WO1979000527A1

WO1979000527A1 - Wind-driven electric generator

Info

Publication number: WO1979000527A1
Application number: PCT/SE1979/000012
Authority: WO
Inventors: N Branderud; S Linnman
Original assignee: N Branderud; S Linnman
Priority date: 1978-01-18
Filing date: 1979-01-17
Publication date: 1979-08-09
Also published as: SE7800609L; SE409932B

Abstract

A wind-driven electric generator according to the invention comprises at least two electrodes (A+, G) which generate an electrostatic field between them. One of the electrodes (A+) is formed as a particle generator for generating electrically charged particles which are conveyed by the wind through the electrostatic field. Thereby a potential difference is created between the electrodes, which potential is used to drive a through a load across the electrodes. In previously known constructions of this kind the electrodes are arranged substantially perpendicularly to the wind direction and usually to the ground surface as well. The whole of the electrode surface is then subject to maximum wind load. The wind generator according to the invention is formed in such a way that the electrode surface which is exposed to the wind is extremely small due to the fact that the second electrode (G) extends in a plane substantially parallel to the wind direction. Usually it is then also parallel to the ground and according to one embodiment the second electrode (G) is formed by the ground. The generator according to the invention can be provided with one or more spreader electrodes (A-) which together with the particle generator generate a dispersion field in which the particles, suitably in the form of finely divided water droplets (D+) are given a direction forming an angle to the wind direction so that the droplets are spread over a large wind cross section.

Description

Wind-driven electric generator

The present invention relates to a wind-driven electric generator, comprising at least two electrodes arranged to generate between them an electrostatic field, one electrode being formed as a particle generator for generating electrically charged particles, intended to be conveyed by the wind through the electrostatic field, a potential difference thus being created between the two electrodes, and utilized for driving a current through a load across the electrodes.

It is previously known to obtain electrical energy by allowing a gas to convey electrically charged particles from a particle generator against the action of an electrical field to a collector electrode, e.g. according to US-PS 3 191 077 and 3 417 267. Attempts have also been made in the US with electric generators of this kind, and they a re described in a report with the title "Electro fluid dynamic wind driven generators" from the Research Institute, University of Oayton, Ohio, published in October 1976.

Both these US patents relate to energy converters for rapidly flowing gases with relatively high pressure, e.g. steam, where electrica l ly cha rged pa r t ic les a re caus ed to f low at h igh s peed aga ins t the action of an electric field, the kinetic energy of the particles being directly converted to electrical energy without the intermediary of moving parts. Neither of these patents a re , however, intended for use in conjunction with a wind-driven electric generator. The report from the Research Institute, University of Dayton, describes a wind-driven generator where the electrostatic field is generated between two electrodes, each consisiting of a network of tubes or rods and arranged substantially perpendicular to the wind direction and usually to the ground surface as well. The whole of the electrode surface will thus be subjected to maximum wind load. The charged particles, consisting of water droplets, are spread over the wind cross section with the help of hoses and several nozzles. A disadvantage with this known structure is naturally that the costs of the electrodes will be high, inter alia since the surfaces the electrodes expose to the wind will be large, which requires very stable structures to resist the wind load.

The object of the present invention is to achieve a wind driven electric generator not having the disadvantages of the known generator described above, and where the electrode surface exposed to the wind is extremely small compared with corresponding surfaces in the known generator. This object is essentially achieved in that the second electrode extends in a plane substantially parallel to the wind direction.

By making the electrodes in the form of a network or concen t r ic rings, for example, substantially parallel to the wind direction, and thereby also to the ground plane, the exposed electrode surface in the wind direction will be minimum, so that the generator can be dimensioned for considerably smaller wind loads than is the case for the known generator. In the case where the second electrode is the ground surface, the cost of this electrode is reduced, which means a considerable saving in installation costs.

