an object cancel each other out. As such, the buoyant element 16 neither sinks nor rises when neutrally buoyant. If vertically displaced from a level at which the buoyant element 16 has neutral buoyancy, the gravity force or the buoyant force do not cancel each other out such that the buoyant element 16 is biased to rise or sink to return to neutral buoyancy.

At neutral buoyancy, the buoyant element 16 preferably floats at or adjacent to a surface of the said body of tidal water 12. Preferably, as shown, at neutral buoyancy, an in-use upper part of, or at least an upper surface of the buoyant element 16 is above the surface, whilst an in-use lower part or at least a lower surface of the buoyant element 16 is below the surface of the body of tidal water 12. However, in an alternative embodiment, the whole or entire buoyant element may be fully on or above the surface of the body of tidal water. Alternatively, the whole or entire buoyant element may be fully beneath the surface of the body of tidal water whilst remaining adjacent thereto when neutrally buoyant. In other words, no part of the buoyant element may be above the surface of the body of tidal water in this alternative embodiment. The or an upper surface of the buoyant element may be below the surface when the buoyant element has neutral buoyancy. The buoyant element may therefore be submergible or submersible below the surface of the body of tidal water 12, whilst remaining functional even when partly or fully submerged.

The buoyant element 16 is in-use translatable with respect to the support element 14. More preferably, the buoyant element 16 is translatable vertically. This is due to the buoyant element 16 maintaining neutral buoyancy while the surface of the body of tidal water 12 rises and falls. The buoyant element 16 is preferably inhibited or prevented from being laterally translatable, but laterally translatable instead of or in addition to being vertically translatable may be an option. The buoyant element 16 is translatable in at least one direction, and is more preferably in two opposing directions.

The buoyant element 16 or at least a vertical position thereof is lockable and unlockable or releasable. Preferably, when the buoyant element 16 is in a locked condition, the whole of the buoyant element 16 is locked. In other words, no part of the buoyant element 16 is vertically movable, at least relative to the support element 14 when in the locked condition, although this feature may be omitted.

It may be envisioned that, when the buoyant element is in a locked condition, at least part of the buoyant element may be any of: movable, rotatable, and translatable. For example, the buoyant element may be rotatable around an axis. The axis may be horizontal or substantially horizontal. The axis may be positioned at or adjacent to a perimeter of the buoyant element, or spaced-apart therefrom. The axis may pass through a centre of gravity of the buoyant element and/or a through-bore thereof.

When in an unlocked condition, the buoyant element 16 is preferably freely translatable relative to the support element 14. The buoyant element 16 optionally has a second engagement portion 28. The buoyant element 16 also has a buoyant body 30.

The second engagement portion 28 is integrally formed with, connected or connectable to the buoyant body 30, optionally to an upper surface thereof, as shown in Figure 1, although connection to a side surface, or a lower surface additionally or instead, or neither may be envisioned. Optionally, the second engagement portion 28 may extend along all or at least part of a thickness, width and/or length of the buoyant body 30. The second engagement portion 28 may be formed of metal, plastics, concrete, cement, any other suitable material, or any combination thereof In the present embodiment, the second engagement portion 28 is triangular in side view and rectangular in plan view, but non-triangular and/or non-rectangular may be envisioned. The second engagement portion 28 may be any shape in lateral and/or longitudinal cross-section, such as curved, part curved, non-curved, circular, non-circular, polygonal, whether irregular or regular such as square, rectangular, triangular, hexagonal, octagonal, whether chamfered or rounded, or any other suitable shape or geometry. The second engagement portion 28 may have at least one groove, slit or slot and/or at least one projection or protrusion. Furthermore, the second engagement portion 28 is, preferably complementarily, abuttable, engageable or engaged with the first engagement portion 24. In the present embodiment, the second engagement portion 28 is at least in part engageable with the first engagement portion 24. As shown, the second engagement portion 28 is at least in part receivable in or on the first engagement portion 24. Furthermore, the second engagement portion 28 may be rollable and/or slidable relative to the first engagement portion 24. The interaction of the first and second engagement portions 24,28 has a function of guiding the buoyant element 16. The interaction of the engagement portions 24,28 may also prevent or inhibit rotation at any given level around the support element 5 14. In other words, lateral movement, whether translation relative to the support element 14 and/or rotation around the support element 14 may be prevented or inhibited. The interaction of the engagement portions 24,28 may optionally prevent or inhibit tilting of the buoyant element 16 or rotation about a horizontal or substantially horizontal axis of rotation. Thus, the buoyant element 16 is preferably non-tiltable and/or non-rotatable, 10 although tiltable and/or rotatable may be envisioned.

The buoyant body 30 is the part of the buoyant element 16 which floats. The buoyant body 30 has an average density and mass. Preferably, said average density and/or mass is carefully selected to enable the buoyant body 30 to float but also to maximise potential energy if the buoyant body 30 is suspended above the level at which it has neutral buoyancy.

Potential energy is a function of mass such that the greater the mass of the buoyant element 16, the more potential energy is stored. Denser materials are therefore preferred. However, the buoyant element 16 and/or buoyant body 30 must also be sufficiently buoyant to rise towards the surface. The average density of the buoyant body 30 is therefore carefully fine-tuned to fulfil both requirements simultaneously. The optimal density of the buoyant element 16 and/or buoyant body 30 is slightly less than that of the body of tidal water 12. If the body of tidal water is freshwater, the relative density of the buoyant element 16 may be below 1. As the density of surface saltwater is typically about 1020 kg/m3, the density of the buoyant element 16 is preferably less than 1020 kg/m3.

The buoyant body 30 may comprise a ballast mass, in other words, a filler material. The ballast mass may optionally be enclosed in a shell. The ballast mass and the shell may comprise different materials but may be formed of the same material or materials and/or there may be an overlap in the materials. They may even be integrally formed, and/or form a monolithic structure or single mass without any boundaries or seams.

The buoyant body 30 and in particular, the ballast mass and/or the shell may comprise waste and/or non-waste. Waste material is understood to be material which has had a prior use, whilst non-waste material has had no prior use. Typical non-waste materials may include plastics, metal, concrete, cement, wood, water, fluids, liquids, or any other suitable material or combination thereof Waste material may comprise any or any combination of metal, coal, ash, soil, debris, demolition material, gravel, rocks, building waste, plastics, concrete, cement, water, fluids, liquids, wood, or any other suitable material. The waste material or materials may be recycled, recyclable, unrecyclable or non-recyclable, or any combination thereof. Repurposing or reusing unrecyclable, unrecycled, and/or recycled waste may reduce the cost of manufacturing the buoyant body 30 and/or is environmentally friendly as providing a second use for waste which would otherwise be sent to landfill; buried, stored in a cavity, bunker, or mineshaft; sunk underwater such as at sea or in a lake; dispersed on land or at sea; incinerated; or otherwise disposed of, particularly in an environmentally unfriendly manner, whether immediately or at a later date. Most preferably, the buoyant body 30 comprises recycled plastics. Recycled plastics may be formed or moulded into a desirable shape or structure. The support element 14 is preferably monolithic.

The buoyant body 30 is axially translatable, in other words translatable along an axis.

