Patent Publication Number: US-2022213871-A1

Title: Ducted wind turbine and support platform

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 16/342,138, filed Apr. 15, 2019, which is a U.S. national phase application under 35 U.S.C. § 371 of International Application No. PCT/G82017/053186, filed Oct. 20, 2017, which claims priority to United Kingdom Application No, G81617803.0, filed Oct. 21, 2016, the entire disclosures of each of which are hereby incorporated by reference in their entirety for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a ducted wind turbine, particularly, but not exclusively, a ducted wind turbine for use in offshore environments. A semi-submersible support platform, wave energy capture apparatus and a torsional support bearing for use with or without the ducted wind turbine is also described. The present invention also includes a land-based ducted wind turbine. 
     BACKGROUND OF THE INVENTION 
     In recent years there has been an increased demand for electricity generated by renewable energy sources such as wind turbines. With this a consequential increased demand for efficiency in such turbines has led to turbines being developed with increasingly longer blade lengths. For example, wind turbines having a blade length of over 80 metres, and an associated power generation capacity in the region of 8 MW exist. 
     However, it is generally accepted that the size and power generating capacity of such turbines cannot continue to increase. This is due to there being numerous factors which are likely to eventually place effective limitations on the size and power generating capacity of such turbines; for example, materials engineering may not continue to provide materials which are able to withstand the aerodynamic, dynamic and static forces placed upon such large structures; socio-political pressures may make the erection of such large turbines impossible; other logistical or manufacturing reasons may make such structures non-viable or too expensive. 
     Offshore wind, wave and tidal turbines have been developed with a view to addressing these and other issues; however, many such turbines have poor survivability prospects in the inherently harsh environmental conditions likely to be experienced during their power generating lifetime. Indeed, it is the largest amplitude waves and strongest winds that have the potential to generate the most electrical power in such devices; however, many known systems require to be shut down, parked or otherwise secured during such conditions to avoid being damaged. 
     BRIEF SUMMARY 
     According to one embodiment of the present invention there is provided a wind energy power generating device for flotation on a body of water comprising:
         a turbine assembly including a plurality of rotor blades rotating about a rotation axis for harnessing kinetic energy from an airflow;   wherein the cowl is rotatably mounted on the base platform such that it is rotatable around the turbine assembly to self-align with the prevailing wind direction; and   a base platform adapted to support the turbine assembly and the cowl on a body of water;   wherein the cowl is mounted on the base platform by way of a weathervane bearing arrangement such that the cowl may weathervane around the turbine assembly in response to changes in a wind direction;   wherein the inlet axis and the outlet axis intersect with one another at a redirect angle α;   and wherein four or more stabilising arms extend away from the base platform and are mutually equally spaced circumferentially around a platform axis, to thus stabilise it on a body of water.       

     Optionally, the redirect angle a is between 90 and 170 degrees. 
     Optionally, the platform axis extends through a centre of gravity of the wind energy power generating device. 
     Optionally, the rotation axis of said plurality of rotor blades extends through the base platform. 
     Optionally, the rotation axis of said plurality of rotor blades is coaxial with the platform axis. 
     Optionally, the number of stabilising arms is between 5 and 12. 
     Optionally, some or all of the stabilising arms are provided with at least one buoyant hull member for providing buoyancy to cause or assist with flotation of the base platform and the turbine assembly and cowl supported thereon. 
     Optionally, each buoyant hull member may be attached to its stabilising arm at any position along its length between its proximal end nearest the base platform; and its end most distal to the base platform. 
     Optionally, each buoyant hull member may be directly attached to its stabilising arm; or each buoyant hull member may be indirectly attached to its stabilising arm via a connecting leg. 
     Optionally, each stabilising arm extends away from the base platform perpendicularly with respect to its platform axis. 
     Alternatively, some or all of the stabilising arms extend both away from, and downwards relative to, the base platform such that the longitudinal axes of said stabilising arms intersect with said platform axis at an acute angle β. 
     Optionally, each stabilising arm is fixedly connected to the base platform. 
     Alternatively, some or all of the stabilising arms are pivotably connected to the base platform to allow variation of an intersect angle β between their longitudinal axes and said platform axis within a range of +90 degrees (horizontal) and −80 degrees (beyond vertical). 
     Optionally, each connecting leg is fixedly connected to its associated stabilising arm. 
     Alternatively, some or all of the connecting legs are pivotabiy connected to their associated stabilising arm to allow angular optimisation of each connecting leg dependent on the angular position of said stabilising arm relative to said platform axis. 
     Optionally, the cross-sectional area of each stabilising arms and/or each connecting leg diminishes with increasing distance from the platform axis. 
     Optionally, each stabilising arm and/or each connecting leg comprises an internal void for receiving ballast water to cause angular movement thereof between two or more alternative positions relative to the platform axis. 
