US20100310376A1

US20100310376A1 - Hydrokinetic Energy Transfer Device and Method

Info

Publication number: US20100310376A1
Application number: US12/797,268
Authority: US
Inventors: Robert C. Houvener; Robert Edward Doyle; Tyler Nathaniel Doyle
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-06-09
Filing date: 2010-06-09
Publication date: 2010-12-09
Also published as: WO2010144567A1

Abstract

A hydro or aero kinetic energy device (100) includes a hydrofoil-shaped blade and rotor system (11) made from composite and membrane flexible materials with an innovative system design to create a large, but relatively light-weight hydrokinetic turbine that achieves disruptively low deployment cost and low Cost of Electricity (COE), in high volumetric flow rate, low velocity (1-3 m/s) marine or air currents. The system (100) continually senses the current (12, 14) at the deployment site and based on the current profile, adjusts the pitch of the blades in real-time, thereby leveling out the forces on the turbine rotor. The hydrokinetic energy device turbine (100) may be assembled onshore, on the way to the deployment site or at the deployment site Further, be turbine may include a remote control receiver mechanism (77), that allows an operator to remotely controlled the maneuvering and other aspects of the turbine (100) during deployment, operation and maintenance.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application Nos. 61/185,463 Filed on Jun. 9, 2009 and 61/325,518 filed on Apr. 19, 2010 both entitled “Hydrokinetic Energy Transfer Device and Method”, both of which are incorporated fully herein by reference.

TECHNICAL FIELD

The present invention relates to hydrokinetic energy and more particularly, relates to a device that allows the efficient capture of energy from fluid in motion, especially slow flowing fluids and to a device having an innovative blade system and design that utilizes high-strength and flexible composite materials in its construction, all of which features allow the device to be easily and innovatively deployed in position and placed in service.

BACKGROUND INFORMATION

Hydrokinetic power or energy utilizes the natural flow of water (or in the case of air this would be aerokinetic energy, such as wind turbines) such as tidal water, rivers, ocean currents, etc., to generate electricity. Hydrokinetic energy does not involve creating “head” utilizing dams or other water flow blocking structures but rather, involves extracting energy from very low velocity flows. Hydrokinetic power is therefore very ecologically friendly.
All the various configurations of hydrokinetic energy capture devices in the prior art suffer from one or more major flaws. First of all, efficient systems have been of very small design that do not scale well to a larger design. Those larger designs that have been tried are inefficient with a very high cost per kilowatt hour and inefficient use of the flow resource. All systems have suffered from difficult installation challenges. Moreover, most of the prior art systems need a relatively fast current (approximately 3 m/s) to be semi-viable.
Accordingly, given the cost of the prior art devices, their inefficiency and the cost of installing the devices, the energy they can extract from the fluid motion and later use for purposes such as electricity generation is not cost competitive with other methods of extracting energy and utilizing it for purposes such as electricity generation.
For example, a coal fired power plant has a cost of electricity (COE) of around 4-5 cents per kilowatt hour, whereas the best hydrokinetic device has a COE in the 15-20 cents range. At this point, no renewable power source, which can scale to industrial power levels (wind, solar, geothermal, etc.), has shown that it can match the COE of current methods of generating electricity by extracting energy from fossil fuels.
One key problem in designing a viable large hydrokinetic turbine is that the forces on the various cross sectional areas of the rotor vary based on local hydrodynamic conditions. For example, a 50 meter turbine may see a higher velocity of current flow at the top of its revolution, than it does at the bottom, as the water current can vary markedly over such distances in the water column. This variation in water current sets up forces that since unbalanced, can destroy a turbine and dramatically drive the cost of building one that can survive this set of forces utilizing a brute force approach.
Using the Electric Power Research Institute's (EPRI) energy conversion methodology, the instantaneous power that can be generated from flowing water by an underwater, hydrokinetic turbine is given by
P_{hydrokinetic-turbine}=η_w-w0.5 pAU³ equation (1)
where P is power in [W], A is the cross-sectional area of flow intercepted by the device, i.e. the area swept by the turbine rotor in [m²], p is the water density (1,000 kg/m³for freshwater and 1,025 kg/m³for seawater), U is current speed in [m/s] and _w-wis the “water-to-wire” efficiency, the product of all system efficiencies (rotor coefficient of performance, gearbox/generator efficiencies). There are other factors such as current velocity variation with depth, turbulence, etc—but this is the fundamental driving equation for today's systems.
Most prior art hydrokinetic systems are optimizing for U, the current speed, i.e., they are designing heavy, armored systems to be deployed in very fast 3+m/s flows, which are a tiny fraction of the current flows in the world. What is necessary, therefore, is a design that is optimized for both A and U, i.e. design scalability to enable increased swept area so that it can cost-effectively utilize slower, less violent and much more predominant current flows.
Accordingly, what is needed is a low cost approach to Hydrokinetic power that scales from a few Kw to 100's of Mw per system and due to its inherent efficiency at extracting energy from fluid motion, enables the extraction of energy from renewable sources, with no carbon footprint, at COE's that are at parity or better than the COE of coal, the lowest current COE generation method.

