Wind and wave desalination vessel

Abstract

The present invention provides a novel floating and renewable energy-powered desalination vessel, which also functions as a wind turbine generator and wave energy generator platform. With energy derived from the wind and waves, the vessel performs reverse osmosis within a vertically positioned cylindrical section extending below a buoyancy chamber. The cylindrical section contains reverse osmosis membranes located above a seawater screening and filtration system, which serve as ballast. The entire vessel and power systems are configured to have the center of mass below the center of buoyancy, forming a vertically stable floating structure with minimum pitch, roll, and wave heave in high sea states. The electric power generated is utilized internally to produce desalinated water or hydrogen from the desalinated water's electrolysis, power an onboard data center, or power delivery to a shoreside power grid. In addition to a wind turbine generator and a wave energy generator, a photovoltaic array or a marine current generator may be utilized to power these applications. Alternatively, the desalination vessel operates with the assistance of shore-based power provided by cable.

Claims

1. A floating vessel comprising: a spar buoy, wherein the spar buoy comprises a cylindrical section and a deck; a tower affixed to the deck of the spar buoy, wherein a vertical axis of the tower and a vertical axis of the cylindrical section are offset, the floating vessel's center of mass is located windward of its center of buoyancy, creating a forward tilt; a wind turbine generator affixed to the tower; a desalination system located in the spar buoy; one or more outriggers connected to the spar buoy, wherein each of the one or more outriggers comprises a float; and an adjustable strut coupling the one or more outriggers to the tower.

2. The floating vessel of claim 1, further comprising a wave energy converter coupled to the adjustable strut.

3. The floating vessel of claim 1, further comprising a pump coupled to the adjustable strut, wherein the pump is in fluid communication with the desalination system.

4. The floating vessel of claim 1, further comprising a thruster affixed to the float of one of the one or more outriggers.

5. The floating vessel of claim 1, wherein the adjustable strut comprises an actuator to adjust a length of the adjustable strut.

6. The floating vessel of claim 5, wherein the actuator to adjust a length of the adjustable strut, adjusts an angle formed between the tower and the one or more outriggers.

7. The floating vessel of claim 1, wherein the spar buoy further comprises a buoyancy chamber and a ballast section, wherein the cylindrical section houses the desalination system, water in the desalination system serves as ballast, and the ballast section comprises a dense mass media filtration system at the base of the ballast section, which is in fluid communication with the desalination system.

8. The floating vessel of claim 7, further comprising a hydrolysis system in fluid communication with the desalination system, wherein hydrogen or oxygen produced by the hydrolysis system is stored in the buoyancy chamber.

9. The floating vessel of claim 1, wherein a vertical axis of the wind turbine generator is offset downwind from a vertical axis of the spar buoy.

10. A floating vessel comprising: a floating platform, wherein the floating platform comprises a cylindrical section and a deck; a tower affixed to the floating platform, wherein a vertical axis of the tower and a vertical axis of the cylindrical section are offset, the floating vessel's center of mass is located windward of its center of buoyancy, creating a forward tilt; a wind turbine generator affixed to the tower; means for adjusting yaw of the tower and the wind turbine generator; means for adjusting pitch of the tower; and wherein the means for adjusting pitch of the tower relative to the floating platform comprises an adjustable strut and one or more outriggers.

11. The floating vessel of claim 10, further comprising a wave energy converter, or a pump.

12. The floating vessel of claim 1, further comprising means for converting seawater into freshwater.

13. The floating vessel of claim 1, wherein the forward tilt is between 5 to 8 degrees to vertical.

14. The floating vessel of claim 10, wherein the forward tilt is between 5 to 8 degrees to vertical.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a complete understanding of the present invention and its advantages, reference is now made to the ensuing descriptions taken in connection with the accompanying drawings briefly described as follows.

(2) FIG. 1a illustrates a floating and renewable energy-powered desalination vessel according to an embodiment of the invention.

(3) FIG. 1b illustrates the floating and renewable energy powered desalination vessel of FIG. 1a with the downwind outrigger float/thrusters to yaw the turbine.

