Insect Power Drag

Mayfly swarm.

Insects are good at avoiding collisions with stationary objects. Insects are not as good at avoiding collisions with moving objects such as car windshields. Insects also collide with and stick to the blades of wind turbines. A study in 2001* found that insects can halve wind turbine power. The study began as an investigation of unexplained power loss. Insects fly during periods of high humidity and low wind speed. Under these conditions, insects collide with and accumulate on the blades of the wind turbine. At high wind speeds, the aerodynamic flow over the smooth leading edge of a turbine blade becomes critical to power output. Insects collected the blade present a rough surface and reduce power output at high wind speeds. Power returns once the blades are cleaned.

*Gustave P. Corten & Herman F. Veldkamp. Aerodynamics: Insects can halve wind-turbine power. Nature 412, 41-42 (5 July 2001)
doi:10.1038/35083698