GB2596284A

GB2596284A - Aquatic energy storage system and method of use thereof

Info

Publication number: GB2596284A
Application number: GB2009245.8A
Authority: GB
Inventors: Knight Jeremy
Original assignee: Energy Storage Ltd
Current assignee: Energy Storage Ltd
Priority date: 2020-06-17
Filing date: 2020-06-17
Publication date: 2021-12-29
Also published as: GB2596377B; GB2596368A; WO2021255417A1; GB202017453D0; GB2596377A; GB202101556D0; GB202009245D0

Abstract

An aquatic energy storage system 10 is able to store and release energy by raising and lowering a weight 20 in a body of water. A buoyant support element 14, which preferably has a plurality of internal compartments 38, supports a winch mechanism 18, which holds a mass element 20. The energy storage system 10 is maintained in position by a geostationary location means 16 such as a mooring system 40, 42. The energy storage system 10 stores energy as potential energy and generates electricity from substantially vertical translation of the mass element 20 under gravity into the deep body of water 12 when the winch mechanism 18 unspools the flexible elongate element 44. The support element may comprise or contain waste recyclable or non-recyclable material, possibly forming a wall of an internal compartment.

Description

Aquatic Energy Storage System and Method of Use Thereof The present invention relates to an energy storage system for storing 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 there when they need it. Whilst often taken for granted, this requires a reliable electricity grid to which electricity is supplied and from which electricity is drawn.

The electricity grid has a frequency which must be kept 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, the frequency changes. Damage to devices or even blackouts may ensue. In the absence of any frequency-stabilising mechanism, the supply of electricity does not match the demand at any one time.

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 present 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 deep 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 deep body of water when the winch mechanism unspools the flexible elongate element.

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.

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.

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 5 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 10 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.

The invention will now be more particularly described, by way of example only, with 15 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 20 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.

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 30 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 5 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 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. 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. 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 comprises at least one and preferably three, anchoring elements 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 30 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 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 5 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 10 end, the elongate element 44 further comprises an engagement means, not shown for engaging with the mass element 20.

The engagement means 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 15 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 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 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 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 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 manmade 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 5 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-30 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 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 5 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 25 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 geostafionary location means 16 is made to 5 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 10 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, 20 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 15 selectably storing excess energy as potential energy in an aquatic environment and generating electricity from the said stored potential energy is provided.

Although in the present embodiment, there is one 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, three anchoring elements, one anchor and one tether per anchoring element, one elongate element, one drum-rotation means, one drum-engagement means, one cable, 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.

Although the energy storage system, and more specifically the winch mechanism thereof comprises a motor to wind or spool the elongate element, in addition to or instead of the motor, it may be envisioned that manual rotation means, 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 the present embodiment, 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 geostafionarily 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 preferred embodiment, the support element has a coaxial annulus in plan view. However, a non-coaxial annulus may be envisioned instead. In this case, the respective 20 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 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 support elements may each support one or more independent 20 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 support element is preferably integrally formed. However, the support element may be assembled from sub-units or modules. In other words, the support element may be 25 modular.

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.

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 5 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.

Claims

Claims 1. 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.
2. An aquatic energy storage system as claimed claim 1, wherein at least one said internal compartment is sealed.
3. An aquatic energy storage system as claimed in claim 1 or claim 2, wherein at least one said internal compartment has a hexagonal cross-section.
4. An aquatic energy storage system as claimed in claim 3, wherein a plurality of said internal compartments form a hexagonal lattice structure.
5. An aquatic energy storage system as claimed in any one of the preceding claims, wherein at least one said internal compartment contains a buoyancy-providing element.
6. An aquatic energy storage system as claimed in any one of the preceding claims, wherein the buoyant support element comprises recyclable waste.
7. An aquatic energy storage system as claimed in any one of the preceding claims, wherein the buoyant support element comprises unrecyclable waste.
8. An aquatic energy storage system as claimed in claim 6 or claim 7, wherein the waste comprises plastics.
9. An aquatic energy storage system as claimed in any one of claims 6 to 8, wherein the waste is contained within at least one said internal compartment.
An aquatic energy storage system as claimed in any one of claims 6 to 9, wherein at least one said internal compartment has a wall comprising said waste.
11. An aquatic energy storage system as claimed in any one of the preceding claims, wherein the buoyant support element comprises a major upper surface, a major lower surface, and a channel extending therebetween.
12. An aquatic energy storage system as claimed in claim 11, wherein the channel is centrally positioned relative to the buoyant support element.
13. An aquatic energy storage system as claimed in claim 12, wherein the buoyant support element has a toroidal body.
14. An aquatic energy storage system as claimed in claim 13, wherein the buoyant support element has a square toroidal body or a rectangular toroidal body.
15. An aquatic energy storage system as claimed in any one of the preceding claims, wherein the mass element has 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.
16 An aquatic energy storage system as claimed in any one of the preceding claims, wherein the mass element comprises at least one rock.
17. An aquatic energy storage system as claimed in any one of the preceding claims, wherein the mass element comprises waste.
18 An aquatic energy storage system as claimed in claim 16 or claim 17, wherein the mass element further comprises a net portion for receiving the at least one rock and/or the waste.
19 An aquatic energy storage system as claimed in any one of claims 16 to 18, wherein the mass element further comprises 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.
An aquatic energy storage system as claimed in any one of the preceding claims, wherein the geostationary location means comprises an anchor.
21. An aquatic energy storage system as claimed in any one of the preceding claims, further comprising a motor associated with the winch mechanism for raising the mass element by spooling the flexible elongate element.
22 An aquatic energy storage system as claimed in claim 21, wherein the winch mechanism comprises a shaft which is rotatable by the motor for spooling the flexible elongate element.
23. An aquatic energy storage system as claimed in any one of the preceding claims, further comprising an electric cable connectable to the electric generator and to an onshore energy grid.
24. 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; 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.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 as claimed in any one of claims 1 to 24; 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.