Abstract:
A free floating wave energy converter includes a flexible pine and an inlet. The flexible pipe floats on water surface, following the wave form. Slugs of water and air enter, one after the other, through the inlet. Because the flexible pipe follows the shape of the wave, water is transported through a manifold to a pressure chamber connected to a generator. The inlet consists of hollow, inflexible pipe attached to the throat of the flexible pipe. The inflexible pipe is fixedly attached to a buoyancy tank or plurality thereof. The buoyancy tanks are arranged in a vertical plane or in tandem, with the inflexible pipe passing along the plane vertical to the fore and aft axis of the buoyancy tank and the frontward portion projecting sufficiently ahead of the buoyancy tank with the flexible pipe terminating at a singular outlet.

Description:
FIELD OF THE INVENTION 
     The invention relates to an improved free floating wave energy converter. More particularly, the invention relates to an improved free floating wave energy converter “IFFWEC” relating to ocean wave energy converters (WEC). 
     BACKGROUND OF THE INVENTION 
     Free floating wave energy converters have been disclosed in applicant&#39;s earlier patent/patent application numbers AU2006274564 (A1), BRPI0614487 (A2), CA2617208 (A1), EP1915528 (A1), EP1915528 (B1), JP2009503362 (A), NO20081115 (A), NZ566247 (A), US2008229745 (A1), U.S. Pat. No. 7,823,380 (B2), US2011006531 (A1), WO2007015269 (A1) and ZA200801801 (A). 
     The original invention essentially comprises of a flexible pipe, or plurality thereof, that floats on the ocean surface and adapts to the wave form, suitably moored so as to maintain the fore and aft axis generally towards the waves direction. Special “Inlet”, attached at the mouth of the flexible pipe, ingests graduated slugs/segments of air and water into the “Flexible Pipe”, synchronous with the waves. 
     Fluid pressure is built up in the “Flexible Pipe” until it is sufficiently high to drive a turbine or pump ocean water into reservoirs, etc. Several such pipes could be grouped to make a wave energy farm. With the rest of the conditions remaining constant, increase in the number of “Flexible Pipes” and length, enhances the flow volume and pressure, respectively. 
     In US application 20100276933, wherein the principle of “overtopping” has been exploited to run turbines. A similar approach has been adopted for one of the devices disclosed herein, but to feed water to an “Inlet” system. 
     The principle of “Air Lift Pumps”, with patents of more than 100 years vintage, has also been exploited in yet other sub-systems disclosed herein, but with certain differences. For instance, air pressure is being supplied from within the system in this case, and not fed from outside as in the case of the published material. 
     SUMMARY OF THE INVENTION 
     The present invention discloses several improvements made and some retrofit devices invented to overcome issues experienced and anticipated with the systems disclosed at original applications listed above. However, to provide continuity the original drawings, with the reference numbers, have been retained. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  depicts the principle of operation of the present invention; 
         FIG. 2A  is an artist&#39;s impression in perspective of the “Free Floating Wave Energy Converter” according to the invention; 
         FIG. 2B  depicts a preferred embodiment of the invention; 
         FIG. 3  shows air and water “Slugs” in the “Flexible Pipe” during idling and pressure flow conditions; 
         FIG. 4  shows a typical “Inlet” of the invention; 
         FIG. 5  shows the “Inlet” with buoyancy control; 
         FIG. 6  shows the “inlet” with an inflatable buoyancy tank and control; 
         FIG. 7  shows the “Inlet” with a plurality of inflatable buoyancy tanks and control; 
         FIG. 8( a )  shows a hydro/pneumatically actuated inlet of the invention in side view,  FIG. 8( b )  is a front view,  FIG. 8( c )  is a baffle type variation,  FIG. 8( d )  is version with a channeled ramp and  FIG. 8( e )  is version with a hinged channeled ramp; 
         FIG. 9  shows a Flat-Conical Intake; 
         FIG. 10  shows an Air-Water Separator; 
         FIGS. 11A-11C  show various inflatable tubes associated with the flexible pipe. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description and appended drawings describe and illustrate various exemplary embodiments of the invention. The description and drawings serve to enable one skilled in the art to make and use the invention, and are not intended to limit the scope of the invention in any manner. In respect of the methods disclosed, the steps presented are exemplary in nature, and thus, the order of the steps is not necessary or critical. 
