Reducing bird collision risk per megawatt by introducing longer wind turbine blades

Abstract

Renewable energy, including wind energy, remains one of the most effective options for controlling global warming. However, increasing wind turbine size (mainly blade size) implies expanding the blade swivel range (rotor sweep zone), and concerns have been raised about a possible increase in the number of bird collisions with the rotating blades. Conversely, an increase in turbine size, accompanied by a reduction in rotation speed might reduce the avian collision risk. The change in the number of collisions with increasing wind turbine size was analyzed using simple collision risk models. The results showed that with an increase in the length of the wind turbine blade, although the number of collisions per turbine increased monotonically, the number of collisions per megawatt generated decreased as a hyperbolic function. These models involved some assumptions for simplicity; therefore, their validity requires testing in wind-power replacement projects.