WO2021231102A1 - Stabilisation de jambe de tension en porte-à-faux d'un convertisseur d'énergie houlomotrice flottant ou d'une base de turbine éolienne flottante - Google Patents

Stabilisation de jambe de tension en porte-à-faux d'un convertisseur d'énergie houlomotrice flottant ou d'une base de turbine éolienne flottante Download PDF

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Publication number
WO2021231102A1
WO2021231102A1 PCT/US2021/030135 US2021030135W WO2021231102A1 WO 2021231102 A1 WO2021231102 A1 WO 2021231102A1 US 2021030135 W US2021030135 W US 2021030135W WO 2021231102 A1 WO2021231102 A1 WO 2021231102A1
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WIPO (PCT)
Prior art keywords
buoyant body
base
wave
buoyant
wec
Prior art date
Application number
PCT/US2021/030135
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English (en)
Inventor
John W. Rohrer
Original Assignee
Rohrer Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US15/930,752 external-priority patent/US11131287B2/en
Application filed by Rohrer Technologies, Inc. filed Critical Rohrer Technologies, Inc.
Publication of WO2021231102A1 publication Critical patent/WO2021231102A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/005—Equipment to decrease ship's vibrations produced externally to the ship, e.g. wave-induced vibrations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D13/00—Assembly, mounting or commissioning of wind motors; Arrangements specially adapted for transporting wind motor components
    • F03D13/20—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
    • F03D13/25—Arrangements for mounting or supporting wind motors; Masts or towers for wind motors specially adapted for offshore installation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/04—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull
    • B63B2001/044—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull with a small waterline area compared to total displacement, e.g. of semi-submersible type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B2021/001—Mooring bars, yokes, or the like, e.g. comprising articulations on both ends
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B2035/4433—Floating structures carrying electric power plants
    • B63B2035/446—Floating structures carrying electric power plants for converting wind energy into electric energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B2035/4433—Floating structures carrying electric power plants
    • B63B2035/4466—Floating structures carrying electric power plants for converting water energy into electric energy, e.g. from tidal flows, waves or currents
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2240/00—Components
    • F05B2240/90—Mounting on supporting structures or systems
    • F05B2240/93—Mounting on supporting structures or systems on a structure floating on a liquid surface
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/727—Offshore wind turbines

Definitions

  • This disclosure relates to an improved means to stabilize a floating or semi- submerged apparatus, such as a floating wave-energy-converter (WEC) base or a floating offshore wind-turbine (FWT) base, against undesirable wave or wind-induced motion including heave, surge and/or pitching motions. Such undesirable motions can reduce the effectiveness or energy capture efficiency of floating renewable wave or wind-energy capture devices.
  • WEC floating wave-energy-converter
  • FWT floating offshore wind-turbine
  • the disclosure is not limited to WEC or FWT bases and may be utilized to motion-stabilize other floating or semi-submerged bases, platforms or rafts. More particularly, the disclosure relates to an improved means of motion controlling or stabilizing floating or semi-submerged bases for combined WECs and FWTs. The disclosure also relates to improved combinations of WECs and WTs that use a common stabilized base.
  • Ocean waves are produced by offshore winds. Waves near the ocean surface typically have 5-10 times the energy density (kw/m 2 ) of offshore winds that produce such waves.
  • the offshore wind-energy resource has higher energy content and is more consistent than terrestrial winds.
  • Offshore wind farms are now the major source of renewable power capacity additions in Europe where unsubsidized offshore wind power is now competitive with fossil fuel alternatives.
  • the 30 MW Block Island Wind Farm is the first and only operating U. S. offshore wind farm to date. Almost all large offshore wind farms to date have been deployed in water depths below 50 meters where seabed fixed bases (mono-piles, jacket structures, or tripods) are feasible. The vast majority of U. S.
  • Wave energy is also a huge global renewable energy resource but, despite its higher energy density, lags offshore wind development with no large utility-scale-wave energy farms yet commercially deployed. This is due both to the profusion of distinctly different proposed means of converting ocean waves into electrical power and to the high capital cost (CapEx) per installed megawatt (MW) of those primitive early generation WECs which have been scaled-up and ocean-deployed to date. WECs also have unique marine design challenges. Ocean wave energy is most concentrated on the ocean surface and decreases exponentially with depth, thereby making it most desirable to deploy WECs on the surface. Wave energy, however, is proportional to wave height squared. A WEC designed for peak output in 4-meter (significant wave height) seas must survive (or avoid) 16 times higher structural loads during occasional severe winter storms that produce wave heights 4 times higher than the 4-meter design wave height.
  • All WECs require at least one first active body, typically a buoyant float or flap, and a second reaction body or mass, typically a second floating body, a frame, a base, a platform, or a shoreline or seabed -affixed frame, tower, or base, or the seabed itself.
  • Wave energy is captured from the wave-induced relative motion, between the first active body and the second reaction body that drives a power take-off (PTO) device such as an electric generator, a hydraulic pump, or an air turbine.
  • PTO power take-off
  • WEC wave energy capture efficiency is also substantially reduced by unwanted wave or wind-induced heave (vertical), surge (lateral), and/or pitching (rotational) motion of the WEC reaction body (which can be a floating or semi-submerged frame, base, raft, or platform).
