AU2016204694A1 - A floating wave energy conversion system - Google Patents

Abstract

Abstract A wave energy conversion (WEC) system that can be deployed to or retrieved from its 'zone of deployment', that may be in shallow or deep water body 2, as a floating module. The WEC comprises of a floatable and also submersible body 1 with openings in the leading 10 and lagging 12 ends connected by a duct, and a wheel 30 suspended in the midsection 11 of the duct, wherethrough the wave flowing inside the duct rotates the wheel. The WEC operates autonomously and remotely, that could adjust and maintain its submergence relating to the optimal position in harnessing the energy of the horizontally moving wave 3 at the surface of the body of water 2. The external profile of the WEC is formed to create the least drag by wave and wind dynamics, and stayed against the wave direction by means of mooring line 6. D aW ngs LT-1

Description

Title

Floating Wave Energy Conversion System

Field [05] This invention relates to a submersible floating device that is capable of adjusting its submersion in order to optimize the harnessing of wave’s kinetic energy and the subsequent conversion into torsional power. The invention also relates to the energy conversion systems and the methods of ballasting and mooring the devise for the best possible position with regards to the condition of the waves.

[10] The invention has been devised for the conversion of but not limited to the kinetic energy from the horizontal velocity of the wave into torsional power by means of a water turbine or wheel or similar configurations attached to a shaft that rotates in accordance with the horizontal motion of the wave, as the primary energy conversion method. Also attached to the shaft is a flywheel that stores kinetic energy and releases it in the form of centrifugal forces to sustain the rotational inertia in between the wave cycle. Also, another energy conversion is accomplished by means of water pressure augmentation devise that are driven by the shaft, that may be a pump, that pressurizes seawater for storage and for subsequent supply to downstream users.

[15] The invention also relates to the conversion of the stored energy of the pressurized water into other forms through other component device such as but not limited to water turbine, that converts kinetic energy into rotating shaft power.

[20] The invention has been devised to normally operate partially submerged at the water surface with built-in systems for ballasting and self-adjustment of submersion for performance or maintenance optimization or may be fully submerged for reasons of but not limited to adverse weather condition.

Background [05] Among various sources or renewable energy that is available above the earth’s surface, ocean wave has comparatively the highest magnitude of recoverable stored energy per linear measure. It is also the most predictable and prevalent in the majority of the coastal regions of the world. However, the current global contribution of wave energy in the renewable energy mix is close to zero. This is highlighted by the studies done by a number of entities around the globe, demonstrating that wave energy converter (WEC) has the highest net present value of the unit cost per energy generated over its designed service life, also known as the levelized energy cost (LEC), compared to that of solar, wind, hydro and biomass. The main contributor to the high LEC is influenced by the harsh ocean environment where the source of wave energy is abundant, and to the lack of mature, scalable technology to address the challenges of converting this energy into another form that is useful to the needs of our communities or industries.

[10] The potential energy contained in ocean wave is converted into another form by harnessing the work generated by the movement of a body acted upon by the influences of the cyclical movement of the wave that causes the body to heave, surge, pitch, roll, and yaw - in one directional order or combination thereof. Several previous inventions in the literature, utilizes various types of WEC to harness the work done with the wave and to transmit it in a controlled functional source of energy.

[15] A number of previous inventions had attempted to eliminate the effect of adverse weather condition by positioning the WEC fully submerged at sea floor or considerably below the water surface in the case of heaving buoy attached to a pump mounted in the seafloor. In such cases the succeeding installation and maintenance costs is the major factor in the higher LEC. The sluggish advance in the field of wave energy as a promising contributor in the renewable energy mix, is a testament to the many failures of the previous inventions in the harsh reality of the oceans and the unattractive economic rewards due to the high LEC.

[05] It is with these prevailing background that the present invention is designed to address the technological and commercial hindrances to the scalability of WEC device. The present invention is conceived with the intent of mitigating the challenges imposed by the harsh ocean conditions and improve the comparative costs associated with the WEC installation, operation and maintenance.