The axis preferably is or is substantially parallel to, aligned with and/or co-axial with a longitudinal axis of the support element 14. The buoyant body 30 comprises an axially-facing major upper surface 31a and an axially-facing major lower surface 31b, herein and throughout referred to as an upper surface and a lower surface respectively for clarity. The buoyant body 30 also comprises at least one perimeter wall 31c, extending between the upper surface and the lower surface 31a,31b. The at least one perimeter wall or peripheral wall 31c is preferably contiguous to one of or both the upper and the lower surfaces 31a,31b. As shown in Figure 2, the buoyant body 30 has a circular perimeter wall, although non-circular may be envisioned, such as curved, non-curved, part curved, linear, non-linear, an elliptical, oval, polygonal, whether irregular or regular, such as square, rectangular, whether chamfered or non-chamfered. The buoyant body may be cylinder, a prism, such as a rectangular or square prism. The buoyant element 16 preferably is devoid of or does not comprise a hull and/or is not a ship or vessel, but these options may be envisioned. The buoyant body 30 may have a major dimension and/or a minor dimension. Preferably, a major dimension and/or a minor dimension of the buoyant body 30 is at least 50 metres in length, and more preferably at least 100 metres in length. Most preferably, a major dimension and/or a minor dimension of the buoyant body 30 may be at least 150 metres in length. Here, the major dimension is the same as the minor dimension, and both are a diameter of the buoyant body 30, but this need not be the case. The buoyant element 16 may provide a shelter and/or a substrate for fauna and/or flora to settle in, on, or under. In other words, the buoyant element 16 may provide a habitat and/or may be wildlife friendly. Optionally, the buoyant element 16 or part thereof, such any of the upper surface 31a, the lower surface 31b, and the perimeter wall 31c, may comprise a wildlife-friendly coating and/or surface texture which may encourage or enhance wildlife colonisation. Preferably, the buoyant element 16 also comprises a through-hole or through-bore 32, as shown in Figure 2, but this feature may be omitted.

The through-bore 32 extends from an upper surface of the buoyant element 16 to a lower surface thereof. The through-bore 32 is preferably suitably dimensioned and shaped to receive the support element 14 therethrough. In other words, the buoyant element 16 preferably surrounds or encloses the support element 14, and in particular the elongate support portion 22 thereof. This enables the support element 14 to in-use restrict, constrain, limit, prevent or inhibit lateral or horizontal displacement of the buoyant element 14 at a given level and/or reduce any moments when the buoyant element 16 is locked and suspended above the surface of the body of tidal water 12. Preferably, the through-bore 32 and the support element 14 are complementarily shaped. In the present embodiment, the through-bore 32 is circular in lateral cross-section. A wall or walls defining the through-bore 32 is or is substantially planar or linear in longitudinal cross-section, although non-planar or non-linear may be envisioned, such as curved, part-curved, polygonal, whether regular, irregular, or chamfered. The through-bore 32 is preferably centrally positioned, although offset therefrom is an option. As such, the buoyant element 16 may be a, preferably coaxial, annulus in plan view. In other words, the buoyant element 16 may be an annular cylinder or a toroid. In yet again other words, the buoyant element 16 may have a toroidal body.

The term "toroid" used herein and throughout is defined as or intended to mean a surface and/or volume, in other words a shape formed by at least part of, and preferably a whole revolution around an axis of revolution of a two-dimensional geometric figure, and having a hole or through-bore in the middle. The axis of revolution passes through the hole, preferably without intersecting the surface and/or volume. A toroid includes, but is not limited to, any toroidal polyhedron, any elliptical torus or torus resulting from the revolution of an ellipse, or a circular torus or torus resulting from the revolution of a circle.

The term "toroidal polyhedron" used herein and throughout is defined as or intended to mean a surface and/or volume, in other words a shape formed by any polygon having undergone at least part of, and preferably a whole revolution or rotation around an axis.

The toroidal polyhedron also comprises a through-bore. Examples of toroidal polyhedrons include a square toroid and a rectangular toroid. The polygon may be regular, irregular, chamfered, and/or rounded. The polygon may even have at least one curved edge and/or a rounded corner.

Furthermore, the cross-sectional dimensions of the through-bore 32 are similar to the cross-sectional dimensions of the elongate support portion 22, to provide a snug fit. The absence of any slack reduces the risk of the buoyant element 16 damaging the elongate support portion 22 in rough conditions. The snug fit may also prevent or inhibit the buoyant body 30 from being tiltable. For instance, the buoyant element 16 may comprise at least two contact portions or points which are simultaneously abuttable against the support element 14, the at least two contact portions being in-use vertically spaced-apart or overlying or overlapping each other for inhibiting tilting of the buoyant body 30 relative to the support element 14.

The buoyant element 16 and in more preferably, the buoyant body 30 may optionally further comprise at least one, and here a plurality of compartments 34, also referred to as pockets, or cells, as shown in Figures 1 and 2, but no compartments may be envisioned. At least one said compartment 34 may be internal but this need not be the case. At least one, and preferably all said compartments 34 are sealable or sealed, but all, or at least one internal compartments may not necessarily be sealed. In other words, one or more compartments may be open.

Optionally, it may even be envisioned that the or at least one said compartment 34 may be open or have at least one opening, access, aperture, perforation, or gap on or in the in-use lower surface 31b of the buoyant body 30. Such a compartment 34 may be otherwise watertight or airtight, and may be filled with or may contain a buoyancy-providing element, such as but not limited to air. In-use, the surface of the body of water 12 may seal the at least one opening, preventing, or inhibiting the buoyancy-providing element from escaping from the compartment 34. Simultaneously, the buoyancy-providing element opposes, inhibits, or prevents entry of water into the or each such compartment 34. The buoyancy-providing element may or may not be compressible and/or compressed. The buoyant body 30 or at least one compartment 34 thereof may be a caisson, and more preferably a compressed air caisson.

Each internal compartment 34 may be regular or irregular in shape and/or size. In lateral and/or longitudinal cross-section, each, all, or at least one internal compartment 34 may be any of: curved, non-curved, part-curved, rounded, circular, non-circular, elliptical, oval, ovoid, aerofoil shaped, hydrodynamically or aerodynamically shaped, polygonal such as square, rectangular, triangular, hexagonal, octagonal, whether irregular or regular, chamfered or non-chamfered, or any other desirable shape may be envisioned.

For example, at least one internal compartment may be a sphere, a cube, a rectangle, a regular or irregular polyhedron, a prism. The internal compartments 34 are all identical to each other but it may be envisioned that the buoyant body may comprise at least two differently shaped and/or differently sized internal compartments. A plurality of internal compartments 34 may form a lattice structure or a foam structure. The lattice structure or foam structure may be regular or irregular. The lattice structure or foam structure preferably comprises at least two internal compartments 34 having the same cross-section. Additionally or alternatively, the lattice structure or foam may comprise at least two internal compartments 34 which have a different cross-section. At least two compartments 34 may be adjacent to each other and/or may share a wall. The, each or at least one compartment 34 may extend from or substantially from an in-use upper surface to an in-use lower surface of the buoyant element 16, as shown in Figure 1. In other words, there is preferably one layer of compartments 34, but any number of layers, including at least two, may be envisioned.

