WO2011047208A2

WO2011047208A2 - Tower raising or lowering systems and methods using a buoyant aerostat

Info

Publication number: WO2011047208A2
Application number: PCT/US2010/052755
Authority: WO
Inventors: Daniel Nachbar; William D. Hughes
Original assignee: Skyacht Aircraft, Inc.
Priority date: 2009-10-16
Filing date: 2010-10-14
Publication date: 2011-04-21
Also published as: WO2011047208A3

Abstract

Systems and methods for employing a tethered buoyant aerostat to raise and lower a hinged tower between horizontal and vertical orientations in a controlled fashion is described. The system may be applicable to the use of an aerostat that obtains its lift from hot air.

Description

TOWER RAISING OR LOWERING SYSTEMS AND METHODS USING A

BUOYANT AEROSTAT

CROSS-REFERENCE

[0001] This application claims the benefit of U.S. Provisional Application No. 61/252,543, filed October 16, 2009, which application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] This invention relates to the raising and lowering of a tower using a buoyant aerostat.

BACKGROUND OF THE INVENTION

[0003] Positioning towers in an upright position is one of the oldest undertakings in construction. Many methods exist. For example, one common method, particularly for small towers, is shown in Figure 1. The tower 10 starts in a horizontal orientation. A hinge 20 is attached to the base of the tower 10 and to the ground 50. The axis of rotation provided by the hinge is parallel to the ground 50 and perpendicular to the long axis of the tower 10. A top rope 30 is attached to the top of the tower 10.

[0004] The tower is lifted into an upright position by a top winch 40 or similar device which pulls on the top rope 30. The force of the top rope 30 induces a rotational moment in the tower 10 about the hinge 20 at the base of the tower 10. The top winch 40 continues to pull on the top rope 30 until the long axis of the tower 10 is in an upright orientation.

[0005] The configuration depicted in Figure 1 is only practical for relatively small towers.

The angle between the long axis of the tower 10 and the lifting rope 30 is highly acute, particularly when the tower 10 is close to the ground 50. As a result, only a small fraction of the force in the lifting rope 30 translates to a rotational moment about the hinge 20.

[0006] Figure 2 shows an improved version of this process shown in Figure 1. In the improved configuration, the tower 10, hinge 20, top rope 30, and top winch 40 all function in roughly the same manner as depicted in Figure 1. The principle difference is that the lifting rope 30 is routed over a gin pole 60 that is attached to the base of the tower 10 at or near the hinge 20. The long axis of the gin pole 60 is oriented at a roughly perpendicular angle from the long axis of the tower 10 and within the plane of rotation of the tower 10. The gin pole 60 rotates at the same rate and along the same plane of rotation as the tower 10. Thus, at the completion of the lifting process when the long axis of the tower 10 is upright the long axis of the gin pole 60 is horizontal. A gin pole 60 gives much greater mechanical advantage to the force that is carried by the lifting rope 30 particularly at the start of the lifting process when the tower 10 is near the ground 50.

[0007] Tilting hinged towers into an upright position using ropes and gin poles in the fashion depicted in Figures 1 and 2 has been described on many previous occasions including U.S. Patent No. 2,267,705; U.S. Patent No. 6,782,667; U.S. Patent No. 3,715,852; and U.S. Patent No. 6,408,575; which are hereby incorporated by reference in their entirety.

[0008] However, for large towers, the straightforward tilting process is less effective. In particular, there is still significant mechanical inefficiency during the early stages of the lifting process. These inefficiencies lead to significant compressive stress in the tower 10 and gin pole 60 as well as significant sheer stresses in the hinge 20.

[0009] A further improvement is depicted in Figure 3. All of the components in Figures 1 and 2 operate in the same manner. A lifting frame 70 is attached to the ground 50 and located near the midpoint of the long axis of the tower 10. Unlike a gin pole 60, which rotates during the tilting process along the same plane and at the same rate as the tower 10, the lifting frame 70 stays affixed to the ground 50 and does not move during the tilting process.

[0010] A frame sheave 80 is located at the top of the lifting frame 70. A frame rope 90 is attached at one end to the tower 10 near the midpoint of the long axis of the tower 10. The frame rope 90 is routed through the frame sheave 80. The frame rope 90 is attached at the other end to a frame winch 100.