  • unwanted wave or wind-induced reaction-body motion will substantially reduce the relative motion between a WEC’s first or active body (such as a flap or a float) and the WEC’s reaction body.
  • captured wave energy is the product of the relative motion between the active and reactive body times the resistive force (applied by the generator or other power take-off means) between the two (or more) bodies, any reduction in the relative motion between the bodies (caused by wave-induced heave, surge, and/or pitching motion of the reactive body) reduces wave energy capture.
  • FWTs or WECs One way of motion-stabilizing the floating or semi-submerged base or reaction body of FWTs or WECs is to make them massive. This can be done by the sheer weight of the metal (or concrete) used to fabricate them which can be further enhanced by integral or attached water ballast tanks or drag plates that capture or entrain additional seawater mass (as shown in FIG. 1 Semi-Submersible). Unfortunately, the fabricated marine steel, aluminum, fiberglass, and/or concrete utilized in such massive FWT or WEC bases often makes the bases more massive and expensive than their wind turbines or WEC floats or flaps that do the actual energy capture work.
  • Wind and wave energy resources may be free, but the capital required to capture and convert these renewable resources into usable power is not free.
  • the cost of ocean-energy-produced power (often referenced as the LCOE or Levelized Cost of Energy) is primarily determined by the installed capital cost or expense (CapEx)/unit of output or CapEx/MW) required to capture, convert and deliver it. Even FWT and WEC operating and maintenance expenses are a relatively fixed percent of their CapEx.
  • the seabed itself can also be utilized as part of the base or reaction-body mass to stabilize FWT and WEC bases or reaction bodies.
  • the Tension Leg Platform shown in FIG.1 utilizes three tensioned cables affixed to the seabed to stabilize a buoyant, fully-submerged platform to which a wind turbine tower is mounted.
  • the seabed is certainly massive and immobile, but the large buoyant platform with its three tensioned legs are not without substantial mass or CapEx.
  • the three tensioned leg cables and their secure attachments to the seabed are also not without costs. These tension legs must be able to withstand tidal changes in platform-submerged depth and severe “snap loads” from occasional, but severe, sea conditions that produce waves up to 15 meters in height that slacken and then suddenly re-tension these cables.
  • the descriptions and operating principles of the present disclosure focus primarily on the stabilization of FWT bases, WEC floating bases, or combined FWT and WEC devices that utilize a common floating, semi-submerged, or buoyant base by use of at least one up-sea, substantially submerged, cantilevered mooring beam connected to a substantially submerged, buoyant mooring buoy connected to the seabed by at least one tensioned leg or cable.
  • the disclosure also includes application of these components and principles to stabilize other buoyant, semi-submerged, moored platforms or bases from undesirable wave or wind-induced motions.
  • One object of the disclosure is to provide an effective means to motion- stabilize or motion control an FWT base, WEC base, a combination FWT-WEC base or other floating platform or base from undesirable wave or wind-induced motion while minimizing the structural mass and CapEx of such platform or base.
  • Another object of the disclosure is to provide a mooring system for a motion-stabilized base that enhances such base stabilization against wave or wind-induced motion.
  • Yet another object of the disclosure is to effectively utilize the gyroscopic effect of a rotating FWT to further stabilize the FWT or combined FWT-WEC base against wind gust or wave-induced aft-ward pitching or other undesirable motion.
  • Another object of the disclosure is to provide a base mooring system that allows a WEC, FWT, combined FWT-WEC base, or other floating base to pivot or swivel in a horizontal plane around a mooring point or buoy to self-orient or weather-vane into oncoming wave fronts to either improve base stabilization or to increase WEC capture efficiency by allowing the WEC to intercept maximum oncoming wave-front width.
  • a mooring system concurrently enhances the motion stabilization of such a base.
  • Yet another object of the disclosure is to provide a base mooring system that allows a WEC, FWT, or combined FWT-WEC base to pivot or swivel in a horizontal plane around a mooring point or buoy to self-orient or weather-vane into oncoming wave fronts or wind gusts while extending the fore-to-aft dimension of such a single or multiple-base float by utilizing the disclosed mooring beam.
  • Such an elongated fore-to-aft dimension spans a significant portion of oncoming wave lengths and thereby reduces fore-to-aft pitching of such a base or frame.
  • a further object of the disclosure is to provide a WEC, FWT, combined WEC-
  • FWT base or other floating-base mooring system that provides self-orientation of such base into oncoming wave or wind about a mooring or pivot point or buoy, and concurrently provides base motion stabilization by utilizing one or more tensioned cables between the seabed and such mooring or pivot point.
  • a base is pivotably connected to such a mooring point by a semi-rigid mooring beam that is rigidly connected to such a base.
  • a still further object of the disclosure is to provide a WEC, FWT, combination
  • WEC-FWT base or other floating-base mooring system with at least one mooring beam and at least one tensioned cable from the seabed to a submerged mooring point.
  • the chosen length of such mooring beam and the chosen depth of such mooring point is chosen such that the moment produced about the mooring point by wave surge (lateral) forces and optionally by wind forces or loads acting upon such base, and upon any WEC or FWT attached to such base, is at least partially countered by the opposing moment about such mooring point produced by wave heave (vertical) forces or loads acting upon such base, and upon any WEC or FWT attached to such base.
