Screw turbine and method of power generation

Abstract

A screw turbine comprising a helical turbine blade mounted for axial rotation, a mount associated with the helical turbine blade and mounting the helical turbine blade for axial rotation, and a generator associated with the helical turbine blade which converts energy imparted to the helical turbine blade to electricity, wherein the diameter of the helical turbine blade is less than the lead of the helical turbine blade and wherein said screw turbine is adapted to permit lateral exchange of fluid in use.

1 . A screw turbine comprising:
 a helical turbine blade mounted for axial rotation;   a mount associated with the helical turbine blade and mounting the helical turbine blade for axial rotation; and   a generator associated with the helical turbine blade which converts energy imparted to the helical turbine blade to electricity,   wherein the diameter of the helical turbine blade is less than the lead of the helical turbine blade and wherein said screw turbine is adapted to permit lateral exchange of fluid in use.   
     
     
         2 . A screw turbine according to claim,  1 , wherein said helical turbine blade of said screw turbine is unsheathed in use to permit lateral exchange of fluid. 
     
     
         3 . A screw turbine according to  claim 1 , wherein a ratio of diameter and lead of said helical turbine blade is 1:8. 
     
     
         4 . A screw turbine according to  claim 1 , wherein said helical turbine blade has a lead angle of from about 50-75°, for example of about 60-75°. 
     
     
         5 . A screw turbine according to  claim 1 , wherein the helical turbine blade is an axleless helix. 
     
     
         6 . A screw turbine according to  claim 1 , wherein said at least one mount includes a coupling provided with bearings which facilitates rotation of the helical turbine blade about its longitudinal axis. 
     
     
         7 . A screw turbine according to  claim 1 , wherein a drive shaft associated with the blade is engaged with gearing that engages the generator to produce electricity, the gearing preferably operating at low revolutions (revs) and high torque. 
     
     
         8 . A helical turbine blade for a screw turbine, said helical turbine blade comprising an axleless helix, the diameter of said axleless helix being less than the lead of said axleless helix. 
     
     
         9 . A helical turbine blade according to  claim 8 , wherein a ratio of diameter and lead of said helical turbine blade is 1:8. 
     
     
         10 . A helical turbine blade according to  claim 8 , wherein said helical turbine blade has a lead angle of from about 50-75°, for example of about 60-75°. 
     
     
         11 . A method of power generation comprising:
 submerging a screw turbine provided with a helical turbine blade in a body of moving water; and   converting energy imparted to the helical turbine blade to mechanical or electrical power,   wherein said screw turbine is adapted to permit lateral exchange of water as said helical turbine blade is rotated by said moving water.   
     
     
         12 . A method of power generation according to  claim 11 , wherein said screw turbine is submerged unsheathed to permit lateral exchange of water as said helical turbine blade is rotated by said moving water. 
     
     
         13 . A method according to  claim 11 , wherein said energy imparted to the helical turbine blade is converted to electricity through a generator. 
     
     
         14 . A method according to  claim 11 , wherein the diameter of the helical turbine blade is less than the lead of the helical turbine blade, preferably said helical turbine blade comprises an axleless helix, the diameter of said axleless helix being less than the lead of said axleless helix. 
     
     
         15 . A method according to  claim 11 , wherein a ratio of diameter and lead of said helical turbine blade is about 1:8. 
     
     
         16 . A method according to  claim 11 , wherein said helical turbine blade has a lead angle of from about 50-75°, for example of about 60-75°