SUMMARY

The present invention combines a novel, cost-effective hydrofoil-shaped blade and rotor system made from composite and membrane flexible materials with an innovative system design to create a large, but relatively light-weight hydrokinetic turbine that achieves disruptively low deployment cost and low Cost of Electricity (COE), in high volumetric flow rate, low velocity (1-3 m/s) marine currents. The use of flexible materials and composites in the hybrid blade design enables low cost and scalable blades. The light weight system design enables a 4:1 reduction is system capital cost versus the armor plated units that are going after 3+ meters per second flow rates. Such a system dramatically opens up the scope of large, low velocity currents world-wide that are viable for use in cost competitive hydrokinetic generation in ocean and tidal currents and potentially rivers.
The present invention solves the problem of uneven forces on the turbine blades, thereby enabling large turbines, by sensing the water current and adjusting the pitch of the blades in real-time, thereby leveling out the forces on the turbine rotor and enabling a much lower cost and more scalable rotor. This automated control is accomplished by continually sensing the current via devices such as Acoustic Doppler Current Profilers (ADCP's) located upstream from the turbine rotor and based on the current profile, increasing or decreasing the pitch of the blade, with every revolution, in the area of the rotor that needs to compensate for the varying current. This control loop can not only adjust for the overall current changing, but by the use of a swashplate or similar device and control infrastructure, can adjust the pitch of the rotor blades at any point in the rotation, so as to compensate for the current in that exact area of the rotation where needed.
Moreover, the present invention combines a novel, cost-effective hydrofoil-shaped blade and rotor system made from composite and membrane flexible materials with an innovative system design to create a large, but relatively light-weight hydrokinetic turbine that achieves disruptively low deployment cost and low Cost of Electricity (COE), in high volumetric flow rate, low velocity (1-3 m/s) marine currents.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:

FIG. 1 is a schematic diagram of one embodiment of the kinetic energy generating device in accordance with the present invention;

FIG. 2 is a schematic diagram of another embodiment of the kinetic energy generating device according to the invention;

FIG. 3 is a schematic diagram of yet another embodiment of the kinetic energy generating device of the invention;

FIG. 4 is a schematic diagram of a pedestal mounted embodiment of the kinetic energy generating device of the present invention;

FIG. 5 is a schematic diagram of another pedestal mounted embodiment of the kinetic energy generating device of the present invention;

FIG. 6 is a schematic diagram of yet another embodiment of the kinetic energy generating device according to the teachings of the present invention;

FIG. 7 is an illustration of the rotor blade design of the kinetic energy generating device, according to one aspect of the present invention;

FIG. 8 is a close-up illustration of one rotor blade in accordance with one aspect of the present invention;

FIG. 9 is a schematic diagram illustrating a number of kinetic energy generating devices was input current is modified by one or more current altering devices mounted upstream from the kinetic energy generating devices;

FIG. 10 is an illustration of multiple deployment sites of a number of kinetic energy generating devices wherein the operation of one kinetic energy generating device is controlled or effect at by one or more sensors located at the deployment sites of one or more other kinetic energy generating devices;

FIG. 11 is a schematic diagram of yet another embodiment of a kinetic energy generating device in accordance with the present invention;

FIG. 12 is a schematic diagram of another embodiment of the kinetic energy generating device in accordance with the invention;

FIG. 12 A. is a schematic diagram of another alternative embodiment of the kinetic energy generating device of the invention;

FIG. 13 is a schematic diagram of yet another alternative embodiment of a kinetic energy generating device in accordance with the teachings of the invention; and

