Nearshore monopile mounted wave energy collector

Abstract

A wave energy system designed preferably for use near the coast with advantages comparable to shoreline devices. The system comprises of a monopile firmly secured to the seafloor and extending above the waterline. The energy extraction system is mounted on the monopile, on which it is able to travel between a lower and an upper position. The energy extraction system operates when it is lowered in the sea, or raised at the top of the monopile for maintenance or during poor weather condition. Pitching movements of the energy extraction system resulting from interaction with the waves allow energy to be harnessed. Aerial cables secured at the top of the monopiles within a group of such devices allow cost effective power transmission to the grid. Ropeways secured between the monopiles enable safe access to maintenance personnel.

Description

[0001] NEARSHORE MONOPILE MOUNTED WAVE ENERGY COLLECTOR

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to a wave energy harnessing system most suitable for installation near the coast, with advantages comparable to wave energy systems installed firmly on the shore.

[0004] BACKGROUND OF THE INVENTION

[0005] Wave energy is expected to become an important source of clean renewable energy in the near future. Many populated areas are located near oceans, and wave energy could be as competitive as most other energy sources, or even better. Wave energy is generally more reliable than both solar and wind. While presently several wave energy concepts appear to have reached advance stages of development, widespread commercialisation still appears far off.

[0006] While there is a growing global environmental awareness which encourages the development and implementation of wave energy systems, energy developers and operators appear shy to fully engage. The industry is nascent and also very fragmented. A considerable numbers of wave energy concepts have already been proposed, and the most suitable concepts may have yet to be sorted out. It is also plausible that the best concepts still remain to be found. As a result, standard practices and norms which are essential to facilitate growth of the industry have yet to emerge.

[0007] The development of wave energy may be mainly hampered because it is too disruptive from practices which are common in the energy industry, and this largely deters the interest of potential investors and operators. Energy installations are normally operated on firm ground, where the risk assessment is better understood, as opposed to installations in the open sea. Offshore wind power systems have become gradually acceptable because they are mounted on top of foundations above the waterline, hence safe to operate. But wave energy systems are mostly designed to be installed directly in the ocean, which make them dangerously exposed to destructive waves during storms. Another discouraging factor is the complexity to install and operate such installations in the open sea. The level of risk to maintenance personal is significantly higher. The unpredictable nature of weather and ocean conditions further disrupts planning and operation routines. However wave energy systems designed to be operated on the shoreline are quite immune to the uncertainties and difficulties of the open seas. These systems generally operate from the side of jetties, cliffs, or other existing structures. The power produced by such installations may be connected to the utility grid at significantly lesser cost.

[0008] While shoreline installations have an obvious net operational advantage compared to installations in the open sea, development of such systems have remained limited. Shoreline devices are mostly of the oscillating water column, or the overtopping type. Articulating and reciprocating type wave energy systems which operate from the shorelines have also been proposed for installation on existing structures. However finding suitable locations for erection of such installations on the shoreline is difficult. Often, the waves reaching the shore lack the intensity for these installations to be cost effective. In other cases, the topology of the coastlines may not be very accommodating, excessively inflating the cost of related civil infrastructures for such installations.

[0009] Development and exploitation of wave energy systems for installation in the open water close to the shore is probably an important beginning stage before the wave energy industry is bold enough to venture out in the open sea. However many wave energy devices designed for use near the shore have similar shortcomings as wave energy systems that operate in the open sea. The shallow water near the coast remains as dangerous as the open sea. While arguably most shoreline devices may be operated from dedicated structures constructed in the open sea close to the shore, such arrangements may not be the most cost effective.

[0010] The need for a cost effective wave energy device which can be operated near the coast, and in waves which may not be the most intense, is a first step leading to commercialisation of wave energy in the future. But such devices must have similar operational advantages to shoreline installations in order to attract potential wave energy developers. OBJECTS OF THE INVENTION

[0011] The main object of the invention is to provide for a wave energy harnessing system for operation primarily in open water near the shore, but with comparable advantages to wave energy installations constructed directly on the shore, regarding safety of equipment in harsh weather condition, safety of personal during operation, and ease of connection to the power grid.

[0012] Another objective of the invention is to provide for a wave energy harnessing device with a low mechanical and mass inertia so as to ensure higher power extraction from the waves.

[0013] Another object of the invention is to provide for a wave energy harnessing device where the shock load from intense waves on the power take-off is moderated by a iviiduie iiieai is.

[0014] Another object of the invention is to provide for a wave energy harnessing device for use in shallow water which is secured to the seafloor by a practical, reliable and cost effective method.

[0015] Another object of the invention is to provide for a wave harnessing energy device with a low draft so as to enable wave energy extraction in shallow water.

[0016] Another object of the invention is to provide for a cost effective mechanical drive for the power take-off in articulating wave harnessing devices.

