Wind Energy Conversion by Plant-Inspired Designs
Fig 7
Directional sensitivity of power output from vertical flapping stalk and cottonwood leaf models.
Power was maximal for both systems when PVDF petiole was oriented edge-on into wind (8.9 vs. 7.5 knots for flapper vs. cottonwood) and decayed with increase in azimuthal angle. Max power was greater but decayed more steeply for vertical flapping stalk. RL = 10 MΩ both systems.