FIG. 13 a is a schematic diagram of another embodiment of a kinetic energy generating device in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show one embodiment of the hydrokinetic device 100 of the present invention which includes a turbine body 74, to which is attached a turbine rotor 11. Also attached to the turbine body 74 is a hydrofoil 16 with or without ailerons 28 which serve to stabilize the hydrokinetic device 100 as will be explained in greater detail below. Similarly, weighted ballast 18 may also be provided to orient the hydrokinetic device 100 and a current in a proper and desired orientation. The turbine body may include one or more ballast tanks 20, 22.
The turbine body 74 is a fully submergible pressure vessel that contains separate chambers, providing airtight internal environments that contain and allow the use of off-the-shelf components such as a generator 13, swashplate 10 and remote control circuitry 77, in addition to ballast tanks or compartments. The turbine 74 is large enough for humans to enter through a water tight hatch 75 and occupy the central region of the turbine 74 where the generator, drivetrain, and electromechanical devices are, for maintenance purposes (much like a generator room at the top of an off shore wind turbine). It is anticipated that humans would enter the hatch 75 after the device is surfaced, but it could be done at depth under water via an air lock from a small submersible which could dock with the turbine body 74.
The turbine body 74 is attached to a tether 21 via a cable 27. The turbine 74 maintains its altitude under water by pumping water in and out of ballast tanks 20, 22 and optionally 18, which compresses the air in the chambers and thereby increases or decreases the buoyancy of the turbine body 74.
Pitch control for the turbine 74 is provided by varying the amount of ballast in the fore and aft tanks 20, 22 thereby providing more or less lift in the front or rear of the turbine 74. Since the turbine rotor 11 imparts a torque on the rest of the turbine via the body 74, the hydro foil 16 provides lift, combined with the ailerons 28 which provide anti-roll and gravity weight ballast 18, providing opposing forces to the turbine body 74 to prevent it from rotating and to maintain altitude.
As the current or flow 30 increases, the lift provided by the hydrofoil 16 also increases, counteracting the tendency of the turbine to want to reduce its altitude due to the forces on the tether 21. Utilizing the hydrofoil 16 dramatically reduces the amount of weight needed in the ballast 18 for a given amount of anti-torque (anti-roll) needed, saving on the expense of gravity ballast materials, device structural cost and making deployment less costly. Support structures 24, 26 connect the hydrofoil 16 and ballast 18 to the turbine body 74, in a rigid manner, thereby creating a lever arm, which enhances the anti-rotation capability of the ballast and hydrofoil. The simple ballast and hydrofoil controls, much like that found on a modern sub, makes deployment, retrieval, flow alignment optimization, and storm protection much easier. In addition, these controls keep the device 100 below surface traffic in open ocean and deep tidal applications.
An additional feature of the present invention is a remote control receiver mechanism 77 that allows an operator to remotely control the maneuvering and other aspects of the turbine 100 during deployment, operation and maintenance. For example, an operator could remotely control the turbine's direction of travel, depth etc while being towed/positioned by a tug for installation; control deployment of the turbine 100 once at the deployment site; and control retrieval of the turbine 100 for repositioning or servicing. The remote control of the turbine 100 would be done via a laptop type computer or similar device, as is well known in the art, while communication would be via RF, hardwire, acoustic modem or similar communications 79, from the laptop or other device (not shown) to the on-board turbine main controller 77 which can be connected to all the movable, programmable, changeable, etc. elements of the turbine 100. This enables the device 100 to be built modularly at global locations, assembled near the deployment site, dropped in the water via a pre-existing shipyard like land based crane and towed to the deployment site, with tether and umbilical cables attached mostly at the surface, or with ROV and no divers needed. This will cut deployment costs by 10-20× versus current methods thereby reducing the deployment costs for megawatt scale hydrokinetic turbines from many hundreds of thousands or low millions of dollars per Mw to tens of thousands to low hundreds of thousands per Mw.
For deployment, the hydrofoil support structures 24, 26 can fold up, thereby reducing the size of the turbine during transport, while keeping it structurally intact for ease of final assembly at the deployment site. In one embodiment, the tether 21 and power cable 23 would be attached at the front of the torpedo shaped tube 74, in line with the axis of drag. An additional feature of the present invention is the ability to control when the rotor blades are attached to the rotor assembly 11. Final assembly or deployment of the blades may be made onshore, at a port, en-route to the deployment site, or at the deployment site as it may be too shallow or otherwise not be best to deploy/do final assembly of the blades to the rotor at one or more of these locations.
