WO2013114136A1

WO2013114136A1 - Wind turbine

Info

Publication number: WO2013114136A1
Application number: PCT/GB2013/050241
Authority: WO
Inventors: Khalil Abu Al Rubb
Original assignee: Smith, Andrew
Priority date: 2012-02-02
Filing date: 2013-02-01
Publication date: 2013-08-08
Also published as: GB201201876D0; GB2499010A

Abstract

The invention is a stationary airborne wind turbine mounted on a balloon. The balloon is elongate and the blades (8.31, 8.32) of the turbine are mounted to revolve about the device. The balloon is anchored to the ground and controllable from the ground. The balloon is for use at high altitudes within a jet stream.

Description

Wind Turbine

This invention relates to airborne wind turbines and specifically to wind turbines mounted on balloons.

Wind is a freely available source of kinetic energy that can be transformed into electrical energy by turbines. As wind speed increases, the kinetic energy of the wind increases. The power available from a wind increases as the cube of velocity. For example, tripling a wind velocity provides 27 (3³) times the available power. Wind speed can double with every 100 meter increase in altitude from ground level.

A turbine is a rotary engine that extracts energy from a fluid flow. Turbines can be used to produce electrical energy from wind energy. A turbine may be supported in the air without a tower and such a device is termed an airborne wind turbine. Both high and low altitudes are suitable for airborne wind turbines as air currents occur at both altitudes. Airborne wind turbines operating at each altitude have different associated considerations. Lower altitudes have lower wind velocities and the turbine can more easily brought to ground level, but the wind direction and speed may be erratic. Winds at higher altitudes become steadier, more persistent and of higher velocity. With steadier and more predictable winds, high-altitude wind has an advantage over wind near the ground. Further, high-altitude wind generators can be adjusted in height and position to maximize energy return, which is impractical with fixed tower-mounted wind generators. Very high velocity winds are associated with fast flowing, narrow winds called jet streams. The strongest jet streams are those found in the polar regions of the planet between seven and twelve kilometres above sea level. Subtropical jet streams can be found at an altitude between ten and sixteen kilometres above sea level.

Within a given area below any jet stream altitude, but around or above two kilometres from a ground surface, there are strong winds and a large number of wind powered airborne generators may be provided at different altitudes within the given area. This arrangement for providing a plurality of generators allows an increased power density per ground area unit compared to an arrangement whereby all generators are provided at a substantially identical altitude.

After an airborne turbine has harvested mechanical energy from the wind's kinetic energy, the electrical energy must be transferred to the ground. The electrical energy may be converted to laser light or microwave radiation for power beaming to a receiver, or transmitted via a conducting cable.

An aspect of the invention is a wind powered electricity generating device comprising an elongate balloon arrangement filled with a lighter-than-air gas, a turbine to produce electricity from rotational movement, a sail array operable to rotate about the device, and a restraining means coupled to the balloon arrangement. The movement of the balloon arrangement is restricted by the restraining means and a rotation of the sail array provides a force to drive the turbine. The balloon is negatively buoyant compared to the surrounding atmosphere and is held aloft in position by the restraining means. Wind flows along the elongate balloon arrangement and across the sail array. The sail array rotates and provides a rotational movement to the turbine, which uses the movement to produce electricity.

Preferably, the sail array operable to rotate around a longitudinal axis of the balloon arrangement. This provides for a streamlined body for the device with a sail array capturing wind passing over the device. The body of the balloon will act to increase the wind velocity as it passes over the device providing greater power for the sail array to capture compared to the surrounding wind unaffected by the device.

Preferably, the sail array is operable to rotate around a central portion of the balloon arrangement. This provides a stability of the device as the centre of mass and the centre of drag are located close to each other. To move the centre of drag along the elongate balloon in the direction of the wind, control surfaces, such as fins, may be placed towards an end of the balloon arrangement away distal to the oncoming wind. Preferably, the sail array comprises a circular rim and a plurality of sails projecting outwardly from the rim. The sails project orthogonally to the longitudinal axis of the balloon arrangement. The outwardly projecting sails capture the energy of the wind and the circular path that they take, held by the circular rim, provides for smooth rotation of the sail array.