     Certain design principles to achieve the desired results are discussed in the succeeding paragraphs. 
       FIG. 1  of the accompanying drawings illustrates the behavior of the air and water slugs in a flexible pipe arrangement. For ease of understanding, we have considered the waves to be regular curves, such as in the case of a “U tube manometer”, connected in series  101 . Let us also assume that, initially, water  102  is filled uniformly in all trough segments  101 A of the pipe  101 , with air  103  being trapped in crest segments  101 B. It can be seen that, since all the segments  101 A,  101 B are connected in series, any force applied at any point on the pipe  101  will be transmitted throughout the length of the pipe. Thus, if some pneumatic pressure  104  is applied at one end of the pipe  101 , it will “push” all the water segments/slugs up preceding crests  105  (against gravity). In other words, a pressure head will be created, which will be equal to the sum total of all the height displacements of the water segments. 
       FIG. 2A  depicts an artist&#39;s impression of the FFWEC which describes an arrangement  201  depicting waves moving towards ashore  202 , reflected waves near shore (“turbulence area”)  203 , and a plurality of “Flexible Pipes”  204  connected at one end to a plurality of “Inlets”  205 , respectively, further connected at opposite ends to a “Manifold”  206  and the manifold  206 , by means of a pipe  207  or plurality thereof, in fluid communication with the “Pressure Chamber” or “Pneumatic Accumulator”  208  or plurality thereof. The pressure chamber  208  is further connected by means of “Air and Water Piping”  209  to generators  210  or turbines. Moorings  211  are provided at the “Inlets”  205 ; supports  212  may be provided for the pipe  207 . At least one drain pipe  213  is connected to the chamber  208 ; and a grid power supply  214  is connected to the generators  210 . 
     Even though some of the systems above have been shown to be on shore, but could even be located offshore. Likewise, pneumatic pressure could also be developed by pneumatic compressors instead of the pressure chamber. It would also be possible to develop power directly from the fluid flow from the “outlet”. The various pipes for fluid communication could also be in plurality. The aforesaid means and methods are preferred options and not the only possibilities. 
       FIG. 2B  is an enlarged view of the preferred embodiment of the invention essentially comprising the “Flexible Pipe”  204  connected at one end to the “Inlet”  205 . An “Outlet” or coupling  215  is attached to an opposite end of the pipe  204  and is further connected to components shown in  FIG. 2 . A “Suspension Rod”  218  extends downwardly from the “Inlet”  205  and optionally includes a “Ballast/Damper”  219  and a mooring ring  220 . A mooring line  221  is attached to the ring  220 . 
       FIG. 3  of the present invention depicts a “Flexible Pipe”  301  floating on waves, with water  302  and air  303  “Slugs” in sustained flow. A water reservoir  309  connected to the outlet of the pipe  301  is located at an elevation towards the outlet side of the flow representing the extent of a pressure-head  304  on the flow, with the direction of wave motion being from left to right (arrow  305 ). With no back pressure (no water in the tank  309 ) the water “Slugs”  302  remain in the troughs of the pipe  301 , and with water in the tank  309 , the slugs  302  are pushed up the preceding wave crests  306  to generate an increased pressure-head  308  on the flow. 
     The basic embodiment in  FIG. 4  shows an “Inlet” apparatus  420  comprising a single “Inflexible Pipe”  400 , at least one buoyancy tank  401 , which tank normally floats on the surface of a body of water represented by a wave  409 . Through a mouth  402  of the pipe  400  both air and water can enter and an outlet  403  of the pipe is connected in fluid communication with a front end of a “Flexible Pipe”  404 . 
     Further, the apparatus  420  additionally and generally consists of a “Suspension Rod”  405 , either fixedly attached to the apparatus or hinged to it. In the former arrangement, the Suspension Rod  405  could have a “Ballast” and/or “Damper  406  and a mooring ring  407  with an attached mooring line  408 , all suspended below the apparatus, for providing and enhancing stability to the assembly, particularly in a vertical axis  418 , that is to minimize the pitching motion of the assembly, while providing freedom to heave viz. along the vertical axis. These components if positioned below the buoyancy tank  401  minimizes the torque that would otherwise be created by the moment arm formed, due to the distance between a Center of Floatation “F”  415  and a center of gravity (CG)  416 . Hence, both are kept aligned along the Vertical Axis  418  or nearest thereto. 