     Additionally, or alternatively, each stabilising arm and/or each connecting leg is moveable between two or more alternative angular positions relative to the platform axis by means of adjustable tensioning members in the form of lines, struts, or tie bars. 
     Optionally, the plurality of rotor blades in the turbine assembly are assembled on sets of co-axial contra-rotating hubs such that a primary set of rotor blades rotates around the rotational axis in one direction and a secondary set of rotor blades rotates around said rotational axis in an opposite direction. 
     According to another embodiment of the present invention there is provided a wind energy power generating device secured to the ground or other fixed and non-floating structure, comprising:
         a turbine assembly including a plurality of rotor blades rotating about a rotation axis for harnessing kinetic energy from an airflow;   wherein the cowl is rotatably mounted on the base platform such that it is rotatable around the turbine assembly to self-align with the prevailing wind direction; and   a base platform adapted to support the turbine assembly and the cowl;   wherein the cowl is mounted on the base platform by way of a weathervane bearing arrangement such that the cowl may weathervane around the turbine assembly in response to changes in a wind direction; and   wherein the inlet axis and the outlet axis intersect with one another at a redirect angle α.       

     Optionally, the redirect angleα is between 90 and 170 degrees. 
     Optionally, the plurality of turbine rotor blades are respectively assembled on sets of coaxial contra-rotating hubs such that a primary set of rotor blades rotates around a rotational axis in one direction and a secondary set of rotor blades rotates around said rotational axis in an opposite direction. 
     Further features and advantages of the embodiments of the present invention will become apparent from the claims and the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present invention will now be described by way of example only, with reference to the following diagrams, in which: 
         FIGS. 1A and 2  are schematic perspective side view illustrations of a ducted wind turbine mounted on an associated semi-submersible platform; 
         FIG. 1C  is a schematic perspective side view illustration of an alternative example of a floating ducted wind turbine; 
         FIG. 1B  is a schematic transverse illustration of an alternative linked floatation hull arrangement; 
         FIG. 3A  is a schematic plan view illustration of the turbine of  FIGS. 1A and 2 ; 
         FIGS. 3B and 3C  are schematic plan views of example alternatively shaped support platform and flotation arrangements; 
         FIG. 4A  is a transverse partial cross-sectional schematic illustration of the turbine of  FIGS. 1A and 2 ; 
         FIG. 4B  is a transverse partial cross-sectional schematic illustration of the turbine of  FIG. 1C ; 
         FIG. 5  is a more detailed schematic illustration of a turbine blade, hub and internal tower arrangement of the turbine of  FIGS. 1A and 2 ; 
         FIG. 6  is a more detailed schematic illustration of an alternative example of the turbine where the internal tower profile has a narrowed cross section; 
         FIG. 7A  is a more detailed schematic front illustration of a railway axle and associated railings of  FIGS. 5 and 6 ; 
         FIG. 7B  is a plan view schematic illustration of the arrangement in  FIG. 7A ; 
         FIG. 8A  is a schematic plan view illustration showing an alternative turbine tower in accordance where two example turbine blade formations are illustrated attached thereto; 
         FIG. 8B  is a schematic perspective view illustration showing a portion of the turbine tower of  FIG. 8A ; 
         FIG. 8C  is schematic perspective view illustration showing an upper portion of the turbine tower of  FIG. 8A  in greater detail; 
         FIG. 9A  is a lower perspective schematic illustration of an alternative wave energy absorber attached to a torsional bearing arrangement; 
         FIG. 9B  is a more detailed illustration of the torsional bearing arrangement of  FIG. 9A ; 
         FIG. 10  is a schematic diagram illustrating the basic principle of operation of the wave energy absorber; 
         FIG. 11  is a perspective illustration of the arrangement in  FIG. 3  where a pair of additional inclined axis water turbine arrangements extend from the trailing edge of the arrangement; 
         FIG. 12A  is a more detailed plan view schematic illustration of an inclined axis water turbine arrangement and its associated components; and 
         FIG. 12B  is a transverse schematic illustration of the arrangement shown in  FIG. 12A , 
         FIG. 13  is a schematic plan view of the floating wind energy power generating device according to a first embodiment of the present invention; 
         FIG. 14  is schematic perspective side view of the base platform of the device of  FIG. 13  showing optional cross-braces between adjacent legs, and optional tensioning members; 
         FIG. 15  shows an alternative base platform structure showing downwardly inclined stabilising arms; 
         FIGS. 16A-B  show two alternative arrangements for moving stabilising arms of the base platform between a launch position and a deployed position; and 
         FIGS. 17A-B  shows two alternative examples for the structure of the stabilising arms. 
