The present invention relates to an energy storage system for storing energy and generating electricity in an aquatic environment. The present invention also relates to a method of use of such a system.

Consumers expect electrical energy to be available when they need it. Whilst often taken for granted, this requires a reliable balanced electricity grid to which electricity is supplied and from which electricity is drawn.

The electricity grid has voltage and a frequency which must be kept near constant, despite fluctuations in both the demand for electricity and the supply thereof. If the grid is oversupplied or undersupplied with electricity relative to the demand, then the voltage and/or the frequency changes. Damage to devices or even blackouts may ensue if the voltage and/or the frequency changes by more than a specified amount.

Electricity from renewable energy sources is increasingly replacing electricity produced by fossil fuels. Whilst this advantageously results in lower greenhouse gas emissions, the electricity supply from renewable energy sources is inherently more volatile or intermittent than that produced by fossil fuels. As such, the supply and demand mismatch is a growing problem.

One solution to avoid oversupplying the grid is to discard any excess electricity, which is wasteful and inefficient.

Another solution is to provide an energy storage system which stores excess energy. The energy storage system can release stored energy back to the grid, to compensate for any deficit when supply is low relative to demand. Examples of storage systems include chemical batteries, rotating flywheels storing energy kinetically, and gravitational batteries based on pumping water between two reservoirs, one being higher than the other.

However, the current energy storage systems suffer from drawbacks. These drawbacks include high costs, size and scalability, as well as high installation and/or space requirements. Some storage systems are unsuitable for installation or use in certain environments, such as extremes of temperature and/or in an aquatic environment. In chemical batteries, the fire risk is non- negligible, the energy storage and conversion efficiency is affected by the ambient temperature, and sourcing materials can be challenging. Energy dissipation due to friction reduces the efficiency of flywheels. In the case of reservoirs, potential energy is lost when water evaporates due to heat. There are inherent limitations to the underlying technology such as the number of charge and discharge cycles, or the response time to convert stored energy into usable electricity. Examples of environmental concerns include the displacement of populations to install reservoirs, the need to mine for some materials, and the use and/or safe disposal of toxic materials. The present invention seeks to provide a solution to these problems.

According to a first aspect of the invention, there is provided an aquatic energy storage system for selectably storing and releasing energy, the aquatic energy storage system comprising: a buoyant support element having a plurality of internal compartments and waste material; geostationary location means for geostationarily or substantially geostationarily maintaining a predetermined position of the buoyant support element when sited in or on a body of water; a winch mechanism supportable by the buoyant support element and having a flexible elongate element; a mass element connectable to the flexible elongate element; and an electric generator which is connectable to the winch mechanism for generating electricity based on an in-use vertical or substantially vertical translation of the mass element under gravity into the body of water when the winch mechanism unspools the flexible elongate element.

Optionally, at least one said internal compartment may be sealed. Beneficially, at least one said internal compartment may have a hexagonal cross-section. Furthermore, a plurality of said internal compartments may form a hexagonal lattice structure. Packing is optimised.

Preferably, at least one said internal compartment may contain a buoyancy-providing element. The internal compartment or compartments may be at least partly formed of and/or may enclose a material or materials which are buoyant, in other words which have a density less than the body of water in which the energy storage system is sited. The material or materials may or may not comprise waste. The or the plurality of buoyancy-providing elements enable the support element to be sufficiently buoyant to sustain both its own weight and the weight of the mass element when suspended off a bed or bottom of the body of water.

Optionally, the buoyant support element may comprise recyclable waste. Additionally or alternatively, the buoyant support element may comprise unrecyclable or non-recyclable waste. Optionally, the waste may be contained within at least one said internal compartment. Furthermore, the waste may be buoyant. Preferably, at least one said internal compartment may have a wall comprising said waste. Waste is easy and cheap to source. Repurposing waste which may otherwise be disposed of is environmentally friendly.

Furthermore, the waste may comprise plastics. Plastics degrade very slowly, which improves the longevity of the support element.

Advantageously, the buoyant support element may comprise a major upper surface, a major lower surface, and a channel extending therebetween. Beneficially, the channel may be centrally positioned relative to the buoyant support element. A, preferably central, channel enables the mass element to be suspended directly beneath the support element, providing stability. The energy storage system may function with only one mass element without requiring any counterweight.

Additionally, the buoyant support element may have a toroidal body. Furthermore, the buoyant support element may have a square toroidal body or a rectangular toroidal body. A person may walk upon the toroidal body with ease, which may help with maintenance and repairs.

Beneficially, the mass element may have a drag-minimising shape in longitudinal cross-section and/or in lateral cross-section for in-use reducing a vertical or substantially vertical drag force during translation of the mass element and/or a lateral drag force. The efficiency of the energy system is improved as drag is minimised.

Optionally, the mass element may comprise at least one rock. A rock is easy to source. Being a natural, non-toxic element, the environmental impact is minimal, should the mass element break away from the support element and sink to the bottom of the body of water. A rock may also have a rough texture, surface and/or shape which may provide a substrate for the flora and fauna to settle on, thereby improving biodiversity.

Alternatively or additionally, the mass element may comprise waste. As previously mentioned, waste is cheap and easy to source, whilst repurposing waste is environmentally friendly. Waste may be heavy and/or dense, which may be beneficial to increase the mass, and consequently, potential energy which may be stored by the mass element.

Beneficially, the mass element may further comprise a net portion for receiving the at least one rock and/or the waste. The net enables any heavy materials forming a ballast mass to be kept together without requiring any further processing or assembly. There is no requirement to affix the one or more rocks and/or waste or any other weight-providing element to the elongate element. Instead the rocks and/or waste may be loosely held within the net portion. The net portion also advantageously enables the contents within to be removed, exchanged, or replaced.

Advantageously, the mass element may further comprise at least one of a recess and a through- hole, formed in or by the at least one rock and/or the waste for providing a substrate with an increased surface area to support aquatic life. A cavity, recess, or through-hole may provide a shelter for aquatic life, although the drag may potentially be increased as a result. Translation of the mass element and/or currents may accelerate nutrient-rich water through the one or more through-holes. This enhanced flow of water may be advantageous to bring nutrients to sedentary species, such as corals which may have settled and formed colonies on the mass element, by way of example only.

Optionally, the geostationary location means may comprise an anchor. An anchor may be raised, such that the energy storage system may be movable and/or moved to another location. It may be envisioned that the geostationary location means may instead comprise fixed anchoring means and/or foundations which do not permit any movability once in situ.

Beneficially, the aquatic energy storage system may further comprise a motor associated with the winch mechanism for raising the mass element by spooling the flexible elongate element. Advantageously, the winch mechanism may comprise a shaft which may be rotatable by the motor for spooling the flexible elongate element. A motor may automate the process. Furthermore, compared to a manual winch mechanism, an electrically powered winch mechanism may raise a greater weight, although a manual winch may be envisioned instead or in addition to the electrically powered winch.

Optionally, the aquatic energy storage system may further comprise an electric cable connectable to the electric generator and to an onshore energy grid. The cable may be needed to provide a conduit for electricity. The energy storage system may be connectable to the onshore grid only, to both an onshore grid and a source of renewable energy, or to a source of renewable energy only. In the latter case, the cable may be omitted entirely. Although the energy grid is preferably onshore, it may be envisioned that the energy grid may be partly or fully offshore.

According to a second aspect of the invention, there is provided an aquatic energy storage system for selectably storing and releasing energy, the aquatic energy storage system comprising: a buoyant support element having a major upper surface, a major lower surface, a channel extending therebetween and a first centre of gravity; geostationary location means for geostationarily or substantially geostationarily maintaining a predetermined position of the buoyant support element when sited in or on a deep body of water; a winch mechanism supportable by the buoyant support element and having a flexible elongate element, the flexible elongate element being receivable through the channel; a mass element connectable to the flexible elongate element and having a second centre of gravity, wherein in-use the first centre of gravity vertically overlies or overlaps with the second centre of gravity for stabilising the buoyant support element; and an electric generator which is connectable to the winch mechanism for generating electricity based on an in-use vertical or substantially vertical translation of the mass element under gravity into the deep body of water when the winch mechanism unspools the flexible elongate element. The overlapping of the centres of gravity provides stability.

According to a third aspect of the invention, there is provided a method of selectably storing electricity as potential energy in an aquatic environment and generating electricity from said stored potential energy, the method comprising the steps of: a] providing an aquatic energy storage system, preferably in accordance with the first and/or second aspects of the invention; b] selectably converting electricity into potential energy by raising the mass element, and converting stored potential energy into electricity when the flexible elongate element is unspooled such that the mass element is vertically or substantially vertically translated under gravity into a deep body of water. Energy from an electricity grid and/or energy from a renewable energy source, whether excess or non-excess, may be converted into potential energy until electricity is required.

According to a fourth aspect of the invention, there is provided an aquatic energy storage system for selectably storing and releasing energy, the aquatic energy storage system comprising: a buoyant support element submersible below a surface of a body of water; an elongate support element extending from the buoyant support element; a platform element spaced-apart from the buoyant support element and which is at or adjacent to the elongate support element, so as to at least in part mitigate the effect of waves and/or currents on the aquatic energy storage system; geostationary location means for geostationarily or substantially geostationarily maintaining one or a plurality of positions of the buoyant support element when sited in the body of water; a winch mechanism supportable by the platform element and having a flexible elongate element; a mass element connectable to the flexible elongate element; and an electricity generation means which is associated with the winch mechanism for generating electricity based on an in-use vertical or substantially vertical translation of the mass element under gravity into the body of water when the winch mechanism unspools the flexible elongate element; wherein the flexible elongate element extends from, and preferably through, the buoyant support element such that the flexible elongate element and the mass element together form a stabilisation element for stabilising the in-use aquatic energy storage system in a predetermined orientation and for biasing the aquatic energy storage system towards the predetermined orientation when the aquatic energy storage system is displaced therefrom. The flexible elongate element and the mass element are multifunctional. A first function is to provide a mechanism for storage and generation of energy by lowering and raising the mass element, connected to the electricity generation means and winch mechanism by the flexible elongate element. A second function of the flexible elongate element and the mass element is to provide a restoring or stabilising force when the aquatic energy storage system is displaced from a predetermined orientation or equilibrium. This is achieved by the flexible elongate element traversing or passing through the buoyant support element and mass element providing the storage system with a lower centre of gravity.

