NL2026280B1

NL2026280B1 - Hybrid electricity producing arrangement

Info

Publication number: NL2026280B1
Application number: NL2026280A
Authority: NL
Inventors: Robbert Paul Leunissen Thomas
Original assignee: Aquamarine Found
Priority date: 2020-08-17
Filing date: 2020-08-17
Publication date: 2022-04-14
Also published as: WO2022038503A1; EP4196677A1

Abstract

A hybrid electricity producing arrangement or generating system, producing electricity from various renewable sources. The system or arrangement comprises an elongate structure extending above a water surface of a body of water, and a float defining an inner cavity through which the elongate structure extends in use. The arrangement is such that the float extends at least 50% around a periphery of the elongate structure. At least a first energy transfer device extends between the float and the elongate structure. The at least first energy transfer device is actuated by displacement of the float relative to the elongate structure.

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 an electricity producing or generating system, producing electricity from various renewable sources.

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 yet 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/m? and 200 W/m?. That said, current photovoltaic cells and solar generating systems typically have efficiencies below 20%.

Conventional fossil fuel power plants, in contrast, have energy densities tens of times greater than energy densities of renewable energy generating systems, or even more.

Furthermore, the capital and maintenance cost of 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 off-shore 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 energy density of such a wind turbine could be increased, in order to drive the unit-cost of generating electricity 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, hamely wind.

In addition, 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 are a function of the size of the waves.

Consequently, provision needs to be made for the storage of any surplus energy, or for alternative sources of electricity available at times when the demand surpasses the supply. Energy storage in batteries and/or capacitors is relatively expensive, and the life expectancy of batteries is limited.

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 and/or for storing energy so generated.

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; 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.

The float may surround the elongate structure. The system may further comprise a connecting arrangement for displaceably fixing the float relative to the elongate structure, which connecting arrangement may facilitate displacement of the float relative to the structure, in a first degree of freedom.

The first degree of freedom may be a translational degree of freedom. The connecting arrangement may facilitate axial displacement of the float relative to the elongate structure.

The connecting arrangement may comprise a main body, in the form of a collar which is axially displaceable relative to the main structure. The connecting arrangement may facilitate displacement of the float relative to the structure, in a second degree of freedom. The second degree of freedom may be a first rotational degree of freedom. The connecting arrangement may facilitate rotational/pivoting displacement of the float relative to the elongate structure and about a first axis, which extends substantially horizontally. The connecting arrangement may include a first pivot for facilitating rotational/pivoting displacement of the float within the second degree of freedom.

The connecting arrangement may facilitate displacement of the float relative to the structure, in a third degree of freedom, which is a second rotational degree of freedom. The connecting arrangement may facilitate 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. The connecting arrangement may include a second pivot for facilitating rotational/pivoting displacement of the float within the third degree of freedom.

A first pivot may be provided between the main body of the connecting arrangement and the float. A first end of the first pivot may be fixed to the main body of the connecting arrangement. The connecting arrangement may 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 is fixed to the intermediate body, while a second end of the second pivot is fixed to the float.

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

The elongate structure may comprise a functional portion and a base portion. The base portion may be anchored to a bed of the body of water.

The functional portion of the elongate structure may be substantially cylindrical. The functional portion may extend at least 8 meters below a nominal surface level of the body of water, and 16 meters above the nominal surface level of the body of water.

The elongate structure may comprise a tower of a wind turbine. The base portion of the elongate structure, may comprise a lattice structure.

The collar may constitute a linear bearing, and may include a plurality of rollers for supporting the connecting arrangement relative to, and for running on, an outer surface of the elongate structure. The rollers may be mounted to the collar by way of bearings.

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 regular polygon. A bottom side portion of the float may be bevelled, while top and bottom side portions of the inner cavity of the float may be bevelled. The float may have 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 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.

The at least first energy transfer device may typically 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 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 first mount on the elongate structure, and a 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 5 and second mounts respectively, by way of respective multi-axial pivot connection mechanisms. Each multi-axial pivot connection mechanisms may take the form of a ball 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 connecting arrangement. The system may include a second primary piston arrangement which is may be fitted between a first primary mount on the elongate structure, and a second primary mount on the main body of the connecting arrangement. Each primary piston arrangement may be a double acting cylinder. The system may include a first secondary piston arrangement which is fitted between a first secondary mount on the main body of the connecting arrangement and a second secondary mount on the float.