[0017] SUMMARY OF THE INVENTION

[0018] In this present invention, several embodiments of wave energy systems and related components are disclosed. Herein, wave energy harnessing devices are generally referred as wave energy collectors. The most prominent features will be discussed briefly in this summary, without limiting the scope of the invention as expressed by the detail description, drawings and claims that follows.

[0019] In accordance with one embodiments of the invention a wave energy harnessing device is disclosed comprising of a support mast extending above the surface of water which is firmly secured on a pile foundation, and a power extraction system mounted on the mast. During normal operation the power extraction system is lowered in the water down the mast so as to interact with the waves and extract energy. When the waves are too intense for safe operation, the power extraction system is raised up the mast and stationed safely out of water.

[0020] In one aspect of the invention the power extraction system is buoyant. Power is extracted from the waves owing to the pitching movements of hydrodynamic components mounted on the power extraction system, while the power extraction system is able to heave and move freely along the mast during interaction with the waves.

[0021] In another aspect of the invention the power extraction system is moved and secured at specific selected positions on the mast, when energy is extracted from the waves. The power extraction system is displaced as and when required on the mast in order to adapt to tides variation, for the purpose of modulating the power extracted from the waves, or in order to be stationed on top of the mast.

[0022] Another aspect of the invention is that the power extraction system is able to absorb wave surges safely by moving along the mast.

[0023] Another aspect of the invention is the use of water ballast mounted above the waterline of the power extraction system, as a means to limit and modulate power extraction from the waves.

[0024] In accordance with embodiment of the invention a direct mechanical drive system is disclosed for use in power take-off of wave energy harnessing devices comprising of articulating bodies. The mechanical drive system converts high torque slow articulating movement into low torque high rotation cost effectively, as it allows the use of conventional rotary generator without the need of multiple stages of transmission,

[0025] In accordance with embodiments of the invention a method for near coast installation is disclosed so as to minimise underwater construction and to allow safe accesses to the installation for the purpose of maintenance and trouble shooting.

[0026] The embodiments of the invention is preferably for use in shallow water near the coast on monopile foundation, and may be adapted for installation on any other existing structures near the coast or offshore, such as wavebreakers, jetties, mast of offshore wind energy systems. Embodiments of the invention can be also adapted for use on floating supports in deep water installations.

[0027] The features, functions, and advantages in various embodiments of the present invention, can be achieved independently or may be combined in yet other embodiments.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is described with reference to the following drawings:

[0030] FIG. 1 is an isometric view of a wave energy collector comprising of a single monopile mounting arrangement.

[0031] FIG. 2 is a schematic view of the power extraction system and main components inside the mechanical compartment seen from the front.

[0032] FIG. 3 is a schematic view of the power exfraction system and main components inside the mechanical compartment seen from the side.

[0033] FIG. 4 is a side view of the power extraction system in a pitched position due the arriving wavefront.

[0034] FIG. 5 is a side view of the power extraction system in another pitched position due to the advancing wavefront.

[0035] FIG. 6 is a schematic representation of several interconnected wave energy collectors near the shore, with the power extraction system in a raised position when Jiey aie Hut iii OueiauOii.

[0036] FIG. 7 is a schematic representation of several interconnected wave energy collectors near the shore in operation, with the power extraction system in a lowered position interacting with the waves.

[0037] FIG. 8 is a top view of a wave energy farm installation near the coast comprising of a plurality of wave energy collectors. DETAILED DESCRIPTION OF THE INVENTION

[0038] The proposed invention has several embodiments and aspects which are set forth in the detail description that follows. Accompanying drawings are in reference to a preferred embodiment of the invention. The drawings are illustrations only and do not represent full construction details. The proposed invention refers to a Wave energy harnessing device which may be also referred by other names, such as Wave Energy Devices or Wave Energy Collectors. In the description that follows the term “Wave Energy Collector” is used mostly, and abbreviated as WEC.

[0039] An embodiment of the invention is shown in FIG. I.The WEC 20 comprises of a nacelle 21 and a supporting mast 22. The mast 22 is generally vertical and extent substantially above the water surface 23. One of the functions of the mast 22 is to provide a fix support frame for operation of the power take-off (PTO) mounted within the nacelle 21. The mast 22 is generally firmly secured to a marine foundation such as a monopile 24 inserted in the seabed 25. In preferred embodiments of the invention the monopile 24 used as foundation, may extend significantly above the water surface 23 so as to also provide the function of the mast 22, such arrangement being cost effective. In other embodiments of the invention various other supporting means for the nacelle 21 may be considered. Such means may comprise of existing structures in the open sea, for example wave breakers, foundations of offshore wind turbines, or rigs. Similarly in other embodiments, the mast 22 may be also secured to costal structures by appropriate support means.

