WO2009143580A1

WO2009143580A1 - Electrical power generator

Info

Publication number: WO2009143580A1
Application number: PCT/AU2009/000674
Authority: WO
Inventors: Peter Biggs
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-05-30
Filing date: 2009-05-29
Publication date: 2009-12-03
Anticipated expiration: 2010-11-30
Also published as: AU2009253747A1

Abstract

An electrical power generator (1) is disclosed. The generator (1) has a stator (2) having a surface (4). The generator (1) also has a rotator arm (18) having an end (12) located adjacent to the surface (4). The generator (1) has a rotor axis (8) around which the arm (18) is arranged to rotate. The arm (18) is arranged for the end (12) to move away from the axis (8) during increasing arm rotation and move towards the axis (8) on decreasing arm rotation. The electrical power generator (1) may be used as part of a wind generator, for example.

Description

ELECTRICAL POWER GENERATOR

Field of the Invention

The present invention generally relates to electrical power generators, and particularly but not exclusively to wind generators .

Background of the Invention

Climate change and the increasing costs of generating electrical power have invigorated interest in power generation using renewable energy sources. One of the more promising sources of renewable energy is from the movement of air such as wind.

Current electrical generators harnessing wind power tend to be complicated, require significant wind speeds and have potentially dangerous or inconvenient blades.

Climate change has prompted the introduction of various carbon emission trading schemes. It is expected that these trading schemes will in their own right be profitable .

Summary of Invention

According to a first aspect of the invention there is provided an electrical power generator comprising: a stator having a surface; a rotor arm having an end located adjacent to the surface; a rotor axis around which the arm is arranged to rotate; the arm being arranged for the end to move away from the axis during increasing arm rotation and move towards the axis on decreasing arm rotation. In an embodiment, the surface is a curved surface.

In an embodiment, the arm is arranged for the end to swing away from the axis during increasing arm rotation and swing towards the axis on decreasing arm rotation. The end of the rotor arm may comprise one or more magnets.

In an embodiment, the arm is connected to a rotary shaft. The shaft may define the axis.

In an embodiment, the stator may comprise an armature. The stator may comprise one or more electrical conductors running adjacent the curved surface and perpendicular to the rotor arm. The electrical conductors may be traced out by the end when the arm is swung away from the axis but the arm is not rotating. Each of the one or more electrical conductors may be separated from the surface by a magnet .

In an embodiment, the curved surface is an inside hemispherical surface internal of the stator. The hemispherical surface may be capped by a capping member. The rotary shaft may pass through an aperture formed in the capping member. The shaft may be supported by one or more rotary and/or thrust bearings coupled to the capping member .

In an embodiment, the stator comprises a plurality of stacked plates. Each of the plates may be generally orthogonal to the axis. The stator may comprise a laminate . The plates may be separated from each other by an insulating layer. The laminate may advantageously reduce eddy currents.

According to a second aspect of the invention there is provided a wind generator comprising: an electrical power generator defined by the first aspect ; and a wind turbine coupled to the electrical power generator to drive it .

In one embodiment, the wind turbine is mechanically coupled to the electrical power generator. Alternatively, the wind turbine is magnetically coupled to the electrical power generator.

In an embodiment, the wind generator is attached to a structure. The structure may be either a purpose built structure or a non-purpose built structure.

The structure may comprise a building. The building may be a pre-existing building adapted for attachment to the wind generator.

Alternatively, the structure may comprise a pole. The pole may comprise a power line pole. The wind generator may be located adjacent a top end of the pole when the pole is erect.

According to a third aspect of the invention there is provided a device for generating electrical power, the device comprising: an electrical power generator defined by the first aspect ; and a turbine coupled to the electrical power generator to drive it and arranged to capture the kinetic energy of air from an air exhaust .

In one embodiment, the turbine is mechanically coupled to the electrical power generator.

In an embodiment, the electrical power generator is defined by the first aspect of the invention. In an embodiment, the air exhaust is a structure air exhaust. The structure may be a building. The structure may be a wind generator supporting structure arranged to provide convective currents for driving the turbine.

According to a fourth aspect of the invention there is provided a method of creating a financial instrument tradable under a greenhouse gas Emissions Trading Scheme (ETS) , the method comprising the step of exploiting an electrical power generator defined by the first aspect of the invention.