Additionally or alternatively, the, each or at least one compartment 34 may extend from or substantially from an in-use side surface to a further in-use side surface of the buoyant body 30. In the case of a circular buoyant body 30 comprising a single side or perimeter wall, one or more compartments 34 may extend along part of a chord or a diameter of the buoyant body 30, although this feature may be omitted. The, each or a said compartment may have any cross-sectional area and/or volume, up until and including the maximum area and/or volume of the buoyant body 30.

In the illustrated embodiment, at least one, and preferably all said internal compartments 34 have a hexagonal cross-section. An example of such hexagonal compartments 34 are shown in Figure 2 through part cut-away portions. A plurality of said internal compartments 34 may form a hexagonal lattice, such that the buoyant body 30 may comprise a hexagonal lattice structure or honeycomb structure. Such a structure provides an optimised packing and/or strength of the compartments and provides robustness to structural failure and damage. Although a hexagonal lattice structure is preferred, any non-hexagonal lattice structure may be envisioned.

At least one said compartment 34 may be filled with a buoyancy-providing element. Said buoyancy-providing element is preferably air, but any other desirable buoyant fluid or fluids and/or solid or solids may be envisioned, such as one or more gases or a gaseous mix, one or more liquids, a mixture, or one or more compounds. The gas or gaseous mix may comprise any of: Oxygen, Carbon Dioxide, Nitrogen, Helium, and any other suitable gas, or combination of gases. Furthermore, at least one said internal compartment 34 may have a wall comprising said waste. Additionally or alternatively, waste and/or non-waste as described above may be contained within at least one said internal compartment 34. For example, concrete may be contained within at least one internal compartment 34. Preferably, if the ballast mass and/or the buoyancy-providing elements are distributed amongst at least two internal compartments 34, said plurality of compartments 34 are preferably distributed across the buoyant body 30, although this feature may be omitted. A compartment 34 may even comprise both a buoyancy-providing element and ballast mass material.

Segmentation or compartmentalisation and distribution of the ballast mass distributes the mass of the buoyant element 16 whilst segmentation or compartmentalisation and distribution of the buoyancy-providing elements provides a more uniform density across the buoyant element 16. These features are advantageous, should the buoyant body 30 sustain any damage. For example, if part of the buoyant body 30 is broken off such that an opening is created into one or a subset of compartments 34, any influx of water is restricted to that compartment or subset of compartments 34. The remainder of the ballast mass in other compartments is or is substantially unaffected. Similarly, the average density of the whole buoyant body 30 is also unaffected or substantially unaffected. Thus, the buoyant element 16 remains functional or substantially functional despite sustaining damage. Smaller compartments 34 are advantageous to restrict and limit the effect of any damage. However, larger compartments may be advantageous for ease of manufacture.

In comparison, upon sustaining damage, a single-compartment buoyant body may fill up with water. Such a buoyant body may sink, thereby having reduced functionality or no longer being functional. Alternatively, the damaged single-compartment buoyant body may lose part or all of the ballast mass, such that less potential energy may be stored, as potential energy is a function of mass.

The electricity generation means 18 enables the energy harnessing system 10 to generate electricity. The electricity generation means 18 comprises at least one electricity generator 36a, and a connection means 36b, although the latter feature may be omitted.

The or each electricity or electric generator 36a in-use generates electricity from the translation of the buoyant element 16. The, each or at least one said electricity generator 36a may be a dynamo electric generator, which provides direct current. Alternatively or additionally, the, each or at least one said electricity generator 36a may be an alternator providing alternating current. The or each electricity generator 36a is preferably positioned at, in or on the support element 14 and/or above or actually in or on the buoyant element 16. Furthermore, the or each electricity generator 36a is positioned above the surface of the body of tidal water 12, at least part of the time, and preferably at all times. The or each electricity generator 36a is therefore not submerged or underwater.

It could be envisioned however, that the or a said generator may be underwater at least some or all of the time.

The, each or at least one said electric generator 36a may comprise a rotatable protrusion, such as a shaft or wheel, which the connection means 36b may be wrapped around and/or engageable with, such as via friction, via teeth and/or any other suitable 20 engagement means.

The connection means 36b in-use connects or couples the buoyant element 16 to the electricity generator 36a. The connection means 36b may be referred to as a connector, an entrainment means, a connection line, a mechanical converter, or a movement-transmission means. The connection means 36b comprises at least one elongate element. The elongate element or part thereof is preferably at least partly flexible, pliable, wrappable or spoolable, although non-flexible, such as a rigid or partly rigid connector, may be envisioned. More preferably, the connection means 36h comprises at least one of: a cable, a rope, and a chain, although any other suitable connector may be envisioned. An example of a rigid connector may include a pole or shaft. The rigid connector may extend from the buoyant element to the electricity generation means 18. The connection means 36b or the connection means 36b and the buoyant element 16 together may form a complete or close loop, as in the present embodiment, but an open loop may be envisioned. The connection means 36b in-use extends between the electricity generator 36a and the buoyant element 16. In the present embodiment, the connection means 36b is connectable, connected, and/or integrally formed with the second engagement portion 28, but the connection means may instead be disconnected and/or non-connectable therewith. The connection means 36b is positioned inside the support element 14, but may alternatively be outside or partly outside the support element may be envisioned. Preferably, the connection means 36b is at least in part received within the said receiving conduit 26, as best shown in Figure 2. The receiving conduit 26 is preferably a recess, such that the connection means 36b is received or guided within the receiving conduit 26. The connection means 36b may also be at least in part received within the through-bore 32, although this feature may be omitted. In Figures 1 and 2, the connection means 36b, which is preferably a chain, is illustrated as dotted lines in Figure 1. In Figure 2, the two dots represent a cross-section through a chain link of the connection means 36b received within the receiving conduit 26. As the connection means 36b is preferably a closed loop, a second section of the connection means 36b might be expected in Figure 2. However, as the connection means 36b is preferably encased in the second engagement means 28, said second section is not visible in this instance.

The electricity generation means 18 further comprises a guiding portion 38, but this feature may be omitted. The guiding portion 38 in-use guides the connection means 36b and/or maintains at least part of the connection means 36b taut or tensioned. The guiding portion 38 may be referred to as a connector support, or anchoring element. The guiding portion 38 is associated with the support element 14 and spaced-apart from the electricity generator 36a. Preferably, the guiding portion 38 is positioned below the receiving conduit 26 but this feature may be omitted. The guiding portion 38 is positioned below the surface of the body of tidal water 12, at least part of the time, and preferably at all times. In the present embodiment, the guiding portion 38 comprises at least one pulley. Additionally or alternatively the guiding portion may comprise one or more protrusions and/or grooves in, on, or around which the connection means may be receivable and/or slidable. The guiding portion 38 enables part of the connection means 36b to extend beneath the buoyant element 16.