[0040] In other embodiments of the invention the nacelle 21 may not be buoyant and may need to be mechanically secured to the mast 22 so as to be maintained on the water surface 23. But in preferred embodiments as shown in FIG. 1, the nacelle 21 is completely buoyant and is free to move up and down on the mast 22 during interaction with the waves and to adapt to changing tides. The contact surfaces between the nacelle 21 and the mast 22 is designed so as to minimise frictional resistance to movement, and may preferably comprise of rolling contacts, such as wheels and rollers of various size. These rolling contact devices may be located preferably on the nacelle 21, or on the mast 22. Alternative designs may comprise of frictionless sliding contacts rather than rolling contacts. The embodiment of the invention shown in FIG. 1, make use of a trolley 26 which couple the nacelle 21 to the mast 22. The trolley 26 which is mounted on a plurality of wheels, rollers or guide shoes, is able to travel with little resistance along the mast 22. Guide rails 27 or special reinforce tracks may be provided on the mast 22 in order to prevent premature tear and wear of the mast 22. The upper and lower part of the trolley 26 in contact with the mast 22 are spaced sufficiently apart, so as to prevent excessive forces and torques acting at those point of contacts during normal operation. It is understood that while the trolley 26 is represented as a separate component in the embodiment shown in FIG. 1, in other embodiment of the invention the design and function of trolley 26 may be incorporated within the nacelle 21.

[0041] The trolley 26 shown in FIG. 1 is designed such that the mast 22 is positioned about the center of the nacelle 21. In other embodiments of the WEC 20, the trolley 26 may be designed such that the mast 22 is coupled to the nacelle 21 from the front, rear or lateral sides. In yet other embodiments of the invention the nacelle 21 may be mounted on a plurality of masts 22 for increased structural integrity of the installation. In these alternative embodiments the design of the trolley 26 would vary accordingly.

[0042] Articulating elements of the nacelle 21 interacts with the incoming waves in order to extract wave energy. The articulating element comprises of at least one rigid platform 28 which is rotatably mounted about a pivot 29 firmly secured to the trolley 26. Preferably bearings within the bearing hubs 30 are used to couple the platform 28 to the pivot 29. FIG. 1 shows an illustration of the platform 28. The axis of the pivot 29 is positioned perpendicular to the direction of the waves for optimum extraction of wave energy. In the embodiment as shown in FIG. 1, the pivot 29 extents symmetrically on either side of the trolley 26, given that the nacelle 21 is centrally mounted relative to the mast 22.

[0043] The platform 28 is a rigid construction preferably made of structural steel beams or tubes, and adequately protected from corrosion. The platform 28 may comprise of additional structural traverses and beams for increased strength to withstand occasional shock loads from the waves. The platform 28 may be of other design and made of other materials such as wood, or fibreglass, or others. The pivot 29 generally comprises of a shaft or a horizontal beam which is firmly secured to the trolley 26. In the embodiment shown in FIG. 1 the pivot 29 comprises of two horizontal lateral segments firmly secured to either side of the trolley 26, both aligned with the axis of the mast 22. In alternative design of the nacelle 21 the pivot 29 may not necessarily be aligned with the vertical axis of the mast 22, but rather offset so that it may comprise of a single continuous segment secured to the front or rear side of the trolley 26.

[0044] Buoyant components secured to the platform 28 enable the nacelle 21 to float on the water surface 23 and also enable the platform 28 to articulate about the pivot 29. The buoyant components preferably comprise of floats or buoys of elongated shaped and is referred as terminators 31 in the description. The terminators 31 are secured firmly at the extreme front and rear of the platform 28, so as to generate maximum torque during articulation of the platform 28 about the pivot 29. Respective components of the power take-off (PTO) which are mechanically connected to the trolley 26 and the platform 28 are hence able to operate resulting in extraction of energy from waves during the articulating movements. The power take-off (PTO) is housed within the mechanical compartment 32.

[0045] In other embodiments of the invention the terminators 31 may not be buoyant, but rather designed to react to the surge of the waves. In such embodiment of the invention the nacelle 21 is maintained on the water surface 23 by securing the trolley 26 on the mast 22 at the required height by some locking mechanism. Alternatively buoyant material of required dimensions may be secured to the lower side of the trolley 21.

[0046] The terminators 31 together with the platform 28 and any other equipment mounted on the platform 28 are preferably designed as light as may be possible so as to minimise rotational inertia of the articulating mechanisms. This allows the WEC 20 to couple and react more quickly to the waves, resulting in improved power extraction capacity. The buoyant components of the terminators 31 are generally secured to the lower side of the platform 28 so that critical components of the nacelle 21, such as the bearing hubs 30 or the mechanical compartment 32 are maintained clear above the waterline, reducing contact with corrosive sea water. In preferred embodiments of the WEC 20 where the nacelle 21 is buoyant, the trolley 26 would move freely to the required position on the mast 22 for optimum operation. The need of an adaptation mechanism would be required in embodiments where the trolley 26 remains latched to the mast 22.

