AERIAL WIND POWER GENERATION SYSTEM AND METHOD
An aerial power generation system includes a guide line supported by a support body. Wind driven elements are configured and shaped to provide maximum force from both lift and drag during the downwind phase of operation and minimum force during the upwind phase. The guide lines add stability to the system and provide better control over angular orientation and direction of motion. Power transfer is through one or more tow lines connected from the driven elements to power generation devices on the ground. Another embodiment of the aerial power generation system includes a revolving apparatus and two or more wind powered driven elements connected by tow lines to the revolving apparatus. The method includes changing the driven elements between high and low force configurations for downwind and upwind operation, and flying the driven elements in a selected pattern perpendicular to the tow line.
This application is a divisional of Ser. No. 11/307,890 filed Feb. 27, 2006, which is a continuation-in-part of Ser. No. 11/164,512 filed Nov. 28, 2005.
TECHNICAL FIELDThe present invention relates to power generation and more particularly to systems and methods that convert wind energy acting on aerial wind driven elements to rotary or electrical power.
BACKGROUND ARTAs fossil fuels become depleted and more expensive, the need for cost competitive methods and apparatus for harnessing renewable energy sources increases. The wind was long used for powering sailing ships and windmills, but the advent of steam engines or turbines, internal combustion engines, and gas turbines provided cheaper, more convenient energy sources. Less expensive and more efficient apparatus and methods for utilizing wind power would now be beneficial.
Windmills (or wind turbines) are currently being used to generate electricity and to drive pumps, however the cost to generate electricity with a windmill is still more expensive than the cost of electricity generated from fossil fuels. Windmills have a high capital cost relative to power generated. Wind speed, in general, is higher and more consistent with increasing altitude. There is potential to generate significant power with airborne or aerial apparatus at altitudes above the heights reasonably reachable by ground-based windmills.
The challenge with wind power generation is to convert the linear power of the wind to rotary motion to drive an electrical generator or a pump. One known approach to aerial wind power generation is a tethered, aerial windmill. Such aerial windmills can be supported by lighter than air aircraft, such as a blimp, or by lift from airfoil wing structures. These aerial windmills are relatively heavy and require long, heavy electrical cables to transmit the generated power to ground level.
A second known approach to aerial wind power generation is a wind powered element, such as a kite, blimp or airfoil, that is connected to a tow line. The tow line wraps around a reel on the shaft of a ground level power generation device. As the wind powered element is pulled by the wind, the distance from the wind powered element to the shaft increases and the tow line rotates the reel and shaft to generate power. The angle of attack or the shape of the wind powered element is changeable so that the wind powered element can be reeled back towards the ground level power generation device with little power use.
A third known approach to aerial wind power generation is an endless chain of spaced kites linked to the shaft of a ground level power generation device. The kites follow an ascending path and a descending path. The kites are adjustable to provide higher lift while on the ascending path.
DISCLOSURE OF THE INVENTIONAn aerial power generation system includes a guide line that extends skywards at a selected angle. The guide line is connected at the upper end to a support body. A wind powered driven element is slidably mounted on the guide line. The driven element uses a sail-like design with curvature about a horizontal axis so as to maximize the lift and drag wind forces, or the driven element includes a rotatable hub with a plurality of airfoil blades. The driven element is connected by a tow line to a reel on a shaft of a means for generating power. Means are provided for changing the driven element from high force configurations to low force configurations.
Another aerial power generation system includes a plurality of wind powered driven elements connected by tow lines to spaced attachment points on a revolving apparatus that drives a means for generating power. A means for changing the driven elements between high force configurations and low force configurations changes each driven element to high force configurations when the respective attachment point is moving downwind and to low force configurations when the respective attachment point is moving upwind to cause rotation of the revolving apparatus. The driven elements are flown in a pattern at a high speed perpendicular to the tow line, when in the high force configurations, to increase the power generated.
Another aerial power generation system includes an airfoil driven element and a means for adjusting the elevation and azimuth angles of the driven element connected through a swivel to a tow line that is connected to a means for generating power. A method of aerial power generation includes flying the driven element at high speed perpendicular to the tow line in a selected pattern, such as a circle.