     Whereas, in the former case the “Inflexible Pipe”, i.e. the fore and aft axis of the Inlet  400 , has a freedom to pitch around the lateral axis and as well to heave. The “ballast”  406  also acts as a “damper”, creating drag while moving up and down the waves. Thus, if it is located away from the Center of Floatation “F”  415 , somewhere along the fore and aft axis of the Inlet, it would cause torque, thereby making the mouth  402  of the “Inflexible Pipe”  400  pitch up and down while riding the waves; which aspect is discussed subsequently herein below. It may be noted that, at the time of the “Zero Start” it would be necessary to push water into the mouth  402  of the “Inflexible Pipe”  400 , at the required velocity and volume. Therefore, it would be necessary to have a relative motion between the horizontal component of the waves and the “Inflexible Pipe”  400 . This does not happen if the “Inlet”  420  pitches along with the waves. The “Ballast”  406  enhances stability of the “Inlet”  420  in the vertical axis  415 , thereby minimizing the pitching motion, as required in some embodiments of the present invention. The “Flexible Pipe” 404 , which trails the apparatus  420 , provides the directional stability. As such, it remains nearly in an upright position and rightly aligned as it floats up and down the waves. 
     The Inlet  420  generally faces the oncoming waves  409  (direction arrow  410 ) and is made to float at an appropriate distance from the (SWL) by adjusting the buoyancy of the buoyancy tank  401 . Under operating conditions, it typically enters near a trough  411  and exists at a crest  412  of the waves  409  as they pass (for explaining the sequence, the wave  409  in the drawing is shown as stationary while the “Inlet”  420  is shown in three positions, moving from right to the left). When a wave  409  strikes the mouth  402  of the “Inflexible Pipe”  400 , the water which enters it is separated from the main water body, while continuing to move through it at the same wave velocity. The “Water Phase”  414  commences from the trough of an oncoming “Air Phase”  413 . Thus, the alternating intake of water and air “Slugs” is appropriately synchronized with the waves  409 . The entry (crest  412 ) and exit (trough  411 ) points vary depending upon factors, such as the back-pressure at the “outlet”  215 , wave conditions, the length of the “flexible pipe”  204 , etc. and is suitably controlled. 
     The system could work without any controlling devices, under fair wave climatic conditions, with average efficiency and reliability. However, since the waves are not regular, provision for optimally controlling and regulating the air and water ingestion timing and volume have also been provided. 
     The intake volume and timing of air and water “Slugs” are controlled by altering the buoyancy and/or “up-down” tilting of the “Inlet” along its lateral axis. Buoyancy is increased or reduced by filling the buoyancy tanks with air or water, respectively. Alternatively, the Inlet  420  could also be pushed in and out of water by certain actuation means or with baffle arrangement. This enables ingestion of the “Slugs” according to the wave condition. 
     Inlets having means for controlling and regulating the buoyancy, whereby the air and water ingestion timing and volume could be controlled to a certain degree, besides making it possible to ingest only water to sink the apparatus/system in bad weather or ceasing operations by ingesting only air and totally float it, are described in detail below. 
       FIG. 5  illustrates the above embodiment comprising an “Inlet” apparatus  501  with at least one “Buoyancy Tank”  502  having a “Pneumatic Duct”  506 , a top end  506 A of which opens in a top portion of the “Buoyancy Tank”  502 . The duct  506  is connected through a hose  505  to the “Pressure Chamber”  208  ( FIG. 2 ) with some control systems/devices  808  preferably located thereat, for varying the pneumatic pressure in the “Buoyancy Tank”  502 . By varying the pneumatic pressure in the “Buoyancy Tank”  502 , water is pushed in/out through a “Water Breathing Tube”  507 , a top end of which is fixedly attached to the bottom of the “Buoyancy Tank”  502  and a lower end opening into the sea below, consequently varying the “Inlet”  501  buoyancy, thereby controlling the air and water intake timing and volume. The rest of the arrangements of this embodiment remain similar to those described in  FIG. 4  above, including an “Inflexible Pipe”  503 , connected to a “Flexible Pipe”  504 , a “Ballast”  508  optionally attached to the tube  507 , a mooring ring  509  attached at the bottom of the tube  507 , and a mooring line  510  attached to the ring  509 . 