Beneficially, the flexible elongate element may extend at least partly through the elongate support element. The elongate support element therefore provides protection to the flexible elongate element.

Preferably, the buoyant support element may comprise waste. This provides a second use for materials which would otherwise typically end up in landfill.

Advantageously, the aquatic energy storage system may further comprise a protector element which may be positionable in, at or adjacent to a through-bore or recess of the buoyant support element, so as to prevent or inhibit abrasion damage to the buoyant support element and/or the flexible elongate element. The protector element acts as a buffer between the flexible elongate element and the buoyant support element. This therefore increases the lifespan of both features.

Optionally, the protector element may have a rotatable portion so as to rotate when the in-use flexible elongate element is spooled or unspooled. As the protector element preferably rotates together with the flexible elongate element, the flexible elongate element does not translate or translate as much relative to the protector element. This may decrease friction therebetween.

Additionally or alternatively, the protector element may have a curved surface around which the flexible elongate element is receivable. A curved surface does preferably not comprise a sharp edge which could weaken and/or saw through the flexible elongate element.

Optionally, the aquatic energy storage system may have a plurality of mass elements. A plurality of mass elements increases the total amount of energy that can be stored by the aquatic energy storage system. If the aquatic energy storage system is located in a shallow body of water such that the distance each mass element can travel is restricted, a plurality of mass elements may compensate for this limitation.

Preferably, the aquatic energy storage system may have a plurality of flexible elongate elements. Beneficially, the mass element may be connectable to at least two of the plurality of flexible elongate elements. Thus, a plurality of flexible elongate elements being connected to the same mass element provides redundancy. Furthermore, the weight supported by each flexible elongate element is at least halved, thereby reducing the risk of structural failure of any flexible elongate element. In other words, a limiting factor of the amount of energy that can be stored may be the maximum weight that each individual flexible elongate element can support. Therefore, providing a plurality of flexible elongate elements means that the or each mass element can have a total weight which exceeds the maximum weight that each flexible elongate element can withstand individually. In turn, the greater the total weight, the greater the amount of energy that can be stored.

Advantageously, the aquatic energy storage system may further comprise a spacer element for spacing apart at least two of the plurality of flexible elongate elements from each other. Optionally, the spacer element may be suspendable from at least one of: the buoyant support element, the elongate support element, and the platform element. Preferably, the spacer element may comprise a spacer-platform having a plurality of spaced-apart bores and/or recesses for receiving a flexible elongate element therein. This enables the mass elements connected to the ends of the flexible elongate elements to be spaced apart from each other so as to not abut against each other. Therefore, the mass elements can function, without interfering with another mass element. This may be particularly advantageous if the other mass element is travelling in a different direction and/or at a different speed. Furthermore, the plurality of flexible elongate elements can be received within a same recess or through-bore of the buoyant support element, thereby reducing the number of through-bores or recesses required in the buoyant support element.

Beneficially, the winch mechanism may comprise a spool around which the or a said flexible elongate element is at least partly spoolable. Optionally, a first end of the flexible elongate element may be connectable to the or a said mass element, and a second end of the flexible elongate element is one of: connectable and non-connectable to the spool. Furthermore, the aquatic energy storage system may further comprise a weight to which the second end may be connectable. The second end being connectable to the spool results in the flexible elongate element being attached in use to the spool, thereby reducing the risk of the flexible elongate element and consequently mass element becoming detached from the spool. By being non- connectable, the second end may remain free and/or connectable to a second mass element or other weight. The total size of the spool may be decreased. This may be due to at least a minor extent of the flexible elongate element, but preferably less than the whole extent of the flexible elongate element being wrapped in use around the spool.

Preferably, the winch mechanism may comprise a rotatable shaft. Beneficially, the spool may have an axis of rotation which may be parallel or substantially parallel with the rotatable shaft. Furthermore, the spool may have an axis of rotation which may be non-parallel with the rotatable shaft. Additionally, the axis of rotation may be coaxial or substantially coaxial with the rotatable shaft. Alternatively, the axis of rotation may be perpendicular or substantially perpendicular with the rotatable shaft. Beneficially, the aquatic energy storage system may further comprise a gear mechanism connecting the spool and the rotatable shaft of the electricity generation means, such that rotation of the rotatable shaft rotates the spool. A coaxial alignment provides a simple arrangement which is advantageous in a hostile and/or aquatic environment. Parallel and non parallel arrangements may be more complicated, but beneficially may increase the number of spools accommodated and/or distribute the weight of mass elements connected thereto. This in turn may increase the overall stability of the buoyant support element.

Additionally, a ratio of: the density of the elongate support element over the density of the body of water at or adjacent the surface may be in the range of 0.25 to 1. If the ratio is 1 , the elongate support element may be 50% submerged and 50% above the surface of the body of water. When a wave passes, there may or may not be lift or fall vertical forces imparted on the elongate support element. This may provide an unstable condition for maintaining the 50% position. If the ratio is less than 1 , the elongate support element may have greater stability whilst minimising lift and fall forces acting upon the elongate support element when a wave passes. Advantageously, the aquatic energy storage system may further comprise a dynamic depth- adjustment means for dynamically adjusting the depth of the buoyant support element relative to the surface of the body of water and/or relative to the platform element. As the buoyant support element may compensate for vertical movement of the surface, such as due to tides and/or waves, the absolute vertical movement of the platform element may be reduced or cancelled. This increased vertical stability may be advantageous, for example for enabling aircraft to land upon the platform element and/or reduce motion sickness.

Optionally, the aquatic energy storage system may further comprise a depth-measuring element. It may be disadvantageous for the mass element to reach the floor of the body of water and be supported thereby, as in this situation, the mass element may no longer provide a restoring or stabilising force when the storage system is displaced from the predetermined orientation. Furthermore, the centre of gravity of the storage system may be higher such that the storage system may be more easily displaced from the predetermined orientation. Thus, knowledge of the total distance to the floor of the body of water from the surface and/or from a mass element reduces the risk of the mass element reaching the floor of the body of water. Furthermore, the or the plurality of mass elements may counteract the buoyancy of the buoyant support element. If the or the plurality of mass elements reaches the floor, the buoyant force of the buoyant support element may no longer be opposed or opposed to the same extent. The buoyant support element may therefore rise towards the surface. This may risk damaging or breaking part of the geostationary location means.

Beneficially, at least one of the buoyant support element, elongate support element, geostationary location means, and platform element may form an artificial tidal habitat; and the system may further comprise at least one growth promotor associated with the artificial tidal habitat configured to promote the growth of a marine organism thereon. The energy storage system enables or permits electricity to be stored as potential energy until required. The energy storage system is unaffected by extreme conditions, such that it is usable in most environments and conditions. The conversion of potential energy into electricity is or is substantially instantaneous. Storage and conversion efficiency is independent of the ambient temperature. By being a mechanical gravitational battery rather than a chemical battery, the energy storage system suffers little to no losses in efficiency over its lifespan, regardless of the number of charge and discharge cycles. By being in an aquatic environment, the risk of fire is reduced. Any fire which were to break out would be isolated and unlikely to cause any damage to neighbouring structures. Upon the buoyant support element sustaining damage, the plurality of compartments limits any influx of water, such that the buoyant support element remains functional. The buoyant support element may even be modular for scalability, and at least two said compartments may correspond or belong to two distinct modules. The mass element may preferably be underwater and out of sight, preferably at all times. Furthermore, the buoyant support element may be at least partly underwater and out of sight, preferably at all times. As such, the buoyant support element may be or be substantially out of sight and/or invisible, which may be visually appealing. As the buoyant support element and/or the mass element may comprise waste material, the energy storage system may have a low, or even a positive environmental impact. The provision of a growth promotor in association with the buoyant support element of an aquatic energy storage system allows for the system to be used in an agricultural context, via farming of marine plant or animal lift. In other words, the system may be used for aquaculture. 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.

Optionally the growth promotor may comprise a surface coating of the buoyant support element, elongate support element, geostationary location means, or platform element.

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 support element, elongate support element, geostationary location means, or platform element.

The nutrient source may comprise a fertilization system of the buoyant support element, elongate support element, geostationary location means, or platform element.

Optionally, the growth promotor may comprise at least one artificial marine habitat support structure associated with the buoyant support element, elongate support element, geostationary location means, or platform 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 support element, elongate support element, geostationary location means, or platform element for this purpose.

The aquatic energy storage 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 generation means. Harvesting of food from the buoyant element may be improved by harvesting equipment, which can be beneficially powered without the need for an external power source due to the presence of the electricity generation means.

According to a fifth aspect of the invention, there is provided a method of stabilising an aquatic energy storage system, the method comprising the steps of: a] providing an aquatic energy storage system, preferably in accordance with the fourth aspect of the invention, in an assembled condition and wherein the aquatic energy storage system has a predetermined orientation in situ; and b] when the aquatic energy storage system is displaced from the predetermined orientation, the stabilisation element biases the aquatic energy storage system back towards the predetermined orientation. The method provides a way of stabilising the aquatic energy storage system and restoring or biasing the storage system back towards the predetermined orientation or equilibrium position, when displaced therefrom.

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 side view of an embodiment of an aquatic energy storage system, in accordance with the first aspect of the invention, with a channel and part of a flexible elongate element received therethrough indicated as dashed lines; and

Figure 2 shows a perspective view of the aquatic energy storage system of Figure 1 , with part of the geostationary location means and the mass element omitted for clarity, and with a part cut-away portion showing an internal hexagonal lattice structure;

Figure 2A illustrates a perspective view of a further embodiment of an aquatic energy storage system, with a mass element and part of a geostationary location means omitted for clarity;

Figure 3 depicts a side cut away view of a further embodiment of an aquatic energy storage system, in accordance with the fourth aspect of the invention;

Figure 4a shows a top plan view of the aquatic energy storage system of Figure 3;

Figure 4b shows a top plan view of the aquatic energy storage system of Figure 3 with an alternative embodiment of a winch mechanism;

Figure 5 illustrates a perspective top view of a further embodiment of an aquatic energy storage system in accordance with the fourth aspect of the invention with the geostationary location means, the buoyant support elements and the mass elements omitted for clarity; and

Figure 6 shows a perspective bottom view of the aquatic energy storage system of Figure 5, with the platform elements and geostationary location means omitted for clarity.