The system may further include a second secondary piston arrangement which is fitted between a first secondary mount on the main body of the connecting 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.

The system may include at least one marine turbine arrangement fixed to a bottom surface of the float.

The system may also include a power take-up system arranged within the elongate structure. The power take-up system may include at least a first take-up body which may be displaceable between a bottom location and a top location, and a first displacing arrangement for displacing the first take-up body between the bottom and top locations. The first displacing arrangement may comprise a motor/generator unit and a cable and pulley arrangement. An end of the cable may be fixed to the first take-up body. The motor/generator unit may be configurable as a motor to hoist the first take-up body to the top location, and as a generator when lowering the first take-up body to the bottom location. The motor/generator unit may be one of: i) a hydraulic motor/pump unit; and ii) an electrical motor/alternator unit. The first take-up body has a mass not exceeding one third of a total mass of structural parts of the system.

Alternatively, a second take-up body and a second displacing arrangement may be provided. Now, the first and second take-up bodies may have a combined mass not exceeding one third of a total mass of structural parts of the system.

The system may furthermore comprise a turbine assembly comprising at least a first turbine unit and a mounting structure to which the at least one turbine unit is mounted. The mounting structure may be displaceable relative to the base portion. The first turbine unit may be rotated about the longitudinal axis of the base portion, to align the turbine with a prevailing underwater current, in use.

A bottom end of the functional portion may be open ended. The mounting structure can be hoisted at least partially through the open end of the functional portion, and into the functional portion.

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 alternative embodiments, the energy transfer devices may comprise either a rack and pinion arrangement or a linear electro-magnetic arrangement.

In accordance with a second aspect of the invention, there is provided a hybrid electricity producing arrangement comprising: an offshore wind turbine, comprising a tower anchored to an underwater bed, the tower supporting a nacelle; and a first float, attached to the tower by an attachment arrangement; and a first energy transfer device, extending between the float and the tower, which is actuated by displacement of the float relative to the tower.

There is provided for the attachment arrangement to comprise an arm, pivotably attached to the tower. The energy transfer device may comprise a hydraulic piston arrangement, a rack and pinion arrangement or a linear electro-magnetic arrangement.

There is provided for the hybrid electricity producing arrangement further to comprise a second float, attached to the tower by an attachment arrangement, and a second energy transfer device, extending between the float and the tower, which is actuated by displacement of the float relative to the tower. Further floats and energy transfer devices may also be provided.

In accordance with a third aspect of the invention, there is provided an electricity producing arrangement comprising: a support structure, anchored to an underwater bed, having a first portion extending below a water surface level and a second, hollow portion, extending above a water surface level; at least a first marine turbine mounted to a mounting structure, which is retained by the support structure; a hoist system for adjusting a vertical position of the mounting structure relative to the support structure, wherein, when the mounting structure is hoisted to a vertical position where it is retained by the first portion, the marine turbine is provided in fluid flow communication with an underwater current, and wherein, when the mounting structure is hoisted to a vertical position where it is retained by the second portion, the marine turbine is situated above the water surface level.

The electricity producing arrangement may further comprise a compartment supported by the second portion of the support structure and provided in communication with an inside of the second portion, so as to provide access to the marine turbine when same is hoisted into the second portion. The compartment may be a machine room/maintenance room. The first portion may comprise a lattice structure.

A vertical position of the mounting structure, when retained by the first portion of the support structure, may be selected based on a strength of an underwater current.

