GB2574390A

GB2574390A - Renewable energy conversion apparatus

Info

Publication number: GB2574390A
Application number: GB1808933.4A
Authority: GB
Inventors: Foster Graham
Original assignee: Marine Power Systems Ltd
Current assignee: Marine Power Systems Ltd
Priority date: 2018-05-31
Filing date: 2018-05-31
Publication date: 2019-12-11
Also published as: GB201808933D0

Abstract

A buoyant energy converting apparatus comprises: a wind energy converter, eg a wind turbine 12 or kite system, supported by a rigid framework connection member 16 on a buoyant platform 14. The buoyant platform 14 may comprise a planar rectangular lattice framework 24 having a float 26 at each corner. The connection member 16 may comprise a lattice framework forming a rectangular frustrum. Wave energy converters 42, eg each comprising an energy capturing float 38, are provided eg on the upper surface of the buoyant platform 14. In the in-use configuration (fig.3) the buoyant platform 14 is submerged in the body of water with the connection member 16 protruding from the surface of the body of water such that the wind energy converter 12 is not in contact with the body of water and with the floats 38 near the water surface. In a storm configuration (fig.4), the floats are held adjacent the platform 14. The apparatus aims to provide increased stability in stormy conditions, a more consistent supply of power and improved levelised cost.

Description

Renewable energy conversion apparatus

Field of the Invention

The present invention relates to renewable energy systems, in particular to wave energy systems and floating wind systems.

Background to the Invention

Wave Energy and floating offshore wind energy have both been identified as leading technology options to decarbonise the global energy system. Many sites for these technologies overlap, for example the Atlantic coast of Europe has both an excellent wind resource and an excellent wave resource. Furthermore, both technologies share common challenges such as how to deliver energy to the shore, how to transport and maintain machines at sea, and how to survive storms.

It makes sense therefore to consider methods to combine the two technologies in a single device which could have numerous advantages, for example: the two sources of generation could share a common structure and energy transmission system, reducing capital costs; transportation, installation and maintenance can also be shared further reducing costs; two independent sources of energy allow the machine to continue generating energy in time of high wind but low waves and vice versa; and the energy per area of seabed can be maximised.

Combining wave and floating wind energy would pose several challenges which would need to be solved to enable this technology to be successful. The device would need to provide a stable reference for both the wind and the wave energy converters, but in particular, if a traditional wind turbine were to be used, stability of the turbine is paramount. The device would also need to be easily assembled, transported and maintained with the minimal use of highly specialised and expensive equipment-for example heavy lift crane barges. The device would also need to be able to survive storms, preferably with a strategy that prevents it being exposed to storm loads in the first place as opposed to simply over engineering for survival at high cost.

It is therefore desirable to provide an apparatus for harvesting wind energy, wherein overall level and consistency of device output is preferably improved, levelised cost of energy is preferably reduced, and power per area of seabed is preferably increased, and further wherein there is preferably increased stability and reduced likelihood for malfunctioning in stormy conditions. It is also desirable to overcome the problems presented by current attempts to combine wind energy and wave energy harnessing systems.

Summary of the Invention

In accordance with a first aspect of the present invention, there is provided a buoyant energy converting apparatus for converting energy obtained from renewable energy sources to useful energy, the apparatus comprising:

a wind energy converter;

a buoyant platform arranged to support the wind energy converter in a body of water having a surface and a bed; and a connection member comprising a rigid framework, the connection member being positioned between the wind energy converter and the buoyant platform and arranged to provide a gap between the wind energy converter and the buoyant platform, wherein the buoyant platform comprises an in-use configuration in which the buoyant platform is submerged in the body of water, and wherein in the in-use configuration the connection member protrudes through the surface of the body of water such that the wind energy converter is located substantially above the body of water; wherein the apparatus further comprises a wave energy converter in communication with the buoyant platform, the wave energy converter being arranged to convert wave energy from the body of water to the useful energy.

Instability in stormy conditions is preferably reduced in the solution provided by the present invention, when compared with currently available technology. Increased stability is preferably afforded by a gap between the buoyant platform and the wind energy converter, as is provided by the connection member having a rigid open framework structure. Said gap will preferably be understood to be contrary to forms of technology having a wind energy converter, such as a wind turbine, in direct communication with a buoyant platform. In such currently available forms of technology, as discussed above, the level of resistance to movement of a medium (such as water or air) experienced by currently available technology leads to movement, increased tension and also instability in the technology, particularly in turbulent conditions.

