WO2022038503A1

WO2022038503A1 - Hybrid electricity producing arrangement

Info

Publication number: WO2022038503A1
Application number: PCT/IB2021/057549
Authority: WO
Inventors: Thomas Robbert Paul LEUNISSEN
Original assignee: Aquamarine Foundation; PIENAAR, Danie
Priority date: 2020-08-17
Filing date: 2021-08-17
Publication date: 2022-02-24
Also published as: NL2026280B1; EP4196677A1

Abstract

A hybrid electricity producing arrangement or generating system (10), producing electricity from various renewable sources. The system (10) or arrangement comprises an elongate structure (18) extending above a water surface (20) of a body of water (22), and a float (42) defining an inner cavity (44) through which the elongate structure (18) extends in use. The arrangement is such that the float extends at least 50% around a periphery of the elongate structure. A fixing arrangement (46) is provided for displaceably fixing the float (42) relative to the elongate structure. The fixing arrangement (46) facilitates displacement of the float (42) relative to the elongate structure (18), in at least a first and second degree of freedom. At least a first energy transfer device (76) extends between the float (42) and the elongate structure (18), and is actuated by displacement of the float (42) relative to the elongate structure (18).

Description

HYBRID ELECTRICITY PRODUCING ARRANGEMENT

BACKGROUND TO THE INVENTION

This invention relates to a hybrid electricity producing arrangement. More particularly, the present invention relates to a hybrid electricity producing or generating system, producing electricity from various renewable sources, in one structure. Furthermore, the invention extends to the production of auxiliary power for such a hybrid electricity producing or generating system.

Dwindling fossil fuel resources, increased focus on the lowering of carbon emissions and the prevention of pollution have seen an increase in the demand for generating electricity from renewable and clean resources, in recent times.

“Renewable electricity” refers to electricity generated or obtained from natural resources, which resources are replenished constantly, or cannot be depleted. Solar energy, wind energy, hydroelectric energy, biomass energy, geothermal energy, tidal energy, and wave energy are all known renewable sources, utilised for the generation of electricity, today.

According to some studies, in 2018, less than 30% of electricity generated globally, was generated from renewable resources. Estimates predict that by 2040, up to 45% of the global electricity demand will be supplied from natural resources.

However, at present, the use of renewable resources is not always viable enough to support large-scale implementation of such resources in the generation of electricity. Two main contributing factors to this, are the energy density or power density of renewable sources, and the efficiency of generating distributable electricity from such sources.

Energy density refers to the amount of energy stored, contained, or generated in a system, per unit area or volume. For example, globally on average, the power density of solar radiation (and therefore the available power for conversion to electricity) is between 170 W/m² and 200 W/m². That said, current photovoltaic cells and solar generating systems typically have efficiencies below 20%.

Conventional fossil fuel power plants, in contrast, have energy densities orders of magnitude greater than that of renewable energy generating systems. Furthermore, the capital and maintenance cost of some renewable systems as a function of its energy generating potential are relatively high, compared to that of fossil fuel or other non-renewable generating systems. For example, the construction costs of offshore wind turbines, including a tower, piling same into the seabed, the cost of underwater power cables and the like, are very high. Therefore, it would be advantageous if the total energy generated by the equipment could be increased, in order to drive the unit-cost of the generating electricity asset down. Conventionally, increasing the energy density of a wind turbine involves providing larger, taller, and heavier towers with larger turbine blades. This is very costly, while the electricity generating potential of the installation is still fully dependent on a single source of renewable energy, namely wind.

In addition, (except for a few) many renewable energy resources are not as stable or reliable as fossil fuel alternatives. For example, energy generation from solar radiation is, obviously, only possible during the day, and becomes less efficient during times of cloudy or overcast weather. Similarly, energy generation utilising wind turbines is a function of the wind speed, while energy generation from waves or underwater currents are a function of the size of the waves or currents.

A need therefore exists for improved energy generating systems, which could potentially improve the efficiency or the economic viability of generating energy from renewable or clean resources.

One way of improving the efficiency, economic viability and energy density associated with the generation of renewable energy, is by providing hybrid electricity producing arrangements. “Hybrid”, in this sense refers to a single arrangement producing electricity from more than one source of renewable energy. By providing a hybrid electricity producing arrangement, the unit asset cost of electricity production per Megawatt can be reduced, while the amount of electricity, and therefore the energy density of the arrangement can be increased.

Implementation of offshore generation of electricity using hybrid electricity producing arrangements have to date been slow, due to practical constraints. Generally, when it comes the generation of electricity from wave energy, the following constraints need to be considered:

1 ) The size of the float (displaced or floating volume of the float is linked to the amount of energy that can be generated). Consequently, the size of the float needs to be optimized for maximum electricity production.

2) The size or weight of the supporting structure relative to which the float is fixed. Upward forces transmitted from the float to the supporting structure need to be resisted. In some cases, such as when the float is fixed relative to the mast of a wind tower, the size or weight of the wind tower would limit the permissible size and upward forces of the float.

3) Stresses associated with fixing the float relative to the supporting structure. In most cases where floats are fixed to the mast by way of articulating arms, large bending stresses are transmitted to the mast, caused by moments about vertical axes through the connecting points between the supporting structure and the articulating arms. Reference is made to figure 32 which indicates a known float system with floats connected to a mast by way of articulating arms. Also, lateral wave load forces exerted on the float and mast by currents need to be resisted by the mast. It will be appreciated that longer articulating arms are associated with higher bending moments (M2) at the fixing points of the articulated arms to the mast. Due to the nett lateral or horizontal wave load (Fn (which includes F2)), the lateral or horizontal catchment area of the float needs to be minimized.

4) Complexity and number of moving parts need to be minimized, since the arrangement is necessarily installed in abrasive conditions.

DE 10 2010 054 358 A1 discloses an offshore hybrid electricity producing arrangement incorporating a wind turbine, a wave energy generating float, and underwater current energy generating turbines. Separate floats associated with articulating arms (as shown in figure 32), or a single rigid float axially displaceable relative to the mast (single degree of freedom “DOF” - as shown in figure 31 ) is provided. It is considered that both alternatives of the float result in high stresses transmitted to the mast. As mentioned, the articulating arms transmit large bending stresses to the mast, also caused by lateral forces (F2) exerted by tides on the floats. The single DOF axially translatable float also causes bending stresses. Specifically, when a wavefront (indicated by S in figure 31 ) initially contacts the float, an upward force (F1 ) is transmitted to an end of the float. Since the float cannot articulate or pivot, a large bending moment (M1 ) is transmitted to the mast. It is foreseen that this bending moment (M1 ) could cause the float easily to jam or become wedged (typically at pinch points marked P) and/or could cause large bending stresses on the mast and could, for example, cause buckling at point B. The “pinching” or bending increases friction and losses and therefore reduces efficiency of the system.

CN109185025A discloses an offshore hybrid electricity producing arrangement incorporating a wind turbine and a wave energy generating float. Again, separate floats associated with articulating arms are provided. However, the articulating arms are mounted to a sleeve which is axially displaceable relative to the mast. Similar drawbacks, such as complexity and number of moving parts, the size of the lateral or horizontal wave load caused by the lateral or horizontal catchment area of the float, and the size of the volume of the float relative to the catchment area thereof, are present. It is furthermore submitted that the location of pivots between the floats and the articulating arms, and the position of the mounting point between the float and the arms, render this arrangement inutile or at least very inefficient. DE 10 2014 004 964 A1 discloses a deep-sea floating hybrid electricity producing arrangement incorporating a wind turbine and a wave energy generating float. However, axial displacement of the mast of the wind tower relative to the float is not permitted since the float supports the weight of the wind tower. Therefore, electricity produced by the float arrangement is limited to relative articulation between the mast and the float.

CN 108 457 805 A discloses an offshore hybrid electricity producing arrangement incorporating a wind turbine and a “duck type” articulating wave energy generating float. It is considered that the potential energy generated by this duck-type system is very limited. Also, provision needs to be made for the rotation of the duck-type float relative to the mast to allow alignment thereof with the waves. This is believed to add complexity to the arrangement.

A need therefore exists for a hybrid electricity producing arrangement with which some of the drawbacks of the aforementioned arrangements can be addressed, to enable larger scale implementation of offshore generation of electricity using hybrid electricity producing arrangements. Specifically, a need exists for an arrangement in which the volume of the float can be maximised, while limiting the horizontal catchment area thereof, and while limiting or at least reducing stresses transmitted to the mast of the tower to a minimum.

As a safety precaution during heavy winds and/or storms, the nacelle hub and turbine blades are turned out of the wind, brakes are activated, and the turbine is caused to stop rotating, and therefore stops generating electricity.

However, the wind turbine requires power to operate and to resume function once weather permits same. Therefore, wind towers are provided with auxiliary power, by means of additional sub-sea power cables, on-board fossil fuel generators or battery and/or UPS systems. Sub-sea, auxiliary power supplying cables are costly to install, and fossil fuel generators are costly to refuel and maintain in an offshore location. A need therefore also exists for a system of supplying auxiliary power to the tower, which is available, even during inclimate weather.

It is accordingly an object of the invention to provide various forms of electricity generating and/or storage systems that will, at least partially, address the above disadvantages.

It is also an object of the invention to provide various forms of electricity generating and/or storage systems which will be a useful alternative to existing energy generating systems. SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided an electricity generating system comprising: an elongate structure extending above a water surface of a body of water; a float defining an inner cavity through which the elongate structure extends in use, the arrangement such that the float extends at least 50% around a periphery of the elongate structure; a fixing arrangement for displaceably fixing the float relative to the elongate structure wherein the fixing arrangement facilitates displacement of the float relative to the elongate structure, in a first and second degree of freedom; and at least a first energy transfer device extending between the float and the elongate structure, which is actuated by displacement of the float relative to the elongate structure.

Second and further energy transfer devices may extend between the float and the elongate structure, and may also be actuated by displacement of the float relative to the elongate structure.

The float may surround the elongate structure completely. The first degree of freedom may be a translational degree of freedom, such as in a z-axis of a Cartesian coordinate system. The fixing arrangement may therefore facilitate axial displacement of the float relative to the elongate structure when the float is displaced in the first degree of freedom. The second degree of freedom, on the other hand, may be a first rotational degree of freedom. The fixing arrangement may therefore facilitate rotational/pivoting displacement of the float relative to the elongate structu re. The rotational or pivoting displacement of the float in the second degree of freedom may be about a first axis, such as an x-axis of Cartesian coordinate system, which may extend substantially horizontally.

The fixing arrangement may facilitate displacement of the float relative to the structure, in a third degree of freedom, which may be a second rotational degree of freedom. The fixing arrangement may facilitate rotational/pivoting displacement of the float relative to the elongate structure and about a second axis, such as a y-axis of a Cartesian coordinate system, which may extend substantially horizontally and substantially perpendicularly relative to the first axis.

The fixing arrangement may comprise a main body, in the form of a collar which may be axially displaceable relative to the main structure. The fixing arrangement may furthermore include a first pivot for facilitating rotational/pivoting displacement of the float within the second degree of freedom. Furthermore, the fixing arrangement may include a second pivot for facilitating rotational/pivoting displacement of the float within the third degree of freedom. The first pivot may be provided between the main body of the fixing arrangement and the float. A first end of the first pivot may be fixed to the main body of the fixing arrangement.