  • Another object of the disclosure is to provide a combination WEC-FWT, wherein the WEC is comprised of one or more adjacent surface floats oriented or self- orienting towards prevailing or oncoming wave fronts, which floats, individually or in combination, have a wave-front width, or beam, substantially exceeding their fore-to-aft depth, excluding appendages.
  • Such float(s) are connected to a common WEC-FWT base by one or more swing or drive arms at a pivot point within, or attached to, such base substantially below the still water line (SWL) and substantially aft (down-sea) of the center of buoyancy of such float(s).
  • Such a base is pivotably connected by an elongated mooring beam to a forward (up sea) mooring point or buoy connected to the seabed by at least one tensioned cable.
  • a floating base or platform such as a WEC base, FWT base, or combination WEC-FWT base motion- stabilized or controlled against wave or wind-induced motions. It is further desirable to have such bases be as light-weight and inexpensive (low CapEx) as possible. Multiple tensioned leg or cable connections between the base and the seabed can provide supplemental seabed stabilization mass for such a base but will restrict desirable self orientation (weather-vanning) of the base and any attached WEC device. WEC self orientation is desirable because it allows wide-beam WEC surface floats to intercept maximum wave-front-containing wave energy per unit of float volume, mass, and cost (CapEx).
  • WECs must absorb a majority of both heave and surge wave-energy components, each of which is equal to exactly half of the total wave energy in deep water, which makes WEC base lateral motion stabilization essential.
  • Multiple tension-leg-moored bases or floats do not compensate for tidal changes in the still water level or line (SWL), which change can change the submerged depth of such bases and significantly reduce the efficiency and effectiveness of WECs that utilize such bases as their reaction body.
  • the disclosure provides a relatively low-mass, low-CapEx, effectively motion- stabilized or motion controlled floating or semi-submerged base or platform that can be utilized as an FWT base, WEC base, or combination FWT-WEC base.
  • Undesirable, excessive base-stabilization mass is reduced by pivotably connecting the base to an up-sea submerged mooring buoy or pivot point that utilizes an elongated mooring beam rigidly attached (cantilevered) to the base.
  • the mooring buoy is attached to the seabed by at least one tensioned leg (or cable).
  • the up-sea horizontal pivoting attachment between the elongated mooring beam and the submerged mooring ball or pivot point allows any WEC surface floats on the motion-stabilized, low-mass base to remain self-oriented (weather vanning) into oncoming wave fronts, which maximizes intercepted wave-front width, and may allow self-orientation of one or more FWTs on such a base.
  • the elongated, cantilevered mooring beam of the disclosure also allows for significant tidal SWL adjustment because the mooring beam length can be substantially longer than the tidal range, which is particularly necessary for WECs.
  • the disclosure has additional novel and unique synergistic advantages when a combined WEC-FWT is combined with the disclosed stabilized base.
  • the rotational inertia of an FWT on a base enhances base stabilization against pitch (gyroscopic effect).
  • Adjustment of the mooring beam length or base seawater ballast allows optimum FWT horizontal axis adjustment.
  • the mass of the FWT on top of its tower substantially increases the moment of inertia and increases the natural frequency of the combined FWT and base substantially reduces wave-induced aft pitching, which, in turn, increases the WEC float-to- base relative motion and energy-capture efficiency, especially for large waves and long wave periods where most WECs struggle.
  • Base pitch, heave stability and attitude of the disclosed apparatus can be further enhanced by admission or discharge of seawater ballast from at least one cavity within the base or by using one or more substantially horizontal or vertical-plane drag plates affixed to, or extending from, the base.
  • Embodiments of the present disclosure utilize a concave WEC float aft wall, which together with any lower extension thereof, and with optional WEC float side plate aft extensions, further reduce base aft pitching.
  • This concave rear float wall approximately concentric about the drive arm pivot point, fully eliminates or substantially reduces generation of any aft or back waves during the float’s movements, which back wave generation would otherwise substantially reduce WEC wave-energy capture efficiency.
  • a semi-submerged substantially vertical mono-spar is utilized as the base.
  • An upward extension of such a mono-spar provides the necessary vertical tower for at least one FWT.
  • Use of this mono-spar base when dimensioned with an appropriate width, allows the floats to rotate a complete 360° past the mono-spar base, above or below the float drive-arm pivot point, without physical interference between the floats, drive arms, and mono-spar base. This eliminates the severe-seas “float-to-base end-stop collision problem” that almost all other WECs that utilize surface floats must overcome.
  • the mono-spar base configuration also allows the floats, with their elongated drive arms, to be rotated and fully submerged well below oncoming storm-wave troughs and well below the drive-arm pivot point. Float submergence can be further facilitated by flooding the floats with seawater ballast to reduce their buoyancy.
  • FWT-WEC combinations combine one of the three basic FWT floating bases shown in FIG. 1 with early-generation, intrinsically-high-CapEx, low-capture- efficiency WECs such as Oscillating Water Columns (OWCs), ring buoys, other axis- symmetric buoys, or hinged surge flaps.
