Abstract:
A turbine integrated within a hydrofoil extracts energy from a free-flowing motive fluid. In the preferred embodiment, the turbine is of the crossflow variety with runner blades coaxial to the width of the hydrofoil. The foremost edge of the hydrofoil comprises a slot covered by a continuously adjustable gate for controlling the overall drag imposed by the turbine. The hydrofoil mounts to a sailing vessel by means of a gimbal on a structure affixed to the hull, enabling the turbine to optimally respond to changes in direction of the free-flowing motive fluid and facilitating guidance and stability of the vessel.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of U.S. application Ser. No. 11/942,546, entitled “Turbine-Integrated Hydrofoil,” filed Nov. 19, 2007, which is a continuation of U.S. application Ser. No. 11/162,177, entitled “Turbine-Integrated Hydrofoil,” filed Aug. 31, 2005. The present application incorporates the above-cited patent application herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is generally in the field of power plants. More specifically, the present invention is in the field of hydrokinetic generators with means to adapt to changes in streamline direction and magnitude of a free-flowing motive fluid. Most importantly, the present invention maximizes net energy by utilizing a hydrokinetic generator mounted on a marine sailing vessel that also limits drag on the vessel in a controlled manner. 
       BACKGROUND 
       [0003]    Considering present humankind&#39;s primary source of energy, fossil fuel can diminish to the point of negligible net energy within this century; there exists a fundamental need for developing renewable and sustainable sources of energy including further exploitation of readily available known resources. More specifically, there exists a need for a novel approach to ensure least impact to environment and low civic infrastructure costs such that the energy investment return is most quickly realized. Utmost, to optimally exploit oceanic energy, which may be attained anywhere over approximately three quarters of the surface of the planet thus availing vast industrial growth potential, the main obstacle existing is the delivery from such an expansive source of energy. 
         [0004]    While many patents exist for harnessing energy from pneumatic and hydraulic sources, relatively few have considered a mobile structure to facilitate delivery of energy and maintenance and servicing of the structure. For instance, wind turbines mounted on abandoned off shore oil rigs, as well as both wind turbines and hydrokinetic turbines mounted on structures essentially resembling deep-sea buoys have begun to proliferate. These types of structures obviously do not adequately address delivery of energy considering their distance from the shore, the actual distribution center. These structures also impede maritime traffic and present maintenance difficulties especially in severe weather conditions. Another limitation of this prior art overcome by the present invention is that the density of water is approximately seven hundred seventy five times greater than air and thus a wind turbine must occupy an area seven hundred seventy five times greater than a hydrokinetic turbine in order to yield equivalent power given equal velocity of the motive fluids. The prior art structures utilizing hydrokinetic turbines yield power limited by the velocity of the motive fluid converted from wave motion alone. In contrast, a sailing vessel of limited drag may achieve velocities greater than the wind velocity thus illustrating one way in which the present invention optimally uses the advantages of combining hydraulic and pneumatic mediums. Even fewer patents so far have addressed the need to reduce drag caused by the mobile structure while engaged in the motive fluid. 
         [0005]    The reduction of drag, the combined exploitation of hydraulic and pneumatic energy mediums, and the integration into a singular mobile combined generation and delivery system with means to optimally respond in a controlled manner to changes in velocities of the media exemplify the patentable novelty the present invention holds over prior art. 
       SUMMARY 
       [0006]    The present invention achieves the goals of overcoming existing limitations of prior art oceanic hydrokinetic and pneumatic power generation systems foremost through integration into a singular generation and delivery system to extract power from free-flowing seawater while simultaneously exploiting wind energy. While prior art exists which functions in free-flowing bodies of water or wind, the novelty of this invention lies in its ability to respond and adapt to any change in the magnitude and direction of the streamlines of plural free-flowing motive fluids while controlling drag caused by moving in any direction within the mediums of wind and water. Through implementing a system to control vessel velocity given input parameters such as wind velocity, seawater current velocity, vessel mass and drag affecting actual velocity of the vessel, and feedback of generator output voltages; this enables the present invention to extract optimal energy from both pneumatic and hydrokinetic sources. Controlling the drag also facilitates maintaining overall stability and guidance of the vessel. 
         [0007]    Secondly, because developing an integrated generation and delivery system which optimally adapts to changes in both magnitude and direction of the streamlines of plural free-flowing motive fluids formed the basis of the guiding concepts of the present invention; this readily avails the present invention the applicability to any body of water anywhere. Thus, the present invention does not require a large scale of infrastructure and therefore greatly diminishes the environmental impact while attaining a positive net energy earlier upon implementation. 
         [0008]    Optimizing energy efficiency in the control of all processes including drag, ballast depth, vessel stability and velocity, and electrolysis of water in an integrated control loop positions the present invention as desirable for implementation in gathering energy for emerging power conveyance systems, especially hydrogen fuel and fuel cell technology. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a general perspective view of a vessel implementing an exemplary apparatus in accordance with a preferred embodiment of the present invention. 
           [0010]      FIG. 2  illustrates a perspective detailed view of a turbine-integrated hydrofoil according to the preferred embodiment of the present invention. 
           [0011]      FIG. 3  illustrates a bottom view of the gimbal mounting means along the mounting beam for the turbine-integrated hydrofoil in  FIG. 2  according to a preferred embodiment of the present invention. 
           [0012]      FIG. 4  illustrates a perspective cross-section view of two positions of the gate for the turbine or electrolyzer according to an embodiment of the present invention. 
           [0013]      FIG. 5  illustrates a perspective view along the axis of the rotor, a cross section of an impeller with runner blades within the turbine according to a preferred embodiment of the present invention. 
           [0014]      FIG. 6  illustrates a top-downward view of the outline of the hull and mounting of the vessel according to an alternate embodiment of the present invention. 
           [0015]      FIG. 7  represents a schematic view of a DC generator implementing switch mode field excitation directly coupled to the output shaft of the fluid coupler according to a preferred embodiment of the present invention. 