The fixing arrangement may also comprise an intermediate body. A second end of the first pivot may be fixed to the intermediate body. A second pivot may be provided between the intermediate body and the float, such that a first end of the second pivot may be fixed to the intermediate body, while a second end of the second pivot may be fixed to the float.

The first and second pivots may be arranged substantially perpendicularly to each other about the elongate structure.

The collar may constitute a linear bearing and may include one of a plurality of rollers and slides for supporting the fixing arrangement relative to, and for running on, an outer surface of the elongate structure. In cases where rollers are provided, the rollers may be mounted to the collar by way of bearings.

The elongate structure may comprise a functional portion and a base portion. In use, the base portion may be anchored to a bed of the body of water. The functional portion of the elongate structure may extend between 2 and 10 meters below a nominal surface level of the body of water, and between 2 and 25 meters above the nominal surface level of the body of water.

Typically, the functional portion of the elongate structure may extend at least 4 meters below a nominal surface level of the body of water, and at least 8 meters above the nominal surface level of the body of water. In some examples, the functional portion of the elongate structure may extend about 4, 5, 6, 7, 8, 9 or 10 meters below the nominal surface level of the body of water, while the functional portion of the elongate structure may extend about 4, 5, 6, 7, 8, 9, 10, 11 , 12 ,13, 14, 15, 16, 17, 18, 19, 20, 21 , 22, 23 ,24 or 25 meters above the nominal surface level of the body of water.

A cross-section of the functional portion of the elongate structure may be substantially constant along a length thereof. The cross-section of the functional portion may be substantially circular or a polygon, such as a regular polygon (having sides of substantially equal lengths).

The elongate structure may comprise a tower, mast, or pile of an offshore wind turbine. In some examples, the base portion of the elongate structure may comprise a lattice structure. The float may be substantially ring-shaped in plan. Alternatively, an outer shape of the float viewed in plan may be in the form of a polygon, such as a regular polygon, which regular polygon has 3 or more sides. The polygon my typically have 3, 4, 5, 6, 7, 8, 9, 10, 11 , 1 2, 13, 14, 15, 16 or more sides. An outer bottom side portion of the float may be bevelled, rounded or convex. Top and bottom side portions of the inner cavity (i.e., inner sides or edges) of the float may be bevelled.

The float may have a volume and mass which, in use, may displace a volume of water having a mass equal to between 60% and 90% of a mass of structural parts of the system, excluding the mass of the float.

The elongate structure may be configured to be installed in the body of water, at a location where a nominal depth of the body of water is 60 meters or less.

Alternatively, the system may further comprise a support structure for supporting the elongate structure relative to a bed of the body of water. In such cases, the elongate structure may be configured to be installed in the body of water, at a location where a nominal depth of the body of water is between 30 meters and 100 meters. The support structure may typically be provided in cases where openings are formed in the elongate structure, to strengthen the elongate structure and provide additional support, in cases where the nominal depth of the body of water exceeds 60 meters, or in combinations of the aforementioned.

The support structure comprises at least a first ring member for receiving the elongate structure in use, and at least a first leg extending between the bed of the body of water and the at least first ring member. Typically, the support may comprise a second leg extending between the bed of the body of water and the at least first ring member. The first and second legs may be arranged in a push-pull configuration.

The at least first energy transfer device may comprise a first piston arrangement extending between the float and the elongate structure. Displacement of the float relative to the elongate structure may cause the piston arrangement to cause a flow of fluid in a fluid circuit.

The fluid circuit may include a fluid line, a hydraulic accumulator, and a hydraulic motor/generator unit. The hydraulic motor/generator unit may be provided in fluid flow communication with the fluid line and the hydraulic accumulator.

The system may include at least a second piston arrangement. Each of the first and second piston arrangements may be fitted between a respective first mount on the elongate structure, and a respective second mount on the float. The arrangement of the first and second piston arrangements may be one of: i) such that barrel ends of the first and second piston arrangements are fixed to the first mounts and rod ends of the first and second piston arrangements are fixed to the second mounts; and ii) such that rod ends of the first and second piston arrangements are fixed to the first mounts and barrel ends of the first and second piston arrangements are fixed to the second mounts. The system may include a third and a fourth piston arrangement. Each piston arrangement may be fitted to the first and second mounts respectively, by way of respective multi- axial pivot connection mechanisms in the form of a ball joint or universal joint.

Alternatively, the first linear energy transfer device may constitute a first primary piston arrangement. The first primary piston arrangement may be fitted between a first primary mount on the elongate structure, and a second primary mount on the main body of the fixing arrangement. The system may further include a second primary piston arrangement which may fitted between a first primary mount on the elongate structure, and a second primary mount on the main body of the fixing arrangement. Each primary piston arrangement may be a double acting piston arrangement. The system may further include a first secondary piston arrangement which may be fitted between a first secondary mount on the main body of the fixing arrangement and a second secondary mount on the float.

The system may further include a second secondary piston arrangement which may be fitted between a first secondary mount on the main body of the fixing arrangement and a second secondary mount on the float.

The float may include an internal compartment for housing the hydraulic motor/generator unit and hydraulic accumulator. Alternatively, or in addition, a compartment may be supported by the elongate structure at a location above the float, which compartment may be provided for housing the hydraulic motor/generator unit and hydraulic accumulator.

In some examples, the system may further include at least one marine turbine arrangement fixed to a bottom surface of the float.

Generally, the float may extend at least one of: 1 ) at least 50%; 2) at least 60%; 3) at least 70%; 4) at least 80%; 5) at least 90% and 6) 100%, around the periphery of the elongate structure. In some examples, therefore, the float may be substantially C-shaped when viewed in plan.

In further alternative embodiments, the energy transfer device may comprise either a rack and pinion arrangement, a linear electro-magnetic arrangement, or a piston arrangement with an integrated accumulator and/or oil tank. Combinations of these types of devices may also be provided for. In the case where the piston arrangement comprises an integrated accumulator and/or oil tank, same may further include at least one integrated valve and/or an integrated motor powering an alternator.

In accordance with a second aspect of the invention, there is provided an auxiliary power generating system for a wind-turbine located in a body of water, the wind-turbine comprising a pile having a base portion extending below a surface of the body of water, and an upper portion extending above the surface of the body of water, wherein, in use, the upper portion is filled with air, while the base portion is provided in flow communication with the body of water, such that a level of water within the pile rises and falls in sympathy with a level of the body of water, wherein the auxiliary power generating system comprises a first turbine mounted in fluid flow communication with the air within the upper portion, and, in use, driven by air displaced by the rising and falling water level within the elongate structure.

Further in accordance with the second aspect of the invention, the first turbine may be a multidirectional air turbine and wherein the system includes an opening for airflow between an outside environment and the upper portion.

In an alternative example of the second aspect of the invention, the auxiliary power generating system may furthermore comprise a second turbine. The arrangement may be such that airflow associated with a rising level of water within the pile may drive the first turbine, and such that airflow associated with a falling level of water within the pile drives the second turbine.

The first turbine may in either example of the second aspect of the invention be fixed to a base. A vertical position of the base may be displaceable in use, relative to a nominal level of the water within the pile.

In accordance with a third aspect of the invention, there is provided a current energy converter, comprising: a main structure comprising an elongate structure extending partially above a water surface of a body of water and a base structure; at least a first turbine assembly, in use, arranged within an outer periphery defined by the base structure and provided in fluid flow communication with the body of water.

The current energy converter may comprise a plurality of turbine assemblies spaced axially or vertically relative to each other within the outer periphery defined by the base structure. In cases where the base structure comprises a monopile fixed in a bed of the body of water, each turbine assembly may, in use, be aligned with a set of opposing openings through wall portions of the pile. A flow channel may be defined through each set of opposing openings. The pile may be reinforced proximate each set of opposing openings. Specifically, a reinforcing collar may be associated with each opening through the wall portion of the pile.

The pile may furthermore be reinforced by an axially extending, internal brace in the form of a tubular member, having one of a rectangular or circular cross-section.

The base structure may comprise a lattice or jacket structure defining an axially or vertically extending column within which each turbine is arranged in use.

The one or more turbines may be mounted to a mounting structure which may be axially displaceable relative to the base structure. The mounting structure may be displaceable between an operative configuration, in which each turbine is arranged in fluid flow communication with the body of water, and an inoperative configuration, in which each turbine is removed from the body of water.

The mounting structure may be located at least partially within the elongate structure when displaced into the inoperative configuration. A hoisting system may be provided for axially displacing the mounting structure.

The reinforcing collar may be formed by a respective tubular member extending between the opposed openings of each set and across the base member to define a flow channel or tunnel. Each opening may comprise a door for closing the flow channel or tunnel. Each tubular member extending between a set of openings may comprise an access hatch.

In accordance with a fourth aspect of the invention, there is provided a hybrid electricity generating system comprising: an electricity generating system according to the first aspect of the invention; and a current energy converter according to the third aspect of the invention.

The hybrid electricity generating system may furthermore include an auxiliary power generating system according to the second aspect of the invention. In accordance with a fifth aspect of the invention, there is provided a method of lifting a float of an electricity generating system according to the first aspect of the invention from a body of water, which float is displaceably fixed relative to an elongate structure, the method comprising the steps of: allowing the float to be displaced relative to the elongate structure to a first lifted position by a first wave; and retaining the float in the first lifted position after the first wave has passed.

The method may comprise the further steps of: allowing the float to be displaced relative to the elongate structure to a second lifted position by a second wave, where the second lifted position is vertically higher than the first lifted position; and retaining the float in the second lifted position after the second wave has passed.

Displacement of the float relative to the elongate structure may be associated with a flow of hydraulic fluid in a hydraulic arrangement. The method may include the step of configuring the hydraulic arrangement to allow a flow of hydraulic fluid associated with an upward displacement of the float, thereby allowing the float to be lifted by the wave and inhibiting a flow of hydraulic fluid associated with a lowering of the float, thereby retaining the float at a lifted position.

The method may comprise the further step of providing a positive flow of hydraulic fluid to lift the float from a lifted position to a final lifted position.

In accordance with a sixth configuration, there is provided an electricity generating system, comprising: an elongate pile fixed to a bed of a body of water; a support structure for supporting the pile relative to a bed of the body of water, wherein the support structure comprises: at least a first ring member for receiving the elongate structure in use; a first leg extending between the bed of the body of water and the at least first ring member; and a second leg extending between the bed of the body of water and the at least first ring member, wherein the first and second legs are arranged in a push-pull configuration.