     
    
    
     DETAILED DESCRIPTION 
     With particular reference to  FIGS. 1 to 3  an offshore power generating module generally designated  10  comprises a floating ducted wind turbine (DWT) generally designated  12  mounted upon a semi-submersible platform (SSP) generally designated  14 . 
     The DWT  12  comprises a contoured and shaped outer cowl  16  which is aerodynamically contoured on its inner side to facilitate smooth flow of air flow therethrough with minimal energy loss, and aerodynamically contoured on its outer side to minimise structural loads and aerodynamic turbulence on the DWT  12  and the SSP  14  upon which it is mounted. Downstream from the cowl  16  is an intermediate empennage section  18  which tapers from the cowl  16  to an associated vertical stabiliser  20 . 
     Several types and format of material may be utilised in order to form the cowl  16 , empennage  18  and tail  20  section; however, examples include sail cloth, fibreglass, geodetic structures etc. 
     The outer cowl  16  gradually and aerodynamically tapers from a rectangular section inlet duct  22  at its in-use front end to a circular section outlet duct  24  at its upper surface. Tapered cut-outs (not shown) may be provided in the side walls of the cowl  16  adjacent the inlet  22  in order to facilitate entry of any off-centred gusts encountered. As shown in  FIG. 4 , the inlet duct  22  is provided with a longitudinal axis L 1  and the outlet duct  24  is provided with a longitudinal axis L 2 . In conforming from the rectangular shaped section adjacent inlet duct  22  to the circular shaped section adjacent outlet duct  24 , the cowl  16  turns through a redirect angle α ( FIG. 4 ) this being the angle between the two axes L 1  and L 2 . In the embodiment illustrated this redirect angle α is in the region of 100 degrees; however, it may be far lesser or greater depending upon requirements. 
     As best illustrated in  FIGS. 2 and 4A , the internals of cowl  16  also comprises a series of horizontally arranged air flow guide vanes  26  and a central vertically arranged air flow baffle  28 . 
     With particular reference to  FIG. 4A , inside the DWT  12 , a main air duct  25  is provided and the guide vanes  26  are gradually curved from the longitudinal axis L 1  toward the outlet longitudinal axis L 2  in order to similarly direct the flow of air passing therethrough. The vertical separation distance between the guide vanes  26  also gradually increases as they progress from the inlet duct  22  toward the outlet duct  24  in order to promote smooth airflow and facilitate an even distribution of air toward the outlet  24 . An optional diffuser wing  27  may be provided at a suitable distance above the DWT outlet  24  in order to advantageously interact with the airflow exhausted therefrom in order to maximise the efficiency of the apparatus (as represented by lines F in the area D in  FIG. 4A ). The upper surface of the diffuser wing  27  may also be provided with an array of photovoltaic cells in order to allow further energy capture from solar energy if desired. 
     A contra-rotating turbine assembly (CRTA)  30  projects into the main air duct  25 . With reference to  FIG. 5 , the CRTA  30  includes a primary set of turbine blades  32  and a secondary set of turbine blades  34  which are arranged such that they are contra-rotating relative to one another. The primary blades  32  are mounted upon a primary tower  36  and the secondary blades  34  are mounted upon a secondary tower  38  which is coaxially surrounded by the primary tower  36  (the primary and secondary towers are shown in partial cut away section for illustrational purposes in  FIG. 5 ). With the blade orientation illustrated in  FIG. 5 , the primary blades will rotate in the clockwise direction (when viewed from above) and the secondary blades will rotate in an anti-clockwise direction (when viewed from above) when the airflow A passing through the DWT  12  is imparted on them; however, these directions may be altered by changing the blade orientations as desired. Furthermore, an active blade pitch adjustment mechanism may be utilised if desired. 
     With reference to  FIG. 6 , in an alternative embodiment, the cross section of the main air duct  25  at or adjacent the CRTA  30  may comprise a narrowed section in order to provide altered flow dynamics represented by arrows A 1  through the DWT  12 . 
     In the embodiments illustrated by  FIGS. 5 and 6 , the primary and secondary sets of blades  32 ,  34  are not rotationally mounted on their respective towers  36 ,  38 . Instead the sets of blades  32 ,  34  are rigidly mounted to their respective towers  36 ,  38  and the towers  36 ,  38  are rotationally mounted on their respective bases at a power deck module  40 . However, in an alternative embodiment, the reverse can be achieved by locating the bearings and electricity generators (discussed subsequently) at the same height as the turbine blades atop the towers if required. 
     In the embodiment illustrated in  FIGS. 5 and 6 , the towers  36 ,  38  comprise a latticework space frame structure having curved members arranged so as to provide a circular outer cross section; however, any alternative structure may be utilised as appropriate. The power deck module  40  may be mounted onto a concrete plinth or base. Ancillary systems for hydrogen production, CO2 capture, and energy storage (e.g. a water tower inside the towers  36 ,  38 ; or a flywheel modification) may also be included as part of the overall device. 