Summary of the Invention [10] The problems associated with harnessing the energy from wave are compounded by the very environment where the WEC device operates, with the prospect of the abundant presence of naturally occurring waves and where the wave dispersion is predictable. The ostensibly endless forces of wave acting upon the WEC devise presents a formidable challenge in directing it into a net usable power for energy conversion. This includes the considerations for supporting the device either at the water surface or underneath in order for it to function as intended. The saline water elements, marine growth and the increasing external pressure relative to the depth of immersion are detrimental factors to the WEC devise configuration and material of construction. Also, the deployment and retrieval of offshore devise requires greater details and methodologies as compared to an onshore mounted device. This is more pronounced when it involves subsea installed or tethered submerged objects.

[15] The aforementioned factors are contributing to the relatively high costs of construction, installation and maintenance of WEC devise. This problem is the hindrance to the attractiveness of wave energy as a potential major contributor to the renewable energy mix.

[05] The present invention intends to address the aforementioned problems and the difficulties associated with it. It is an object of the present invention to mitigate the unattractiveness of WEC business cases due to high LEC.

[10] The present invention as a WEC system may be operated to optimally harness the greatest wave energy density at the water surface, while configuring its mass cross-section and external profiles to smoothly interface with the surrounding body of water and offshore wind in order to reduce the requirement or mooring supports.

[15] The WEC may be fully submerge to water depth that has a lesser effect of adverse weather, increasing its ability to withstand the extreme conditions of a storm event.

[20] With the present invention, the consequential mode of energy supply upon conversion of wave energy is in the form of pressurized seawater. It can be directed to desalination plant for the continuous potable water supply or hydroturbine generator for the production of electricity.

[25] In coastal areas where ocean wave is observed to have considerable heights year- round, it is envisioned that the present invention will significantly increase the contribution to the renewable energy mix, with the possibility of a 100% renewable source for both local power grid and potable water supply. Also, due to the mobility, scalability and modularity of the present invention, the adaptation of WEC as a major contributor in the renewable energy mix may be greatly enhanced.

Brief Description of Drawings [30] The invention is illustrated in the following drawings with the description of the specific embodiment thereof in which: [05] Figure 1 is a schematic arrangement of the invention, shown floating semisubmerge according to the embodiment, being shown connected to a subsea anchor and an export subsea pipeline.

[10] Figure 2 is a schematic arrangement of the invention, shown floating fully-submerged according to the embodiment.

[15] Figure 3 is a perspective view of the invention incorporating a floating device with corresponding marine enclosure that contains the wave energy conversion components according to the embodiment. The view is showing the front (bow) and right side (starboard) of the device.

[20] Figure 4 is a perspective view showing the back (stern) and left side (portside) of the device.

[25] Figure 5 is a perspective view shown in Figure 3, with the top enclosure according to the embodiment removed to reveal the arrangement of the associated components inside.

[30] Figure 6 is a perspective view shown in Figure 4, with the top enclosure according to the embodiment removed to reveal further arrangement on the left side.

[35] Figure 7 is a plan view of the arrangement shown in Figure 5 and Figure 6.

[40] Figure 8 is an elevational view of the device viewed from the bow.

[45] Figure 9 is a sectional elevational view of the device viewed from the cutting plane A-A as shown in Figure 8.

[50] Figure 10 is a plan view of the device with the arrangement shown in Figure 4, with the enclosure according to the embodiment.

[05] Figure 11 is a sectional elevational view of the device viewed from the cutting plane B-B as shown in Figure 10.

[10] Figure 12 is a plan view of the device with the arrangement shown in Figure 3.

[15] Figure 13 is a sectional elevational view of the device viewed from the cutting plane C-C as shown in Figure 12.

[20] Figure 14 is a sectional elevational view of the device viewed from the cutting plane D-D as shown in Figure 12.

[25] Figure 15 is a bottom view of the arrangement shown in Figure 10.

[30] Figure 16 is a perspective view in the arrangement of Figure 4, with several parts of the embodiment removed to reveal the components of the energy conversion system.

[35] Figure 17 is an elevational left side view of the arrangement in Figure 16.

[40] Figure 18 is a plan view of the arrangement in Figure 16.