[0047] In preferred embodiments of the invention wave energy is extracted as the result of the articulating movements of the platform 28, not the heaving movements of the nacelle 21 about the mast 22. By allowing the nacelle 21 to heave freely during operation excess energy from waves may be diverted safely and smoothly away from the PTO as the nacelle 21 moves upward along the mast 22. This also greatly reduces the induced forces on the whole structure of the WEC 20, the mast 22 and the foundation. The excess energy which is temporarily stored as potential energy in the nacelle 21 is then safely discharged or partially reabsorbed by the PTO as the nacelle 21 returns downward along the mast 22. The excess energy is easily diverted into displacing the nacelle 21 anytime the power extraction of the PTO is reduced or stop completely. In embodiments of the invention where the nacelle 21 is latched to the mast 22 during normal operation, the nacelle 21 may then need to be unlatched at the instance of wave surges harmful to the PTO.

[0048] The forces needed to operate the PTO in the mechanical compartment 32 are provided by the buoyant forces acting on the terminators 31, the weight of the nacelle 21, and the counterforces provided by the mast 22 together with the foundation or monopile 24. As the structural weight of the nacelle 21 may not be sufficient for operation of the PTO at full capacity, addition weight may be required and is provided by ballast 33. The ballast 33 is preferably positioned on the trolley 26 rather than on the platform 28 so as not to increase the rotational inertia of the articulating element of the nacelle 21, which are the platform 28 and the terminators 31. The mass center of the nacelle 21 together with the ballast 33 is generally aligned with the longitudinal axis of the mast 22. The weight and the buoyant forces of the terminators 31 are also laterally balanced about the mast 22.

[0049] The ballast 33 may comprise of concrete blocks. But preferably the ballast 33 would comprise of water tanks as the power extraction capacity of the PTO may be modulated by changing the amount of water in the ballast 33. A further advantage with water filled ballast 33 is that it can be completely emptied before the nacelle 21 is raised to the top of the mast 22, when not in operation. A means to fill and empty the ballast 33 may be provided by a pump system 34 preferably mounted to the lower side of the trolley 26. The pump system 34 would comprise of intake and drain pipes with control valves as required.

[0050] In the embodiment of the invention as shown in FIG. 1, both the terminators 31 comprises of identical cylindrical buoys secured to the platform 28 at equal distance from the pivot 29. But in other embodiment of the WEC 20 the terminators 31 may be spherical or of some other shape. Cylindrical buoys are most suitable to operate in unidirectional waves as more energy is collected by the increased length of the buoys and then transmitted to a single PTO. The use of cylindrical buoys further enable the draft of the nacelle 21 to be reduced significantly in order to operate in shallower water. For a given amount of buoyancy required for a desired power extraction capacity, the draft of the terminators 31 can be significantly reduced by increasing the length. The WEC 20 may hence be designed to operate nearer the shore for a higher power extraction capacity. The terminators 31 may be air filled constructed of metal, fibreglass, or soft flexible material. The terminators 31 may be constructed completely of lightweight material such as foams.

[0051] In other embodiments of the WEC 20 the terminators 31 may not be identical in shape or positioned at equal distance from the pivot 29. Embodiments of the WEC 20 may comprise of a single terminator 31. In yet other embodiments, the trolley 26 may comprise of a plurality of pivots 29 coupled to a plurality of PTOs and terminators 31. In yet other embodiments of the invention one or more of the terminators 31 may not be buoyant, but comprising of surfaces designed to react to the surge components of the waves. The terminators 31 may be designed to be buoyant and to react to the surge component of the waves at the same time.

[0052] In the embodiment of the invention, as shown in FIG. 1 the mechanical compartment 32 is positioned asymmetrically on the platform 28, given that the mast 22 is centered about the platform 28. The resulting unbalanced forces on the pivot 29 and weight distribution on the nacelle 21 need to be properly addressed by careful design. Counterweight may need to be mounted on the opposite lateral side of the platform 28, in addition to the pumping system 34. In alternative designs, as a mean to balance the lateral weight and forces two separate sets of PTOs may be mounted, each located on either side of the mast 22 in separate mechanical compartments 32.

[0053] It is understood that various other designs and mounting arrangements for the articulating mechanism for the PTO may be allowed. The PTOs for use in wave energy systems are generally designed to convert wave energy into useful mechanical energy or electrical energy. Mechanical energy collected from WECs may be used directly to drive pumps in desalination systems. Mechanical energy from a plurality of WECs 20 may be collected in the form of compressed fluids and then transmitted to operate a centralised electrical power generating system. In the preferred embodiment of the invention wave energy is converted directly into electricity on board individual WECs 20 before being transmitted by power cable.

[0054] Wave energy is generally converted into electrical energy after undergoing several stages of conversion depending on the design of the PTO. PTOs may comprise of various hydraulic, pneumatic, mechanical transmission system, or a combination of these systems. More efficient PTOs generally comprise of direct mechanical or direct electrical drive system. In direct mechanical drive systems, a mechanical transmission such as a gearbox with a high gear ratio is used to convert the slow articulating movement of the PTO into higher speed low torque rotation suitable for the generator. As an alternative to gearbox transmission, chain, belt or rope transmissions may be used. While such mechanical transmissions may be less efficient than gear transmission, they may be cost effective depending on the scale and size of the installation. In direct electric drive system the use of a gearbox is avoided and the articulating mechanism of the PTO is coupled directly to linear generators or very low speed rotary generators. Embodiments of the invention may comprise of any of the above type of PTOs.

