GB2445755A

GB2445755A - Ocean current power generator

Info

Publication number: GB2445755A
Application number: GB0701130A
Authority: GB
Inventors: Douglas Kitchener Gatward
Original assignee: OCEAN POWER GENERATION Ltd
Current assignee: OCEAN POWER GENERATION Ltd
Priority date: 2007-01-19
Filing date: 2007-01-19
Publication date: 2008-07-23
Also published as: GB0701130D0

Abstract

Electrical generation apparatus comprises a mounting arrangement to stably support first and second hydroelectric converters 34. Each hydroelectric converter is operable to engage with an ocean current to convert energy from the ocean current into electrical energy. The first and second hydroelectric converters are independently mounted on the mounting arrangement, such that the first and second hydroelectric converter can engage with different ocean currents.

Description

* 2445755 M&C Folio: GBP96719 Document:1226055

OCEAN CURRENT POWER GENERATOR

The present invention concerns a generator of electrical power, operable to convert energy stored in a flow in a large body of fluid, to electrical energy.

It is becoming increasingly the case that diverse sources of energy are being sought to satisfy demand for electrical power. Although wind and solar power have been successfully incorporated into commercial operations, there is a growing appreciation that energy bound in ocean currents (occasionally known as hydrokinetic energy) could also be harnessed.

In common with all electricity generation equipment, there is a need to provide ocean power generation equipment with increased efficiency. This is partly because the cost of installation may be extremely high, and so the output of such an installation must be maximised.

Various existing technologies have been proposed, each of which provides a relatively small installation, useful for coastal areas. However, these do not make use of the potential energy bound up in massive ocean currents, which cannot be harnessed by conventional installation.

For instance, a proposal by IT Power, as identified at www.itpower.co.uk/OceanEnergy.htm provides a possible technology for tidal stream andlor wave energy, in certain near-shore locations. These rely on geographic phenomena to provide a suitable water flow, which may have an impact on the coastal environment.

A helical turbine has also been developed, built into arrays as described in International Patent Application W096/3 8667, by Alexander Gorlov. This latter approach has the advantage that it can, in theory, be classed as multidirectional, although substantial reconfiguration would be needed in practice if the direction of water flow were to change. This is because the helical turbines must remain relatively small for structural reasons, and the resultant arrays would need to be physically manoeuvred into a new orientation to take account of a change in current direction.

An aspect of the present invention comprises electrical generation apparatus operable to be installed on a seabed, comprising first and second hydroelectric conversion means, each hydroelectric conversion means being operable to engage with an ocean current to convert energy from said ocean current into electrical energy, and wherein the first and second hydroelectric conversion means are independently mounted on mounting means, such that said first and second hydroelectric conversion means can engage with different ocean currents.

Another aspect of the invention provides apparatus for converting hydrokinetic energy into electrical energy, comprising a frame and upper and lower hydroelectric conversion means arranged on the frame to engage with fluid flow at respectively upper and lower depths.

It is an advantage of this arrangement that it can harness energy resultant from varied flows impinging on the apparatus. For instance, it is understood that marine currents can be stratified, with shallow level currents of relatively warm water flowing in one direction past a given point, and deeper level currents of relatively cold water flowing in a completely different direction. The first and second hydroelectric conversion means can be directed respectively at the higher and lower level currents. Another advantage of appointing the apparatus of the invention in a body of water having substantially opposed deep-and shallow-water currents is that shear stresses applied to the frame, if it is fixed to a bed, can at least in part be counterbalanced.

By controlling the extent to which the respective hydroelectric conversion means are engaged with the flows, the stresses on the frame can be substantially counterbalanced.

Further, in a case wherein the frame is not fixed to a bed, and flotation means are provided to cause the apparatus to be buoyant, the counterbalancing of the forces on the frame brought about by increasing or reducing the loading on the respective hydroelectric conversion means can be used to maintain the location of the apparatus in the body of water concerned, or indeed to move the location if desired.

Aspects of the invention provide an opportunity to harness marine current energy not just at ocean surface, but wherever the most effective energy source can be identified.

Moreover, it takes advantage of the opposing forces that may exist in marine current flow, between surface flow (which may be the result of bulk flow of warmed water, or prevailing winds) and deep water flow (such as bulk flow of colder water). This is counter to existing approaches which is to harness only the best option (usually the surface flow) and to ignore or isolate other, potentially opposing flows.

The mounting means may be engageable with a geographic structure, such as the sea bed. In an alternative embodiment, they may mount to one or more pontoons, or other flotation devices, to achieve the same end result.

Preferably, the first and second hydroelectric conversion means are appointed one above the other, such that one can engage with a surface adjacent ocean current and the other can engage with a deeper water ocean current.

An array of such apparatus can be provided, such as to cover a wider extent of ocean than may be possible with one device.

Specific features and advantages of the invention will be appreciated from the following description of a specific embodiment of the invention. This specific embodiment is provided by way of example only, and should not be considered as limitation on the scope of the invention for which protection is sought. The specific embodiment is illustrated in the appended figures, in which: Figure 1 is a side elevation of an ocean current electrical conversion rig in accordance with the specific embodiment of the invention; Figure 2 is a plan view of a generation platter of the rig illustrated in Figure 1; and Figure 3 is a side elcvation, similar to Figure 1, of the rig in an alternative configuration.

The ocean current electrical generation rig 10 illustrated in Figure 1 is of substantially similar construction, in structural tenns to an oil rig. In fact, the present invention provides for installation of the active components of the specific embodiment into an oil rig, whether disused or still active. The rig 10 comprises four piles 20, each of which is made up of two telescopic sections which allow raising and lowering of items suspended from the piles 20. The raising and lowering is indicated by the double headed arrows in Figure 1. The piles are embedded in the seabed by means of feet 22.