     With reference to  FIG. 8A , in an alternative embodiment a turbine tower  136  (which may be a primary or secondary turbine tower) comprises a multi-faceted latticework space frame structure. In the embodiment illustrated the cross section of the structure is shown as being hexagonal; however, any number of straight sides may be provided in order to form the required 360-degree formation of the tower. Each cell of the latticework comprises an outer face strut  136 A, inner face strut  136 B, and diagonal cross bracing strut  136 C. Where for example the lengths of the outer face struts  136 A are in the region of 6 metres around 40 flat faces may be provided around the circumference of the tower  136  in order to provide a 360-degree assembly. 
     With reference to  FIG. 8B , each cell of latticework is mounted upon and adjacent to similarly arranged cells in order to provide a double walled multi-faceted latticework tower. 
     With reference to  FIG. 8C , turbine blades  132  are attached to the cells of the tower  136  by way of one or more blade root rods  135 . In use, when the turbine blade is driven in the direction indicated by arrow A in  FIG. 8C  the blade root rod  135  creates a coupled force T 1  and T 2  and imparts a rotational force F on the tower  136  which in turn generates electrical power by driving electricity generating modules (not shown). 
     The lattice framework arrangement described with reference to  FIGS. 8A to 8C  minimises the primary and/or secondary tower overall mass, material and construction costs. 
     The structures referred to above may be provided with a drag reducing aerodynamic skin if required in order to minimise disruption to the air flowing there past within the main duct of the DWT  12 . 
     Referring again to  FIGS. 5 and 6 , the power deck module  40  comprises a primary set of roller bearing assemblies  42  and a primary electricity generator  44  which are associated with the primary tower and hence the primary blades  32 . Likewise, for the secondary tower  38  the power deck module  40  also comprises a secondary set of roller bearing assemblies  46  and a secondary electricity generator  48  which are associated with the secondary tower and hence the secondary blades  34 . 
     With reference to  FIGS. 7A and 7B , the roller bearing assemblies  42 ,  46  comprise a pair of wheel sets  48  which are located within a bogey arrangement  50  by resilient spring/damper arrangements  52  in order to allow the wheel sets  48  to follow a circular curved section of associated track  54 . 
     The electricity generators  44 ,  48  comprise any suitable generator such as for example a large diameter permanent magnet and coil generator. 
     With reference to  FIG. 1A , the SSP  14  comprises a square planar upper support deck  56  having a pair of trailing wings  58  extending rearward from opposing corners of the deck  56  in older to form a resultant delta-wing shape when anchored by a tether diagrammatically represented by arrow  60  in  FIG. 1A . 
     Note that in alternative embodiments illustrated by  FIG. 3B and 3C , the SSP  14  and any associated flotation arrangement may be arranged with alternatively shaped profiles depending upon requirements. 
     Returning to the arrangement of  FIG. 1A , four hull support struts  62  project downwardly from the support deck  56  toward corresponding flotation hulls  64  provided with heave damper plates  66 . The relative dimensions of the support struts  62  and the dimensions/buoyancy of the flotation hulls  64  are dimensioned such that the support struts  62  have a relatively (in relation to the buoyancy provided by the hulls  64 ) low cross sectional area at the point at which they are likely to meet the waterline in order to maximise the stability of the support provided in accordance with “Small Waterplane Area Twin Hull” (SWATH) theory. A typical expected mean position of the waterline is indicated as W in  FIG. 4A . More or less than four hull support struts may be provided depending upon requirements. 
     With reference to  FIG. 1B , in an alternative embodiment, the floatation hulls  64 A may be linked to one another by link  65  and connected to the SSP  14  by one or more supports struts  62 A as desired. The link  65  illustrated in  FIG. 1B  is shown in-line with the longitudinal axes of the floatation hulls  64 A; however, in an alternative embodiment (not shown) the link may instead be linked perpendicular to the linked floatation hull longitudinal axes. 
     Extending rearward from the trailing wings  58  are several wave energy absorbers  68 . These are of the same length as one another so that their ends effectively mirror the delta-wing shape of the trailing wings  58  for purposes which will be described subsequently. The wave energy absorbers  68  comprise elongated arms  70  which are connected to the trailing wings  58  at one end by a pivot joint  72  and provided with a semi-spherical flotation arrangement  74  at the other end for engagement with the water surface/passing waves. 
     With reference to  FIGS. 9A and 9B , in an alternative embodiment, the wave energy absorbers comprise a combined monocoque structural arm and flotation chamber arrangement  68 A having a torsional bearing  80  and power take off connections  78  at one end thereof. The torsional bearing  80  is provided to allow pivoting attachment of the flotation chamber  68 A to the SSP  14  and comprises a central disc  76  which is rigidly connected to the flotation chamber  68 A, a pair of end discs  82  which are rigidly connected to an appropriate anchoring point on the SSP  14 , and torsional/supporting rods  84  which connect the end discs  82  to the central disc  76 . 