Referring to Figures 1 and 2, there is shown an energy storage system indicated generally at 10 for selectably storing and releasing energy. The energy storage system 10 is positioned at least partly in a body of water 12. As such, the energy storage system 10 may be referred to as an aquatic energy storage system 10. In Figures 1 and 2, the surface of body of water 12 is indicated as waves. The body of water 12 may be freshwater, such as a reservoir, a lake, or any other suitable body of freshwater. Alternatively, the body of water 12 may be saltwater, such as a sea or an ocean. In the case of saltwater, the energy storage system 10 may be referred to as a marine energy storage system 10. In all cases, the body of water 12 is preferably deep, such that the energy storage system 10 is sited in or on a deep body of water 12, but this feature may be omitted.

The energy storage system 10 comprises a support element 14, a geostationary location means 16, a winch mechanism 18, a mass element 20 and an electricity generation means 22. The energy storage system 10 further comprises a motor 24 and a locking means 26, but either or both features may be omitted.

The support element or support 14 in-use provides or functions as a support or a platform. The support element 14 may be referred to as an island. Preferably, the support element 14 is buoyant such that it floats in or on the body of water 12, but a non-buoyant support element may be envisioned. As shown, the support element 14 preferably floats on, at or adjacent to a surface of the body of water 12. The support element 14 must be sufficiently buoyant to support itself and the mass element 20 when the mass element 20 is suspended in-use.

The support element 14 may comprise waste and/or non-waste. Waste is understood to be material which has had a prior use, whilst non-waste has had no prior use. Typical non-waste materials may include plastics, metal, concrete, cement, wood, water, fluids, liquids, any other suitable material, or combination thereof. Waste material may comprise any or any combination of: demolition material, metal, coal, ash, soil, debris, gravel, rocks, building waste, plastics, concrete, cement, water, fluids, liquids, wood, or any other suitable material. The waste and/or non-waste are preferably buoyant, but this feature may be omitted. 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 support element 14 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 support element 14 comprises plastics. Recycled plastics may be formed or moulded into a desirable shape or structure. The support element 14 comprises a support body 28 and at least one channel 30, although the latter feature may be omitted.

The support body 28 comprises a first major surface 32a, a second major surface 32b, and at least one perimeter wall 34. Preferably, at least one of, and here both the first and second major surfaces 32a, 32b are planar and parallel with each other but non-planar and/or non-parallel may be envisioned. The first major surface 32a is preferably an upper surface in use. The first major surface 32a is preferably above the surface of the body of water at all times, but this feature may be omitted. Similarly, the second major surface 32b is preferably a lower surface in use. The second major surface 32b may be below, at, on, or above the surface of the water.

The perimeter wall 34 extends between the first major surface 32a, and the second major surface 32b and is preferably contiguous to one or both surfaces. As shown in Figure 2, the perimeter wall 34 is circular in plan view, although non-circular may be envisioned, such as curved, non- curved, part curved, linear, non-linear, an elliptical, oval, hydrodynamically or aerodynamically shaped, polygonal, whether irregular or regular, such as square, rectangular, whether chamfered or non-chamfered, hexagonal, octagonal, or any other desirable shape may be envisioned. The support body 28 may be a prism, such as a rectangular or square prism. The support body 28 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 support body 28 also has a centre of gravity, hereon referred to as a first centre of gravity for clarity. Preferably, the support body 28 also has a mass which is or is substantially uniformly distributed. This advantageously results in the first centre of gravity being positioned or located centrally or substantially centrally relative to the buoyant support element 14 and/or the support body 28. The support element 14 is preferably monolithic.

The support body 28 may have a major dimension and/or a minor dimension. Preferably, a major dimension and/or a minor dimension of the support element 14 is at least 50 metres in length, and more preferably at least 100 metres in length, although less than 50 metres may be envisioned. Most preferably, a major dimension and/or a minor dimension of the support body 28 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 support body 28, but this need not be the case. The support body 28 may provide a shelter and/or a substrate for fauna and/or flora to settle in, on, or under. In other words, the support body 28 may provide a habitat and/or may be wildlife-friendly. By being buoyant, the support body 28 is or is substantially at a constant depth in the water column, whether at the surface or away therefrom. This may be beneficial to species which have a narrow ecological niche, and/or which are sensitive to any of temperature, light, and pressure. Optionally, the support body 28 or part thereof, such as any of the upper surface 32a, the lower surface 32b, and the perimeter wall 34 may comprise a wildlife-friendly coating and/or surface texture which may encourage or enhance wildlife colonisation.

The channel 30 connects or meets with at least one of, and preferably both, the first major surface 32a, and the second major surface 32b, extending therebetween. The channel 30 is open at the first major surface 32a and at the second major surface 32b. As shown, the channel 30 is preferably closable or closed along at least part of the extent between the major surfaces 32a, 32b, also referred to as a longitudinal extent. In other words, the channel 30 is preferably entirely surrounded or enclosed by the support body 28. In this case, the channel 30 may be referred to as a through-hole, a bore, or a through-bore. The channel 30 is preferably suitably dimensioned and shaped to receive part of the winch mechanism 18 therein or therethrough. In other words, the support element 14 preferably surrounds or encloses part of the winch mechanism 18. In the present embodiment, the channel 30 is circular in lateral cross-section as shown in Figure 2, but non-circular may be envisioned. A wall or walls 36 defining the channel 30, and indicated in dashed lines in Figure 1, is or is substantially planar or linear in longitudinal and/or axial cross- section, although non-planar or non-linear may be envisioned, such as curved, part-curved, polygonal, whether regular, irregular, or chamfered. The channel 30 is preferably centrally positioned relative to the buoyant support element 14 and/or the support body 28, for stability, but offset therefrom may be an option. As such, the support element 14 may have a toroidal body. In other words, the support element 14 and/or the support body 28 may therefore be a, preferably coaxial, annulus in plan view. In other words, the support body 28 may be an annular cylinder, or a toroid.

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 hole or 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. In the preferred embodiment, the support element 14 has a square toroidal body or a rectangular toroidal body.

The support element 14 and in more preferably, the support body 28 may optionally further comprise at least one, and here a plurality of compartments 38, also referred to as pockets, or cells, as shown in Figure 2, but no compartments may be envisioned. At least one said compartment 38 may be internal but this need not be the case. At least one, and preferably all said compartments 38 are sealable or sealed, although all or at least one of the internal compartments may not necessarily be sealed. In other words, one or more compartments may be open.

Each internal compartment 38 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 38 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. For example, at least one internal compartment may be a sphere, a cube, a rectangle, a regular or irregular polyhedron, or a prism. The internal compartments 38 are all identical to each other but it may be envisioned that the support body 28 may comprise at least two differently shaped and/or differently sized internal compartments. A plurality of internal compartments 38 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 38 having the same cross-section. Additionally or alternatively, the lattice structure or foam may comprise at least two internal compartments 38 which have a different cross-section. At least two compartments 38 may be adjacent to each other and/or may share a wall. The, each or at least one compartment 38 may extend from or substantially from an in-use upper surface to an in-use lower surface of the support element 14, here the first major surface 32a, and the second major surface 32b, as shown in Figure 1 , but this feature may be omitted. In other words, there is preferably one layer of compartments 38, but any number of layers, including at least two, may be envisioned.

Additionally or alternatively, the, each or at least one compartment 38 may extend from or substantially from an in-use side surface to a further in-use side surface of the support body 28. In the case of a circular support body 28 comprising a single side or perimeter wall, one or more compartments 38 may extend along part of a chord or a diameter of the support body 28, 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 support body 28.

In the illustrated embodiment, at least one, and preferably all said internal compartments 38 have a hexagonal cross-section. An example of such hexagonal compartments 38 is shown in Figure 2 through a part cut-away portion. A plurality of said internal compartments 38 may form a hexagonal lattice, such that the support body 28 may comprise a hexagonal lattice structure or honeycomb structure. Such a structure provides an optimised packing of the compartments 38 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 38 may contain and/or be filled with a buoyancy-providing element, portion, material, fluid or chemical. 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, and/or one or more compounds. The gas or gaseous mix may comprise any of: Oxygen, Carbon Dioxide, Nitrogen, Helium, any other suitable gas, or combination of gases. Furthermore, at least one said internal compartment 38 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 38. Preferably, if the buoyancy-providing elements are distributed amongst at least two internal compartments 38, said plurality of compartments 38 are preferably distributed across the support body 28, although this feature may be omitted.

Segmentation or compartmentalisation and distribution of the buoyancy-providing elements provides a more uniform density across the support element 14. This feature is advantageous, should the support body 28 sustain any damage. For example, if part of the support body 28 is broken off such that an opening is created into one or a subset of compartments 38, any influx of water is restricted to that compartment or subset of compartments 38. The average density of the whole support body 28 is unaffected or substantially unaffected. Thus, the support element 14 remains functional or substantially functional despite sustaining damage. Smaller compartments 38 are advantageous to restrict and limit the effect of any damage. However, larger compartments may be easier to manufacture.

In comparison, upon sustaining damage, a single-compartment support body 28 may fill up with water. Such a support body 28 may sink, thereby having reduced functionality or no longer being functional.

Optionally, it may even be envisioned that the or at least one said compartment 38 may be open or have at least one opening, access, aperture, perforation, gap on or in an in-use lower surface of the support body 28, here the second major surface 32b. Such a compartment 38 may be otherwise watertight or airtight, and/or may be filled with or contain a buoyancy-providing element, such as but not limited to air. In-use, the surface of the body of water may seal the at least one opening, preventing or inhibiting the buoyancy-providing element from escaping from the or each compartment 38. Simultaneously, the buoyancy-providing element opposes, inhibits, or prevents entry of water into the or each such compartment 38. The buoyancy-providing element may or may not be compressible and/or compressed. The support body 28 or at least one compartment 38 thereof may be a caisson, and more preferably a compressed air caisson.