[0011] Using the configuration depicted in Figure 3, the tower is initially lifted when the frame winch 100 pulls on the frame rope 90. Because the frame rope 90 attaches to the tower 10 at a nearly perpendicular angle, nearly all of the force applied by the frame rope 90 is converted into a rotational moment in the tower 10 about the hinge 20. As the tilting process continues the top winch 40 starts to pull on the top rope 30 and later stages of the tilting process are completed as depicted in Figures 1 and 2.

[0012] The use of lifting frames in the fashion depicted in Figure 3 has been described on many previous occasions. See, e.g., U.S. Patent No. 4,590,718 and the document named WindPact Turbine Design Scaling Studies Technical Area 3 : Self-Erecting Tower and Nacelle Feasibility, Global Energy Concepts, March 2001. NREL Report No. SR-500-29493; which are hereby incorporated by reference in their entirety.

[0013] Neither lifting frames nor gin poles has proved effective for lifting large towers. In particular, neither lifting frames nor gin poles has proved effecting in the installation of utility- scale horizontal-axis wind turbines. Large horizontal-axis wind turbines present a greater challenge because the turbine nacelle, hub, and blades located at the top of the tower have a great deal of weight.

[0014] The gin pole and rope method has proven ineffective for raising large wind turbines because of the inherent mechanical disadvantage embodied in this system. Lifting frames have proven ineffective for large wind turbines because the great weight of the components on the top of the tower combined with the lifting force applied at the midpoint of the tower create significant bending moments in the tower structure. Carrying these bending moments by increasing the amount of material in the tower structure has proven to be economically prohibitive. [0015] As a result of these shortcomings, essentially all large horizontal wind turbines are assembled in the field in the upright position from components. The components are lifted into place by convention ground based cranes. These cranes have proven to be very expensive and their large size has created significant site access problems for wind turbine installers. Upright assembly also requires that workers must connect pieces either by welding or tightening bolts while working at great heights. Operation at great high presents inherent risks to the workers.

[0016] Horizontal tower assembly followed by tilting to an upright position eliminates the risk of working at great heights. Thus, a need exists for systems and methods that induce a rotational moment in the tower structure by applying the lifting force in the vertical direction rather than at an angle that is near the horizontal. In this way, the force of gravity is overcome directly without inducing significant compression or bending loads in the tower structure.

[0017] A further need exists for systems and methods where the lifting force could be applied at the top of the tower where the heaviest components are located, for installing large horizontal axis wind turbines, in order to avoid undue bending moments in the tower. Further, the lifting system could use lightweight components that can be readily transported to the lift site.

SUMMARY OF THE INVENTION

[0018] The invention provides systems and methods for tilting a tower from a horizontal orientation to an upright orientation using a buoyant aerostat to provide the lifting force.

Various aspects of the invention described herein may be applied to any of the particular applications set forth below or for any other types of buoyant assemblies. The invention may be applied as a standalone system or method, or as part of integrated lifting systems, such as lifting or suspending heavy objects. The systems may be particularly applicable to the installation of large horizontal-axis wind turbines. It shall be understood that different aspects of the invention can be appreciated individually, collectively, or in combination with each other.

[0019] One aspect of the invention may be directed to a system for raising a tower. The system may comprise a tower with a hinged end. The system may also include a buoyant aerostat attached to the tower at a free end opposite the hinged end, wherein the buoyant aerostat is configured to lift the free end of the tower while the hinged end remains at a substantially fixed location. The system may also have at least one tether connecting the buoyant aerostat to a reference surface.

[0020] Another aspect of the invention may be directed to a method of raising a tower. The method may comprise the step of providing a tower in a substantially horizontal position, wherein the tower has a first end and a second end. The method may also include connecting a buoyant aerostat to the tower at the second end, and lifting the tower at the second end using the buoyant aerostat, so that the first end remains at substantially the same location. The method for raising a tower may also be applied to lowering a tower in a controlled manner.

[0021] The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below.

INCORPORATION BY REFERENCE

[0022] All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

[0024] Figure 1 shows a side view of a prior art tilt tower lifting system.

[0025] Figure 2 shows a side view of a prior art tilt tower lifting system using a gin pole.

[0026] Figure 3 shows a side view of a prior art tilt tower lifting system using a gin pole and lifting frame.

