SUBMERGED HYDROPNEUMATIC WAVE ENERGY CONVERTER

Abstract: A hydro-pneumatic wave and heave power station for converting wave and heave energy, whereby for utilizing the hydrostatic pressure difference of the amplitudes of wave tops and wave valleys with a continually shifting phase, two or more mutually co-operating but mechanically not coupled pistons (2, 19) with a relatively large diameter are used, which, during downward movement, use the pressure difference for directly driving hydraulic cylinders (10, 21), which by means of a hydraulic rectifying circuit (14) transfer their kinetic energy to a hydraulic motor (18) coupled with an electrical generator, which pistons are returned again towards their highest position by means of a gas (4) compressed during the downward stroke, which gas, after expansion, is still in equilibrium with the water column above the piston, the generated electrical current being transferred by means of cables towards a utilization or distribution point on the mainland.

Description: SUBMERGED HYDROPNEUMATIC WAVE ENERGY CONVERTER The invention relates to a hydro-pneumatic installa¬ tion, intended for converting wave and heave energy into electrical energy in such a manner that the energy of the vertical movements of the water masses per unit of effec- tive surface area will be maximally utilized. In contrast to prior systems, which have been parti¬ cularly developed for this alternative manner of energy production, the principle of operation is not based on floats moving up and down with the waves, which floats transfer their kinetic energy in some manner (and often by means of complicated transmissions) to an electrical generator, but using the hydrostatical pressure difference of wave tops and valleys having a continually shifting phase, which power station is constructed in the manner formulated in the characterizing portion of claim l. Favourable embodiments are mentioned in the subclaims. The invention will be elucidated below by reference to a drawing, showing in: Fig. 1 a simplified diagrammatical vertical section of a power station according to the invention; and Figs. 2 and 3 a diagrammatical top and lateral view respectively of a plural power station according to the invention. A large piston 2 situated below a wave top 1 is, in the situation shown, moving downwardly, which movement stops as soon as the sum of the own weight and the hydro¬ static pressure of the water column 3 above this piston is in equilibrium with the pressure of gas compressed in an underlying pressure chamber 4, which chamber is freely communicating with an accumulating vessel 5. This amply sized vessel 5 serves for influencing the pressure chan¬ ges, so as to make a maximal use of the amplitude corres¬ ponding with a specific wave movement. This vessel con¬ nects by means of a valve 6 with a compressor pump 7 and a bleeding valve 8. A piston rod 9 of the large piston 2 is directly and in particular coaxially coupled with a piston rod 10 of a small piston 11, the latter thus completely following the movements of the large piston 2. The rod 10 and the piston 11 form, together with a cylinder 12 with a front plate 13, a hydraulic cylinder of a known type. The liquid which is displaced by the piston 11 reaches a rectifying circuit 14 with a T-connector 15, and subsequently a one-way valve 16 connecting with an inlet tube 17 of a hydraulic displa- cement motor 18. This hydraulic motor is by way of example shown as a so-called Roots Blower, but any other known and in particular rotating hydraulic motor may be used in¬ stead. Furthermore a second large piston 19 is shown in Fig. 1, which is directly connected with a hydraulic piston 21, and which, furthermore, communicates in the same manner as the piston 9 and the hydraulic piston 11 with an accumula¬ ting vessel 5 and the hydraulic circuit 14. In the situation shown, the second large piston 19 is situated precisely below a wave valley 20, which piston is returned towards its highest position by the air pressure at its lower side. During its return movement the piston 21 has been moved upwards too, and then the liquid from the hydraulic motor 18 is sucked in by means of a one-way valve 22. After a phase shift of the heave wave all this is repeated in an inverse sequence. From a storage vessel 23 - in which also a driving gas 24 such as nitrogen is pre¬ sent - leak losses which may occur in the hydraulic cir- cuit 14 will be supplemented. A generator 25 which is directly coupled with the shaft of the hydraulic motor 18 generates electricity which, by means of a cable 26 (in particular a cable with a small resistance such as a superconductive cable) is transferred to a distribution or utilization point 27. The whole assembly mentioned above can be housed in a submarine engine room, the large pistons 9 and 19 being arranged in the roof thereof. Fig. 2 shows a top view of such an installation, in which a large number (45 in the case shown) of pistons 9 and 19 is present. This number is, of course, not to be considered in the restrictive sense. Fig. 3 shows a dia¬ grammatical lateral view of this installation. Such an installation can, for example, be housed in a concrete caisson which is constructed on the mainland and is transported floating on the water towards the site of use to be sunk there. It is also possible to provide cavities in the water bottom in which adapted cylinders are arranged. Such a submarine installation can, moreover, be connected with the mainland by means of a tunnel for obtaining access for repair and maintenance operations and for leading through the electric cables. It is also possible to accumulate, during periods of relative high wave motions, a portion of the wave and heave energy in the form of a compressed gas, and to transform this energy again into electrical energy during load peaks by means of a motor/generator assembly.

Claims: Claims 1. A hydro-pneumatic wave and heave power station for converting wave and heave energy into usable electrical energy, characterized in that, for utilizing the hydrosta¬ tic pressure difference of the amplitudes of wave tops and wave valleys with a continually shifting phase, two or more mutually co-operating but mechanically not coupled pistons with a relatively large diameter are used, which, during downward movement, use the pressure difference for directly driving hydraulic cylinders, which by means of a hydraulic rectifying circuit transfer their kinetic energy to a hydraulic motor coupled with an electrical generator, which pistons are returned again towards their highest position by means of a gas compressed during the downward stroke, which gas, after expansion, is still in equilibri¬ um with the water column above the piston, the generated electrical current being transferred by means of cables towards a utilization or distribution point on the main- land. 2. The power station according to claim 1, characterized in that the cylinder space below each large piston con¬ nects with an amply sized equalizing vessel. 3. The power station according to claim 1 or 2, charac- terized in that the large cylinders are movable in cavi¬ ties in the sea bottom acting as cylinders. 4. The power station of claim 1 or 2, characterized in that the large cylinders are movable in cylindrical cavi¬ ties in prefabricated concrete parts constructed as cais- sons lowered onto the water bottom, in which also other parts of this power station are situated. 5. The power station according to claim 1 or 2, charac¬ terized in that the complete power station is housed in a space arranged on or below the water bottom, which is connected with the mainland by means of a tunnel. 6. The power station according anyone of claims 1..5, characterized in that means are present for accumulating a portion of the wave and heave energy in the form of a compressed gas, during high wave motions, by means of which, as required, electrical energy can be generated by an assembly of a motor and a generator.

Inventors: BERG ARIE PIETER VAN DEN, LENTEN HENDRIK, VAN DEN BERG, ARIE, PIETER
Applicants: BERG A P VAN DEN BEHEER BV, BERG ARIE PIETER VAN DEN, A.P. VAN DEN BERG BEHEER B.V., VAN DEN BERG, ARIE, PIETER
Application year: 1997
Main classification: F03B13
IPC codes: F03B13