Vertical array wind turbine

Abstract

A wind turbine with an array of rotors arranged at various heights. Each rotor is optimized for the height at which it is located. Optimization of each rotor could include selection of rated power, solidity, tip speed, blade twist, blade taper, or rotor diameter. Each rotor can also be operated in a manner that is optimized for the wind speed it experiences. Optimized operation parameters could include blade pitch angle or rotor speed.

1 . A wind turbine comprising: 
 a tower;    a plurality of rotors attached to said tower at a plurality of heights wherein each rotor is optimized for the wind speed at the height at which it is attached whereby said wind turbine is capable of efficiently extracting energy from the wind where wind speed varies with height.    
     
     
         2 . The wind turbine of  claim 1  wherein each said rotor has a rated power that is selected based on the annual average wind speed at the height at which it is attached.  
     
     
         3 . The wind turbine of  claim 1  wherein each said rotor has a plurality of blades and the ratio of the planform area of said blades to the swept area of each said rotor is selected based on the annual average wind speed at the height at which it is attached.  
     
     
         4 . The wind turbine of  claim 1  wherein each said rotor has a rotor diameter that is selected based on the annual average wind speed at the height at which it is attached.  
     
     
         5 . The wind turbine of  claim 1  further comprising a wind speed sensor associated with each of said rotors for measuring the wind speed at a respective rotor wherein the operation of each said rotor is controlled for optimum performance for its measured wind speed.  
     
     
         6 . The wind turbine of  claim 5  further comprising a controller which receives data from each of said wind speed sensors and controls the operation of each said rotor based on the measured wind speed at said rotor.  
     
     
         7 . The wind turbine of  claim 6  wherein said controller adjusts the blade pitch of each said rotor based on the measured wind speed at said rotor.  
     
     
         8 . The wind turbine of  claim 7  wherein said controller adjusts the rotational speed of each said rotor based on the measured wind speed at said rotor.  
     
     
         9 . A method of extracting energy from wind comprising: 
 providing a tower;    supporting a plurality of rotor driven turbines on said tower at a plurality of heights; and    optimizing each said rotor driven turbine for the wind-speed at the height at which it is supported whereby said wind turbine efficiently extracts energy from the wind where wind speed varies with height.    
     
     
         10 . The method of  claim 9  wherein the step of optimizing each said rotor driven turbine comprises selecting a rated power for each turbine based on the annual average wind speed at the height at which it is supported.  
     
     
         11 . The method of  claim 9  wherein the step of optimizing each said rotor driven turbine comprises providing each said rotor with a plurality of blades and selecting the ratio of the planform area of said blades to the swept area of each said rotor based on the annual average wind speed at the height at which it is supported.  
     
     
         12 . The method of  claim 9  wherein the step of optimizing each said rotor driven turbine comprises selecting a rotor diameter based on the annual average wind speed at the height at which it is supported.  
     
     
         13 . The method of  claim 9  further comprising the step of providing a wind speed sensor associated with each of said turbines to measure the wind speed at a respective turbine and further comprising the step of controlling each said turbine for optimum performance for its measured wind speed.  
     
     
         14 . The method of  claim 13  further comprising the step of providing a controller which receives data from each of said wind speed sensors and controlling the operation of each said turbine based on the measured wind speed.  
     
     
         15 . The method of  claim 14  wherein the step of controlling the operation of each said turbine comprises using said controller to adjust the blade pitch of each said rotor based on the measured wind speed at the turbine location.  
     
     
         16 . The method of  claim 14  wherein the step of controlling the operation of each said turbine comprises using said controller to adjust the rotational speed of each said rotor based on the measured wind speed at the turbine location.