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 first configuration, and wherein an elongate structure of said wave generating system forms part of a conventional off-shore wind turbine; Figure 2 shows a perspective view of an alternative embodiment of the system of Figure 1; Figure 3 shows a perspective view of an alternative embodiment of the system of Figure 1, in which piston arrangements are configured in a second configuration;

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 an assembly comprising the float, the fixing arrangement and secondary piston arrangements of the system of Figure 1, the float shown in section better to illustrate interaction between the various components;

Figure 6 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 7 shows a partial side view the alternative embodiment of Figure 1 as illustrated in Figure 3, 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 the second degree of freedom;

Figure 8 shows a top view of the system of Figure 1, in which the float is substantially ring-shaped;

Figure 9 shows a top view of the system of Figure 1, in which the float is substantially octagonal;

Figure 10 shows a side view of the system of Figure 1;

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

Figure 12 shows a further alternative embodiment of the system of Figure 1;

Figure 13 shows a sectioned side view of the float of the system of Figure 1, in which details of an internal compartment is shown;

Figure 14 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 15 shows a side view of an alternative embodiment of the system of

Figure 1, including a power take-up or energy storage system;

Figure 16 shows a top view of the power take-up system of Figure 16;

Figure 17 shows a side view of the system of Figure 1, including further current turbines mounted to the float.

Figure 18 shows a sectioned side view of the float of the system of Figure 1, in which details of alternative forms of energy transfer devices are shown; and Figure 19 shows the sectioned side view of the float of Figure 18, having pivoted along the first axis.

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 therebetween and indirect connections between members in which one or more other members are interposed therebetween. 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 electricity from waves (hereinafter a “wave generating system” 12), a sub-system provided for generating electricity from currents (hereinafter a “current generating system” 14), a power storage or take-up system 16 and the like. 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. 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 (which is best indicated in figure 11) of the elongate structure 18, has a substantially constant cross-section, and is typically cylindrical. 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 10, the elongate structure 18 forms part of a conventional wind turbine 28. Certain advantages of using 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 part of the tower 34. 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 off-shore wind turbines 28, and do not include land based wind turbines. That said, in cases where the power-storage or take-up system 18 is used in isolation, same may find application in both off-shore and land based wind turbines 28 of the conventional type.

Typically, the wind turbines 28 are located 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. In areas where the depth of the body of water 22, exceeds 60 m, the size of support structures or of the conventional tower becomes impractical. 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 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, 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 surrounds the elongate structure 18 completely. The float 42 is therefore substantially ring- shaped when viewed from above, and as best shown in figure 8. That said, and as shown best in figure 9, the float 42 may furthermore take on the shape of a regular polygon {such as the octagon shown in figure 9). 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. 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.

The float 42 is fixed relative to the elongate structure 18 by means of a 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 be extended or compressed, in turn, causing a flow of hydraulic fluid in a 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.

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 13, fluid lines or ports designated by reference numeral 50.1 designate fluid lines or ports from 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 9. The fixing arrangement 46 comprises a main body 58 in the form of a collar around the elongate structure 18. 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) which are urged against the elongate structure 18 and which are fixed to the collar through bearings. The rollers are provided for decreasing 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 liming 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.

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 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, and reduces losses due to improper alignment of the float relative to the direction of travel of the wave. Therefore, even though a single degree of freedom movement of the float 42 is potentially viable, and therefore incorporated herein in its entirety, the applicant believes that a multi-degree of freedom movement of the float 42 is preferable, and should be more effective. Furthermore, the additional degrees of freedom 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 the second degree of freedom, the float 42 pivots about a first axis 68, which extends substantially horizontally. When the float 42 is displaced within 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 free 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 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.

The piston arrangements used with the wave generating system 12, may be arranged in various configurations. A first configuration is typically shown in figures 1, 2 and 4 to 6, while the second configuration is typically shown in figures 3 and 7.

In the first configuration, at least a first, but typically up to four or more primary piston arrangements (generally indicated by reference numeral 78, 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, in the form of ball 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.

In the first configuration, at least a first, but typically two (as shown in figure 1) 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.

The secondary piston arrangements 82 are also double acting piston arrangements.

In the second configuration of the piston arrangements (as best shown in figure 3), 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, inthe 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 3) 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 13, 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 13, 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.

In an alternative embodiment, as shown typically in figures 14 to 16, 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 10 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 11, 12 and 14 to 17), 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 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 6, 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 without interfering with the fixing arrangement 46.