(4) FIG. 2a illustrates a side view of the horizontal and vertical axis of the floating and renewable energy powered vessel of FIG. 1a in a calm, no wind conditions (Region 1, under normal wind conditions (Regions 2 and 3), and the outrigger floats in high wind conditions with the rotor blades feathered (Region 4).

(5) FIG. 2b illustrates the wind turbine power curve in relation to power (y-axis) against wind velocity (x-axis).

(6) FIGS. 2c, 2d, and 2e illustrate i) platform and outriggers pitched 5 degrees with no wind, ii) operation in a normal range of wind speed, and iii) operation in high wind velocity with outrigger floats at maximum submergence.

(7) FIG. 3 illustrates outrigger floats responding to wave heave force to drive a generator separate or in combination with the wind turbine to power the desalination system and includes a view of the platform section in which the surface of the buoyancy chamber and spar is removed to expose an internal, subsurface desalination system.

(8) FIG. 4 illustrates low wind shear on the rotor with no rotor plane vertical adjustment and rotor plane back pitch adjustment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(9) Preferred embodiments of the present invention and their advantages may be understood by referring to FIGS. 1-4, wherein like reference numerals refer to like elements. The present invention may be deployed in any water environment, preferably where one or more renewable energy sources are available. Pipeline connection to a shore-based water offtake infrastructure is required unless at-sea water delivery is available, for example, for a cruise ship water supply. Connection to an onshore electrical grid is optional.

(10) The present invention provides a novel topology for integrating a desalination system with a renewable energy generator, such as a wind turbine on a tower mounted on top of a spar buoy. Compelling synergies result from this integration. Offshore wind turbines require high stability with minimum pitch, roll, and heave in response to sea states and must also be resistant to the wind's overturning force against the wind turbine's rotor and tower. Among other advantages, the present invention adjusts the wind turbine's wind-induced pitch/tilt via one or more reactive struts connected to hinged outrigger floats. The inclusion of a wave electric generator coupled in the strut offers added electric power generation with minimal additional cost beyond the generator, controls, and integration in the power supply. The present invention may also implement other types of renewable energy generators such as, but not limited to, a solar photovoltaic array or a marine current turbine generator.

(11) FIG. 1a illustrates a floating and renewable energy-powered desalination vessel 100 according to an embodiment of the invention. The vessel 100 comprises a wind turbine generator (WTG) 110 with rotor blades 112, a tower (mast) 120, a spar buoy 130 including a main buoyancy section 132, a cylindrical section 134, and a ballast section 136, and one or more outrigger legs 140, preferably at least two, coupled to the spar buoy 130 and mast 120 via a hinge 138. One or more floats or pontoons 142, preferably one, is attached to a distal end of each outrigger leg 140, which together provide a downwind, outboard buoyancy moment force for resisting the tower overturning moment induced by wind thrust on the WTG 110. Disposed on one or more of the pontoons 142 is a marine thruster 144. The mast 120 is rigidly attached to the spar buoy 130 to form the central structure through which wind loads on the WTG 110 are conveyed to the outriggers 140.

(12) Above the ocean surface, deck 133 of the buoyancy chamber 132 joins the mast 120 on which mounts the tower base of the WTG 110. A reactive strut 150 between the mast 120 and outrigger legs 140 and pontoons 142 is extended or contracted in length by a hydraulic or mechanical actuator 152 to react to wind thrust loads. The actuator 152 may be hydraulic or electric/mechanical to extend or contract the strut 150 for tower 120 angle adjustment to wind loading, wind shear, and sea states. Wind shear is monitored to ensure the wind turbine rotor plane maintains uniform or near-uniform wind velocity across the rotor's vertical plane. Such rotor plane pitch adjustment to wind shear and wind thrust loads is novel and results in higher turbine productivity and reduced fatigue of the blades 112, as described below.