The first ring member may take the form of alternative forms of connecting arrangements between the first and second legs and the elongate pile. BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a perspective view of a wave driven electricity generating system in accordance with the invention, in which piston arrangements are configured in a second and preferred configuration, and wherein an elongate structure of said wave generating system forms part of a conventional offshore wind turbine;

Figure 2 shows a perspective view of a wave driven electricity generating system in accordance with the invention, in which piston arrangements are configured in a first configuration, and wherein the elongate structure of said wave generating system again forms part of a conventional offshore wind turbine;

Figure 3 shows a perspective view of an alternative embodiment of the system of Figure 2;

Figure 4 shows a perspective view of the system of Figure 1 , in which a float forming part of the system is shown in broken lines to reveal details of a fixing arrangement of the system, and wherein degrees of freedom are schematically indicated by arrows;

Figure 5 shows a perspective view of the system of Figure 3, in which the float is again shown in broken lines to reveal details of a fixing arrangement of the system, and wherein degrees of freedom are again schematically indicated by arrows;

Figure 6 shows an assembly comprising the float, the fixing arrangement and secondary piston arrangements of the system of Figure 2, the float shown in section better to illustrate interaction between the various components;

Figure 7 shows a partial side view of the system of Figure 1 , the float shown in section better to illustrate interaction between the various components, and wherein an alternative position of the float is indicated in broken lines to illustrate articulation or displacement of the float in a second degree of freedom;

Figure 8 shows a partial side view of the embodiment of Figure 1 , the float shown in section better to illustrate interaction between the various components, wherein an alternative position of the float is indicated in broken lines to illustrate articulation or displacement of the float in the second degree of freedom, and wherein primary mounts are extended to provide for more vertical orientation of the primary piston arrangements in use;

Figure 9 shows a top view of the system of Figure 1 , in which the float is substantially ringshaped, in which detail of a nacelle and wind turbine are omitted;

Figure 10 shows a top view of the system of Figure 1 , in which the float is substantially octagonal, in which detail of a nacelle and wind turbine are omitted;

Figure 11 shows a side view of the system of Figure 1 ; Figure 12 shows a side view of an alternative embodiment of the system of Figure 1 , wherein a base portion takes the form of a lattice or jacket structure;

Figure 13 shows a further alternative embodiment of the system of Figure 1 ;

Figure 14 shows a sectioned side view of the float of the system of Figure 1 , in which details of an internal compartment is shown ;

Figure 15 shows a side view of an alternative embodiment of the system of Figure 1 , including a current driven electricity generating system, and a compartment extending from the elongate structure, for acting as a “machine room” and/or a maintenance workshop space;

Figure 16 shows a side view of an alternative embodiment of the system of Figure 1 ;

Figure 17 shows a sectioned side view of the float of the system of Figure 1 , in which details of alternative example forms of energy transfer devices are shown;

Figure 18 shows the sectioned side view of the float of Figure 18, having pivoted along the first axis;

Figure 19 shows a detailed view of an example embodiment of a current energy generating system incorporated into a monopile, in accordance with the invention;

Figure 20 shows a sectioned top view through the monopile of Figure 19;

Figure 21 shows a detailed front view of a marine turbine forming part of the current generating system of Figure 19;

Figure 22 shows a further detailed front view of a marine turbine forming part of the current generating system of Figure 19;

Figure 23 shows a sectioned top view of a monopile of an alternative embodiment of the current generating system according to the invention, in which the monopile is reinforced with an internal brace and reinforcing collars;

Figure 24 shows a partial exploded perspective view of the monopile of the alternative example embodiment of Figure 23;

Figure 25 shows a sectioned side view of the current generating system of Figure 23;

Figure 26 shows a partial sectioned side view of an auxiliary power generating system in accordance with the invention;

Figure 27 shows a support structure according to the invention, with which a monopile structure may be supported in use;

Figure 28 shows a perspective view of the support structure of figure 27;

Figure 29 shows a sectioned top view of a functional portion (shown by reference numeral 24) of an elongate structure of the system of Figure 1 , wherein the elongate structure has a shape of a regular polygon having 16 sides; Figure 30 shows a sectioned top view of a functional portion (shown by reference numeral 24) of an elongate structure of the system of Figure 1 , wherein the elongate structure has a shape of a regular polygon having 8 sides;

Figure 31 shows side view of a prior art hybrid electricity generating system incorporating a float fixed to a mast, the float having a single, vertical translational degree of freedom;

Figure 32 shows top view of a prior art hybrid electricity generating system incorporating two separate floats fixed to a mast by way of articulating arms;

Figure 33 shows a top view of a horizontal catchment area of the system of Figure 1 ;

Figure 34 shows a top view of a horizontal catchment area of a hypothetical system incorporating six individual floats supported by a mast by means of articulating arms, in which the six individual floats displace a combined volume similar to that of the float of Figure 33;

Figure 35 shows a partial side view of an alternative support structure in use and in accordance with the invention, with which a monopile may be supported, the support structure being provided with legs that are configured in a push-pull configuration; and

Figure 36 shows a perspective view of the support structure of Figure 35.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted", "connected", "engaged" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings and are thus intended to include direct connections between two members without any other members interposed there between and indirect connections between members in which one or more other members are interposed there between. Further, "connected" and "engaged" are not restricted to physical or mechanical connections or couplings. Additionally, the words "lower", "upper", "upward", "down" and "downward" designate directions in the drawings to which reference is made. The terminology includes the words specifically mentioned above, derivatives thereof, and words or similar import. It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," and any singular use of any word, include plural referents unless expressly and unequivocally limited to one referent. As used herein, the term “include” and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a hybrid electricity producing or generating arrangement or system (or “system”) in accordance with the invention is generally indicated by reference numeral 10.

As is discussed in more detail below, the system 10 typically comprises various sub-systems, such as a sub-system provided for generating and/or converting energy/electricity from waves (hereinafter a “wave generating system” 12), a sub-system provided for generating energy/electricity from currents (hereinafter a “current generating system” 14). It will be understood that, even though the present disclosure refers to all the sub-systems as forming an integral part of the system 10, the sub-systems may also function independently from each other, as stand-alone systems, or in various combinations with each other, or alternative systems and subsystems. The present disclosure, although not necessarily discussing such stand-alone systems in detail, extends to and incorporates such stand-alone systems.

The system 10 comprises an elongate structure 18 which extends above a water surface 20 of a body of water 22. As will become apparent from the discussion which follows, the elongate structure 18 needs to be elongate to allow the different sub-systems to function as described. That said, portions of the structure 18 which are not associated with the sub-systems, such as (in some cases as discussed below) a base portion, need not necessarily be elongate.

Generally, a functional portion 24 (also associated with a “transition piece”) (which is best indicated in figure 11 , 12 and 13) of the elongate structure 18, has a substantially constant crosssection, and is in some example embodiments, cylindrical. The functional portion 24 may also have a regular polygonal cross-section (as shown in figures 29 and 30). That said, for the length of the functional portion 24, the regular polygonal cross-section remains substantially constant. For example, the regular polygonal cross-section may have 4, 5, 6, 7 or preferably 8 sides. In the example of figure 29, the cross-section comprises 16 sides. Any feasible number of sides are therefore considered included in the present disclosure. Furthermore, in some cases, the crosssection may be polygonal, while not all the sides are of equal length. The functional portion 24 extends roughly 8 meters below a nominal water level 26 and roughly 16 meters above the nominal water level 26. It will be appreciated that the overall length of the functional portion 24, and the amount it extends above and below the nominal water level 26 may vary according to functional requirements. Throughout this disclosure the “nominal water level” will be taken to refer to an average level of the water surface 20 of the body of water 22, taking into account fluctuations caused by waves, tides, seasonal changes, and the like. It will be understood that the functional portion 24 of the elongate structure 18 is determined or defined based on the specific body of water 22 and the specific design and operation of the sub-systems, as discussed in more detail below.

In some of the examples shown in the figures, such as figures 1 to 3 and 1 1 , the elongate structure 18 comprises a mast, tower, or pile of a conventional offshore wind turbine 28. Throughout this disclosure, references to a mast, tower, or pile will be taken to refer to the elongate structure 18 when forming part of a wind-tower. Certain advantages of using a mast of a conventional wind turbine 28 as the elongate structure 18, specifically as a structure for the wave generating system 12, will become apparent from what follows. These include advantages to the system 10, but also advantages to the operation or efficiency of the wind turbine 28.

The conventional wind turbines 28 referred to herein comprise a nacelle 30, housing certain hardware (not shown), a plurality of turbine blades 32 fixed to the hardware housed by the nacelle 30, via a rotor (not shown), and a tower 34 supporting the nacelle 30. The tower 34 is fixed to the bed 36 of the body of water 22 by being anchored therein by means of a foundation or footing 38. As shown in some of the embodiments, the elongate structure 18 of the system 10, may therefore form an integral part of, or may be defined by, the tower 34. In some embodiments, the tower comprises a mono-pile structure, alternatively an open-lattice or jacket structure or a combination thereof.

Towers 34 extending from bases floating below the surface of the body of water 22 are also known, though not further discussed herein.

It will be appreciated that the conventional wind turbines 28 referred to herein in relation to the wave generating system 12, are specifically offshore wind turbines 28, and do not include land- based wind turbines.

Typically, the wind turbines 28 are located relatively close to the shore in windy areas, and in areas where the depth of the water body 22 (in other words, the distance between the bed 36 and the nominal water level 26, is 60 m or less). It is believed that advances in the construction of tower structures may allow feasible use of the towers in areas where the depth of the body of water 22 exceeds 60m. It is believed that base portions 40 as discussed below (but not limited thereto), may potentially provide such advances in the construction of the tower structures. Throughout this disclosure, a portion of the tower 34 which extends below the functional portion 24 is referred to as the base portion 40. As indicated in the figures and as discussed below, the base portion 40 may take various forms.

The system 10, and in particular the wave generating system 12, furthermore comprises a float 42. The float 42 defines an inner or central cavity 44. The arrangement is such that the elongate structure 18, and particularly, the functional portion 24 of the elongate structure 18, extends through the inner or central cavity 44. The float 42 is therefore arranged about the elongate structure 18.

Generally, the float 42 is arranged so as to extend around at least a portion, such as a portion at least more than 50% of the periphery of the elongate structure 18. However, in the preferred embodiment as shown in the figures, the float 42 extends completely around the elongate structure 18, such that it surrounds the elongate structure 18 completely. The float 42 is therefore substantially ring-shaped when viewed from above, and as best shown in figure 9. That said, and as shown best in figure 10, the float 42 may furthermore take on the shape of a regular polygon (such as the octagon shown in figure 10). It will be appreciated that the shape of the float 42 being a regular polygon is not limited by the number of equilateral sides it has and may therefore for example have three or more sides.

It will be appreciated that the float 42 being ring-shaped means that electricity can be generated (as discussed more fully below) from waves approaching the float 42 from any direction , without negatively impacting on the efficiency of the wave generating system 12. Also, in the case of the shape of the float 42 being polygonal, the higher the number of equilateral sides, the more effective the float 42 will be from this point of view. Furthermore, due to the shape and the multiaxis movement of the float 42 as discussed, there is no need for the float to be rotationally (about the elongate structure 18) brought into alignment with oncoming waves. It will furthermore be appreciated that the ability to generate electricity from waves irrespective of the direction of travel of the waves, is facilitated by the make-up of the system, and particularly, the construction of the fixing arrangement 46 discussed below.