  • WECs Oscillating Water Columns
  • ring buoys other axis- symmetric buoys
  • hinged surge flaps such as Oscillating Water Columns (OWCs), ring buoys, other axis- symmetric buoys
  • surge flaps capture primarily surge wave energy, each representing only half of the total wave energy in still water.
  • FIG. 2 shows the Floating Power Plant (FPP) of Denmark, which represents one of several dozen proposed combinations of FWTs and WECs. It is one of the few FWT-WEC combinations that self-orients (weather vanes) into oncoming wave fronts.
  • This combination FWT-WEC like most FWT-WEC combinations, utilizes a common massive and costly semi-submerged frame, base or platform (resulting in high CapEx/MW) made up of multiple connected buoyant, semi-submerged bodies, similar to the relevant art Spar-Submersible FWT base shown in FIG. 1.
  • the FPP utilizes multiple slack mooring lines and thus cannot utilize seabed mass to supplement more expensive frame or base mass like the apparatus of the disclosure.
  • the FPP WECs have float pivot points forward (up-sea) of the float center of buoyancy and at (or above) the SWL (unlike the aft pivot points substantially below the SWL of the disclosure).
  • This WEC configuration results in substantially lower inherent wave-energy-capture efficiency because the energy capturing floats cannot move concurrently both upwardly and rearwardly on each wave crest and return downwardly and forwardly into each successive wave trough to thus capture both heave and surge wave energy for maximum capture efficiency.
  • the FPP also lacks the concave float back of the disclosure, which prevents undesirable generation of back waves, which further reduces wave energy capture efficiency.
  • the FPP WEC floats cannot rotate 360° without interference and are not submergible below wave troughs like the apparatus disclosed herein. Absent the ability to rotate freely about 360°, the FPP WEC floats are subjected to both severe sea end-stop collisions and other damage as they attempt to survive severe storms on the ocean surface.
  • FIG. 3 a WEC is shown identical to the WEC embodiment shown in FIG. 5 US Application No. 16/153,682, of which this Application is a Continuation- in-Part.
  • This WEC frame or base includes a single substantially vertical buoyant spar (mono-spar) designated concurrently as 100, 20, rigidly connected to a lateral forward- protruding (cantilevered) mooring beam 107 connected at its up-sea or forward end to a buoyant (shown submerged) mooring buoy 112, which mooring buoy is connected to the seabed by at least one tensioned leg cable 110.
  • FIG. 1 substantially vertical buoyant spar designated concurrently as 100, 20, rigidly connected to a lateral forward- protruding (cantilevered) mooring beam 107 connected at its up-sea or forward end to a buoyant (shown submerged) mooring buoy 112, which mooring buoy is connected to the seabed by at least one tensioned leg cable 110.
  • FIG. 1 substantially vertical buoyant
  • the length of the lateral mooring beam 107 and the elevation of its up-sea connection point to mooring buoy 112 establishes favorable concurrently-opposing, heave-and-surge-induced moments about 112 that substantially reduce or eliminate wave-induced heave, surge, and pitching motion of the mono-spar frame 100, 20.
  • the Solo Duck utilizes a single asymmetric cam shaped wide float that surrounds a stationary cylindrical reaction body.
  • the original Duck utilized multiple adjacent floats.
  • the Solo Duck float like its predecessor the Salter Duck, moves both upwards and aft-wards in response to oncoming wave crests.
  • the cylindrical base or reaction body must be kept relatively stationary as the float rotates about it for large relative motion necessary for acceptable energy capture.
  • One proposed configuration of the Solo Duck uses two arms that protrude downwardly from the cylindrical reaction body- each arm is connected to the seabed using tensioned cables or legs.
  • the Solo Duck configuration does not provide self-orientation (weather- vaning) of the WEC into oncoming wave fronts and lacks the ability to maintain a constant submerged depth of the reaction body during tidal changes to the SWL. It also is ineffective in stabilizing the massive cylindrical reaction body against wave heave-and-surge-induced motion and was, therefore, replaced by a single large area drag plate located substantially below the reaction body and connected to it as explained in Numerical and Experimental Study of the Solo Duck Wave Energy Converter, Energys, 21 May 2019, Wu, Yao, Sun, Ni, and Goteman.
  • FIG. 1 are isometric views, both above and below a still water line, of three relevant art apparatuses.
  • FIG. 2 is a side view in elevation of the relevant art Floating Power Plant (FPP) of Denmark (P37 or P80 model), an FWT-WEC combination that utilizes a large buoyant multi-body base or platform to which one or more FWT and WECs are attached.
  • FPP Floating Power Plant
  • FIG. 3 is a side view in elevation of a WEC according to the embodiment disclosed in FIG. 5 of US Application 16/153,682.
  • FIG. 4A is a side view in elevation of a WEC according to the embodiment disclosed in FIG. 8A and 8B of US Application 16/153,682 that includes a longer mooring beam and shallow mooring ball submerged depth producing a larger vertical heave wave force moment and smaller lateral surge wave force moment about the mooring ball.
  • FIG. 4B is a side view in elevation of a WEC according to the embodiment shown in FIG. 8A of U.S. Patent Application Serial No. 16/153,682 that includes a shorter mooring beam length and deeper mooring ball submerged depth producing a smaller vertical heave wave force moment about the mooring ball and a larger lateral surge force moment about the mooring ball.