[0027] Figure 4 shows a side view of a tilt tower lifting system using a buoyant aerostat with four tethers with side tethers offset from a hinge axis.

[0028] Figure 5 shows a top view of a tilt tower lifting system using a buoyant aerostat with four tethers with side tethers offset from a hinge axis. (For clarity, the aerostat is not shown.)

[0029] Figure 6 shows a top view of a tilt tower lifting system using a buoyant aerostat with four tethers with side tethers aligned with a hinge axis. (For clarity, the aerostat is not shown.)

[0030] Figure 7 shows a top view of a tilt tower lifting system using a buoyant aerostat with three tethers. (For clarity, the aerostat is not shown.)

[0031] Figure 8 shows a top view of a two-part tilt tower lifting system using a buoyant aerostat. (For clarity, the aerostat is not shown.)

[0032] Figure 9 shows a side view of a two-part tilt tower lifting system using a buoyant aerostat.

DETAILED DESCRIPTION OF THE INVENTION

[0033] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

[0034] Figure 4 and Figure 5 depict an improved system for tilting a tower 10 into an upright orientation. Figure 4 shows a side view of a tilt tower 10 lifting system using a buoyant aerostat 110 with four tethers 140, 160, 180, 200 with side tethers 180, 200 offset from a hinge axis. A hinge 20 may connect the tower 10 to the ground 50. The hinge 20 may be oriented such that the axis of rotation provided by the hinge may be horizontal and

perpendicular to the long axis of the tower 10.

[0035] A tilt tower 10 may be any structure that may have a significant

vertical/longitudinal dimension. In some instances, the vertical/longitudinal dimension may be substantially greater than the other dimensions. A tilt tower may refer to any tower including but not limited to wind towers, communications towers, poles, structural support,

meteorological measurement tower, tower telescope, solar power station, shot tower, survey tower, launch tower, service tower, supply tower, scaffold. Towers may be structures that are taller than they are wide, usually by a significant margin. Towers may be built to take advantage of their height, and can stand alone or as part of a larger structure. The tilt tower may be include man-made components. In some embodiments, the tower may be pre- assembled before being lifted. For example, the tilt tower may be a pre-assembled wind tower. In some embodiments, a top portion of the tower may be heavier than a bottom portion of the tower. For example, a heavy wind turbine may be at the top portion of the tower. The system may advantageously enable towers to be pre-assembled on the ground and then lifted into an upright position, even if the top portion of the tower is heavy. Any other structure may be erected in the disclosed systems and methods.

[0036] In some embodiments, the ground 50 need not be the earth, but may be any other stable surface. For example, the ground may also refer to a structure that is fixed relative to the ground. Any depiction of the ground 50 may refer to any other reference point. The reference point may be fixed with respect to the ground or any other frame of reference.

[0037] The hinge 20 connecting the tower 10 with the ground 50 may prevent the bottom end of the tower from moving laterally or being displaced horizontally with respect to the ground. Similarly, the hinge may prevent the bottom end of the tower from moving vertically with respect to the ground. The hinge may enable the tower to rotate about the hinge axis, while keeping the position of the hinge axis substantially fixed. In some alternate

embodiments, the hinge may be provided on a track or some other mechanical feature that may enable the bottom end of the tower to move laterally and/or vertically with respect to the ground or any other reference point.

[0038] A tower 10 may have a first end and a second end. In some instances, the first end may be the top of the tower when the tower is raised upright and the second may be the bottom of the tower when the tower is raised upright. The second end may be a hinged end, and the first end may be a free end opposite the hinged end.

[0039] After the lifting process is completed the tower 10 may be kept in a fixed orientation, such as a roughly vertical orientation, by means of a locking mechanism in the hinge 20, the addition of stays, the bolting of the bottom of the tower 10 to the ground 50, or any number of other means or combination thereof at which point the aerostat 110 and or the hinge 20 may be removed.

[0040] A buoyant aerostat 110 may be connected to the tower 10 at the tower top 120 and aerostat base 130. An aerostat or any other buoyant body may be used to lift and/or suspend objects. See, e.g., U.S. Patent Publication No. 2009/0152391; U.S. Patent No. 6,555,931; U.S. Patent No. 4,601,444; U.S. Patent No. 4,071,124; which are hereby incorporated by reference in their entirety.