The locking means 20 in-use enables locking of a vertical position of the buoyant element 16 relative to the support element 14 and/or relative to the surface of the body of tidal water 12. The locking means 20 is preferably associated with the support element 14. The locking means 20 is preferably fixed relative to the support element 14 and/or relative to the guiding portion 38 but non-fixed relative thereto may be envisioned. More preferably, the locking means 20 is mounted at, in or on the support element 14. The locking means 20 may selectably lock the electricity generation means 18 or any part or parts thereof. In particular, the locking means 20 engages with the connection means 36b but may additionally or alternatively lock the guiding portion and/or the, each or a said electricity generator. The locking means 20 may be comprise a clamp or clamping element.

Optionally, the energy harnessing system 10 may further comprise a control unit, not shown. Said control unit may comprise or store at least one control algorithm. The or each control algorithm may determine when and/or at which level relative to the support element 14 the buoyant element 16 should be locked or unlocked. This enables optimisation of the storage and/or electricity generation. The energy harness system 10 may even comprise one or more sensors. Such a sensor may in-use detect the level of the buoyant element 16 relative to the support element 14 and/or relative to the surface of the body of tidal water 12, by way of example only.

In-use, the energy harnessing system 10 may need to be installed first. The energy harnessing system 10 may be provided as a kit, and thus may be in a partly or fully disassembled condition.

The support element 14 is moved to a suitable site and fixed or anchored in position.

Optionally, a foundation is provided or formed and the support element 14 is fixed thereto or thereby, for example by a fastener such as bolts or by being encased in the foundation. Alternatively, the energy harnessing system 10 may be retrofitted to an existing support element 14 such as an existing mooring or the body of a wind turbine.

Any of the buoyant element 16, the electricity generation means 18, the locking means 25 20, or any part of either, may be installed before or after fixing the support element 14 in position The electricity generator 36a is positioned preferably at or adjacent an end, preferably the in-use top end, of the support element 14. If provided, the guiding portion 38 is preferably associated with the opposing end of the support element 14 and/or is positioned spaced-apart from the electricity generator 36a. The guiding portion 38 is at or adjacent to the bed of the body of tidal water 12 but spaced-apart therefrom may be envisioned.

The buoyant element 16 is appropriately positioned relative to the support element 14. In the present embodiment, this involves positioning the buoyant element 16 around the support element 14. The buoyant body 30 may optionally be in two or more separate parts which may be engageable, whether separably or permanently with each other to form the through-bore 32. This may be necessary if the buoyant element 16 is to be retrofitted to an existing support element 14. The first and second engagement portions 24,28 are engaged with each other.

The connection means 36b is engaged with or connected to the buoyant element 16 before, during or after positioning the buoyant element 16 relative to the support element 14. The connection means 36b is wrapped around the guiding portion 38 at one end and around the electricity generator 36a at the other, extending therebetween, preferably received within the receiving conduit 26 if provided. The connection means 36b forms a closed loop in the present embodiment, with itself or together with the buoyant element 16.

The locking means 20 may be installed at any point.

The assembled energy harnessing system 10 may be used to generate electricity and/or to store energy.

To generate electricity, the buoyant element 16 is in unlocked condition. The buoyant element 16 is therefore freely translatable vertically relative to the support element 14. 20 At neutral buoyancy, the buoyant element 16 floats on, at or adjacent to the surface of the body of tidal water 12 Preferably, the distance or difference between the level at which the buoyant element 16 has neutral buoyancy and the level of the surface of the body of tidal water 12 remains constant or substantially constant relative, assuming no change in the density of the 25 buoyant element 16.

The surface of the body of tidal water 12, and therefore the unlocked floating buoyant element 16, rises and falls periodically between a high-tide level and a low-tide level.

The connection means 36b, or at least the part of the connection means 36b between the buoyant element 16 and the generator 36a is preferably taut or substantially taut, but 30 this feature may be omitted.

As the buoyant element 16 rises, energy is extracted from the body of tidal water 12 and converted into kinetic energy, via the vertical translation of the buoyant body 30. The buoyant element 16 pulls or drags upwards a portion of the connection means 36b which extends between the buoyant element 16 and the guiding portion 38. In turn, the portion of the connection means 36b which extends from the guiding portion 38 to the or a said electricity generator 36a is dragged or pulled downwards and/or around the guiding portion 38. The portion of the connection means 36b which is wrapped around the or a said electricity generator 36a or part thereof, actuates or causes part of the electricity generator 36a to produce electricity, preferably here by rotation in a first angular orientation. Kinetic energy is therefore transformed into electricity. In other words, translation of the buoyant body 30 rotates the closed-loop connection means 36b around parts of the energy harnessing system 10, one of which is the or a generator 36a.

As the buoyant element 16 is lowered by the surface of the body of tidal water 12, the buoyant element 16 pulls or drags downwards the portion of the connection means 36b which extends between the buoyant element 16 and the or a said electricity generator 36a. The portion of the connection means 36b which is wrapped around the or a said electricity generator 36a, actuates or causes part of the electricity generator 36a to produce electricity, preferably here by rotation in a second angular orientation. The generator 36a is preferably therefore bi-directional, but non bi-directional may be envisioned, such as uni-directional.

There, electricity may be generated irrespective of the tidal direction. In other words, electricity can be generated when the surface of the body of tidal water 12 is rising only, falling only or, preferably, both rising and falling.

To store energy, the buoyant element 16, and more preferably, the vertical position 25 thereof, is locked.

Preferably, the buoyant element 16 is locked when the body of tidal water 12 is in a fide-raised condition. In other words, the buoyant element 16 is preferably locked when it is in a relative high position relative to the support element 14 and/or relative to the tidal range.

Locking the buoyant element 16 involves actuating the locking means 20 into an engaged condition. Here, the locking means 20 clamps the connection means 36b. As the locking means 20 is fixed relative to the support element 14, the locking means 20 prevents or inhibits any movement of the connection means 36b.

Once locked in a tide-raised condition, the buoyant element 16 does not translate vertically relative to the support element 14, irrespective of the level of the surface. 5 Preferably, the whole of the buoyant element 16 is unable to move vertically. As the surface of the body of tidal water 12 falls relative to the support element 14 and/or the level of the tide-raised condition, the surface also falls relative to the buoyant element 16. As such, the support element 16 suspends the buoyant element 16. Energy is stored as potential energy. The connection means 36b may therefore in the present 10 embodiment have a further function of suspending or tethering the buoyant element 16, although this further function may be omitted.

To generate electricity from the stored energy, the buoyant element 16 is released. This involves disengaging the locking means 20. If the buoyant element 16 is released when the surface of the body of water 12 has fallen relative to the support element 14, and/or relative to the level of the tide-raised condition, the buoyant element 16 falls under gravity, thereby translating vertically. Potential energy is converted into kinetic energy. The vertical translation drives the, each, or a said electricity generator 36a, as previously described. Detailed description of the common features is omitted for brevity.

Potential energy is a function of height. Even though the locked buoyant element 16 is vertically fixed relative to the support element 14, the distance between the locked buoyant element 16 and the level at which the buoyant element 16 has neutral buoyancy is continuously changing due to the rise and fall of the surface of the body of tidal water 12. In other words, the proportion of the usable potential energy which can be converted into electricity without being opposed by buoyancy is continuously changing. To maximise the distance between the buoyant element 16 and the level at which it is neutrally buoyant, the most effective tide-raised condition to lock the buoyant element 16 is high-fide, when the water level is highest. To optimise the amount of electricity released for any fide-raised condition, the buoyant element 16 is released at low tide, as this provides the greatest height difference before the buoyant element 16 returns to neutral buoyancy.