Preferably, the sail array is a first sail array and the device further comprises a second sail array, the first and second sail arrays are operable to rotate around the longitudinal axis of the balloon arrangement, and the second sail array is spaced along the longitudinal axis from the first sail array. A second sail array provides additional rotational power, harvested from the wind, for electricity generation. Preferably, the device further comprises a plurality of sail arrays, wherein the further sail arrays are spaced along the longitudinal axis from each other, the first sail array and the second sail array. The greater the number of sail arrays, thus sails, that are supported by the device, the greater the electricity generation will be.

Preferably, the first sail array is operable to rotate in a first direction, the second sail array is operable to rotate in a second direction, and the first direction is opposite to the second direction. A sail array rotating around the body of the balloon arrangement will cause a torsion force acting in a direction opposite to the rotation of sail arrangement. This torsion force will act to rotate the balloon arrangement and a counter force must be provided to stop the balloon from rotating. This counter force may be provided by the restraining means, and/or by a sail rotating in an opposite direction to the first, thus providing an opposite rotational force acting on the balloon arrangement.

Preferably, half of the sail arrays are operable to rotate in one direction and the other half of the sail arrays are operable to rotate in another direction opposite to the first direction. Equal numbers of arrays rotating in opposite directions provide a near cancelling of the torsion force acting on the balloon arrangement. The balloon arrangement may comprises a single balloon. A single balloon provides a simple design with a large amount of lift provided by the balloon in view of its size.

The balloon arrangement may comprises a first balloon and a second balloon. The first balloon and the second balloon being separated by a chamber. This multi-chamber balloon arrangement provides a section of the device for mechanical and electrical purposed. Preferably, the chamber houses the turbine. The device may further comprise an alternator housed within the chamber. Providing components within the balloon arrangement allows for streamlining of the device with least disruption to the airflow around the device, which affects the efficiency of the sails. A reduction in the sails efficiency reduces the electrical power generated by the device.

Preferably, the device further comprises an alternator and the alternator is suspended below the device. A simple design of the device provides components suspended below the device. The suspended components counter any rotation of the balloon arrangement about its longitudinal axis.

Preferably, the retaining means comprises a plurality of cables attached to the balloon arrangement and a ground anchor. Each cable has a first end coupled to the balloon arrangement and a second end coupled to the ground anchor. The plurality of cables provides an arrangement whereby the balloon is held most securely and movement is prevented in most degrees of freedom.

Preferably, the ground anchor is coupled to each cable by a winch. The winch is operable to shorten the length of the cable thereby drawing the device closer to the ground anchor. The orientation and height of the balloon is controlled by the lengths of the cables projecting from the balloon to the anchor. Varying the height allows for the wind at different altitudes to be captured. Preferably, the ground anchor is operable to rotate the respective orientation of the cables thereby changing the orientation of the device. Varying the orientation of the cables allows the direction that the balloon arrangement faces to the altered. The balloon arrangement facing into the wind will provide the most power as the sails will work most efficiently. Also, the balloon arrangement will generate least drag from incident wind, reducing the wear on the device. Preferably, the balloon arrangement is operable to be held by the retaining means at an altitude of between 7 and 16 km above sea level. This altitude corresponds to the jet stream, which provides reliable and fast winds.

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is as perspective view of a first embodiment of the device;

Figure 2 is a side-view of the first embodiment;

Figure 3 is a sectional view along line X-X of Figure 2;

Figure 4 is a sectional view of a first embodiment of the balloon of the device;

Figure 5 is a sectional view of a second embodiment of the balloon of the device;

Figure 6 is a sectional view of a third embodiment of the balloon of the device;

Figure 7 is a sectional view of a fourth embodiment of the balloon of the device;

Figure 8 is a side-view of a second embodiment of the device;

Figure 9 is a sectional view of a third embodiment of the device;

Figure 10 is a sectional view of a fourth embodiment of the device;

Figure 11 is a perspective view of a fifth embodiment of the device;

Figure 12 is a perspective view of an embodiment of an anchor station used with the device; and

Figure 13 is a sectional view of part of the anchor station of Figure 12.