     In another embodiment, an “Inlet” apparatus  601 , which is illustrated by  FIG. 6 , includes at least one “Inflatable Buoyancy Tank”  602  which is directly connected with a pneumatic hose  605  as above, but without the “Pneumatic Duct” and “Water Breathing Tube” (the rest of the arrangements being similar to the previous embodiment described in the above paragraph). The hose  605  terminates at a duct  606  inside the tank  602 . An “Inflexible Pipe”  603  is connected to a “Flexible Pipe”  604 , a bracket  607  attaches a suspension rod  608  to the pipe  603 , a “Ballast”  609  is provisionally attached to the rod  608 , a mooring ring  610  is attached at a bottom end of the rod  608 , and a mooring line  611  is attached to the ring  610 . 
     As can be appreciated, the buoyancy of the “Inlet” apparatus  601  can be varied by inflating/deflating the “Inflatable Buoyancy Tank”  602 . The inflatable variable buoyancy tank  602  could be, as shown in  FIG. 6 , a spherical shape or any other suitable shape and its principle operation also being similar in each case. 
     In yet another embodiment illustrated by  FIG. 7 , an “Inlet” apparatus  701  comprises at least two “Inflatable Buoyancy Tanks”  702 , connected individually, in groups or jointly through respective hoses  705  and  706  with the “Pressure Chamber”  208 , or pneumatic compressors, which may be shore based and having the pneumatic pressure and controls and switching devices generally installed thereat. The “Inflatable Buoyancy Tanks”  702  are suitably arranged on the “Inlet” apparatus  701 , whereby the pitching, i.e. the angle of rotation around the lateral axis of the “Inlet” apparatus and its buoyancy, can be controlled by varying the buoyancy of the “Inflatable Buoyancy Tanks”  702  individually. Also shown are an “Inflexible Pipe”  703  connected to a “Flexible Pipe”  704 , brackets  707  for attaching a “Suspension Rod”  708  and the pipe  704  to the pipe  703 , a “Ballast”  709  attached to the rod  708 , a mooring ring  710  attached to an end of the rod  708 , and a “Center of Flotation” (F)  711 . The tanks  702  encircle the pipe  703  and also can be positioned on the rod  708 . 
     If the “Damper”  709  is located at a certain distance aft of the “Center of Floatation” (F)  711  (instead of vertically below it as described at  FIG. 5  for instance, and the Suspension Rod  708  may be hinged to the apparatus so as to enable pitching, the drag caused by the “Ballast/Damper”  709  would create some torque, which would make the “Inlet”  701  tilt/pitch “up”, with (F) as the fulcrum, while it rides up the waves, and vice versa. In this case, the water which would be in the “Inflexible Pipe”  703  during the “Water Phase”  414  ( FIG. 4 ) would also be lifted up by the additional pitching motion of the “Inlet”  701 , causing it to fill the empty “Flexible Pipe”  704  at “Zero Start”. The angle of rotation of the “Inflexible Pipe”  703  can be varied by changing the buoyancy of the respective buoyancy tanks  702 . 
     In another embodiment, at least two “Rigid Buoyancy Tanks”, similar in construction to the “Buoyancy Tank”  502  explained at  FIG. 5  above are used, instead of the Inflatable Buoyancy Tank  602  of  FIG. 6 . The arrangement of the components and their functions is similar to that explained in  FIG. 7  above, including the “Inflexible Pipe, the “Flexible Pipe”, the “Suspension Rod, the “Ballast” and the mooring ring. 
       FIG. 8( a )  through  FIG. 8( e )  are the schematic representations of Hydro/Pneumatically Actuated Inlet systems  800  having certain alternative components and controls. The systems enable more precise, quicker and positive control of the air/water phases  411 - 412 , as compared with the previous systems, whereat the “Inlet” apparatus  420  typically entered near a trough  411  and existed at a crest  412  of the waves as they passed. The means and method of controlling those operations have already been described at  FIG. 5 to 7 . 
     Whereas, in embodiment depicted at  FIG. 8( a ) , an inlet  803  is sequentially lifted above  804 A and pushed below  804 B the water surface, with more precise timing. The higher pressure below water surface also helps in pushing water slugs into the inlet  803  and when it is lifted to a height, a “head” is also created, both factors help in forming distinct water slugs and also imparting velocity to them, particularly at the time of “Zero Start”. The device could additionally have a tilting mechanism. 