In accordance with one embodiment of the invention, one or more spreader electrodes can be utilized together with the particle generator for generating a dispersion field, in which the particles generated by the particle generator are given a direction forming an angle to the wind direction so that the particles a re spread over a large wind cross section. Large wind cross sections can thus be utilized with a minimum surface of any structural members being exposed in the wind direction. With this embodiment the material costs for a generator in accordance with the invention can be further reduced. Some embodiments, selected as examples, of a generator in accordance with the invention as disclosed in the accompanying claim 1 will now be described in detail, while referring to the accompanying drawings on which

Fig. 1 shows a simple embodiment of a wind generator in accordance with the invention, with a particle generator connected to ground,

Fig. 2 shows another embodiment comprising a spreader electrode arranged above the particle generator,

Fig. 3 shows a further embodiment with two spreader electrodes arranged substantially in the same horizontal plane as the particle generator,

Fig. 4 shows another embodiment with two spreader electrodes arranged concentrically about the particle generator,

Fig. 5 shows the apparatus in Fig. 4 seen from above,

Fig. 6 shows the flux lines in an embodiment where the spreader electrode consists of a ring arranged concentrically about the particle generator,

Fig. 7 shows an embodiment where the spreader electrode is arranged under the particle generator. In the embodiment shown in Fig. 1, a first electrode A+ generates electrically charged water droolets D+ according to some generally known method. In this case, the droplets are oositively charged and denoted by D+ in the Figure. The particle generator A+ is arranged at a certain height above a second electrode G and connected to this electrode via a load resistance R. The second electrode G is extended in a plane substantially parallel to the wind direction. The water droplets D+ generated by the particle generator A+ a re entrained by the wind and conveyed away from the apparatus. The electrode G suitably consists of a ground surface (earth) and can be a land or water surface.

Positive charges a re thus conveyed away from the particle generator which thus has a lack of such and will consequently be negatively charged. A potential difference, or electrical field, is created in this way between the particle generator A+ and the second electrode G. This field strives to convey the positively charged water droplets D+ to the negatively charged particle generator. However, the wind conveys the droplets in the opposite direction, and since it performs work in the electrical field, it is thus retarded. if the potential of the system is allowed to increase unlimitedly, the electrical forces striving to keep the water droplets at the particle generator will become so strong that the wind will no longer be capable of conveying further droplets away.

According to the invention, the particle generator is discharged via a load resistance R, causing current to flow from the electrode G through the load R to the particle generator. When the particle generator is discharged via the load R, the potential of the particle generator is prevented from being so strongly negative that conveyance of charged particles away from it ceases. The wind thus continuously conveys positive charges D+ away from the particle generator. The current flowing from the particle generator is equivalent to an equally large current flowing to the system via the load. The load R is thus supplied with electrical energy which can be utilized in a conventional manner.

Fig. 2 shows another embodiment of an apparatus in accordance with the invention. In this case the particle generator is connected to the positive pole of a voltage source E. The negative pole E of the source is connected to an electrode A-. The wind passes between the particle generator A+ and the electrode A-. The positively charged water droplets D+ generated by the particle generator A+ in Fig. 2 will be attracted by the electrode A-. On their way towards the electrode A-, the droplets will, however, be entrained by the- wind. The apparatus in Fig. 2 otherwise functions as the apparatus in Fig. 1. The advantage with an apparatus as in Fig. 2 is that the water droplets D+ are spread over a larger area with the aid of the electrical field between the particle generator A+ and the electrode A-. The apparatus in Fig. 2 thus exposes a larger surface to the wind, and greater power can thus be produced. The voltage across E can be adjusted so that no, or only a small number of droplets reach the A-electrode, resulting in that no, or very small current flows through the voltage source E. This means that no, or insignificant power is taken from the voltage source E.

Fig. 3 shows a third embodiment of an apparatus in accordance with the invention. The electrode A- and the oarticle generator A+ have been placed here in substantially the same horizontal plane. A second spreader electrode Al is situated between the spreader electrode A- and the particle generator A+. The electrode Al has a positive potential in relation to the particle generator A+. This potential difference is provided by the voltage source E1. The voltage across the voltage source E1 is not high enough to prevent the drodets D+ from the particle generator A+ from still moving towards the electrode A- .