           [0016]      FIG. 8  illustrates the flowchart for control of the complete system according to a preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    The present invention is directed to a turbine-integrated hydrofoil for adaptively extracting energy from plural free-flowing motive fluids that continuously change direction and magnitude of flow. The following description contains specific information pertaining to various embodiments and implementations of the present invention. One skilled in the art will recognize that the present invention may be implemented in a manner different from that specifically depicted in the present specification. Furthermore, some of the specific details of the invention are not described in order to maintain brevity and to not obscure the invention. The specific details not described in the present specification are within the knowledge of a person of ordinary skills in the art. Obviously, some features of the present invention may be omitted or only partially implemented and remain well within the scope and spirit of the present invention. 
         [0018]    The following drawings and their accompanying detailed description are directed as merely exemplary embodiments of the invention. To maintain brevity, some other embodiments of the invention that use the principles of the present invention are specifically described but are not specifically illustrated by the present drawings, and are not meant to exhaustively depict all possible embodiments within the scope and spirit of the present invention. 
         [0019]      FIG. 1  illustrates a general perspective view of a vessel  100  implementing an exemplary apparatus in accordance with one preferred embodiment of the present invention.  FIG. 1  depicts three turbine-integrated hydrofoils  101  engaged in the direction of the vessel  100 . The present invention may implement any number of a plurality of turbine-integrated hydrofoils  101 . The turbine-integrated hydrofoils  101  couple to the vessel  100  through corresponding beams  105  affixed to the hull  102  of the vessel  100 .  FIG. 1  portrays a single hull  102  although implementation of a multi-hull structure does not constitute a substantial departure beyond the scope of the present invention. A design of adequate buoyancy of the turbine-integrated hydrofoil  101  may supersede the implementation of any hull whatsoever. Further description of means of buoyancy within the turbine-integrated hydrofoil  101  and of an alternate shape of the hull  102  follows in subsequent paragraphs,  FIG. 2 , and  FIG. 6 . The length of beam  105  may extend to varying distances from the vessel&#39;s center of gravity through variable extension means  104  depending upon the velocity and stability of the vessel  100 . The variable extension means  104  may vary in length through a controlled stabilizing locking motor mechanism not shown, or through a hydraulic piston-driven turbine system not shown. The hydraulic piston driven turbine system extracts supplemental energy from the tension and compression forces on the variable extension means  104  when drag varies from one hydrofoil  101  to the next during a vessel  100  stabilizing process engaging plural turbine-integrated hydrofoils  101 . The beam  105  terminates at the gimbal mounting means  103  further described in a subsequent paragraph and in  FIG. 3 . Below the waterline, the output fuel tank  106  affixes to the hull  102  through variable extension means  107  which varies the draft of the output fuel tank  106  by varying extension length depending upon vessel velocity and stability, and mass of the output fuel tank  106  affected by fullness thereby providing ballast. Sails  108  provide the ordinary means of extracting energy from pneumatic sources. Because the hydrofoils  101  mount upon a beam extension means  104  of variable length, the sails  108 , while not necessarily drawn to scale in  FIG. 1 , may significantly exceed the typical area of a sail for a vessel of a given hull size as depicted in  FIG. 1 . Furthermore, implementation of any area and material type for the sail  108  not explicitly addressed herein does not constitute a departure beyond the scope of the present invention. The mainmast  109  affixes the sail  108  employing means typically practiced in the art, though once again, due to the additional stabilizing effect provided by the hydrofoil mount beam variable extension means  104 , the mainmast  109  may significantly exceed the typical height of a mainmast  109  for a vessel of a given hull size as depicted in  FIG. 1 . A lightening rod  110  mounts atop the mainmast  109  in order to extract additional energy from electrical storm activity. Given a mainmast  109  extending to greater heights than typical mainmasts for a vessel of the depicted hull size, and also in order to extract optimal pneumatic and hydraulic energy the vessel  100  will plot a trajectory towards maximal weather conditions likely including electrical activity, the present invention thus extracts further energy through lightening strikes to the lightening rod  110 . 
         [0020]      FIG. 2  illustrates a detailed perspective view of the turbine-integrated hydrofoil  101 , which provides a fundamental and significant departure from prior art and considerable novelty in the present invention. The dashed line  200 - 201  represents the axis of rotation  216  of the entire assembly of the hydrofoil  101 . To minimize undesired mechanical oscillatory motion  216  that reduces efficiency and induces stress, the dashed line traverses through the center of gravity of the turbine-integrated hydrofoil. The rotation means  215  likely comprises circular bearings and serves two purposes. First, directly coupled through motor and locking means not shown, the rotation means  215  can adjust the angle of pitch of the hydrofoil  101  to optimize dynamic lift for variable vessel  100  velocities. Secondly, once the locking means not shown coupled to the rotation means  215  disengages, the motor not shown coupled to the rotation means  215  may operate as a generator extracting supplemental energy from rotational motion  216  caused by changes in direction of the free-flowing motive fluid. One of ordinary skill in the art will readily recognize the rotation means  215  forms one axis of a gimbal, a second axis formed by the gimbal mounting means  103  depicted in  FIG. 3  and described in a subsequent paragraph. The present invention thus adapts to any change in direction of the streamlines  202  of a free-flowing motive fluid. 