If the energy harnessing system is provided with a control unit, said control unit may control when the buoyant element 16 is released and/or locked.

The buoyant element 16 may alternatively be locked when in a tide-lowered condition. In other words, the buoyant element 16 is preferably locked when it is in a relative low position relative to the support element 14 and/or relative to the tidal range.

Once locked in a fide-lowered condition, the buoyant element 16 does not translate 5 vertically relative to the support element 14, irrespective of the level of the surface.

As the surface of the body of tidal water 12 rises relative to the support element 14, and/or relative to the level of the tide-lowered condition, the surface also rises relative to the locked buoyant element 16. The lift or lifting buoyant force exerted upon the buoyant element 16 becomes greater than the gravity force, such that the buoyant element 16 has a tendency to want to rise or float until it reaches its original position and/or be at neutral buoyancy. In other words, the buoyant element 16 has positive buoyancy.

However, as long as the buoyant element 16 is locked, the locking means 20 prevents or inhibits any upwards movement of the buoyant element 16. Energy is stored as buoyancy energy, which may also be referred to as flotation energy. The connection means 36b may therefore in the present embodiment have a further function of restraining, anchoring, or tethering the buoyant element 16, although this further function may be omitted.

As the surface of the body of tidal water 12 continues to rise, the buoyant element 16 may optionally be completely immersed, or submerged underwater. The buoyant 20 element 16 remains functional, even when partly or fully submerged below the surface of the body of tidal water 12 Similarly to above, to generate electricity from the stored energy, the buoyant element 16 is released. The buoyant element 16 rises due to said positive buoyancy. The vertical translation drives the or a said electricity generator 36a, as previously described. 25 Detailed description of the common features is, once again, omitted for brevity.

To maximise the distance or height from the buoyant element 16 to the level at which it has neutral buoyancy, the buoyant element 16 is preferably locked at or around low tide. The buoyant element 16 may be released at or around high tide to further maximise the distance for any given fide-lowered condition, although the buoyant element may be locked and/or released at any time.

In other words, there is provided a method of harnessing energy from a body of tidal water for generating electricity, the method comprising the steps of: a] providing an energy harnessing system; b] generating electricity when the buoyant element rises vertically and/or is lowered vertically.

In yet again other words, a method of extracting energy from a body of tidal water and using said energy to selectably generate electricity is provided. The method may comprise the steps of: a] locking a vertical position of a buoyant element when the said body of tidal water is in a tide-raised condition and waiting for a surface of the body of tidal water to fall for storing energy from the body of tidal water as potential energy, or locking a vertical position of the buoyant element in a fide-lowered condition and waiting for a surface of the body of tidal water to rise for storing energy from the body of tidal water as buoyancy energy; b] releasing the buoyant element such that vertical translation of the buoyant element due to gravity or buoyancy drives an electricity generator.

Whilst the generator is preferably dynamo electric generator in the present embodiment, any type of generator may be envisioned, for example the type of generator used with a wind turbine may be envisioned. The generator may comprise a means of selectively choosing the direction of rotation, particularly in the case of a single generator. These means may include a gear box, for example. A commutator may be provided.

Although there is one, preferably bi-directional, electricity generator in the present embodiment, more than one generator may be envisioned. There may be a plurality of dynamo electric generators and/or a plurality of alternators. For example, there may be two generators which may generate electricity only when rotated in one angular direction. If the direction of rotation to generate electricity differs between two such generators, these generators may be installed in the same orientation or configuration as each other.

Conversely, two such generators having the same direction of rotation to generate electricity, may need to be in mirrored orientations or configurations.

Although the through-bore and the elongate support portion are or are substantially circular in plan view and/or in cross-section, the through-bore, and/or the elongate support portion may be non-circular. The buoyant body has a circular perimeter and a through-bore such that it is an annulus in cross-section or plan view, but a non-annulus may be envisioned. Whilst the annulus is preferably a coaxial annulus in plan view, a non-coaxial annulus may be envisioned instead. In this case, the respective centres of the inner and outer circles of the annulus may be offset from each other. Similarly, the first engagement portion and the receiving conduit are curved in lateral cross-section but non-curved may be envisioned for either or both features. Any of the through-bore, the elongate support portion, the buoyant body, the first engagement portion, the receiving conduit or any further above-mentioned feature may have any alternative shape in plan-view, lateral and/or longitudinal cross-section, such as curved, non-curved, part-curved, rounded, circular, non-circular, elliptical, oval, ovoid, a disc, aerofoil shaped, hydrodynamically or aerodynamically shaped, polygonal whether irregular or regular, such as square, rectangular, hexagonal, octagonal, chamfered or non-chamfered, or any other desirable shape may be envisioned. The cross-section of any of the above features may optionally change along their longitudinal and/or latitudinal extent. The respective shapes of the through-bore and the perimeter of the buoyant body in lateral and/or longitudinal cross-section may differ from each other. Whilst the tide-raised condition and the tide-lowered condition preferably correspond to a water level within the top half and the lower half of the tidal range respectively, a different distribution of the tidal range may be envisioned. For example, the tide-raised condition and the tide-lowered condition may correspond to a water level within the top quarter and the lower three-quarters of the tidal range, respectively.

The range of levels at which the body of tidal water is considered to be in a fide-raised condition, or a tide-lowered condition may not correspond to a subset only of the whole 20 tidal range. For example, the tide-raised and fide-lowered conditions may correspond to a water level within the top quarter and the lower quarter of the tidal range, respectively.

There may be overlap in the range of levels at which the body of tidal water is considered to be in a tide-raised condition or in a tide-lowered condition. The body of tidal water may even be in a fide-lowered condition and/or in a fide-raised condition at any level of the 25 tidal range.

The tide-raised condition may even alternatively be defined as a level at which the surface of the body of tidal water is above the neutral buoyancy of the buoyant element. Similarly, the tide-lowered condition may alternatively be defined as a level at which the surface of the body of tidal water is below the neutral buoyancy of the buoyant element.

The material of the buoyant body may provide sufficient buoyancy and optimal mass, without requiring a ballast mass or any buoyancy-providing elements. The buoyant body may comprise only one or even no internal compartments. The buoyant body may be formed of a single bloc of buoyant material or materials.

Although there is preferably one support element, one buoyant element, one through-bore, one connection means, one elongate element, one generator, one first engagement portion, one second engagement portion, one receiving conduit, one guiding portion, there may be any number of the above features including none, one or a plurality.

In the present embodiment, there is preferably one buoyant element 16, however, there may be a plurality of buoyant elements and/or a plurality of buoyant bodies per buoyant element. At least two said buoyant elements and/or two said buoyant bodies may surround or enclose the or each support element. In other words, at least two said buoyant elements may be coaxial or substantially coaxial with the support element. Said at least two buoyant elements and/or bodies may in-use overlap or overlie one another. A buoyant element may only partly surround or enclose one or more support elements. Additionally or alternatively, the, each, or at least one buoyant element and/or body may not surround or enclose the or each support element. Such a buoyant element and/or buoyant body may not require a through-bore, although one or more through-bores may be provided. The, each, or at least one buoyant element and/or body may be positioned adjacent to and/or spaced-apart from a support element. Optionally, one or more support elements may or may substantially at least partly surround or enclose one or more buoyant elements and/or buoyant bodies.