Description of the Preferred Embodiments [45] The WEC device 1 is designed to operate on the surface of the body of sea water 2 with the prevalence of wave 3 and where the natural energy of the wave is at optimum. Referring to the drawings, the device 1 is illustrated as an assembly of components comprising a floating wave energy conversion plant. According to the embodiment of the present invention the kinetic energy of the horizontal movement of the wave will be harnessed and converted into useful form, the process of which shall be detailed further in the description. The intended product is exportable pressurized sea water, constantly available for conversion into another form of energy such as electricity or for desalination into potable water, or for co-generation of both electricity and potable water.

[05] As shown in Figure 1 the present invention may be anchored from the subsea bed utilizing at least one chain line 6 connecting the seabed anchor 5 and branching to each of the transom 21 on both sides of the device as mooring system. More than one mooring lines may be utilized, but not more than what can result to hindering the free enablement of the WEC 1 to self-align, with its longitude being perpendicular to the incoming waves. It is not limited to considering various anchoring options available in the offshore industry that is most suitable for the depth of the body of sea water 2 and the local characteristics of the seabed 3. For this illustration purposes a suction pile is considered embedded and made rigid in the seabed, shown as anchor 5.

[10] To optimize the capture of wave energy it is preferred that the present invention will be deployed preferably in water depth before the wave 3 reach its breaking point, otherwise referred in the description as the “zone of deployment ”. The present invention can be configured to go fully submerge as shown in Figure 2, to escape the tremendous and may be damaging waves at the sea surface during severe storm condition. For this purpose the WEC 1 may be submerged up to (but not necessarily) a water depth of approximately one-half of the wavelength, where the load effect of the surface disturbance to both the device and the mooring system is lesser.

[15] In offshore operation the WEC 1 is intended to operate fully automated, unmanned and with remote monitoring of the parameters that are pertinent to its efficient operation and maintenance. With this intent, at least two options for the communication mode are considered possible. The first and preferred option, is by using a wireless communication system and a wireless antenna 92 is installed at the top of mast 90. The wireless antenna is connected to the control components inside the power and control cabinet 81, transmitting data to a monitoring base (that is may be a control room at the export destination), and may be also configured to receive control signal from the said base.

[05] The second and an alternative option is by connecting the WEC 1 to the monitoring base through a communication cable 95 attached to and running along the pressurized water export line 66.

[10] With the Option 1 for communication also shown in Figure 2, to enable continuity of signal or data relay between the monitoring base and the fully submerged device, the antenna 21 can be fitted with a buoy 93 to remain floated at the wave surface 3, and connected to the WEC 1 by a tether and communication cable bundle 94.

[15] However, the present invention can also be designed and built with the basic capability of withstanding the extreme weather scenario specified in the intended zone of deployment, where an absence of seasonal severe storms is prevalent within the considered offshore service span. In this regard, the WEC 1 may not necessarily be built with the fully submerge capability. In such a case, some components of the present invention can be considered optional for lower capital cost, such as; a smaller ballasting tank 101, a smaller high pressure air receiver 73, a smaller air compressor 70, elimination of the communication buoy 93, removal of the tether and communication cable bundle 94 and the redundancy of communication cable 95. With Option 1 being the residual mode of communication. The relevance of these components in the operation of the present invention will be discussed further in the description.

[20] The WEC 1 may be operated in deeper water where subsea or floating facilities such as but not limited to the exploration and production of petroleum and other minerals are existing or planned for installation. That is to supplement the facilities with the necessary utilities such as electricity for surface and subsea controls, compressed air and pressurized sea water for desalination or well drilling operations use. In this case, the anchoring may be incorporated into the fixed platform or floating facilities.

[25] According to the embodiment of the present invention the WEC 1 is a floating body that allows the horizontal wave surge to pass through the duct inlet 10 and exits at duct outlet 12. Midway along the inlet and the outlet duct is wheel housing 11 (illustrated in Figure 7,16,17 and 18) that encloses a wheel 30, supported in-between bearings 32 through a shaft 31, being rotated by the passing surge of the wave. Thus, converting the energy from the wave into shaft work. At least one wheel assembly for this purpose is required, but the number of wheel arrangement and the associated inlet and outlet ducts may be increased in corresponding number or in width according to the intended power to be generated by the WEC 1, that is determined in the detailed design. Further conversion of the energy and the associated components relating to the WEC shall be discussed further in the description.

