Wave Powered Generator

Abstract

A generator for capturing and converting wave energy into a more useful form is provided. The generator comprises: at least one energy capturing float (2) which is movable in response to wave motion; a reaction member (1) to be positioned below the energy capturing float; connecting lines (5a, 5b, 5c, 5d) for connecting the at least one energy capturing float to the reaction member and defining a spacing (D2) between the energy capturing float and the reaction member; energy convertors (6a, 6b, 6c, 6d) for converting relative movement between the reaction member and at least one respective energy capturing float to useful energy. The generator includes depth setting means such as adjustable mooring lines (3a, 3b, 3c, 3d) securing the reaction member to the sea bed SB for setting the depth (D1) of the reaction member in the sea. Both the float and the reaction member possess a positive buoyancy, allowing suitable tension to be applied to the mooring lines. The improved tension brought about by the net positive buoyancy has the surprising effect of improved stability in energetic sea conditions.

Claims

1. A generator for converting wave motion in a body of water to useful energy, the generator comprising: at least one energy capturing float which is movable in response to said wave motion; a reaction member to be positioned below the energy capturing float; connection means for connecting said at least one energy capturing float to said reaction member; energy conversion means for converting relative movement between said reaction member and said at least one respective energy capturing float to the useful energy; wherein the generator includes adaptable depth setting means for setting, over a predetermined range, the depth of the reaction member in the body of water and the height of the reaction member from a bed of the body of water, characterised in that both the float and the reaction member have a positive buoyancy.

2. A generator as claimed in claim 1, wherein the connecting means defines a distance between said energy capturing float and said reaction member.

3. A generator as claimed in claim 2, wherein the connection means are of adjustable length for independently adjusting the distance between the energy capturing float and the reaction member.

4. A generator as claimed in claim 1, claim 2, or claim 3, wherein the positive buoyancy of the float and the reaction member cause adequate tension in the depth setting means to provide stability to the reaction member when submerged.

5. A generator as claimed in claims 1 to 4, in which the connection means comprise at least one flexible line of adjustable length in which the length adjustment is achieved by winding the or each flexible line around a respective drum.

6. A generator as claimed in claims 1 to 5, in which the connection means are adjustably mounted to the reaction member such that the geometry of the connection means can be altered.

7. A generator as claimed in any one of claims 1 to 6, wherein the depth setting means comprise at least one flexible mooring line of adjustable length to adjustably position the reaction member above the bed of the body of water.

8. A generator as claimed in claim 7, wherein the generator has a net positive buoyancy that is resisted by tension of the at least one flexible mooring line.

9. A generator as claimed in any one of claims 1 to 8, wherein the depth setting means is coupled to the reaction member by a winch.

10. A generator as claimed in any one of claims 1 to 9, wherein at least one of: a. the reaction member length; b. the reaction member width; c. the reaction member diameter; is selected from the range 20 to 60 metres.

11. A generator as claimed in any one of claims 1 to 10, wherein at least one of: a. the float diameter; b. the float length; c. the float width; is selected from the range 10 to 20 metres.

12. A generator as claimed in any one of claims 1 to 11, wherein the separation between the float and the reaction member is selected from the range 0 to 50 metres.

Description

DETAILED DESCRIPTION

[0027] Specific embodiments will now be described by way of example only, and with reference to the accompanying drawings, in which:

[0028] FIG. 1 is a perspective view of a preferred embodiment of wave generator according to the invention when on the surface of a body of water (generally, the sea);

[0029] FIG. 2 is a perspective view of the wave generator of FIG. 1 when submerged beneath the surface of that body of water; and

[0030] FIG. 3 is an orthogonal view showing the energy convertor of FIG. 2 moored to the bed of the body of water.

[0031] Referring first to FIG. 1 and FIG. 2, there is shown an exemplary wave powered generator according to the invention which comprises a submersible subsea reaction member 1; an energy capturing float 2 that moves in response to the waves; a series of energy converters 6a, 6b, 6c, 6d mounted on the reaction member 1; and respective connecting lines 5a, 5b, 5c, 5d of adjustable length that connect the energy capturing float 2 to the respective energy converter 6a, 6b, 6c, 6d.

[0032] In FIG. 1, each of the connecting lines 5a, 5b, 5c, 5d is wound around a drum on the respective energy converter 6a, 6b, 6c, 6d to the fullest or maximum extent such that the spacing between the energy capturing float 2 and the reaction member 1 is at a minimum. In this case the reaction member 1 and the energy capturing float 2 are together floating on the surface S of a body of water.