The term “rigid framework” will be understood by the skilled addressee to mean a structural component arranged for support and being penetrable by a medium, such that resistance to movement of said medium is minimised (i.e. an open framework is preferably provided). The rigid framework of the connection member is arranged to provide the gap between the wind energy converter and the buoyant platform. Preferably said gap causes minimum resistance to movement of air or water when the apparatus of the first aspect of the present invention is in use, and as such provides for maximum stability of the apparatus in stormy conditions, in which the extent of movement of said mediums, and their movement speed, and thus the level of resistance produced, would be expected to be greater. Maximum stability is preferably provided by reduced movement of the buoyant platform and the wind energy converter. In embodiments wherein the buoyant platform is tethered to, or otherwise in communication with, the bed of the body of water, maximum stability is also preferably provided by reduced tension in a tethering member, which may preferably be a depth-setting member.

The “open framework” may preferably take on a number of possible forms, provided that in such forms, resistance to movement of a medium, such as water or air, is minimised. Examples of such a framework may include, for instance, a lattice frame, a reticulated frame, a perforated frame, a foraminous frame, a porous frame, a penetrable frame, and/or a skeletal frame.

In the context of the present invention, in the in-use configuration the connection member protrudes through the surface of the body of water, and as such, the medium passing through the connection member is preferably water (beneath the surface of the body of water) and air (above the surface of the body of water). In embodiments comprising a transport and maintenance configuration, the buoyant platform is preferably substantially floating upon the surface of the body of water in such a configuration, and as such, in said configuration, the medium is preferably air. Minimising resistance to movement of the medium preferably provides stability to the apparatus in normal use and in, for example, stormy conditions, turbulent sea conditions, large waves, and/or high winds.

“Renewable energy sources” will be understood to mean any renewable energy source conceivable, and available either presently or in the future. Preferably the renewable energy sources are wind power and wave power. The term “useful energy” will be understood by the skilled addressee to mean an energy arranged to be stored and otherwise used. Preferably the useful energy comprises electrical energy. The term “positive buoyancy” is used to refer to a buoyance that is neither neutral or negative.

The term “arranged to support the wind energy converter in a body of water” will be understood by the skilled addressee to mean arranged to support the mass of a wind energy converter, such that it is optimally oriented when in use, when the buoyant platform is located within a body of water. This term is not used to imply location of the wind energy converter within the body of water, and notably in the present invention the wind energy converter is preferably supported substantially above the body of water in the in-use configuration.

Preferably the gap defines a storm clearance distance, the storm clearance distance being a distance that is long enough for the wind energy converter to remain above the surface of the body of water in the in-use configuration, and/or a storm configuration in embodiments comprising such a configuration.

Preferably the body of water is a sea or an ocean.

The term “in-use configuration” is used herein to mean a necessary configuration of the invention when carrying out its primary use, that is to convert energy from renewable energy sources to the useful energy.

The term “submerged” will be understood to mean located completely below the surface of the body of water. The term “substantially above the body of water” will be understood by the skilled reader to mean that the wind energy converter is not in contact with the body of water in the in-use configuration.

Preferably the wave energy converter comprises an energy capturing member coupled to the energy converting member. The energy capturing member is preferably arranged to capture and transfer energy from the renewable energy source to the energy converting member, wherein the energy is converted to the useful energy. In some embodiments, the energy capturing member may be coupled to one or more energy converting members. In preferable embodiments, the renewable energy source comprises waves.

Preferably in the in-use configuration, the energy capturing member is positioned at or proximate the surface of the body of water. The preferable location of the energy capturing member on or proximate the surface of the body of water preferably enables the capturing of wave energy in the form of a changing in the distance between the energy capturing member and the energy converting member. In preferable embodiments, the energy converting member is located on, or proximate, the buoyant platform, which preferably remains stationary in the in-use configuration. In such embodiments, preferably the location of the energy capturing member on or proximate the surface of the body of water preferably enables the capturing of wave energy in the form of a changing in the distance between the energy capturing member and the buoyant platform.

Preferably the apparatus further comprises a storm configuration, wherein in the storm configuration, the energy capturing member is positioned at, within, or proximate the buoyant platform.