[05] The external profile of the hull 20, the straight board 23, the topside enclosure 24 and the ballast 100 are streamlined to form the shown curvatures that corresponds to the best hydrodynamic profile for the least drag imposed by the surge of waves and gusts of wind. The external skin of the normally submerge area of the hull 20, the straight board 23 and the ballast 100 may be coated with a layer of suitable material to aid in the reduction of the drag. The same suitable coating may also be applied as retardant to marine growth.

[10] Only the lower half of the wheel 30 inside the lower housing 11 is subjected to the flow of sea water progressing from the horizontal wave movement at inlet 10. While the upper half of the wheel enclosed by the upper housing 14 is vented to the atmosphere through the vent line 15 terminating above the topside 24.

[15] The height 18 of the duct opening at inlet 10 may be determined according to the expected average total height of waves in the zone of deployment. According to the embodiment, the amplitude of wave 3 will be captured as much as possibly accommodated by the height 18 for the optimal harnessing of wave surge energy. While the width 19 of the duct opening will depend on the intended power to be generated by a single wheel. It is estimated that at any given time, there are 10 to 35 kW/m of energy density in ocean wave. However, it is the relative actual positive force of the wave 3 horizontal surge acting on the effective area of the wheel 30 paddles that determines the work transmitted to the shaft 31.

[05] The inlet duct may be converging but not limited to, towards the connection to the wheel housing 11. As illustrated in Figures 7, 16 and 18, where the width of the wheel is lesser than the opening width of the inlet duct. The outlet duct would diverge at least with the same rate as the convergence of the inlet duct, but preferably more to ease the outgoing flow.

[10] The depth of submergence is being monitored by the sensors 22 installed in the lower section of the hull 20. There are at least four sensors, one on each side of the inlet 10 and outlet 12 ducts. The sensors 22 may be sensing the hydrostatic pressure above it and sends data to the control module 81, which is responsible for controlling the amount of reserve buoyancy of the WEC 1.

[15] According to the embodiment of the present invention, the device will be partly submerged so that the crest and trough of the wave 3 will be touching the top 16 and bottom 17 respectively at the duct inlet 10. With the inputs coming from the sensors 22, the control module shall determine the appropriate reserve buoyancy of the WEC 1 and shall consequently actuate either of the high pressure air supply valve 103 or air vent valve 104 to respectively reduce or increase the level of water in the ballast tanks 100, with the objective of floating the device only to the optimal submergence while in operation.

[20] There are three ballast compartments comprising the ballast tanks 100, the bow ballast tank 101, the mid ballast tank 102 and the stern ballast tank 103. Each one is connected to the high pressure air supply for de-ballasting and a venting valve 105 for each is also installed for ballasting. The mid ballast tank 103 is mainly related to the majority of the buoyancy reserve of the device. While the ballast tanks 101 and 104 are respectively, relating to adjusting the pitch inclination of the WEC 1 with respect to the horizontal of wave surface 3. The air supply valve 104 and the air vent valve 105 is closed to hold the required volume of air inside the ballast tank. Both of the valves in a ballast tank may be closed at the same time, but cannot be open at the same time. Once the high pressure air supply valve 103 of the ballast tank 101 is open, the water inside the ballast tank recedes through an opening 106 at the bottom of the tank. Thus, increasing the reserve buoyancy of the device. Once the vent valve 105 is open, the air inside the tank is pushed out and seawater fills the tank through the bottom opening 106. Thus, decreasing the buoyancy reserve and causing the device to increase its submergence.

[05] The WEC 1 is preferably floated with the bow slightly higher than the stern at all time, wherever is the position of the WEC 1 during a long wave cycle, to ensure that the flow of water from the wave is consistently from the duct inlet 10 at the bow and towards the outlet 12 at the stern. This will prevent a counter rotation of the wheel from what is intended, according to the preferred arrangement. The right combination of the ballasting of tank 100 and 103 is intended to accomplish the proper inclination.

[10] The trunnion 21 is located on each side of the device to which the mooring line will be connected with a pivot. The mooring line is preferably chain connected to the anchor 5 at seabed 4 and branching to each of the trunnion pivot connection. The weight of the chain line is intended to stay the WEC 1 with the least relative backwards movement at its floating state against the swell of waves. The design of the original total reserve buoyancy of WEC 1 shall consider the weight of the intended mooring system.