[0033] Conversely, in the arrangement shown in FIG. 2, each of the connecting lines 5a, 5b, 5c, 5d is let out (wound around the respective drum) such that the spacing between the energy capturing float 2 and the reaction member 1 is at a maximum. In this case, the energy capturing float 2 is shown just below the surface S of the body of water.

[0034] FIG. 2 and FIG. 3 show the wave energy generator with mooring lines 3a, 3b, 3c, 3d which tether the generator to the seabed SB, thereby keeping the generator on station.

[0035] The mooring lines 3a, 3b, 3c, 3d may be connected to the reaction body 1 via corresponding length adjusting means 4a, 4b, 4c, 4d to enable the depth of submersion of the reaction member 1 to be varied.

[0036] It should be noted that in the first embodiment of the invention the mooring lines 3a, 3b, 3c, 3d remain tensioned at all times so that the generator cannot move freely up and down in the water column. The positive buoyancy of the reaction member 1 and the float 2, B2 and B1 respectively, enables the reaction member 1 to place upon the mooring lines 3a, 3b, 3c, 3d a tension Ta, Tb, Tc, Td, providing stability to the reaction member 1 and the float 2 in highly energetic sea conditions.

[0037] In the embodiment shown, the float has a radius R of 7.5 metres (diameter of 15 metres) and the reaction member has a length and width L of 40 metres. The separation from the float 1 and the reaction member 2 is a distance D2 of 30 metres. In this configuration the generator is arranged to perform optimally in an open sea environment.

[0038] The reaction member 1 is generally of a hollow construction and is adapted to be selectively filled with air or water to adjust its buoyancy. The wave powered generator according to the invention has a positive net buoyancy comprising the buoyancy of the reaction member 1, B2 and the buoyancy of the energy capturing float 2, B1. The generator has a permanent positive buoyancy, but may comprise a surface configuration as shown in FIG. 1 and a submerged configuration as shown in FIG. 2 and FIG. 3. The submerged configuration is the result of the mooring lines 3a, 3b, 3c, 3d used as a depth setting means.

[0039] When in the surface configuration (FIG. 1), the reaction member 1 floats on the surface S of the body of water (such as the sea) with sufficient buoyancy for it to carry all other components of the apparatus. In this condition the generator according to the invention can be readily disconnected from the mooring lines 3a, 3b, 3c, 3d and transported across the surface S of the body of water. The wave powered generator can sit sufficiently high in the water that all connections to mooring lines 3a, 3b, 3c, 3d and power umbilical 7 can be clear of the water and be easily accessible. The wave powered generator can also create its own stable service platform with all serviceable components clear of the water to enable easy access for maintenance.

[0040] With reference to FIG. 2, when the wave generator is in the submersed operating configuration, the buoyant reaction member 1 is held suspended by the combination of the energy capturing float 2 and the mooring lines 3a, 3b, 3c, 3d. The net buoyancy of the generator is defined by the sum of the buoyancy values of the reaction member 1 and the energy capturing float 2 (B1+B2).

[0041] The reaction member 1 has a large mass that resists movements caused to it by the forces applied by the float 2 via the connecting lines 5a, 5b, 5c, 5d, and by the forces applied to it directly by the waves. The reaction member 1 also has a large surface area perpendicular to the direction of the heave force, which thereby provides further resistance to movement by way of a large drag and added mass.

[0042] The reaction member 1 may be held suspended between the energy capturing float 2 and the seabed SB using the mooring lines 3a, 3b, 3c, 3d at a depth D1 sufficient to ensure that the reaction member 1 is generally below the influence of waves on the sea surface. Therefore movement of the energy capturing float 2 caused by waves results in relative motion between the energy capturing float 2 and the reaction member 1. This movement is taken up by respective working strokes of the energy converters 6a, 6b, 6c, 6d and thus exploited to produce power.

[0043] In the illustrated embodiment, a single float 2 is shown, but it will be understood that more than one such float can be provided if appropriate, each with its own series of energy converters mounted on the reaction member 1, together with respective connecting lines.

[0044] In the described embodiments, the float radius is shown as 7.5 metres (diameter 15 meters) and the length and width of the reaction member are shown as 40 metres. Alternative embodiments may comprise a float which can be of any shape with a diameter, or width and/or length, of between 10 metres and 20 metres. Alternative embodiments may also comprise a reaction member of any shape, with length and/or width, or diameter (where spherical), of between 20 metres and 40 metres.