     Referring to  FIGS. 1 to 3 , the DWT  12  is attached to the SPP  14  by way of a rotating table arrangement generally designated  86  and comprising a circular load bearing plate  88  attached. to the underside of the DWT  14  and a corresponding circular recess  90  provided on upper deck  56  of the SSP  14 . Friction reducing means such as e.g. wheel and track arrangements similar to the roller bearing assemblies  42 ,  46  described above, or e.g. ball bearing based arrangements provide the DWT  12  with the ability to weathervane upon the SSP  14  as indicated by arrow W in response to changes in the prevailing wind direction. 
     In the described embodiments the height of the overall combined DWT and SSP structure might be in the region of around 200 to 800 metres with the wing span from tip to tip also being in the region of around 200 to 800 metres; however, the reader will appreciate that these dimensions may be greatly altered to suit the predicted forces, power generating requirements, deployment location etc. as required. 
     The offshore power generation module  10  may also be provided with tidal turbine arrangements such as vertical “across” axis turbines (as diagrammatically illustrated by  75  in  FIG. 3 ) horizontal “across” axis turbines, or axial flow turbines (as diagrammatically illustrated by  90  in  FIGS. 12 and 12A, 12B . 
     With reference to  FIGS. 12A and 12B , a combined turbine a main turbine shaft  92  is angled into the water from the SSP  14  and is provided with a turbine arrangement  94  at its lower end. The main shaft  92  and/or turbine  94  are buoyant such that any heave loads are minimised and such that radial bearing loads are reduced at the hub/pivot point. This buoyancy also supports the turbine mass and reduces any bending moment applied to the main shaft in order to reduce fatigue loads resulting from the shaft rotation. The flow into the turbine is also augmented into the turbine by fairings  96 . 
     In use, the offshore power generating module  10  is first towed into its desired waterborne operating location either by a suitable vessel or by a self-propelling motor etc. This location may be at shallow or deep-water sea, rivers, estuaries, or on inland water features such as lakes, and inlets etc. 
     Once at a suitable location, the module  10  is tethered there by any suitable anchoring arrangement as diagrammatically represented by arrow  60  in  FIG. 1A . In such a condition the prevailing water current imparted on the SSP  14  will naturally cause it to weathervane around its tether such that the SSP  14  will naturally align with the prevailing water current. 
     As a prevailing wind (which may be in a different direction from the prevailing water current) is imparted upon the DWT  14  the force of said wind will interact with the intermediate empennage section  18  and vertical stabiliser  20  in order to naturally cause the front of the DWT  14  cowl  16  to weathervane on its bearing table  86  around the turbine module into the wind as illustrated by arrow W in  FIG. 1A . 
     In this way the SSP  14  will always naturally be aligned with the prevailing water current and the DWT  12  will always naturally be aligned with the prevailing wind direction. 
     Alternatively, or additionally, the orientation of the DWT  12  cowl  16  relative to the prevailing wind direction may be controlled actively using a forward-looking sensing system, An example such system is LIDAR where LIDAR sensors are provided on or around the cowl  16 . In such an arrangement, sensing data is processed by on board or remote computer control systems and sends control responses to electro-mechanical, pneumatic, magnetic and/or hydraulic actuators in order to either directly drive the wind turbine cowl  16  into the wind or cause the components of the tail  20  to deflect and therefore cause the cowl  16  to rotate into the wind. 
     Such control systems may in some circumstances allow the cowl  16  to respond more quickly to wind direction changes than might be the case with passive weathervane control alone. The above control systems may be used in addition or independently to control or adjust any aerodynamic or other system anywhere within the system. 
     The provision of LIDAR sensors in conjunction with such a control system also allows oncoming wave and swell sea states and profiles which may interface with the power generating module  10  to be detected. When such expected conditions are detected this information is input to the system such that all responses of any components can be optimised to ensure a maximum efficiency of energy harvesting from the environment by the system&#39;s various components. For example, the resistance to movement of the wave energy absorbers can be increased when high magnitude waves are expected. This may also enhance platform stability and reduce mechanical and electrical stresses throughout the system as a whole which in turn may help to extend the lifetime of the system and reduce maintenance requirements. Such control systems and software may be pre-programmed or contain learning algorithms. Control input requirements may be generated on board the power generating module  10 , at an operator control centre or from demand side inputs (for example electricity grids or energy companies). 
     With reference to  FIG. 4A , with the duct inlet  22  of the DWT  12  facing directly into any prevailing wind, incoming airflow A will enter the main air duct  25  of the DWT through the inlet  22 , travel along and up the internal main duct  25  under the guidance of the guide vanes  26 , and will be directed upwards towards the turbine arrangement  30 . 