Figure 1 shows a wind powered electricity generating device 1. The device has a balloon 1.1 in a cylindrical form. The cylinder has two flat ends. Between the two ends around a central part of the balloon 1.1 is a sails 1.2 assembly. The sails assembly 1.2 has a plurality of sails 1.3 attached to it. The sails assembly 1.2 is operable to be rotated about the balloon. The balloon 1.1 has a anchoring point 1.4 at one end allowing the device to be anchored to another object. Figure 1 shows the centre line of the elongate cylindrical balloon 1.1. The balloon 1.1 has a lateral axis running along its length, which is coaxial with the centre line shown in the figure. The sails 1.3 extend in a lateral direction, orthogonal to the longitudinal axis of the balloon 1.1. The sails assembly 1.2 rotates the sails 1.3 along a transverse plane of the device, whereby the sails 1.3 extend laterally along the transverse plane, i.e. the transverse plane is orthogonal to the longitudinal axis.

In use, wind passing along the device 1, from one end of the balloon 1.1 to the other, passes over the sails 1.3. A sail is a device operable to provide a surface to act with an associated air current to provide a force. A sail may be a rigid or flexible structure or a combination of the two. The sails convert the wind force into a directional force acting across the balloon (parallel to the ends of the balloon). The force provided by the sails 1.3 acts to rotate the sales assembly 1.2 around the balloon. The balloon is fixed at its anchor point 1.4 and the movement of the device 1 is thereby restricted.

A balloon may have more than one anchoring point as additional anchoring points provide a more secure and stable anchoring for a balloon. One embodiment of the invention provides four anchoring points.

Figure 3 shows the device of Figure 2 in cross-section. The sails 3.3 are distributed around the sails assembly 3.2. The sails assembly is concentric about a centre portion 3.5 of the device. Disposed between the centre portion 3.5 and the sails assembly 3.2 are a plurality of bearings 3.21. Arrows indicate corresponding movement of the sails 3.3 and the sails assembly 3.2 to which they are attached.

Figure 4 shows an embodiment of the balloon 4.1 extending from a first end of the device to a second, and the sails assembly is able to rotate in or around a groove in the balloon 4.1.

Figure 5 shows a first balloon 5.11 and a second balloon 5.12. The first balloon 5.11 provides a first end of the device and the second balloon 5.12 provides a second end of the device. Between the balloons is channel in or around which the sails assembly is able to rotate.

Figure 6 shows an embodiment of a balloon 6.1 whereby the balloon has a single chamber with tapered ends. The ends are tapered to be aerodynamic for air flowing over the balloon along a plane running between the two ends of the balloon 6.1.

Figure 7 shows an embodiment having a first 7.11 and second balloon 7.12, each with a tapered end distal to the other balloon.

Figure 8 shows a wind powered electricity generating balloon device. The device is orientated to face the wind 8.0 whereby a fore section of the device faces into the wind and a rear section of the device faces away from the wind 8.0. The device comprises a first balloon 8.11 at the fore of the device, a second balloon 8.12 at the rear of the device, and a central portion 8.6 positioned between the first and second balloons. A fore control surface 8.7 is situated on the first balloon 8.11. The fore control surface has a pivoting end towards the fore of the device and a movable end towards the rear of the device, whereby the rear end of the fore control surface move as indicated by a multidirectional arrow of Figure 8. The second balloon 8.12 at the rear of the device shows three rear control surfaces 8.8 - two orientated vertically and one horizontally. A fourth rear control surface is not visible. Between each of the first balloon 8.11, the second balloon 8.12 and the central portion 8.6 is a sails assembly. A first sails assembly 8.31 is between the first balloon 8.11 and the central portion 8.6. A second sails assembly 8.32 is between the second balloon 8.12 and the central portion 8.6. Each sails assembly 8.31, 8.32 has a plurality of sails mounted around the a assembly, whereby the sails can rotate about the device.