         [0021]      FIG. 2  further shows the streamline  202  of the free-flowing motive fluid entering the gate  204  of the turbine-integrated hydrofoil  101 , proceeding through the outline of the fluid coupler means  205 , and changing in pressure and velocity as indicated by the streamline  203  in the draft section of the turbine of different size and shape than the entering streamline  202 . In the preferred embodiment, the fluid coupler means  205  entails a cross-flow impeller design as depicted in  FIG. 5  and described in a subsequent paragraph. As the flow passes through the fluid coupler means  205 , it impinges upon the lower surface  206  of the draft section of the turbine whereupon the gate to the electrolyzer may be found. Both the turbine gate  204  and the electrolyzer gate on lower surface  206  are illustrated in detail in  FIG. 4 . The electrolyzer preferably sits in the area  209  between the lower surface  206  of the draft section of the turbine and the outer lower surface  208  of the hydrofoil  101  itself. One electrode  211  of plural electrodes and the electrolyzer membrane  210  are shown and further comprise temperature sensors not shown which in part determine the openness of the electrolyzer gate. By flowing from the input gate in area  209  through the exit gate in area  212 , the motive fluid of the turbine also serves as electrolyte as well as forced convection cooling fluid for the electrolyzer membrane  210  and electrodes  211 . The openness of the electrolyzer gate and the turbine gate  204  affects the overall drag of the hydrofoil  101 , and thus besides electrolyzer membrane  210  and electrode  211  temperature, the drag, stability, and velocity of the vessel  100  represent input variables into the control algorithm for opening the electrolyzer gate and turbine gate  204 . In the preferred embodiment, the anode electrode  211  is composed of, or plated with manganese dioxide to minimize the amount of sodium hypochloride, NaOCI, also known as sodium chloroxide or chlorine bleach that collects at the anode  211  while operating in salt water. Hydrogen gas output from the electrolyzer becomes sequestered in a storage tank  207  or in the area  213 . The hydrogen gas further enhances buoyancy of the overall hydrofoil  101 . Obviously, any change in position of gates or area that the electrolyzer occupies within the hydrofoil  101  in the preferred embodiment does not constitute a substantial departure beyond the scope of the invention. 
         [0022]    The remaining features depicted in  FIG. 2  include the external fins  214 , and the support brace  217  directly coupled to the main strut  218 . The main strut  218  directly couples to a rotating member  300  depicted in  FIG. 3 .  FIG. 3  illustrates the rotational direction  301  allowed by the rotating member  300  affixed to the gimbal mounting means  103 . As previously described for the primary axis, the rotating member  300  depicted in  FIG. 3  affixed to the gimbal mounting means  103  forms the second axis of a gimbal. The rotating member  300  likely comprises circular bearings and serves two purposes. First, directly coupled through motor and locking means not shown, the rotating member  300  can adjust the angle of attack of the hydrofoil  101  and thus with the external fins  214  behaving as the keel board of the vessel  100 , control guidance and stability of the vessel  100 . Secondly, once the locking means not shown coupled to the rotating member  300  disengages, the motor not shown coupled to the rotating member  300  may operate as a generator extracting supplemental energy from rotational motion  301  caused by changes in direction of the free-flowing motive fluid impinging on the external fins  214 . The present invention thus further adapts to any change in direction of the streamlines  202  of a free-flowing motive fluid. Let it further be known that given means to extract supplemental energy from the tension and compression forces on the variable extension means  104  and use of the external fins  214  and rotating member  300 , the utilization of the vessel  100  in a body of free-flowing motive fluid of constant direction may entirely obviate a sail  108  and mainmast  109 . 
         [0023]      FIG. 4  illustrates two positions of a suitable embodiment of a mechanism for the gate to the electrolyzer or the turbine itself. The left hand side of dashed line  400 - 401  portrays the view of the gate in a closed position while the right hand side of dashed line  400 - 401  portrays the view of the gate in the open position. The arrows  402 ,  403  indicate the streamline of either the free flowing motive fluid  202  impinging on the turbine-integrated hydrofoil  101  itself, or the motive fluid  203  passing the gate of the electrolyzer on the lower surface  206  in the draft section of the turbine. Arrow  402  implies flow passing unabated over the closed gate whereas arrow  403  implies partially diverting flow inward while passing over an open gate. The blades  404  of the gate rotate synchronously upon an axis  405  depending upon the required adjustment. Arrow  406  indicates a closed gate adjusting to a more open position while arrow  407  indicates an open gate adjusting to a more closed position.  FIG. 8  and subsequent paragraphs furnish further detail into the algorithm that determines the openness of each respective gate. While the gate mechanism presented in this specification likely provides adequate if not optimal functionality, the use of any other gating means not explicitly described herein does not constitute a substantial departure beyond the scope of the present invention. 
         [0024]      FIG. 5  illustrates a perspective view of a fluid coupler, a cross-flow impeller looking along the axis of the rotor within the turbine. Dashed line  200 - 201  indicates the axis of rotation as stated before and viewed in  FIG. 2  where the outline area of the fluid coupler  205  first became manifest. Here  FIG. 5  shows a cross-sectional view of the rotor  500  as motive fluid  202  passes over the plurality of runner blades  501  to finally exit as draft flow  203  after depositing most energy in the form of both impulse force impinging upon the blade  501  and reactive force when leaving the blade  501 . As this curved form of cross-flow impeller is well known within the public domain as derived from the Pelton water wheel concept for optimal energy extraction, the specification herein thus requires no further description. In light of the aforementioned, the modification of Pelton runner blades in the preferred embodiment is purely exemplary, illustrative and not restrictive. As previously stated, the fundamental goal of the present invention is to attain the highest possible net energy, in other words, highest return on investment in terms of energy; through implementing the simplest design. While the impeller herein presented likely provides optimal functionality, let it hereafter be known that any impeller, whether or not responsive to impulse and reaction forces, within a turbine-integrated hydrofoil responding to changes in direction and magnitude of the streamlines of a free-flowing motive fluid does not constitute a substantial departure beyond the scope of the present invention. 