     This system  800  includes a suspension means  801 , depicted as an inverted “U” frame, at least one buoyancy tank  502  attached to pylons  801 A on either side of the suspension means  801 . The buoyancy tanks  502  having control features similar to those described at  FIG. 5  through  FIG. 7  and the relevant paragraphs above (not shown). 
     The inlet pipe  803 , which may have shapes and dimensions different from the other inlet pipes  401 ,  501 ,  601 , etc. disclosed herein, is attached to one end of a reciprocating mechanisms; for instance levers, guides, scissor jack or lift, that is operated by linear actuator, for instance bellow or cylinder, typically cylinder  804  as shown in  FIG. 8 , further attached to the “Flexible Pipe”  204 , and its other end  804  to the horizontal beam  801 B of the suspension means. 
     The inlet pipe  803  reciprocates along the vertical axis, by means of at least one linear actuator  804 , between fully retracted (in air)  804 A and fully extended (in water)  804 B positions. The linear actuator  804  could be pneumatic or hydraulic system, driven by air, oil or even sea water. 
     Pneumatic pressure is provided through hoses  505  in fluid communication with the linear actuator  804  and a compressed air source (not shown), such as the pressure chamber  208 . Alternatively, the fluid could even be hydraulic oil or sea water driven by external pump. The reciprocating and rotary motions of the inlet pipe  803  are triggered by suitable sensing and control system  808  with inputs from the phase of the wave at the inlet pipe  803 , the back pressure at the “outlet”  215 , length of the “Flexible Pipe”  204 , wave conditions or wave climate, energy demand, etc. 
       FIG. 8( b )  depicts a rotary actuator  802 , mounted on inlet pipe  803 , attached to the lower end of the actuator  804  and, enables rotation of the inlet pipe  803  through certain degrees around the lateral axis ∠Ø. 
       FIG. 8( c )  depicts yet another version of the Hydro/Pneumatically Actuated Inlet  800 . The “Baffle Type” Inlet  805  system has two inlet pipes; instead of a single Inlet  803  previously described in the present invention, one each for water  806  and air  809  ingestion, respectively. Air  807 A and water  807 B are alternately ingested through the respective pipes. A baffle  810  alternately closes either the air port  810 A or water port  810 B, while the opposite one automatically opens, thereby feeding the respective slugs into the flexible pipe  204 . An actuation system  813 , similar in construction to the cylinder actuator device  804 , is employed to operate the baffle valve  810 , through suitable UP/DOWN  812  linkage mechanism. The rest of the components remain similar to those described at  FIGS. 8( a ) and 8( b )  above. 
     The main difference between the “Baffle Type” Inlet  805  system and the rest described in the present invention is that, the water  806  and air  809  ingestion pipes always remains under water and above water, respectively; as shown in the diagram with “WATER”. In this embodiment, instead of pushing the Inlet  803  in and out of water, either air  807 A or water  807 B, slugs are ingested with the baffle opening and closing the respective ports. This arrangement requires comparatively lesser time and force to alternate the between the two phases, besides causing minimal disturbance to the water flow. However, it also entails more number of moving components. 
     While certain type of actuators  802 ,  804  have been mentioned, any other type of actuator could be used. The phase of a wave at the inlet pipe  803  could be sensed by any of the various suitable sensors available for measuring wave heights, time period, etc. (not shown). In most of the previous Inlet devices disclosed above, the phase velocity of a wave was being directly converted into flow of water slug. However, since the “water ingestion phase”  414  mostly commences near a trough  411 , where the velocity in the direction of flow is not only low, but could even be out of phase by 180°. Hence, there was a possibility of water slugs not getting enough “push” or kinetic energy to suddenly accelerate to the phase velocity at the right moment, particularly at the time of the “zero start”. To overcome this mismatch, it would be possible to first convert the kinetic energy at the crest of a wave into potential energy; by topping up water in a reservoir or tank located at a height, storing it there, and then reconverting it into kinetic energy—by accelerating a slug to the desired velocity, volume and wave phase, particularly at the time of “Zero Start”. Some embodiments to enable the above sequence of operation are disclosed below. 