     With reference to  FIG. 5 , when such ducted airflow A meets the primary set of turbine blades  32  it will impart a clockwise (when viewed from above) rotational force thereupon. Since the primary blades  32  are mounted on primary tower  36  which itself is mounted upon wheel bearings  42  the primary tower  36  will rotate under the action of said rotational force. As this occurs electrical power will be generated at the primary generator  44 . 
     In a similar fashion, once the stream of air has passed the primary set of turbine blades  32  it will impart upon the secondary set of turbine blades  34  and hence impart a rotational force thereon. However, since the secondary blades  34  are orientated in the opposite sense from the primary blades  32  this will be an anti-clockwise (when viewed from above) rotation force. Since the secondary blades  34  are mounted on secondary tower  38  which itself is mounted upon wheel bearings  46  the secondary tower  38  will rotate under the action of said anti-clockwise rotational force. As this occurs electrical power will also be generated at the secondary generator  48 . 
     Throughout the above described operations, it will be appreciated that the duct or cowl assembly  16  is free to weathervane around the turbine arrangement without any rotation of the turbine rotor assembly as a whole being required. This creates a useful mechanical dissociation between the angular orientation of the duct or cowl assembly  16  from the angular orientation of the remaining components of the power generating module  10 . 
     The previously described contra-rotation of the primary blades  32  relative to the secondary blades  34  means that any torque generated by one set of blades is, in the most part, cancelled out by any torque created by the other set of blades. This results in minimum residual torque being applied to the SSP  14  upon which the DWT  12  is mounted. 
     The process of harvesting energy from the water upon which the SSP  14  is stationed will also now be described. For clarity this will be described with reference to an example passing wave and separately with reference to an example prevailing water current; however, it will be appreciated that the module is capable of harvesting energy from the wind, waves and water current simultaneously. 
     As an example, wave approaches the module  10 , its first useful interaction with it will be with the semi-spherical flotation arrangements  74  of the two foremost wave energy absorbers (e.g. the two wave energy absorbers nearest to the centreline of the SSP  14 ). With reference to  FIG. 9  as wave front W travelling in direction A interacts with the float  74  the float&#39;s inherent buoyancy will rotate the float  74  and its attached arm  70  upwards away from its neutral position (where its longitudinal axis is in position P 1 ) towards its loaded position (where its longitudinal axis is in position P 2 ). During such rotation away from the neutral position P 1 , the buoyant force of the float  74  acts to apply a torsional loading force to the torsional bearing  80  and to usefully move any power take off arrangements attached to the power take off connections  78  thereof and hence generate power. This loading of the torsional bearing  80  essentially stores a portion of the kinetic energy harvested from the upward motion of the wave energy absorber  68  as potential energy within the torsional bearing  80 . The reluctance of the SSP heave damper plates  66  to vertical movement within the water column also provides a reaction force against which the floats  74  act during this up-stroking loading phase. 
     Once the float  74  has reached the crest of the wave front W the arm  70  will be in position P 2  and the torsional bearing  80  can be considered as fully loaded for that wave front W. At this point, the wave front W begins to fall away and no longer fully support the weight of the wave energy absorber  68  such that the wave energy absorber  68  will begin to ride back down the crest of the passing wave front W. Whilst doing so, the potential energy stored within the torsional bearing  80  is released thereby facilitating said down stroking of the wave energy absorber  68 . 
     The above described transfer of kinetic energy from the up-stroking wave energy absorber  68 , to temporarily stored potential energy in the torsional bearing  80  and then back to kinetic energy in the down-stroking wave energy absorber  68  is (with the exception of power usefully extracted by the energy take offs) substantially energy neutral; however, this provides a strong support bearing having the desired pivoting abilities with minimal frictional losses. 
     Since wave profiles can generally be approximated as a mathematical sine wave, the movement profile and hence electrical power generation profile of each wave energy absorber  68  can also be generally approximated to a mathematical sine wave. As a given wave passes each wave energy absorber  68  additional sine wave energy profiles are created. This creates a set of phase-shifted energy pulses which helps to smooth the profile of the resultant energy captured by the system. This effect is further enhanced by the plurality of wave energy absorbers  68  being arranged in a delta-wing arrangement since this results in each new wave front generating sine wave energy profiles at the forward wave energy absorbers  68  whilst older passing wave fronts are still interacting with more rearward wave energy absorbers  68 . 
     The wave energy absorbers  68  may be actively controlled in order to adjust the buoyancy stiffness of each individual absorber arrangement as it is displaced upwards or downwards in response to wave and swell formations passing by the power generating module  10 . 