The float 42 is fixed relative to the elongate structure 18 by means of a connecting or fixing arrangement 46, which, as is discussed in more detail below, allows displacement of the float 42 relative to the elongate structure 18. Therefore, passing waves cause the float 42 to be displaced relative to the elongate structure 18. At least one, but typically two or more piston arrangements are provided between the elongate structure 18 and the float 42 (the piston arrangements are and the way in which they are arranged are discussed more fully below). The movement of the float 42 relative to the elongate structure 18 causes the pistons to reciprocate inward and outward causing the piston to suck and pressurise hydraulic fluid in a hydraulic fluid circuit, thereby causing a flow of the hydraulic fluid in the hydraulic fluid circuit 48.

The hydraulic fluid circuit 48 includes hydraulic fluid lines 50, an accumulator 52 and a hydraulic motor/pump unit 54. The hydraulic motor/pump unit 54 is therefore driven by a flow of high- pressure fluid from the accumulator 52 or hydraulic fluid lines 50. The hydraulic motor/pump unit 54 in turn drives an alternator 56, which generates electricity. It will be understood that surplus high pressure hydraulic fluid may be stored in the accumulator. Furthermore, due to the cyclic nature of waves, the provision of high-pressure hydraulic fluid by the piston arrangement(s) is not constant. The accumulator may therefore be used to ensure a smoother or more constant supply of hydraulic fluid to the motor/pump unit 54. Also, it will be appreciated that the more complex the displacement of the float (“complex” in this sense refers to the number of degrees of freedom (“DOF”) about or within which the float is able to be displaced, pivoted, or rotated, and the larger number of hydraulic piston arrangements provided, the more even and constant the provision of hydraulic fluid will be. It is therefore believed that smaller “rocking” or “bobbing” movements (about rotational DOF) of the balanced float around the centrally placed mast structure contributes to the even or more constant provision of hydraulic fluid with minimal losses. Also, it will be appreciated that the second and third (rotational) DOF which allow the float 42 to rock or bob from side to side, means that hydraulic fluid can be pumped with minimal resistance and an improved response time from the balanced float, and therefore, electricity can be generated efficiently, even from fairly small waves and in cases where the vertical displacement of the float 42 is small or even negligible. It will be appreciated that this is not possible or as efficient in the case of a ringshaped float which is allowed purely axial vertical displacement relative to the elongate structure 18. The rocking of the float 42 ensures that a vertical force acting on the float 42 from the waves and causing same to be displaced vertically upwards, moves closer to the tower, thereby reducing any moment caused by such vertical force. Therefore, the potential for pinching is reduced, resulting in lower stress, friction and losses when compared to the prior art.

Further hardware, such as relief valves, hydraulic fluid storage tanks 51 , control circuits and programmable logic controllers (PLCs) and the like, all of which known in the art, are also provided.

With reference to figure 14, fluid lines or ports designated by reference numeral 50.1 designate fluid lines or ports from or through which hydraulic fluid is drawn into piston arrangements (whether primary and/or secondary piston arrangements (76, 82)), whereas fluid lines or ports designated by reference numeral 50.2 designate fluid lines or ports through which high pressure hydraulic fluid is received from the piston arrangements (whether primary and/or secondary piston arrangements (76, 82)).

The fixing arrangement 46 is best shown in figures 4 to 10 and plays a vital role in allowing the float to be displaced in the various DOF as discussed. The fixing arrangement 46 comprises a main body 58 in the form of a collar or sleeve which extends around the elongate structure 18, and specifically, around the functional portion 24. It will be appreciated that the collar or sleeve has an outer shape which is similar to that of the functional portion 24 (circular, polygonal etc). The main body 58 acts as a linear bearing, for guiding the fixing arrangement 46 axially along the elongate structure 18. The main body or collar 58 may be provided with a number of rollers (not shown) or wheels which are urged against an outer surface of the functional portion 24 of the elongate structure 18 and which are fixed to the collar through bearings. Alternatively, low friction slides may be provided. The rollers or slides are provided for reducing friction between the fixing arrangement 46 and the elongate structure 18, when the fixing arrangement 46 is displaced axially. Alternatively, bearing plates from low friction material, or alternative friction limiting bearing arrangements known in the art may be utilised to reduce friction between the main body 58 and the elongate structure 18 during relative axial displacement.

In the case where the cross-section of the functional portion 24 is that of a polygon or regular polygon (as shown in figures 29 and 30), the slides, wheels or rollers associated with the collar may run on “tracks” formed by substantially planar surfaces of the functional portion 24. This will inhibit rotation of the float 42 about a vertical axis along the elongate structure 18. Such rotation should ideally be inhibited to prevent damage to the piston arrangements. Alternatively, or in addition, axially extending tracks or guides (not shown) may be provided with which the collar, slides, wheels, or rollers may interact, to inhibit such rotation of the float 42 about the vertical axis.

The fixing arrangement 46 therefore facilitates the displacement of the float 42 in a first degree of freedom (shown schematically by the arrow 60), namely a substantially axial vertical or axial (relative to the elongate structure 18) displacement.

However, it will be appreciated that, if the float is to follow a wave as it passes, the float will naturally tend to describe a multi-degree of freedom movement. The applicant believes that providing the float with rotational degrees of freedom will allow the float more naturally to be displaced by the wave. Furthermore, the rotation or pivoting of the float has the potential of causing a larger volume of hydraulic fluid to be displaced, reduces losses due to improper alignment of the float relative to the direction of travel of the wave, and, importantly, reduces bending forces and stresses which would otherwise be transmitted via the main body 58 to the elongate structure 18. Furthermore, the additional degrees of freedom also reduce stresses transferred to the elongate structure 18 by the hydraulic piston arrangements.

Therefore, the fixing arrangement 46 is specifically adapted or designed to allow the float 42 to be displaced relative to the elongate structure 18, in a second degree of freedom (shown schematically by the arrow 62), which is a first rotational degree of freedom, and in a third degree of freedom (shown schematically by the arrow 64), which is a second rotational degree of freedom. The first, second and third degrees of freedom (60, 62, 64) are schematically shown in figure 4.

When the float 42 is displaced within or along the second degree of freedom, the float 42 pivots about a first axis 66, which extends substantially horizontally. When the float 42 is displaced within or along the third degree of freedom, the float 42 pivots about a second axis 68, which extends substantially horizontally, and substantially perpendicularly to the first axis 66.

The fixing arrangement 46 includes an intermediate body 70. A first pivot 72 is provided between the main body or collar 58 and the intermediate body 70, so that the intermediate body 70 is allowed to pivot about the first axis 66 and therefore, in the first degree of freedom. A second pivot 74 is provided between the intermediate body 70 and the float. The second pivot 74 is mounted perpendicularly to the first pivot 72, and therefore allows the float 42 to pivot about the second axis 68 and therefore in or along the third degree of freedom. It will be appreciated that the size and direction of travel, of a wave passing the elongate structure 18, will determine in which of the first, second and/or third degrees of freedom the float 42 will be displaced. Again, as mentioned, the displacement of the float 42 may be complex, and may therefore typically be in more than one of these degrees of freedom.

The piston arrangements used with the wave generating system 12, may be arranged in various configurations. A first configuration is typically shown in figures 2, 3 and 5, while the second configuration (which is a preferable configuration) is typically shown in figures 1 , 4, 7, 8, 1 1 , 12, 13, 15, 16, and 25.

In the first configuration, at least a first, but typically up to eight or more primary piston arrangements (generally indicated by reference numeral 76, with suffixes denoting individual and separate primary piston arrangements) are provided. The primary piston arrangements 76 are all substantially similar, and therefore it will be appreciated that a discussion in respect of one primary piston arrangement 76 applies equally to all further primary piston arrangements 76. Each primary piston arrangement 76 is mounted between the elongate structure 18 and the main body 58 of the fixing arrangement 46. The primary piston arrangements 76 will therefore reciprocate inward or outward in reaction to displacements of the fixing arrangement 46 and more particularly, the float 42, in the first degree of freedom. The primary piston arrangements 76 therefore reciprocate in reaction to vertical displacements or axial displacements of the float 42 relative to the elongate structure 18.

A first primary mount 78 is provided on the elongate structure 18 for fixing an end of each primary piston arrangement 76 relative to the elongate structure 18. Therefore, the number of first primary mounts 78 will match the number of primary piston arrangements 76.

A second primary mount 80 is provided on the main body 58 of the fixing arrangement 46 for fixing an opposite end of each primary piston arrangement 76 relative to the main body 58 or collar. Therefore, the number of second primary mounts 80 will also match the number of primary piston arrangements 76.

The respective ends of the primary piston arrangements 76 are pivotably fixed to the first and second primary mounts (78, 80) by means of multi-axial pivot connection mechanisms, typically in the form of ball joints or universal joints.

The primary piston arrangements 76 are double acting piston arrangements, which means that hydraulic fluid is located on both sides of a piston body of the primary piston arrangements 76, so that hydraulic fluid can be pumped from a body of the primary piston arrangement, during both an inward and an outward stroke thereof. Various non-return or one-way valves may be provided in the hydraulic circuit to facilitate this.

Furthermore, the primary piston arrangements 76 can also be used to lift the float 42 away from the water surface 20, such as during maintenance or during storms. High pressure hydraulic fluid may therefore be channelled to the primary piston arrangements 76 for this purpose. The hydraulic circuit may be specifically adapted to facilitate this.

Alternatively, instead of, or in addition to (for the purpose of lifting the float from the water), channelling high pressure fluid to the rod side of the primary pistons to lift the float from the water, the various valves may be configured to allow hydraulic fluid to flow from the primary piston arrangements 76 when the waves cause the float 42 to be lifted in an upward direction, but may prevent or inhibit the float from returning in a downward direction, thereby retaining the float at a lifted position. This process may be a stepwise lifting process, by which the passing waves cause the float to be sequentially lifted to a first, second and further lifted position, higher and higher out of the water, and therefore, out of direct danger of the stormy water. After the waves have been utilized to lift the float out of the water (without the need of a pump or an accumulator, therefore, without using auxiliary power), additional hydraulic fluid may be channelled by accumulators and/or a pump into the primary pistons, to lift the float further above the body of water to a final lifted position.

It will be appreciated that the double-acting pistons have a first contact area, on a non-rod side of the piston, which is comparatively large, and a second contact area on the rod side of the piston, which is comparatively small. The larger contact surface is used for positively pumping hydraulic fluid in use, while the smaller contact surface is used when locking the vertical position of the float 42, as mentioned. Therefore, during normal operation of the system 10, hydraulic fluid may flow relatively freely relative to the second contact area. Therefore, the fluid circuit in flow communication with this contact surface is designed with a low backpressure in mind. However, hydraulic fluid is still always required in this circuit, to ensure quick response when the float is locked or retained in position. In this sense, the “locking” or “retaining” of the float will be understood to be a “one directional locking or retaining”. In other words, the float is held and inhibited from moving vertically downwards, whilst still being allowed to be displaced upwards by passing waves.

Therefore, when it comes to the lifting or jacking of the float 42 from the water, three modes of operation are provided for: firstly, under normal operating conditions of the wave generating system, hydraulic fluid may flow relatively freely relative to the second contact area as mentioned; secondly, when the float is intermittently lifted higher out of the water by the passing waves (as discussed) oil is allowed to flow into the piston arrangement as the float is lifted by the waves, but inhibited from flowing therefrom as the wave passes, thereby, retaining the float in the lifted position(s); and thirdly, pressurised oil may be pumped into the piston arrangement (on the rodside) to positively cause the float to be lifted further out of the water.