[0041] In some embodiments, the buoyant aerostat 110 may be attached to the tower 10 at a free end 120 opposite the hinged end. The buoyant aerostat 110 may be configured to lift the free end 120 of the tower 10 while the hinged end remains at a substantially fixed location. In some instances, the free end 120 of the tower may be a heavy end of the tower 10. The buoyant aerostat 110 may advantageously be utilized to lift a heavy end of a tower 10 so that the tower is in a substantially vertical position.

[0042] An aerostat 110 may have any shape. For example, the aerostat may have a roughly ovoid shape. The aerostat may have any shape, which may include a roughly spherical shape, an elongated shape, or any other shape. The aerostat may comprise an envelope. In some instances, the envelope may be a membrane made of flexible fabric material. The envelope may be formed of any material which may include a cloth, fabric, weave, or any other thin, flexible material. The envelope may be roughly axisymmetric about its central vertical axis. Alternatively, it need not be axisymmetric about a vertical axis.

[0043] In order to create a buoyant lifting force, the aerostat 110 envelope may typically be filled with a gas with a density less than the density of the gas found in the surrounding atmosphere. The gas in the envelope cavity may be air that is heated above the temperature of the surrounding atmosphere. Alternatively, in some embodiments, unheated gas, such as hydrogen, helium, or any other low density gas may be provided within the envelope cavity. Any discussion of gas or air may apply to any type of gas.

[0044] The aerostat base 130 may connect to the tower top 120 in any fashion. The connection may enable the aerostat base to be freely rotatable with respect to the tower 10. Thus, an aerostat 110 may retain an upright orientation even while the tower 10 is being rotated into an upright position. In some instances, the aerostat 110 may be connected to the tower 10 so that it is removable.

[0045] Figure 5 shows a top view of a tilt tower 10 lifting system using a buoyant aerostat 110 with four tethers 140, 160, 180, 200 with side tethers 180, 200 offset from a hinge axis. (For clarity, the aerostat is not shown.) A flexible rope called the front tether 140 may attach at one end to the aerostat 110 at the aerostat base 130. The other end of the front tether 140 may connect to the front winch 150. A flexible rope called the rear tether 160 may connect at one end to the aerostat 110 at the aerostat base 130. The other end of the rear tether 160 may attach to the rear winch 170. A flexible rope called the left tether 180 may attach at one end to the aerostat 110 at the aerostat base 130. The other end of the left tether 180 may attach to the left winch 190. A flexible rope called the right tether 200 may attach at one end to the aerostat 110 at the aerostat base 130. The other end of the right tether 200 may attach to the right winch 210.

[0046] A tether (e.g., 140, 160, 180, 200) may be formed of any line or rope of any material. Preferably, the tether may be flexible, while not stretching substantially along the length of the tether. Any number of tethers may be provided. For example, about one, two, three, four, five, six, seven, eight, ten, fifteen, twenty or fifty tethers may be used. The tethers may be spaced in any manner. For example, the tethers may be relatively evenly spaced (e.g., at about 120 degrees if three tethers are provided, at 90 degrees if four tethers are provided, at 360/N if N tethers are provided). The tethers may be arranged so that any number of tethers are on either side of the axis of rotation about the hinge, or on the axis of rotation about the hinge. Aspects of any of the arrangements discussed herein may also apply to various other arrangements.

[0047] A tower raising system may have at least one tether connecting the buoyant aerostat to a reference surface, such as the ground. [0048] A tether (e.g., 140, 160, 180, 200) may preferably be attached to a fixed point on the ground 50. The tether may be connected to any mechanism that may keep the tether connected to the ground. This may include mechanisms such as loops, hooks, clips, weights, anchors, ties, and so forth. In some embodiments, a tether may be connected using a winching mechanism (e.g., 150, 170, 190, 210) that may enable the length of a tether to increase and/or decrease as the winch turns. Other mechanisms may be provided that may allow the length of the tether to increase and/or decrease (e.g., as the tether is extended or retracted). In other embodiments, a winching mechanism, or other mechanism may be mounted on the aerostat that may enable the length of a tether to increase and/or decrease. Alternatively, winching or other mechanisms may be provided anywhere along the length of the tether to extend or retract the tether. Any of these mechanisms may be used to control the length of a tether.