Preferably, in embodiments comprising a wave energy converter having an energy capturing member, the energy capturing member is located at a distance from an uppermost surface of the connection member while the apparatus is in the in-use configuration. In such embodiments, which preferably comprise a storm configuration, in the storm configuration, said distance is increased.

In stormy conditions, comprising large waves and/or high winds, additional resistance between the water and the buoyant platform and the energy capturing member would be expected. In contrast to the preferable in-use configuration - wherein the energy capturing member is located proximate or on the surface of the body of water - in the storm configuration, the energy capturing member is preferably located proximate or on the buoyant platform, which preferably minimises said resistance. In minimising said resistance, the preferable storm configuration minimises forces on the apparatus and consequently movement of the apparatus and/or tension on any depth-setting member. As such, stability is maximised and preferably the wind energy converter can remain operational. In currently available technology, wind energy converters, such as wind turbines, may suffer reduction in, or loss of, function upon excessive movement or swaying, which may be in stormy conditions. Such conditions may be exacerbated in a floating wind apparatus, wherein a combination of high winds and stormy seas can have a compounding effect on movement of the apparatus. Preferably, the apparatus of the present invention remains substantially stable in such conditions and therefore preferably maximises energy conversion and/or power output by limiting reduction in, or loss of, function.

Preferably the energy capturing member is coupled to the energy converting member by an adaptable coupling member arranged to define a distance between the energy capturing member and the energy converting member. In preferable embodiments, the energy converting member is located on, or proximate, the buoyant platform. In such embodiments, the adaptable coupling member is arranged to define a distance between the energy capturing member and the buoyant platform. Preferably said adaptable coupling is performed by a winch. In alternate embodiments, the adaptable coupling may be a function of the energy converting member.

Preferably the wave energy converter is arranged to convert relative movement between said energy converting member and said energy capturing member to the useful energy. As discussed, the energy converting member is preferably located proximate or on the buoyant platform and as such, relative movement between the energy capturing member and the buoyant platform is also preferably converted to the useful energy. The distance between the energy capturing member and the energy converting member is preferably defined by an adaptable coupling member. An example of a suitable wave energy converter would be the Marine Power Systems WaveSub (RTM).

In preferable embodiments, the adaptable coupling member is a flexible line which is preferably substantially non-elastic. Preferably the energy converting member comprises a drum around which the coupling member is arranged to be wound, wherein the adjustment of distance between the energy capturing member and the energy converting member causes the coupling member to drive a generator. The length of the adaptable coupling member is preferably arranged to be adapted and/or adjusted to provide an optimal functioning of the apparatus. Preferably the energy converting member comprises a winch, the winch being arranged to adjust the length of the coupling member, and thus the distance between the energy capturing member and the energy converting member. In embodiments comprising a storm configuration, the winch is preferably used to reduce the distance between the energy capturing member and the energy converting member such that the energy capturing member is on or proximate the buoyant platform. Preferably the apparatus comprises a control system having a sensor arranged to detect one or more parameters characteristic of a storm. Preferably the control system is further arranged to configure the apparatus into the storm configuration when parameters characteristic of a storm are detected, wherein said configuration by the control systems preferably includes actuation of said winch.

Preferably the energy capturing member comprises a float.

Preferably the buoyant platform comprises an adaptable depth-setting member arranged to define, over a predetermined range:

a depth between an uppermost surface of the buoyant platform and the surface of the body of water, and a buoyancy distance of a lowermost surface of the buoyant platform from the bed of the body of water.

The adaptable depth-setting member preferably comprises at least one mooring line arranged to tether the buoyant platform to the bed of the body of water, and a winch arranged to adjust the length of the respective mooring line in order to define the depth and the buoyancy distance.

Preferably, in embodiments comprising a storm configuration, the storm configuration comprises a storm clearance depth, wherein the storm clearance depth is preferably equal to, or greater than, 20 m. Preferably the adaptable depth-setting member is arranged to adjust the depth to the storm clearance depth in storm conditions. Preferably, in embodiments comprising a control system arranged to detect parameters characteristic of a storm, the control system is arranged to actuate the adaptable depth-setting member to achieve the storm clearance depth when parameters characteristic of a storm are detected.

Preferably the buoyancy of the buoyant platform is arranged to provide an adequate tension in the depth-setting member, wherein the adequate tension provides a stability to the buoyant platform when in the in-use configuration. Preferably the buoyant platform comprises a positive buoyancy.