[0055] In the preferred embodiment of the invention the PTO comprises of a gearbox with meshing gears in a single stage arrangement mounted in the mechanical compartment 32. The design of the proposed PTO is shown in FIG. 2 and FIG. 3. The proposed design is a better compromise between cost and efficiency, as a single stage of gear transmission mechanism is used to transform the slow motion high torque articulations into high speed low torque movements in the range most suitable for commercially available rotary generators. As shown in FIG. 2 and 3, the PTO comprises of a transmission shaft 41 mounted parallel but off-set by significant distance from the pivot 29. The transmission shaft 41 is maintained in position by at least one support arm 42. The transmission shaft 41 is also preferably positioned vertically above the pivot 29 so that the platform 28 is able to pitch equally about the pivot 29 on either side. The transmission shaft 41 is mounted to the support arm 42 on bearings so as to allow rotation with minimum mechanical resistance. The other end of the support arm 42 is firmly secured to pivot 29. While one end of the transmission shaft 41 is secured to a pinion 43, the other end is coupled to a rotary generator 44. In other arrangements the transmission shaft 41 may be connected to additional stages of transmission or gearbox if so required before being coupled to the generator 44. Additional stages of transmission may comprise of a variable type gearbox so that the PTO can operate for a wider range of wave characteristics. Adequate means to lubricate the gears should be provided.

[0056] The pinion 43 is accurately meshed with a curved rack 45 which is firmly secured to the structure of the mechanical compartment 32 by a number of studs 46. The rack 45 would normally extend symmetrically on either side of the pinion 43 when the platform 28 is in a horizontal position, as shown in FIG. 3. The length of the rack 45 is chosen so as to allow the pinion 43 to remain in contact for the maximum inclination of the platform 28 can reach during operation on either side, as shown in FIG. 4 and 5 The maximum inclination of the platform 28 is limited by the allowable spaced for equipments such as the generator 44 within the mechanical compartment 32. Bumpers may need to be provided within the mechanical compartment 32 or on the platform 28 in order to limit the maximum inclination, which generally may not exceed 60 degrees from the horizontal plane on either side.

[0057] The pitching movement of the platform 28 causes the pinion 43 to rotate at a high rotation speed determined by the number of teeth on the pinion 43 and the rack 45. The longer the support arm 42, the lower are the forces acting on the messing teeth of the gears which may hence be designed smaller. The longer the support arm 42, also the larger is the rack 45 and higher is the number of teeth than can be accommodated. These design attributes together contribute in the construction of a cost effective gear mechanism with a high transmission ratio. The length of the support arm 42 and the size of the rack 45, both located above the platform 28, can be easily increased without much constraint. The proposed PTO may be adapted for different embodiments of the invention or any other WECs comprising of articulating components which harness wave energy. While the proposed PTO is described as housed in an enclosure above the waterline, in other adaptation of the design the PTO may be mounted within submerged enclosures.

[0058] The rotary generator 44 may be of the direct or alternating type. The generator 44 may comprise of permanent magnets or field windings which may be varied according to the rotating speed of the transmission shaft 41, for higher power extraction. Various control strategies such as reactive control or latching control may be also implemented to increase the power harnessing capacity of the PTO. In the PTO shown in FIG. 2 and 3, the generator 44 is coupled to the transmission shaft 41 where the direction of rotation changes constantly. Hence the changing polarity of the supply from the generator 44 may need to be rectified, before further power conversion stages given the wide fluctuation in intensity and frequency.

[0059] Mechanical means to protect the generator 44 from over speed or under speed are generally required. A clutch 47 may be included in order to allow the generator 44 to be uncoupled from the transmission shaft 41. A brake 48 mounted on the transmission shaft 41 may be also include in order to slow or stop file rotation of the generator 44. Because of the ability of the nacelle 21 to absorb wave energy by moving up the mast 22, the use of the brake 48 may be an effective way to prevent over speeding of the generator 44 during a power surge caused by sudden intense waves.

[0060] The WEC 20 is generally designed for use near the coast where the waves are naturally aligned by the topology of the shoreline. The WEC 20 may be hence permanently aligned so that the longitudinal axis of the terminators 31 is perpendicular to the direction of the incoming waves. The pitching angle of the platform 28 is also maximised by selection the most appropriate distance between the two terminators 31 which is usually equal or less than half the wavelength of the waves reaching the WEC 20. In such cases as shown in FIG. 4 and 5, when one of the terminators 31 passes through the crest of the waves, the other terminator 31 passes in the trough of the waves. But such ideal conditions are not permanent. Generally the wavelength of waves may vary about a minimum and maximum value, and a mean optimum distance between the terminators 31 is chosen following survey of the specific installation site.