In a preferred embodiment, the power and tether cable(s) 23, 21 attach not only along the center of drag, but also mount behind the front of the torpedo-shaped tube 74, thereby enabling superior pitch control via the pitch control mechanisms. The cables 21, 23 utilize buoyancy control devices 25, such as those from Flotation Technologies of Maine, to reduce or eliminate the downward force of the cables 23, eliminating many of the problems that cable downward force creates for submarine hydrokinetic turbines which are disclosed in the prior art. In addition, at least the power cable 23 may be provided with a quick connect coupling 35, for use above or below the surface, such as those made by Teledyne ODI, allowing the device 100 to be easily and quickly deployed and retrieved.
In the preferred embodiment, the present invention includes a swashplate 10 located between the gearbox 13 and the rotor 15. The swashplate 10 allows a fixed control linkage(s) to operate on a set of rotor blades (not shown) attached to a rotating shaft. A swashplate is a device well known to those skilled in the art that is often typically used in a helicopter. The swashplate translates input via the helicopter flight controls into motion of the main rotor blades. Because the main rotor blades are spinning, the swashplate is used to transmit three of the pilot's commands from the non-rotating helicopter fuselage to the rotating rotor hub and main blades. By utilizing this method in the preferred embodiment, forces on the turbine can be made uniform, even during highly varying and non-uniform current flows and thereby enables large but relatively light weight and cost effective turbines.
For example, control of the rotor blades can be accomplished by 1) sampling the incoming current velocity in a 360 degree arc, forward of the turbine utilizing one or more sensors 12, 14, that measure water speed, density and other hydro/aerodynamic attributes can be used as inputs to the control loop; 2) determine if pitch needs to be adjusted anywhere in the arc of the rotor, based on differences in the current velocity from (1); 3) check to see where each blade is in the rotation cycle; then 4) adjust the pitch of the blade, as needed, using swashplate 10 to keep the load the same on all the blades; and 5) wait some period of time, then go back to (1).
In another embodiment of the hydrokinetic turbine as shown in FIG. 3, a flexible, rigid or a hybrid flexible/rigid foil 70 is connected to a shaft 72 that connects to the body 74. The foil 70 is of variable pitch, via an on-board control system and provides anti-torque to counteract the torque from the rotor (11). A similar foil 70 b can be part of the structure supporting the optional gravity ballast weight 18 and can similarly be automatically adjusted based on signals from on-board sensors and control systems (not shown), thereby enabling the turbine to maintain correct attitude at all times.
Although many of the control surfaces for the non-rotor components of the turbine are shown in various figures, in front (upstream) of the rotor 11, in some embodiments, some or all of these surfaces may be behind the rotor 11. In some embodiments outlined herein, the structure of the turbine body 74 can be a membrane structure, much like a rigid or semi-rigid airship.
In addition to the submarine-like free flying—tethered system deployment embodiments noted previously, the embodiment shown in FIG. 4 is especially well suited for tidal currents, where the flow of the current changes direction approximately 180 degrees regularly. In this embodiment, a gravity weight or semi-buoyant structure 92 is anchored in multiple locations to the seabed via cables 94, 96. The turbine body 74 is connected to the structure 92 via a shaft 90 and at the connection point 98, the turbine body 74 can swivel on the shaft 90, ending up in position 93, aligned with the opposite flow direction, such as for use in tidal flow areas.
With the turbine body 74, optional hydro-foil 99 and parts of shaft 90 being (semi) buoyant, the turbine maintains level flight in the water and counteracts torques created by the rotor. The body 74 optionally has a spring-like mechanism which forces the body to a position that is perpendicularly to the current when the current stops flowing. When the current restarts from the opposite direction, the drag from the rotor pulls the rotor 100 and body, down-stream. This process repeats itself, always returning the body to the same position during neutral tide and always allowing the rotor to be ‘pulled’ down-stream, where the current is coming from the left or the right in FIG. 4. This embodiment prevents electrical and other cables from wrapping themselves around the devices, as the device, due to mechanical stops in the swivel 98, can only rotate approximately 200 degrees of rotation on the swivel.
In an alternative embodiment, the device can swivel 360 degrees, but needs complex mechanisms such as slip rings to prevent cables from becoming entangled and failing, which adds to the cost of the turbine and creates maintenance problems. In some embodiments, enhanced flow is achieved into the rotor 100 via specially designed surfaces on the ballast systems 99, 92 such as the curved surface 91. This increased flow enables additional power to be generated by the turbine. In some embodiments, additional structure is provided down-stream of the rotor 100 to ensure there is sufficient drag to position the overall body 74 and rotor 100 for optimal energy conversion efficiency and to provide active control surfaces for maneuvering and stabilizing the turbine.