According to a fifth aspect of the invention there is provided a method of creating a financial instrument tradable under a greenhouse gas Emissions Trading Scheme

(ETS) , the method comprising the step of exploiting a wind generator defined by the second aspect of the invention.

In an embodiment, the financial instrument comprises one of either a carbon credit, carbon offset or renewable energy certificate.

According to a sixth aspect of the invention there is provided a method of creating a feed-in tariff, the method comprising the step of exploiting an electrical power generator defined by the first aspect of the invention.

According to a seventh aspect of the invention there is provided a method of creating a feed-in tariff, the method comprising the step of exploiting a wind generator defined by the second aspect of the invention.

According to a eighth aspect of the invention there is provided a method of creating a feed-in tariff, the method comprising the step of exploiting a device for generating electrical power defined by the third aspect of the invention. According to a ninth aspect of the invention there is provided a method of creating a financial instrument tradable under a greenhouse gas Emissions Trading Scheme (ETS) , the method comprising the step of exploiting a device for generating electrical power defined by the third aspect of the invention.

Brief description of the Figures

In order to achieve a better understanding of the nature of the present invention embodiments will now be described, by way of example only, with reference to the accompanying figures in which: Figure 1 shows an elevational view of one embodiment of an electrical power generator suitable for harnessing wind power;

Figure 2 shows a plan view of the electrical power generator of Figure 1 ; Figure 3 shows a perspective view of a cross sectioned generator of Figure 1;

Figure 4 shows a perspective view of cross sectioned generator of another embodiment ; and

Figures 5 and 6 show embodiments of a wind turbine fixed to a building and pole respectfully.

Detailed Description of embodiments of the invention

Figure 1 shows a cross section through one embodiment of an electrical power generator generally indicated by the numeral 1. The generator has a stator 2 having a curved surface 4 internal of the stator 2. In this embodiment, the internal surface 4 is hemispherical but it may be any suitable geometry. The hemisphere may have an aperture at its pole for magnetic field lines or mechanical structures to pass therethrough. The generator has a pair of rotor arms 16,18. The arms 16,18 are arranged to rotate around an axis 8. Each of the rotor arms 16 has a pair of opposing ends 10,12 which are respectively proximal and distal to the axis 8. The proximal end 10 is attached to a rotor shaft 6 via a pivot such as 14. The shaft 6 in this embodiment defines the rotor axis 8. The shaft 6 also rotates around the axis 8. Mechanical power drives the shaft, for example from a wind turbine coupled to it, which in turn rotates the arms, The distal end 12 is located adjacent to the curved surface 4. The distal end has one or more magnets 20 attached to it . The magnets may be either permanent or electromagnets. The electromagnets may be powered by the generator 1 itself.

The pivots 14 allows the arms 16,18 to move away from the axis 8 during increasing arm rotation and move towards the axis 8 on decreasing arm rotation. In this embodiment, the arm movement is a swinging movement indicated by the arrows 24. Figure 1 shows in solid lines the arms 16,18 partly swung out. The arms swung in 22, for a non rotating rotor, are shown in phantom.

It will be appreciated that the moment of inertia, and thus the amount of power required to accelerate the rotor 9 (comprising the rotor shaft 6 and the arms 16,18) changes as the arms 16,18 move away from the axis 8. Thus, when the rotor 9 is starting to rotate there is relatively little rotational inertia to be overcome, and thus the rotor requires little effort to start rotating. But as the rotor speeds up more power is needed to accelerate the rotor. This is advantageous in many circumstances because it provides an adaptable generator. If wind blades are mechanically coupled to the electrical power generator to drive it, the rotor will start rotating in wind speeds that may not be sufficient for the rotor of other generators to start rotating. At higher wind speeds, however, the arms 16,18 move away from the axis 8 to provide a generator suitable for higher wind speeds .