[0049] The mechanisms may be power controlled (e.g., powered winches) or hand- controlled (e.g., winding winches by hand). Also, such mechanisms may be manually operated by a user, or may be automatically adjusted by a controller. The mechanisms can be controlled locally or remotely. Multiple mechanisms may be controlled from a central location. Multiple tether lengths may be controlled in order to assist with positioning an aerostat. Any discussions of winches or any other attachment mechanisms may apply to any other type of attachment mechanisms.

[0050] Preferably, a winch (e.g., 150, 170, 190, 210), or any other mechanism that may connect the tether to the ground 50 may have a fixed location relative to the ground.

Alternatively, a winch or other connection mechanisms may move relative to the ground. For example, they may be placed on tracks that may enable them to move laterally or vertically with respect to the ground. Any movement with respect to the ground may be controllable.

[0051] In some embodiments, a tower 10 may start off at a substantially horizontally position, and be lifted using the aerostat 110 to a substantially vertical position. Alternatively, the tower 10 may start off at an angle, e.g., at a 5 degree, 10 degree, 15 degree, 30 degree, 45 degree, 60 degree angle relative to a horizontal orientation. The tower 10 may even start off below a horizontal orientation.

[0052] The lifting force from the aerostat 110 may create a rotational moment in the tower 10 around the axis of the hinge 20. As the tower 10 rises the rear winch 170 may increase the length of the rear tether 160. As the tower 10 rises the front winch 150 may decrease the length of the front tether 140. As the tower 10 rises the left winch 190 may increase the length of the left tether 180. As the tower 10 rises the right winch 210 may also increase the length of the right tether 200. Any tethers may be increased or decreased in length to keep the tethers relatively taut as the tower is lifted, while allowing the freedom to be lifted.

[0053] In some embodiments, unlike the other tower tilting systems depicted in Figure 1, Figure 2, and Figure 3, the front tether 140, rear tether 160, left tether 180, and right tether 200 do not apply forces to the tower 10 in order to induce a rotational moment in the tower 10 about the axis of the hinge 20. Rather the front tether 140, rear tether 160, left tether 180, and right tether 200 control the motion of the aerostat 110 and tower 10. In particular the front tether 140, rear tether 160, left tether 180, and right tether 200 resist the force of ground winds on the components of the system, in particular the force of ground winds on the aerostat 110. The tethers may be connected to the aerostat in a manner which may assist with controlling the aerostat position without exerting a rotational moment on the tower.

[0054] In some other implementations, a pulling force in the front tether 140 and front winch 150 may be used to induce a rotational moment in the tower 10 about the axis of the hinge 20 in addition to the lifting force provided by the aerostat 110. In some instances, the tethers may be connected to the aerostat only, may be connected to the tower, may be connected where the aerostat and tower interface, or any combination thereof. A tower may be raised by a lifting force from a buoyant aerostat and/or by a rotational moment generated by one or more tether. Thus, a tower may be raised by having a hinged end with a fixed position (or alternatively a hinged end that may only move on a restricted path), and a free end 120 that may experience a lifting force from an aerostat and/or a pulling force from a tether.

[0055] In some implementations, a pulling force in the rear tether 160 and rear winch 170 may be used to resist the rotational moment in the tower 10 about the axis of the hinge 20. Resisting rotation of the tower 10 may be necessary when the tower is nearly upright and the center of gravity of the tower 10 passes from one side of the axis of rotation of the hinge 20 to the other side of the axis of rotation of the hinge 20.

[0056] Similarly, in some implementations, the left tether 180 and/or right tether 200 may apply pulling or stabilizing forces to the tower in a direction perpendicular to the axis of the hinge. The left and right tethers may be kept taut to help stabilize the tower and may provide support in the sideways direction so that the tower does not move sideways.

[0057] Figure 6 depicts a modified tethering configuration in accordance with another embodiment of the invention. The configuration and operation of the system may be very similar to the configuration depicted in Figure 4 and Figure 5. The principle difference may be the orientation of left tether 180 and the right tether 200. In Figure 6, the left winch 190 and the right winch 210 may be eliminated. The left tether 180 can be of fixed length and attached to the ground 50 with the left anchor point 220. In this configuration the left tether 180 can be of fixed length and tower 10 will nonetheless be free to rotate about axis of the hinge 20. Similarly the right tether 200 can be of fixed length and attached to the ground 50 with the right anchor point 230. The right tether 200 can be of fixed length and tower 10 will nonetheless be free to rotate about axis of the hinge 20. The right and left tethers may be aligned so that they form a horizontal axis along with the hinge. The right tether, left tether, and hinge may be on the rotational axis of the tower hinge. This horizontal axis may be substantially perpendicular to an axis formed with the front winch 150, rear winch 170, and hinge. The right and left tethers may remain relatively taut to provide stability and sideways support to the tower as it may rotate into an upright position.