The embodiment shown in FIG. 4 has significant advantage over turbines that are fixed in place and accept current from either direction, since blades can only be optimized to accept flow from one direction. In the case of the fixed mount turbines that accept flow from both directions without swiveling into the flow, they suffer efficiency losses due to not being able to optimize the blades for uni-directional flow. The embodiment in FIG. 4 rotates into the flow automatically and hence overcomes this problem and only needs to accommodate flow hitting the blades from one direction, even though the flow can come from multiple directions during given time periods, such as in tidal current flows. This enables the embodiment in FIG. 4 to achieve significantly higher hydrodynamic efficiency and hence power output for a give rotor diameter and flow velocity, versus the fixed mount turbines that accept flow from both directions.
The embodiment shown in FIG. 12 is similar to that of FIG. 4, except that the turbine rotor 100 is actually up stream of the swivel 98, thereby reducing or eliminating any turbulence from being generated in front of the rotor 100 by the turbine structure such as weathervane mount 90 impacting turbine efficiency. In order to enable the same ability as the embodiment in FIG. 4 to self align with the current flow, especially in tidal flows which change direction on a regular basis, this embodiment has an alignment fin/foil 95 which, due to induced drag from the current, pulls itself downstream of the turbine and aligns the turbine rotor 100 with the flow direction and provides active control surfaces for maneuvering and stabilizing the turbine.
FIG. 12 a illustrates some refinements on the design of FIG. 12. This design has a tail that not only allows for attitude control, but can simultaneously provide anti-torque for the rotor. This is used in advanced airships and subs for maneuvering, but has not been used in this manner before. Note that the tail fins are at 45 degrees from horizontal and vertical, which is an enabler for better axial control, including in the present case, anti-torque. This reduces the amount of ballast and hence cost and weight, while improving the ability to ‘steer’ the device during deployment and to point in into the flow during operations, improving energy conversion efficiency.
Both designs (tethered open ocean and swinging tidal) still have adjustable ballast tanks in both the body and the lower ballast (be it the large one for swivel or the smaller one for open ocean). The open ocean version still tethers from the nose.
As shown in FIG. 5, the same mechanisms described in FIG. 4 can be utilized in a system that is hard mounted to the seabed floor. Similarly, the same mechanisms can be utilized in other embodiments, such as mounting to the underside of a barge in a tidal area, with similar benefits achieved. The blades can also be utilized in applications such as wind turbines or even in propulsion applications where strength, weight, low rpm, noise reduction, large scalability and cost are important.
In FIG. 6 an embodiment of a rotor having a flexible blade turbine with a rigid leading edge blade 52 is shown. In this embodiment, the leading edge 56 of the blade 52 is made of a rigid material such as a fiberglass and carbon fiber composite, with the sail-like composite membrane 64 being utilized for the rest of the blade 52. The membrane 64 in the preferred embodiment is a composite membrane, consisting of one or more layers of materials such as Carbon, Vectran, Mylar, Teflon and other similar materials of the type utilized in the sailing and fabric building materials industries, those materials having embedded or added directional fibers, the direction of which is uniquely designed for the stresses of the turbine blade, as determined by computer modeling and designer experience.
Additional layers of the composite membrane 64 may be provided and utilized for rip stoppage, Ultra violet (UV) light blocking, load attachment reinforcement, anti-fouling, membrane bias and other non-primary load direction support and other necessary capabilities, in order to ensure a useful lifetime of multiple decades under water. This embodiment does significantly reduce the cost of the blades, but does create very significant concentration of torque at points in the blades such as where the rigid mast mounts to the rotor and where the spars mount to the leading edge of the blade, limiting the cost effectiveness and reliability of the design.
FIGS. 7 and 8 overcome the limitation of FIG. 6 by designing the mast 38 in the mid part of the blade, thereby creating a more balanced torque on the mast 38 from the spars 42 and membrane 40, and also imparting much less torque on the pitch control mechanism 10 for the blade and the base of the mast.
As shown in FIG. 7, this embodiment utilizes a center mast flexible blade design 30. As with the leading edge mast blade design in FIG. 6, the center mast blade design has cross sectional shapes that are oriented with a twist relative to the blade tip direction that varies from the top to the bottom 36 for optimal efficiency. The center mast design also utilizes battens, spars and/or ribs 42 to enable the maintenance of optimal membrane shape during loading. Most importantly, the shape of the blade shown in FIG. 7 is designed using a fully coupled Computational Fluid Dynamics/Finite Element Analysis model, which allows it to be built to a shape that forms an optimal ‘flying’ shape when put under load, thereby increasing the performance of the blade by many percent in efficiency when operating in its design current velocity range.
The center mast design significantly reduces the torque transmitted to the mast and from the mast to the pitch change mechanisms and blade mounting point, reducing the complexity and cost of the blades and increasing reliability and scalability of the blades and overall turbine. This is due to the torque from the leading and trailing portions of the blade fabric 40 canceling each other out to a significant degree within the blade structure, based upon the design. The membrane of FIG. 7, as with the membranes noted in other figures, utilizes similar materials construction, as noted in the description of FIG. 6 above.