[15] The embodiment of the present invention shall provide a constant flow of pressurized seawater available for internal plant use and for export. The energy conversion process of the wave horizontal movement to the stored pressurized water involve transfers of the energy from one form into another according to the following steps: [20] The moving horizontally wave 3 surges into the inlet duct 10 and flows through the wheel casing 11 and exiting from the WEC 1 at the outlet of the duct 12. The paddles of wheel 30 is being pushed by the flow of seawater, causing the shaft 31 to rotate. Thus, converting the kinetic energy from the wave into a shaft work.

[05] Also fitted into the shaft 31 is at least one flywheel that can be located on either side of the wheel 30, or as shown in Figure 5 as a pair of flywheels 33 with one set on each side. The flywheel 33 rotates with the shaft 31 storing some of the kinetic energy into a potential source to sustain the shaft rotation. The stored energy in the spinning flywheel 33 will enable the shaft 31 to ride-through its rotation during the fluctuation in the flow of seawater through the duct 11.

[10] Another component fitted into one of the shaft end is the bigger sprocket 40 of a chain drive 41, transmitting power from the shaft to the pump 50 through a smaller sprocket 42. The chain drive is preferable for the application due to the expected shock loads brought by the intermittent surging of wave 3.

[15] The weight of the shaft 31, the wheel 30, the flywheels 33 and part of the chain drive at one end of the shaft is being supported by two bearings 32 mounted equidistant from the wheel 10 on both sides.

[20] The driven pump 50 is preferably a reciprocating pump of a duplex type or more plungers, this will ensure the delivery of pressurized water evenly with the expected variable speed nature of the drive. The pump 50 draws low head sea water through the suction line 51 from a suction inlet 53 located at the bottom of the hull 20. The pump discharges a highly pressurized seawater into a hydrophore tank 62, through a high pressure discharge line 60 and a non-return valve 61. At this stage the kinetic energy of the sea wave 3 is converted into a more readily usable stored energy in the form of pressurized sea water.

[25] The hydrophore tank 62 will serve to dampen the variable discharge flow of the pump 50 and will act as a buffer of the high pressure water supply for internal plant use and in greater part for export.

[05] The hydrophore tank 62 is half filled with the pressurized seawater, while the upper half is filled with compressed air pre-set at the hydraulic head required at the termination end of the pressurized sea water export line 66. During wave 3 phase intervals where the pump 50 discharge fluctuates to the low point, the air pressure inside the hydrophore tank 62 will push the water out to ensure an uninterrupted flow of high pressure water to the users and for export. The ratio of the volume of the hydrophore tank 62 and that of the pre-charge air 79 is determined so that discharging at low pump 50 output by an elapsed time of not less than the longest wave cycle observed in the WEC 1 deployment zone, will not totally deplete the hydrophore tank of pressurized seawater.

[10] Compressed air for ballasting and electricity for controls, communication and lightings will be generated for use in the operation of WEC 1, as part of the embodiment of the present invention. This is made possible by the use of an impulse type water turbine 67 that converts the stored energy of the pressurized seawater through the valve 64, released as kinetic energy and converted as shaft work output.

[15] The power from the shaft of the impulse turbine 67 can be transmitted to the air compressor 70 through a coupling 43. Enabling the compressor to store high pressure compressed air into the air receiver 73 through the compressor discharge line 71 and the non-return valve 72.

[20] Similarly, the power from the shaft of an impulse turbine 67 can be transmitted to the alternator 80 for electric power generation. This electricity generated is feed into the power and control cabinet 81 where the power supply is further distributed upon transformation into the required input of the following users: [25] The battery charger 85 uses the electricity for charging the storage battery 83. The storage battery is a back-up power supply only for communication and controls during a fully submerged condition of WEC 1.

[05] The computers inside the power and control cabinet 81 will be powered by electricity for the instrumentation and controls, for data transmission to the land base, for lighting inside the WEC 1 as needed and for navigational signal lights 91.