         [0025]    This specification now refers to  FIG. 6 , a top-downward view of the outline of an alternate embodiment of the hull and mounting system. As previously stated, the vessel  100  may possess a single hull or a multiple hull structure, or no hull whatsoever given adequate buoyancy of the turbine-integrated hydrofoil  101 . The outline of the hull  102 , indicated by lines  600  in  FIG. 6  represents a most agile structure for maneuverability, guidance and adaptation to changes in direction of pneumatic and hydraulic motive fluids given the gimbal mounting means  103  previously described for the turbine-integrated hydrofoil  101 . The line  601  represents the keel board of the hull, mainly shown to clarify the view of the structure of the hull  102  in  FIG. 6 , which otherwise serves no practical purpose given the external fins  214  of the turbine-integrated hydrofoil  101  depicted in  FIG. 2 . Lines  602  and  603  represent alternate embodiments of the beams  105  and variable extension means  104  previously described. Line  603  thus represents a pinion member acting upon a rack gear in the middle of line  602  to increase or decrease the length of lines  602 . Increasing the length of any singular line  602  increases the area of the triangle  602  formed by plural lines  602 , thus moving the gimbal mounting means  103  of the turbine-integrated hydrofoil  101  located at the vertices of the triangle  602  away from the center of gravity of the vessel  100 . The pinion member represented by line  603  possesses the same features and characteristics of the variable extension means  104  of  FIG. 1  such as a locking motor mechanism or a generator when unlocked to extract supplemental energy when tension and compression forces act upon the variable extension means. One may note that multiple sides of the triangle formed by lines  602  must act synchronously, with one advantage being less stress to any one member due to distribution of forces among multiple members. Let it be know that the hull and mounting system presented in  FIG. 1  and  FIG. 6  in the preferred embodiment is purely exemplary, illustrative and not restrictive and any alternate hull and mounting system does not represent a significant departure beyond the scope of the present invention. 
         [0026]      FIG. 7  depicts a coupling configuration and energy extraction means from the impeller through to the output conditioning circuitry of the electric generator.  FIG. 7  shows the generator rotor shaft  500  directly coupling to a DC generator  700 . The DC generator  700  may also function as a motor by means of reversing armature current and with the use of the external fins  214  and rotating member  300 , may enable guidance and stability of the vessel  100 . The impeller, not shown in  FIG. 7  in order to maintain simplicity, physically occupies the outline area  205  within the turbine-integrated hydrofoil  101 , while the shaft  500  extends along the axis of rotation, line  200 - 201  as depicted in  FIG. 2  and  FIG. 5 . The DC generator  700  may be any of available forms of DC generator, including but not limited to a commutated or semiconductor-rectified generator, and as shown with a separately-excited or else preferably with a self-excited shunt field winding  721  configuration chosen for its combined simplicity and relatively constant voltage independent of load current. The DC generator  700  thus produces a speed-dependent DC voltage across its armature leads, positive  701  and negative  702 , that feeds the power filtering elements, the inductor  703  and the capacitor  705 . Though two armature leads  701 ,  702  imply a single-phase machine, this is purely exemplary, and no predetermination is placed on the number of phases of the machine in the preferred embodiment. The filtering performed by the inductor  703  and the capacitor  705  minimizes spurs in the electrical waveform caused by commutation. The preferred embodiment of this invention samples the filtered DC waveform at node  704  filtered by inductor  703  and capacitor  705  referencing the negative armature lead  702  to local ground  707  to form feedback that controls the average current through the field winding  721 . The feedback that controls the average field winding  721  current thus controls the torque opposing the impeller rotation thus controlling drag of the vessel  100  and ultimately the armature voltage depending on impeller rotational velocity and load current. 
         [0027]    As previously mentioned, this form of feedback regulation allows relative scaling of mechanical parameters such as openness of the turbine gate  204  affecting vessel  100  drag in a coarse manner, ultimately affecting the power extractable for given pneumatic and hydraulic motive fluid energy levels. For power output means that draw a constant load current, this feedback control of field winding current can compensate for fine, instantaneous variation in the velocity and pressure of the free-flowing motive fluid  202  to produce a relatively constant armature voltage. This feedback control can also most quickly respond accordingly to changes in the free-flowing motive fluid  202  that impart varying levels of torque on the impeller affecting vessel  100  drag in a fine manner and thus avert potentially fatigue-inducing torque on the impeller during extreme conditions characterized by bow breaching and plunging motion imparting varying force on the turbine-integrated hydrofoil  101 . For instance, when the average voltage of the sampled, filtered DC waveform at node  704  exceeds a given threshold, the feedback control will reduce the average current passing through the field coil  721  which in turn, reduces the torque on the impeller while reducing the average armature voltage. Likewise, when the average voltage of the sampled, filtered DC waveform at node  704  recedes below a given threshold, the feedback control increases the average current passing through the field coil  721 , which in turn, increases the torque on the impeller for the benefit of increasing the average armature voltage. While load or armature current, i.e. the electrical current leaving the filtered node  704  and entering the output power conditioning means  724  may vary, responding to load current change may take a subordinate priority compared to responding to changes in motive fluid  202  pressure in order to avert fatigue on the impeller. In one case, an increase in extractable energy from the free-flowing motive fluid  202  or relative velocity of the vessel  100  coincides with an increase in demand for load current, therefore necessitating little change in average current passing through the field coil  721 . Similarly, a decrease in extractable energy or relative velocity of the vessel  100  from the free-flowing motive fluid  202  coincides satisfactorily with a decrease in demand for load current again necessitating little change in average current drawn through the field coil  721 . However, given the extractable energy from the free-flowing motive fluid  202  increases or decreases contrary to a decrease or increase in demand for load current, these situations can elicit limitations in the control loop response. These limitations may manifest in terms of delayed response time, that is, control loop parameters such as loop bandwidth and damping factor that primarily concern stability may slow a response time, producing inadequate transient output voltage or else excessive transient output voltage given a lesser bandwidth or incorrect damping factor. In addition, the design must take into careful consideration the overall headroom for meeting system demands during such instances, and thus varying loads require more design complexity. Therefore the preferred embodiment of this invention powers output means drawing constant current for optimal power conditioning for application to loads such as an electrolyzer, with the relative velocity of the vessel  100  also an input parameter in the overall control loop for the complete system as described in subsequent paragraphs and  FIG. 8 . 
