Abstract:
A plant for producing electrical power from the movement of waves. An offshore dam has a fixed generally vertical surface which is located in open water having wave movement and located vertically at the water surface. A submerged part which is fixed relative to the dam has an opening below the waves and in close proximity to the plane of the vertical surface to receive sea water. A force exerting structure such as a hydraulic pump or a thrust arrangement receives the water through the opening and forces that water through a one-way valve beyond which it is led to a turbine for producing electric power.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a plant for producing electric power from the movement of waves. 
     BACKGROUND OF THE INVENTION 
     As is known, at present various systems for producing electric power from the movement of waves are known, said systems, for example, being able to make use of the fluctuating movements of sea waves in order to operate devices which are situated, for example, on a wall against which these waves suitably connected to electric power generators collide. Another type of system for obtaining power from the movement of waves consists in complex apparatus provided with buoys anchored to the seabed and completely submerged: the continuous motion of the waves imparts a continuous movement to these buoys which are anchored to the seabed and which in turn are connected to floating cylinders co-operating with actuator means connected to electric generators. The principle of these systems is therefore essentially that of causing the movement of a piston, which may also be an oscillating water column, inside a chamber under the continuous action of the wave movement and transferring this movement, in a manner which is entirely known, to an electric power generator. 
     These systems, however, have often proved to be very complex to produce and their efficiency does not achieve fully satisfactory results. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to provide a plant for producing electric power which is economically advantageous, which is simple in terms of its constructional design and which ensures an optimum operating efficiency. 
     This object is achieved by the present invention by means of a plant for producing electric power from the movement of waves, characterized in that it comprises an offshore dam for separating a section of sea inside it, such as a port zone, from an open-sea section and comprising towards this open-sea section a submerged part which has, formed therein, one or more ducts and/or inlets for receiving the water, provided upstream and/or downstream with non-return valve means; at least one turbine connected to electric power generating means is positioned in this offshore dam or in a land zone also at a distance from this offshore dam; this turbine is connected upstream to at least one water supply duct in turn connected upstream to a force exerting structure such as a suitable pumping means or thrust means able to convey the water received via these ducts and/or inlets towards this duct for supplying water to this turbine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further characteristic features and advantages of the present invention will be better understood during the course of the following description provided purely by way of a non-limiting example with reference to the accompanying drawings in which: 
         FIG. 1  shows a first side elevation view of a first embodiment of the present plant for producing electric power from the movement of waves, comprising a float shown schematically on a crest of a sea wave and a hydraulic pump which directs water to a turbine connected to an alternator and housed on an offshore dam; 
         FIG. 2  shows a second side elevation view of this first embodiment of the plant according to  FIG. 1 , with the float shown schematically in a trough of a sea wave; 
         FIG. 3  shows a side elevation view of a second embodiment of the present invention in which the plant comprises a duct for recirculating the water used in a turbine; 
         FIG. 4  shows a side elevation view of a variation of embodiment of the invention according to  FIG. 3 , in which the present plant comprises a tank for storing the water prior to entry into the turbine; 
         FIG. 5  shows a side elevation view of a further embodiment of the present plant, comprising an inlet formed in the offshore dam on the open-sea side and provided with a ramp sloping upwards; 
         FIG. 6  shows an elevation view of a variation of embodiment of the plant according to  FIG. 5 ; and 
         FIG. 7  shows a further embodiment of the invention according to which the plant is supported by a floating platform anchored to the sea bottom. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the accompanying drawings and with particular reference to  FIG. 1  thereof,  1  denotes schematically a sea wave which is formed by a series of crests  101  and troughs  201 .  2  denotes a float connected to a hydraulic pump  6  housed inside an offshore dam  17  and containing a piston  4  movable vertically inside a cylinder  5 . A rod  3  emerges from this cylinder at the top and connects said piston  4  to said float  2 . The hydraulic pump  6  is connected moreover to a series of ducts  12 ,  13 ,  14 ,  15  into which the water flows in given directions depending on opening or closing of a series of four non-return valves  7 ,  8 ,  9  and  10 . These ducts are formed inside the offshore dam  17  on which a turbine  16  connected to an alternator for producing electric power is positioned. The ducts  12  and  13  are connected to duct  11  for supplying the water to the turbine  16  and connected to a cylinder  5 , while the ducts  14  and  15  are connected to this cylinder  5  and water from an open-sea section  22  is conveyed inside them. This turbine  16  and this alternator may also be situated in a land location close to a shoreline; in this case the supply duct  11  must have a certain length and must have suitable dimensions since the hydraulic pump  6  and the float must be positioned in any case where the wave movement has a certain intensity. The valve  7  is provided upstream of the duct  12 , situated on one side close to the top of the cylinder  5  and shown in an open position, while the valve  8  is provided upstream of the duct  14 , being shown in the closed position. This duct  14 , at the opposite end to the valve  8 , is connected to the cylinder  5  close to the top thereof, on the opposite side to the duct  12  and substantially at the same height with respect to the latter. The duct  13  is connected to the cylinder  5 , close to the base of the latter and has upstream the valve  9 , shown in the closed position. The duct  15  is positioned on the opposite side of the cylinder to said duct  13 , substantially at the same height and therefore close to the base of said cylinder  5 , and has upstream a valve  10  shown in the open position. 