[10] Electric power is also used for the actuation of all the valves (53, 56, 59, 61,63, 64, 74, 76, 77, 78, 103, 104, 105 and 121) represented in the drawings whether for air or water services. The sequencing and timing of the valve actuations will be fully automated for remote and autonomous operation, with its control module integrated with the power and control cabinet 81, as per the embodiment of the present invention. However, an operation interface from an associated land base plant may be configured for maintenance and safety monitoring as a minimum requirement of the holistic system. This land base plant may be the importer of the pressurized water, such as a desalination or power generation plant or both, or the responsible owner of the WEC 1.

[15] The forced ventilation fan 124 will be powered by electricity whenever an entry inside the WEC 1 is necessary.

[20] The drain pump 131 is motor driven and powered by electricity.

[25] The air compressor 70 draws ambient air through the air suction line 120, passing through the valve 121 and the condensate eliminator 122. The mist eliminator shall drain any trapped liquid through the drain line 123 connecting to the seawater drain line 58 upstream of the drain valve 59.

[30] The air compressor is intended to operate while the WEC 1 is floating on the surface of the body of water 2 or its normal operating mode. It shall maintain a full pressure charge of the air receiver 73. The storage volume capacity of the air receiver 73 is at least commensurate to the air volume required to vacate the ballast tanks 100, 101 and 102 for purposes of bringing the WEC 1 into the surface during and after an event of full submergence. While in full submergence, the air compressor will not be operated and the isolation valve 121 will remain close.

[05] A marine entry hatch 25 is provided for manual entry into the WEC 1 for purposes of periodic maintenance, inspection and any intervention that might be required during the operation of the device. While floating in the zone of deployment, the WEC 1 can be accessed by a suitable marine service boat. An access ladder 110 is provided for transfer of personnel from the boat to the topside 24. A man entry hatches 25 can be opened from the outside, exposing the access tube 112 with an internal tube ladder 113. A watertight entry door 115 is located at the base of the access tubel 12, which can be opened or closed from both sides.

[10] A force ventilation fan 124 is connected to the air suction line 120 with its electric motor automatically operated together with the internal lightings 85 once the door 114 is open. This will ensure that the inside environment of WEC 1 will be suitable for man entry for the performance of tasks.

[15] A drain pit 130 is located at the lowest drain point of the WEC 1 enclosed spaces in the hull 20 and top side 24 including the access tube 112. All sea water that might leak or unintentionally released inside the enclosed space will drain to the drain pit 130. The drain pump 131 is located at the base of the pit and will be automatically actuated to operate at a pre-set level of liquid in the drain pit 130. The discharge of the drain pump 131 is connected to the drain line 58 upstream of the drain valve 59.

Claims (25)