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 weighs 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 the net force transferred to the elongate structure 18 is a function of the volume of water displaced by the float 42, and 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 down-stroke 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, specifically with reference to figures 14 and 15. 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 comprises a lattice structure. 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 is provided at a bottom of the base portion 40, around which a cable 110 is wound, which cable 110 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, 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 114 within which the mounting structure 106 may be hoisted. The compartment 94 may be open to the elevator shaft 114, to allow for easy maintenance of the marine turbine assemblies 104.

Guide members 115 are provided in the elevator shaft 114 and also the base portion 40, for guiding the mounting structure 108. 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 115.

A bottom end 116 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 118.

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.

As shown in figure 17, 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 theinternal 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 constant depth relative to the nominal water level 26.

The power take-up system 16 is typically shown in figures 16 and 17. It will be appreciated that, in the embodiments shown herein, the power take-up system and current generating system 14 cannot both be used at the same time. However, it is foreseen that some modifications may result in the simultaneous use of the power take-up system 16 and the current generating system 14.

The power take-up system 16 is arranged within the elongate structure 18 and includes at least a first, but typically a first and a second take-up body (118, 120). The first and second take-up bodies (118, 120) are independently displaceable, between a bottom location and a top location. A first and second displacing arrangement (122, 124) are provided for displacing the first respective take-up bodies (118, 120) to the top positions.

The displacing arrangements (122, 124) typically take the form of motor-gear units, coupled with alternators.

In the embodiment shown, the take-up system 16 also includes a plurality of take-up pulleys 126 and take-up cables 128 to facilitate the displacement of the take-up bodies (118, 120). It will be understood that alternative arrangements are possible, such as replacing the take-up pulleys 126 and take-up cables 128 with rack-and-pinion arrangements, linear electro-magnetic systems, and the like.

The power take-up system 16 is provided with anti-roll back or fall arrest systems of the known kind, and typically employed in elevator systems of the known kind.

In this way, the take-up bodies (118, 120) are arrested and prevented from free-falling, should the take-up cable 128 fail.

The take-up bodies (118, 120) have substantial masses. Typically, the combined mass of the take-up bodies (118, 120) is in order of a quarter or up to a third of the total mass of the wind turbine structure.

In times when the net amount of electricity generated by the overall system 10, including the wind turbine 28, surplus electricity may be used to hoist the take-up bodies towards to top positions. The take-up bodies may be locked in place in these positions, effectively storing potential energy be virtue of their elevated positions.

If the net amount of electricity generated by the system 10 becomes low, the take-up bodies (118, 120) can be lowered towards the lower positions, and the displacing arrangements (122, 124) can be configured to generate electricity from the displacement of the take-up bodies.

The displacing arrangements (122, 124) may take the form of electric or hydraulic motors with alternators or pump arrangements which are driven by the take-up bodies (118, 120) when same are displaced under the influence of gravity to the lower positions.

In cases where the base portion 40 is solid, the lower positions of the take- up bodies may be below the water surface 20, or may even be below the surface of the bed

36. The take-up bodies (118, 120) are substantially semi-circular to enable them to move past one another.

It will be appreciated that the take-up system may be used to increase the amount of electricity generated by the system 10 for a relatively short period of time, and may be used to smooth the supply of electricity by the system 10.

It will be understood that the take-up pulleys 126 and cables 128 can be replaced by take-up sprockets and chains (not shown) or by a rack and pinion system (not shown). It will be appreciated that the addition of substantial weight to the top of the tower may render same unstable in cases where high wind speeds are experienced.

A permissible height or vertical position of the first and second take-up bodies (118, 120) may be determined based on prevailing weather conditions.

It is also possible to lift the two take- up bodies (118, 120) independently from each other to retain same at positions where the stability of the tower will not be negatively impacted.

Also, the two take-up bodies (118, 120) need not be of the same size or mass, and again, the permissible vertical position of each take-up body may be determined based the specific mass of each take-up body.

A PLC may determine and provide input to control the vertical positions of the first and second take-up bodies (118, 120) and may receive input from weather forecasts.

Generally, it will be appreciated that both take-up bodies are ideally at all times located as high as possible, since the potential energy stored in these bodies is a function of the vertical position of the bodies and the weight thereof.