It may even be envisioned that a support element may be connected or connectable to at least two buoyant elements. Additionally or alternatively, a buoyant element may be connectable or connected to at least two support elements. One or more rows of support elements and/or a plurality of buoyant elements may be provided. The support elements may form a network, have a lattice structure, or grid formation. The lattice structure may be diagonal or non-diagonal, such as straight. The or a subset of support elements of the lattice structure may form one or more polygons in plan view, although non-polygonal shapes may be envisioned. The polygonal shape may be regular, irregular, chamfered, and/or rounded. The polygonal shape may include any of: a square, a rectangle, a hexagon, a pentagon, a trapezium, a trapezoid, any other suitable polygon, or any combination of polygons. Non-polygons may include a shape which may be curved, part-curved, a circle, an ellipse, an ovoid, or any other suitable shape or combination of shapes may be envisioned. Support elements may not even form a shape at all. Instead, they may be randomly or substantially randomly distributed relative to each other. The buoyant elements may be positioned between a plurality of support elements. For example, the or each buoyant body may be polygonal such as hexagonal, rectangular or square, or non-polygonal, such as circular. A plurality of support elements may be provided around each buoyant body. The shape of the or each buoyant body may be complementary to the shape formed by the or a subset of support elements. A plurality of support elements may even be connectable to at least two said buoyant bodies.

It will be apparent that the provision of a buoyant element 16' in a body of water may provide a suitable structure for many additional uses in addition to energy generation. As noted, at neutral buoyancy, the buoyant element 16' floats at or adjacent to the surface of the body of tidal water 12. This means that, in most scenarios, the buoyant element 16' is partially submerged. This could allow the buoyant element 16' to act as a marine habitat. This permits the use of the buoyant element 16' for farming or other agricultural projects, as the buoyant element 16' forms an artificial tidal habitat. In effect, an artificial tidal beach is formed in the body of tidal water 12.

By way of example, and as can be seen in Figure 6A, at least one surface of the buoyant body 30', and most preferably the underwater lower surface 31b' thereof, may be configured in such a way as to promote growth of an agriculturally applicable marine species. This could be plant matter, for example, to permit growth of kelp or a similar aquatic plant, in which case, the lower surface 31b' could be formed so as to encourage anchoring or root growth of marine plants, and may even be provided with a growth promotor. This could take the form of some sort of fertilizer compound which is either impregnated into the buoyant body 30', or which can be applied to plants attached thereto via a fertilization system.

A growth promotor need not be nutritional in nature, but could instead be a promotor to attachment of the marine life in question. For example, a surface coating 31c' which is more biocompatible might be considered to be a growth promotor, which could be applied to the buoyant body 30'. Alternatively, some topological features of the buoyant body 30 itself could be considered.

A more preferred embodiment, however, given the occlusion of the lower surface 31b' of the buoyant body 30' from the sun, would be to configure the buoyant element 16' for the farming of marine animals which are adapted for tidal patterns. In particular, molluscs and bivalves, such as clams and mussels, could be farmed in this manner by ensuring that the surface of the buoyant body 30' has a sufficient surface roughness to permit the animals to cling thereto. Additionally or alternatively, the buoyant element 16' could support other artificial marine habitat support structures 39', such as ropes, which are a traditional mechanism for the farming of mussels.

The artificial tidal habitat is suitable for animal and plant growth, and advantageously allows for the animal or plant matter to be harvested in a location which is otherwise inaccessible to traditional farming techniques, or which might otherwise be a protected environment on land. The energy generation of the system may also synergistically improve the food harvesting capabilities, in that tidal power may be used to power any electrically-powerable food harvesting equipment onboard the buoyant body 30', without the need to provide an additional power source.

For instance, referring to Figure 7, there is shown a second embodiment of an energy harnessing system 110, shown in-use in a body of tidal water 12. Features of the second embodiment which are similar to the first embodiment have similar reference numerals with the prefix "1" added.

The energy harnessing system 110 of the second embodiment is similar to the energy harnessing system 10 of the first embodiment, comprising at least one support element 114, at least one buoyant element 116, and at least one electricity generation means 118. The energy harnessing system 110 may further comprise at least one locking means, at least one guiding portion 138, and at least one connection means 136b but any of the above features may be omitted. Detailed description of the common features is omitted for brevity. Preferably as shown, the energy harnessing system 110 comprises six support elements 114, two buoyant bodies 130, and eight electricity generation means 118 but any number of any of these features may be envisioned. Each buoyant element 116 may or may not be independent of another said buoyant element 116. This enables fine tuning of the supply of electricity.

The or each buoyant element 116 and/or buoyant body 130 may be connectable or connected to at least one, more preferably at least two support elements 114, and most preferably to four support elements 114. The or each said buoyant element 116 may optionally be positioned between at least two of the said support elements. More preferably, the or each buoyant element 116 may be positioned or positionable between four support elements 114 as shown. Optionally, the, each, or at least one buoyant body 130 may be polygonal, and more preferably square or rectangular in plan view, lateral and/or longitudinal cross-section. However, any alternative polygonal shape may be envisioned, such as triangular, hexagonal, octagonal, whether regular, irregular, chamfered or rounded. Any non-polygonal shape may be envisioned, such as curved, non-curved, part-curved, circular, elliptical, ovoid, or any other suitable shape. The or each buoyant element 116 preferably does not have any through-bores but at least one through-bore may easily be provided. Optionally, the buoyant element 116 may comprise at least one, and more preferably at least two above-described internal compartments.

Instead of or in addition to an elongate support portion, the support element may comprise a shielding structure, also referred to as a shield or protective element. The shielding structure may comprise any of: one or more perforated walls, piling sheets, a cage-like structure, framework, apertured enclosure or enclosure having perforations, or any other suitable structure. The perforations permit or allow water flow therethrough. Such a structure may enclose, surround or contain the buoyant element whilst permitting vertical translation thereof The shielding structure may have a protective function, by preventing or reducing damage due to the elements, such as waves, water currents, or storms. The shielding structure may therefore be considered to be a shield or a wave breaker. The structure may prevent or reduce damage from other sources, such as ships, or animals.

In any of the above embodiments, whilst the locking means is fixed to the support element and acts upon the connection means, the locking means may be movable relative to the support element and/or the guiding portion. The locking means may be fixed relative to the connection means. The locking means may be integrally formed with, optionally as a one-piece, connected or connectable with the connection means. The locking means may comprise at least one blocking, jamming or wedge element which may be abuttable against the electricity generator and/or against the guiding portion to prevent or inhibit the connection means moving therearound and/or therethrough.