(13) The strut 150 is coupled to the outriggers 140 via a crossbar 154. However, in other embodiments of the invention, each outrigger 140 is connected to the spar buoy 130 via a separate hinge 138, and the crossbar 154 is not necessary. In this configuration, each outrigger 140 has its own respective strut 150. Yet, any number, combination, or composition of hinges 138, outriggers 140, struts 150, pontoons 142, and thrusters 144 may be employed with or without crossbars 154. The strut 150 may include a linear motor/generator 153 and a braking system on the strut actuator 152 to maintain the optimum tower pitch angle. The heaving motion of the outrigger floats 142 resulting from the hydrodynamic excitation force from waves drives the linear motor/generator in the strut 150 floats 142. Static position offsets to the strut 150 length for wind load compensation may be applied through a variable position braking system 152, leaving a small operating stroke band for wave energy conversion. In an embodiment of the invention, the strut 150, rather than containing an electrical linear generator, may use a hydraulic pump 153 driven by wave heave on the outrigger float(s), acting independently from the strut length adjustment, which compensates for rotor wind thrust loads and rotor plane pitch adjustment. The vertical rotor plane angle adjustment may obviate or reduce the need for a cyclic blade pitch mechanism, reducing blade pitch mechanism 110 mass while increasing wind energy capture.

(14) FIG. 1b illustrates the marine thrusters 144, the identification and implementation of which are apparent to one of ordinary skill in the art. The marine thrusters 144 are mounted on the pontoons 142 and aligned to provide thrust in a direction 145 tangential to the arc of the outriggers 140 between the vertical centroid of the spar buoy 130 and the vertical centroid turbine tower 120. The thrusters 144 provide tangential force to yaw the entire floating wind turbine 110 and renewable energy powered desalination vessel 100 to face the wind or another direction. Wind direction is monitored to maintain a perpendicular or near perpendicular plane of the rotor blades 112 to the wind direction. When a wind direction shift is detected between the vessel's actual azimuth and desired azimuth angle, a controller sends a yaw command to the thrusters 144 to drive the azimuth error to zero.

(15) The horizontal translation of the spar buoy 130 is restricted by a slip collar (not shown) and mooring lines (not shown), the implementation of which is apparent to one of ordinary skill in the art. The slip collar and mooring lines only allow rotational movement of the spar buoy 130.

(16) FIG. 2a illustrates that the pitching of blades 112 along with the tower 120 to outrigger 140 angle modification by strut actuator 152 serves to manage turbine input power, structural loads, and vessel 100 motion in response to wind and sea state. Blade pitch and generator reaction torque determine rotor shaft input torque and speed and, therefore, the wind kinetic energy into the wind turbine 110, driving the generator. These related actions are demonstrated by the wind turbine 110 power curve, as shown in FIG. 2b, progressing through four operating regions, depending on wind speed. Region 1—wind below cut-in speed, where the generator is off-line. Region 2—operational wind speed of the turbine is below rated power, and here, the blade pitch is maintained at a fixed position, and the generator is on-line, below the rated power. Region 3—wind speed is above rated power, the blades de-pitch, and the generator's back-torque is actively controlled to manage input rotor torque/speed to maintain the generator output at rated power. Region 4—wind above cut-out speed, has blades de-pitched to feather, and the generator is off-line.

(17) FIGS. 2c, 2d, and 2e illustrate that in Region 1, with the forward tilt/pitch 113, the outrigger floats 142 are raised above the water surface with thrusters 144 still submerged. As wind speed increases to Region 2 above turbine cut-in speed, the floating turbine platform/tower is righted from the forward tilt/pitch 113 of say 5 to 8 degrees, to vertical 114.

(18) Forward pitch/tilt is due to the center of mass 137 located forward/windward of the center of buoyancy 135. With rising wind speed, in the lower end of power Region 2, the platform/tower rotates toward vertical 114 driven by the wind's force on the rotor. As wind speed continues to increase in Region 2 and 3, the turbine controller commands the strut actuators 152 to progressively increase the outrigger 140 angle to the tower, causing the pontoon floats 142 to submerge further, increasing the counterforce needed to maintain vertical or near-vertical tower angle. At the turbine cut-out wind speed of Region 3, the blades are feathered, the turbine generator goes off-line, and the outriggers 140 return to a 90-degree angle to the tower 120, as commanded by the controller. This mode is maintained throughout the period of high wind speeds in Region 4, with the thrusters maintaining the turbine facing the wind. As the wind dies down to Region to 2 or 3, operation is resumed as indicated in the foregoing, or windspeed below Region 2 results forward tower tilt with the wind as in Region 1. There may be some variations to this protocol depending on wind turbulence and sea state.

