Patent Publication Number: US-2013241205-A1

Title: Power Generating Apparatus

Description:
The present invention relates to apparatus provided on a vessel for generating power using wave motion. In particular, but not exclusively, the invention relates to generating power using a vessel subject to pitch and roll due to wave motion. 
     Various wave power devices exist. Often, the apparatus use the vertical rise and fall of a device such as a buoy to generate power. The entire apparatus has to be manufactured and subsequently has no other purpose than to generate power, and the cost of the apparatus can be substantial. 
     A vessel such as a ship or boat is subject to pitch (longitudinal rotation) and roll (lateral rotation) when at sea. Even in calm weather, a ship typically experiences around 10° of roll. The vessel may have ballast tanks and/or stabiliser fins to control stability. The pivot point about which the vessel rolls is termed the metacentre, m. This is different from, and generally higher up than, the centre of gravity, g. The vertical position of g depends on the weight of the vessel and, if lower decks are flooded using the ballast tanks, the mass of the vessel will be greater at the bottom and so g will move downwards. However, the position of the metacentre will not change. 
     Conventionally, diesel engines are used to power a ship. A typical cost of the heavy fuel oil used for the engines is around $30,000 per day. The ship typically travels in shipping lanes and one reason these lanes are chosen is that they are generally calm waters. However, they are often not the most direct route between destinations. 
     According to a first aspect of the present invention, there is provided a power generating apparatus which is installable on a vessel, the apparatus comprising:
         a power generating device;   a movable actuator coupled to the power generating device such that movement of the actuator causes the generating device to generate power; and   a mass which is movable in at least a first direction and a second opposite direction due to pitch or roll movement of the vessel,   wherein the apparatus is adapted such that movement of the mass causes the mass to impact and move the actuator to generate power.       

     The movable actuator may comprise a piston which is retractable to compress or move a fluid. The power generating device may comprise a turbine which is moved by the fluid to generate power. 
     The mass may comprise a rolling member, such as a ball or cylinder. Alternatively, the mass may comprise a sliding member. 
     The apparatus may include a guide member for the mass. The guide member may be adapted to limit movement of the mass to the first and second directions. The guide member may comprise one or more rails, troughs, conduits or the like for the mass. The mass may be rollably or slidably connected to the guide member. 
     The mass may be linearly movable in the first and second directions. Alternatively, the mass may be rotationally movable in the first and second directions. 
     In an alternative embodiment, the mass may comprise a hammer member. The hammer member may be pivotably fixed at a surface of the vessel and rotatable about the pivot fixing to impact and move the actuator. 
     A set of two actuators may be provided. The mass may be provided between the two actuators. The guide member may extend between the two actuators. Each actuator may be provided at opposite ends of the vessel in a lateral or longitudinal axis of the vessel. 
     Alternatively, the mass may comprise a component of the vessel, such as cargo or a portion of the infrastructure of the vessel. The apparatus may include a support member for the component which provides controlled movement to impact and move the actuator. Alternatively, the mass may comprise a fluid contained within the vessel which is movable due to pitch or roll to apply pressure to the actuator to move the actuator to generate power. 
     The effective distance between the two actuators of the set may be variable. The apparatus may include sensing means for measuring the frequency of the pitch or roll of the vessel. The apparatus may include control means for varying the distance between the two actuators based upon the measured frequency. 
     The apparatus may include a pitching or rolling sensor to measure the magnitude of movement of the vessel. The apparatus may include means for preventing or limiting movement of the mass when the magnitude of vessel movement exceeds a predetermined value. The means may be adapted to cease movement of the mass, or to limit the movement to within a set of stops, or to slow movement of the mass. The means may comprise a cage member, an anchor device, a set of stops, a brake member or the like. 
     The apparatus may include means for controlling the amount of pitch or roll of the vessel. The controlling means may comprise means for varying the distance between the metacentre and the centre of gravity. The varying means may be provided by ballast tanks of the vessel. Alternatively or in addition, the controlling means may comprise one or more stabiliser fins which are deployable to reduce pitch or roll or retractable. 
     A plurality of sets of actuators may be provided at the vessel, the sets being serially arranged in a horizontal direction. The horizontal direction may be one or both of lateral and longitudinal. Alternatively or in addition, a plurality of sets may be serially arranged in a vertical direction. The mass of the mass and/or the number of sets provided at a particular vertical level may vary depending on the vertical distance from the metacentre. 
     The vessel may comprise a ship or boat. The vessel may be anchorable at a first point of the vessel. The first point of the vessel may be provided at one end of the vessel and the vessel may be anchorable at a second point at a second opposite end of the vessel. 
     The first and second anchoring points of the vessel may vertically correspond to the metacentre of the vessel. The first and second anchoring points of the vessel may be provided at each longitudinal end of the vessel. This restrains the vessel from movement in all directions except for rolling rotation about the metacentre. Alternatively, the first and second anchoring points of the vessel may be provided at each lateral end of the vessel. This restrains the vessel from movement in all directions except for pitching rotation about the metacentre. 
     An arm assembly may be provided at the metacentre for extending the anchoring point outwards towards or beyond the boundary of the vessel. This avoids interference between the anchor line and a portion of the vessel such as the hull. 
     The apparatus may include an electrical conduit which is connectable between the power generating device and an onshore connector. 
     Alternatively or in addition, the generated power may be stored in storage devices on the vessel such as batteries. The generated power may be used to power the vessel. The vessel may be adapted to carry cargo and/or passengers. 
     According to a second aspect of the present invention there is provided a vessel including a power generating apparatus in accordance with the first aspect of the invention. 
     According to a third aspect of the present invention there is provided a method of generating power comprising the steps of:
         installing on a vessel a power generating apparatus comprising a power generating device and a movable actuator coupled to the power generating device such that movement of the actuator causes the generating device to generate power;   providing a mass on the vessel, the mass being movable in at least a first direction and a second opposite direction due to pitch or roll movement of the vessel such that movement of the mass causes the mass to impact and move the actuator to generate power.       