       FIG. 8 ( d )  discloses yet another embodiment of the Automatic Inlet ( 814 ) consisting a tank fed inlet  816 , with a tank  815  suitably attached on top of the tank fed inlet  816  and  815  being in fluid communication with the tank fed inlet  816 , through a telescopic pipe or flexible hose  817  of adjustable length. The tank fed inlet  816  is further in fluid communication with the flexible pipe  204 , via baffle  810  that opens/closes either the air port  810 A or water port  810 B ports, wherein the tank fed inlet  816  functions as in the case of the “Baffle Type” Inlet  805  above. 
     A channeled ramp is  818  attached to the tank  815 , such that its trailing edge is jointed in front and top of tank  815  and its front edge is near the SWL. 
       FIG. 8( e )  is a version of the Inlet system disclosed at  FIG. 8 ( d ) , consisting an Inlet  819 , with a tank  815  suitably attached on top and in fluid communication with the inlet  819 , through a telescopic pipe or flexible hose  817  of adjustable length. The inlet  819  is further in fluid communication with the flexible pipe  204 , via a first baffle  810  that opens/closes either the air port  810 A or water port  810 B. 
     The Inlet  819  further having a second baffle  811  located in front of the first baffle  810 , wherein the second baffle  811  opens/closes either the ocean port  811 A or tank port  811 B, actuated by means of an actuating system  813 . In the ocean port “Open”  811 A/Tank “Closed” position, water from the ocean can flow through the tank fed inlet  816 , via first baffle  810 , further into the flexible pipe  204 , as in the case of  FIG. 8 ( d ) , while the tank port  811 B would remain “Closed”, and vice versa. 
     When the ocean port  811 A is “open”/tank port  811 B “closed”, the inlet  819  functions as Inlet  805 ,  FIG. 8( c ) . Whereas, when tank port  811 B “open”/ocean port  811 A “closed”, the inlet  819  functions as in the case of tank fed inlet  816 ,  FIG. 8( d ) . 
     Further, a Channeled Ramp  818  is rotatably hinged  819  to the tank  815  and can be moved “UP”  818 A/“DOWN”  818 B by means of a similar actuating mechanism  813 . It  818  is lowered till its front edge is near the SWL  818 B to enable overtopping of the tank  815  by moving waves, generally at the time of “Zero Start” and lifted “Up” for continuous operation. Since the velocity of the water slug entering the Tank fed inlet  816  will be a function of the “head” ‘h’ of the water level in the tank  815  above the Tank fed inlet  816 , the desired slug velocity can be achieved by adjusting the “head” ‘h’, which can either be set manually, based on the average celerity in the area of deployment, or automatically by a servo mechanism (not shown), according to the inputs from sensing  808  devices. However, the latter option would increase the sophistication, with consequent cost escalation, O&amp;M problems, etc. Hence, the manual option is preferable, more so because the requirement of feeding water at some pressure and velocity would mostly at the time of “zero start” or kick-start. 
     The rest of the arrangements are generally similar to those described at  FIG. 8 ( a ) through ( d )  above. The various structural components being generic in nature have not shown, to avoid clutter. 
     A “rod” and “ballast/damper” arrangement  406 ,  708 ,  709  and  710  described at  FIG. 5  and  FIG. 7  is optionally attached to tank fed inlet  816  in line with the Centre of Gravity “CG”  416 . The ballast/damper  709  maintains the inlet system  805 D aligned in vertical position, along the vertical axis, and as well dampens the heaving motion as it rides the waves. The rationale for this has already been covered at the description of  FIGS. 5 and 7  above. Since the inlet system  805 D resists following wave motion, waves roll up the ramp and fill the tank  815 , where water is stored till let into the  816  by opening inlet port  810 B. 
     It would also be possible to combine features of one embodiment with another. For instance, a larger diameter pipe or tank  815  could be attached at the front the tank fed inlet  816  of the inlet. When and lifted up and tilted backwards water would flow into the inlet  803  at the required velocity and timing. Baffles  810  would be precluded. 
     Another feature of the invention is a “Flat-Conical Intake”  900  (hereinafter termed as the “Intake” to distinguish it from the “Inlet”  205 / 420 . It is a well-known fact that the larger pipe diameter the lesser the frictional loss, with the other factors remaining constant. Due to this reason, where on one hand small diameter pipes are not suitable due to their higher frictional loss at the wave velocities expected in the ocean, on the other the large diameter pipes are ineffective when the wave heights are comparatively smaller. 