The membrane can be broken up into individual panels 35, 37, 39 that are separate and distinct from each other and that are designed separate and distinct from each other, thereby making maintenance easier, segmenting the loading of the overall blade membrane into more manageable pieces, making deployment easier and reducing mounting hardware. In addition, panels 35, 37, 39 can be rolled onto a spindle or similar mechanism attached to or inside of the mast 38, which is especially useful when the blades are used in wind turbines, where the blades can get overloaded in high winds and by rolling up the membrane, the cross section of the blades can be made much lower, dramatically improving server weather survivability, while still allowing excellent low velocity wind performance when the membranes are deployed. This enables higher overall turbine generating efficiency and better return on investment.
FIG. 8 shows an embodiment in which some or all of the backside of the blade has a membrane 140 covering it forming a two sided airfoil instead of a thin airfoil. Since the tip of the blade travels at a much higher speed relative to the water than the root of the blade, creating a two sided foil for some portion of the blade can increase the efficiency of the blade. This design allows for the optimal use of materials to gain efficiency, without using excess materials which does not have a good cost/benefit trade off. FIG. 8 also shows a blade tip cap 145, which increases the efficiency of the blade, by preventing the loss of lift off the end of the blade during operation.
The approach disclosed herein is to provide a turbine with flexible blades, similar to rig and sails used to propel sailing yachts/ships weighing 700 tons up to 20 knots. By utilizing fully coupled CFD and FEA simulation and optimization system, the blades can be designed such that they will have optimal shape when loaded by the known flow. This loaded shape is known as “the flying shape” in sails. Designing for the flying allows the important blade design parameters such as section chord, camber and twist to be optimized for the deformation expected in the structure rather than designing for an unloaded condition and then trying to minimize the loss in performance due to deformation of structure mainly by trying to limit the deformation. Such a structure saves tremendously in material and manufacturing costs as well as allows the resulting blade to be modular in design, resulting in easier transport and future maintenance.
The present invention discloses an approach that defines three regions of the blades on the turbine, based on Reynolds-number regimes, and individually optimizes the construction of those regions based on a heretofore un-available cost/performance trade-off The tip of the blade 145, where higher Reynolds numbers occur, is a highly efficient semi-flexible composite hydrofoil structure; while the mid region 147 where moderate Reynolds numbers occur, is a composite frame with dual sided flexible membrane made of new, much stronger, thicker materials such as ePTFE (expanded polytetrafluorethylene), as well as custom embedded carbon and Vectran fiber layouts. These materials have been used in building construction and marine industries for over a decade. One of the strongest and most durable of these materials, Vectran, has tensile strength of over 1400 pounds per linear inch and can withstand approximately 50,000 psi of stress. In addition, these materials have excellent anti-fouling properties and are guaranteed for 15-25 years, in very hostile environments, including salt water. The design of the proposed hydrokinetic power system, regardless of scale, will require special attention relative to design, assembly/installation requirements and use of materials offering protection against corrosive operating environments (e.g. sea water). Finally, the root of the blade 149, where low Reynolds numbers occur, is a more ‘sail-like’ composite frame, with a single sided foil. The blade utilizes a single composite ‘mast’.
Once the turbine rotor is assembled, the relatively lightweight and flexible blades can be easily attached and/or replaced when maintenance is required, much like attaching a sail on a large sail boat. In addition, individual panels on blades can be changed in the field. Blade characteristics can be easily optimized by site, enabling maximum efficiency and power generation for any site conditions. This is a significant enabling breakthrough, as the ability to design to the ‘flying’ shape is important in order to achieve the cost and performance it seeks over wide current velocity ranges. Previous industry attempts at using fully coupled CFD/FEA simulation models have not been overly successful due to excessive computational cost and stringent requirements imposed on the CFD and FEA computational grids to ensure numerical stability of the force coupling schemes. The coupling scheme employed gets around this difficulty by utilizing an iterative force coupling stabilization loop thereby reducing the computational requirements on the combined system and reducing the complexity involved in transmitting forces between the fluid dynamic (CFD) and structural (FEA) computational meshes.