BRIEF DESCRIPTION OF THE DRAWINGSDetails of this invention are described in connection with the accompanying drawings that bear similar reference numerals in which:
Referring now to
The driven element 16 is slidably attached or mounted on the first guide line 14. The driven element 16 is a kite, sail, airfoil or other element that generates both drag and lift from the wind. The first and second tow lines 17 and 18 each connect at one end to the driven element 16. The first tow line 17, and generally the second tow line 18, connect to the means for generating power 19 to rotate the means for generating power 19 to generate power. The means for generating power 19 is generally positioned near the first end 21 of the first guide line 14, and can be an electrical generator, a rotary pump, a compressor or other rotary power generation equipment.
A pulley block 34 having three pulleys 35 in a triangular arrangement is slidably mounted onto the first guide line 14, with two pulleys 35 above and one pulley 35 below the first guide line 14. A plurality of support lines 37 attach to the pulley block 34, and diverge outwardly and downwardly therefrom to attach in a spaced arrangement along the upper spar 25 of the driven element 16. The first tow line 17 attaches to the upper spar 25 and the second tow line 18 attaches to the lower spar 26. Although a single driven element 16 is shown, a train or string of driven elements 16 can be used.
In
Referring to
The first tow line 17 wraps around the first reel 52 and the second tow line 18 wraps around the second reel 53. The first reel 52 is rigidly attached to the shaft 51 and the second reel 53 is rotatably mounted on the shaft 51. The second reel 53 has cylindrical drum 60 mounted on the shaft 51 by bearings, and spaced first and second flanges 61 and 62 at opposite ends of the drum 60. A toothed gear 64 is rigidly attached to the shaft 51 and spaced from the second flange 62. Two control motors 66 are mounted on the outside of the second flange 62 on opposite sides of the shaft 51. A worm gear 67 is connected to and driven by each control motor 66, with the worm gears 67 being parallel and meshing to opposite sides of the toothed gear 64. Two motors are used to provide good mass balance of the reel assembly and thus allow for higher rotation rates. Slipring assemblies 69 on the end of shaft 51 opposite the motor/generator 50 and inside the drum 60 provide power to the control motors 66. Driving the control motors 66 rotates the second reel 53 relative to the first reel 52, lengthening or shortening the second tow line 18 relative to the first tow line 17, thereby providing a means for changing 45 the driven element 16 between high force and low force configurations. Therefore, the second reel 53, toothed gear 64, worm gears 67 and control motors 66 form a means for shortening and lengthening the second tow line 18 relative to the first tow line 17. Alternatively, the means for generating power 19 could include two independent, vertically stacked motor/generators to provide a means for changing 45 the driven element 16 between high force and low force configurations.
The first guide line 14 provides stability to the driven element 16, allowing the use of driven elements 16 with higher power and less stability than the driven elements 16 that could be used without the first guide line 14. The first guide line 14 also guides the driven element 16 along a path having a selected elevation angle, so that the power of the driven element 16 can be further optimized.
Referring to
A winch 88 is mounted in each lower corner of the framework 80. Wires 91 extend from each winch 88 to a control module 90, suspending the control module 90 below the bottom 82, intermediate the winches 88, and connecting the control module 90 to the two winches 88. The suspended control module 90 acts as a tail for the kite 77, increasing the stability of the kite 77. The control module 90 can include, by way of example, and not as a limitation, a two way radio link to the ground, a rechargeable battery, a wind or solar battery charging device, measurement devices and aircraft warning lighting. The measurement devices can include wind speed, light, altitude, GPS, three dimensional acceleration, temperature, humidity, and orientation sensing and measurement.
The bridle 78 includes two each upper bridle lines 93, lower bridle lines 94 and common bridle lines 95. One end of each upper bridle line 93 connects to an outward corner 86 of a wing 85 of the sail portion 84. One end of each lower bridle line 94 connects to a winch 88. The other ends of the upper and lower bridle lines 93 and 94 on each side of the kite 77 connect together and to one end of a common bridle line 95. The other ends of the common bridle lines 95 connect together and to the second end 22 of the first guide line 14. The lower bridle lines 94 in combination with the winches 88 can vary the angle of attack of the kite 77 relative to the wind, thereby forming a means for varying lift 96 (or drag) of the kite 77. Differential control of the lower bridle line lengths will allow for azimuth angle control with respect to the wind direction. Although first support body 15 is shown, second support body 72 will be substantially identical. Although a single kite 77 is shown, a train of kites 77 can be used to form the first or second support body 15 or 72.