Furthermore, it will be appreciated that the power take-up or storage system 16 is not limited to storing energy generated by the specific wind turbine 28 in which it is installed.

The take-up bodies may, for example, be hoisted to the upper positions utilising electricity obtained from neighbouring wind turbines, a power grid, or alternative sources of electricity.

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 easily 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. 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 sub-sea bed, and the installation of sub-sea cables, can be diluted by the addition of electricity generating, harvesting and storing 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, harvesting and storing arrangements and systems, as described herein.

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 and the power storage or take-up system 16 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 provide 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, in such cases, the take-up system may be utilized to supplement electricity generated by the wave generating system 12 and the current generating system 14 (provided potential energy was available in the take-up system).

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 ar an electrical alternator/motor unit), linear electromagnetic arrangements (such as used in Maglev trains or rollercoasters launch systems).

Furthermore, in an alternative embodiment, which is shown in figures 18 and 19, 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 18 and 19, 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).

It will be appreciated that all 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 138 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. In this regard, provision is made for a hybrid electricity producing arrangement {which is not shown in the figures) which comprises at least one, but typically two or more floats, independently and individually attached to the tower of a conventional offshore wind turbine. Here, each float is associated with a separate attachment means, typically in the form of an arm pivotably fixed to the tower.

In this embodiment, each float is associated with a separate energy transfer device, such as those described above in the embodiment illustrated in the figures, and which is actuated by displacement of the float relative to the tower.

Even though this embodiment has more moving parts and will therefore be more maintenance intensive, it is believed that this embodiment still provides a useful means of utilising existing hardware, in the form of the tower of a wind turbine, to generate more electricity from further renewable sources.

It will be understood that ancillary aspects of the illustrated embodiment, such as the current generating system 14 and the power storage or take-up system, can be added to this present embodiment, and therefore forms part of the present disclosure.

Claims

CONCLUSIONS

An electricity generating system comprising: an elongate structure extending above a water surface of a water body; a float defining an internal cavity through which the elongate structure extends in use, the arrangement being such that the float extends at least 50% around a perimeter of the elongate structure; and at least one 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.

The electricity generating system of claim 1, wherein the float surrounds the elongate structure.

An electricity generating system according to claim 1 or 2, further comprising a connecting arrangement for movably fixing the float with respect to the elongate structure.

The electricity generating system of claim 3, wherein the connecting arrangement facilitates displacement of the float relative to the structure in a first degree of freedom.

The electricity generating system of claim 4, wherein the first degree of freedom is a translational type of freedom, and wherein the connecting arrangement facilitates axial displacement of the float relative to the elongate structure.

An electricity generating system according to any one of claims 3 to 5, wherein the connecting arrangement comprises a main body, in the form of a collar, which is axially displaceable with respect to the main structure.

An electricity generating system according to any one of claims 3 to 6, wherein the connecting arrangement facilitates displacement of the float relative to the structure in a second degree of freedom.

The electricity generating system of claim 7, wherein the second degree of freedom is a first degree of freedom of rotation type, and wherein the connecting arrangement has rotational/pivoting displacement of the float relative to the elongate structure and about a first axis extending substantially horizontally. extends, facilitates.

The electricity generating system of claim 8, wherein the connecting arrangement comprises a first pivot for facilitating rotational/pivoting movement of the float within the second degree of freedom.

An electricity generating system according to claim 8 or 9, wherein the connecting arrangement facilitates displacement of the float relative to the structure in a third degree of freedom.

The electricity generating system of claim 10, wherein the third degree of freedom is a second degree of freedom of rotation type, and wherein the connecting arrangement has rotational/pivoting displacement of the float relative to the elongate structure and about a second axis extending substantially horizontally. and extending substantially perpendicular to the first axis.

The electricity generating system of claim 11, wherein the connecting arrangement comprises a second pivot member for facilitating rotary/pivoting movement of the float within the third degree of freedom.

The electricity generating system of claim 6, wherein a first pivot member is provided between the main body of the connecting arrangement and the float, and wherein a first end of the first pivot member is fixed to the main body of the connecting arrangement.