  • FIG. 5 is an isometric view of a combined FWT-WEC apparatus according to one embodiment of the disclosure utilizing the cantilevered tension leg of the present disclosure utilized to motion stabilize a mono-spar semi-submerged base.
  • Optional horizontal and/or vertical drag plates are utilized at or near the bottom of the base and on the mooring buoy.
  • Optional secondary tensioned mooring lines are attached near the bottom of a spar extending below the mooring buoy.
  • FIG. 6 is a side view in elevation of the combined FWT-WEC apparatus shown in FIG. 5.
  • FIG. 7 is a plan view of the combined FWT-WEC apparatus shown in FIG. 5.
  • FIG. 8 is a side view in elevation of a WEC according to another embodiment of the disclosure of the present disclosure showing an optional shoaling plane preceding the floats and an optional elongated mooring buoy spar extended aft of the mono-spar base with optional attached horizontal or vertical drag plate surfaces.
  • the Spar-Buoy is employed by Equinor in their Hywind Scotland project using five 6MW FWTs. It utilizes a buoyant semi-submerged elongated vertical spar, with a typical submerged depth of 1/3rd to 2/3rds the length of the above SWL wind turbine tower.
  • the submerged spar section is typically of hollow construction with at least the lower portion having one or more cavities for the admission (and expulsion) of seawater ballast.
  • High density solid ballast typically metal or concrete
  • the Spar-Buoy semi-submerged base is slack moored via multiple cables.
  • the Semi-Submersible is comprised of multiple, vertically-oriented semi- submerged hollow spars (typically three) commonly constructed of marine steel or steel reinforced marine concrete. Like the prior Mono-Spar, internal seawater ballast is used to increase mass and/or to level the wind turbine tower attitude and to compensate for wind or wave-induced pitching. Because its multiple interconnected vertical spars do not protrude as deeply into the water column as the Mono-Spar, a horizontal-plane drag plate or plane is commonly placed on the bottom of each spar to reduce vertical heaving of the Spar-FWT assembly. The FWT tower is commonly located either between the multiple spars or above one of them. Each of the semi-submerged vertical spars is slack moored via multiple cables. It thus cannot utilize seabed mass for stabilization and is not self-orienting.
  • the Tension Leg Platform commonly has three or four seabed-affixed tensioned legs or cables to maintain a majority of the buoyant platform at a submerged depth below the SWL and anticipated wave troughs.
  • Tension Leg Platforms are used extensively for oil and gas exploration and production platforms.
  • other relevant art apparatuses place one or more FWTs on large-surface-area floating barges (or surface platforms made from multiple interconnected floating bodies). WECs also can be attached to these barges.
  • FIG. 2 a schematic of the Danish Floating Power Plant P80 is shown as derived from the floatingpowerplant.com website.
  • WECs and FWTs have been proposed (no large-scale commercial units are yet operating), with most combining one of the generic FWT base designs shown in FIG. 1 above with one of the generic early generation WEC designs, e.g., Oscillating Water Column (OWC), Surge Flaps, Vertically-heaving Buoys, or Articulating Floats.
  • Oscillating Water Column Oscillating Water Column (OWC), Surge Flaps, Vertically-heaving Buoys, or Articulating Floats.
  • the P80 is one of the few WEC-FWTs that self-orient but the structure used to accomplish the self-orientation — slack mooring (no tension leg secured to the seabed for added stabilization— is patentably distinct from the disclosure.
  • the P80 is further distinguished from the disclosure due to the use of trailing (aft) floats hinged near the SWL to produce substantial energy-reducing “back waves” rather than the fore-positioned floats, of the disclosure, which are hinged substantially below the SWL (so that they move concurrently both upwardly and aft-ward on each wave crest), with concave float back walls to prevent generation of energy-robbing “back-waves”.
  • the WEC has a float 4 partially submerged below the Still Water Line (SWL) 18.
  • the float is connected by at least one swing or drive arm 51 to a pivot point or rotational axis or axel 52 that provides a rotational input into an electric generator or other power take-off (PTO) device 15 to produce useful energy or work.
  • PTO 15 is integral with, or affixed to, a substantially vertical spar frame (designated concurrently as 20, 109, 100) (top to bottom, respectively), which spar frame together with its lower drag plates (designated concurrently as 32, 33, 102), and their entrained seawater mass plus gravity weight 21 provide at least a portion of the WEC’s second body reaction mass.
  • Line 120 provides an optional slack secondary mooring line that prevents the WEC from rotating a complete 360° around submerged mooring ball 112 and wrapping around power and communications cables 114.
  • All WECs require a reaction mass or second body to resist the wave-force- induced force against, and motion of, the at least one primary or first body to do work or capture energy (work or energy capture equals force times distance or torque times rotation angle).
  • work or energy capture equals force times distance or torque times rotation angle.
  • the WEC second body reaction mass can be provided by one or more of the WEC bodies, such as massive platforms, barges, or rafts
  • these high-mass or high- horizontal-plane surface area reaction bodies require large quantities of steel, concrete or gravity mass ballast, which results in high WEC capital expense per unit output (CapEx/MW).
  • Using seawater as ballast in tanks or seawater entrained with drag plates attached to WEC reaction bodies is somewhat less expensive.