         [0028]    Proceeding further along the path of the local feedback loop,  FIG. 7  depicts two points on the filtered node  704  where sampling occurs. The path including the resistors  710 ,  712  and the capacitor  711  constitute the voltage sampling node of a typical feedback loop with frequency compensation. The network of these resistors  710 ,  712  and the capacitor  711  along with the error amplifier  709  and its own feedback loop represented by the capacitors  714 ,  715  and the resistor  716  form the feedback section of a prior art switch mode power supply. Given the fixed internal reference voltage  713  into the non-inverting input of the error amplifier  709 , resistor  710  along with resistor  708  compose a voltage divider that sets the optimal voltage on the filtered node  704  that feeds the output power conditioning means  724  while this control loop responds to variations in the velocity of the motive fluid  202 . The reference voltage  713  multiplied by the quantity of one plus the ratio of resistor  710  over resistor  708  determines the optimal value of the output voltage of the filtered node  704  that the control loop maintains despite changes in input energy. The other sampling node includes the Zener diode  706  that quickens the response to over-voltage conditions at the sampling node  704 . Resistor  708  must be of correct value in order to allow the Zener current to flow through the diode  708  given this over-voltage condition. The design of the frequency compensation of this error amplifier must also take into account the junction capacitance, though often negligibly small, seen across the Zener diode  706  and parallel to resistor  710 . Resistors  712  and  716  and capacitors  711 ,  714 ,  715  form the frequency compensation of the error amplifier  709  within the feedback loop of a prior art switch mode power supply. While tuning these frequency compensation components is not germane to the specification of the present invention and is elsewhere covered in detail, this specification will now disclose some general observations regarding it. Uncompensated, the filter components, the inductor  703  and the capacitor  705  produce a complex pole pair at their resonant frequency given by one over the quantity of two times pi times the square root of inductance times the capacitance. The filter capacitor  705  also places a zero above the pair of poles at a frequency given by one over the quantity of two times pi times the capacitance and the value of the capacitor&#39;s  705  equivalent series resistance, “ESR”. Generally as a goal in compensation, two zeroes are added near the filter resonant frequency to correct the sharp change in phase near that frequency and an open-loop unity gain frequency is chosen to exist at a frequency about ten times greater than the resonant frequency but less than about 10% of the switching frequency. The overall gain of the error amplifier  709 , the filter components comprising the inductor  703  and capacitor  705 , the two zeroes added plus the gain of the integrator created by the compensation network that sets open-loop unity gain frequency preferably sums to zero at the unity gain frequency. The integrator gain is given by 1/(2(pi)(Fo)(R 710 (C 714 +C 715 ))) where Fo is the open-loop unity gain frequency. The frequency of the output filter compensating zeroes equals 1/(2(pi)(R 716 )(C 715 )) and 1/(2(pi)(R 710 +R 712 )(C 711 )) and these zeroes are understood to add to 40 dB per decade of gain. A pole also exists in the compensation network and its frequency is chosen to coincide with the zero formed by the output capacitor  705  and its equivalent series resistance “ESR”. This compensating pole frequency equals 1/(2(pi)(R 712 )(C 711 )). A final pole in the compensation network exists at the frequency 1/(2(pi)(R 716 )(C 7141  IC 715 )) and is selected to be about ¾ Fs, three-quarters of the switching frequency to reduce switching noise into the error amplifier  709 . While it is understood the precise placement of the pole frequencies, integrator frequency and zeroes frequencies is not of utmost criticality, care must still be taken to follow the aforementioned feedback loop frequency compensation practices to yield best power supply response and stability, and particularly a relatively constant output voltage  704  over the widely varying angular velocity of the rotor  500  resulting from the wide variation of energy within the free-flowing motive fluid. In the past, stability problems have risen due to a negative resistance oscillator formed by cascading switch mode power supplies. For example, the second switch mode power supply in  FIG. 7 , the output power conditioning means  724 , presents a negative resistance because its input current actually decreases with increased input voltage, which in turn may cause instability by adding right-hand s-plane poles in the characteristic equation of the control loop. To prevent this form of instability, the design must ensure the magnitude of the complex impedance of the source, i.e. the DC generator  700  along with the power filtering elements, the inductor  703  and the capacitor  705 , is much less than the magnitude of the input impedance of the output power conditioning means  724  over the entire frequency band of interest, from DC to the unity gain frequency of the feedback loop of the output conditioning means  724 . Careful consideration to all the aforementioned stability criteria ensures long-term reliability and optimal energy extraction over the widest possible range of velocity of the motive fluid  202 . 
         [0029]    Proceeding further along the feedback path depicted in  FIG. 7 , after the error amplifier  709 , a pulse width modulation or pulse frequency modulation controller  717  exists primarily to convert the analog error signal output of the error amplifier  709  into pulses which, after getting conditioned to source and sink large impulses of current by the gate driver buffer  718 , drive the gate of the field coil current switching field effect transistor  719 , ultimately determining the average current drawn through the field winding  721  of the DC generator  700 . The design of the pulse width modulation or pulse frequency modulation controller  717  preferably implements an analog comparator, not shown, that sets and resets logic according to the value of the sampled voltage  704  compared to a fixed reference. In this case, the analog comparator, not shown within block  717 , receives at its inverting input, the voltage signal output from the error amplifier  709 . The non-inverting input of the analog comparator, not shown, receives a DC voltage signal equal to that of the voltage reference  713 , in the same manner as the error amplifier  709 . The analog comparator within the pulse width modulation or pulse frequency modulation controller  71   7  thus compares the inverted output of the error amplifier  709  to a voltage equal to DC reference  713 . Since the comparator within the pulse width modulation or pulse frequency modulation controller  717  is an inverting amplifier referenced to the voltage reference  713 , the filtered output voltage  704  once divided by resistors  710 ,  708  gets inverted through the error amplifier  709 , and this output gets inverted by this comparator. Therefore, the comparator output within the pulse width modulation or pulse frequency modulation controller  71   7  is a logic high signal when the filtered output voltage  704  is above the set voltage and a logic low signal when the filtered output voltage  704  is below the set voltage. This comparator output logic signal is routed out through logic means that finally inverts the signal into the gate driver  718 . Thus when the filtered output voltage  704  exceeds the set voltage, the logic means resets and along with the output of the modulation controller  717  and inputs to the gate driver  718 , goes low, disabling current flow through the field coil current switching transistor  719 . The logic means within the pulse width modulation or pulse frequency modulation controller  71   7  preferably permits the controller  717  to operate in an energy saving “pulse skip” mode. When the output voltage  704  exceeds the set voltage, skipping pulses saves the energy needed to charge and discharge the gate of the field coil current switching transistor  719 . As previously stated, the relative velocity of the vessel  100  presents an input parameter in the overall control of the vessel  100 . Here in the pulse width modulation or pulse frequency modulation controller  717 , the input parameter of vessel  100  relative velocity may induce pulse skip operation. When the relative velocity of the vessel  100  recedes below a given threshold, the pulse width modulation or pulse frequency modulation controller  717  may thereby minimize energy lost in field coil  721  current as well as reduce drag on the vessel  100 . Let it hereafter be known that this means of controlling the average field coil current using switch mode techniques is strictly exemplary and not restrictive, and therefore any changes in configuration, such as but not limited to, choice of pulse width versus pulse frequency modulation, or the polarity of the output logic and according choice of N-type or P-type channel material of the field coil current switching transistor  719 , does not constitute a substantial departure beyond the scope and spirit of the present invention. 