In one embodiment, the wind blades 56 (which may be aerofoils) rotate around the vertical axis 8. As shown in Figure 5, the blades may, for example, comprise a whirlybird type roof ventilator attached to a building 58 by struts 60, in which case the kinetic energy of the air traveling through an air vent 64 or exhaust is converted into electrical power by the generator 1. Of course, the blades may be of any suitable arrangement or type, such as Danrieus, Giromill, Savonius configurations for example. Many of these systems could be installed on an existing or pre-existing structure, a power pole or a roof of a shed, house or other building, for example, and the power used locally or feed into a grid. If the power is used locally, power transmission losses are greatly reduced. The structure may be adapted for the wind generator to be attached thereto, by way of recessed bolt holes, beams, etc, for example. Figure 6 shows a pole 50, which may be any type of suitable pole including a power or transmission line pole or light pole, for example, sunk into the ground 52 with one embodiment of the wind generator 53 attached thereto by way of guy wires 54.

The stator 2 is the armature of the generator 1. As shown in figure 3, electrical conductors such as 26 run adjacent the curved surface 4 and perpendicular to the rotor arms 16,18. The electrical conductors 26 are traced out by the end 12 when the arm is swung away from the axis 8, indicated by arrows 24, but the shaft 6 is not rotating. The conductors may comprise, for example, a wire, ribbon or sold mass. Each of the electrical conductors 26 is, in this particular embodiment, backed by a magnet 28 but they need not be in every embodiment. In this embodiment, there are a plurality of such magnets, the magnets 28 being arcuate and arranged in a rib formation. The magnets 28 line the surface 4, although in some embodiments the surface may be a collective surface of a plurality of magnets or a single hemispheric magnet.

Figure 4 shows a cross section of another embodiment of a generator in which identical or similar parts are similarly numbered. In this embodiment, the stator 2 is of a laminate construction. It has a plurality of stacked plates such as 40, 42. Although only a few layers are shown it will be appreciated that the stator may be substantially completed laminated. A thin insulating sheet 44 may separate each of the plates from an adjacent plate which may advantageously reduce eddy currents. The plates are, in this embodiment, orthogonal to the axis 8. Conductors such as 28 run from a pole 46 generally upwards. In this embodiment, the conductor 28 is inset within the wall 48 of the stator 2, and has a generally ovoid cross section. The conductor may be a single solid piece or divided into sub-conductors or even wires. The conductor 28 width may increase with its depth in the wall 48 but need not. This may improve interaction with the magnetic fields which weaken with distance from the magnets 20 located adjacent the distal end of the arms 12 and 16. The stator 2 and hemispherical surface 4 may be capped by a capping member 30. The rotary shaft 6 passes through an aperture 32 formed in the capping member 30. The shaft 6 is supported by one or more rotary and/or thrust bearings 34 coupled to the capping member 30.

The wind generator may be located on top a supporting structure such as a pole. The pole may be an existing pole or a purpose built one. For example, the pole may be 600mm in diameter and 10m high. In some embodiments, a sheet metal (or other membrane) is wrapped around the pole to create an annular passageway extending longitudinally and upwards towards the wind turbine, terminating at an air exhaust below the blades. When exposed to sunlight, the sheet metal heats up creating an upward draft of air for powering the blades and thus the generator. The sheet metal may be finished in a dark color to promote its heating.

A financial instrument tradable under a greenhouse gas Emissions Trading Scheme (ETS) may be created by exploitation of the electrical power generator 1 powered by a renewable energy source, such as wind. The instrument may be, for example, one of either a carbon credit, carbon offset or renewable energy certificate.

Generally, such instruments are tradable on a market that is arranged to discourage greenhouse gas emission through a cap and trade approach, in which total emissions are •capped¹, permits are allocated up to the cap, and trading is allowed to let the market find the cheapest way to meet any necessary emission reductions. The Kyoto Protocol and the European Union ETS are both based on this approach. One example of how credits may be generated by using the generator 1 follows. A person in an industrialised country wishes to get credits from a Clean Development Mechanism (CDM) project, under the European ETS. The person contributes to the establishment of a wind farm incorporating one or more of the generators 1 coupled to suitable wind turbine blades. Credits (or Certified Emission Reduction Units where each unit is equivalent to the reduction of one metric tonne of C02 or its equivalent) may then be issued to the person. The number of CERs issued is based on the monitored difference between the baseline and the actual emissions. It is expected by the applicant that offsets or credits of a similar nature to CERs will be soon available to persons investing in low carbon emission energy generation in industrialised nations, and these could be similarly generated. For example, the generator coupled to the roof ventilator described herein may generate credits.