  • the WEC embodiment shown in FIG. 3 uses the seabed as a reaction mass to supplement the second body mass to stabilize the second body frame or base against undesirable motion.
  • Seabed 28 is connected to the frame or base secondary body by one or more tensioned cables 110 or tensioned legs anchored at piling points 35 that maintain a buoyant mooring body or buoy 112, mounted on a substantially vertical mooring shaft 116, at a fixed depth.
  • a structural mooring beam 107 is rigidly attached to the mono-spar frame 100, 109, 108, 20 at connection point 119.
  • mooring beam 107 is structural, it or its connection at 119 can provide some flexibility to reduce the “snap” or shock loading on tensioned cable(s) 110 when a severe wave load applied against float 4 and resisted by power generator 15 applies an aftward pitching moment to the mono-spar frame or base 100, 108, 109, 20. This places a counter-clockwise moment on mooring beam 107 through mooring ball 112 and mooring spar 116 to tensioned mooring cable(s) 110. Shock or snap loads can also be reduced or dampened by placing a spring or damping member or link (not shown) at either end of, or along, the tensioned leg or cable 110.
  • shock or snap loads may be reduced or dampened by incorporating a shock-dampening connection (not shown) at mooring- beam-to-frame connection point 119.
  • Routing of the power export and communications/control cables 114 goes from the PTO 15 housing, to and along mooring beam 107, down tensioned cable 110, through seabed attachment means 35, along seabed 28 and back to shore.
  • FIG. 3 shows a mono-spar frame, alternatively, two mooring beams
  • each like mooring beam 107) also can be rigidly mounted at 119 to a twin spar frame (as shown in FIG.1 of US Pat. Apl. Ser. No. 16/153,688) and converge at, or before, submerged mooring float 112.
  • a twin spar frame as shown in FIG.1 of US Pat. Apl. Ser. No. 16/153,688
  • float 4 When vertical (heave) and lateral (surge) wave forces from each oncoming wave crest both lift upwardly and rotate rearwardly, respectively, float 4, such rotation is resisted by the damping torque applied by PTO 15 within, or affixed to, spar frame 100 (lower section), and 20 (upper section).
  • Frame section 109 which can be located above (as shown) or below (not shown) generator 15, provides supplemental frame or base flotation.
  • Horizontal drag plate 32 with vertical surface 33 limits the upward vertical displacement of PTO pivot point or axis 52, which displacement also reduces the relative rotation (and energy capture) between drive arm 51 and PTO 15.
  • Chamber 24 can hold additional seawater ballast while plate 21 provides additional solid ballast mass, if needed.
  • the upward vertical displacement forces imparted on Frame 100 and 20 and on PTO input pivot point 52, when wave heave (vertical) forces are applied against float 4, are significantly reduced, or even eliminated, by the counter-clockwise moment about mooring buoy 112 provided by the concurrent lateral wave forces applied against float 4 front face 1 and transmitted through, and resisted by, PTO 15.
  • connection between lateral beam 107 and mooring buoy 112 can be hinged to allow vertical plane pivoting or hinging (not shown).
  • Slack secondary aft mooring line 120 can be utilized to prevent the WEC device from completely circling mooring buoy 112 which would either wrap power export and communications cables 114 or require slip ring electrical connections.
  • FIG. 3 shows a motion-stabilized WEC base or first reaction body, like use of mooring beam 107, mooring buoy 112, and at least one seabed-affixed tensioned member 110, applies motion stabilization of other buoyant surface or semi-submerged bodies including FWT bases or other platforms. Furthermore, while FIG. 3 shows a motion-stabilized WEC base or first reaction body, like use of mooring beam 107, mooring buoy 112, and at least one seabed-affixed tensioned member 110, applies motion stabilization of other buoyant surface or semi-submerged bodies including FWT bases or other platforms. Furthermore, while FIG. 3 shows a motion-stabilized WEC base or first reaction body, like use of mooring beam 107, mooring buoy 112, and at least one seabed-affixed tensioned member 110, applies motion stabilization of other buoyant surface or semi-submerged bodies including FWT bases or other platforms. Furthermore, while FIG. 3 shows a motion-stabilized WEC base or first reaction body, like use of moor
  • connection can be spring-like or at least one spring-like, energy- absorption or storage element can be located within 119, within mooring beam 107, or along the length of the at least one tensioned member 110, such that the rebound from prior wave-induced aft pitching, heaving, or lateral motion of first body 100, 20 is delayed or controlled until the next wave has applied at least a substantial portion of its pitching, heaving, and lateral forces against the first body. This rebound delay reduces or cancels the wave-induced base or reaction body motion of the prior wave.
  • FIGS. 4A and 4B a WEC, according to another aspect of the disclosure, is shown having the same features as the embodiment shown in FIG. 3, including the rigid vertical-spar-frame-to-mooring-beam connection at junction 119, but with horizonal drag plate 32 (in phantom) optionally eliminated.