The geostationary location means 16 in-use maintains or substantially maintains a predetermined latitudinal and/or longitudinal position of the support element 14 geostationarily or substantially geostationarily. In other words, geostationary location means 16 may prevent or inhibit drift of the support element 14. The geostationary location means 16 may be referred to as a geolocator, geostationary location assembly, or mechanism. The geostationary location means 16 comprises at least one and preferably three, anchoring elements, assemblies or mechanisms 40, as shown. The or each anchoring element 40 may connect or engage with a bed of the body of water. The or each anchoring element 40 may comprise at least one weight or anchor 42a, and at least one tether 42b connecting the anchor 42a to the support element 14.

The winch mechanism 18 in-use enables the mass element 20 to be winched, raised, or hoisted towards the support body 28 and/or away from the bed of the body of water 12. The winch mechanism 18 is supported or supportable by the support element 14. The winch mechanism 18 may be positioned on, in, under, or in any combination of the above relative to the support body 28. The winch mechanism 18 has an elongate element 44 and a winch 46.

The elongate element, portion, or connector 44 extends at least between the support element 14 and the mass element 20. The elongate element 44 is preferably flexible, but non-flexible or part flexible may be envisioned. The elongate element 44 comprises at least one chain, cable, or rope, or combination thereof, although any other elongate element may be envisioned. The elongate element 44 in-use extends through or is receivable through the channel 30. The elongate element 44 has a first end, connected or connectable to the winch 46 and a second end, connected or connectable to the mass element 20. At the second end, the elongate element 44 further comprises an engagement means, not shown, for engaging with the mass element 20.

The engagement means, mechanism or portion may comprise at least one of any of the following: a hook, a loop, a bolt, or any other suitable type of engagement means. The engagement means is preferably separably connectable with the mass element 20 but non-separably engageable therewith may be envisioned.

The winch 46 may be referred to as a hoist. The winch 46 comprises at least a drum 48 and optionally a winch body, not shown, for supporting the drum 48. The drum 48, also referred to as a spool, enables the elongate element 44 to be spoolable, wrappable or wrapped therearound.

Preferably, the winch 46 also comprises a drum-rotation means or mechanism 50 for rotating the drum 48. In the present embodiment, the drum-rotation means 50 comprises a drum-engagement means 52 and the said motor 24 but either or both features may be omitted. As such, the motor 24 is associated with the winch mechanism 18 for raising the mass element 20 by spooling the elongate element 44.

The drum-engagement means or mechanism 52 comprises a shaft, however this feature may be omitted. In addition to or instead of the shaft, the drum-engagement means 52 may comprise gearings and bearings, not shown, for example. The shaft extends from the motor 24 to the drum 48 and may connect with or extend through the drum axle or axis. Here, the shaft is preferably rotationally locked with the drum 48. Thus, in-use the motor 24 may rotate the drum 48 by rotating the drum-engagement means 52, which is here preferably the shaft.

The winch mechanism 18 may also comprise the said locking means 26, but this feature may be omitted. The locking means 26 may also be referred to as a locking device, locking mechanism, locking apparatus, or lock. The locking means 26 in-use prevents or inhibits the mass element 20 from being translatable in at least one direction, and more preferably in both directions. In other words, the locking means 26 may prevent the mass element 20 from being raisable and/or lowerable or in free-fall. The locking means 26 may even comprise a braking mechanism which may be used to control and/or modify the velocity of translation of the mass element 20. In turn, the generation of electricity may be continuous or substantially continuous over a period of time. In other words, the electricity generation may be smoothed. The locking means 26 may comprise a clamping mechanism or clamp. The locking means 26 may, in-use, act upon any part or parts of the winch mechanism 18. In particular, the locking means 26 may lock any of: the motor 24, the drum-engagement means 52, the shaft, a gearing, a bearing, the drum, the elongate element 44, or any combination thereof.

The mass element, mass portion, or mass 20 is in-use translatable, preferably vertically or substantially vertically, to store or release energy stored as potential energy. The mass element 20 has a centre of gravity, referred to as a second centre of gravity for clarity. The mass element 20 comprises non-buoyant materials and is connected to the elongate element 44. In the present embodiment, the mass element 20 comprises at least one, and preferably a plurality of weights or weight elements 54. Preferably, as potential energy is a function of mass, the or each weight 54 has the greatest mass possible. The density or mass for a given volume of the or each weight 54 is also as high as possible, to reduce drag due to displacement of a volume of water by the mass element 20. This may increase efficiency of the storage system 10. The or each weight 54 may be naturally formed and/or non-naturally formed. In other words, the or each weight 54 may be man-made or artificial. The or each weight 54 may comprise a, preferably naturally occurring, aggregate of minerals or mineraloids and/or non-minerals, such as organic matter. The aggregate is solid but non-solid or partially solid may be envisioned. In the preferred embodiment, the or each weight 54 preferably comprises a rock, but the, each or at least one weight may comprise waste, and/or non waste in addition to or instead of the rock. As such, the mass element 20 preferably comprises at least one, and more preferably at least two rocks.

Waste may have had a prior use whilst non-waste preferably has not had a prior use. Waste and/or non waste may comprise any of: metals, cement, concrete, plastics, ceramics, sand, gravel, building material, debris, demolition material, any other suitable material, or any combination thereof. Metals may include scrap iron, aluminium, steel, or any other suitable material.

The, each, or at least one weight 54 may be regular in shape, but non-regular is preferred. Examples of regular shapes include but are not limited to spheres, discs, cylinders, prisms, cuboids or any other suitable shape. Furthermore, the, at least one, or each weight 54 may optionally have a textured, rough or non-smooth surface.

The mass element 20 may optionally have a drag-minimising shape in lateral cross-section. This may be advantageous for reducing a lateral drag force acting upon the mass element 20, for instance due to currents and/or during storms. This also minimises the risk of the mass element 20 moving or translating laterally and accidentally knocking, damaging, or breaking one or more of the anchoring elements 40.

Additionally or alternatively, the mass element 20 may optionally have a drag-minimising shape in longitudinal cross-section for reducing a drag force when the in-use mass element 20 is translating vertically, substantially vertically and/or towards or away from the support element 14. This reduces the drag experienced when the mass element 20 is translating. In turn, the efficiency of the energy storage system 10 is improved. The mass element 20 may preferably have a circular lateral and/or longitudinal cross-section.

The mass element 20 may comprise a net portion, net, or net-like element 56, although this feature may be omitted. The net 56 may receive, surround, enclose and/or lift the at least one weight 54. As there are preferably one or more rocks and/or waste, the net portion 56 may receive the or the plurality of rocks and/or the waste. Furthermore, the net portion 56 may provide a means to engage or connect the at least one weight 54 to the elongate element 44. The mass element 20 may even comprise a plurality of weights connected or connectable to the elongate element 44 which may or may not be spaced-apart from each other. Additionally or alternatively, the mass element 20 may comprise a plurality of net portions 56. These features may enable the total mass supported, and therefore potential energy stored, to be modular, adjustable or selectable.

The mass element 20 may optionally comprise at least one of a recess and a through-hole, or a plurality of either or both. The at least one recess and/or at least one through-hole may be formed in, between and/or by the or the plurality of weights 54. Said rocks and/or waste, when piled together, may provide the at least one gap, recess, or through-hole. More preferably each recess and/or through-hole may be formed in and/or by the at least one rock and/or waste. By having a recess or through-hole, the weight or weights 54 provide a substrate with an increased surface area to shelter and/or support aquatic life. Any weight 54 may optionally have a textured surface, which may further improve the substrate for flora and fauna to settle in or upon. Thus, the mass element 20 is environmentally friendlier and may enhance biodiversity, particularly compared to a regularly shaped and/or smooth surfaced mass element, which may have no gaps or recesses.

Furthermore, the raising and the lowering of the mass element 20 in use may optionally accelerate water flow in any recess and/or through any gap or through-hole. This in turn may remove stagnant water, debris, biological waste and/or bring nutrients to sedentary filter feeders, such as corals, sponges, and anemones, by way of example only.

The electricity generation means or mechanism 22 comprises an electric or electricity generator, not shown. The electricity generator is preferably a dynamo electric generator, but a non-dynamo electric generator may be envisioned, such as an alternator, or any other suitable type of electric generator. The electricity generator is connectable or connected to the winch mechanism 18. The electricity generation means 22, or part thereof, is positioned on the support element 14 as shown but within or under the support element may be envisioned. If within, the support element 14 may have a second function of protecting the electricity generation means 22 or part thereof, for example from the elements. Similarly, the winch mechanism 18 may be partly or fully enclosed within or be positioned under the support element 14, instead of being positioned on an upper surface thereof.

The energy storage system 10 preferably also comprises at least one electric cable, not shown, but this feature may be omitted. The or each electric cable provides a conduit for electricity. The or each electric cable may be connected or connectable to an onshore electricity grid, to provide electricity thereto and/or draw electricity therefrom. Preferably, the electric cable is connectable, at a first end of the cable, to the onshore energy grid. At the second or other end of the cable, the electric cable may be connectable to the electricity generation means 22. This enables the energy storage system 10 to provide electricity from the electricity generation means 22 or at least a generator thereof to the onshore energy grid.

Alternatively, the second end of the cable may be connectable to the motor 24 for providing a conduit for electricity from the onshore energy grid to power the motor 24 of the energy storage system 10.

Preferably, the cable is connectable to both the motor 24 and the electricity generation means 22.

In use, the energy storage system 10 may need to be installed in position. A location in a, preferably deep, body of water is selected, although shallow water may be an option. The energy storage system 10 provided as a kit of parts. The energy storage system 10 may need to be transported or towed into position, particularly if provided as a kit and/or in a partly or fully disassembled condition.

If not already done, any or all the following steps are undertaken, in any order.

The electricity generation means 22 and the winch mechanism 18 are connected to or engaged with the upper surface 32a of the support body 28.

