Patent ID: 8061993

Claim:
A vertical axis turbine comprising a plurality of blades rotatably disposed around an axis of rotation at a plurality of blade locations, each blade being twisted at a first angle about its longitudinal axis, each blade having its distal ends located a predetermined distance from the axis of rotation, each blade being bent at one or more central locations along the longitudinal axis so the one or more central locations are the same predetermined distance from the axis of rotation as the distal ends, each blade having a foil cross section perpendicular to the axis of rotation for maintaining unidirectional rotation of that blade about the axis of rotation in a fluid flow, and each blade having its longitudinal axis tilted at a second angle with respect to the axis of rotation, wherein the second angle is approximated by the equation β=sin−1[2 r ·sin(π/ n )/Length], wherein β is the second angle, r is the predetermined distance from the axis of rotation, n is the number of blade locations, and Length is the length of the longitudinal axis of each blade, or one or more blades, at each blade location.