         [0030]    While  FIG. 7  depicts a separately excited field coil as the means of field coil excitation, a self-excited shunt field winding likely proves equally effective, if not more readily realizable due to the amount of current passing through the coil and convenience of not needing the physical space a separate supply  722  occupies. Note that while  FIG. 7  also depicts the catch rectifier  720  as a Schottky diode, that a synchronized switching transistor may be implemented in its place at the expense of greater complexity in the logic of the controller  717  and an additional gate driving buffer similar to gate driver buffer  718  but for the benefit of increased power efficiency. As well known by those skilled in the art, because the field coil  721  is inductive, when the current is switched, the field coil voltage is reversed proportional to the inductance multiplied by the change in current with respect to time. Using a simple catch rectifier  720  can protect the switching transistor  719  from over voltage while feeding that stored energy back to recharge the separately excited field winding source  722  or back into the armature terminal  701  in the case of a self-excited shunt field winding, thereby returning the stored energy in the field coil  721  back to the system, increasing the system power efficiency. A synchronous switching rectifier that has a lower voltage drop across it depending upon drain to source on-resistance and rectifying current compared to the catch rectifier  720  gains further efficiency. The complexity of the synchronous rectifier lies in the precision required to prevent the field coil current switching transistor  719  including its gate capacitance from having an on-time that coincides with the on-time of the transistor including its gate capacitance that replaces the catch diode  720 . Having on-times that coincide effectively short-circuits the field winding leads and thus short-circuits the field winding excitation source. Conversely, the longer delay in turning-on the synchronous rectifying transistor reduces the gain in efficiency. Digital timing circuitry within the controller  71   7  may achieve the goal of precise timing necessary, given a known tolerance for the gate capacitances of the switching transistors. Whether the system of controlling average field coil current implements a simple catch diode or a synchronous rectification circuit, both circuits remain within the scope of the present invention. 
         [0031]    While this specification previously presented a chopped field coil current controlled DC generator as the preferred embodiment, equivalent generator configurations exist within the scope of the present invention. In one embodiment, the generator  700  alternatively exists as an AC induction generator of adequate number of poles such that its synchronous speed, which determines whether the AC machine is operating in its generator or motor region according to its torque-slip curve and is inversely proportional to the number of poles, is well below the average rotational velocity of the rotor  500  and therefore the AC machine operates with positive slip as a generator. What makes the AC induction generator desirable is its economical, reliable construction and widespread use, rendering this type of generator easily attainable and cost effective. In the case of unavailability of an AC induction generator of sufficient number of poles for an adequately low synchronous speed to operate with positive slip given the average rotational velocity of the rotor  500 , the AC induction generator indirectly couples to the impeller through a gear system. This gear system increases the rotational velocity of the rotor shaft  500  with respect to the impeller. The gear system likely occupies the outline area of the fluid coupler  205  in proximity to the generator  700 . In order to directly apply the voltage from the AC induction generator to the load through wires  725 ,  726 , the electrical circuit represented by output conditioning means  724  contains a speed dependent switch that receives an input signal from a velocity transducer sensing the rotation of the rotor  500  in the outline area of the fluid coupler  205 . The velocity transducer output signal therefore also needs to physically traverse the same path as the leads  701 ,  702  either on its own conductor or modulated upon the armature coil power current. This speed dependent switch affords highest efficiency and protection such as when the coupler shaft has inadequate velocity for positive slip, or there exists a fault condition on either side of the output conditioning means  724 , the AC generator becomes disconnected from the load. This gear system including automatic transmission to change the impeller to rotor gear ratio to achieve constant output voltage amplitude over varying fluid velocities, rotational velocity transducer, and speed dependent switch effectively replaces the filtering components  703 ,  705 , and the entire field current controlling feedback loop of the previously described DC generator system. The output conditioning means  724  could thus be physically located in the hull  102  away from the generator unit, with the leads  701 ,  702 , routed from the generator  700 , through the support structure  217 ,  218 ,  103 , out along the beam  105  through the extension means  104  to the hull  102  location of the output conditioning means  724 . As with the leads before, the output conditioning means  724 , though only a pair of wires  725 ,  726  is shown implying a single-phase system, this is purely exemplary with no predetermination of the number of phases that may be applied to the utility power grid. 