As shown in
Referring to
As shown in
Referring to
The means for changing 106 can be a remote control system as described above or other mechanical means for lengthening and shortening the tow line 105 and control line 119 relative to each other. The means for generating power 108 can be an electrical generator, a liquid pump, a compressor or other power transfer device. The power generation system 103 can be scaled from smaller to larger sizes. For smaller sizes of the power generation system 103, the cross bars 113 of the revolving apparatus 107 can be self supporting. Larger versions of the power generation system 103 could have the revolving apparatus 107 as large as a revolving agricultural irrigation system. The cross bars 113 of a large revolving apparatus 107 can be supported by wheels 124 and linked by cables 125. The wheels 124 can carry and drive a generator 126.
A bridle 155 for the driven element 145 includes two upper bridle lines 156 and two lower bridle lines 157. The upper bridle lines 156 connect at one end to corners 153, and the lower bridle lines 157 connect at one end to opposite ends of the bottom spar 149. A generally spherical control module 158 incorporates four winches 159 with the opposite ends of the upper and lower bridle lines 156 and 157 each connecting to a separate winch 159. The control module 158 connects to the upper end of a tow line 105. The control module 158 is remotely controlled and can change the length of each of the upper and lower bridle lines 156 and 157 independently. The control module 158 and the upper and lower bridle lines 156 and 157 provide a means for changing 106 the driven element 145 between high force and low force configurations, and a means for adjusting 160 the azimuth angle of the driven element 145.
Alternatively, the two lower bridle lines 157 can connect to the tow line 105, and two upper control lines can be provided. The upper control lines each connect from a corner 153 of a wind 152 of the sail portion 151 to the end of the cross bar 143 that is opposite the center 142. The two upper lines are independently controlled so that the elevation and azimuth angles can be independently adjusted. The arrangement, with the lower bridle lines 157 connected to the tow line 105 and the two independently controlled upper control lines, provides another structure for the means for changing 106 the driven element 145 between high force and low force configurations, and another structure for the means for adjusting 160 azimuth angle of the driven element 145.
Referring again to
The first upper bridle lines 172 converge to connect to a first upper control line 175 and the second upper bridle lines 173 converge to connect to a second upper control line 176. The lower bridle lines 174 converge to connect to the tow line 105. The first and second upper control lines 175 and 176, and the tow line 105 connect to the end of the cross bar 143 that is opposite the center 142. The first and second upper control lines 175 and 176 are independently controlled so that the elevation and azimuth angles can be independently adjusted. This arrangement, with the lower bridle lines 174 connected to the tow line 105 and the independently controlled first and second upper control lines 175 and 176, provides another structure for the means for changing 106 the driven element 165 between high force and low force configurations, and another structure for the means for adjusting 160 the azimuth angle of the driven element 165.
The control module 190 includes instrumentation such as listed above and a power supply such as a battery for powering the winches and the instrumentation. The control module 190 includes a wireless link for remote control and can also include sensors that measure the tension on the first and second upper control lines 175 and 176 and the lower control line 189. Ground instrumentation, including cameras can also be used to sense the precise position and orientation of the driven element 165. The swivel 191 can incorporate or include a small electrical generator 192, that is turned by rotation of the driven element 165 relative to the tow line 105, to provide power to the power supply. A stabilizer 193, in the form of a weight, as shown, or a fin, is suspended from the tow line 105 below the swivel 191, as a means for preventing the tow line from twisting when the driven element 165 rotates. Alternatively, two independently controlled lines can connect to the trailing edge 167 with at least one other line connecting to the leading edge 166.
A control line 200 extends from the nose 201 of the fuselage 196. A winch inside the fuselage 196 reels the control line 200 in and out. The interior of the fuselage also contains instrumentation such as set forth above. The bridle lines 199 and the control line 200 converge to connect to a swivel 202 that connects to the tow line 105. An attachment point 203 on the fuselage 196 above the wings 197 facilitates stacking of the driven elements 195. The control surfaces 198 and control line 200 provide means for adjusting the azimuth and elevation angles of the driven element 195. The control line 200 is a means for changing the driven element 195 between high force and low force configurations, and is reeled in until the fuselage 196 is substantially parallel to the tow line 105, to change the driven element 195 to a low force configuration.
Winches 211 independently control the lengths of the first and second upper control lines 175 and 176, and thereby form a means for independently adjusting the elevation and azimuth angles of the driven element 165. Through adjustment of the elevation and azimuth angles, the direction of the lift of the driven element 165 is adjusted. If the lift perpendicular to the tow line 105 is greater than the drag perpendicular to the tow line 105, the driven element 165 will accelerate perpendicular to the tow line 105. The driven element 165 can be flown at a selected speed perpendicular to the tow line 105, and can be flown in a selected pattern, by constant adjustment of the lengths of the control lines.