Optionally, the energy harnessing system may comprise at least one further part for harnessing a further source of, preferably renewable, energy. The energy harnessing system may therefore be a hybrid energy harnessing system. The or a further part may comprise at least one solar panel. Additionally or alternatively, the or a further part may comprise a, preferably offshore, wind-turbine. The control unit, if provided, may detect the energy supplied by any or any number of the further parts. The control unit may control when the energy harnessing system needs to store energy extracted from the body of tidal water, and when electricity should be generated from the body of tidal water. The control unit may be communicable with the locking means. The control unit may respond to the electricity grid and/or to each further part harnessing energy from a further source. This may advantageously smooth out frequency fluctuations and/or provide a supply of electricity at a constant or substantially constant frequency. The control unit may even respond to and/or match the demand of electricity.

Preferably in the first and second embodiments, the locking means is either engaged or disengaged such that the buoyant element is in one of two conditions: locked or unlocked. It could be envisioned in either or both embodiments that the locking means may have a third condition in which it is partially engaged. In the partially engaged condition, the locking means may permit vertical translation of the buoyant element, but the rate of translation thereof may be reduced. The rate of translation of the buoyant element may be fixed or variable and/or selectable from a, preferably continuous, range of rates, although a non-continuous or discontinuous range may be envisioned. In other words, the locking means may act as a brake. The locking means may be referred to as a braking means or as a brake. This may be advantageous to provide a more continuous supply of energy around high tide and low tide, in other words at the tidal change. At high tide and low tide, the rate of translation of the surface of the body of tidal water slows to a halt such that at high tide and low tide, no electricity or substantially no electricity is generated when the buoyant element is in the unlocked condition. To counter this phenomenon, the locking means may be actuated into the partially engaged condition or braking condition when the surface of the body of tidal water is rising or falling. The locking means may be actuated into the partially engaged condition at any time of the cycle, for instance at the change of the tide or any time in between. The buoyant element may therefore continue to translate vertically, whether rising due to having positive buoyancy or descending or falling due to having potential energy. However, the buoyant element may translate vertically at a lower rate or speed, in other words, more slowly than the surface of the body of tidal water and/or than free fall velocity. The surface of the body of tidal water therefore rises or falls relative to the buoyant element, even when the buoyant element is in-use translating. The buoyant element therefore has positive buoyancy or potential energy.

At the tidal change and/or during slack water, the buoyant element may optionally catchup with the surface of the body of tidal water, the translation of which has slowed or stopped, or changed direction. The locking means may act as a brake and slow the translation of the buoyant element via increased friction and/or via a braking mechanism. The braking mechanism may be engageable with the support element, and/or with the electricity generation means, or part thereof. More preferably, the braking mechanism may be connectable with the connection means. The braking mechanism may optionally include a wheel or cog, which may have at least one and preferably a plurality of teeth. The braking mechanism may be rotatable, by way of example only, such that the wheel 5 or cog may engaged with the connection means. The rotation of the wheel or cog may determine the rate of movement of the connection means, and thereby, the speed of translation of the buoyant body or buoyant element. The control unit may control whether and/or when the locking means is actuated into the braking condition and/or any of: the speed of translation of the buoyant body, and the angular velocity of the wheel. The 10 control unit may have an algorithm to optimise when the locking means should be engaged.

For example, Figures 8 and 9 show a third embodiment of an energy harnessing system 210, shown in-use in a body of tidal water 12. Features of the third embodiment which are similar to the first embodiment have similar reference numerals with the prefix "2" 15 added.

The energy harnessing system 210 of the third embodiment is similar to the energy harnessing system 10 of the first embodiment, comprising at least one support element 214, at least one buoyant element 216, and at least one electricity generation means 218. The energy harnessing system 210 may further comprise at least one locking means 220, at least one compartment 234, at least one guiding portion 238, and at least one connection means 236b but any of the above features may be omitted. Detailed description of the common features is omitted for brevity.

The uses of the third embodiment are similar to the uses of the first embodiment. Detailed description of the common features is, yet again, omitted for brevity. In the third embodiment, the locking means 220 may be actuated into the braking condition, rather than the engaged condition, and at any time, but preferably when the buoyant element 216 is high relative to the support element 214 and/or at or adjacent to a tidal change.

The surface of the body of tidal water 12 may translate faster than the buoyant element 216 and/or body 230 such that the buoyant element 216 and/or body 230 lags relative to the surface of the body of tidal water 12. In Figure 8, the relative rates of translation of the surface of the body of tidal water 12 and the buoyant element 216 are indicated by Arrow A and Arrow B respectively.

Figure 9 shows the energy harnessing system 210 of Figure 8 after a period of time has elapsed. The level of the body of tidal water 12 is shown at or adjacent to one of high tide and low tide. The body of tidal water 12 may even have entered a slack water period. As such, the rate of translation of the level of the surface of tidal water 12 has decreased.

This is indicated in Figure 9 as Arrow C. The rate of translation may even be or be substantially zero. The buoyant element 216 continues to translate, due to buoyancy or, here due to gravity, and is slowed by the locking means 220 in the braking condition, as indicated by Arrow D. The buoyant element 216 continues to produce electricity, regardless of the level of the body of tidal water 12.

Figure 10 illustrates a fourth embodiment of an energy harnessing system 310, shown in-use in a body of tidal water 12. Features of the fourth embodiment which are similar to the first embodiment have similar reference numerals with the prefix "3" added. The energy harnessing system 310 of the fourth embodiment is similar to the energy harnessing system 10 of the first embodiment, comprising at least one support element 314, at least one buoyant element 316, and at least one electricity generation means 318. The energy harnessing system 310 may further comprise at least one locking means 320, and at least one compartment 334, but any of the above features may be omitted. Detailed description of the common features is omitted for brevity.

The electricity generation means 318 or any part thereof may be positioned in, on or under the buoyant body 330 and/or buoyant element 316, whether partly or fully. For example, the, each or at least one of the generators 336a may be positioned in, enclosed within, encased within, surrounded by, sealed or substantially sealed within the buoyant body 330. This may be instead of or in addition to the, each or at least one generator associated with the support element.

Positioning part of or all of the electricity generation means 318, such as but not limited to a generator 336a thereof, in, on, or under the buoyant body 330 may have any of the following advantages.

The electricity generation means 318 may be easier to access, maintain, repair, replace or service. The risk of damage from lightning may be reduced. The buoyant body 330 may provide weather proofing. The buoyant body 330 may provide a protective shell to the electricity generation means 318. The protective shell may optionally be waterproof or watertight and/or electrically non-conductive. For example, the, each or at least one generator 336a may be housed or contained within at least one said, preferably sealed or sealable, compartment 334. The electricity generation means 318 or part thereof may therefore be beneath the level of the surface of the body of tidal water 12, at least part of the time whilst remaining dry or substantially dry.

The connection means may not need to be movable. For example, if the, each or at least one generator is movable relative to the support element instead, the connection means may be non-movable relative to the support element. The connection means may not be required to or able to rotate around the guiding portion. The connection means may not even need to form a loop. Any of: the connection means, the guiding portion and the receiving conduit may even be omitted entirely, as shown in Figure 10.

Instead of or in addition to the connection means, the electricity generation means 318 may be engageable with the support element 314, directly or indirectly, for example via comprising a first engagement section 340. The support element 314 may comprise a complementary second engagement section 342. The first and/or second engagement sections 340,342 may include at least one wheel, cog, gear, shaft, or any other suitable rotatable part. The first and/or second engagement sections 340,342 may optionally have at least one grip-enhancing feature 344 and/or be textured, although each grip-enhancing feature may be omitted and/or the or each section may be non-textured, such as smooth, may be envisioned. A grip-enhancing feature 344 may comprise at least one of any of the following: a tooth, a protrusion, a groove, a notch, a slit, or any other desirable grip-enhancing feature.