  • FIGS. 4A and 4B illustrate how unwanted wave-heave-force-induced vertical displacement of PTO input axis 52 and unwanted counter-clockwise rotational (pitching) displacement about PTO input axis 52 can be substantially or totally eliminated without the use of large ballast mass or large drag- plate areas by optimizing the dimensions of lateral beam(s) 107 and vertical frame spar(s) 100
  • the disclosure utilizes an optimum ratio of MAH/MAS, by selecting both an optimum submerged depth of mooring buoy 112 and its pivot point 115 and an optimum mooring beam 107 length, which establishes the optimum lateral distance between the float 4 center of buoyancy 135 and the mooring buoy 112 pivot point 115 such that both the translation and pitch rotation of PTO input axis 52 is minimized throughout the average wave cycle for maximum wave-energy-capture efficiency.
  • the length of mooring beam 107 can be made adjustable to accommodate seasonal variations in average wave height and period. Changing the applied PTO 15 resistive or damping torque throughout each wave cycle will also change the heave and surge moments during each cycle.
  • a motion- stabilized buoyant base or frame serves as a common base or frame for both a WEC, and an FWT.
  • the WEC is similar in configuration those shown in FIGS. 3 and 4, as indicated by the reference characters shared in common.
  • FIG. 5 that differ from the features shown in FIGS. 3 and 4 include access hatch 36, which is relocated to an alternate position (not shown), and a wind turbine tower 163, which is placed on top of upper mono spar frame section 20.
  • Wind turbine nacelle 160 contains the wind turbine generator, gearbox (if utilized), power electronics, and turbine yaw (directional) mechanisms.
  • a wind turbine hub 161 has 3 turbine blades 162 and inputs rotational power to the generator or gearbox within nacelle 160.
  • Nacelle 160 can be oriented (swiveled in horizontal or vertical planes) independent of tower 163 although optionally-especially on smaller scale embodiments--a fixed nacelle-to-tower orientation can be used which allows the WEC to self-orient into combined oncoming wave fronts and wind directions which are usually, though not always, similar. Because the lateral wind forces applied against the wind turbine and its base, and the lateral forces applied against the WEC, may be from different directions and with different average forces, the self-orienting (weather-vaning) direction will be the vectored result of the wind and wave lateral forces.
  • an enlarged section 24 that has a larger cross-sectional area than the area of a main section of base section 100 that can be fully or partially filled with seawater or other ballasts (as per section 24 in FIG.3).
  • an optional circular substantially horizontal-plane drag plate 118 may be added below mooring buoy 112 to prevent downward displacement of buoy 112.
  • mooring buoy 112 can be an integral part of mooring beam 107. Beam 107, or attachments thereto, also can provide additional floatation (not shown) that supplements the floatation of mooring buoy 112.
  • FIG. 6 shows a side elevation view of the combined
  • the side walls of floats 4 have optional forward extensions 111 and aft extensions 150 each configured to reduce undesirable water flow (spillage) around the side edges of float 4.
  • Both the still water line (SWL) 18 and incoming waves 18’ above and below the SWL (dotted line) are shown.
  • the upper and lower extensions of mooring buoy shaft 116 which mooring buoy shaft 116 may be buoyant or non-buoyant, with secondary tensioned mooring lines or cables 117.
  • An extension of mooring spar 116 can reach, and be affixed to, the seabed (not shown).
  • an existing or purposed seabed-affixed pole, spar, piling or tower can serve the function of a seabed-affixed mooring spar 116.
  • Lower drag plate surfaces 32, 33, 102 can be reduced in size or totally eliminated by either increasing the submerged depth of the bottom of lower spar frame sections 100, 24 (which section 24 also serves as a seawater ballast tank), or by increasing the mass of gravity weight 21, which lengthens the natural pitch period (and moment of inertia) of the spar frame such that its forward pitch rebound (from the prior wave) continues as the float 4 is being both lifted and driven aftward by the next ensuing wave. This increases the relative motion between float and frame and resultant energy capture.
  • the flexural response of mooring beam 107 or its connection 119 to vertical spar frame 100 can be constructed such that the pitch rebound of the spar frame is dampened or delayed by the use of shock absorbers or energy-absorbing (visco elastic) materials in either the mooring spar 107 or its connection 119 with spar frame 100.
  • FIG. 7 shows an overhead plan view of the combined
  • FIGS. 5 and 6 floats 4 can rotate on their swing or drive arms 51 above or below mooring beam 107 without interference from the float sidewalls.
  • FIGS. 3, 4, 5, 6, and 7 illustrate that floats 4 can rotate a complete 360° without any mechanical interference. This is highly advantageous because it avoids severe sea, end-stop collisions and the damage associated with such collisions, which is a major limitation of most other WECs. If a rogue wave or severe seas lift float 4 beyond the point where its center of gravity is aft of the drive arm 51 to PTO 15 pivot point or axis or axel 52, then the PTO motor-generator simply rotates float 4 back to its proper forward operating position.
  • the preferred permanent magnet PTO generator(s) are also suitable for, and used as, motors, which avoids the need for an optional auxiliary motor drive.
  • the PTO motor-generator 15 can force floats 4 into a fully submerged position (where the float center-of-buoyancy 135 is substantially below the PTO pivot point or pivot axis or axel 52) where is the floats can be safely maintained in more docile waters below the wave troughs of even extreme 15-25 meter wave conditions.