The lift of the driven element 165 is proportional to the square of the velocity of the apparent wind flowing perpendicular to the upper spar 168. The velocity of the apparent wind flowing perpendicular to the upper spar 168 will generally increase as the velocity of the driven element 106 perpendicular to the tow line 105 increases. By adjusting the elevation and azimuth angles of the driven element 165 the driven element 165 can be flown in a circle at high speed. The forces are balanced with inwardly directed force providing centripetal acceleration, forwardly directed force balancing with the drag, and the force parallel to the tow line 105 providing the force that pulls on the revolving apparatus 205.
To prevent tangling, when the first and second upper control lines 175 and 176, and the tow line 105, all attach to the turntable 209, the driven element 165 is flown in a pattern of two connected circles, as shown, flying clockwise through one circle and counter-clockwise through the other circle. By flying the driven element 165 through the pattern at high speed, the total lift and the lift parallel to the tow line 105 are increased, increasing the power generated by the aerial wind power generation system 103.
Referring to
The means for generating power 229 includes a generator 233 connected to a capstan 234. A winch 235 is provided behind the capstan 234 for reeling the tow line 228. The tow line 228 is wrapped around the capstan 234 and turns the capstan 234 to turn the generator 233. The arrangement with a separate capstan 234 and winch 235 prevents excess tension on the wraps of tow line 228 on the winch. The driven element 230 is flown at a high velocity perpendicular to the tow line 228 in a generally circular pattern while the tow line 228 pulls out from the means for generating power 229, forming a corkscrew flight path. When the tow line 228 extends to a predetermined distance, the driven element 230 is changed to a low force configuration and reeled back towards the means for generating power 229. By flying the driven element 230 through the pattern at high speed, the total lift and the lift parallel to the tow line 228 are increased, increasing the power generated by the aerial wind power generation system 227.
Referring to
The driven element 241 has a sleeve 245, a hub 246, a plurality of airfoil blades 247, and a pitch control mechanism 248. The sleeve 245 is slidably mounted on the guide line 240 and connected to one end of the tow line 242. The hub 246 is rotatably mounted on the sleeve 245. The blades 247 preferably have a twisted shape as in propeller or wind turbine rotor blades. The blades 247 are circumferentially spaced on the hub 246 and extend radially therefrom in a plane perpendicular to the guide line 240. The pitch control mechanism 248 links to the blades 247, providing a means for adjusting the pitch of the blades 247 and a means for changing the driven element 241 between high force and low force configurations.
The pitch control mechanism 248 can be controlled by a remote control module 249 mounted on the sleeve 245, as shown, and/or by other sensors such as an altimeter or GPS. The blades 247 are adjusted to spin in response to the wind to change the driven element 241 to a high or low force configuration. As the speed of the blades 247 increases, the direction of the lift from the blades 247 rotates towards the direction of the tow line 242, increasing the force in the direction of the tow line 242. The blades 247 are adjusted such that the lift and drag are minimized while the driven element 241 is in the low force configuration.
Referring to
A control module 257 mounts on the middle spar 251, forward of the centerline of the support body 239. The control module 257 includes two winches 258. Each winch 258 has a control line 259 that connects to a side spar 252. The control lines 259 can pull the side spars 252 inwardly to change the shape of the support body 239. Pulling inwards with one control line 259 causes the support body 239 to fly to one side. Pulling inwards or reeling out both control lines 259 changes the lift and drag of the support body 239. The instrumentation in the control module 257 can provide automatic correction and/or the instrumentation can be remotely controlled. The instrumentation in the control module 257 can provide self-stabilization of the support body 239 in response to wind fluctuation.
Other configurations can be used for the support body 239 and the first and second support bodies 15 and 72, described above. By way of example and not as a limitation, the designs of the driven elements that include azimuth and elevation angle adjustment can be used as support bodies, including the driven element 145, shown in
Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made by way of example and that changes in details of structure may be made without departing from the spirit thereof.
Claims
1. An aerial power generation system for generation of power from the wind, comprising:
- a wind powered driven element, having a high force configuration and a low force configuration, said driven element having, when in said high force configuration, an airfoil shape, an elevation angle and an azimuth angle,
- means for adjusting independently said elevation and azimuth angles,
- means, connected to said driven element, for changing said driven element between said high force configuration and said low force configuration,
- a swivel connected to said means for changing,
- a tow line connected to said swivel, and
- means, connected to said tow line opposite said swivel and driven by said tow line, for generating power,
- whereby said means for adjusting adjusts said elevation and azimuth angles to fly said driven element in a generally circular pattern perpendicular to said tow line while said driven element pulls said tow line, when said driven element is in said high force configuration, and said means for adjusting adjusts said first and second upper control lines to change said driven element between said high and low force configurations.