In use, upon the buoyant body 330 rising and falling, the electricity generation means 318 may translate vertically relative to the support element 314. The vertical translation may actuate the first and/or second engagement section 340,342 to rotate, thereby causing the or a said generator 336a to rotate and generate electricity.

In all the above embodiments, the buoyant body or the shell thereof is preferably integrally formed or formed as one bloc. It may alternatively be that the buoyant body and/or the shell may comprise sub-units or modules that are assembleable. Thus, the buoyant body may be modular. The ease of installation and/or manufacture may be increased. Furthermore, the size of the buoyant body may be scalable and/or adjustable.

Although the buoyant body may fully surround the support element, alternatively, the buoyant body may not fully surround or enclose the support element. Thus, an open channel may be provided instead of a through-bore. Said channel may be open at both the upper and lower major surfaces and at least partly along the extent therebetween, also referred to as a longitudinal extent or axial extent of the channel. The channel may comprise a recess, a slit, a slot, or a groove. The channel may extend, at least partly inwards from the or a perimeter wall. The channel may optionally have a width at least equal to a major lateral dimension or cross-section of the support element. This feature may improve the ease of assembly of the system, as the buoyant body may be translated laterally or slotted onto the support element via the channel.

It is therefore possible to provide an energy harnessing system for generating electricity from a body of tidal water. By depending on the fide, the system provides a predictable, rate of generation of electricity. As the turbine is above the water, the ease of access thereto is improved, resulting in easier maintenance, and servicing. Corrosion, erosion and silting of the turbine may even be reduced or prevented. Furthermore, the lockability and releasability of the buoyant element provides energy storage in the form of potential energy or buoyant energy.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

The embodiments described above are provided by way of examples only, and various 25 other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.

Claims

Claims 1 An energy harnessing system for generating electricity from a body of tidal water, the energy harnessing system comprising: a support element suitable for installation in a body of tidal water; a buoyant element which is vertically translatable with respect to the support element in two opposing directions, the buoyant element having a buoyancy which enables flotation at or adjacent to a surface of the said body of tidal water and which forms an artificial tidal habitat; at least one growth promotor associated with the buoyant element configured to promote the growth of a marine organism on the artificial tidal habitat; an electricity generator for generating electricity from the vertical translation of the buoyant element; and a locking means for locking a vertical position of the buoyant element relative to the support element, so that, when the body of tidal water is in a tide-raised condition, the buoyant element is lockable by the locking means and then releasable to fall under gravity thereby driving the electricity generator once the surface of the body of water has lowered relative to the buoyant element, and when the body of tidal water is in a tide-lowered condition, the buoyant element is lockable by the locking means and then releasable to rise due to said buoyancy thereby driving the electricity generator once the surface of the body of water has risen relative to the buoyant element.
2 An energy harnessing system as claimed in claim 1, wherein the growth promotor comprises a surface coating of the buoyant element.
3 An energy harnessing system as claimed in claim 2, wherein the surface coating is a surface-roughness-increasing coating.
4 An energy harnessing system as claimed in any one of the preceding claims, wherein the growth promotor comprises a nutrient source integrally formed with or impregnated into the buoyant element.
5 An energy harnessing system as claimed in any one of the preceding claims, wherein the nutrient source comprises a fertilization system of the buoyancy element.
6 An energy harnessing system as claimed in any one of the preceding claims, wherein the growth promotor comprises at least one artificial marine habitat support structure associated with the buoyancy element.
7. An energy harnessing system as claimed in any one of the preceding claims, further comprising food harvesting equipment for harvesting animal or plant matter from the marine organism, the food harvesting equipment being powerable by the electricity generator.
8. An energy harnessing system as claimed in any one of the preceding claims, wherein the buoyant element comprises a plurality of internal compartments.
9. An energy harnessing system as claimed in claim 8, wherein at least one said internal compartment is sealed.
10. An energy harnessing system as claimed in claim 8 or in claim 9, wherein at least one said internal compartment has a hexagonal cross-section.
11. An energy harnessing system as claimed in claim 10, wherein a plurality of said internal compartments form a hexagonal lattice structure.
12. An energy harnessing system as claimed in any one of claims 8 to 11, wherein at least one said internal compartment contains a buoyancy-providing element.
13. An energy harnessing system as claimed in any one of the preceding claims, wherein the buoyant element comprises recyclable and/or unrecyclable waste.
14. An energy harnessing system as claimed in claim 13, when dependent on any one of claims 7 to 11, wherein said waste is contained within at least one said internal compartment.
15. An energy harnessing system as claimed in any one of claims 13 or claim 14, when dependent on any one of claims 7 to 12, wherein at least one said internal compartment has a wall comprising said waste.
16. An energy harnessing system as claimed in any one of the preceding claims, wherein the buoyant element comprises a through-bore for receiving the support element therethrough such that the support element prevents or inhibits lateral displacement of the buoyant element.
17. An energy harnessing system as claimed in claim 16, wherein the buoyant element comprises at least two contact portions which are simultaneously abuttable against the support element, the at least two contact portions being vertically spaced-apart for inhibiting tilting of the buoyant body relative to the support element.
18. An energy harnessing system as claimed in any one of the preceding claims, wherein the support element comprises any of: a pole, a pylon, and a tower.
19. An energy harnessing system as claimed in any one of the preceding claims, wherein the support element comprises a support tower of an offshore wind turbine.
20. An energy harnessing system as claimed in any one of the preceding claims, wherein the buoyant element has a toroidal body.
21. An energy harnessing system as claimed in any one of the preceding claims, further comprising a connector for coupling the buoyant element to the electricity generator.
22. An energy harnessing system as claimed in any one of the preceding claims, wherein the locking means is in-use in one of: an engaged condition, a disengaged condition, and a braking condition, wherein when the locking means is in the braking condition, a speed of translation of the buoyant element rising due to buoyancy or falling under gravity is reduced for enabling electricity generation to continue during at least part of a slack water period.
23 A method of harnessing energy from a body of tidal water for generating electricity, the method comprising the steps of: a] providing an energy harnessing system as claimed in any one of the preceding claims; b] generating electricity when the buoyant element rises vertically and/or is lowered vertically.
24 A method of extracting energy from a body of tidal water and using said energy to selectably generate electricity, the method comprising the steps of: a] locking a vertical position of a buoyant element when the said body of tidal water is in a tide-raised condition and waiting for a surface of the body of tidal water to fall for storing energy from the body of tidal water as potential energy, or locking a vertical position of the buoyant element in a fide-lowered condition and waiting for a surface of the body of tidal water to rise for storing energy from the body of tidal water as buoyancy energy; b] releasing the buoyant element such that vertical translation of the buoyant element due to gravity or buoyancy drives an electricity generator.A method as claimed in claim 23 or claim 24, wherein the buoyant element is fully submergible below a surface of the body of tidal water.