     This is mainly because, in this case, (a) the mouth of the “Inlet” may not completely enter a trough  411  and exit at a crest  412 , but remain partially in both, air and water most of the time. Thus, integrated water slugs may not form, precluding development of the liquid seals which are essential for building up pressure, and (b) the large diameter “Inlet” would take a longer time transiting through the air-water. During this period, both air and water would simultaneously enter the “Inlet”  420 , creating a situation similar to the one described at the previous paragraph. The “Intake” is meant to resolve these problems. 
       FIG. 9  depicts an “Intake”  900  consisting of a hollow conical body  901 , a narrower mouth with rounded rectangular cross section  902  and a cylindrical outlet  903  to suit the flexible pipe  204 . The cross sectional area of the “Intake” is maintained nearly constant all along its length and it smoothly blends from rounded rectangle to circular shape thereby providing better fluid dynamic characteristics. The Intake could either be attached directly to the “Flexible Pipe”  204 , or mouth of the “Inlet”  205 / 420 . The intake  900  assists in ingestion of water particularly in shallower wave climate. 
     An additional feature of the invention includes an “Air-water Separator”  1000 . It may be possible to pump water up beyond a certain height in an arrangement which works on the principle of “U Tube Manometer”, such as the present invention, notwithstanding the amount of pressure that may be applied or is being generated by the “flexible pipe”. 
     Reference is made to  FIG. 1 . Now, if the pneumatic pressure  104  is increased, the “water slugs” 101 A, that are already at the “MINIMUM WATER LEVEL”  105  cannot be pushed up any further, but the “liquid seals” that were formed by the “water slugs”  101 A, will be breached and the air  103  that was trapped in the “air slugs”  105  will bubble out through the “water slug”  105  at “Minimum Water Level”. Some water from the “water slugs”  105  may also spill over into the adjacent trough segment. As a result of this, the pressure  106  will drop to some extent, and air will continue to escape as long as it is being pumped in. 
     Reference is also made to  FIG. 3 , “SLUGS UNDER PRESSURE”. In this case too, if a “water slug”  302  happens to go below its “Minimum Level”, the “liquid seal” would similarly be breached, consequently enabling the air pressure to escape. As the “air slugs”  303  get depleted, the buoyancy that was being provided by them would also decrease, resulting in sagging of the “Flexible Pipe”  204  between two adjacent “air slugs”  303 , causing them to merge. Consequently, the “flexible pipe”  301  could sink. This phenomenon is more prominent in case the “head”  308  is more than the height of the “water slug”  306 , and the pipe diameter is also large; for instance even 10 cm ID Whereas, it would be around a meter in diameter in the field conditions. As solution to this problem, the “Air-water Separator”  1000  is described below. 
       FIG. 10  depicts the “Air-water Separator”  1000 , viz. an apparatus attached at the discharge side of the “Flexible Pipe”  204  or “Manifold”  206  or “Outlet”  215 . Water and air from the “outlet”  215  are pumped under pressure into the Air-Water Separation Tank  1002  and get segregated in it, with air and water flowing upwards and downwards, respectively, due to gravity. The fluids are further conveyed to the Pressure Chamber  208  and/or turbines/generators  210 , via the air  1003  and water  1004  pipes  209 , respectively. The air pressure is pumped by means of the air hose  1003  and injected into the Pressure Chamber  208 , through the “Air Discharge Nozzle”  1005 , the mouth of which is located below the SWL, at a given depth and termed as the “Differential Pressure Depth”  1007 . 
     The water level in the Air-Water Separation Tank  1002  is maintained at the “Differential Pressure Level”  1010 , i.e. somewhere below the “outlet”  215 , irrespective of the pressure head H. This is because; the Air Discharge Nozzle”  1005  is located at the “Differential Pressure Depth”  1007 , viz. below the SWL. The pressure required to displace water from the Air Discharge Nozzle”  1005  also acts on the top surface of the Air-Water Separation Tank  1002 , pushing the water in it down by an equal depth, i.e. to “Differential Pressure Level”  1010 . The “Pressure Chamber  208 ” and Air-Water Separation Tank  1002  hold slugs and column of water, respectively, in equilibrium, making it a closed system. 