         [0032]    Returning to the DC generator implementation, a variety of loads may be applied by connection to the leads  702 ,  704  depending upon end user needs. Examples of loads include charging any variety of available chemistries of battery, or the leads  725  and  726  themselves terminating as the electrodes in the process of electrolysis of water to produce hydrogen fuel. In both cases here, the output means  724  will likely require the protection of the transient voltage suppressor  723 , shown in  FIG. 7  as a Zener diode, from inductive spikes caused by commutation. Here in these examples of output loads as in all foregoing descriptions, the local ground  707  attached to lead  702  purely references the negative differential voltage output of the generator  700  and all other associated references in the field coil current controlling feedback system, not ordinarily referenced to true earth ground and thus not the chassis ground potential of the turbine-integrated hydrofoil  101  and for that matter, quite likely completely isolated from the negative differential voltage lead  726  from the output power conditioning means  724  which may or may not be referenced to a true earth ground potential. 
         [0033]    In the case of the load being the charging batteries, the output conditioning means  724  could occupy a physical location within the turbine-integrated hydrofoil  101  in the instance of the battery being the excitation source  722  for another DC generator  700 . But in other applications, because the process of battery charging generally requires low-error voltage sensing at the battery terminals and low-error temperature sensing from a thermistor within the cell packaging powered by an accurate reference, the design more feasibly and economically locates the charger section of the output power conditioning means  724  in proximity of the battery unit charging in the hull  102 . Therefore the leads  725 ,  726  likely route high voltage from the output power conditioning means  724 , through the support structure  217 ,  218 ,  103 , out along the beam  105  through the extension means  104  to the hull  102  location of the battery and associated charger. 
         [0034]    In the preferred embodiment, the load is the current required to perform electrolysis on water to produce hydrogen fuel. This process achieves a high efficiency due to inherent advantages in the preferred embodiment of the present invention. Seawater is naturally electrolytic thereby reducing chemical processing costs; and advanced electrolysis methods allow for a voltage as little as one and a half to two volts applied across the electrodes, which the generator  700  in the self-excited shunt field winding configuration can easily provide over a wide range of rotational velocities of the rotor  500 . Given the requirements for such a system for electrolysis, the output conditioning means  724  in one case consists of simply a very high efficiency synchronous switch mode buck or in other words, step-down DC-to-DC converter, with some form of current regulation, to provide the appropriate voltage to the electrodes  725 ,  726  to perform electrolysis. In this case, synchronous switch-mode DC-DC conversion cannot provide isolation of the local ground  707  from true earth ground, which may or may not be tolerable for the configuration of DC generator  700  implemented, though desirable due to its simplicity and optimal efficiency. If the DC generator  700  absolutely requires ground isolation, then a flyback or forward DC-DC converter with synchronous rectification within the output power conditioning means  724  achieves the next highest efficiency. Because this output power conditioning means  724  is relatively simple and compact, it can occupy an area adjacent to the generator  700  within the turbine-integrated hydrofoil  101 , with the leads  725 ,  726  routing conditioned DC power to the electrodes contained within the appropriate sections of the electrolyzer. For simplicity, the system preferably reduces wire losses by minimum distance routing a low voltage and high current through copper bars  725 ,  726  to the electrolyzer where the power is then directly applied to the electrodes  211 . The leads  725 ,  726  terminate as the electrodes, particularly the anode and cathode, respectively, for the electrolyzer, and thus the anode  725  references to true earth ground as the hydrogen collects at the cathode  726  while the system isolates both the gas and electrical potential at the cathode  726  from the surrounding environment. One means of using seawater for hydrogen electrolysis consists of admitting seawater through a filter membrane in a reverse osmosis process for desalination then adding potassium hydroxide as an electrolyte for increased electrolyzer efficiency. In the preferred means, the filter membrane is coarse enough to allow seawater with salt less the silica particulate, and the anode  725  is plated with manganese dioxide to minimize the amount of sodium hypochloride, NaOCI, also known as sodium chloroxide or bleach that collects at the anode  725 . This preferred electrolysis method saves the cost in energy to perform reverse osmosis desalination and processing the sodium chloroxide by-product otherwise an environmental contaminant. 
         [0035]    Alternately, the output power conditioning means  724  may take the AC voltage produced by an AC induction generator in place of the DC generator  700  from leads  701 ,  702  and full-wave rectify the AC voltage into a DC voltage, then filter and further regulate the voltage and current for optimal power conditioning for application to loads as described in the foregoing paragraphs regarding DC power generation. 
         [0036]      FIG. 8  illustrates the overall control of all the components described thus far of the complete turbine-integrated hydrofoil for adaptively extracting energy from a free-flowing motive fluid that continuously changes direction and magnitude of flow. While  FIG. 8  displays a flowchart, which is ordinarily associated with a computer program running in software, the algorithm delineated may be implemented with any combination of hardware or software such as linear or analog circuits or discrete digital circuits or an integrated central processing unit, or a microprocessor. A central processing unit or microprocessor affords the advantage of convenient means to gauge, test, and remotely communicate using well-defined existing wireless standards to a central service logging and energy distribution location, the state of any part or process of the system, including but not limited to functionality, guidance, stability, drag, velocity, or fullness of batteries or hydrogen fuel tanks. Furthermore, a local central processing unit or microprocessor may receive control signals guiding the vessel  100  towards maximal weather conditions from a remote control and service facility with means to track weather conditions. Such remote control means could permit unmanned operation of the vessel  100 . From the start  800 , the controller is continuously sampling and storing  801  such variables as position, velocity, acceleration, weight, and level of vessel; velocity of motive fluids; armature voltages; fuel tank fullness; electrolyzer temperature; and energy efficiency. From the sampling and storing  801  processes, the system control algorithm proceeds in two concurrent paths through the remainder of the flowchart. While not specifically stated in block  801 , it may be assumed all sampled variables including the signals representing various input parameters including the armature voltage are sampled and stored in a likewise continuous, concurrent manner as implied by the looping arrow exiting only to return to the upper right corner of block  801 . In the preferred embodiment, the period for sampling the motive fluids velocities has a time resolution necessary to react to and control mechanical processes, ordinarily sampling at an approximate frequency of about a hundred times a second, or a period of about ten milliseconds, with a small deviation allowable possibly due to the convenience of a local non-integer multiple frequency digital clock from which to derive this sampling clock frequency. This algorithm then averages the samples over a space of five to ten samples, this average representing a single sample in order to reduce the effects of noise. It is reasonable that the processes controlling motive fluid related adjustments such as turbine gate openness in block  802  need to occur, or most efficiently occur for that matter, no more often than ten to twenty times a second. The vector sum of plural motive fluid velocities is then computed to determine the vessel  100  trajectory to plot for optimal energy extraction by directing towards the highest relative vessel  100  velocity vector. This highest relative vessel  100  velocity vector then gets communicated back to a central remote control facility if implemented. 