2. The system as set forth in claim 1 including an electrical generator connected to and driven by said swivel.
3. The system as set forth in claim 1 including a stabilizer attached to said tow line near said swivel to prevent said tow line from twisting as said driven element rotates relative to said tow line.
4. An aerial power generation system for generation of power from the wind, comprising:
- a guide line extending skywardly at a selected elevation angle from a first end to a spaced second end,
- a support body attached to said second end of said guide line for supporting said guide line,
- a wind powered driven element slidably mounted on said first guide line, said driven element including a rotatably mounted hub and a plurality of circumferentially spaced airfoil blades that extend radially from said hub,
- a tow line connected to said driven element, and
- means, connected to said tow line opposite said driven element and driven by said tow line, for generating power,
- whereby said hub rotates in response to the wind on said blades and the rotation of said blades generates lift, pushing said driven element away from said means for generating, whereby said driven element slides along said guide line and pulls said tow line, and said first tow line drives said means for generating power.
5. The system as set forth in claim 4 including:
- means for changing said driven element between high force and low force configurations,
- whereby said means for changing changes said driven element to a said high force configuration to generate power, and said means for changing changes said driven element to a said low force configuration for pulling said driven element towards said means for generating power.
6. The system as set forth in claim 5 wherein:
- each said blade has a pitch angle, and
- said means for changing includes a means for adjusting said pitch angle,
- whereby said pitch angle is adjusted to change said driven element between high force and low force configurations.
7. A method of generating power from the wind comprising the steps of:
- providing a guide line tethered at the lower end and supported at a selected elevation angle by a support body, a wind powered driven element slidably mounted on said guide line, a tow line connected to said driven element and a means for generating power connected to said tow line, said driven element having a high force configuration and a low force configuration,
- changing said driven element to said high force configuration,
- then sliding said driven element along said guide line toward said support body in response to the wind, whereby said driven element pulls said tow line and said tow line drives said means for generating power,
- then changing said driven element to said low force configuration, and
- then pulling said driven element toward the lower end of said guide line.
8. The method as set forth in claim 7 wherein said driven element includes a rotatably mounted hub and a plurality of spaced airfoil blades that extend radially from said hub, each said blade having a pitch angle, and
- including the step of rotating said hub during said step of sliding said driven element.
9. The method as set forth in claim 8 wherein said steps of changing said driven element to said high force configuration and changing said driven element to said low force configuration both include a substep of adjusting said pitch angle of each said blade.
10. A method of generating power from the wind comprising the steps of:
- providing a plurality of aerial wind powered driven elements each having high force configurations and low force configurations, and a separate tow line connected to each driven element, said driven elements each having, when in a said high force configuration, an airfoil shape, an elevation angle and an azimuth angle,
- providing a revolving apparatus and means, linked to said revolving apparatus and driven thereby, for generating power, said revolving apparatus being rotatably mounted about a center and having a tow line attachment point, for each driven element, said tow line attachment points each being connected to a said tow line, said tow line attachment points being linked together, spaced from said center and spaced from each other,
- changing each driven element to a high force configuration for a selected portion of the rotation of the respective said tow line attachment point,
- changing each driven element to a low force configuration for the remainder of the rotation of the respective said tow line attachment point, and
- adjusting said elevation angle and said azimuth angle of each driven element to fly said driven element at a high speed in a selected pattern perpendicular to said tow line, when said driven element is in a high force configuration,
- whereby said driven elements, in response to the wind, rotate said revolving apparatus when in said high force configuration.
11. The method as set forth in claim 10 including the step of:
- adjusting said azimuth angle of each said driven element to fly said driven element at a selected angle relative to the wind,
- whereby each said driven element pulls on said revolving apparatus over an arc greater than 180 degrees.
12. The method as set forth in claim 10 including the step of:
- adjusting said elevation angle and said azimuth angle of each said driven element to fly said driven element at a high speed in a selected pattern perpendicular to said tow line, when said driven element is in a high force configuration.
Type: Application
Filed: Jan 9, 2007
Publication Date: May 31, 2007
Inventor: Gaylord Olson (Princeton, NJ)
Application Number: 11/621,342
International Classification: B64C 27/22 (20060101);