An electricity generating system according to claim 13, wherein the connecting arrangement comprises an intermediate body, wherein a second end of the first pivot member is fixed to the intermediate body, and wherein a second pivot member is provided between the intermediate body and the float such that a first end of the second pivot member is fixed with respect to the intermediate body, while a second end of the second pivot member is fixed to the float.

The electricity generating system of claim 14, wherein the first and second pivot members are arranged substantially perpendicular to each other about the elongate structure.

An 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.

The electricity generating system of claim 16, wherein the functional portion of the elongate structure is substantially cylindrical, and wherein the functional portion is located at least 8 meters below a nominal surface level of the body of water, and at least 16 meters above the nominal surface level of the water body.

An electricity generating system according to claim 16 or 17, wherein the elongate structure comprises a wind turbine tower.

An electricity generating system according to any one of claims 16 to 18, wherein the base portion of the elongate structure comprises a skeleton.

The electricity generating system of claim 6, wherein the collar forms a linear bearing.

The electricity generating system of claim 20, wherein the collar comprises a plurality of rollers for carrying the connecting arrangement relative to, and for walking on, an outer surface of the elongate structure.

The electricity generating system of claim 21, wherein the rollers are mounted to the collar by means of bearings.

The electricity generating system of claim 2, wherein the float is substantially annular in plan view.

The electricity generating system of claim 2, wherein an external shape of the float, viewed in plan, is in the shape of a regular polygon.

An electricity generating system according to any one of the preceding claims, wherein a side portion at the bottom of the float is chamfered.

An electricity generating system according to any one of the preceding claims, wherein side portions at the top and at the bottom of the inner cavity of the float are chamfered.

An electricity generating system according to any preceding claim, wherein the float has a volume and a mass which, in use, is a volume of water with a mass equal to between 60% and 90% of a mass of structural members of the system, excluding the mass of the float.

An electricity generating system according to any one of the preceding claims, wherein the elongate structure is configured to be installed in the water body at a location where a nominal depth of the water body is 60 meters or less.

An 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 that the piston produces a flow of fluid in a fluid circuit.

The electricity generating system of claim 29, wherein the fluid circuit comprises a fluid conduit, a hydraulic accumulator and a hydraulic motor/generator unit, the arrangement being such that the hydraulic motor/generator unit is provided in fluid flowing communication with the fluid conduit and the hydraulic accumulator.

An electricity generating system according to any one of claims 29 or 30, comprising at least a second piston arrangement, and wherein each of the first and second piston arrangements is mounted between a first mounting on the elongate structure and a second mounting on the float.

The electricity generating system of claim 31, wherein the arrangement of the first and second piston arrangements is one or more of the following arrangements: i) such that cylinder ends of the first and second piston arrangements are fixed to the first assemblies and rod ends of the said first and second piston arrangements. 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 assemblies and cylinder ends of the first and second piston arrangements are fixed to the second assemblies.

An electricity generating system according to claim 31 or 32, comprising a third and a fourth piston arrangement.

An electricity generating system according to any one of claims 31 to 33, wherein each piston arrangement is mounted on the first and second mountings, respectively, by way of respective multi-axial pivot connection mechanisms.

The power generating system of claim 34, wherein each multi-axial pivot linkage mechanism is in the form of a ball joint.

The power generating system of claim 6, wherein the first linear energy transfer device forms a first primary piston arrangement, and wherein the first primary piston arrangement is disposed between a first primary mounting on the elongate structure and a second primary mounting on the connecting main body. line-up.

The power generating system of claim 36, further comprising a second primary piston arrangement disposed between a first primary mounting on the elongate structure and a second primary mounting on the main body of the connecting arrangement.

An electricity generating system according to claim 36 or 37, wherein each primary piston arrangement is a double acting cylinder.

An electricity generating system according to any one of claims 36 to 38, further comprising a first secondary piston arrangement disposed between a first secondary mounting on the main body of the connecting arrangement and a second secondary mounting on the float.

The electricity generating system of claim 39, further comprising a second secondary piston arrangement disposed between a first secondary mounting on the main body and the connecting arrangement and a second secondary mounting on the float.

The electricity generating system of claim 30, wherein the float comprises an interior compartment for housing the hydraulic motor/generator unit and the hydraulic accumulator.