Preferably the stability and the tension in the depth-setting member is arranged to substantially inhibit movement of the buoyant platform.

In the context of the present invention, stability is to be taken to mean the lack of unnecessary movement of the apparatus and/or the lack unnecessary tension upon said apparatus. Said unnecessary movement may typically be caused by movement of the water within the body of water, or movement of air above the body of water. Preferably the tension in the depth-setting member, caused by the positioning of the depth-setting member on the buoyant platform and the positive buoyancy of the buoyant platform is sufficient to limit movement of the apparatus within the body of water.

Preferably the depth-setting member comprises a substantially non-elastic material. Preferably the substantially non-elastic material comprises one selected from the range: steel rope, nylon rope, Dyneema (RTM) rope. In order to achieve optimal tension in the depthsetting member and minimal movement of the apparatus in the body of water, the depthsetting member preferably comprises a mooring line which is substantially non-elastic.

Preferably the connection member defines a connection distance between the buoyant platform and the wind energy converter, wherein in the in-use configuration, the connection distance is greater than the depth. In accordance with preferable embodiments, the connection distance defined by the connection member is greater than the depth of the buoyant platform in the in-use configuration.

Preferably the wind energy converter comprises a wind turbine. Preferably the wind turbine is a horizontal axis wind turbine. Preferably the wind turbine comprises a tower, a nacelle and a plurality of blades; and wherein in the in-use configuration, the tower of the wind turbine is substantially above the surface of the body of water. Embodiments will be appreciated wherein the wind energy converter may comprise a vertical axis wind turbine, or a kite power wind energy converter.

Preferably at least a portion of the connection member comprises a reticulated frame arranged to permit passage of water substantially through the connection member.

The term “reticulated frame” will be understood by the skilled addressee to mean a mesh-like structure, which may preferably be similar in structure to common electricity pylons. Preferably the reticulated frame has a plurality of holes and is arranged to be penetrable by a medium, such that resistance to movement of said medium is minimised. In the context of the present invention, in the in-use configuration the medium is preferably water. In embodiments comprising a transport and maintenance configuration, in said configuration the medium is preferably air. Minimising resistance to movement of the medium preferably provides stability to the apparatus in normal use and in, for example, stormy conditions, turbulent sea conditions.

The term “arranged to permit passage of water substantially through the connection member” will be understood to mean water can pass from at least one side of the connection member to another.

Preferably the connection member comprises a storage cavity arranged to store equipment. Preferably in the in-use configuration, the storage cavity is located substantially above the surface of the body of water.

The connection member, providing a gap between the wind energy converter and the buoyant platform, preferably comprises space within the gap, a cavity, arranged to accommodate equipment. Preferably the equipment aids the installation, maintenance and repair of the apparatus. In some embodiments, it may be beneficial that said equipment remain substantially dry. As such, in some preferable embodiments, the equipment may be stored at a position which, in the in-use configuration, is located substantially above the surface of the body of water.

Preferably at least a portion of the buoyant platform comprises a reticulated frame arranged to permit passage of water substantially through the buoyant platform.

Preferably the buoyant platform comprises a frame arranged to minimise the resistance to the flow of a medium and thus limits the likelihood of movement of, and/or forces upon, the apparatus. Said reduced movement and/or forces preferably provides a greater stability in the apparatus and may reduce tension in any depth-setting member.

Preferably at least one of:

the buoyant platform length;

the buoyant platform width;

the buoyant platform diameter;

is selected from the range 20 to 200 metres.

Preferably the apparatus further comprises a transport and maintenance configuration, wherein in the transport and maintenance configuration, the buoyant platform is arranged to float on the surface of the body of water. Preferably in the transport and maintenance configuration, the wind energy converter is arranged to convert wind energy to the useful energy. Preferably the transport and maintenance configuration describes the relationship between the buoyant platform and the surface of the water. In embodiments comprising a depth-setting member, which requires that the buoyant platform be anchored to the bed of the body of water prior to setting the depth of the buoyant platform in said body of water, embodiments are conceivable wherein the depth-setting member optionally may or may not be in communication with the bed of the body of water while the apparatus is in the transport and maintenance configuration. In embodiments comprising such a depth-setting member, the depth-setting member may not be in communication with the bed of the body of water while the apparatus is being transported in said configuration.

Preferably, in the transport and maintenance configuration the wave energy converter is above surface of the body of water.