[0061] When the WEC 20 is installed in the open sea where the direction of the waves may change occasionally, then a means to align the orientation of the platform 28 is required. This can be achieved by rotating the guide rails 27 about the mast 22 until the platform 28 is proper aligned in relation to the incoming waves. To facilitate such operation a turntable mechanism with appropriate blocking devices may need to be provided in the mounting arrangement of the guide rail 27 to the mast 22. In yet other embodiments of the WEC 20 where guide rails 27 are not used, the nacelle 21 may be rotated about the trolley 26 by a different arrangement of the turntable mechanism. The turntables may be adjusted manually, or operated remotely or by some automated means.

[0062] Power converters are used to convert the fluctuating supply from the generator 44 into AC supply of constant voltage and frequency, or DC supply of constant voltage rating, according to power transmission requirement. The power convertors would preferably comprise of electronic devices such as rectifiers, voltages boosters, inverters, but may also comprise of electro-machines. The power conversion system may also include temporary energy storage system, such as capacitors and batteries. Transformers for boosting the power output from the power converters to higher transmission voltage may need be also included if the transmission distance is significant. Various monitoring and control systems necessary to operate such installation would be included.

[0063] In the embodiment of the WEC 20 shown in FIG. 1 the power converters are located in the electrical compartment 62 at the top of the mast 22, mainly because access to the WEC 20 is by a ropeway 63. Other embodiments of the invention may not comprise of ropeways 63 and access is by watercrafts. In such cases the electrical compartment 62 may be preferably mounted adjacent the mechanical compartment 32, or the equipments accommodated within.

[0064] When the electrical compartment 62 is located at the top of the mast 22 as shown in FIG. 1, an electrical cable 64 passing though a waterproof access along the pivot 29 connects the generator 44 to the trailing cable 65. A connection box 66 may be provided on the side of the trolley 26 from where the trailing cable 65 and other control cables could be routed to the electrical comportment 62. The trailing cable 65 would usually comprise of multiple conductors so as to power the pumping systems 34, and any other electrical systems on the nacelle 21. Other alternative to the trailing cable 65 may be considered to connect the moving parts of the WEC 20, and such may comprise of travelling cables, spiral cables or cable on reel. The trailing cable 65 would be preferably maintained above the waterline, and is of adequateengin so attow aisptacemem or me nacene zi aiong me run extent or me mast zz.

[0065] A shown in FIG. 1, power is transmitted from the electrical compartment 62 to the power network by aerial power cable 67. In smaller installations the aerial cable 67 may be connected directly to the user when used as an off-grid power source, or to the local grid. The use of aerial power cable 67 is more economical compared to underwater power cable. In typical installations as shown in FIG 6, 7 and 8 the aerial cable 67 may connect a plurality of WECs 20 to a substation 68 before transmitted to the utility grid 69. The aerial power cable 67 may comprise of insulated or bare aluminium cables. Step-up and booster transformers may be mounted on top of the mast 22 for power transmission over significant distance.

[0066] The use of ropeways 63 secured between the masts 22 of the WECs 20 and the substation 68, as shown in FIG 6 and 7, facilitate safe access to the installations any time for maintenance or trouble shooting works, even in poor weather condition. The WEC 20 may further comprise of ladders, safety platforms barriers, and safety nets to enhance safe working condition. The electric compartment 62 being at the top of the mast 22, and the ability to raise the nacelle 21 out of water as shown in FIG. 6, eliminated the need of watercrafts. The ability to reliably carry out routine and scheduled maintenance significantly reduces cost of operation and maintenance.

[0067] The ropeways 63 may comprise of elaborate rope bridge or a simple tyrolean traverse mounted between the masts 22. Aerial cable 67 which are insulated may be secured directly to the ropeways 63. The ropeways 63 and the aerial cable 67 would be generally installed above the water surface at a reasonable height so as not to interfere with the passage of watercrafts or disturb marine activities.

[0068] Ropeways 63 and aerial cables 67 are significant contributing factors in reducing cost of operation. But in installations located far from the shore underwater cables may be required for transmission of electrical power to land and access for personnel may be possible only by watercraft. However such installations comprising of WECs 20 retain many advantages, as has been described.

[0069] The ability of the nacelle 21 to be able to moved up or down the mast 22 on command, is a very important aspect of the invention as has been explained. This principally prevents the main components of the WEC 20 to be exposed to the destructive forces of the intense wave during storm condition. It is understood that the wind loading of the installation during storm condition with the nacelle 21 parked at the top of the mast 22 need to be taken into consideration during design.

[0070] As shown in FIG. 1 , an electrical hoist 71 is used to displace the nacelle 21 up and down the mast 22. The hoist 71 would move the nacelle 21 up by pulling on the wire rope 72 firmly attached to the structure of the nacelle 21. To move the nacelle 21 downward, the hoist 71 would release the wire rope 72 gradually. The wire rope 72 needs a reasonable amount of slack so as not to interfere or limit the natural heaving movement of the nacelle 21 during operation. When the nacelle 21 is safely parked at the top of the mast 22, it may be further secure to the mast 22 as a precaution against breakage of the wire rope 72.