1. The Claims of the Present Invention

   1. A wave energy converter (WEC) operating on the water surface, floating and partially submerge, comprising a body that is hydro-dynamically shaped to allow the smooth passing of wave or wind along the longitudinal submerged and externally exposed surfaces, stationed by at least one mooring line so that it resists the horizontal movement of the wave but self-align longitudinally perpendicular to the vertical plane of the wave.
2. 2. A WEC according to claim 1, wherein a duct with an opening on both ends running longitudinally along the body and co-planar with the wave allowing some of the horizontally moving waves to pass through the duct, entering into the bow opening and out through the stern opening, and a wheel or rotor or similar configuration is mounted at midpoint of the duct.
3. 3. A WEC according to claim 1 and 2, wherein the body bounded by the shell of the hull, the topside, the straight board, the wheel enclosures, and the duct boundaries are watertight and generally floated by buoyancy. The volume of the aforementioned body, together with the volume of unfilled ballast tanks, will correspond to the overall volume of displacement to fully submerge.
4. 4. A WEC according to claim 2, wherein the wheel or rotor is comprising a hub and multiple extended paddles, or blades protruding from the hub towards but not touching the boundary of the enclosures and may or may not have side plates supporting the paddles, or blades from the hub, and is free to rotate with its mounting shaft, and with the shaft and the hub located above the upper boundary of the dust cleared from the flow of the wave.
5. 5. A WEC according to claim 3, wherein the wheel or rotor is enclosed by a lower and upper enclosures that are joint watertight with the duct, and the lower paddles, or blades of the wheel or rotor inside the lower enclosure is situated along the flow of the wave through the duct, and the force of the flowing wave is causing the wheel to rotate.
6. 6. A WEC according to claim 2 and claim 4, wherein the duct may be converging from the leading opening to the wheel or rotor lower enclosure and diverging towards the lagging opening, or the duct is homogenous in cross-section from one opening to the other.
7. 7. A WEC according to the claims above, wherein there are multiple ducts arranged in parallel in a single float intended for simultaneous or for some standby or redundant configuration of the wave energy conversion.
8. 8. A WEC according to claim 1 and claim 2, wherein the submergence is controlled by ballasting so that the crest of the wave is intended to be conterminous with the upper boundary of the bow opening of the duct, and the body ballasted with inclination so that the bow end is slightly higher than the stern end at all time.
9. 9. A WEC according to claim 8, wherein the ballasting is dynamic and accomplished by the introduction of compressed air and thereby the displacement of seawater in at least one or multiple ballast tanks.
10. 10. A WEC according to claim 8 and 9, wherein the ballasting is automatically controlled by an on-board computerized control system with electro-mechanical or electro-pneumatic components relating to the instrumentation, control, data transmission and the autonomous operations of the WEC.
11. 11. A WEC according to claim 10, wherein the sensors are mounted on the submerge section of the hull, both at the leading and lagging end and on both longitudinal sides, intended to measure the depth of water above the sensors, relating as signal inputs to the computer for the control of the ballasting.
12. 12. A WEC according to claim 11, wherein the sensors may be utilizing the hydrostatic head of the seawater column directly above it or with other means of determining the depth of the said column.
13. 13. A WEC according to claim 2 and 3, wherein the wheel is mounted to a shaft, and at least one flywheel is co-mounted on the same shaft, and the flywheel stores kinetic energy as it rotates with the shaft, and releases the same energy to sustain the shaft rotation during the through cycle of the wave flowing inside the duct.
14. 14. A WEC according to claim 13, wherein a chain sprocket or similar power transmission device is co-mounted on one end of the shaft as the driver of a chain or similar drive.
15. 15. A WEC according to claim 14, wherein the chain driven sprocket or similar power transmission device is the driver of a reciprocating pump that draws seawater during the suction stroke and converting the transmitted power through the drive into a stored potential energy in the form of the seawater differential pressure across the pump.
16. 16. A WEC according to claim 15, wherein the pressurized seawater is stored in a hydrophore tank intended for a constant delivery of high pressure seawater irrespective of the wave cycle.
17. 17. A WEC according to claim 16, wherein a portion of the pressurized seawater is utilized to produce utilities for internal WEC use, and wherein the potential energy of the pressurized water is converted into shaft power through an impulse turbine, and wherein the impulse turbine drives an alternator for electricity generation.
18. 18. A WEC according to claim 17, wherein an impulse turbine drives an air compressor for compressed air production.
19. 19. A WEC according to claim 15, wherein the pressurized water from the hydrophore tank is exported through a subsea pipeline to onshore or offshore destination intended for electricity generation or seawater desalination or for cogeneration of desalinated water and electricity.
20. 20. A WEC according to claims 16, or 17, or 18, wherein the intended purpose is to supply electricity or compressed air or pressurized water to complement the operation of an offshore fixed or floating platform.
21. 21. A WEC according to claim 1, wherein, in an event of severe storm can fully submerge to a depth where the load effect of the surface disturbance is allowable on both the WEC and the anchor.
22. 22. A WEC according to all of the preceding claims, wherein the normal mode of operation is remote and autonomous offshore, with wireless or cable link to a base onshore for monitoring of the pertinent parameters relating to its operation.
23. 23. A WEC according to claim 1, wherein the mooring system may be comprised of a chain anchored from seabed to a suction pile or other suitable means of subsea foundation, with the chain connecting the WEC and the anchor.
24. 24. A WEC according to claim 1, wherein the mooring system may be comprised of a rope with metallic or polymer materials, connecting the WEC to a fixed platform leg or to a moored floating platform.
25. 25. A WEC according to claim 1, wherein, according to planned deployment or dry-dock maintenance, the device can be connected to or disconnected from the mooring and export pipeline and can be readily towed to and from the zone of deployment.