Patent Abstract:
A system and method of mounting a wind turbine to the top of a structure which is not designed to support the possible moment exerted in the structure by the wind turbine. The mount may be connected to a base of the structure by one or more tension members which may exert a downward force on a turbine mount, where the force is selected to correspond to a moment calculated to be possibly exerted on the structure by wind acting on the wind turbine.

Full Description:
BRIEF DESCRIPTION OF THE INVENTION 
       [0001]    The invention described herein provides a methodology for mounting a wind turbine device to non-turbine purpose built structures (such as farm silos) to eliminate the cost of a purpose built wind turbine tower and the interference of typical guy wires. Non-turbine purpose built structures are classified into two categories. Structures that are strong only in compression (e.g. concrete) and structures that are relatively strong in both compression and tension (e.g. steel). The invention defines a continuous compression solution for compression only structures and a distributed mounting structure solution for structures capable of both compression and tension. 
         [0002]    The use of non-turbine purpose built structures is desirable due to availability and cost; however, by definition these structures were not designed to handle the forces implied by a wind turbine which can be quite substantial. The invention provides the appropriate mechanisms to securely mount a wind turbine device to non-turbine purpose built structures such that the forces generated by the wind turbine are properly distributed within the capabilities of the existing structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    The accompanying drawing figures, which are incorporated in and constitute a part of the description, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. A brief description of the figures is as follows: 
           [0004]      FIG. 1  is a perspective view of wind turbines mounted to the top of non-turbine purpose built structures, for example, different types of silos, according to the present disclosure. 
           [0005]      FIG. 2  is a schematic diagram of a prior art self supporting tubular structure with a mass foundation with a wind turbine mounted to the top. 
           [0006]      FIG. 3  is a schematic diagram of a prior art non-self supporting tubular structure using mass foundations and requiring guy wires to counter wind loads with a wind turbine mounted to the top. 
           [0007]      FIG. 4  is a schematic diagram of a prior art self supporting open truss structure with a mass foundation with a wind turbine mounted to the top. 
           [0008]      FIG. 5  is a schematic diagram of a prior art non-self supporting open truss structure using mass foundations and requiring guy wires to counter wind loads with a wind turbine mounted to the top. 
           [0009]      FIG. 6  is a schematic diagram of concrete non-turbine purpose built silos with a wind turbine mounted to the top of each silo using a mount according to the present disclosure, with the tension members omitted to illustrate the loads placed on the silo by wind loads. 
           [0010]      FIG. 7  is a schematic diagram of concrete silos and turbines of  FIG. 6 , with tension members added to counteract tensile forces in the silos created by wind loads. 
           [0011]      FIG. 8  is a schematic diagram of a prior art steel or aluminum non-turbine built silo with a wind turbine mounted to the top. 
           [0012]      FIG. 9  is a schematic diagram of a steel or aluminum non-turbine built silo with a wind turbine mounted to the top with a mount according to the present invention. 
           [0013]      FIG. 10  is a overhead schematic view comparing the footprint of a guy wire supported structure with a wind turbine mounted on top with a silo with a turbine mounted to the top with a mount according to the present disclosure. 
         DEFINITIONS, TERMS, ELEMENTS 
         [0014]    Wind turbine—a device used for converting wind energy into electrical energy 
           [0015]    Purpose built wind turbine tower—a structure which is erected solely for the purposes of mounting a wind turbine 
           [0016]    Non-turbine purpose built structures—a structure suitable for mounting a wind turbine which has been previously built (or will be built) for an application or use other than the mounting of a wind turbine. Examples are silos, stacks, water towers, ski lift towers, etc. . . . 
           [0017]    Guy wires—series of cables used to connect the top of a tower to the ground typically at a 45 degree angle 
           [0018]    Continuous compression—a mounting methodology defined within this invention to place a structure into sufficient compression such that the forces generated from a wind turbine mounted on its top will never put any part of the original structure into tension. 
           [0019]    Distributed mounting structure—a mounting methodology defined within this invention to strengthen structures sufficiently such that the forces generated from a wind turbine mounted on its top will never push any part of the original structure beyond its capabilities. 
         BACKGROUND OF THE INVENTION (PRIOR ART) 
         [0020]    Typically, a purpose built turbine tower (engineered pole or truss tower) is used to elevate a wind turbine to the appropriate height. There are two general types of these structures: free standing and guy wire supported. Free standing structures necessitate a large mass (usually concrete) to counter the moment created by the wind force. Guy wire structures use much smaller tube or truss structures with a similar, but smaller mass in addition to tensioned guy wires anchored to the earth to counter the wind generated moments. 
           [0021]    The figures herein depict the most common types of wind mill towers/structures selected from among the myriad possible existing structures that might be used for turbine mounting according to the present disclosure. The following description is exemplary only and is not intended to limit in any way the type and nature of existing structures that may be used to mount a turbine according to the present disclosure. 
         APPLICABLE PATENT PRIOR ART 
         [0022]      
           [0000]    
         