[0071] The power to operate the electric hoist 71 is preferably tapped from the aerial power cable 67 which are generally permanently energised, or from an auxiliary power supply such as a battery within the electric compartment 62. Such an auxiliary power may be essential in off-grid installation where the power in the aerial cable 67 may become interrupted once the nacelle 21 is removed from the sea and the PTO is not generating energy.

[0072] In some other embodiments of the invention the electrical hoist 71 may have additional use. The electric hoist 71 may be used as a way to modulate the power extraction of the PTO by partially raising the nacelle 21 from the ocean and reducing it interactions with the waves. In some other embodiment of the invention the electric hoist 71 can be also used as a generator harnessing wave energy from the heaving movement of the nacelle 21. In these embodiments the wire rope 72 is maintained permanently under tension so that during the downward movement of the nacelle 21, the motor of the electric hoist 71 in able to rotate in generator mode. The energy harnessed by the electric hoist 71 would be processed and injected to the aerial cable 67. The advantage of monopiles as foundation, over other any other types of marine foundation to support the mast 22 is obviously the cost, and the relative ease to install monopiles and piles in the seabed 25. Erection of piles of reasonable size in near coast environment is quite a routine operation, and such work can be carried out easily by most civil contractors. While the use of a single monopile 24 is preferred, the foundation for the mast 22 may also comprise of several monopile 24 linked by a common beams, where the beams could then be used to support a plurality of masts 22. In preferred embodiment of the invention the mast 22 is also part of the same monopile 24 foundation which extends above the water surface 23.

[0073] The foundation and the mast 22 is designed to support the total weight of the installation and the various forces acting on the installation due to operation of the PTO.and the forces due to waves and winds acting on the structure in intense condition. Various construction materials such as concrete, steel pipe and structural bars may be used for erection of the mast 22 and the monopile 24. Steel structures need to be protected from the corrosive sea water by suitable means. The use of wood as mast 22 and monopile 24 may be most ecological compared to other construction material, and may be widely use for installation of smaller capacity.

[0074] The proposed WEC 20 is most suitable for installation in shallow water near the shore as shown in FIG. 6, as the foundation may be erected cost effectively and the use of convention aerial power cables 67. Close to the shore where the waves are not intense the WECs 20 may be designed to generate power in the range of 5 to 20 KW. At some locations near the shore where the waves are more intense a single WEC 20 may be able to generate energy in the range of hundred kilowatts.

[0075] Wave energy farms as shown in FIG. 8, comprising of many interconnected small capacity WECs 20 close to one another, and connected by ropeways 63 and aerial power cables 67 may have a combined power capacity of several hundreds of kilowatts or megawatt of energy. These installations may be cost effectively constructed and operated near the coast. The plurality of WECs 20 may be spread over a large area near the coast, and interconnected at high transmission voltage according to practice and methods widely used for long distance power transmission. Such installation may comprise of large numbers of WECs 20 along the shoreline over long distances. Such installations may have little or no environmental impact to the marine life because of low footprint, and because of the absence of dangerous moving parts. The WECs 20 when installed very close to each other in large numbers may perform as an effective wavebreaker, mitigating or preventing coastal erosion.

[0076] In some installations as shown in FIG. 8, the plurality of WECs 20 may be installed in compact arrangement with several rows aligned in the direction of the wavefronts 74. In such cases the structural integrity of the whole installation may be further reinforced by the use of aerial structural 75 linking the top of all the masts 22. The aerial structures 75 may comprise of solid links or wire rope. The masts 22 may be further reinforced by the use of guy wires 76 anchored to the seabed 25 or on land 73 or any other structures. The aerial structural 75 and guy wires 76 would be used to support the ropeways 63 and the aerial cables 67 between the WECs 20.

[0077] The WECs 20 may be also installed offshore in depth where erection of monopile foundations is cost effective. Where the seawater is too deep for erection of foundations to the seabed 25 the mast 22 may be erected above the water surface 23 by the used of floating base and counterweights which are secured to the seabed 25 by moorings, very similar to offshore mast of wind turbines. The WEC 20 with some adaptations may also be mounted to existing offshore structures, such as rigs and mast of the wind turbines. Similarly WECs 20 may be adapted to onshore structures such as the side of jetties or seawalls.

[0078] The use of the proposed WEC 20 is most practical for remote communities along the coast or for personal use, as it requires few human supervision and intervention. Sensors monitoring the wave condition would automatically signal the WEC 20 when to move the nacelle 21 down the mast 22, or when to stop operating and move to the top of the mast 22. The absence of moorings to secure the installation in the sea greatly simplifies exploitation. Moorings used in floating type wave energy systems may be subjected to breakage and need to be regularly inspected. The mast 22 may also conveniently accommodate wind turbines and solar panels. The wind turbine may be preferably of the vertical axial type as this allows the masts 22 to be installed close to each other in energy farms.