  • Total submergence of floats 4 well below the wave troughs is further facilitated by the ability, in certain embodiments of the disclosure, to at least partially flood with seawater, at least a portion of the floats 4 interior and to use the relatively long float swing or drive arms 51 and the location of the drive arm to PTO pivot point 52 well below the SWL, combined with the ability to raise or lower the submerged depth of the base or frame 20, 109, 100, 24 by adding or removing base or frame seawater ballast from affixed or integral ballast- floatation chambers (upper and lower chambers 109 in FIG. 6 and 100 and 24 here and in FIG. 3).
  • the PTO motor-generator is utilized as a motor during a portion of almost every wave cycle to timely return float 4 and partially submerge it well into the next ensuing wave trough and maintain it there until wave buoyancy forces build to an a-optimal level before releasing the float to initiate each upward and aftward travel motion (power stroke).
  • PTO reactive power
  • FIG. 8 which is similar to FIG. 10 of US Application
  • FIG. 8 Shown in FIG. 8 is an optional shoaling plane 165 that precedes, and is substantially below, the WEC floats 4.
  • Shoaling plane 165 is securely affixed to mooring beam 107 by structural members 166 or alternatively may be affixed to the base or frame (not shown).
  • Part or all of the shoaling plate or plane 165 may be flat (not shown) or curvilinear (as shown) and may be substantially horizontal (not shown) or inclined upwardly (as shown).
  • the port-to-starboard width or beam of shoaling plane 165 may span most or all of the width of the combined WEC floats 4.
  • This shoaling plane protrudes deeper into the water column than the floats 4 to intercept wave energy that might otherwise pass below the WEC floats 4.
  • Shoaling plane 165 also increases wave height, while reducing wave length, which improves wave-energy-capture efficiency for WECs more effective at capturing wave energy from shorter wave lengths (which applies to almost all WECs).
  • FIG. 8 also describes the optional use of substantially horizontal drag plate or plane 168 or vertical drag plate or plane 169 located substantially aft of, and mounted or supported by, a beam 167 or structure extending laterally from frame or base 100. This is similar to the WEC shown in FIG. 7 of U.S. Pat. Apl. No. 16/153,688, but without an optional aft-tensioned mooring line 125. This aft location of drag plate 168 increases the moment arm and, therefore, drag plate effectiveness (vs the location of drag plate 32) against undesirable wave or wind-induced frame pitching.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • General Engineering & Computer Science (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
  • Wind Motors (AREA)

Abstract

La présente invention concerne un dispositif pour stabiliser, réduire ou commander la houle ou le pilonnement induit par le vent (vertical), la houle (latérale), ou le mouvement de tangage (roulis) d'une base flottante flottante ou semi-immergée, d'un radeau, d'une barge, d'une bouée ou d'un autre corps flottant tel que la base flottante d'un convertisseur d'énergie houlomotrice ou d'une base de turbine éolienne flottante. Le dispositif permet simultanément à la base flottante de s'auto-orienter ou à la girouette de maintenir sensiblement son orientation par rapport à la direction des vagues, des vents ou des rafales de vent venant en sens inverse. Le dispositif facilite également le maintien de la profondeur immergée ou de l'orientation verticale de la base flottante par rapport à la ligne d'eau fixe pour compenser les changements de profondeur de marée.
PCT/US2021/030135 2020-05-13 2021-04-30 Stabilisation de jambe de tension en porte-à-faux d'un convertisseur d'énergie houlomotrice flottant ou d'une base de turbine éolienne flottante WO2021231102A1 (fr)

Applications Claiming Priority (2)

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US15/930,752 2020-05-13
US15/930,752 US11131287B2 (en) 2012-05-08 2020-05-13 Cantilevered tension-leg stabilization of buoyant wave energy converter or floating wind turbine base

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4165306A4 (fr) * 2020-06-11 2024-07-10 Oddmund Vik Éolienne flottante

Citations (4)

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Publication number Priority date Publication date Assignee Title
US20150047544A1 (en) * 2012-05-01 2015-02-19 Exxonmobil Upstream Research Company Mooring Line Extension System
US20170022964A1 (en) * 2012-05-08 2017-01-26 Rohrer Technologies, Inc. Multi Mode Wave Energy Converter With Elongated Wave Front Parallel Float Having Integral Lower Shoaling Extension
US20180170488A1 (en) * 2014-05-27 2018-06-21 Esteyco S.A.P. Floating structure for wind turbine and method of intalling same
US20190040840A1 (en) * 2012-05-08 2019-02-07 Rohrer Technologies, Inc. High capture efficiency wave energy converter withimproved heave, surge and pitch stability

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150047544A1 (en) * 2012-05-01 2015-02-19 Exxonmobil Upstream Research Company Mooring Line Extension System
US20170022964A1 (en) * 2012-05-08 2017-01-26 Rohrer Technologies, Inc. Multi Mode Wave Energy Converter With Elongated Wave Front Parallel Float Having Integral Lower Shoaling Extension
US20190040840A1 (en) * 2012-05-08 2019-02-07 Rohrer Technologies, Inc. High capture efficiency wave energy converter withimproved heave, surge and pitch stability
US20180170488A1 (en) * 2014-05-27 2018-06-21 Esteyco S.A.P. Floating structure for wind turbine and method of intalling same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4165306A4 (fr) * 2020-06-11 2024-07-10 Oddmund Vik Éolienne flottante

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