(19) The mass of the tower 120 and the turbine 110 is offset to the upwind mass of the spar 130, and the connecting buoyancy chamber 132 is configured for a buoyancy volume distribution that is proportionately greater near the tower axis, than towards the spar axis. This buoyancy chamber volume distribution is made by widening (or deepening—not shown) the buoyancy chamber 132 around the axis of the tower 120, with the combined effect of shifting the center of mass forward. This arrangement results in the center of buoyancy 135 being closer to the tower 120 than to the spar 130, while the center of mass 137 is located sufficiently below the center of buoyancy 135 to provide the required vertical stiffness under all wind and sea state conditions. This spar-tower offset has the effect of cantilevering the mass of the spar 130 upwind to add resistance to the overturning moment of the wind thrust on the turbine/tower of vessel 100, which allows for reduced outrigger float 142 capacity and less spar ballast 136 and/or a shorter spar 134.

(20) FIG. 3 shows the struts 150 comprises an internal electrical generator 153 (hidden from view) to convert wave heave energy to electric power. For example, the linear electrical generator 153 utilizes the heave energy from ocean waves 143 to drive magnets through a stator and converts linear motion into electric power, the implementation of which is apparent to one of ordinary skill in the art. Wave energy capture is based on the limited vertical motion response of the spar buoy vessel 100 to waves' heave force. Thus, the vessel provides a stable base for a wave generator to react against to convert the wave energy. Power generation by wave energy may also be accomplished with a rotary generator, a hydraulic piston, and hydraulic motor, or a mechanical method such as a rack and pinion mechanism to drive a generator. The driving float of these power take-off systems may connect the float by other means to the power take-off system and may be located on other parts of the spar vessel which it reacts against.

(21) Superimposed on the turbine controller's wind force response commands to maintain vertical or near-vertical tower angle and optimized rotor plane pitch, sea state response commands are implemented to not only cause the reaction of strut actuators 152 to drive tower-outrigger 140 angle changes but also to respond to wave heave 143 inputs. The strut actuator 152 primarily maintains the vertical positioning of the tower 110. The strut actuator 152 responds to generally slower and less frequent changes of the wind force. In contrast, the linear generator 153 is driven by the short periodic heave force of the waves 143 on the floats 142 with resulting forces induced in the outriggers 140 counteracted to generate electrical power. This wave-driven power is additive to the wind-turbine-generated power and extends power capacity in periods when the wind speed diminishes and wave action continues.

(22) The operation of wind turbine generator 110 and the outrigger floats 142 driving generator 153 provides the electric power for the desalination vessel 100. The cutaway view of the desalination vessel 100, in which the surface of the cylindrical section 134 is removed to expose an internal, subsurface desalination system 200 comprising a plurality of RO membrane tubes 210. In an embodiment of the invention, the cylindrical section 134 may be narrower than the buoyancy section 132 and the ballast section 136, thereby concentrating the center of buoyancy nearer to the water surface and the ballast further from the surface, which is essential to the vertical stability of the floating wind turbine powered vessel 100. The ballast section 136 contains high-density material and forms the base of the spar buoy 130. Cylindrical section 134 in this embodiment is neutrally buoyant. Therefore, below the cylindrical section 134 is the heavy ballast section 136 with seawater screening inlet ports 220 feeding the desalination system 200 through a heavy media filtration bed (not shown) contained within the ballast section 136. The media filtration bed contains sand, gravel, and other dense material through which seawater filtration occurs. Filtered seawater is pumped to the RO membrane tubes 210, aggregated in packs of tubes to facilitate efficient extraction through a hatch 211 to the surface deck for replacement during servicing.

(23) With power for the desalination system 200 supplied by the wind turbine 110 and the wave-driven generator 153, the vessel 100, if connected to shore power, can deliver a combination of fresh water and electric power, thus, altering the ratio to meet time-of-day or the seasonal most valued need.