An alternator 8.9 is coupled to the first and second sails assemblies 8.31, 8.32 by a gearing system. The alternator 8.9 produces electrical energy from the mechanical energy from the movement of the sails assemblies. The alternator is suspended below the central portion 8.6 between the first and second sails assemblies 8.31, 8.32. The alternator 8.9 and any associated gearing system may be suspended below or affixed to the central portion 8.6, or it could form part of the central portion. The first and second sails assemblies 8.31, 8.32 may rotate about the device in the same direction, or in different directions.

An independent auxiliary power source may be used to power a control surface 8.7, 8.8 and/or balloon instrumentation for monitoring or controlling the balloon. The power source may be a battery or another wind turbine that could be coupled to a surface of the alternator 8.9.

Figures 9 and 10 show cross-sections across the mid of the device and a number of locations for an alternator 9.9, 9.91, 10.9. Figure 9 shows the device with two alternator locations displayed by broken lines. A first alternator 9.9 is attached to the underside of the central portion 9.5, while a second alternator 9.91 is contained within the central portion 9.5. Both alternator locations 9.9, 9.91 are below the centre of the central portion, thus offsetting the centre of gravity if the device and increasing the stability of the device.

In the embodiment of Figure 10, the alternator 10.9 is suspended below the central portion 10.5 by a plurality of suspension cables 10.11. The suspension cables 10.11 may be replaced by structural supports to suspend the alternator 10.9 below the central portion 10.5.

Figure 11 shows an embodiment of the device with four sail assemblies 11.11, 11.12, 11.13, 11.14 rotatably positioned around a balloon. The airflow direction 11.0 is incident to a fore portion of the balloon and a rear potion of the balloon has a plurality of control surfaces 11.8 attached. A first and third sail assembly 11.11, 11.13 are operable to rotate in a first direction (see arrow on Figure 11) and a second and fourth sail assembly 11.12, 11.14 are operable to rotate in a second direction (see arrow on Figure 11), opposite to the first direction. Each sail assembly comprises a plurality of sails, preferably an equal number of sails, coupled to each sail assembly and attached in a manner to cause rotation of the corresponding sail assembly in either the first or the second direction when subject to incident airflow 11.0.

The balloon may be formed of a single balloon, a single structure with multiple inflatable chambers, or from multiple balloons separated by non-inflatable chambers.

Figure 12 shows an anchor station to be used with an above described device to anchor the device. The anchor station comprises an anchor base formed of a rotatable ellipse, or preferably a circular, base 12.1. The anchor base 12.1 is rotatable by rotating means formed by a motor 12.3 and gear 12.4 system. Four winches 12.5 are attached to the anchor base 12.1 spaced around the base 12.1. Each winch 12.5 is coupled to a anchor cable 12.2, and is operable to lengthen or shorten the length of a cable 12.2 projecting from the winch 12.5. In use, the cables 12.2 are coupled to the anchor base 12.1, by a winch 12.5, and also to an airborne wind turbine balloon device. The cables are anchored to the device around the structure of the device so that the orientation of the device is fixed by the orientation of the anchor cables 12.2, which is controlled by the anchor base 12.1 and the associated rotating means. By rotating the horizontal orientation of the cables, the horizontal orientation of an airborne balloon device attached to the cables is changed. This enabled the ground anchor to steer the balloon into a wind to maximise the power which can be generated by an onboard turbine. The pitch and roll of the balloon can also be controlled by setting opposite anchor cables to have differing lengths. The balloon can be winched back to ground level when required in a controlled manner by the anchor device.

A cable 12.2 is ideally composed of a light and strong material, not necessarily a metal, and may be a single strand or a plurality of strands woven together. The cable 12.2 can have a purely tensional role, or may also carry an electric current either within the cable itself, if an electrical conductor is used for the cable, or within a separate conductor attached to the cable 12.2. Figure 13 show a vertical cross-sectional view along the line A-A of Figure 12. The motor 12.3 and gear 12.4 of Figure 12 correspond to a motor 13.3 and gear 13.4 of Figure 13, respectively. In Figure 13, the motor 13.3 is shown as resting on an upper surface of a section of ground 13.9 (lightly shaded). The anchor base 12.1 of Figure 12 corresponds to an anchor base upper 13.11 and an anchor base lower 13.12 ofFigure 13. The anchor base lower 13.12 rests on the a surface of the ground 13.9 and is attached to the ground 13.9 by a foundation 13.6 (block coloured) within the ground 13.9.

