WAVE ENERGY CONVERTER

Abstract

The present invention is a wave energy converter capable of extracting useful energy from ocean waves by utilizing finite depth of ocean waves, kinetic energy of flowing water and drag force of water that opposes the relative motion of the submerged body through the water, comprising two bodies attached to each other, wherein the buoyant body is moored to the seabed, and the fully submerged body is suspended from the buoyant body by vertical suspender cables, chains, ropes, other flexible lines, or a rigid frame, and placed at a depth of around one-half wavelength of the prevailing waves at the installation site, where the water is not affected by the surface wave action, therefore is still or relatively still.

Claims

1. A wave energy converter for converting the energy of ocean waves into electricity, comprising two bodies attached to each other, characterized in that the buoyant body is moored to the seabed, and the fully submerged body is suspended from the buoyant body by vertical suspender cables, chains, ropes, other flexible lines, or a rigid frame.

2. The fully submerged body according to claim 1, comprising at least one electric generator, at least one horizontally-aligned cylindrical rotor, at least one flywheel and at least one overrunning clutch, characterized in that, the submerged body is placed at a depth where the water is not affected by the waves, therefore is relatively still.

3. The fully submerged body according to claims 1 and 2, characterized in that the rotor and the generator are so placed and connected to each other within the submerged body that rotation of the rotor is transferred to the generator either directly or through a gear.

4. The rotor according to claim 2, characterized in that a plurality of variable geometry scoop-shaped buckets is attached to a lateral surface of the rotor, and are tangentially and unidirectionally placed around the rotor, and evenly spread across the lateral surface of the rotor.

5. The rotor according to claim 2, characterized in that the rotor has a modular, foldable inner frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale. Emphasis instead being placed upon illustrating the principles of the invention.

[0030] FIG. 1 is a schematic drawing of the wave energy converter in operation, moving upward.

[0031] FIG. 2 is a schematic drawing of the wave energy converter, moving downward.

[0032] FIG. 3 is a perspective view of the rotor parts.

[0033] FIG. 4 is a perspective view of the lateral surface of the rotor with an integrated plurality of buckets.

DETAILED DESCRIPTION OF THE INVENTION

[0034] The motion of water beneath the surface decreases exponentially with depth. Ocean waves have only a finite depth. No matter how significant is a wave action on the water surface, at the same time the water at a certain depth is calm. In general, the wave power below sea level decays exponentially by −2πd/L where d is the depth below sea level, and L is a wavelength. This property is valid for waves in deep water with depths greater than L/2 i.e. ocean.

[0035] The wave energy converter 1 comprises two bodies attached to each other. The buoyant body 2 is moored to the seabed. Suspended from the buoyant body by vertical suspender cables, chains, ropes, other flexible lines 3, or alternatively using a rigid frame, is a fully submerged body 4, comprising at least one horizontally-aligned modular, preferably frame-foldable cylindrical rotor 5 with a plurality of variable geometry scoop-shaped made of a flexible or otherwise elastic material buckets 6, tangentially and unidirectionally attached to a lateral surface of the rotor, at least one electric generator 7, equipped with a flywheel 8 and an overrunning clutch 9, ensuring smooth and consistent rotation of the generator (FIG. 1).

[0036] The buoyant body 2, is moored to the seabed by mooring cables 11, and is so shaped to provide minimum resistance to the passing waves. The said buoyant body is preferably of modular design, comprising a plurality of smaller buoyant modules attached to each other, thus improving survivability, transportability and reducing transportation cost.

[0037] The rotor 5 transfers rotation to the generator 7 directly, or through the gear 10 or another rotation transferring system.

[0038] In order to fully utilize the energy of passing ocean waves, the submerged body 4 is placed at a depth where the water is not affected by the waves, therefore is still or relatively still. Preferably, the submerged body 4 is placed at a depth of around one-half wavelength of the prevailing waves at the installation site.

[0039] As a wave rises (FIG. 1), the buoyant body 2 moves upward, dragging the attached submerged body 4 upward through the region of stationary water until the wave reaches its crest. The suspender cables (chains, ropes or other flexible lines) 3 are under constant tension due to multiple opposing forces i.e. buoyancy, gravity, drag.

[0040] The water resistance (drag) opposes the relative motion of the submerged body 4 with the installed rotor 5 through the water. Drag forces act in a direction opposite to the oncoming flow velocity.

[0041] Each variable geometry scoop-shaped bucket 6 is so shaped to provide maximum resistance to the oncoming relative water flow at its open end, and minimum resistance at its opposite closed end.

[0042] All buckets 6 attached to the rotor 5 are placed unidirectionally, thus their open ends face the same direction. As a result, the rotor 5 will always turn in the same direction, regardless of the direction of the movement of the submerged body 4 to which it is subjected by the movements of the buoyant body 2 under the influence of the passing waves.

[0043] This motion of the submerged body 4 through a region of stationary water causes rotation of the rotor 5. Thus, with the buckets 6 arranged as shown in (FIG. 1), it is evident that, as the rotor moves upward through water, the buckets on the left side of the rotor provide greater resistance to the relative flow of water than the closed buckets on the right side of the rotor. Drag coefficient of the bucket's closed end, that is shaped as a streamlined half-body (scoop, half-cone), is around 0.06. Drag coefficient of the bucket's open end, that is approximately shaped as a hollow half-sphere, is around 2.0. Due to a significant difference in drag forces applied to the open and closed ends of the bucket 6 on the opposite sides of the rotor 5, it results in a counterclockwise rotation of the rotor 5.

[0044] As a wave falls, (FIG. 2), the buoyant body 2 moves downward, the attached submerged body 4 is dragged downward through the region of stationary water by the force of gravity until the wave reaches its trough, opening the buckets 6 on the right side of the rotor 5, thus providing greater resistance to the relative water flow, than the buckets 6 on the left side of the rotor 5, forcing the rotor continue rotating counterclockwise.

[0045] This continuous unidirectional rotation of the rotor 5 with the attached variable geometry buckets 6 is transmitted by the gear 10, as shown in (FIG. 1) and (FIG. 2), to the electric generator 7, and is converted into a usable form of energy, electricity.

[0046] Alternatively, the said rotation of the rotor 5 through the gear 10 could drive a hydraulic pump or air compressor or any other energy converting device.

[0047] (FIG. 3) shows the said rotor, comprising a modular, preferably foldable frame 12 and a securely attached to it lateral surface 13 with buckets 6. In the preferred embodiment the lateral surface 13 is fabricated as a single element integrated with a plurality of buckets 6 made of a flexible or otherwise elastic material (FIG. 4).

[0048] Alternatively, the said lateral surface consists of a plurality of flexible, semi-flexible or rigid surface elements 14 securely attached to the frame, wherein, the said buckets 6 can be securely attached to the said elements 12 (FIG. 3).

[0049] The preceding detailed description is not intended to be limited to the specific embodiments set forth herein, but on the contrary, the description is intended to be exemplary, and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.