         [0037]    In practically all conceivable embodiments, there always exists the path that serves to adjust the field coil  721  current to optimize generator  700  armature voltage, while minimizing the necessary torque exerted on the impeller and drag on the vessel  100  over a range of relative velocities of the free-flowing motive fluid  202 . Thus in the flowchart of  FIG. 8 , the path proceeds from the sampling block  801  to the process block  802 , where the instantaneous magnitude of the sampled generator armature voltage is compared to an upper threshold. This upper threshold likely equals in excess of one hundred percent of, but less than two times, the rated voltage of the generator  700 . Various types of circuits may perform this comparison through either digital sampling followed by numeric comparison or through analog means to control the average field coil  721  current such as the control feedback loop previously described with  FIG. 7 . Hence, the outcome of this comparison in block  802  determines whether to increase or decrease the average field current accordingly. Using means described previously and depicted algorithmically in  FIG. 8 , this block  802  exists to process the sampled instantaneous magnitude of the output voltage to determine the average field coil  721  excitation current by means of feedback control processes applied in order to optimally extract energy from a free-flowing motive fluid. If implemented digitally, the number of samples per second corresponding appropriately to slightly greater than two times the unity gain loop bandwidth previously described, defines the sampling period per the Nyquist criterion. This digital algorithm, like the preceding analog circuitry, allows the generator to produce a maximum voltage while mitigating the risk of fatigue upon the impeller  205  throughout the extremes of usable flow, while also minimizing drag on the vessel  100  throughout the range of vessel  100  relative velocities. 
         [0038]    The previously described paths through the flowchart of  FIG. 8  perform mathematical manipulations on sampled output voltages of sensors in order to determine the appropriate course of action. It shall be known that any of the paths could share the outputs of these mathematical functions in order to improve the overall control algorithm. The previously cited example of this refers to when the relative velocity of the vessel  100  recedes below a given threshold, the pulse width modulation or pulse frequency modulation controller  717  may skip pulses that determine the generator average field coil  721  excitation current to minimize energy lost in field coil  721  current as well as reduce drag on the vessel  100 .  FIG. 8  further shows by decision block  803  how the magnitude of vessel  100  relative velocity may feed into the control of most other processes. Block  804  deals with insufficient magnitude in vessel  100  velocity, whereby reduction in vessel  100  drag is in order to increase velocity, or minimize vessel  100  extreme instantaneous instability, hence reduce the average field coil  721  to reduce torque on the impeller  205  as well as close the turbine gate  204  and the gate to the electrolyzer depending upon temperature. Block  804  suggest two other means of reducing vessel  100  drag depending upon vessel  100  stability thereby increasing velocity including reducing the distance of the hydrofoil from the center of gravity of the vessel  100 , along with lifting the ballast  106 . Block  804  also suggests adjusting the pitch of the hydrofoil  101  to improve dynamic lift at the lower vessel  100  velocity. Block  805  deals with optimizing extractable energy once the vessel  100  attains sufficient velocity for the hydrofoils  101  to provide maximum dynamic lift. This action includes opening the turbine gates  204  and increasing the average field coil  721  excitation current resulting in increased armature voltage from the generators  700 . Another input parameter into this block  805  comprises vessel  100  stability, consisting of a computed standard deviation of level over many samples as sensed by accelerometers, gyroscopes, camera-based pattern recognition means, or any other presently available inertial displacement sensing means. In block  805 , vessel  100  stability and velocity form input parameters into control of distance of hydrofoils  101  from the center of gravity of the vessel  100  and control of ballast draft itself having a third input variable of fuel tank  106  fullness. Decision block  806  makes a high level decision affecting vessel  100  trajectory based on tank  106  fullness. If the tank fullness is below a given threshold as shown in block  807 , the vessel  100  stays its present course towards maximal weather conditions or maximal relative velocity vector as computed in block  801 . If the tank fullness appears above a given threshold, the vessel  100  should plot a trajectory back towards the central distribution destination to dock its payload, all the while adjusting ballast  106  draft according to aforementioned stability computations. While not explicitly depicted for sake of clarity in the flow diagram of  FIG. 8 , it may be inferred that any deviation of the algorithm to include the additional use of these function output variables in decision blocks, or for that matter, use of a singular central processor to also concurrently perform these and other control tasks not explicitly depicted, such as, but not limited to: charging batteries; or performing electrolysis; maximizing energy efficiency; or electronic means of vessel  100  velocity, drag, stability, or guidance control; or logging communications; does not constitute a substantial departure beyond the scope of the present invention. [Para 40] From the detailed description above it is manifest that various implementations can use the concepts of the present invention without departing from its scope. Moreover, while the invention has been described with specific reference to certain embodiments, a person of ordinary skill in the art would recognize that significant alterations could be made in form and detail without departing from the spirit and the scope of the invention. The described embodiments are to be considered in all respects as illustrative and not restrictive. It shall also be understood that the invention is not limited to the particular embodiments described herein, but is capable of many rearrangements, modifications, omissions, and substitutions without departing from the scope of the invention. 
         [0039]    Thus, a turbine-integrated hydrofoil for adaptively extracting energy from a free-flowing motive fluid that continuously changes direction and magnitude of flow has been described.