           
                 
                 
                 
               
             
                 
                     
                 
               
               
                 
                   U.S. Pat. No. 4,524,528 
                   Wind powered 
                   Jun. 25, 1985 
                 
                 
                     
                   grain drying apparatus 
                 
                 
                   U.S. Pat. No. 5,419,683 
                   Wind turbine 
                   May 30, 1995 
                 
                 
                   U.S. Pat. No. 6,157,088 
                   Wind energy system 
                   Dec. 5, 2000 
                 
                 
                     
                 
               
            
           
         
       
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    Reference will now be made in detail to exemplary aspects of the present invention which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0024]    Mounting a wind turbine to a non-turbine purpose built structure will likely be problematic due to the large moments created by the wind force on the wind turbine. Most existing structures that might be desirable for mounting a wind turbine (silos, stacks, water towers, ski lift towers, etc. . . . ) were not designed for this purpose and did not include such structural limitations in their initial design parameters. The moments or loads created by the wind turbine and the force of the wind acting on the turbine may cause tension in one part of the structure and compression on the opposite side. The locations of the tension and compression loads will change with the prevailing wind direction. The present disclosure describes but is not limited to two preferred mechanisms for mounting the wind turbine such that the structure is properly strengthened to handle the additional moments produced by the wind turbine. To explain the invention, non-turbine purpose built structures have been classified into two categories: 
         [0025]    1) Structures which are very strong in compression but not tension such as but not limited to silos made from poured concrete, block, brick, or stave. 
         [0026]    2) Structures which are relatively strong in both compression and tension such as but not limited to silos made from steel, aluminum, or wood. 
         [0027]      FIG. 6  shows the forces created on structures such as a stave concrete silo  100  when a wind turbine  102  and a mount  103  according to the present disclosure is mounted to a top  104  of silo  100 . Mount  103  may include a plurality of legs or strength members  105  to spread the weight of the turbine and any moment generated by wind acting on the turbine to top of the wall of the silo.  FIG. 6  also shows the similar forces created on a structure such as a poured concrete silo  110  when a wind turbine  102  and a mount  103  are mounted to a top  112  of silo  110   
         [0028]    A first side  106  of silo  100  which faces into the wind is put into tension while an opposite side  108  of silo  100  may be put into compression. A first side  114  of silo  110  which faces into the wind may be similarly put into tension while an opposite side  116  may be put into compression. For concrete, block, brick, or stave structures which are strong in compression (and not tension), the tensile forces will likely destroy the silo over time. 
         [0029]    For structures strong and/or stable in compression, the present disclosure provides continuous compression on the structure such that no portion of the structure ever goes into tension.  FIG. 7  shows one of many embodiments according the present disclosure that preloads compression-resistant and tension-intolerant structures so that the structures may be kept in continuous compression. Mount  103  on top of silo  100  may be connected to a base  120  of the silo by a plurality of anchor cables acting as tension members  122 . While mount  103  is shown as a four legged mount that engages top  104  at four points generally evenly spaced apart about the circumference, it is anticipated that more or fewer legs may be used. Alternatively, mount  103  may form a generally unbroken cover over top  104  of silo  100  and spread the load evenly about the entire top edge of the walls of the silo. 
         [0030]    Once the mount has been placed on the top of the silo and secured to the base of the silo, the tension members or anchor cables  122  may be loaded in tension so that the cables urge the mount downward onto top  104  of silo  100 . The tension in anchor cables  122  is preferably set to a sufficient tension so that any wind loads that might otherwise place one side of the silo into tension are counteracted. For example, the tension in cables  122  may be selected to be greater than the maximum force induced by the wind turbine such that the structure is kept in continuous compression, regardless of wind speed or direction. This will ensure that structures strong in compression will never be stressed in a manner which may deteriorate or destroy the structure. 
         [0031]    In  FIG. 7 , silo  110  may also be similarly configured with mount  103  anchored to base  120  by anchor cables  122  that are tensioned sufficiently to prevent any portion of the silo from being placed under tension by wind loads acting on the turbine or the mount. 
         [0032]      FIG. 8  shows the forces created on an exemplary structure such as steel or aluminum silo  130  when a wind turbine  102  is mounted to a top  132  of the silo. Steel or aluminum structures are relatively strong in both compression and tension; however, they may not be capable of handling the additional forces induced by a wind turbine. Particularly for a structure such as a silo  130  that was designed to contain bulk items, the upper portions of the structure may not have been designed to handle the magnitude and direction of loads that a turbine may exert on the silo. 
         [0033]    For structures relatively strong in both compression and tension, the present disclosure provides a distributed mounting structure within or on the structure to ensure the forces induced by the wind turbine never exceed the capacity of any portion of the structure.  FIG. 9  shows an embodiment of a mount  134  for mounting a turbine  102  to the top  132  of a non-turbine purpose built structures which may distribute the loads from the turbine and the wind loads to ensure the forces induced by the wind turbine do not exceed the capacity of the original structure. There may be a plurality of strength members  136  that fit over the existing top structure of silo  130  and distribute the increased loads due to the turbine across the top to the sides of the structure. Additional strength members  136  (if required) within the silo may be part of the distributed mounting structure  134  to help ensure that the structure  130  is capable of handling the additional moments and other loads created by the wind turbine. As the structure itself is capable of carrying both tensile and compression loads, it may not be necessary to provide pre tensioned anchor cables such as cables  122 . However, depending on the strength of the existing structure and the weight and potential wind loads of turbine  102 , it may be desirable to have strength members  136  that extend to the base  120  to provide additional support to the walls of silo  130 . 
         [0034]    As compared with purpose built wind turbine towers using guy wires, the use of non-turbine purpose built structures may reduce the footprint size.  FIG. 10  shows a top view comparing a guy wire tower  140  mount to a silo  142  mount. The footprint size (interference area) of the guy wire mount structure is significantly larger that that of the silo structure, due to a dispersed position of a plurality of guy wires  144  required to support the tower  140  and their anchor points  146 , as compared to the footprint of an outer wall  148  of silo  142 . Depending on the location of the wind turbine site, the footprint size may be very important to the owner/operator of the wind turbine. 
         [0035]      FIG. 5  illustrates a side view of tower  140 .  FIG. 4  illustrates 
       Alternate Embodiments 
       [0000]    
       