In the first configuration, at least a first, but typically two (as shown in figure 3) or four (as shown in figure 2) secondary piston arrangements (generally indicated by reference numeral 82, with suffixes denoting individual and separate primary piston arrangements) are provided. As shown, the secondary piston arrangements 82 are provided in pairs, and arranged on opposite sides of the elongate structure 18. The secondary piston arrangements 82 are all substantially similar, and therefore it will be appreciated that a discussion in respect of one secondary piston arrangement 82 applies equally to all further secondary piston arrangements 82. In an embodiment not shown in the figures, only two secondary piston arrangements 82 are provided, and arranged substantially perpendicularly to each other. In this way, the first of the two secondary pistons arrangements 82 is displaced when the float 42 pivots about the first axis 66, and the second of the secondary pistons arrangements 82 is displaced when the float 42 pivots about the second axis 68.

Each secondary piston arrangement 82 is mounted between the main body 58 of the fixing arrangement 46 and the float 42. The secondary piston arrangements 82 will therefore reciprocate inward or outward in reaction to displacements of the float 42, in the second and third degrees of freedom. The secondary piston arrangements 82 therefore reciprocate in reaction to rotational or pivoting displacements of the float 42 relative to the elongate structure 18.

In cases where only two secondary piston arrangements 82 are provided (therefore, only a first pair of secondary piston arrangements 82 are provided, such as shown in figure 1 ) the fixing arrangement 46 facilitates displacement of the float in the second degree of freedom, but not the third degree of freedom as discussed above (the second pivot 74 will therefore not be present). In such cases, the float 42 may be provided with means of aligning itself relative to the direction of the waves or the current (a further rotational degree of freedom about an axis extending lengthwise along the elongate structure 18 will be provided in such a situation, which will not be discussed in further detail).

A first secondary mount 84 is provided on the main body 58 for fixing an end of each secondary piston arrangement 82 relative to the main body 58. Therefore, the number of first secondary mounts 84 will match the number of secondary piston arrangements 82.

A second secondary mount 86 is provided on the float 42 for fixing an opposite end of each secondary piston arrangement 82 relative to the float 42. Therefore, the number of second secondary mounts 86 will also match the number of secondary piston arrangements 82.

The respective ends of the secondary piston arrangements 82 are also pivotably fixed to the first and second secondary mounts (84, 86) by means of multi-axial pivot connection mechanisms, in the form of ball joints, or universal joint type connections. The ball joints further allow and facilitate the multi-axial displacement of the float 42.

The secondary piston arrangements 82 are also double acting piston arrangements. In the second (and preferred) configuration of the piston arrangements (as best shown in figures 1 and 4), the primary piston arrangements 76 extend directly between the elongate structure 18 and the float 42. One advantage of this configuration, is the fact that no secondary piston arrangements will be required, requiring less maintenance and fewer parts.

Now, the primary piston arrangements 76 will reciprocate inward or outward in reaction to displacements of the fixing arrangement 46 and more particularly, the float 42, in the first, second and third degrees of freedom.

The first primary mounts 78 are still provided on the elongate structure 18 for fixing an end of each primary piston arrangement 76 relative to the elongate structure 18, while the second primary mounts 80 are provided on the float 42 for fixing the opposite end of each primary piston arrangement 76 relative to the float 42. Again, the respective ends of the primary piston arrangements 76 are pivotably fixed to the first and second primary mounts (78, 80) by means of multi-axial pivot connection mechanisms, in the form of ball joints.

Each of the primary and secondary piston arrangements (76, 82) has a barrel end 88 and a rod end 90. The orientations of the piston arrangements (76, 82) will be selected based on the location and configuration of the hydraulic circuit.

For example, if the second configuration of piston arrangements are used (as shown in figure 1 ) and the accumulator 52, motor/pump unit 54 and alternator 56 are housed inside the float 42 (as discussed more fully below) the barrel ends 88 of the primary piston arrangements 76 may be fixed to the second primary mounts 80, while the rod ends 90 of the primary piston arrangements 76 will be fixed to the first primary mounts 78. In this way, the fluid lines 50 may be as short as possible and will not have to account for the reciprocation of the primary piston arrangements 76.

Alternatively, if the accumulator 52, motor/pump unit 54 and alternator 56 are housed inside the elongate structure 18 or in a compartment fixed to the elongate structure 18 (as discussed more fully below) the barrel ends 88 of the primary piston arrangements 76 will be fixed to the first primary mounts 78, while the rod ends 90 of the primary piston arrangements 76 will be fixed to second primary mounts 80.

Similar variations are possible for the primary and secondary piston arrangements (76, 82) of the first configuration. As shown best in figure 14, the float 42 may be provided with an internal compartment 92 within which to house the accumulator 52, motor/pump unit 54, alternator 56 and the like. It will be appreciated that an arrangement as shown in figure 14, means that the hydraulic fluid lines and other hardware required for the functioning of the wave generating system 12 are compact and close to the piston arrangements, for improved efficiency.

In an alternative embodiment, as shown typically in figures 15 and 25, a compartment 94 is provided above the first primary mounts 78, and is either mounted to the elongate structure 18, or formed integrally therewith.

The compartment 94 typically functions as an “engine room” and a workshop. Advantages of mounting the accumulator 52, motor/pump unit 54, alternator 56 and the like in the compartment 94, include better shielding the hardware from the elements associated with the body of water 22, providing the hardware on a stationary platform and the ease with which maintenance can be done on the hardware.

As mentioned above, the elongate structure 18 comprises a functional portion 24 and a base portion 40. As shown by reference numeral 96, the functional portion 24 typically extends 8 meters below the nominal water level 26. This is to account for the axial displacement of the fixing arrangement 46 which, uses the functional portion 24 as a guide.

The base portion 40 takes one of various forms. In some cases, such as the example shown in figure 11 when the elongate structure forms part of a conventional wind turbine 28, the base portion 40 is substantially cylindrical, and constitutes an extension of the functional portion 24.

In other cases (such as the examples shown in figures 12, 13, 15,16 and 25), the base portion is formed by a lattice structure. The lattice structure provides additional structural integrity to the base portion, in order better to resist lateral forces caused by the float 42 and its interaction with passing waves.

A bottom outer side portion or surface 98 of the float 42 is bevelled or curved to help absorb some of the forces of waves crashing into the float 42, and to enable the float 42 better to follow the swell of the waves. Furthermore, as is best shown in figure 7, upper and lower inner portions or surfaces (100, 102) of the float 42 are also bevelled, to allow or facilitate pivoting or articulation of the float 42 without interfering with the fixing arrangement 46. It will be appreciated that this shape of the float 42, together with the float surrounding the elongate structure, allows the displaced volume of the float to be large relative to the horizontal catchment area of the float. It is believed that a float of this shape and configuration is associated with a significantly smaller horizontal catchment area than an arrangement comprising of separate floats fixed to a structure by way of articulating arms. This is illustrated in figures 33 and 34 where L1 shows the horizontal catchment area of the float 42, and L2 shows a horizontal catchment area of six floats (with a combined volume of displacement equal to that of the float 42) fixed to the mast by way of articulating arms. Figures 33 and 34 are not necessarily to scale and serve to illustrate conceptually how individual floats arranged in this way has a larger catchment area than a single float.

The size, volume and mass of the float is all determined based on factors such as the size and mass of the elongate structure 18 or wind turbine 28, the amount of electricity to be generated and the like. It is foreseen that the float 42 may typically have a volume and a mass which are functions of, amongst others, the total weight of the wind turbine 28. It is foreseen that the volume and the mass of the float 42 will be selected so that the net force transferred to the elongate structure 18 because of the buoyancy of the float, and the passing waves, will not cause damage or instability to the wind turbine.

It is believed that the net force so transferred to the elongate structure 18, typically needs to be limited to between 60% and 90% of the total weight of the wind turbine. For example, in cases where the wind turbine 28 has a weight of 1500 metric tonnes, the float may be selected to have a volume capable of displacing 900 to 1350 metric tonnes of water. However, this net force may typically be increased in cases where the anchoring of the wind turbine 28 in the bed 36 allows for same. Additional anchoring mechanisms such as improved foundation or footing structures, anchor cables and the like, may be used for this purpose. It will be appreciated that improved anchoring of the pile in the bed 36 may increase the permissible amount of force transferred to the elongate structure 18 beyond what is mentioned above.

It will be appreciated that the net force transferred to the elongate structure 18 is a function of the volume of water displaced by the float 42, minus the mass of the float 42. Furthermore, an increased mass of the float 42 increases the volume and/or pressure of the hydraulic fluid that can be pumped on the downstroke of the float 42. However, increasing the mass of the float 42, as a negative impact on the volume and/or pressure of the hydraulic fluid that can be pumped on the up-stroke of the float 42. On the other hand, increasing the volume of the float 42 increases the volume of water displaced by the float by a passing wave, and again increases the volume and/or pressure of the hydraulic fluid that can be pumped on the up-stroke of the float 42. Ultimately, the above factors are used in a determination of an optimal float 42 size and mass. The current generating system 14 is now discussed in more detail. The current generating system 14 can take various forms, depending on the structure of the base portion 40. Figure 15 shows the current generating system in a first embodiment, where the base portion 40 takes the form of a lattice or “Jacket” structure. The current generating system comprises at least a first, but typically more than one marine turbine assembly (generally referred to by reference numeral 104 with suffixes denoting separate, independent but similar turbine assemblies).

The marine turbine assemblies 104 are mounted to a mounting structure 106 or trolley, which is vertically displaceable relative to the base portion 40. As shown in the figures, the base portion 40 now typically defines an axially extending column in which the mounting structure can be displaced. The mounting structure 106 can rotate about an axis extending along a length of the base portion 40, so as to align the turbine assemblies with underwater currents. Alternatively, each marine turbine assembly 104 is configured to rotate independently relative to the mounting structure 106 and about the axis extending along the base portion. The marine turbine assemblies 104 are therefore driven by passing currents, thereby generating electricity in known fashion.

A pulley 108 may be provided at a bottom of the base portion 40, around which a cable 1 10 is wound, which cable 1 10 is fixed to the mounting structure 106. A winch 112 is mounted to the elongate structure 18 at a location above the water surface 20, and typically above the compartment (if relevant). The winch 112 is used to displace the mounting structure 106 vertically and can be used to provide the marine turbine assemblies 104 in a vertical position with the highest current flow rates. The whole mounting structure 106 can be removed from the water by the winch system 112, to enable maintenance or cleaning to be undertaken on the marine turbine assemblies 104 or the mounting structure 106. The mounting structure 106 is hoisted into the compartment 94 for this purpose. In this way, the which 112 removes the need for underwater repairs undertaken by divers, or manual underwater removal of the turbines, and therefore alleviates a problem of known marine turbine systems. The elongate structure, or at least the functional portion 24, may therefore act as an elevator shaft or column 114 within which the mounting structure 106 may be hoisted. The compartment 94 may be open to the elevator shaft 1 14, to allow for easy maintenance of the marine turbine assemblies 104.

