Wave energy converter

Details Wave energy converter Wave energy converter

1999-06-07

2001-02-27

Enad, Elvin (Department: 2834)

Prime-mover dynamo plants

Tide and wave motors

C290S042000, C290S043000, C290S054000

Reexamination Certificate

active

06194791

ABSTRACT:

The present invention relates to a structure for collecting waves, with the intention of transforming wave energy into electrical or another readily utilisable form of energy.
Since the 1970's there has been increasing concern about the earth's finite fossil fuel resource and about environmental pollution resulting from combustion of such fuels. This has led to considerable efforts to develop new and cost-effective means of obtaining energy from renewable sources. In particular, there has been much interest in how to derive usable energy from solar, geothermal, wind and wave sources. The latter two offer the prospect of generating electricity by directly converting the kinetic energy of wind or waves into electrical energy.
Theoretically, waves constitute an enormous reservoir of energy to be exploited. However, the random nature and the hostility of the marine environment pose significant problems to the practical realisation of a cost-effective wave-to-electricity energy converter.
Although deep water offers the largest incident power flows, it has been realised that the mass, rigidity and complex engineering necessary to enable the equipment to survive in that environment makes it uneconomic. Another reason is that deep water structures must float and this reduces the conversion efficiency.
It is now known that a depth of about 10 fathoms is about optimum. Although incident power flows reduce with decreasing depth, so do construction, installation and operating costs.
The applicants have previously filed International patent application No. PCT/GB92/00711, published as WO 92/18704. This describes a number of different configurations of deep-water wave collectors/generators.
Another proposal for a design of collector is shown in
FIG. 1
of the accompanying drawings. This structure
1
comprises a collector
3
comprising a base
5
, a rear wall
7
, a top wall
9
and a lip
11
which depends vertically downwards from the upper wall
9
. The lower edge
13
of the lip
11
protrudes below the level
15
of the incident waves
17
.
In the structure shown in
FIG. 1
, the space below the lower edge
13
of the lip
11
defines a mouth
19
through which the water enters. The space
21
above the waves
17
, within the collector
3
, is extended by means of a chimney or duct
23
, which under influence of the wave action, behaves as an air column of oscillating pressure to drive a self-rectifying turbine
25
connected to an electrical generator
27
. The turbine
25
and generator
27
are located in the upper part
29
of the duct
23
, just below an air outlet
31
.
The collector
3
also comprises side walls
33
etc. (as shown in FIG.
1
), parallel to the plane of the paper but respectively above and below the plane of the paper. The side walls extend to a point
35
forward of the lip
11
and up to the level
35
of the upper surface
9
of the collector. This has been found to aid efficiency of conversion of wave power to electrical energy.
Another known arrangement is shown in
FIG. 2
of the accompanying drawings. This comprises a structure
41
comprising a generally scoop-shaped collector
43
with a flat upper wall
45
and a vertically downwardly depending lip
47
. It can be seen that this is generally analogous to the structure shown in
FIG. 1
, except that the shape of the collector
43
generally resembles a “C” shape but with a flattened top and a vertically downwardly depending lip.
Whilst all of the aforementioned known proposals represent significant advances in the development of a practical wave-to-electricity energy converter, in practice it is quite difficult to design a shape of wave collector structure which is efficient in converting wave energy to electrical energy, sufficiently buoyant and stable to be floated to the off-shore site and yet which can be safely anchored to the sea bed in such a way as to be able to withstand the strongest waves which are encountered perhaps once only in fifty years.
A new form of structure has now been devised capable of fulfilling these stringent criteria. This embodies a number of inventive concepts.
Thus, a first aspect of the present invention provides a wave collector structure for an electrical power generator powered by wave energy, the structure having an outwardly extending and downwardly depending lip below which is situated a mouth of the collector, the collector further comprising a pair of side walls for channelling waves into the collector mouth, the side walls extending horizontally, substantially up to or beyond the lip for enclosing partially, a volume of water between the lip and side walls.
Thus, in the kind of structure according to the first aspect of the present invention, the two side walls define the extent of the partially enclosed volume of water in one direction. The outwardly extending and downwardly depending lip effectively defines the rear and lower extent of the partially enclosed volume. This has been found to enhance the efficiency of conversion, in comparison with the corresponding design with a vertically descending lip as shown in
FIG. 1
or FIG.
2
.
The lip can take on a number of configurations, for example substantially flat (but sloping) or curved, preferably with a convex curvature as viewed from the exterior of the structure.
In a preferred embodiment, the side walls respectively flank the wave collector at either side of the mouth and may be integral with the outermost edges of the mouth.
The collector may comprise a plurality of tubular collector chambers, each having an outwardly extending and downwardly depending lip part below which is situated a mouth part. The collector chambers may have a rectangular, square or circular cross-section, the mouth parts being rectangular, square or C-shaped.
This chamber profile is differentiated from that of the prior art arrangement as shown in
FIGS. 1 and 2
. The lip parts of the chambers extend in a forward and downward depending fashion, rather than as a vertically descending lip. This arrangement has been found to confer additional advantage in performance terms over the prior art arrangements. In practice, the collector according to the present invention will usually be flanked by a pair of side walls. The side walls also serve to enhance collection efficiency.
Preferably, as in the preferred embodiment, the side walls extend beyond the lip defined by the upper surface of the collector chambers to enclose partially, a volume of water between the lip and the side walls.
A second inventive feature provided by the present invention involves the placing in a desired location of the collector described above. Thus, a second aspect of the present invention provides a wave collector structure for an electric power generator powered by wave energy, the structure having an inlet for the ingress of waves and valve means for sealing the inlet to enable the structure to be floated to a desired location whereupon the valve means is opened to allow water to enter and allow the structure to sink.
The wave collector of the second aspect of the present invention may have any of those features described above, wherein the collector mouth would be sealed by gate means which would be removed once the structure had submerged.
The structure/collector according to the invention may be anchored by means of an elongate member extending into the sea bed from a lower part thereof.
In use, oscillations of the water surface within the collector cause corresponding pressure changes in the air above the surface, constrained within the upper part of the collector. These pressure changes can be ducted to a rotor used to drive a generator of electricity, i.e. a dynamo or alternator device. They can also be used to transmit power to the land in hydraulic form. However, it will be appreciated that in the broadest, the present invention comprises the collector or collector structure per se.
Preferably, such a rotor as referred to above is a self-rectifying turbine. This means, a rotor which turns in the same direction, regardless of which direction

Affiliated with

Also associated with

Rating

Wave energy converter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Wave energy converter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Wave energy converter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2615424