The positive electrode A1 repels the positively charged droplets D+ on their way towards the electrode A- and the particle generator A+ The droplets will therefore travel in a curve up from the oarticle generator A+. The wind simultaneously entrains the drops, and conveys them away from the particle generator. The working principles a re otherwise the same as previously. No current flows through the voltage source E1, and the power output is therefore zero in this case.

In accordance with the invention, the ground under the apparatus can form the electrode A1, since the ground will maintain a positive potential in relation to the particle generator A+. The great advantage with an apparatus as in Fig. 3 is in that it can be built up at a relatively low height above ground but still utilize the winds at greater height. The apparatus can be built practically as large as is desired, using present conventional building technology. The material and building costs will be low in relation to the power which can be developed.

If the spreader electrodes A1 and A- are formed as concentric rings around the particle generator A+ (see Fig. h) , an apparatus is obtained which functions as the apparatus in Fig. 3, but which is independent of the wind direction.

Only a few examples have been demonstrated here of how the apparatus according to the invention can be formed. The possibility of variation is naturally great. For example, the spreader electrodes A- and A1 can be formed as flat networks of electrically conductive material. The electrodes can also be separated into several part electrodes.

Fig. 6 is a vertical section through an embodiment of the invention in which an annular spreader electrode A- is arranged concentric in relation to the centrally placed particle generator A+ and the fields formed round the generator, as well as the paths of the particles D+ in these fields also being shown.

Fig. 7 shows a further embodiment where the spreader electrode A- is arranged under the particle generator, and where the droplets D+ on their way towards the spreader electrode a re entrained by the wind and carried away.

Neither is the application of the inventive principles limited to utilization of positively charged water droplets. The principles a re naturally also applicable to negatively charged particles.

The charged particles can be water droplets or any other type of charges particle at all.

The charged particles which are conveyed away by the wfnd can possibly constitute an environmental hazard. To avoid this, the effect of the transmitted particles can be neutralized, in accordance with the invention, by charged particles of opposite polarity being emitted from an apparatus in the vicinity of the first one. Power stations utilizing the inventive principles are thus suitably built in pairs, one of them emitting positive particles and the other negative particles.

Production of the water droplets is carried out with known techniques which are, inter alia, described in the article with the title "Production of monodisperse liquid particles by electrical atomization" of Vonnegut et al, in the Journal of Colloid Science No. 7,

Claims

1. A wind-driven electric generator, comprising at least two electrodes which are generating an electrostatic field between them, one being formed as a particle generator for ge-nerating electrically charged particles, intended for conveyance by the wind through the electrostatic field with such direction that they are retarded by the field, a potential difference thus occurring between the two electrodes which is utilized for driving a current through a load connected between the electrodes, characterized in that the second electrode extends in a plane substantially parallel to the wind direction.

2. Generator as claimed in claim 1, characterized in that the second electrode consists of a ground surface which can be either land or water.

3. Generator as claimed in any of the preceding claims, characterized in that one or more spreader electrodes a re arranged to generate a dispersion fjeld together with the particle generator, at least a portion of the particles generated by the particle generator being given a direction in said field such as forms an angle to the wind direction so that the particles are spread over the wind cross section.

4. Generator as claimed in claim 3, characterized in that at least one spreader electrode has a polarity opposed to that of the particles generated by the particle generator, and is arranged to form a dispersion field which is substantially perpendicular to the wind direction.

5. Generator as claimed in claim 3, characterized in that at leas a first spreader electrode has a polarity opposite to that of the particles generated by the oarticle generator and which is at substantially the same level above the second electrode as the particle generator, and in that at least one second spreader electrode has the same polarity as the particles generated by the particle generator and is between the first spreader electrodes and the particles generator.

6. Generator as claimed in claims 1, 2 and 5, characterized in that the second electrode simultaneously serves as a spreader electrode.

7. Generator as claimed in claim 5 or 6, characterized in that the first and second spreader electrodes are substantially annular in shape and arranged concentrically in relation to the centrally placed particle generator.

8. Generator as claimed in any of the preceding claims, characterized in that two particle generators emit particles of opposing polarity, and are situated adjacent each other so that the charges neutralize each other.

9. Generator as claimed in any of the preceding claims, characterized in that the particles consist of water droplets.