[0058] In some implementations, particularly ones where and the left anchor point 220 can be positioned close to but not precisely on the extended rotational axis of the hinge 20, it may be necessary to attach the left tether 180 to the left winch 190 and extend and/or retract the left tether 180 in order to provide control of the aerostat 110 and tower 10 during the tilting process.

[0059] In some implementations, particularly ones where and the right anchor point 230 can be positioned close to but not precisely on the extended rotational axis of the hinge 20, it may be necessary to attach the right tether 200 to the right winch 210 and extend and/or retract the right tether 200 in order to provide control of the aerostat 110 and tower 10 during the tilting process.

[0060] Figure 7 depicts another implementation of a tethering configuration. The configuration may be similar to the one depicted in Figure 4 and Figure 5. This configuration may utilize three tethers. A principle difference may be the elimination of the front tether 140 and front winch 150. The left winch 190 is positioned on the ground such with the tower 10 in the horizontal orientation the left tether 180 connecting left winch 190 to the tower 10 at the tower top 120 crosses over the axis of rotation of the hinge 20. Likewise, the right winch 210 is positioned on the ground such that with the tower 10 in the horizontal orientation the right tether 200 connecting the right winch 210 to the tower 10 at the tower top 120 crosses over the extended axis of rotation of the hinge 20.

[0061] Thus, the left winch 190 and the right winch 210 may be on one side of the extended axis of rotation of the hinge 20 while the rear winch 170 may be on the other side. In some instances, the left and right winches may be on a front side of the axis of rotation, in which the tower is raised from a rear side to an upright position. Alternatively, one winch may be provided on a front side of the axis of rotation, and two winches maybe on the rear side, in which the tower is raised from a rear side to an upright position.

[0062] Figure 8 and Figure 9 depict another tower lifting configuration. This configuration may be similar to the one depicted in Figure 4 and Figure 7. In this configuration, rather than tilting the entire tower in one piece, the tower may have a fixed lower portion 240 and a rotating upper portion 250. The fixed lower portion 240 may be in an essentially vertical orientation and may be attached at one end to the ground 50 and may be attached at the other end to the hinge 20. The rotating upper portion 250 may be attached at one end to the hinge 20 and may be attached at the other end to the aerostat 110 at the aerostat base 130. In other words, the hinge 20 may connect the fixed lower portion 240 and the rotating upper portion 250. The lifting process may proceed in a fashion essentially similar the lifting processes described above with a difference being that the lifting force from the aerostat 110 may create a rotational moment in only the rotating upper portion 250 around the axis of the hinge 20 and the fixed lower portion 240 may remain essentially motionless. After the lifting process is completed, the rotating upper portion 250 may be kept in a roughly vertical orientation by means of a locking mechanism in the hinge 20, the addition of stays, bolting the upper portion to the lower portion of the tower, or any number of other means or combination thereof at which point the aerostat 110 and/or the hinge 20 may be removed.

[0063] Figure 8 shows an example of a two-part tower lifting configuration where the left winch 190 and the right winch 210 for the left tether 180 and right tether 200 respectively are located on the other side of the rear winch 170. The upper portion of the tower may be rotated so that the tower top of the upper portion crosses over the extended axis of rotation of the hinge 20. This provides an example of a three tether configuration. Four tethered configurations, such as those illustrated in Figure 5 or Figure 6 may also be incorporated into a two-tower lifting configuration. Anchors or winches for any number of tethers (e.g., two, three, four, five, six, seven, eight, or more tethers) may be located anywhere around the tilt tower, on any side of the extended axis of rotation about the hinge. In some embodiments, at least one anchor or winch may be provided on each side of the extended axis of rotation about the hinge.