Preferably, the drum 48 is positioned at or adjacent to, and as shown, directly above the or a said channel 30. The drum-engagement means 52, which is here a shaft, is connectable or connected to the motor 24, as a motor 24 is preferably provided. The motor 24 is preferably positioned on one side of the channel 30 but above, below or around may be envisioned. The drum-engagement means 52 extends from the motor 24 to the drum 48, preferably horizontally or substantially horizontally. Preferably, the drum-engagement means 52 extends beyond the drum 48 and is connectable or connected to the electricity generation means 22. Thus the electric generator is connectable, and here, connected, to the winch mechanism 18.

The second end of the elongate element 44 is inserted into the channel 30 such that the elongate element 44 is received in and passes through the support element 14. The first end of the elongate element 44 is connected to the drum 48.

If required and if not already done, the mass element 20 is assembled and connected to the second end of the elongate element 44. In the present embodiment, assembly involves filling the net 56 with weights 54, here at least one rock and/or waste. The mass element 20 is lowered into the water. Once assembled, the first centre of gravity vertically overlies or overlaps with the second centre of gravity of the mass element 20. This provides greater stability to the support element 14. As the first and second centres of gravity are preferably centrally positioned, this further reduces the risk of the support element 14 capsizing.

If not integrally formed therewith, the geostationary location means 16 is connected to the support element 14 at one end. The geostationary location means 16 is made to engage with the bed of the body of water 12 at the other end.

If provided, the electric cable is connected to the onshore electricity grid at one end. The other end of the cable is connected to either or, preferably, both the electricity generation means 22 and the winch mechanism 18.

Once assembled, the energy storage system 10 is ready for use to selectably store and generate electricity.

The mass element 20 may sit on the floor bed or be suspended by the elongate element 44. When required, the motor 24 is energised or powered by electricity. Said electricity may originate from the onshore electricity grid, and be carried via the electric cable. Furthermore, said electricity may be excess electricity, but this need not be the case. Additionally or alternatively, the electricity may be provided from another source, such as a renewable energy source.

Once energised, the motor 24 causes the drum-engagement means 52, which is here the shaft, to rotate. As the shaft is phase-locked or rotationally locked with the drum 48, the drum 48 rotates with the shaft. The elongate element 44 is spooled, in other words, wrapped around the rotating drum 48 and/or around the rotatable shaft.

The second end of the elongate element 44 rises, and pulls or drags the mass element 20 vertically or substantially vertically towards the support element 14. Thus, the motor 24 associated with the winch mechanism 18 raises the mass element 20 by spooling the elongate element 44. The angular velocity of the drum 48 may or may not be selectable. Electric energy is thereby converted into potential energy.

If provided with a locking means 26, the locking means 26 may be engaged to lock a vertical position of the mass element 20 relative to the support element 14. The vertical position of the mass element 20 is locked until electricity generation is required or until the potential energy needs to be increased further, at which point the locking means 26 may need to be disengaged.

To generate electricity, the mass element 20 is allowed to fall under gravity. The drum- engagement means 52 of the winch mechanism 18, connected to the electricity generator, causes the electricity generator to rotate and thereby generate electricity. Thus, electricity is generated, based on a vertical or substantially vertical translation of the mass element 20 under gravity into the body of water 12 when the winch mechanism 18 unspools the elongate element 44.

In other words, a method of selectably storing electricity as potential energy in an aquatic environment and generating electricity from said stored potential energy is provided. The method comprises the steps of: a] providing an aquatic energy storage system 10; and b] selectably converting electricity into potential energy by raising the mass element 20, and converting stored potential energy into electricity when the, preferably flexible, elongate element 44 is unspooled such that the mass element 20 is vertically translated or substantially vertically translated under gravity into a body of water 12.

In yet again other words, a method of stabilising a frequency of an electricity grid by selectably storing excess energy as potential energy in an aquatic environment and generating electricity from the said stored potential energy is provided.

It will be apparent that the provision of a buoyant support element or buoyant support 14’ in a body of water may provide a suitable structure for many additional uses in addition to energy storage. The buoyant support element 14’ is at or adjacent to the surface of the body of tidal water 12. This means that, in most scenarios, the buoyant support element 14’ is partially submerged. This could allow the buoyant support element 14’ to act as a marine habitat. This permits the use of the buoyant support element 14’ for farming or other agricultural projects, as the buoyant support element 14’ 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 2A, at least one surface of the support body 28’, and most preferably the underwater lower major surface 32b’ 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 32b’ 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 support body 28’, or which can be applied to plants attached thereto via a fertilization system. Features of this embodiment which are similar to the first embodiment have similar reference numerals with an apostrophe added as suffix. In Figure 2A, a mass element or mass, and part of a geostationary location means or assembly are not shown, for clarity, but any of these features may be omitted entirely and/or a plurality may be provided, as required. Although omitted in this embodiment, it may easily be envisioned that an elongate support element or elongate support and/or a platform element or platform may be provided in this embodiment. Optionally the mass element and the or a flexible elongate element or connector may together form a stabilisation element, assembly or mechanism for stabilising the aquatic energy storage system.

It will be appreciated that the artificial tidal habitat and growth promotor may be positioned on any part of the aquatic energy storage system 10’, in this embodiment or in any other embodiment, including the buoyant support element 14’, the geostationary location means 16’, a platform element of the system and/or elongate support element.

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 32c’ which is more biocompatible might be considered to be a growth promotor, which could be applied to the support body 28’. Alternatively, some topological features of the support body 28’ itself could be considered.

A more preferred embodiment, however, given the occlusion of the lower major surface 32b’ of the support body 28’ from the sun, would be to configure the buoyant support element 14’ 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 support body 28’ has a sufficient surface roughness to permit the animals to cling thereto. Additionally or alternatively, the buoyant support element 14’ 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 storage 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 support body 28’, without the need to provide an additional power source. A growth promoter and/or food harvesting equipment may be provided with any of the embodiments described herein.

Referring now to Figure 3, there is a shown a second embodiment of an aquatic energy storage system 110 for selectably storing and releasing energy. Features of the second embodiment which are similar to the first embodiment have similar reference numerals with the prefix “1” added.

The second embodiment of the aquatic energy storage system 110 is similar to the first embodiment, having similar buoyant support element or buoyant support 114; geostationary location means, assembly or geolocator 116; a winch mechanism 118 having at least one flexible elongate element or connector 144, at least one mass element or mass 120 connectable to at least one flexible elongate element 144; an electricity generation means or mechanism 122, and optionally locking means or lock, and a motor 124. Detailed description of the common features is omitted for brevity.

Similarly to the first embodiment, the buoyant support element 114 of the second embodiment may optionally comprise waste and/or compartments. The waste may comprise any of: recycled, recyclable, and non-recyclable waste. The waste may comprise plastics, but non-plastic may additionally or alternatively be envisioned. Detailed description of common features of the waste and compartments is omitted for brevity.

The buoyant support element 114 preferably has at least a major portion or support body 128 and, as shown, at least one minor portion 129, but the or each minor portion may be omitted.

As shown in Figure 3, the minor portion 129 extends from the major portion 128, preferably in a generally vertical direction and/or towards the surface in use, but this feature may be omitted. Such a buoyant support element 114 is therefore bottom heavy and/or the centre of gravity of the buoyant support element 114 is lowered, which may increase the stability of the buoyant support element 114. The major portion 128 and the minor portion 129 have a circular or substantially circular longitudinal and/or lateral cross-section but either or both may have a non-circular longitudinal and/or lateral cross-section. In other words, the minor portion and the major portion are preferably cylindrical, and more preferably coaxially cylindrical.

Optionally, the major portion may have a greater density than the minor portion. Alternatively or additionally, the major portion may have a variable density along its longitudinal extent, such that one part thereof, preferably, the in-use lower part, may be denser, than an in-use upper part of the major portion. This results in a lower centre of gravity to the buoyant support element, which in turn provides greater stability. For example the buoyant support element may be at least partly hollow and filled with at least one liquid and/or at least one solid which, under gravity, sinks to the lowest part of the buoyant support element. A suitable liquid may include water, by way of example only. The remainder of the buoyant support element may be filled with a less dense solid and/or fluid. The solid may include plastics for example. The fluid may include air, helium, or any other fluid having a density lower than the surrounding body of water.

Similar to the first embodiment, the buoyant support element 114 also comprises at least one channel, through-bore, or recess 130 for receiving the, at least one or all flexible elongate elements 144 therethrough. The through-bore or recess 130 extends through at least one of the major portion and the minor portion. Preferably, only one through-bore 130 is provided. The through-bore 130 extends axially through the buoyant support element 114. The through-bore 130 is preferably also centrally positioned relative to at least one of: the major portion and the minor portion.

The body of water 12 at or adjacent the surface has a density. Furthermore, the elongate support element or elongate support 158 has an average density. Preferably, a value of the ratio of the density of the elongate support element 158 over the density of the water at the surface of the body of water is in the range of 0.25 to 1.0, although less than 0.25 or above 1.0 may be envisioned. The ratio may be referred to as a relative density or a specific gravity. More preferably, the value of the ratio is between 0.7 to 1.0, and most preferably is between 0.75 and 1.0. Thus, in the second embodiment, the elongate support element 158 is at least partly submerged, and is more preferably 50% or about 50% submerged. It may alternatively be envisioned that the elongate support element may be fully submerged, fully emerged or any proportion between 0% and 100% of the elongate support element, such as 1%, 10%, 20%, 25%, 30%, 60%, 75%, or any other proportion may extend above the surface of the body of water 12. The proportion may even be variable.

The buoyant support element 114 also has an average density. Preferably, the density of the buoyant support element 114 is such that, in isolation, the buoyant support element 114 may float at or adjacent the surface. Additionally, the density of the buoyant support element 114 may be such that, when the storage system 110 is assembled and in use, it is submerged but simultaneously able to support any or any combination of: the, all or at least one platform element or platform 160; the, all or at least one elongate support element 158; the, all or at least one flexible elongate element; the, all or at least one mass element or mass 120, any other feature provided as part of the aquatic energy storage system 110, and any structure supported by the aquatic energy storage system 110. Most preferably, the density of the buoyant support element 114 is such that in-use, the platform element 160 and/or the elongate support element 158 are at least partly above the surface. The elongate support element 158 may provide some additional buoyancy. This may help maintain stability at or adjacent the 50% submerged position of the elongate support element 158.