Guide members 115 are provided in the elevator shaft 1 14 and also the base portion 40, for guiding the mounting structure 106. The mounting structure 106 is in turn fitted with contact members, in the form of rollers, or bearing plates (not shown) provided for contacting with the guide members 115 and guiding the mounting structure 106 when same is displaced relative to the guide members 1 15. A bottom end 1 16 of the functional portion 24 may therefore be open and the mounting structure 106 may be hoisted into and from the elevator shaft 114, through the open bottom end 116.

It will be understood that sides of the bottom portion 40 are open, to allow underwater currents to flow relative to the marine turbines assemblies 104, thereby driving the marine turbine assemblies 104.

Figures 19 to 27 show alternative embodiments of the current generating system 14. Here, the base portion takes the form of a monopile structure.

The marine turbine assemblies 104 are received within the base portion 40 in the form of a monopile. Therefore, openings 140 are formed in the sidewall of the pile. Each turbine assembly 104 is associated with a set of opposing openings 140. A respective flow channel 142 is defined through the pile and between the openings 140 of each set. The turbine 104 is therefore, in use, received within the flow channel 142 where it is supported by a hydro-dynamically shaped support 160, and in fluid flow communication with the body of water, where same is driven, by an underwater current.

It will be appreciated that, generally, creating openings in the side walls of the pile would not be advisable, since this may have a weakening effect on the pile. However, provision is made for reinforcing the pile, specifically proximate the openings.

In one of the alternative embodiments, shown in figures 19 to 22, the marine assemblies are fixed relative to the pile. The reinforcement now takes the form of a tubular member 144 which extends across the pile between the openings 140. Typically, the tubular member 144 is welded into position.

Since the turbines are fixed in position, maintenance needs to be undertaken while the turbines are submersed in the body of water. For this purpose, doors 146 are provided with which the openings 140 may be closed and sealed from the body of water. Once the doors are closed, water within the flow channel 142 may be pumped out. An access hatch 148 which connects the inside of a maintenance or access column 156 to the flow channel 142 allows maintenance personnel access to the turbine 104. Naturally, the access hatch 148 is closed and sealed, and the doors 146 are open, when the turbine 104 is operational.

In a further, and preferred embodiment of the current generating system, shown in figures 23 to 25, each opening 140 is associated with a reinforcing collar 150, which extends into, but not across, the pile. This embodiment therefore does not include the tubular members 144. Again, the collars 150 are welded in position. Furthermore, an axially extending internal brace member or column, typically in the form of a square, rectangular or circular brace member 152 is provided to provide further stability and strength to the pile. The brace member 152 may be welded to an inner surface of the pile (typically, at locations indicated by numeral 154).

The brace is also associated with openings in the side, which are aligned with the openings 140 through the pile, such that a flow channel is still defined through the pile. The reinforcing collar typically extends to the brace 132.

The brace member 152 also defines an axially extending, and therefore substantially vertical, column 114, as well as a maintenance or access column 156. So-called “J-tubes” 200 run next to or within the access column 156. Again, the turbines may now be mounted to a mounting structure 106, which is displaceable within the column 114, between an operative position where the turbines are situated within flow channels, and inoperative positions where the turbines are hoisted out of the body of water, to allow maintenance to be carried out, typically in the compartment 94. A counterweight 202 is provided for assisting with hoisting of the mounting structure. A weight of the counterweight 202 may typically be around 75% of that of the mounting structure 106 and the turbines. The counterweight is fixed, over a sprocket or pulley arrangement 204, to the mounting structure 106, by means of a chain or rope 206. In use, the counterweight moves along a longitudinally extending cavity 208, which is defined between an inner surface of the pile 40 and the brace. The sprocket arrangement 204, or at least one of the sprockets forming part of the sprocket arrangement, is driven, in use, by a motor with a gearbox, such as a planetary gearbox (the motor and gearbox are collectively indicated by numeral 210.

It will be appreciated that the reinforcements provided facilitate providing the openings 140 in the pile, which would otherwise not be possible. The applicant furthermore believes that the openings 140 reduces the frontal area of the pile, thereby reducing a load transferred by the current on the pile. Furthermore, generally, monopiles are preferred as base portions 40, due to their relative ease and cost efficiency of installation, compared to lattice or Jacket structures. It is foreseen that integration of the current generating arrangement 14 into the monopile would still allow the monopile to be installed according to usual techniques.

It is believed that the current generating system 14, for example, when installed in a 10 MW wind tower installed in an aera with an approximate water depth of 60 meters, and the system 14 includes an array of between 6 and 10 turbine assemblies spaced vertically (with approximately 1 to 1 .5 meter spacing between turbine assemblies), each having an outer blade diameter of approximately 6 meters, could produce up to 0.8 MW to 1 MW of additional electricity. This electricity would also be available additionally to the electricity generated by the wind tower, but importantly and advantageously, will also be available during times of inclimate weather, which forces other electricity generating systems, such as the wind and wave generator, to be immobilised. The current generator system 14 may therefore also supply a source of auxiliary power to on-board equipment, which will be available when other electricity generating systems are not.

As shown in figure 16, marine turbine assemblies 104 may also be mounted to the bottom of the float 42, to increase the amount of electricity generated from water currents flowing relative to the system 10. Beneficially, the fluid lines associated with these turbine assemblies may be fairly short (especially in cases where hardware is located inside the internal compartment 92), due to their proximity to the float 42. These turbine assemblies may be substituted with alternative known devices which may be utilised to generate electricity from passing currents. It will be appreciated that the proximity of these devices to the float 42, which follows the swells and waves as they move past the float 42, means that the devices will always be located at a relatively constant depth relative to the nominal water level 26.

It will be understood that the marine turbine assemblies 104 may be of the known kind and may have fixed- or variable-pitch blades, may have two or more radial blades, may have a centrally mounted hub or a rim-mounted hub and the like.

The system 10 may include an auxiliary power generating system 300, best shown in figure 26. It will be appreciated that the inside of the monopile, extending above the surface 20 of the body of water 22, is typically filled with air, whereas, in most cases, the inside of the monopile extending below the surface 20 of the body of water 22, is filled with water. In the case of the use of an auxiliary power generating system 300, an opening 302 is again provided in the pile (below the surface of the body of water), which allows a water level 304 within the pile to rise and fall with the swells of the body of water 22. Channels 410 are provided from the opening 302 to the inside of the pile to allow water to flow into the pile. Therefore, an oscillating water column 306 may be present within the pile. Now, a low-pressure air turbine 308 is installed in the pile, such that in use, the low-pressure air turbine 308 is located above the water surface 304 inside the pile. The low-pressure air turbine 308 typically takes the form of a multi-directional air turbine, which is driven in one rotational direction, irrespective of the direction of flow of air. Air displaced by the oscillating water column 306 therefore drives the low-pressure air turbine 308.

The low-pressure air turbine 308 is mounted to a disc-shaped base 310. The base 310, in turn, is mounted to an extension rod 412 which extends from the mounting structure 106. An adjustment mechanism (not shown) is provided for adjusting a vertical position or height of the base 310 relative to the extension rod 412, and therefore, relative to the water level 304. It will be appreciated that a vertical position of the base 310 is determined, based among others, on an amplitude of the swells of the oscillating water column 306. By adjustment of the base 310, the pressure of air between the base 310 and the level 304 may be optimised with the operation of the turbine 308 in mind (without necessarily adjusting a vertical position of the mounting structure 106). A diverter plate 312 is provided for diverting a hang-off cable, to inhibit interference between the base 310 and the hang-off cable when the base 310 is vertically adjusted.

Since air is compressible a “cushioning effect” is present, even in cases of severe swells associated with inclimate weather. Therefore, again, the auxiliary power generating system continues producing electricity, to keep vital systems functional, even when other main electricity producing systems are shut down.

It is foreseen that a further inlet/outlet for air to and from the inside of the pile will be provided to provide for the flow of air caused by the oscillating water column within the pile. Furthermore, the inlet/outlet may be provided with a control valve, such as a gate valve, with which the flow of air can be regulated.

In some embodiments (not shown), more than one turbine 308 may be provided. In such cases, the more than one turbines 308 may be smaller, or may have different sizes, to accommodate situations in which oscillations of the water column 306 are smaller, and not necessarily enough to drive a larger turbine. Also, the multi-directional turbine may be replaced by more than one one-directional turbine, associated with one-way valves and the like, to allow for being driven by air flow in more than one direction.

It is believed that in some cases (such as for example in the case of a 10 MW tower), the low- pressure turbine may produce between 35 kW and 50 kW of auxiliary power.

It is believed that the auxiliary power generating system may obviate the need for an auxiliary power cable or on-board power generation by means of fossil fuel generators.

It will be appreciated that the auxiliary power generating system 300 may find application with wind towers of the known kind, without integrated wave generating systems or current generating systems. Figures 27 and 28 shows a support structure according to the invention, with which a monopile structure is supported in use. In use, the monopile will be piled into the bed 36 of the body of water, in known fashion. Thereafter, the support structure, comprising at least a first and second ring member (180, 182) slides over the monopile, until a footing 188, makes contact with the bed 36. First and second legs (184, 186) extend between the footings 188 and the first and second ring members (180, 182). The footings 188 are anchored to the bed and may comprise hydraulic members (not shown) which may exert a downward force on and anchor into the bed.

The rings may be locked relative to the pile, by way of a ratchet-type fixing arrangement (not shown) or other types of fixtures, such as welding, rivets, bolts, and the like.

It is believed that the support structure could provide additional support to a monopile structure, to assist in withstanding lateral forces exerted on the monopile by tides, the float 42, wave loads and the like. Furthermore, it is believed that the advantages of monopiles, namely the ease and cost effectiveness of installation may be retained. It is foreseen that the support structure could be manufactured off-site and simply installed by relatively easily being lifted over the installed monopile foundation fixed in the seabed.

It is also believed that the use of the support structure facilitates use of the monopile in areas where the depth of the body of water could exceed 60 meters.

The support structure may in some examples, comprise three sets of first and second legs (184, 186), or as shown in the figures, may comprise four sets of first and second legs (184, 186).

In another example, which is shown in figures 35 and 36, the first ring member 180 may be associated with two first legs 184 only. The first legs may now extend from two footings 188 to the first ring 180 and may converge towards one another in the direction of the first ring member 180. At the same time the first legs 184 may define an acute angle relative to the bed, and may therefore, slant forwards towards the first ring member 180. Viewed in plan , an angle between the first legs 184 is smaller than 180 degrees. The first legs are also configured to be able to withstand predetermined tensile loads without shearing as well as predetermined compressive loads without buckling. Therefore, the configuration comprises two adjoining legs 184 and the first ring member 180. This configuration of the legs will, for the purpose of this disclosure, be termed a “push-pull” configuration. Each footing 188 is fixed to the bed, typically by way of a pile 190 extending into the bed or other suitable mounting or anchoring structures. It will readily be appreciated that the second ring member 182 may also be configured in a similar push-pull configuration, which will include the second ring member 182, and two of the four second legs 186, as shown.