     In the figure, the float  2  of the present plant, according to this first embodiment of the invention, is situated at the top of a crest  101  of the sea wave  1 : the piston  4 , joined to this float  2  by means of the rod  3 , will have therefore performed a movement from the bottom upwards inside the cylinder  5  in order to reach the position shown, causing opening of the valve  10  which allows the entry of a certain amount of water through the duct  15  inside this cylinder  5  into the zone underneath this piston  4 . After completion of the rising movement of the float  2  as far as the crest  101  of the wave  1 , and therefore the piston  4  into the vicinity of the cylinder  5 , the descending movement of this float will start, as can be seen in  FIG. 2  of the accompanying drawings, until it reaches the trough  201  of this wave  1 . During the downward movement the float  2  will push the piston  4  downwards so that it reaches, in the region of the trough  201  of the wave  1 , a position close to the bottom of the cylinder  5 . During the downward movement this piston  4  pushes the water introduced into the cylinder  5  in the manner described with reference to  FIG. 1  and therefore the valve  9  will open and the valve  10  will close, and the water will flow out from the duct  13  so as to reach the supply duct  11  and therefore the turbine  16 . At the same time the downward movement of the piston  4  causes the entry of a certain quantity of water from the duct  14  which is positioned at the top on one side of the cylinder  5  and therefore the valve  8  will open and the valve  7  will close. This quantity of water, which in this case is collected above the top part of the piston  4 , will be directed towards the supply duct  11  in the manner shown in  FIG. 1  upon rising again of said piston  4  and therefore through the open valve  7  and the duct  12 . 
     Obviously, a series of the plants described above may be arranged along the offshore dam  17  and it is also possible to envisage several hydraulic pumps  6  in series so as to optimize further the efficiency of the plant and be able to reach a predetermined power. The present plant may also use the waste water in order to decontaminate the internal water of the port. 
       FIG. 3  shows a second embodiment of the present plant. In this case the offshore dam  17  comprises a seat  18 , which is preferably cylindrical, inside which the float  2 ′ may slide, said float, as can be seen, having an upper section  102 ′ and a lower section  202 ′ which are substantially conical or frustoconical, so as to facilitate the upward and downward movement thereof, also in the case of sea waves of smaller amplitude. Underneath this float  2 ′, the offshore dam  17  has, formed therein, an expansion chamber  21  for the incoming sea wave, which communicates with the section  22  of seawater outside the offshore dam  17  and is provided with a suitable water inlet opening situated above the hydraulic pump  6 . As can be seen, the hydraulic pump  6  is similar to that shown in the previous embodiment, while the duct  11  conveys the water delivered by this pump  6  to the turbine  16  and from here to a further recirculation duct  19 . The water used in the turbine  16  enters into this recirculation duct  19  and may be used to decontaminate a section  20  of seawater inside the offshore dam  17 , for example if this dam bounds a port zone where it is likely that there will be a certain stagnation of the water. 
       FIG. 4  shows a variant of the embodiment of the plant described above. In this variant the offshore dam  17  has, formed inside it, a tank  23  which receives, via the duct  11 ′, the water drawn by the hydraulic pump  6  prior to its entry into the turbine  16 . A chamber  24  is formed underneath this tank  23  and houses the turbine  16  which is connected to the alternator. This chamber  24  comprises at the top a duct  25  communicating with the tank  23 , so as to be able to supply by means of gravity said turbine  16  with the water flowing into it. The seat  18  inside which the float  2 ′ slides, as mentioned, is preferably cylindrical and has a constant internal radius; therefore the dam  17  comprises simply an inlet  26  for the water of the open-sea section  22 . As can be seen, the offshore dam  17  rests on a rock base  27  and the duct  19  for recirculating the water used in the turbine passes along the section  20  of seawater inside the offshore dam  16  along the bottom thereof. In the figure the piston  4  and therefore the float  2 ′ are shown substantially in their equilibrium position, namely when the float  2 ′ is situated at the middle level of the seawater, from where it will move up on the crest of a sea wave as described with reference to  FIG. 1  and then fall into the trough as described with reference to  FIG. 2 . The form of this float  2 ′ is shown in broken lines in the case of very large waves and in this case the piston  4  will reach the upper end-of-travel position inside the cylinder  5 . 
       FIG. 5  shows a further embodiment of the present invention. In this variant the offshore dam  17  has, formed therein, below the level of the open-sea section  22 , an inlet  28  with an opening which is sufficiently wide and a water flow cross-section which suddenly narrows towards a non-return valve  29  which is situated substantially at the same level as the seawater and therefore on the top of this inlet  28 . This inlet  28  comprises at the bottom a ramp  31  sloping upwards and a vertical wall  32  on one side. A duct  30  for supplying the water to the turbine  16  connected to the alternator is shown beyond the non-return valve  29 . This turbine  16  directs the water towards the recirculating duct  19 . The energy transported by the sea wave  1 , upon encountering this sloping ramp  31  and the vertical wall  32  inside the dam  17 , is projected upwards and together with the kinetic raising energy causes opening of the non-return valve  29 , conveying water and compressed air into the duct  30  supplying the turbine  16 . 
       FIG. 6  shows a variant of this embodiment described in which the duct  30 ′ has a greater height and length than the duct according to  FIG. 5  and conveys the water into the storage tank  23  provided at the bottom with the duct  25  which directs the water by means of gravity to the turbine  16 . 
       FIG. 7  shows a further embodiment of the invention. According to this embodiment the plant, which is similar to the plant described with reference to  FIG. 3 , is supported by a floating platform  33  anchored to the sea bottom  36  by means of for example 4 struts  34  hinged at one end at  37  to corners the base of the platform  33  at their other end at  38  to four anchor logs or sinkers  35 . 
     Of course, the plant according to the invention can also be made in form of a prefabricated elements made from sheet metal or concrete, to be secured to the existing dams. 
     As can be seen from the above description there are numerous advantages which may be obtained by means of a plant for producing electric power from the movement of waves in accordance with the various embodiments of the invention shown by way of example, and numerous further variants may be adopted in order to achieve these advantages without departing from the scope of the accompanying claims.