         1. Non-turbine purpose built structures suitable for mounting a wind turbine that have not been mentioned specifically within this disclosure 
         2. Alternative methods or tensile structures for applying continuous compression to a concrete, block, brick, or other type of construction strong in compression. 
         3. Alternative methods of applying a distributive mounting structure to a steel, aluminum, or other type of construction relatively strong in both tension and compression. 
       
     
       ADVANTAGES OF THE INVENTION COMPARED TO PRIOR ART 
       [0039]    The major advantage of using non-turbine purpose built structures is cost. Additional advantages are as follows:
       Structures are in place today (or planned) thereby reducing time and costs of installation.   Structures usually have high power electrical infrastructure already in place, particularly farms which already have a large connection to the power grid to provide electrical power to the various electric motors used in typical farm operations.   Structures do not require external guy wires thereby reducing the footprint size.       
 
         [0043]    While the invention has been described with reference to preferred embodiments, it is to be understood that the invention is not intended to be limited to the specific embodiments set forth above. Thus, it is recognized that those skilled in the art will appreciate that certain substitutions, alterations, modifications, and omissions may be made without departing from the spirit or intent of the invention. Accordingly, the foregoing description is meant to be exemplary only, the invention is to be taken as including all reasonable equivalents to the subject matter of the invention, and should not limit the scope of the invention set forth in the following claims.

Technology Classification (CPC): 5