[0064] Figure 9 provides a side view of a two-part tower lifting configuration in

accordance with an embodiment of the invention. The aerostat 110 may be connected to a first end up of an upper portion 250 of the tower which may be connected to a hinge 20. A lower portion 250 of the tower may be connected to the hinge 20 and the ground 50. In preferable embodiments, the lower portion is substantially fixed and does not rotate with respect to the ground. In alternative embodiments, the lower portion may rotate with respect to the ground and may have a hinge with respect to the ground. In some embodiments, the lower portion may be shorter than the upper portion. In other embodiments, the lower portion may be longer than the upper portion. In some embodiments, the lower portion and upper portion may have the same length.

[0065] In alternative embodiments of the invention, any number of sections may be provided to a tower with hinges therebetween. Similarly, any number of aerostats may be connected to any section of the tower to assist with raising the tower. For example, a tower can have one, two, three, four, five, six, seven, eight, or more portions. The portions may be hinged with respect to one another. One, two, three, four, five, six, or more aerostats may be connected to the tower. In some embodiments, aerostats may be connected to different portions of the tower. For example, a tower may have a fixed bottom portion, hinged middle portion, and hinged top portion. A first aerostat may be connected to the top of the top portion, and a second aerostat may be connected to the top of the middle portion at or near the hinge between the middle portion and the top portion. Once the various portions are lifted into place they may be kept in a fixed orientation by means of a locking mechanism in the hinge, the addition of stays, bolting the portions of the tower, or any number of other means or combination thereof, at which point the aerostat and/or the hinges may be removed. In preferable embodiments, the fixed orientation may be a roughly vertical orientation. In other embodiments, the fixed orientation may include any angle relative to a roughly vertical orientation.

[0066] In some embodiments, an aerostat may include a winch, or similar mechanism that may enable the aerostat to raise and/or lower a payload with respect to the aerostat. The winch may be attached to the aerostat at any position on the aerostat. In some embodiments, the winch may be provided at the bottom of the aerostat. In other embodiments, the winch may be in a bottom region of the aerostat, or along a side or top of the aerostat. In some instances, the winch may be suspended below the aerostat, or attached to the payload or a tether connecting the payload.

[0067] A winch may enable the length of a line connecting to a payload to increase and/or decrease as the winch turns. Other mechanisms may be provided that may allow the length of a line connecting to a payload to increase and/or decrease (e.g., as the line is extended or retracted). As discussed, in some embodiments, a winching mechanism, or other mechanism may be mounted on the aerostat that may enable the length of the payload bearing line to increase and/or decrease. Alternatively, winching or other mechanisms may be provided anywhere along the length of the line to raise or lower the payload with respect to the aerostat. Any of these mechanisms may be used to control the relative position of a payload with respect to the aerostat.

[0068] The mechanisms may be power controlled (e.g., powered winches) or hand- controlled (e.g., winding winches by hand). Also, such mechanisms may be manually operated by a user, or may be automatically adjusted by a controller. The mechanisms can be controlled locally or remotely. Multiple mechanisms may be controlled from a central location. Multiple payload line lengths may be controlled in order to assist with positioning a payload with respect to an aerostat.

[0069] The payload may be any object that may be raise and/or lowered with respect to the aerostat and/or other frame of reference. For example, the payload may be a heavy object, which may include, but is not limited to, objects weighing on the order of 0.1 tons, 0.5 tons, 1 ton, 5 tons, 10 tons, 20 tons, 50 tons, 100 tons, 500 tons, 1000 tons, or more. In some instances, a payload may be suspended by an aerostat. In one example, a payload may be completely suspended by the aerostat so that it does not contact the ground. In some instances, the payload may be contacting the ground or other reference surface, while being partially suspended by the aerostat. For example, the payload may be a top portion of a tilt tower. An aerostat may utilize a winch or similar mechanism to raise and/or lower a top portion of a tilt tower, so that the tilt tower is tilted upwards or downwards. In some embodiments, the aerostat may be static with respect to the ground or other reference surface while the payload is raised and/or lowered. In other embodiments, the aerostat may move with respect to the ground or other reference surface while the payload is raised and/or lowered.

[0070] One aspect of the invention may be directed to a method of raising a tower. The method may comprise the step of providing a tower in a first position. As previously discussed, the first position may be a substantially horizontal position. Alternatively, the first position may be at an angle with respect to a horizontal position. The tower may have a first end and a second end. A buoyant aerostat may be connected to the tower at the second end. The tower may be lifted at the second end using the buoyant aerostat, so that the first end remains at substantially the same location (or alternatively so that the first end moves on a restricted path). One or more tethers may have a first end connected to a reference frame, such as the ground or other relatively fixed structure. The tethers may also have a second end, which may be connected to the aerostat and/or the tower. The tethers may assist with guiding the aerostat and tower into the desired position. The tower may be raised to a second position. As previously discussed, the second position can be a substantially vertical position.