The anchor base upper 13.11 and lower 13.12 are rotatably coupled, wherein the upper can rotate horizontally (into and out of the surface of Figure 13) with respect to the lower. The anchor base upper 13.11 and lower 13.12 are curved in a horizontal plane and are operable to rotate about the motor 13.3 and gear 13.4 in the horizontal plane. A bearing 13.7 (dark shaded) is disposed between the anchor base upper 13.11 and lower 13.12 to reduce any frictional force between the two during rotation. The gear 13.4 is operable to transmit a force provided by the motor 13.3 to the anchor base upper 13.1 1 for causing rotation of the upper 13.11 relative to the anchor base lower 13.12.

Claims

1. A wind powered electricity generating device comprising

an elongate balloon arrangement filled with a lighter-than-air gas;

a turbine to produce electricity from rotational movement;

a sail array operable to rotate; and

a restraining means coupled to the balloon arrangement; wherein

movement of the balloon arrangement is restricted by the restraining means; and

a rotation of the sail array provides a force to drive the turbine.

2. A wind powered electricity generating device according to claim 1, wherein the sail array is operable to rotate about the device and preferably around a longitudinal axis of the balloon arrangement.

3. A wind powered electricity generating device according to claim 1 or claim 2, wherein the sail array is operable to rotate around a central portion of the balloon arrangement.

4. A wind powered electricity generating device according to any preceding claim, wherein the sail array comprises

a circular rim; and

a plurality of sails projecting outwardly from the rim; wherein

the sails project orthogonally to the longitudinal axis of the balloon arrangement.

5. A wind powered electricity generating device according to any preceding claim, wherein the sail array is a first sail array and the device further comprises a second sail array;

the first and second sail arrays are operable to rotate around the longitudinal axis of the balloon arrangement; and

the second sail array is spaced along the longitudinal axis from the first sail array.

6. A wind powered electricity generating device according to claim 5, further comprising a plurality of sail arrays; wherein

the further sail arrays are spaced along the longitudinal axis from each other, the first sail array and the second sail array.

7. A wind powered electricity generating device according to claim 4 or claim 5, wherein the first sail array is operable to rotate in a first direction;

the second sail array is operable to rotate in a second direction; and

the first direction is opposite to the second direction.

8. A wind powered electricity generating device according to any of claims 5 to 7, wherein

half of the sail arrays are operable to rotate in one direction; and

the other half of the sail arrays are operable to rotate in another direction opposite to the first direction.

9. A wind powered electricity generating device according to any preceding claim, wherein the balloon arrangement comprises a single balloon.

10. A wind powered electricity generating device according to any of claims 1 to 8, wherein

the balloon arrangement comprises a first balloon and a second balloon; and

the first balloon and the second balloon are separated by a chamber.

11. A wind powered electricity generating device according to claim 10, wherein the chamber houses the turbine.

12. A wind powered electricity generating device according to claim 10 or claim 11, wherein the device further comprises an alternator and the alternator is housed within the chamber.

13. A wind powered electricity generating device according to any of claims 1 to 11, wherein the device further comprises an alternator and the alternator is suspended below the device.

14. A wind powered electricity generating device according to any preceding claim, the retaining means comprising

a plurality of cables attached to the balloon arrangement; and

a ground anchor, wherein

each cable has a first end coupled to the balloon arrangement and a second end coupled to the ground anchor.

15. A wind powered electricity generating device according to claim 14, wherein the ground anchor is coupled to each cable by a winch operable to shorten the length of the cable thereby drawing the device closer to the ground anchor.

16. A wind powered electricity generating device according to claim 14 or claim 15, wherein the ground anchor is operable to rotate the respective orientation of the cables thereby changing the orientation of the device.

17. A wind powered electricity generating device according to any preceding claim, wherein the balloon arrangement is operable to be held by the retaining means at an altitude of between 8 and 17 km above sea level.