The geostationary location means 116 of the second embodiment enables the storage system 110 to be geostationarily or substantially geostationarily by maintaining one or a plurality of positions of the buoyant support element 114 when sited in the body of water 12. This is preferably because fewer than three anchoring elements, assemblies or mechanisms 140 are provided, although three or more anchoring elements may be provided. Alternatively, the anchoring elements may provide some slack. In either case, the storage system 110 may move freely in a constrained area. In the first embodiment, on the other hand, only one or substantially one position could be maintained due to having three anchoring elements 40.

Similarly to the first embodiment, the or each mass element 120 of the second embodiment may optionally comprise waste and/or a net. Detailed description of common features is omitted for brevity. The or each mass element 120 is preferably suspendable or in-use suspended at all times. In other words, the or each mass element 120 is preferably non-storable on the floor of the body of water 12.

In the second embodiment, the aquatic energy storage system 110 further comprises an elongate support element 158, and a platform element 160, although a plurality of either or both may be provided.

The elongate support element 158 extends or is extendable from the buoyant support element 114. The elongate support element 158 in-use supports and/or spaced-apart the platform element 160 from the buoyant support element 114. The elongate support element 158 may be referred to as a pylon or a stilt. The elongate support element 158 has a longitudinal extent and a lateral extent. In transverse or lateral cross-section, the elongate support element 158 is preferably circular or substantially circular, but non-circular may be an option. A circular cross-section may be more hydrodynamic than a non-circular shape, thereby reducing drag forces from any of: wind and/or the body of water 12 acting upon the storage system 110. The elongate support element 158 is preferably at least partly hollow, but non hollow is an option. In other words, the elongate support element 158 has at least one through-bore 130 extending, preferably axially and/or centrally, through the elongate support element 158, but this feature may be omitted. The elongate support element 158 may have buoyancy. Said buoyancy may be variable or alterable.

The platform element or platform 160 is spaced-apart horizontally and/or vertically from the buoyant support element 114. The platform element 160 is at or adjacent to the elongate support element 158. More preferably, the platform element 160 in-use overlaps, overlies, or is generally vertically spaced apart above the buoyant support element 114. The platform element 160 in-use is preferably at least partly, and more preferably fully above the surface of the body of water 12. The shape of the elongate support element 158 and/or the positioning of the platform element 160 relative to the buoyant support element 114 at least in part mitigate the effect of waves and/or currents on the aquatic energy storage system 110. The platform element 160 may optionally provide a support for one or more structures. Such structures may include any of: a building, accommodation, a landing area for an aircraft such as a plane or helicopter; a source of electricity such as a wind turbine, part of a tidal turbine, or any other suitable structure.

The elongate support element 158 and/or the platform element 160, preferably both, may comprise metal, plastics, wood, waste material similarly to the buoyant support element 14 of the first embodiment. Furthermore the elongate support element 158 and/or the platform element 160 may be at least partly hollow and/or may optionally comprise compartments, more preferably hexagonal compartments, similarly to the first embodiment. Detailed description of the common features is omitted for brevity. More preferably the elongate support element 158 and/or the platform element 160 comprise recycled or recyclable plastic waste. This provides a second use for the waste, which is environmentally friendly. Furthermore, plastics may be lighter than metal. The lower density of plastics, together with the elongate support element 158 and/or the platform element 160 being at least partly hollow may result in the storage system 110 being generally bottom heavy, which may further increase stability. Any of the: buoyant support element 114, the elongate element 158, the platform element 160, and the mass element 120 may provide a substrate or habitat for fauna and/or flora, thereby increasing biodiversity.

The winch mechanism 118 of the second embodiment is preferably supported or supportable by the platform element 160 and/or the elongate support element 158, rather than by the buoyant support element 114, although this alternative may be envisioned.

The winch mechanism 118 may have one or more flexible elongate elements 144, as shown. The or each flexible elongate element 144 preferably extends at least partly through the elongate support element 158 and/or the platform element 160. Furthermore, the flexible elongate element 144 extends through the buoyant support element 114 in the second embodiment, similarly to the first embodiment. The flexible elongate and the mass element 120 together form a stabilisation element, assembly, mechanism, or system, a keel element, or ballast weight. The stabilisation element in-use stabilises the aquatic energy storage system 110 in a predetermined orientation. Additionally, the stabilisation element for biasing the aquatic energy storage system 110 towards the predetermined orientation when the aquatic energy storage system 110 is displaced therefrom.

Similarly to the first embodiment, the electricity generation means 122 of the second embodiment preferably comprises at least one rotatable shaft. Detailed description of the common features of the electricity generation means 122 is omitted for brevity.

Similarly to the first embodiment, the winch mechanism 118 comprises at least one, and preferably two drums or spools 148. The or a said flexible elongate element 144 is at least partly spoolable around each spool 148. A first end of the flexible elongate element 144 is connectable to the or a said mass element 120. Preferably a second end of the flexible elongate element 144 is connectable or connected to the spool 148. The spool 148 has an axis of rotation. The axis of rotation is preferably coaxial or substantially coaxial with the rotatable shaft. This is arrangement is shown in Figure 3 and Figure 4a.

In a modified embodiment of the winch mechanism 118’ shown in Figure 4b, the winch mechanism 118’ may comprise an electricity generation means 122’, a motor 124’, at least one, and as shown, preferably five spools 148’. It is appreciated that the number of spools may be varied, as required, according to any of: the geography, topography, currents, availability, or any other suitable factor. The axis of rotation of any number of spools 148’ may be coaxial or substantially coaxial with the rotatable shaft. Additionally or alternatively, the axis of rotation of any number of spools 148’ may be non-coaxial. Furthermore, the axis of rotation of any number of spools 148’ may be non-parallel or substantially non-parallel to the rotatable shaft, but parallel or substantially parallel may be an option. More preferably, the axis of rotation of any number of spools 148’ may be perpendicular or substantially perpendicular with the rotatable shaft. In the illustrated embodiment, one spool 148’ has a coaxial axis of rotation, and four spools 148’ have an axis of rotation which is non-coaxial with the rotatable shaft. More preferably, the axis of rotation of the four spools 148’ is non-parallel. Preferably, at least one and here, all four spools 148’ have an axis of rotation which is perpendicular or substantially perpendicular to the rotatable shaft. Preferably, the winch mechanism 118’ also has at least one gear mechanism 162’. The or each gear mechanism 162’ which connects the or each, preferably perpendicular, spool 148’ and the rotatable shaft, such that rotation of the rotatable shaft rotates the or each spool 148’. There may be a plurality of through-bores 130 to accommodate one or more flexible elongate elements or flexible connectors 144’.

The aquatic energy storage system 110 also has at least one, and as shown, a plurality of mass elements 120. Preferably, each mass element 120 is connectable or connected to one flexible elongate element 144, as shown. However, it may easily be envisioned that one or more of the mass elements 120 may be connectable to at least two flexible elongate elements 144 each.

The aquatic energy storage system 110 of the second embodiment further includes a protector element or protector 164, a spacer element or spacer 166, a depth-adjustment means or mechanism 168 and a depth-measuring element or mechanism 170 but any of these features may be omitted.

The protector element 164 in-use provides protection and/or acts as a buffer between the or a flexible elongate element 144 and at least one of: the platform element 160, the elongate support element 158, and the buoyant support element 114. The protector element 164 may alternatively be referred to as a buffer element. The protector element 164 prevents or inhibits abrasion damage to the flexible elongate element 144 and/or any of: the platform element 160, the elongate support element 158, and the buoyant support element 114. In the shown embodiment, the protector element 164 is positionable in, at or adjacent to the, each or at least one recess or through-bore 130 of the buoyant support element 114.

In the simplest embodiment of the protector element 164, the protector element 164 may have a curved surface on or around which the flexible elongate element 144 may be receivable. A curved surface may have no sharp edge which could weaken, cut into or saw against the flexible elongate element 144 and/or impede spooling and/or unspooling thereof.

In a modification of the above, the protector element 164 may have a rotatable portion. The rotatable portion preferably rotates together with the flexible elongate element 144 and/or when the in-use flexible elongate element 144 is spooled or unspooled. The rotatable portion may comprise any of: one or more wheels, one or more spheres, one or more cylinders, one or more bearings, one or more beads, any other suitable rotatable portion, and any combination thereof. The or each wheel may be toothed or non-toothed. If the flexible elongate element 144 includes a chain having links, the teeth of the toothed wheel may engage with and/or be receivable within the links. The bearings may include roller or ball bearings. The bearings may optionally be at least partly embedded in the wall of the through-bore 130. The beads may include parrel beads.

The spacer element 166 in use spaces apart, maintains or substantially maintains a distance between at least two of the plurality of flexible elongate elements 144 or part thereof. In turn, this spaces apart mass elements 120 connected to the flexible elongate elements 144 such that the two or more spaced-apart mass elements 120 do not or not substantially contact and/or abut against each other. Each spaced-apart mass element 120 is therefore raisable or lowerable without interfering or inhibiting the lowering or raising of another spaced-apart mass element 120. The spacer element 166 is suspendable from at least one of: the buoyant support element 114, the elongate support element 158, and the platform element 160, preferably the buoyant support element 114 as shown. The spacer element 166 comprises a spacer-platform in the preferred element. The spacer-platform may be referred to as a spacer spider. The spacer-platform has a circular shape in plan view and a rectangular shape in side view, but any non-circular plan shape and/or any non-rectangular shape in side view may be envisioned. In other words, the spacer- platform is preferably a disc or cylinder. The spacer-platform has at least one and preferably, a plurality of spaced-apart bores and/or recesses for receiving a flexible elongate element 144 therein or therethrough. The spaced-apart bores and/or recesses may be equi-angularly disposed around the spacer-platform, but non-equi-angularly disposed may be an option.