The transport and maintenance configuration is preferably arranged to be used when the apparatus of the present invention is undergoing maintenance or repair on-site, or being transported to the desired site at which the apparatus will be installed. Preferably said floating of the buoyant platform provides for easy transport of the apparatus, which may be by towing, while the apparatus is in the transport and maintenance configuration. Preferably while the apparatus is being transported, maintained or repaired, wherein said maintenance or repair is being performed on an element other than the wind energy converter, the wind energy converter is preferably arranged to convert wind energy to the useful energy. In embodiments comprising a wave energy converter, the wind energy converter is preferably arranged to remain functional during maintenance and repair of said wave energy converter.

Preferably, in the transport and maintenance configuration all working parts are above surface of the body of water. Preferably having all working parts above the surface of the body of water in the transport and maintenance configuration enables easier maintenance and transport of the apparatus.

Preferably the apparatus comprises a power umbilical arranged to transport energy to an energy grid and/or an energy storage device.

Preferably the buoyant platform comprises an adaptable buoyancy, wherein the buoyancy of the buoyant platform can be adjusted to position the buoyant platform at a desired depth in the body of water. Preferably the adaptable buoyancy can be used in conjunction with the adaptable depth-setting member to adjust the depth of the buoyant platform. Preferably the buoyancy of the buoyant platform can be adapted by altering the ratio of air to liquid comprised within buoyant portions of the buoyant platform.

In accordance with a second aspect of the present invention, there is provided a buoyant energy converting apparatus for converting energy obtained from renewable energy sources to useful energy, the apparatus comprising:

a wind energy converter;

a buoyant platform arranged to support the wind energy converter in a body of water having a surface and a bed; and a connection member comprising a rigid framework, the connection member being positioned between the wind energy converter and the buoyant platform and arranged to provide a gap between the wind energy converter and the buoyant platform, wherein the buoyant platform comprises an in-use configuration in which the buoyant platform is submerged in the body of water, and wherein in the in-use configuration the connection member protrudes through the surface of the body of water such that the wind energy converter is located substantially above the body of water.

Preferably the apparatus is a floating wind apparatus. More preferably, the apparatus is a tension leg floating wind apparatus.

Preferably the apparatus of the second aspect of the invention may incorporate any features of the apparatus according to the first aspect of the present invention.

Detailed Description

Specific embodiments will now be described by way of example only, and with reference to the accompanying drawings, in which:

FIG. 1 shows an isometric view of an example embodiment of a buoyant energy converting apparatus in accordance with the first and second aspects of the present invention;

FIG. 2 shows a side view of the example embodiment of the buoyant energy converting apparatus from FIG. 1 in a transport and maintenance configuration;

FIG. 3 shows a side view of the example embodiment of the buoyant energy converting apparatus from FIG. 1 in an in-use configuration in calm seas;

FIG. 4 shows a side view of the example embodiment of the buoyant energy converting apparatus from FIG. 1 in a storm configuration; and

FIG. 5 shows an example wave energy converter suitable for use with a buoyant energy converting apparatus in accordance with the first and second aspects of the present invention.

Referring to FIG. 1, an isometric view of an example embodiment of a buoyant energy converting apparatus 10 in accordance with the first and second aspects of the present invention is shown, positioned within a body of water (not shown) having a surface (not shown) and a bed 11. The apparatus comprises a wind turbine 12, a buoyant platform 14 and a connection member 16 therebetween. The wind turbine 12 comprises an elongate tower 14 having a first end coupled to a nacelle 16 having a longitudinal axis arranged orthogonally to the longitudinal axis of the tower 18, the nacelle 20 housing a rotational generator (not shown). Coupled to, and extending from, the generator are a plurality of blades 22 arranged in a plane substantially parallel to the longitudinal axis of the tower 18. The tower 18 further comprises a second end coupled to a first end of the connection member 16.

The connection member 16 comprises a lattice framework forming a substantially rectangular frustum, said first end of which having a first end aspect ratio, and a second end having a second end aspect ratio, wherein the first end aspect ratio is smaller than the second end aspect ratio. The second end of the connection member 16 is coupled to a central region of an uppermost surface of the buoyant platform 14.

The buoyant platform 14 comprises a planar structure comprising a substantially rectangular lattice framework 24, and positioned approximately at each of the four corners of the lattice framework 24 is a float (buoyancy chamber) 26. The longitudinal axis of the buoyant platform 14 is oriented substantially orthogonal to the longitudinal axes of the connection member 16 and the wind turbine 12.