     The SSP  14  itself provides a very stable structure for the various components described since it is always aligned well with any prevailing water current, has a low and centralised centre of gravity, benefits from inherent geometric stabilities and makes use of the small water plane area struts/flotations and heave plates. 
     The energy simultaneously harvested by the multiple aforementioned arrangements can be accumulated by mechanical or electrical means such that conditioned and smoothed energy pulses may be fed into the electricity grid as appropriate. Example mechanical accumulators might include pneumatic or hydraulic pressure accumulators or springs or flywheels etc. Example electrical accumulators might include e.g. capacitors or batteries etc. Alternatively/additionally, the harvested energy could be utilised on-board the module  10  to useful effect such as in the production of gas (e.g. hydrogen or oxygen) or in desalination/electrolysis operations etc. 
     In addition to those previously described, the present invention also has the advantage of allowing many moving and complex mechanical parts to remain well above the water level and away from the splash zone. This results in greater expected longevity due to reduced wear and tear. 
     Furthermore, it will be appreciated that the described invention has the advantage of being configurable at virtually any scale whilst also being well suited to being provided as either a singular unit or in a field of several units. 
     Although particular embodiments of the invention have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims. 
     It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims. For example: 
     Although the embodiments described within the present application primarily refer to a 
     floating arrangement provided on a body of water, the invention is not limited to being provided on a floating platform but instead may be provided on a variety of possible foundations such as on land or ice whether the invention be directly attached to such foundations (in e.g. the case of a turbine directly resting on a piece of land) or installed on vehicles or buildings (in e.g. the case of a turbine installed atop a building). 
     The invention may be provided with control systems for maintaining the correct level of buoyancy in the floating platform and/or assimilating environmental and demand side data signals such that the turbine operational efficiency and output is maximised. This may be achieved through pre-programmed controls, learning control algorithms or any other appropriate control strategy as required. 
     In an alternative embodiment illustrated with reference to  FIG. 1C , the power generating module  210  may be provided with LIDAR sensors  212  in order to provide the LIDAR capability previously mentioned. Furthermore, the vertical stabiliser  220  is provided with a corresponding rudder control surface  221 , a horizontal stabiliser  223  and corresponding elevator control surfaces  230 . These surfaces allow the orientation of the duct or cowl  216  to be controlled in a similar fashion to the way in which an aircraft tail is able to control the yaw angle and angle of attack to the oncoming airflow. Trim-tabs may also be provided to trim out any forces required to maintain the cowl  216  in the optimal orientation with respect to the prevailing wind direction. 
     The embodiment illustrated in  FIG. 1C  is also provided with external aerodynamic vanes  225  which further facilitate aerodynamically efficient airflow over and around the cowl  216 . Leading edge aerodynamic flaps  227  are provided adjacent the inlet duct  222  and corresponding trailing edge aerodynamic flaps  229  are provided adjacent the outlet duct  224 . The flaps  227 ,  229  may be controlled and deployed by an on-board or remote-controlled system in response to any forward-looking wind or sea state sensor information (such as the aforementioned information obtained from the LIDAR system). 
       FIG. 13  shows a wind energy power generating device  300  for flotation on a body of water. The device  300  comprises a central hexagonal base platform  310  centred on a notional platform axis PX. A turbine assembly  330  (see  FIG. 14 ) is mounted on the base platform  310  and is surrounded by an aerodynamically contoured cowl  320 . The cowl  320  is rotatably mounted on the base platform  310  such that the cowl  320  may weathervane around the turbine assembly to self-align with the prevailing wind direction. Although in the example of  FIGS. 13 and 14  the platform axis PX is coincident with the rotational axis of the turbine assembly  330 , it will be appreciated that these axes need not coincide. In some embodiments, counterweights may be provided on the device to counter offset moments. 
     A cantilevered stabilising arm  312  extends radially away from each side  314  of the base platform  310 . An elongate buoyant hull member  316  is connected, directly or indirectly, to an underside of each stabilising arm  312  proximate its end most distal from the platform axis PX. All six buoyant hull members  316  are orientated such that their longitudinal axes are respectively coaxial or substantially parallel with one another. It will be appreciated that the base platform  310  may adopt the shape of any polygon with four or more sides  314 . The ratio of the number of sides  314  to the number of cantilevered stabilising arms  312  may be 1:1. However, in some embodiments the base platform  310  may have more sides  314  than it does cantilevered stabilising arms  312 . 
       FIG. 14  is a side view of the base platform of the device of  FIG. 13  with the cowl  320  shown in cross-section to reveal the turbine assembly  330  located therein. The cowl  320  defines an airflow AF passageway between a cowl inlet  324 , having an inlet axis L 1 , and a cowl outlet  326 , having an outlet axis L 2 . Internally, the airflow entering the cowl inlet  324  is re-directed through a redirection angle α, by curving vanes and/or baffles  328 , towards the cowl outlet  326 . 