The depth-adjustment means 168 enables adjustment of the depth of the buoyant support element 114 relative to the surface of the body of water 12 and/or relative to the platform element 160. Preferably, the depth-adjustment means 168 is dynamic so that the adjustment is dynamic. In other words, the depth-adjustment means 168 may adjust the depth of the buoyant support element 114 automatically and/or in response an input.

The input may be any of: a manual input, a predetermined input, and a measurable or measured input. A manual input may comprise a command from a user. A predetermined input may include a pre-programmed input or pre-programmed schedule of inputs. By way of example only, if the storage system 110 is positioned in a body of tidal water, the depth-adjustment means 168 may be pre-programmed to alter the depth of the buoyant support element 114 in response to the tide. A measured input may include a wave height and/or current strength. Thus, the depth-adjustment means 168 may adjust the depth of the buoyant support element 114 to compensate for waves and/or strong currents.

The adjustment may be achieved by altering the buoyancy of the buoyant support element 114. The above-described value of the ratio of the densities may thus be continuously or substantially continuously varying or variable within the defined range, rather than a set value. The depth- adjustment means 168 may therefore comprise a buoyancy-altering element, portion, mechanism or buoyancy engine. Preferably, the buoyancy-altering element may comprise a bladder or bladder element. The bladder element may be inflatable or debatable with a fluid, which may be a liquid or a gas. The gas may be air. Alternatively, the fluid may comprise a hydraulic fluid, although any suitable fluid may be envisioned.

The depth-measuring element 170 measures or estimates the depth of the, each or at least one of the mass elements 120 relative to the floor of the body of water 12 and/or to the surface. The depth-measuring element 170 may also be referred to as a depth-sounding element, sounding element or sounding mechanism. The depth-measuring element 170 may therefore comprise a range finder element to measure the distance to the floor of the body of water 12 from the surface and/or from or at least one mass element 120. Alternatively, if the total depth is known, the depth measuring element 170 may instead measure or estimate the distance the or a said mass element 120 has been lowered. The range finder element may be used to measure or estimate the depth of the mass element 120. The range finder element may comprise a sonar and/or a lidar. Calculating the difference between the total depth and the depth of the mass element 120 provides the remaining distance before the mass element 120 reaches the floor.

In-use, the aquatic energy storage system 110 of the second embodiment is provided. Assembly and functioning of the aquatic energy storage system 110 of the second embodiment is similar to the first embodiment. Detailed description of the common steps is therefore omitted, yet again, for brevity.

The motor 124, winch mechanism 118 and/or electricity generation means 122 are connected to the platform element 160 and/or the elongate support element 158, preferably the former. The, each or at least one flexible elongate is preferably made to extend through at least the buoyant support element 114, and optionally through the platform and/or the elongate support element 158.

If using a spacer element 166, the or at least one flexible elongate element 144 is made to extend through a recess or through-bore of the spacer-element to space apart a plurality of flexible elongate elements 144. The or each mass element 120 is connected to at least one flexible elongate element 144.

Once in an assembled condition, the aquatic energy storage system 110 has a predetermined orientation, equilibrium or resting position in situ. The mass element 120 and the flexible elongate element 144 together form a stabilisation element which stabilises the storage system 110. The mass element 120, which is preferably suspended at all times, may lower the centre of gravity of the storage system 110. This may result in the storage system 110 having a greater resistance to be displaced from the predetermined orientation. Furthermore, the or each unspooled portion of a flexible elongate element 144 is taut and/or under tension. Preferably the unspooled portion of the or each flexible elongate extends linearly along one direction when the storage system 110 is in the predetermined orientation. This advantageously reduces or prevents any friction and/or pressure or force being applied to the buoyant support element 114 by the flexible elongate element 144.

When the aquatic energy storage system 110 is displaced from the predetermined orientation, the stabilisation element biases the aquatic energy storage system 110 back towards the predetermined orientation. Due to the flexible elongate element 144 or elements going through the buoyant support element 114 when the storage system 110 is tilted or displaced away from the predetermined orientation, the or at least one flexible elongate element 144 may become at least partly curved and/or bent. In other words, the or at least one flexible elongate element 144 may extend along more than one direction. The or each curved and/or bent flexible elongate element 144 may apply a restoring force to the storage system 110 and/or a pushing force against the buoyant support element 114.

However, it could easily be envisioned that the unspooled portion of a said flexible elongate element 144 may not extend linearly along one direction when the storage system 110 is in the predetermined position. In this alternative, displacement from the predetermined position may increase the bending and/or curvature of the flexible elongate element 144 further. This in turn may apply the restoring force.

If provided with a protector element 164, the protector element 164 acts as a buffer and/or protects the buoyant support element 114 and the or each flexible elongate element 144 by reducing or preventing abrasion damage.

If a depth-measuring element 170 is provided, the relative depth of the mass element 120 is monitored. As it is preferable that the or each mass element 120 never reaches the floor of the body of water 12, the depth-measuring element 170 may provide an indication and/or trigger an alert when a said mass element 120 is approaching the floor.

If a depth-adjustment means 168 is provided, the absolute vertical position of the platform may be maintained or substantially maintained by the depth-adjustment means 168 adjusting the buoyancy of the buoyant support element 114, such as in response to a user input, wave height and/tides. This may reduce seasickness and/or enable aircraft to land or land more safely if the support system further comprises a landing area. In turn this may facilitate servicing of offshore structures which may otherwise be difficult to access. An offshore structure may include any energy-generating structure, such as an offshore wind turbine or a tidal turbine; or an oil rig.

The energy-generating structure may be associated with or supported by the storage system 110. If the energy-generating structure is not associated with or supported by the storage system 110, a marine vessel such as a ship or boat may be associated, connected to, or provided with the aquatic energy storage system 110. When an adjacent energy-generating structure requires servicing, an engineer or other user may be flown out to the aquatic energy storage system 110 equipped with a landing area. The engineer may then access the marine vessel and travel via the marine vessel to the energy-generating requiring maintenance. Following maintenance, the engineer may return to the aquatic energy storage system 110 via the marine vessel, then back to land via the aircraft. Referring now to Figures 5 and 6, there is shown a third embodiment of an aquatic energy storage system 210 for selectably storing and releasing energy.

Features of the third embodiment which are similar to the first embodiment or the second embodiment have similar reference numerals with the prefix “2” added or replacing the previous prefix.

The third embodiment of the aquatic energy storage system 210 is similar to the second embodiment, having at least one buoyant support element or buoyant support 214; geostationary location means or assembly; at least one winch mechanism 218 having at least one flexible elongate element or flexible connector 244, at least one mass element or mass 220 connectable to the flexible elongate element 244; an electricity generation means or mechanism 222, at least one elongate support element or elongate support 258; and at least one platform element or platform 260. The aquatic energy storage system 210 of the third embodiment further includes a protector element or protector, a depth-adjustment means or mechanism, and a depth-measuring element or mechanism, not shown, but any of these features may be omitted. Detailed description of the common features is omitted for brevity.

As shown, the third embodiment has three buoyant support elements 214. Preferably at least two, and more preferably all three buoyant support elements 214 are connected or connectable together via a connection means, mechanism or connector 272, as best shown in Figure 6, although the buoyant support elements may be non-connected to each other. This may form a tri float system, which may provide additional stability. The connection means 272 preferably includes at least one and here, a plurality of beams or framework, although any alternative connection means may be envisioned, such as a chain, a rope, or any other suitable connector.

Furthermore, the third embodiment has one elongate support element 258 per buoyant support element 214, such that three elongate support elements 258 are provided.

The or each platform element 260 is at least partly curved in plan view. Preferably, the or each platform element 260 is non-circular in the third embodiment. More preferably, the or each platform element 260 may comprise at least one extension. In other words, each platform element 260 may be considered to be lobed and/or lachrymiform. Preferably, the extensions may extend towards another platform element 260 or an extension thereof, associated with another elongate support element 258 and/or buoyant support element 214. Two or more extensions may optionally meet, join or connect, as shown. Thus, at least two, and here, three platform elements 260 are connectable, connected or integrally formed with each other. At least two connected or integrally formed platform elements 260 may together form a super platform. The super platform is preferably associated with at least two, and more preferably all three buoyant support elements 214. In other words, the super platform is preferably therefore shared between or common to a plurality of buoyant support elements 214. The super platform is here trilobed, but any number of lobes may be envisioned.

Similarly to the second embodiment, at least one of: the super platform, a said platform element 260, a said elongate support element 258, and a said buoyant support element 214 may provide a support for one or more structures which may include any of: a building, accommodation, a landing area for an aircraft such as a plane or helicopter; a source of electricity such as a wind turbine, a tidal turbine, or any other suitable structure. If a landing area, the landing area is preferably positioned at or adjacent where the platform extensions meet, but this feature may be omitted.

Preferably, each buoyant support element 214 only supports one mass element 220 as shown but a plurality of mass elements may be envisioned. Each mass element 220 is only supported by one flexible elongate element 244 but, once again, a plurality of flexible elongate elements may support a mass element. Furthermore, no spacer element or spacer is provided in the third embodiment, but this may easily be an option.

In-use, the assembly and use of the third embodiment are similar to the second embodiment. Detailed description of the common features is omitted for brevity.

Preferably in the first, and second embodiments, there is one buoyant support element, one support body and one channel per support element, one geostationary location means, one winch mechanism, one mass element, one electricity generation means, one generator, one winch, one shaft, one motor, one locking means, one net portion, one anchor and one tether per anchoring element, one flexible elongate element, one drum-rotation means, one drum-engagement means, and one cable. Furthermore, the first embodiment has three anchoring elements whilst the second and third embodiments have at least one but preferably fewer than three anchoring elements. The third embodiment has three buoyant support elements, one support body and one channel per support element, one geostationary location means, three winch mechanisms, three mass elements, three electricity generation means, three generators, three winches, three shafts, three motors, three locking means, three net portions, one anchor and one tether per anchoring element, three flexible elongate elements, three drum-rotation means or mechanism, and three drum-engagement means. However, there may be any number of any of the above features, including none, one, two, or more. A plurality of elongate elements may optionally be spoolable around a common drum-engagement means. In any of the above embodiments, although the energy storage system, and more specifically the winch mechanism thereof comprises a motor to wind or spool the flexible elongate element, in addition to or instead of the motor, it may be envisioned that manual rotation means or mechanism, such as a handle, may be provided for enabling the elongate element to be wound or spooled manually. This may provide a back-up mechanism and/or enable the mass element to be raised for maintenance or servicing purposes.