Located approximately at each of the four corners of the lattice framework 24 of the buoyant platform 14 are an adaptable depth-setting means 28. The adaptable depth-setting member 28 comprises a winch 30, having a cylindrical drum, around which is wound two flexible mooring lines 32. The flexible mooring lines 32 are shown extending from the drum of the winch 30 toward the bed 11 of the body of water, and are each affixed to a respective anchoring member 34.

Positioned on the uppermost surface of the buoyant platform 14, and affixed thereto, are wave energy converters, each comprising an energy capturing float 38, a coupling member 40, and a wave energy converter 42. The coupling member 40 takes the form of a flexible line and is wound around a drum of a rotational generator located on the wave energy converter 42. The coupling member 40 is shown extending from the drum to the float 38, and is affixed thereto. The drum of the rotational generator is further enabled to be driven by a winch (not shown), which is arranged to adjust the length of the coupling member 40 and thus the proximity of the float 38 to the buoyant platform 14 or the surface 48 of the body of water 50.

The buoyant platform 12 further comprises a power transport mechanism 44 arranged to transfer energy converted from wind energy by the wind turbine 12, and/or wave energy by the wave energy converter, to an undersea connector 46. The undersea connector 46 is further connected to an undersea power export cable (not shown) leading to an electricity grid. In additional embodiments, the underseas connector may be connected to an energy storage means (not shown).

Referring to FIG. 2, the example embodiment of a buoyant energy converting apparatus 10 of FIG. 1 is shown in a transport and maintenance configuration. In the transport and maintenance configuration of FIG. 2, the buoyant platform 14 is located substantially at the surface 48 of the body of water 50. In the transport and maintenance configuration shown, the floats 38 of the wave energy converter are positioned at the buoyant platform 14 and the wind turbine 12 is positioned such that the wind turbine 12 can convert wind energy to the useful energy in the transport and maintenance configuration.

Referring to FIG. 3, the example embodiment of a buoyant energy converting apparatus 10 of FIG. 1 is shown in an in-use configuration during mild sea conditions. In the in-use configuration shown, the buoyant platform 14 is submerged beneath the surface 48 of the body of water 50, with the mooring lines 32 of the depth-setting member 28 affixed to their respective anchoring members 34 on the bed 11 of the body of water 50. In the in-use configuration shown, the connection member 16 is shown protruding through the surface 48 of the body of water 50, such that the wind turbine 12 is above the surface 48 of the body of water 50, and is not in contact with the body of water 50. The connection member 16 is shown having a cavity 52 which remains substantially above the surface 48 of the body of water 50 and is arranged to accommodate equipment (not shown). In the in-use configuration shown, the floats 38 of the wave energy converter are positioned proximate the surface 48 of the body of water 50 to capture wave movement.

Referring to FIG. 4, the example embodiment of a buoyant energy converting apparatus 10 of FIG. 1 is shown in a storm configuration during a storm, depicted in the embodiment shown by large waves. In the storm configuration shown, the buoyant platform 14 is positioned substantially as it is in the in-use configuration, submerged beneath the surface 48 of the body of water 50, with the mooring lines 32 of the depth-setting member 28 affixed to their respective anchoring members 34 on the bed 11 of the body of water 50. As with the in-use configuration of FIG. 3, in the storm configuration shown in FIG. 4, the connection member 16 is shown protruding through the surface 48 of the body of water 50, such that the wind turbine 12 is above the surface 48 of the body of water 50, and is not in contact with the body of water 50. The floats 38 of the wave energy converter are positioned at the buoyant platform 14 in the storm configuration and are thus optimised for minimum resistance of the apparatus against the large waves, minimising forces on the apparatus and tension of the mooring lines 32 of the depth-setting member 28, and maximum stability of the apparatus 10.

An example of a wave energy converter 54 is shown in FIG. 5, the wave energy converter 54 comprising an energy capturing float 38, energy conversion means 42, and a coupling member 40 coupling the float 38 to energy conversion means 42. The coupling member 40 comprises a flexible line wound around a drum within the energy conversion means 42, the drum being driven by a winch arranged to adjust the distance between the float 38 and the buoyant platform 14. As the floats 38 are moved by waves they alternately extend and contract their respective coupling members 40 and actuate the respective energy conversion means 42, enabling the apparatus to generate power. This type of wave energy converter is exemplary, and other types of wave energy converters could be used on the apparatus.