An operation platform 24 is indicated as suspended from the piles 20 above the sea level.

First and second generation platforms 30, 32 are ftilly suspended from the piles 20. In this embodiment, the first generation platform 30 is suspended from the piles such that its extremities can move upwards or downwards under independent control. This could be provided in use by means of hydraulic means. Located on each generation platform is a plurality of hydroelectric turbine generators 34. These are aligned to capture ocean going currents imposed upon the apparatus 10.

In use, the first and second generation platforms 30, 32 can be independently oriented.

This allows for the fact that ocean going currents are commonly stratified. That is, a surface layer of warm water may be travelling a very different direction from a deep level layer of cold water. One example of this is in the Northern Atlantic, where the Gulf Stream flows in a generally north easterly direction, while a flow of cold water flows in a southerly direction from the Artic to the Caribbean. By suitable placement of the apparatus 10, the incidence of two major currents on the apparatus can be maximised.

Figure 2 illustrates in further detail the structure of the first generation platform 30. The mounting of the platform 30 on the piles 20 is illustrated schematically, although it will be appreciated that some form of mechanical linkage will be required, to provide for the tilting mechanism described above.

In this case, an array of three hydroelectric turbine generators is provided. The platform comprises an outer bezel 36 and an inner platter 38. The inner platter is rotatable (by drive means not illustrated for reasons of clarity), to allow the turbine generators 34 to be directed towards the incident current.

It will be appreciated that, instead of a driver to drive the platter 38 to the correct orientation, the platter may be fitted with one or more fins operable to engage with an impinging marine current so as to cause a moment to be applied to the platter 38 to bring the turbine generators 34 into alignment with the flow. Suitable damping means may be provided to reduce the impact of oscillation about the equilibrium orientation.

As illustrated in Figure 3, the first platform at least can be tilted by means of the independent mounting of the platform on the pile 20, to allow full advantage to be taken of the angle of incidence of the ocean current. It is known that ocean currents are not necessarily oriented in the horizontal, and can be oriented an angle to the horizontal in certain circumstances. The illustrated orientation is an exaggeration of the likely angles from the horizontal which will be experienced in practice, but is shown as such for reasons of clarity. To maximise the possible efficiency of such a device, the tilt provides additional opportunity to capture energy from the ocean current.

The specific embodiment is advantageous as it takes advantage of existing anchoring technology used in the oil and gas industries. It is thus possible to use an implementation of the invention in ways which do not have a great environmental or societal impact. Use of such technologies also aids in construction, location and relocation of a rig in accordance with the specific embodiment. Relocation is a significant consideration, as marine current flows are subject to change, and the existing technologies which allow relocation of an oil rig can equally be applied to the present implementation of the invention.

Power generated by the hydroelectric elements can either be consumed on site (which may be of substantial interest to an off shore natural resource extraction operation) or transported by cable (or by other, wireless means) to an on shore location for transmission to consumers.

One possible use of the generated power is in the extraction of hydrogen, by any process harnessing the use of electricity. This hydrogen may be a more conveniently transportable energy resource than the generated electrical power, especially if the rig is very remotely off shore. Another approach would be to charge fuel cells on site, for use off site.

Moreover, the rig could be used as a residence or industrial location, for enhanced use of resources. In an industrial example, the site could be a useable source of non-carbon emissive energy for use by industry.

Claims

CLAIMS: 1. Electrical generation apparatus comprising mounting means

and first and second hydroelectric conversion means, each hydroelectric conversion means being operable to engage with an ocean current to convert energy from said ocean current into electrical energy, and wherein the first and second hydroelectric conversion means are mounted on said mounting means, such that said first and second hydroelectric conversion means can engage with different ocean currents.
2. Apparatus in accordance with claim 1 wherein the first and second hydroelectric conversion means can be directed respectively at higher and lower level currents.
3. Apparatus in accordance with claim I or claim 2, wherein each said hydroelectric conversion means is operable to generate electricity on the basis of a primary flow direction, and wherein each said hydroelectric conversion means is redirectable at said primary flow direction.
4. Apparatus in accordance with claim 3 wherein each said hydroelectric conversion means comprises a support means rotatable with respect to said mounting means, and turboelectric generator means mounted on said support means.
5. Apparatus in accordance with any preceding claim wherein the mounting means is engageable with a geographic structure, such as the sea bed.
6. Apparatus in accordance with any of claims I to 5 wherein said mounting means comprises one or more flotation means.
7. Apparatus in accordance with claim 6 wherein said flotation means comprises one or more pontoons
8. Apparatus in accordance with any preceding claim wherein the first and second hydroelectric conversion means are appointed one above the other, such that one can engage with a surface adjacent ocean current and the other can engage with a deeper water ocean current.
9. A method of generating electricity including employing apparatus in accordance with any preceding claim, placing said apparatus in a marine current flow, and drawing off an electrical potential for electricity supply.
10. Electricity generated by a method in accordance with claim 9.
11. A method of generating a combustible fuel by generating electricity in accordance with claim 9, and electrolysing a chemical compound to generate at least one combustible product of said electrolysis.
12. A combustible fuel generated in accordance with claim 11.
13. A fuel cell charged by means of electricity in accordance with claim 10.
14. Apparatus as described herein, with reference to the accompanying drawings.
15. A method of generating electricity as described herein, with reference to the accompanying drawings.