Whilst a uniform or substantially uniform mass distribution of the support body is preferable, a non-uniform mass distribution may be an option. In this alternative, the first centre of gravity may be offset or laterally displaced from a central position or location of the support body.

In any of the above embodiments, the geostationary means comprises at least one anchoring element, each anchoring element having an anchor. However, an alternative anchoring element may be envisioned. For instance, the or each anchoring element may comprise an existing structure, in addition to or instead of the anchor and/or tether. As such, the predetermined position of the support element may be geostationarily or substantially geostationarily maintained by engaging, connecting, or tethering the support element to an existing structure.

Although the support element here comprises a floating support body, any alternative may be envisioned. For instance, the support element may comprise an existing structure, in addition to or instead of the floating support body.

It may even be considered that both the floating support body and at least part of the geostationary means may be replaced by an existing structure which may fulfil both supporting and positioning functions simultaneously. In this alternative, the mass element may be connected or connectable directly to the existing structure. The mass element may be retrofittable.

In any of the above cases, an existing structure may include an offshore wind turbine or at least the support tower thereof, a mooring pole, a telecommunications mast, an offshore oil platform or rig or at least a leg or support thereof, or any other suitable existing structure, any combination thereof and/or a plurality of any of the above.

In a further alternative embodiment, the aquatic energy storage system may comprise at least two support elements. At least one support element may be tethered, connected or connectable to at least one further support element and/or to at least one existing structure as described above. A plurality of support elements may extend in or form a row. The row may extend between and/or be connected to a plurality of existing structures. Preferably, one or both ends of the row may be connected or connectable to at least one existing structure. Both ends may even be connectable to the same existing structure or structures. A common geostationary means may be provided for a plurality of support elements. Optionally, the geostationary means of connected support elements may comprise the existing structure or structures instead of or in addition to an anchor and/or tether. Furthermore, a common winch mechanism or part thereof, such as the drum-engagement means, may be provided for at least two said support elements. More preferably, the common drum-engagement means may comprise a shaft. The shaft may extend along, between, across and/or through at least two support elements. The shaft may be rotationally stiff or rigid. The, each, or at least one elongate element of each support element may be spoolable around the common drum-engagement means. Advantageously, the shaft may be simultaneously at least partly flexible, laterally and/or along the longitudinal extent thereof. In other words, the shaft may be bendable, deformable, or pliable whilst being able to convey, apply or impart rotational torque. This flexibility may beneficially prevent or reduce the risk of the drum- engagement means breaking or sustaining damage, if two support elements connected by the common shaft are displaced vertically and/or horizontally relative to each other. This may occur, for example, due to waves. Optionally, the shaft may be the only means of connecting support elements to each other. Furthermore, a common electricity generation means or part thereof, such as the at least one generator, may optionally be provided for at least two said support elements.

In the any of the above embodiments, the support element is a coaxial annulus in plan view and/or lateral cross-section. However, 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.

Although the channel and the mass element are or are substantially circular in plan view and/or in cross-section, the channel and/or the mass element may be non-circular. The buoyant support element has a circular perimeter and the channel such that it is an annulus in cross-section, but a non-annulus may be envisioned. Any of the channel, the support element, the mass element, or any further above-mentioned feature in any embodiment 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, slit-shaped, slot-shaped, 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 respective shapes in lateral and/or longitudinal cross- section of the channel and the support element may differ from each other. The cross-section of any of the channel, the mass element, and the support element may optionally change along the longitudinal and/or latitudinal extent of the channel, mass element, and/or the support element.

The channel, although preferably closed in any of the above embodiments, may be open along at least part of the longitudinal extent. In other words, the support element may not fully surround or enclose the channel and/or elongate element in-use received therein. This may be easier for installation and maintenance purposes. For example, it may be easier to install and/or replace the mass element. In this alternative embodiment, the channel may be considered to be a recess, a slit, a slot, a groove, an opening, a conduit, a concave portion, or a section of a pipe. The open channel may be positioned at, in or on the or a perimeter wall and may optionally extend at least partly inwards, from the or a perimeter wall. There may be a plurality of channels. Optionally, for stability, a first of the plurality of channels may be spaced-apart from a second said channel. If two open channels are provided, they may be opposite each other. If the support body has a circular perimeter, the channels may be diametrically opposed. If three or more open channels are provided, the channels may optionally be equidistant around the support element. Each channel may receive an elongate element. Each elongate element may be connected to the same or to a different mass element, and/or to the same or a different winch. There may even be at least one open channel and/or at least one closed channel.

Beneficially, at least two buoyant support elements may each support one or more independent mass elements. This may enable fine-tuning of the energy storage and supply capacity. It may be envisioned however that at least two said support elements may support at least one common mass element.

The buoyant support element and/or the elongate support element is preferably integrally formed. However, either or both may be assembled from sub-units or modules. In other words, the buoyant support element and/or the elongate support element may be modular.

Although preferably in the second and third embodiments, the or each flexible elongate element extends through all three of the platform element, the elongate support element, and the buoyant support element, in a further modification, the, each or at least one flexible elongate element may extend through only the buoyant support element, or only the buoyant support element and one of: the platform element and the elongate support element. In other words, the, each or at least one flexible elongate element may extend at least partly outside of the elongate support element and/or of the platform element. For example, the or at least one flexible elongate element may extend from and/or along a side surface or edge of a said platform element. A plurality of elongate support elements may extend from one or more buoyant support elements. Optionally, a said flexible elongate element may extend between them from a said platform element to a said buoyant element.

In an alternative embodiment, one or more of the flexible elongate elements may split or diverge into at least two flexible elongate sub-elements along at least part of the longitudinal extent of the flexible elongate element. Although the buoyancy-altering element preferably comprises a bladder, the bladder may easily be omitted. For instance, a plunger system may be provided instead to alter the buoyancy of the buoyant support element and/or elongate support element. Furthermore, the depth-adjustment means may not comprise a buoyancy-altering element. Instead of or in addition to altering the buoyancy of the buoyant support element, the distance between the platform element and the buoyant support element may be altered. This may be achieved by having a spacing-altering element. The spacing-altering element may comprise a connecting mechanism connecting the platform element and the or the plurality of elongate support elements. The connecting mechanism may enable the platform element to move and/or translate axially along the longitudinal extent of the or each elongate support element, or part thereof. Alternatively, the or the plurality of elongate support elements may be at least partly telescopic.

Instead or in addition to a range finder element or range finder, the depth-measuring element may have a length-estimator element associated with the electricity generation means and/or winch mechanism. The length-estimator element may estimate the unspooled or spooled length of the flexible elongate element. In other words, the length-estimator element can estimate how much a flexible elongate element has been unspooled or spooled. This can be done by counting the number of rotations of the generator and/or the winch mechanism.

Although the second end of the flexible elongate element is connectable or connected to the spool in all the above embodiments, it could easily be envisioned that the second end may be non- connectable or non-connected to the spool. In this alternative embodiment, the flexible elongate element may be preferably wrapped around the spool at least once, and more preferably a plurality of turns. This may be necessarily to provide sufficient friction between the spool and the flexible elongate element to avoid or minimise the risk of the flexible elongate element becoming unwrapped. The second end may be a free end and/or or connectable to another element of the storage system or be. Alternatively, the aquatic energy storage system may further comprise a weight to which the second end is connectable. The weight may even be a further mass element.

Although a spacer-platform which pushes the flexible elongate elements apart is the preferred embodiment, any suitable alternative which pushes the flexible elongate elements apart may be envisioned. For instance, a beam, bar, pole, rod or framework may be equally suitable. Furthermore, the spacer element acts by pushing the flexible elongate elements apart, however it could easily be envisioned that the spacer element may instead pull the flexible elongate elements apart.

In the second and/or third embodiments, the platform element provides a support for one or more structures which may include any of: a building, accommodation, a landing area for an aircraft such as a plane or helicopter; a source of electricity such as a wind turbine, a tidal turbine, or any other suitable structure. However, alternatively or additionally, it may easily be envisioned that the elongate support structure and/or the buoyant support element may support one or more said structures.

Although in all the embodiments, the or each flexible elongate element extends from, and more preferably, through the buoyant support element, it could easily be envisioned that the, each or at least one flexible elongate element may not extend through the buoyant support element. For instance, the or a said flexible elongate element may abut against or extend along a side surface of the buoyant support element. The or a said flexible elongate element may even be spaced- apart from the buoyant support element.

The rotatable shaft preferably extends horizontally or substantially horizontally in use. It may, however, be envisioned that the rotatable shaft may instead be at least partly vertically or substantially vertically orientated. Any spool thereupon may therefore also be at least partly vertical or substantially vertical. A guide element or guide may need to be provided to enable a flexible elongate element, which extends vertically or substantially vertically in use, to be wrappable around an at least partly vertical spool. Such a guide element may include a pulley and/or a curved surface by way of example only.

It is therefore possible to provide an aquatic storage system for storing energy when the electricity grid has a surplus and converting stored energy into electricity when the electricity grid has a deficit. Converting excess electricity into potential energy is a quiet, simple, and reproducible means of storing energy. Conversion back into electricity is rapid. As out at sea, the aquatic storage system is out of sight. The risk of fire is reduced. The aquatic storage system is environmentally friendly as non-toxic, requiring no components obtaining through mining, the system repurposes waste and may even provide a habitat for aquatic life. The shape of the mass element may reduce the drag forces, thereby increasing the efficiency of the energy storage system further. Storage capacity reduces very little over time and usage. It is therefore also possible to provide an aquatic energy storage system having a greater stability by virtue of having a stabilisation element. Furthermore, by having a submersible buoyant support element, and a platform element supported by and spaced-apart therefrom by a thin, elongate support element, the effect of waves and/or currents is mitigated. It is also possible to provide a method of stabilising an aquatic energy storage system.

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 other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined herein.