Also shown in FIG. 5 are mooring winches 30 arranged in pairs of one vertical and one angled mooring line 32 on the corners of the buoyant platform 14, however other winch positions are possible.

The wave energy converter in the described embodiments should be considered as being for the purpose of exemplification only. For the purpose of illustration, a wave energy converter similar to the Marine Power Systems WaveSub (RTM) has been described. Additional embodiments comprising different wave energy converters will be conceivable.

The embodiments described show a typical horizontal axis wind turbine, although additional embodiments will be appreciated wherein other types of wind energy capturing devices are used as, as part of, and/or within the wind energy converter, such as, for example, a vertical axis wind turbine, or a kite powered generator system.

The structure of the device is designed so that only relatively thin framework is in the wave zone when the apparatus is in its in-use configuration, reducing wave loads on the device.

To survive storms the floats of the wave energy converter can be retracted against the main structure of the buoyant platform, leaving a large gap between the floats/platform and the wind turbine tower, through which large surging storm waves can pass with minimal loads on the device.

The depth-setting member depicted in the described embodiments comprises four vertical mooring lines and four angled mooring lines to provide a high level stability to the barge platform. Additional embodiments will be appreciated wherein alternative mooring layouts are possible.

The energy transport means in the embodiment shown takes the form of a power umbilical, which exports power from the device to an underwater energy storage member, which in the embodiment shown is a junction box. From the junction box a further cable (not shown) delivers the energy to land.

In the transport and maintenance configuration shown in FIG. 2, all moving parts of the apparatus and connections are above the surface of the body of water, and can be accessed for maintenance. The floats on the buoyant platform, which are buoyancy tanks on the embodiment shown, provide the buoyancy needed to float the entire apparatus, and are of fixed buoyancy. Additional embodiments will be appreciated wherein the buoyant portions of the buoyant platform are of either fixed or variable buoyancy.

Whilst in the transport and maintenance configuration, if the apparatus is in the desired location and the power umbilical is connected, the wind turbine can remain operational when the wave energy converters are not. This allows, for example, maintenance to be carried out on the wave energy converters whilst the wind turbine still generates power.

In the in-use configuration described and shown in FIG. 3, the buoyant platform is submerged to a level which allows the wave energy converters to function and generate energy. The wave energy converters may be on or close to the surface of the body of water and can be moved by waves. The wind turbine remains clear of the water in this configuration and can be accessed for maintenance whilst the wave energy converters continue to generate power.

Embodiments may be appreciated wherein the depth-setting member, or parts of the depthsetting member are preinstalled at the desired location of the apparatus prior to transport of the apparatus to said site. In such an example situation, to deploy the apparatus in the into its in-use configuration from its transport and maintenance configuration, the apparatus is connected to preinstalled mooring lines which are attached to the bed of the body of water by respective anchoring members. The mooring lines are adjusted in length by winches on the depth-setting member. The winches reel-in the mooring lines to pull the buoyant platform beneath the surface of the body of water, overcoming the buoyancy in buoyant portions of the buoyant platform, to position the buoyant platform at a required depth.

In the storm configuration, the floats of the wave energy converters are retracted further underwater and preferably secured against the buoyant platform. The depth of the floats underwater in the storm configuration is such that they are protected from large forces that could otherwise be experienced on or close to the sea surface in storm waves. The connection member protrudes through the surface of the body of water such that it is high enough above the surface that storm waves are unable to reach the wind turbine tower. Therefore, the only part of the device that is ever exposed to storm waves is the framework of the connection member, which is made from a lattice structure, comprising beams having a thin cross section which allows waves to pass freely through its structure without experiencing high forces.

It will be appreciated that the above described embodiments are given by way of example only and that various modifications thereto may be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A buoyant energy converting apparatus for converting energy obtained from renewable energy sources to useful energy, the apparatus comprising:

a wind energy converter;

a buoyant platform arranged to support the wind energy converter in a body of water, the body of water having a surface and a bed; and a connection member comprising a rigid framework, the connection member being positioned between the wind energy converter and the buoyant platform, wherein the buoyant platform comprises an in-use configuration in which the buoyant platform is submerged in the body of water, and wherein in the in-use configuration the connection member protrudes through the surface of the body of water such that the wind energy converter is located substantially above the body of water;

wherein the apparatus further comprises a wave energy converter in communication with the buoyant platform, the wave energy converter being arranged to convert wave energy from the body of water to the useful energy.