As shown in figures 35 and 36, a combination of two ring members (180, 182) and two sets of legs, each set of legs provided in a push-pull configuration is also provided for.

It will be appreciated that configuring the legs in a push-pull configuration means that the support structure is made up of fewer structural components, which results in a more cost-effective structure, which is easier to manufacture, easier to transport, and easier to install.

It will be appreciated that the system 10, and the subsystems pose various advantages to known systems of this kind.

Specifically, it is believed that the energy efficiency, energy density and the total amount of electricity generated by the system may be improved when utilising the various electricity generating components or subsystems of the system in parallel. It is believed that this may make such electricity generating systems utilising natural or sustainable resources more viable.

With specific reference to the wave generating system 12, utilising a substantially ring-shaped float 42 means that the direction of travel of the waves do not negatively impact on the efficiency of the generation of electricity by the system. The three degrees of freedom of the float 42, as well as the configuration of the fixing arrangement 46 also contribute to this. Furthermore, due to shape of the float 42, same can be mounted and retrofitted to existing structures, such as existing wind turbines 28. Also, it is believed that, due to the range of motion of the float 42 (namely displacement in the three degrees of freedom), the float 42 better follows the motion of the passing waves, and therefore, electricity can more efficiently be generated. Additionally, due to at least the relative size of the horizontal catchment area, as well as the rotational degrees of freedom of the float, stresses transferred to the elongate structure 18 are minimised. Particularly, bending stresses or moments transferred to the elongate structure 18 are minimised or even substantially eliminated.

Furthermore, the float 42 and the fixing arrangement 46 provide a very compact layout of the wave generating system 12. Known wave generating systems have elongate “arms” with various pivot points. The moments created about the pivot points of these arms are substantial, increasing manufacturing and maintenance costs. The fixing arrangement 46 and the fact that the elongate structure 18 extends through the central cavity 44 reduce the moment arms associated with the system 12.

The applicant furthermore believes that expenses associated with known wind towers, such as the expenses associated with the tower, the installation and piling thereof into the subsea bed, and the installation of subsea cables, can be diluted by the addition of electricity generating, and harvesting arrangements and systems, as described herein.

Initial estimates and calculations lead the applicant to reasonably believe that that the electricity generated by a wind turbine of the known kind, may potentially be increased by as much as 50% by the addition of the electricity generating, and harvesting arrangements and systems, as described herein. It is also believed that this may result in a reduction of the unit asset cost per megawatt of generating capacity, of between 15% and 20%.

It is therefore believed that a unit cost of electricity generated by the system incorporating a wind turbine, the wave generating system 12, the current generating system 14 will be lower than the unit cost of electricity generated by conventional wind turbines.

It is also believed that the wave generating system 12 and the current generating system 14 do not contribute significantly to so-called “visual pollution” already associated with a wind turbine of the known kind, since structures already provided as part of the wind turbine of the known kind are used to facilitate the use of the wave generating system 12 and the current generating system 14. It is believed that the additional electricity generating capacity or capability of such a system, without the addition of visual pollution, is beneficial.

The hybrid nature of the system described herein furthermore removes the strict dependency on one specific source of renewable energy, and therefore provides a means of smoothing electricity generated by the overall system. For example, in times where low winds are experienced, waves and sub-sea currents typically still exist (even though these may also be impacted by winds, though not as drastically), and the hybrid system can still generate electricity. Furthermore, tidal currents are highly predictable, reliable, and unaffected by weather conditions, such as winds.

It will be appreciated that the above description only provides some example embodiments of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention. For example, in at least some instances, the hydraulic cylinder arrangements could potentially be replaced with alternative linear energy transfer devices, even though these are not shown or discussed in detail. This is particularly true (but not limited to) the primary piston arrangements 76. Examples of such alternative linear energy transfer devices may include rack-and-pinion arrangements (in which the pinion is fixed to the shaft of a hydraulic pump/motor or an electrical alternator/motor unit), linear electromagnetic arrangements (such as used in Maglev trains or rollercoaster launch systems)

In another example, hydraulic components as described may be replaced by piston arrangements with integrated accumulators and/or oil tanks and/or alternator units and the like. It will be appreciated that such integrated components may reduce complexity of the hydraulic arrangement of the overall system, may ease the maintenance burden and may provide for redundancy of the hydraulic arrangement. Also, fitment of the vital hydraulic and electricity producing components near each other reduces pressure drops, friction and heat, thereby improving efficiency and output.

It will be appreciated that the hydraulic components discussed herein may be configured in parallel, series or as stand-alone components. The hydraulic systems may be configured based on operational requirements, such as required hydraulic pressure, flow rates, storage capabilities, capacities, and the like.

Furthermore, in an alternative embodiment, which is shown in figures 1 7 and 18, the secondary piston arrangements (82.1 to 82.4) are removed and replaced by internal secondary piston arrangements (indicated by reference numeral 82.5). In such an example, the first and second pivots (72, 74) are fitted with extension arms 130, which do not pivot relative to the elongate structure 18 when the float pivots about the respective pivot to which the extension arm 130 is fitted. A first end of the internal secondary piston arrangement 82.5 is therefore fitted to the extension arm, and another end of the internal secondary piston arrangement 82.5 is fitted to a surface of the float 42. Therefore, pivoting of the float 42 relative to the elongate structure 18 actuates the internal secondary piston arrangement 82.5 causing a flow of hydraulic fluid as discussed previously. At least one, but typically two internal piston arrangements 82.5 may be fitted per pivot. The internal secondary piston arrangements 82.5 furthermore take up less space, and are out of the way, in cases where the float 42 needs to be lifted from the water (such as during stormy weather). It will be appreciated that an embodiment comprising one or more secondary pistons (82.1 to 82.4) in combination with one or more internal secondary pistons 82.5 would be feasible. Further alternatively, as also shown in figures 17 and 18, the secondary piston arrangements (82.1 to 82.4) may be removed and replaced by a motor unit 136 fixed to an inner surface of the float 42 and coupled directly to the pivot typically through a gear arrangement (indicated schematically by gears 132 and 134), a pulley and belt arrangement, a sprocket and chain arrangement or the like. It will be understood that the gear 132 fitted to the pivot does not pivot relative to the elongate structure 18 when the float pivots about the respective pivot, while the motor unit 136 will be displaced with the float 42. Interaction between the gear 132 and the gear 134 will therefore cause a shaft of the motor unit to pivot. This may in turn be used to drive a hydraulic pump, or an alternator (not shown).

Also, as shown in figure 7, in some embodiments, the first primary mounts 78 may be fixed to a mount collar 400. The mount collar 400 may be displaceable relative to the elongate structure 18, and may be provided with rollers, wheels, bushes, or slides (not shown), to allow displacement relative to the elongate structure. Further hydraulic piston arrangements may be provided to adjust the vertical position of the mount collar 400. The mount collar may provide for the vertical adjustment of a nominal position of the float 42. It will be appreciated that this may be required in cases where the amplitude of waves exceed the stroke of the primary piston arrangements 76, or during heavy storms and the like.

It will be appreciated that at least some of the pivots may be fitted with motor units 136, or alternatively, all of the pivots may be fitted with internal secondary piston arrangements 82.5, or further alternatively, a combination of motor units 136 and internal secondary piston arrangements 82.5 may be provided.

It will be appreciated that the float need not comprise of a single hollow structure or compartment. For example, the float may take the form of a float assembly, made up of a plurality of smaller, individual floats, interconnected by a frame structure. The float assembly may still define the inner cavity 44 through which the elongate structure 18 may project in use. The arrangement of the float assembly may be such that the individual floats may be interconnected in such a way that relative displacement between the individual floats will be inhibited by the frame structure.

It will easily be understood from the present application that the particular features of the present invention, as generally described and illustrated in the figures, can be arranged, and designed according to a wide variety of different configurations. In this way, the description of the present invention and the related figures are not provided to limit the scope of the invention but simply represent selected embodiments. The skilled person will understand that the technical characteristics of a given embodiment can in fact be combined with characteristics of another embodiment, unless otherwise expressed or it is evident that these characteristics are incompatible. Also, the technical characteristics described in a given embodiment can be isolated from the other characteristics of this embodiment unless otherwise expressed.

Even though the embodiments described and exemplified above, and illustrated in the figures, represent what the applicant views as a most advantageous and/or useful embodiment of the invention, the applicant believes there may yet be advantages associated with alternative embodiments of the invention.

Claims

38

CLAIMS:

1 . An electricity generating system comprising: an elongate structure extending above a water surface of a body of water; a float defining an inner cavity through which the elongate structure extends in use, the arrangement such that the float extends at least 50% around a periphery of the elongate structure; a fixing arrangement for displaceably fixing the float relative to the elongate structure, wherein the fixing arrangement facilitates displacement of the float relative to the elongate structure, in a first and second degree of freedom; and at least a first energy transfer device extending between the float and the elongate structure, which is actuated by displacement of the float relative to the elongate structure.

2. The electricity generating system according to claim 1 , wherein the float surrounds the elongate structure.

3. The electricity generating system according to claim 1 or 2, wherein the first degree of freedom is a translational degree of freedom, and wherein the fixing arrangement facilitates axial displacement of the float relative to the elongate structure.

4. The electricity generating system according to any one of the preceding claims, wherein the second degree of freedom is a first rotational degree of freedom, and wherein the fixing arrangement facilitates rotational/pivoting displacement of the float relative to the elongate structure and about a first axis, which extends substantially horizontally.

5. The electricity generating system according to claim 4, wherein the fixing arrangement facilitates displacement of the float relative to the structure, in a third degree of freedom.

6. The electricity generating system according to claim 5, wherein the third degree of freedom is a second rotational degree of freedom, and wherein the fixing arrangement facilitates rotational/pivoting displacement of the float relative to the elongate structure and about a second axis, which extends substantially horizontally and substantially perpendicularly relative to the first axis.

7. The electricity generating system according to claim 6, wherein the fixing arrangement comprises a main body, in the form of a collar which is axially displaceable relative to the main structure. 39

8. The electricity generating system according to claim 7, wherein the fixing arrangement includes a first pivot for facilitating rotational/pivoting displacement of the float within the second degree of freedom.

9. The electricity generating system according to claim 8, wherein the fixing arrangement includes a second pivot for facilitating rotational/pivoting displacement of the float within the third degree of freedom.

10. The electricity generating system according to claim 8 or 9, wherein the first pivot is provided between the main body of the fixing arrangement and the float, and wherein a first end of the first pivot is fixed to the main body of the fixing arrangement.

1 1. The electricity generating system according to claim 10, wherein the fixing arrangement comprises an intermediate body, wherein a second end of the first pivot is fixed to the intermediate body, and wherein the second pivot is provided between the intermediate body and the float, such that a first end of the second pivot is fixed to the intermediate body, while a second end of the second pivot is fixed to the float.

12. The electricity generating system according to claim 1 1 , wherein the first and second pivots are arranged substantially perpendicularly to each other about the elongate structure.

13. The electricity generating system according to any one of claims 7 to 12, wherein the collar constitutes a linear bearing.

14. The electricity generating system according to claim 13, wherein the collar includes one of a plurality of rollers and slides for supporting the fixing arrangement relative to, and for running on, an outer surface of the elongate structure.