An electricity generating system according to any one of claims 30 to 40, further comprising a compartment carried by the elongate structure at a location above the float, the compartment being provided for receiving the hydraulic motor/generator unit and the hydraulic accumulator.

An electricity generating system according to any preceding claim, further comprising at least one marine type turbine arrangement attached to a lower surface of the float.

An electricity generating system according to any one of the preceding claims, further comprising a force receiving system disposed within the elongate structure.

An electricity generating system according to claim 44, wherein the energy receiving system comprises at least a first receiving body movable between a lower location and a higher location, and comprising a first displacement arrangement for moving the first receiving body between the lower and the upper Location.

An electricity generating system according to claim 45, wherein the first displacement arrangement comprises a motor/generator unit and a cable and pulley arrangement, one end of the cable being fixed to the first receiving body, and wherein the motor/generator unit is configurable as a motor so as to hoisting the first receiving body to the higher location, and as a generator when the first receiving body is lowered to the lower location.

An electricity generating system according to claim 46, wherein the motor/generator unit is a unit of: i) a hydraulic motor/pump unit; andi) an electric motor/generator unit.

An electricity generating system according to any one of claims 45 to 47, wherein the first receiving body has a mass that does not exceed one third of a total mass of structural parts of the system.

An electricity generating system according to any one of claims 45 to 48, comprising a second receiving body and a second displacement arrangement, and wherein the first and second receiving bodies have a combined mass which is not one third of a total mass of structural parts of the said transcends system.

The electricity generating system of claim 19, further comprising a turbine assembly comprising at least a first turbine unit and a mounting structure to which the at least one turbine unit is mounted, the mounting structure being movable relative to the base portion.

The electricity generating system of claim 50, wherein the first turbine unit is rotatable about the longitudinal axis of the base portion, in use to align the turbine with a prevailing underwater current.

An electricity generating system according to any one of claims 50 or 51, wherein a lower end of the functional portion has an open end, and wherein the mounting structure is extendable at least in part through the open end of the functional portion, and into the functional portion. be towed.

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

The electricity generating system of claim 1, wherein the energy transfer device comprises one of i) a rack and pinion arrangement; and ij a linear electromagnetic arrangement.

55. A hybrid electricity generating arrangement comprising: an offshore wind turbine comprising a tower anchored to an underwater bed, the tower supporting a nacelle; and a first float attached to the tower by means of a mounting arrangement; and a first energy transfer device extending between the float and the tower, which is actuated by displacement of the float relative to the tower.

The hybrid electricity generating arrangement of claim 55, wherein the connecting arrangement comprises an arm pivotally attached to the tower.

The hybrid electricity generating arrangement of claim 55, wherein the energy transfer device comprises one of the following: i} a hydraulic piston arrangement; ii) a rack and pinion arrangement; and iii) a linear electromagnetic arrangement.

The hybrid power generating arrangement of claim 55, further comprising: a second float secured to the tower by means of a mounting arrangement; and a second energy transfer device extending between the float and the tower, which is actuated by displacement of the float relative to the tower.

59. A hybrid electricity generating arrangement comprising: a support structure anchored to an underwater bed having a first portion extending below a water surface level and a second hollow portion extending above a water surface level;

at least one marine-type first turbine mounted on a mounting structure held by the support structure; a hoisting system for adjusting the vertical position of the mounting structure with respect to the support structure, wherein when the mounting structure is hoisted to a vertical position in which it is held by the first portion, the marine type turbine is provided in fluid communication with an underwater flow, and wherein, when the mounting structure is hoisted to a vertical position where it is held by the second portion, the marine type turbine is above the water surface level.

The power generating arrangement of claim 59, further comprising a compartment carried by the second portion of the support structure and provided for communication with an interior of the second portion to provide access to the marine-type turbine when located in the second portion. has been towed.

An electricity generating arrangement according to claim 59 or 60, wherein the first portion comprises a skeleton.

An electricity generating arrangement according to any one of claims 59 to 61, wherein a vertical portion of the mounting structure, when held by the first portion of the support structure, is selected based on a strength of the underwater current.