     The method may include guiding the mass to limit movement of the mass to the first and second directions. The method may include providing the mass between a set of two actuators. 
     The method may include using a component of the vessel, such as cargo or a portion of the infrastructure of the vessel, as the mass. Alternatively, The method may include using a fluid contained within the vessel as the mass. 
     The method may include varying the effective distance between the two actuators of the set. The method may include measuring the frequency of the pitch or roll of the vessel. The method may include varying the distance between the two actuators based upon the measured frequency. 
     The method may include measuring the magnitude of movement of the vessel. The method may include preventing or limiting movement of the mass when the magnitude of vessel movement exceeds a predetermined value. 
     The method may include controlling the amount of pitch or roll of the vessel. The step of controlling the amount of pitch or roll of the vessel may comprise varying the distance between the metacentre and the centre of gravity. 
     The method may include providing a plurality of sets of actuators at the vessel. 
     The method may include anchoring the vessel at a first and second point of the vessel, the points provided at opposite ends of the vessel. The method may include vertically locating the first and second anchoring points at the metacentre of the vessel such that the vessel is restrained from movement in all directions except for rotation about the metacentre. The method may include providing an arm assembly at the metacentre to extend the anchoring point outwards towards or beyond the boundary of the vessel. 
     The method may include connecting an electrical conduit between the power generating device and an onshore connector. 
     Alternatively, the method may include storing the generated power in storage devices on the vessel. Alternatively or in addition, the method may include using the generated power to power the vessel. 
     The method may include sailing the vessel within one or more geographic regions that are known to produce substantial pitch or roll. The or each geographic region may be distinct from known shipping lanes. 
     According to a fourth aspect of the present invention there is provided a method of anchoring a vessel comprising the steps of:
         connecting an anchor line of a first anchor at a first point located at a first end of the vessel;   connecting an anchor line of a second anchor at a second point located at a second opposite end of the vessel; and   deploying each anchor,   wherein each of the first and second points correspond to the metacentre of the vessel such that rotational movements of the vessel are unconstrained while movement in all other degrees of freedom is constrained.       

     The first and second anchoring points of the vessel may be provided at each longitudinal end of the vessel. Alternatively, the first and second anchoring points of the vessel may be provided at each lateral end of the vessel. 
     The method may include providing an extending member at one or both of the first and second points and connecting the anchor line to the free end of the extending member. 
    
    
     
       Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
         FIG. 1  shows a side view of a vessel including a first embodiment of a power generating apparatus; 
         FIG. 2  shows a plan view of the vessel of  FIG. 1 ; 
         FIG. 3  shows an end view of the vessel of  FIG. 1 ; and 
         FIG. 4  shows a second embodiment of a power generating apparatus; 
     
    
    