Even with very large swept areas, approaching 100 m in diameter, this design can be built modularly, assembled at a port near to the deployment site, deployed in the water via on-shore cranes, towed to its deployment site, attached to its mooring lines/umbilical, and submerged to its deployment depth; all with ubiquitous and low cost off-shore oil and gas support vessels. For support, again the device can be re-surfaced by adjusting ballast and control surfaces, again necessitating only low cost (low $1,000's/day), off-shore work boats, leveraged from oil and gas support industries. This is in stark contrast to existing hydrokinetic systems, which require highly specialized, scarce and extremely expensive (some greater than $500,000/day) support vessels for deployment and maintenance. Deployment without any structure at or near the surface significantly reduces the negative effects of wave action, and eliminates surface-visual pollution.
In one system deployment embodiment, flow diverters 110-113, FIG. 9, are strategically placed near the turbines 114-118 in a turbine farm. As shown in FIG. 9, if placed upstream, these diverters increase the velocity of the water going between them (say 110 and 111) and direct the flow of current into the downstream turbines (in this case turbine 118), increasing the velocity of water hitting the rotor and hence increasing the output of the turbine. Like portions of the turbine, significant portions of the flow diverters can be made out of membrane structures, tethered to the seabed, providing a cost effective velocity acceleration mechanism that is easily deployed. An increase of just 25% in the velocity of the current hitting the rotor 100, will double the amount of power that is derived from the turbine. The diverters 110-113 can be placed upstream as well as within the overall turbine farm.
As shown in FIG. 10, the combination of energy extraction devices 132, 134, 136 in the form of hydrokinetic or Ocean Thermal Energy Conversion (OTEC) devices, combined with networked ocean sensors 130 and control station(s) 138 enable a energy extraction control loop in which the amount of heat energy going toward the polar caps can be regulated in semi-real-time. By measuring the amount of heat energy reaching the sensors 130, more or less energy can be extracted by turning on/off energy extraction devices in the major global current flows. This not only can reduce global warming impacts, but can enable the optimal level of energy extraction from global current flows, while ensuring damage does not occur from over-extracting energy. In the preferred embodiment, existing as well as purpose built ocean sensors would be utilized to monitor the energy dynamics and adjust energy extraction accordingly. In addition, algorithms can be utilized to determine the optimal extraction methodology, be it extracting thermal energy via OTEC or kinetic energy via hydrokinetic turbines. In addition, the optimal area to extract the energy from, to get the desired global effect, can be determined by mining the sensor data and adjusting the control loop. This embodiment, the Global Energy Management System (GEMS) can optimize the overall thermo and kinetic energy flows of the global oceans.
Farms of turbines as disclosed herein can also be used to tap into large dispersed areas of low velocity tidal currents. Adjacent tidal farms, properly controlled, can provide continuous power to the grid without the typical interruptions suffered by conventional hydrokinetic tidal systems. As the ebb (tide) runs down the coast, adjacent systems that are not in ebb will still power the grid, delivering what is effectively base load power to the grid in coastal areas with high volume, low speed tidal current flows. In contrast, this cannot be achieved with present hydrokinetic turbines because they require very fast current flow, and the areas where these exist are far too sparse to enable turning periodic flow into baseload capability.
In addition to utilizing the flexible membrane systems to reduce the cost and complexity of blade and other structural elements, membranes can also be utilized to provide a highly cost effective ducting system 150,152 as shown in FIG. 11. In preferred embodiments, the ducts can utilize adjustable fins for anti-torque purposes, either as inflatable duct structures 154 or as structures utilizing the main duct membrane itself with spars for shape maintenance 156. By moving the spars in 156, the shape of the fin can be manipulated and pitch can be changed dynamically. The mount point for the tether 158 can optimally be in line with the axis of rotation, although in some embodiments, other mount points are advantageous.
As shown in FIG. 13 a, this design has a tail that not only allows for attitude control, but can simultaneously provide anti-torque for the rotor. This is used in advanced airships and subs for maneuvering, but has not been used in this manner before. An embodiment with thrusters 170 is contemplated for attitude control and anti-torque, as well as possibly station keeping if the current dies down.
Accordingly, the present invention solves numerous deficiencies in the prior art providing a novel and non-obvious hydrokinetic or aero kinetic generating device that makes use of flexible materials and composites in the hybrid blade design enabling low cost and scalable blades and device itself which allows a significant reduction in the system capital costs and deployment costs dramatically opening up the scope of large, low velocity currents worldwide for use and cost competitive hydrokinetic (or aero kinetic) generation in ocean, tidal currents and rivers.
The present invention is not intended to be limited to a device or method which must satisfy one or more of any stated or implied objects or features of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the allowed claims and their legal equivalents.