     The flow of water and air under pressure from the “Flexible Pipe”  204 , via the Air-Water Separation Tank  1002 , will build-up a pressure head “H” in the “Pressure Chamber  208 , and get discharged through the Water Piping  209  to run the turbine  210 . The air bubbles injected into the “Pressure Chamber”  208  will increase the volume of the fluids in it and as well assist in enhancing the upward flow of the fluids, consequently increasing the Pressure head “H”. Thus, the pressure energy in the compressed air is also utilized. 
     The principle of the “Air Lift Water. Pump” or “Geyser Pump” is applied in the case of case, with the exception that, the water to be lifted and the pneumatic pressure, both, are supplied from the same source, i.e. the “flexible pipe”. The air pressure/pneumatic is pumped back into the system, increasing the total efficiency or minimizing energy loss as well. 
       FIG. 11A  shows a selectively inflatable and deflatable tube  1300  attached to the “Flexible Pipe”  204  along a length of the flexible pipe, wherein the tube is coiled around the flexible pipe. The inflatable tube  1300  is inflated at the time of “Zero Start” and deflated when the system is running in a stable condition. By this method sagging during startup could be precluded. The pressure in the inflatable tube  1300  could also be varied between inflated deflated to depending on the operating conditions. A source of pneumatic pressure supplies pressured air to the tube, wherein when the tube is inflated by the pressured air, a buoyancy of the flexible pipe is increased to prevent the flexible pipe from sagging or sinking in the body of water. 
       FIG. 11B  shows pair of inflatable tubes  1300  externally and laterally attached on either side of the “Flexible Pipe”  204  along its length. On the left hand side of the drawing is a front view  1301  of the same. 
     The inflatable tubes  1300  are inflated at the time of “Zero Start” and deflated when the system is running in a stable condition. By this method sagging during startup could be precluded. The pressure in the inflatable tubes  1300  could also be varied between inflated deflated to depending on the operating conditions. 
     Pneumatic pressure can be supplied from the pressure chamber ( 208 ) or an external source and controlled by a controlling means. 
       FIG. 11C  shows another embodiment which restrains the “Flexible Pipe”  204  from sinking beyond a preset depth/limit  1303 . In this case an inflatable/deflatable tube  1302  is disposed vertically above the “Flexible Pipe”  204 . The inflatable/deflatable tube  1302  is attached with the Flexible pipe  204  by means of tethers  1308 , ropes or strands of the required length, for restraining the flexible pipe  204  from going below the depth/limit  1303  below the wave surface. For instance, if the length of the tethers  1303  is 1 m, the water segments will be restrained from going below this depth. Pressure in the inflatable/deflatable tube  1302  can be varied to extend the depth/limit  1303  to some extent. 
     Pneumatic pressure is supplied to the inflatable/deflatable tube  1300 ,  1302  from the “Pressure Chamber”  208  or any other external source. The pressure in the inflatable/deflatable tubes is controlled with control devices externality located. 
     In the above case too, the selected depths  1303  can be varied in steps as described above. 
     In another option for this embodiment, instead of the inflatable tube, inflatable/deflatable balloons are used. 
     Besides compressibility, the other significant factor that will affect the functioning of the FFWEC is the rise in temperature due to compression, per Charel&#39;s Law/Gas Law. However, it will mostly get absorbed by the water. Conversely, at the time of expansion in the “Pressure Chamber”  208  generators  210 , the temperature will fall which could cause freezing, particularly when operating at low temperatures, such as in the higher latitudes. Besides loss of energy/heat, more energy would have to be spent in heating the fluids to prevent freezing. Therefore, to conserve energy the “Flexible Pipe”  204  is suitably insulated by wrapping it with thermal insulating material or providing built-in insulation. 
     For mooring it is preferable to use mooring buoys, since the weight of the mooring line would be taken up by the buoys and not act on the “Inlet” or system as such. 
     The orientation of the flexible pipes is of significance for energy extraction. Energy is progressively extracted by a “Flexible Pipe”. Hence, if it is disposed directly along the wave direction, the maximum energy that it can absorb will be limited to the energy of the wave front acting on its cross section, i,e. area of the mouth of the pipe. Whereas, if it is laid at certain angle to the wave direction, energy would be progressively absorbed as a wave travels along the length of the pipe. 
     Various other permutations and combinations of the same principle of operation and arrangements are also possible, but not mentioned herein 
     In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.