       FIG. 1  shows a vessel in the form of a ship  100  in a body of water  110  which includes a power generating apparatus  10  as shown in  FIGS. 2 to 4 . The apparatus  10  comprises a power generating device in the form of a turbine device (not shown) which converts rotation of a set of turbine blades into electricity. 
     The turbine blades are rotated when a movable actuator in the form of the head  22  of a piston  20  is retracted to pressurise a hydraulic fluid. The piston  20  includes a spring (not shown) for returning the piston head  22  to the extended position. 
     As shown in  FIGS. 2 and 3 , a piston  20  is provided at each lateral end of the ship  100 , the two pistons forming a cooperating set, and a guide channel  24  extends between the two pistons  20 . A mass in the form of a heavy ball  26  is located within the channel  24 . The ship  100  includes a number of these piston/channel/ball systems arranged in series and running laterally across the ship  100 . 
     The ball  26  is free to roll within the channel  24  from one end to the other and back in response to rolling of the ship  100 . As the ship  100  rolls, each channel  24  will change in orientation to have a particular gradient, the value of the gradient dependent on the degree of rolling. The ball  26  at the summit of the gradient will roll along the channel  24  in direction A, picking up momentum and accelerating as it rolls. When the ball  26  reaches the end of the channel  24 , it will strike the piston head  22  located there with an impact force equal to the product of its mass and deceleration as it slows to a stop at the end of the channel  24 . This impact force is predetermined to be sufficient to fully retract the piston head  22 . Each piston/channel/ball system will therefore contribute to generating power. The balls  26  will all tend to move simultaneously in the same manner as they are all subject to the same rolling action of the ship  100 . 
     It is desirable that the balls&#39; striking of the piston heads  22  is coordinated with the peaks of rolling of the ship  100  to fully utilise the available energy of the rolling balls  26 . Therefore, it is desirable to ensure that the rolling distance of the balls  26  (determined by the length of the channels  24 ) corresponds with the frequency of rolling of the ship  100 . To achieve this, the effective distance between the set of two piston heads  22  can be adapted to be variable. For instance, one or both pistons  20  can be attached to a mount (not shown) which is laterally movable inwards towards the centre of the ship  100 . One or more sensors (not shown) can be used to measure the frequency of the roll of the ship  100 . A controller (not shown) can be adapted to vary the distance between the two piston heads  22  by moving one or both of the associated mounts by a distance based upon the measured frequency. 
     One or more sensors (not shown) can also be provided to measure the magnitude of rolling movement of the ship  100 . When the rolling of the ship  100  as measured by the sensors exceeds a safe value, movement of the balls  26  can be prevented or limited. For instance, a brake in the form of rubber pads (not shown) provided in the channels  24  can be deployed to slow the balls  26  or, if further deployed, bring the balls  26  to a stop. The degree of deployment of the brake can be adapted to be dependent on the measured magnitude of rolling. Slowing, rather than stopping, the balls  26  has the advantage that the apparatus continues to operate (and produce power) even in harsh conditions. 
     It is also possible, either instead of or in addition to directly controlling ball movement, to control the amount of roll of the ship  100 . This can comprise varying the distance between the metacentre and the centre of gravity. Two means of doing this are using the ballast tanks of the ship  100  and the stabiliser fins of the ship  100 . 
     Also, the steering of the ship  100  can be controlled, in response to the measured magnitude of rolling movement of the ship  100 , so that the ship  100  is at the optimum orientation for experiencing rolling within the desired range. 
     As shown in  FIG. 3 , the piston/channel/ball systems can also be serially arranged in a vertical direction. The mass of the balls  26  can be adapted to vary depending on the vertical distance from the metacentre m. 
     As shown in  FIGS. 1 and 2 , the ship  100  can be anchored at two points  40 , the points  40  provided at opposite longitudinal ends of the ship  100 . The anchoring points  40  are configured to vertically correspond to the metacentre of the ship  100 . This restrains the vessel from movement in all directions except for rolling rotation about a longitudinal axis  42  passing through the metacentre m, whereas the rolling rotation is substantially unrestrained. An arm assembly  44  coincident with the metacentric axis  42  extends the anchoring points  40  outwards to avoid interference between the anchor line  46  and the hull of the ship  100 . 
     With this configuration, the ship  100  is permanently anchored for as long as power generation is desired. The ship  100  can be anchored close to shore and an electrical conduit (not shown) can be connected between the power generating device and an onshore connector connected to the main grid. 
     However, the ship  100  can alternatively be used as a working vessel, such as to carry cargo and/or passengers. The generated power can be stored in batteries and can be used to power the vessel which would provide a substantial reduction in fuel costs. 
       FIG. 4  shows an alternative embodiment of the apparatus  10 . Rather than using a ball which rolls within a channel, the mass comprises a hammer  50  which is again provided between two piston heads  22 . The hammer  50  is pivotably fixed at a surface of the ship  100 . Rolling of the ship  100  causes the hammer  50  to rotate relative to the ship  100  about the pivot fixing  52  to sequentially impact and move each piston head  22 . 
     Various modifications can be made without departing from the scope of the present invention.