The disclosure relates to vertical axis turbines comprising a blade support and two or more turbine blades. The blade support is configured to rotate about a central axis. The two or more turbine blades are secured to the blade support and configured to orbit the central axis during rotation of the blade support around the central axis. Each of the two or more turbine blades includes a first edge opposed to a second edge. The first edge is rounded and the second edge is sharp relative to the first edge, and includes first and second sides that extend between the first and second edges. At least one of the first and second sides includes a hook shaped recess, is configured to pivot relative to the blade support about a pivot axis that is offset from and parallel to the central axis.