(24) FIG. 4a shows low wind shear 115 and no adjustment to the vertical axis of the tower 120 by the strut actuator 152. FIG. 4b illustrates that in response to high vertical wind shear 115 across the rotor blade plane of the turbine 110, to minimize rotor blade cyclic structural loads due to wind-shear, the strut actuator 152 may be commanded to reduce the tower-to-outrigger angle by a few degrees, tilting the tower downwind. This compensates for wind shear, causing excessive wind thrust loading of the upper region of the rotor plane relative to the lower region. A conventional way to reduce differential loading across the rotor's vertical plane is for the blades to be pitched on every revolution to spill the higher velocity wind in the rotor plane's upper region. The wear and fatigue on the blade pitch system are appreciated when considering a 30-to-50-ton blade pitching a few degrees 6 to 12 times per minute. Present wind turbines are not designed to alter the vertical rotor, only the horizontal by yawing. By tilting back the plane of the rotor, it allows the vector of rotational movement of the blades to align with changes in wind velocity due to shear, creating a net reduction of wind velocity in the upper region and increase the net velocity in the lower region of the rotor plane, resulting in a reduction in the differential of shear loading at the blade's outer end, as it travels between the upper and lower regions.

(25) Windspeeds typically increase with height above the water surface, resulting in wind shear due to the frictional drag on the water surface. Adjusting for wind shear, as an example, the actuator 152 contracts the strut 150 to decrease the angle between the tower 120 and the outriggers 140 from ninety degrees (90°) to eighty-five degrees (85°), where the rotor plane angle of the WTG 110 has the effect that a blade 112 in the six o'clock position, as it rotates up, effectively retreats from the increasing wind speed, offsetting the increasing windspeed to the twelve o'clock position. There, as it rotates down, the blade 112 advances slightly into the slowing wind speed until it reaches six o'clock again. Rotor plane vertical adjustment helps even-out cyclic wind shear loads on the blades 112, reducing structural fatigue, simplifying the blade/pitch system, and reducing the hub/pitch system's structural fatigue, often a source of the high maintenance of the WTG 110.

(26) The desalinated water produced onboard the vessel 110, combined with the renewable energy captured by the wind turbine and wave-driven generator, can also supply the power for onboard electrolysis equipment to use desalinated water to produce hydrogen and oxygen. This “green hydrogen” may be generated by the vessel 100 with pressurized hydrogen stored in the buoyancy chamber 132. Marine transport vessels are beginning to transition away from carbon fuels, with some early adopters using hydrogen with fuel cells to generate electric power for propulsion. Hydrogen production by the vessel 100 provides at-sea transport vessel fueling and can also be delivered by pipeline to shore-based uses.

(27) In another embodiment of the invention, the buoyancy chamber 130 may also contain data servers powered by the onboard wind and wave energy converters and efficiently cooled by seawater. Also, onboard battery storage or hydrogen fuel cells may be included as standby power capacity.

(28) In an embodiment of the invention, deployment of the vessel 100 is by horizontal positioning with the outriggers 140 and pontoons 142 folded toward the tower 120. The reaction strut 150 disconnected from the mast 120 and held fast against the turbine tower base 133. In this position, unballasted vessel 100 is towed to its operating site, where the mooring lines, power cables, water delivery pipeline are connected, and the ballast section 136 is filled with water. This serves as variable ballast, shifting the center of mass to the lower end of the vessel 100, causing rotation to a vertical operating position.

(29) With the vessel 100 in a vertical position, the media filter bed is loaded with gravel, sand, etc., displacing a portion of the seawater ballast. The media filter bed loading is performed on the surface, transferring sand, gravel, etc., through a chute to the media tanks. The RO system 200 is designed for years of operation with periodic media filter back-flushing and filter material replacement as it is depleted over time.

(30) Once vertical, the struts 150 are connected, and the vessel 100 is ready for turbine mounting, now a well-developed process with specialized turbine delivery crane ships.

(31) In an embodiment of the invention, the controller is implemented as a microcontroller or a system on a chip, the implementation of which are apparent to one of ordinary skill the art.

(32) The invention has been described herein using specific embodiments for illustration only. However, it will be readily apparent to one of ordinary skill in the art that the invention's principles can be embodied in other ways. Therefore, the invention should not be regarded as limited in scope to the specific embodiments disclosed herein; it should be fully commensurate in scope with the following claims.