[0079] Embodiments of the invention may have different structures and shapes, without departing from the scope of the invention. The invention has been described with reference to a certain embodiments thereof, but numerous other variations are possible. Embodiments of the invention are also not intended to be limited by the drawings herein, but may be carried with other choice of designs, and methods of construction. The invention may have embodiments within a form which does not provide all the features and benefits set forth, as some of the features may be used or practice separately from others. It should be understood that various omission, substitution, and changes in design may be made without departing from the spirit of the invention. The invention is also not limited by choice of construction material. Embodiments of the invention may be constructed with material most suitable to the particular size of the embodiments and the condition of operation. The scope of the invention is also indicated by the foregoing descriptions and the appended claims.

Claims

AMENDED CLAIMS received by the International Bureau on 10 September 2025 (10.09.2025)The embodiments of the inventions in which an exclusive property or privilege is claimed are as follows:

1. A wave energy harnessing device comprising: at least one support structure maintained secured and relatively stationary to incoming waves; a support component mounted to said support structure wherein said support component is able to move on said support structure between a lower and an upper position; at least one buoyant body pivotally mounted about a horizontal axis to said support component so as to allow said buoyant body to pitch from side to side during interacting with waves; a least one power extraction system operated by the relative movement of said buoyant body; and at least one weight ballast mounted on said support component in order to provide torque for the operation of said power extraction system;2. A wave energy harnessing device as in claim 1, wherein said weight ballast comprises of water ballast mounted above the waterline.

3. A wave energy harnessing device as in claim 1 , wherein said support structure extends substantially above the water surface of the ocean, so as to allow said buoyant body to be completely raised above the waterline when said support component is stationed at the extreme upper position on said support structure.

4. A wave energy harnessing device as in claim 3, wherein said support structure is generally vertical and firmly secured to the seabed.

5. A wave energy harnessing device as in claim 4, wherein said support structure comprises of at least one monopile firmly secured to the seabed.

6. A wave energy device according to claim 1 , comprising of a means to move said support component on said support structure.

7. A wave energy harnessing device as in claim 1 , comprising a means to position said buoyant body relative to the incoming waves for optimum energy extraction.

8. A wave energy harnessing device as in claim 1 , wherein said power extraction power extraction system comprises of: at least a driveshaft rotatably mounted to said support structure, wherein saiddriveshaft is parallel and off-set from said buoyant body pitching axis; at least one transmission mechanism wherein said transmission mechanism with higher rotation shaft is coupled to said driveshaft; wherein said transmission mechanism with lower rotation shaft is coupled to said buoyant body such that movement of said buoyant body about it supporting axis causes said driveshaft to rotate; and a generator coupled to said driveshaft.

9. A wave energy device according to claim 1 comprising of an aerial bridge secured to said support structure, so as to allow safe access for maintenance personnel.

10. A wave energy device according to claim 1 comprising of aerial power cable mounted on said support structure for power transmission to a power grid.[0001][0002]STATEMENT UNDER ARTICLE 19 (1)[0003]Application: PCT / CA2025 / 00001[0004]International filing date: 7thApril 2025[0005]Mailing date of International Search Report : 25thJuly 2025[0006]Mailing date of response: 22ndAugust 2025[0007]The proposed device is very different from the device in DI. The propose device is a floating type device that operate from a fixed frame (which mainly comprise of a pile extending well above the waterline) and with all the interacting components located above the waterline. The device in DI is a floating type device where most of the interacting components are submerge below the waterline.[0008]In the proposed device the pile is an essential component which provides a fixed frame for the Power Take Off system. The pile also enables the operating part of the device to be raised far from above the water line during severe sea condition. The pile also provides support for power lines and aerial bridge, contributing in a significant manner to lower construction, operation and maintenance cost.[0009]The device in DI makes use of a pile as an optional element, as a means to secure the device under water and to provide a fixed frame in combination with some other components. The pile in related embodiments provides a means to position the device relative to the orientation of the waves and the tides. The pile may also provide a means to lower the device underwater . during sever sea condition.[0010]The device in DI makes use of a water ballast which is submerged below the water line, but which serves a very difference purpose from the one in the proposed device. The water ballast as described in claim 28 is basically used as a means to control the buoyancy of the floats, in order to adjust the depth of the floats in water. Apparently alternative means may be provided. There is no indication as to how this feature affects other operation of the device in DI.[0011]The proposed device makes use of a water ballast mounted above the waterline. The ballast is also secured to very specific movable component along the pile, in order to produce a result which is not obvious to a person skill in the art. The force of gravity from the ballast is essential for the operation of the Power Take Off (PTO). For that reason the ballast is located above the waterline. At the same time the ballast together with other connected elements prevent the forces operating the PTO from exceeding dangerous threshold values resulting from occasional rogue waves while in operation, thus allowing continuous operation. The ballast is also used to modulate the desired level of power produce by the PTO.

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