Means for reducing the weight of wind turbine structure needed to extract energy from the wind, comprising:
- a) Multiple blades, so supported within a space frame type structure that said blades can be far lighter in weight than blades of comparable size for a conventional horizontal axis wind turbine, in part by designing said blades in the form of multiple sequential segments supported on tensional members that extend radially outward under tension from a common horizontal axis of rotation to at least one perimeter ring whose design in turn allows said blades to force the extraction of power from the wind at a far higher initial RPM than the RPM of airfoil rotation.
- b) In a first such arrangement for taking off a useful power output, said tensional members extend out from a horizontal axis of rotation to a perimeter ring that has a typical rectangular cross section whose inner side has a centrally located gap that extends completely around said inner side of said perimeter ring, and that allows said airfoils to drive rotation of inflated rubber tires on wheels that run circumferentially along the inner and outer ring surfaces to either side of said centrally located gap. Rotation of said tires is then used to force the rotation of electrical generators and air compressors (?) at a far higher initial RPM than the rotation of the attached blade system. However, this first arrangement seems likely to incur problems in transferring the energy output of said electrical generators and air compressors down to ground level.
- c) In a second such arrangement for taking off a useful power output at the outer ends of the blades, said perimeter ring encloses a second, internal ring to which the ends of the blade connect, through said centrally located gap, to drive rotation of this second, internal ring through the interior of said perimeter ring that encloses said second, internal ring. This second, internal ring is then used to drive rotation of wheels attached to power producing elements distributed at intervals along the interior of the outer perimeter ring, as a means of producing a useful power output at a high initial RPM that is more readily transferable, via the outer perimeter ring, down to ground level, for transport to the point of use.
- d) In a second means for reducing turbine blade structural weight requirement, multiple stay cables extend from said blades, at intervals along their length, fore and aft to ancillary structure that can resist the wind's force with substantially greater economy of structure than is possible for the blades and tower of a conventional, cantilever beam blade wind turbine.
- e) A first part of said ancillary structure for resisting the wind's force may consist of fore and aft spars whose upper ends are the termini for stay cables converging from the blade system, and whose lower ends rest on a central, ground level pivot.
- f) A second part of said ancillary structure may consist of shroud cables that extend from the upper end of each diagonal spar down to mobile connections to an above ground level curb.
- g) A third part of said ancillary structure may consist of an above ground level curb that encircles said pivot at the base of the nested rings, at the radius of the upper ends of the diagonal spars, in order to support mobile means for resisting stay cable tension.
- h) A fourth part of said ancillary structure may consist of curb mounted jib cars having wheels that pull upward on a suitable element of the curb's cross section, for the purpose of resisting stay cable tension while remaining directly below the outer ends of this invention's two diagonal spars, as these spars rotate in azimuth with the blade system.