Claims

1. A rotor blade, comprising:

a rotor blade having a tip region, a base region and a middle region disposed between and adjacent said tip and base regions, said tip region consisting of a semi-rigid material, said middle region consisting of a frame covered by composite flexible material, said frame covered by composite flexible material according to a first construction, said base region consisting of a frame covered by a composite flexible material according to a second construction different from said first construction of said middle region.

2. The rotor blade of claim 1, wherein said tip region is made of a relatively hard material.

3. The rotor blade of claim 1, wherein said first construction of said middle region of said rotor blade includes a frame having a first side and a second side, and wherein said composite flexible material is disposed on both said first and second sides of said frame.

4. The rotor blade of claim 1, wherein said second construction of said base region of said rotor blade includes a frame having a first side and a second side, and wherein said composite flexible material is disposed on only one of said first and second sides of said frame.

5. (canceled)

6. (canceled)

7. The kinetic energy generating device of claim 9, wherein said rotor blade receiving device includes

a rotor blade pitch control device, configured for receiving said plurality of rotor blades and for individually and independently controlling a pitch of each of said plurality of rotor blades attached to the pitch control device.

8. (canceled)

9. A kinetic energy generating device comprising:

a turbine body;

a rotor assembly attached to said turbine body, said rotor assembly including a rotor blade receiving device, configured for receiving a plurality of rotor blades; and

a plurality of rotor blades, each of said plurality of rotor blades removably attachable to said rotor blade receiving device and having a tip region, and a base-middle region disposed adjacent said tip region, said tip region consisting of a semi rigid material, and said base-middle region consisting of a composite flexible material.

10. The kinetic energy generating device of claim 9, wherein said turbine body further includes one or more of an altitude, depth, attitude and/or positioning device, and wherein said turbine body further includes a remote control signal receiving mechanism, coupled to at least one of said one or more altitude, depth, attitude and/or positioning device, for receiving remote control signals from an operator device, said remote control signals configured for controlling one or more of said altitude, depth, attitude and/or positioning device, said remote control receiving mechanism configured for providing said received remote control signals to an appropriate one or more of said altitude, depth, attitude and/or positioning device.

11. The kinetic energy generating device of claim 9, wherein each of said plurality of rotor blades has a tip region, a base region and a middle region disposed between and adjacent said tip and base regions, said tip region consisting of a semi-rigid material, said middle region consisting of a frame covered by composite flexible material, said frame covered by composite flexible material according to a first construction, said base region consisting of a frame covered by a composite flexible material according to a second construction different from said first construction of said middle region.

12. The kinetic energy generating device of claim 9, further including one or more sensors on said turbine body, upstream of the rotor, said one or more sensors configured for measuring, in real-time, a current hitting the rotor in and responsive to said measuring, for providing a signal to a control device causing said control device to provide one or more of an attitude control signal and a rotor blade pitch change signal, for improving the efficiency and reducing destructively uneven forces on said turbine.

13. The kinetic energy generating device of claim 9, further including one or more cables coupled to said turbine body, said one or more cables including one or more cable buoyancy control devices disposed on the one or more cables, said one or more cable buoyancy control devices configured to eliminate an impact of said one or more cables on the turbine.

14. A method of deploying a hydrokinetic turbine, said method comprising the acts of:

providing a hydrokinetic turbine comprising a turbine body and a rotor assembly, coupled to said turbine body, said rotor assembly configured for accepting a plurality of rotor blades;

moving said hydrokinetic turbine proximate a location at which said hydrokinetic turbine is to be deployed;

assembling said plurality of rotor blades to said rotor assembly at a location selected from the group of locations consisting of onshore, at a port, while said hydrokinetic turbine is being moved toward a deployment location, and once said hydrokinetic turbine is act said deployment location;

placing said hydrokinetic turbine in water at said deployment location; and

causing said hydrokinetic turbine to become located below a surface of said water at said deployment location.

15. The method of claim 14, wherein said hydrokinetic turbine includes one or more of an altitude, depth, attitude and/or positioning device, and wherein said turbine body further includes a remote control signal receiving mechanism, coupled to at least one of said one or more altitude, depth, attitude and/or positioning device, for receiving remote control signals from an operator device, said remote control signals configured for controlling one or more of said altitude, depth, attitude and/or positioning device, said remote control receiving mechanism configured for providing said received remote control signals to an appropriate one or more of said altitude, depth, attitude and/or positioning device; and

wherein said act of causing said hydrokinetic turbine to become located below a surface of said water at said deployment location includes providing remote control signals from an operator device, said remote control signals configured for controlling one or more of said altitude, depth, attitude and/or positioning device located within said hydrokinetic turbine.