Alternatively, a feed- in tariff may be generated by using the electrical power generator 1 powered by a renewable energy source, and feeding the power thus generated back into a grid.

Now that embodiments have been described, it will be appreciated that some embodiments may have some of the following advantages:

• the generator may generate electricity at a relatively low wind speed;

• the generator is suitable to be driven by both relatively low and relatively high mechanical powers;

• the generator is able to generate at relatively high speeds without incurring structural damage as the generator adapts to these higher powers; • the generator is relatively simple and may require little or no maintenance over large periods of time;

• carbon credits or feed in tariffs may be generated; and • complicated gear boxes, commonly associated with wind generators, are avoided.

• The generator is suitable for local use, minimizing power transmission loss.

It will be appreciated that numerous variations and/or modifications may be made to the embodiments shown and described. For example, the density or strength of magnets on the stator may increase as the arm swings up. The hemisphere rather than the arms may rotate. The surface may be perforated, mesh-like or formed by separated magnets or a single magnet. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

Claims

" Claims

1. An electrical power generator comprising: a stator having a surface; a rotor arm having an end located adjacent to the surface ; a rotor axis around which the arm is arranged to rotate; the arm being arranged for the end to move away from the axis during increasing arm rotation and move towards the axis on decreasing arm rotation.

2. An electrical power generator defined by claim 1 wherein the surface is a curved surface.

3. An electrical power generator defined by either claim 1 or 2 wherein the arm is arranged for the end to swing away from the axis during increasing arm rotation and swing towards the axis on decreasing arm rotation

4. An electrical power generator defined by any one of the preceding claims wherein the end of the rotor arm comprises one or more magnets.

5. An electrical power generator defined by any of the previous claims wherein the stator comprises an armature .

6. An electrical power generator defined by any one of the previous claims wherein the stator comprises one or more electrical conductors running adjacent the curved surface and perpendicular to the rotor arm.

7. An electrical power generator defined by claim 6 wherein each of the one or more electrical conductors is traced out by the end when the arm is swung away from the axis but the arm is not rotating.

8. An electrical power generator defined by either claim 6 or 7 wherein each of the electrical conductors is separated from the surface by a magnet .

9. An electrical power generator defined by any one of the preceding claims wherein the surface is an inside hemispherical surface internal of the stator.

10. An electrical power generator defined by any one of the preceding claims wherein the arm is connected to a rotary shaft .

11. An electrical power generator defined by claim 9 wherein the hemispherical surface is capped by a capping member .

12. An electrical power generator defined by claim 9 wherein the hemispherical surface is capped by a capping member, the arm is connected to a rotary shaft, and the rotary shaft passes through an aperture formed in the capping member.

13. An electrical power generator defined by claim 12 wherein the shaft is supported by one or more rotary and/or thrust bearings coupled to the capping member.

14. A wind generator comprising: an electrical power generator defined by any one of claims 1 to 13; and a wind turbine coupled to the electrical power generator to drive it.

15. A device for generating electrical power, the device comprising: an electrical power generator; and a turbine coupled to the electrical power generator to drive it and arranged to capture the kinetic energy of air from an air exhaust.

16. A device as defined by claim 15 wherein the electrical power generator is defined by any one of claims 1 to 13.

17. A device as defined by either claims 15 or 16 wherein the air exhaust is a structure air exhaust.

18. A method of creating a financial instrument tradable under an Emissions Trading Scheme (ETS) , the method comprising the step of exploiting an electrical power generator defined by any one of claims 1-13.

19. A method of creating a financial instrument tradable under an Emissions Trading Scheme (ETS) , the method comprising the step of exploiting a wind generator defined by claim 14.

20. A method of creating a financial instrument tradable under an Emissions Trading Scheme (ETS) , the method comprising the step of exploiting a device for generating electrical power defined by claim 15.

21. A method of generating a feed- in tariff, the method comprising the step of exploiting an electrical power generator defined by any one of claims 1-13.

22. An electrical power generator substantially as herein described with reference to the accompanying figures.

23. A wind generator substantially as herein described with reference to the accompanying figures.

24. A device for generating electrical power substantially as herein described with reference to the accompanying figures .