15. The electricity generating system according to claim 14, wherein the rollers are mounted to the collar by way of bearings.

16. The electricity generating system according to any one of the preceding claims, wherein the elongate structure comprises a functional portion and a base portion, and wherein the base portion is anchored to a bed of the body of water. 40

17. The electricity generating system according to claim 16, wherein the functional portion of the elongate structure extends between 2 and 10 meters below a nominal surface level of the body of water, and between 2 and 25 meters above the nominal surface level of the body of water.

18. The electricity generating system according to claim 17, wherein the functional portion of the elongate structure extends at least 4 meters below a nominal surface level of the body of water, and at least 8 meters above the nominal surface level of the body of water.

19. The electricity generating system according to any one of claims 16 to 18, wherein the functional portion of the elongate structure comprises a cross-section which is substantially constant along a length of the functional portion, and wherein the cross-section of the functional portion is one of: i) substantially circular; and ii) a polygon.

20. The electricity generating system according to any one of claims 16 to 19, wherein the elongate structure comprises a tower of a wind turbine.

21 . The electricity generating system according to any one of claims 16 to 20, wherein the base portion of the elongate structure, comprises a lattice structure.

22. The electricity generating system according to claim 2, wherein the float is substantially ringshaped in plan.

23. The electricity generating system according to claim 2, wherein an outer shape of the float viewed in plan is in the form of a regular polygon, which regular polygon has 3 or more sides.

24. The electricity generating system according to any one of the preceding claims, wherein an outer bottom side portion of the float is bevelled or rounded.

25. The electricity generating system according to any one of the preceding claims, wherein top and bottom side portions of the inner cavity of the float are bevelled.

26. The electricity generating system according to any one of the preceding claims, wherein the float has a volume and mass which, in use, displaces a volume of water having a mass equal to between 60% and 90% of a mass of structural parts of the system, excluding the mass of the float. The electricity generating system according to any one of the preceding claims, wherein the elongate structure is configured to be installed in the body of water, at a location where a nominal depth of the body of water is 60 meters or less. The electricity generating system according to any one of claims 1 to 26, further comprising a support structure for supporting the elongate structure relative to a bed of the body of water, and wherein the elongate structure is configured to be installed in the body of water, at a location where a nominal depth of the body of water is between 30 meters and 100 meters. The electricity generating system according to claim 28, wherein the support structure comprises at least a first ring member for receiving the elongate structure in use, and at least a first leg extending between the bed of the body of water and the at least first ring member. The electricity generating system according to claim 29, comprising a second leg extending between the bed of the body of water and the at least first ring member, the first and second legs arranged in a push-pull configuration. The electricity generating system according to any one of the preceding claims, wherein the at least first energy transfer device comprises a first piston arrangement extending between the float and the elongate structure, wherein displacement of the float relative to the elongate structure causes the piston to cause a flow of fluid in a fluid circuit. The electricity generating system according to claim 31 , wherein the fluid circuit includes a fluid line, a hydraulic accumulator and a hydraulic motor/generator unit, the arrangement such that the hydraulic motor/generator unit is provided in fluid flow communication with the fluid line and the hydraulic accumulator. The electricity generating system according to any one of claims 31 or 32, including at least a second piston arrangement, and wherein each of the first and second piston arrangements is fitted between a respective first mount on the elongate structure, and a respective second mount on the float. The electricity generating system according to claim 33, wherein the arrangement of the first and second piston arrangements is one of: i) such that barrel ends of the first and second piston arrangements are fixed to the first mounts and rod ends of the first and second piston arrangements are fixed to the second mounts; and ii) such that rod ends of the first and second piston arrangements are fixed to the first mounts and barrel ends of the first and second piston arrangements are fixed to the second mounts.

35. The electricity generating system according to claim 33 or 34, including a third and a fourth piston arrangement.

36. The electricity generating system according to any one of claims 33 to 35, wherein each piston arrangement is fitted to the first and second mounts respectively, byway of respective multi-axial pivot connection mechanisms.

37. The electricity generating system according to claim 36, wherein each multi-axial pivot connection mechanisms takes the form of a ball joint or universal joint.

38. The electricity generating system according to claim 7, wherein the first linear energy transfer device constitutes a first primary piston arrangement, and wherein the first primary piston arrangement is fitted between a first primary mount on the elongate structure, and a second primary mount on the main body of the fixing arrangement.

39. The electricity generating system according to claim 38, further including a second primary piston arrangement which is fitted between a first primary mount on the elongate structure, and a second primary mount on the main body of the fixing arrangement.

40. The electricity generating system according to claim 38 or 39, wherein each primary piston arrangement is a double acting piston arrangement.

41 . The electricity generating system according to any one of claims 38 to 40, further including a first secondary piston arrangement which is fitted between a first secondary mount on the main body of the fixing arrangement and a second secondary mount on the float.

42. The electricity generating system according to claim 41 , further including a second secondary piston arrangement which is fitted between a first secondary mount on the main body of the fixing arrangement and a second secondary mount on the float. 43

43. The electricity generating system according to claim 32, wherein the float includes an internal compartment for housing the hydraulic motor/generator unit and hydraulic accumulator.

44. The electricity generating system according to any one of claims 32 to 42, further including a compartment supported by the elongate structure at a location above the float, which compartment is provided for housing the hydraulic motor/generator unit and hydraulic accumulator.

45. The electricity generating system according to any one of the preceding claims, further including at least one marine turbine arrangement fixed to a bottom surface of the float.

46. The electricity generating system according to any one of the preceding claims, wherein the float extends at least one of: 1 ) at least 50%; 2) at least 60%; 3) at least 70%; 4) at least 80%; 5) at least 90% and 6) 100%, around the periphery of the elongate structure.

47. The electricity generating system according to claim 1 , wherein the energy transfer device comprises one of i) a rack and pinion arrangement; ii) a linear electro -magnetic arrangement; and iii) a piston arrangement with an integrated accumulator and/or oil tank.

48. The electricity generating system according to claim 47, wherein the piston arrangement with integrated accumulator and/or oil tank further includes at least one integrated valve and/or an integrated motor powering an alternator.

49. An auxiliary power generating system for a wind-turbine located in a body of water, the wind-turbine comprising a pile having a base portion extending below a surface of the body of water, and an upper portion extending above the surface of the body of water, wherein, in use, the upper portion is filled at least partially with air, while the base portion is provided in flow communication with the body of water, such that a level of water within the pile rises and falls in sympathy with a level of the body of water, wherein the auxiliary power generating system comprises a first turbine mounted in fluid flow communication with the air within the upper portion, and, in use, driven by air displaced by the rising and falling water level within the elongate structure.

50. The auxiliary power generating system of claim 49, wherein the first turbine is a multidirectional air turbine and wherein the system includes an opening for airflow between an outside environment and the upper portion. 44

51 . The auxiliary power generating system of claim 49, further comprising a second turbine, the arrangement such that airflow associated with a rising level of water within the pile drives the first turbine, and such that airflow associated with a falling level of water within the pile drives the second turbine.

52. The auxiliary power generating system of any one of claims 49 to 51 , wherein the first turbine is fixed to a base, and wherein a vertical position of the base is displaceable in use, relative to a nominal level of the water within the pile.

53. A current energy converter, comprising: a main structure comprising an elongate structure extending partially above a water surface of a body of water and a base structure; at least a first turbine assembly, in use, arranged within an outer periphery defined by the base structure and provided in fluid flow communication with the body of water.

54. The current energy converter according to claim 53, comprising a plurality of turbine assemblies spaced axially or vertically relative to each other within the outer periphery defined by the base structure.

55. The current energy converter according to claim 53 or claim 54, wherein the base structure comprises a monopile fixed in a bed of the body of water, wherein each turbine assembly is, in use, aligned with a set of opposing openings through wall portions of the pile, and wherein a flow channel is defined through each set of opposing openings.

56. The current energy converter according to claim 55, wherein the pile is reinforced proximate each set of opposing openings.

57. The current energy converter according to claim 56, comprising a reinforcing collar associated with each opening through the wall portion of the pile.

58. The current energy converter according to any one of claims 55 to 57, wherein the pile is reinforced by an axially extending, internal brace.

59. The current energy converter according to claim 58, wherein the axially extending, internal brace comprises a tubular member, having one of a rectangular or circular cross-section. 45

60. The current energy converter according to claim 53 or claim 54, wherein the base structure comprises a lattice or jacket structure defining an axially or vertically extending column within which each turbine is arranged in use.

61 . The current energy converter according to any one of claims 53 to 60, wherein each turbine is mounted to a mounting structure which is axially displaceable relative to the base structure.

62. The current energy converter according to claim 61 , wherein the mounting structure is displaceable between an operative configuration, in which each turbine is arranged in fluid flow communication with the body of water, and an inoperative configuration, in which each turbine is removed from the body of water.

63. The current energy converter according to claim 62, wherein the mounting structure is located at least partially within the elongate structure when displaced into the inoperative configuration.

64. The current energy converter according to any one of claims 61 to 63, further including a hoisting system for axially displacing the mounting structure.

65. The current energy converter according to claim 57, wherein the reinforcing collar is formed by a respective tubular member extending between the opposed openings of each set and across the base member to define a flow channel or tunnel.

66. The current energy converter according to claim 65, wherein each opening comprises a door for closing the flow channel or tunnel.

67. The current energy converter according to claim 66, wherein each tubular member extending between a set of openings comprises an access hatch.

68. A hybrid electricity generating system comprising: an electricity generating system according to claim 1 ; and a current energy converter according to claim 53.

69. A hybrid electricity generating system according to claim 68, further including an auxiliary power generating system according to claim 49. 46

70. A method of lifting a float of an electricity generating system according to claim 1 from a body of water, which float is displaceably fixed relative to an elongate structure, the method comprising the steps of: allowing the float to be displaced relative to the elongate structure to a first lifted position by a first wave; and retaining the float in the first lifted position after the first wave has passed.

71 . The method according to claim 70, comprising the further steps of: allowing the float to be displaced relative to the elongate structure to a second lifted position by a second wave, where the second lifted position is vertically higher than the first lifted position; and retaining the float in the second lifted position after the second wave has passed.

72. The method according to claim 70 or 71 , wherein displacement of the float relative to the elongate structure is associated with a flow of hydraulic fluid in a hydraulic arrangement and wherein the method includes the step of configuring the hydraulic arrangement to allow a flow of hydraulic fluid associated with an upward displacement of the float, thereby allowing the float to be lifted by the wave, and inhibiting a flow of hydraulic fluid associated with a lowering of the float, thereby retaining the float at a lifted position.

73. The method according to claim 72, comprising the further step of providing a positive flow of hydraulic fluid to lift the float from a lifted position to a final lifted position.

74. An electricity generating system, comprising: an elongate pile fixed to a bed of a body of water; a support structure for supporting the pile relative to a bed of the body of water, wherein the support structure comprises: at least a first ring member for receiving the elongate structure in use; a first leg extending between the bed of the body of water and the at least first ring member; and a second leg extending between the bed of the body of water and the at least first ring member, wherein the first and second legs are arranged in a push-pull configuration.

Dated this 17^th day of August 2021 .