Alternatively, the second position may be at an angle to a vertical position. In some embodiments, the tethers may also provide force to assist with raising the tower to the second position, while in other embodiments they may not be used to provide a rotational moment.

[0071] The method for raising a tower may also be applied to lowering a tower in a controlled manner. For example, when lowering a tower, the tower may start off in a position that may be substantially vertical or at some angle to a vertical orientation. The buoyant aerostat may be used to provide sufficient lifting force to keep the tower moving in a controlled manner. In some instances, a tether may be used to pull the tower downwards while the aerostat may keep the top of the tower relatively suspended.

[0072] When raising or lowering the tower, one or more winches may be controlled to adjust tether length as desired. In some embodiments, an aerostat may have a relatively fixed buoyancy, while in other embodiments, the buoyancy of the aerostat may be adjusted to provide the desired amount of lifting force. Any of these parameters may be adjusted to lift and/or lower the tower at a desired rate.

[0073] It should be understood from the foregoing that, while particular implementations have been illustrated and described, various modifications can be made thereto and are contemplated herein. It is also not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the preferable embodiments herein are not meant to be construed in a limiting sense. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. Various modifications in form and detail of the embodiments of the invention will be apparent to a person skilled in the art. It is therefore contemplated that the invention shall also cover any such modifications, variations and equivalents.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A system for raising a tower, the system comprising:

the tower, with a hinged end;

a buoyant aerostat attached to the tower at a free end opposite the hinged end, wherein the buoyant aerostat is configured to lift the free end of the tower while the hinged end remains at a substantially fixed location;

at least one tether connecting the buoyant aerostat to a reference surface.

2. The system of claim 1 wherein the length of the at least one tether is adjustable.

3. The system of claim 2 wherein the length of the at least one tether is adjustable by a winch.

4. The system of claim 1 wherein a plurality of tethers connect the buoyant aerostat to a surface at different surface attachment points.

5. The system of claim 4 wherein at least one tether is located on one side of an extended axis of rotation about the hinge, and at least one tether is located on the other side of an extended axis of rotation about the hinge.

6. The system of claim 4 wherein at least one tether is anchored along the extended axis of rotation about the hinge.

7. The system of claim 1 wherein the aerostat is attached to the free end is freely rotatable with respect to the tower.

8. The system of claim 1 wherein the tower is pre-assembled.

9. A system for raising a tower, the system comprising:

the tower connected to a reference surface, having one or more tower portions with a hinged end; and at least one buoyant aerostat attached to the tower portion at a location other than the hinged end, wherein the buoyant aerostat is configured to lift at least part of the tower portion while the tower remains connected to the reference surface.

10. The system of claim 9 wherein the tower includes a lower portion connected to the reference surface and an upper portion connected to the lower portion at a hinged end.

11. The system of claim 10 wherein the aerostat is attached a free end of the upper portion opposite the hinged end of the lower portion.

12. The system of claim 9 further comprising a plurality of tethers connecting the buoyant aerostat to different locations at the reference surface.

13. The system of claim 12 wherein at least one of the tethers is configured to increase or decrease in length.

14. The system of claim 13 wherein the tethers increase or decrease in length by use of a winch.

15. A method of raising a tower, the method comprising:

providing a tower in a substantially horizontal position, wherein the tower has a first end and a second end;

connecting a buoyant aerostat to the tower at the second end;

lifting the tower at the second end using the buoyant aerostat, so that the first end remains at substantially the same location.

16. The method of claim 15 further comprising connecting the buoyant aerostat to at least one tether.

17. The method of claim 16 further comprising adjusting the length of the tether with a winch.

18. The method of claim 15 further comprising keeping the tower in a fixed orientation once it has been lifted.

19. The method of claim 18 wherein the tower is kept in a fixed orientation by at least one of the following: a locking mechanism in the hinge, the addition of stays, or bolting the tower.

20. The method of claim 19 further comprising removing the aerostat once the tower is in a fixed orientation.