     Further features and advantages of the cowl  320  and turbine assembly  324  have already been described above in connection with the embodiment of  FIG. 4A , and some or all of those features may be incorporated into the embodiment of  FIG. 14 . 
     Also shown in  FIG. 14  are legs  318  connected to the ends of each stabilising arm  312  which are most distal to the platform axis PX. Each leg  318  is directed downwardly with one of the elongate buoyant hull members  316  connected thereto. The buoyant hull members  316  are provided with heave damper plates in similar manner to those shown in  FIGS. 2 and 3A . The connection between each stabilising arm  312  and its corresponding leg  318  may be fixed or pivotable. The structural rigidity of the device  300  may be improved by providing a series of bracing members  330  braced between adjacent stabilising arms  312  and or legs  318 . Non-exclusive examples of bracing members  330  which may work in tension or compression may consist of ties, rods, struts, wires, and chains. Each leg  318  has a reduced water plane cross-sectional area. Each leg  318  may have a constant cross-section along its length, or be tapered. to influence the rate of change of buoyancy generated in response to varying wave heights. 
     Additionally, the connection between each stabilising arm  312  and its corresponding side  314  of the base platform  310  may be fixed in one position or pivotable so as to be fixable in a range of different positions. In some embodiments, a pivotable connection facilitates a variation of an intersect angle β between a longitudinal axis AX of said stabilising arms and said platform axis PX within a range of +90 degrees (horizontal) through 0 degrees vertical), and −80 degrees (beyond vertical). 
     The ability to vary the intersect angle β provides flexibility in terms of storage and transportation. The ability to fix or dynamically adjust the intersect angle β at a desired operational position(s) allows these potentially very large devices  300  to be used in different sea and/or weather conditions. For example, it is anticipated that each stabilising arm  312  and leg  318  may be assembled ‘on the flat’ in a ‘starfish’ arrangement. A potential advantage of doing so is that the device  300  may be more easily launched from gently sloping shorelines into shallow waters. This would remove the need to launch from deep water quays using heavy, and hence expensive, lifting apparatus. 
     It will be appreciated that angular optimisation of each leg  318  dependent on the angular position of said stabilising arm  312  relative to said platform axis PX is made possible by providing respective pairs of pivotable connections between each stabilising arm  312  and its corresponding side  314  of the base platform  310 ; and between each stabilising arm  312  and its corresponding leg  318 . 
     In the alternative embodiment of  FIG. 15 , an elongate buoyant hull member  316  is directly connected to an underside of each stabilising arm  312  proximate its end most distal from the platform axis PX, i.e. there are no legs  318 . The structural rigidity of the device  300  may be improved by providing a series of bracing members  330  braced between adjacent stabilising arms  312 . 
       FIGS. 16A-B  show two alternative arrangements for moving pivotable stabilising arms  312  of the base platform  310  about a pivot joint  340  between an initial launch position and an operational position. In the example of  FIG. 16A , a tension line  350  extends between the base platform and an end  312   d  of the stabilising arm  312  which is most distal relative to the base platform  310 . The tension line  350  extends over or through an intermediate guide member  360  proximate the pivot joint  240 . A pulling force PF applied to the tension line  350  associated with each stabilising arm  312  causes it to pivot downwards from an initial launch or stowed position, into a deployed or operational position for supporting the device  300  on a body of water. Each tension line  350  may be either temporarily fitted to the device  300 ; or be provided as a permanent part of the device  300 . 
     In the example of  FIG. 16B , a rigid strut or tie bar  352  is employed instead of a tension line  350 . The strut or tie bar  352  is connected, at its end most proximal to the base platform, to a winch line  354  which is connected to, and rotatable around, a spindle  356 . In like manner to the arrangement of  FIG. 16A , a pulling force PF applied to the winch line  354  caused by rotation of the spindle  356  causes each stabilising arm  312  to pivot downwards from an initial launch or stowed position, into a deployed or operational position for supporting the device  300  on a body of water. Each strut or tie bar  352  may be either temporarily fitted to the device  300 ; or be provided as a permanent part of the device  300 . 
     Movement of each stabilising arm  312  and/or leg  318  to a desired deployed or operational position can also be achieved, or assisted, by water ballasting of the buoyant hull members  316 . 
     As shown in  FIG. 17A-B , the structure of the stabilising arms  312  and legs  318  may take different forms. For example, they may be formed from box beams and/or monocoques and/or connected stress cells and/or composite constructions. Alternatively, they may be provided as a space frame of hollow or solid cross-sectional elements. Suitable construction materials may comprise (but are not limited to) metals; composite materials; bio-structural materials; and concrete with or without an aggregate mix and/or steel or glass reinforcement; or any combination of the foregoing.