2. A buoyant energy converting apparatus as claimed in claim 1, wherein the wave energy converter comprises an energy capturing member coupled to the energy converting member.

3. A buoyant energy converting apparatus as claimed in claim 2, wherein in the in-use configuration, the energy capturing member is positioned at or proximate the surface of the body of water.

4. A buoyant energy converting apparatus as claimed in claim 3, wherein the apparatus further comprises a storm configuration, wherein in the storm configuration, the energy capturing member is positioned at, within, or proximate the buoyant platform.

5. A buoyant energy converting apparatus as claimed in claim 2, claim 3 or claim 4, wherein the energy capturing member is coupled to the energy converting member by an adaptable coupling member defining a distance between the energy capturing member and the energy converting member.

6. A buoyant energy converting apparatus as claimed in claim 5, wherein the wave energy converter is arranged to convert relative movement between said energy converting member and said energy capturing member to the useful energy.

7. A buoyant energy converting apparatus as claimed in any one of claims 2 to 6, wherein the energy capturing member comprises a float.

8. A buoyant energy converting apparatus as claimed in any one of claims 1 to 7, wherein in the in-use configuration, the apparatus is arranged to convert both wave energy and wind energy to the useful energy.

9. A buoyant energy converting apparatus as claimed in any one of claims 1 to 8, wherein the buoyant platform comprises an adaptable depth-setting member arranged to define, over a predetermined range:

10. A buoyant energy converting apparatus as claimed in claim 9, wherein the buoyancy of the buoyant platform is arranged to provide an adequate tension in the depth-setting member, wherein the adequate tension provides a stability to the buoyant platform when in the in-use configuration.

11. A buoyant energy converting apparatus as claimed in claim 10, wherein the stability and tension in the depth-setting member is arranged to substantially inhibit movement of the buoyant platform.

12. A buoyant energy converting apparatus as claimed in claim 9, claim 10 or claim 11, wherein the depth-setting member comprises a substantially non-elastic material.

13. A buoyant energy converting apparatus as claimed in any one of claims 1 to 12, wherein the connection member defines a connection distance between the buoyant platform and the wind energy converter, wherein in the in-use configuration, the connection distance is greater than the depth.

14. A buoyant energy converting apparatus as claimed in claims 1 to 13, wherein the wind energy converter comprises a wind turbine.

15. A buoyant energy converting apparatus as claimed in claim 14, wherein the wind turbine comprises tower, a nacelle and a plurality of blades; and wherein in the in-use configuration, the tower of the wind turbine is substantially above the surface of the body of water.

16. A buoyant energy converting apparatus as claimed in any one of claims 1 to 15, wherein at least a portion of the connection member comprises a reticulated frame arranged to permit passage of water substantially through the connection member.

17. A buoyant energy converting apparatus as claimed in any one of claims 1 to 16, wherein the connection member comprises a storage cavity arranged to store equipment.

18. A buoyant energy converting apparatus as claimed in claim 17, wherein in the in-use configuration, the storage cavity is located substantially above the surface of the body of water.

19. A buoyant energy converting apparatus as claimed in any one of claims 1 to 18, wherein the at least a portion of the buoyant platform comprises a reticulated frame arranged to permit passage of water substantially through the buoyant platform.

20. A buoyant energy converting apparatus as claimed in any one of the preceding claims, wherein at least one of:

a. the buoyant platform length;

b. the buoyant platform width;

c. the buoyant platform diameter;

is selected from the range 20 to 200 metres.

21. A buoyant energy converting apparatus as claimed in any one of claims 1 to 20, wherein the apparatus further comprises a transport and maintenance configuration, wherein in the transport and maintenance configuration, the buoyant platform is arranged to float on the surface of the body of water.

22. A buoyant energy converting apparatus as claimed in claim 21, wherein the in the transport and maintenance configuration the wave energy converter is above surface of the body of water.

23. A buoyant energy converting apparatus as claimed in claim 21 or claim 22, wherein in the transport and maintenance configuration, the wind energy converter is arranged to convert wind energy to the useful energy.

24. A buoyant energy converting apparatus as claimed in claim 21, claim 22 or claim 23, wherein the in the transport and maintenance configuration all working parts are above surface of the body of water.