Leaf-inspired energy device could power tech on Mars

Developed at Warwick University, the energy harvester came about off the back of an annual challenge given to engineering students where they had to figure out why aspen leaves quiver in even the slightest breeze. After setting the undergraduates the task for several years, researchers Sam Tucker Harvey, Dr Igor Khovanov and Dr Petr Denissenko decided to investigate if the unique phenomenon behind the leaf movement could be used to harness energy.

The aspen leaf has a flat stem that facilitates a large amplitude quiver even at low wind speeds. The team mimicked the shape of the leaf using mathematical modelling, then tested its device in a wind tunnel. A cantilever beam acted like the flat stem, while a curved blade tip with a circular arc cross-section mimicked the leaf’s body.

Orienting the blade perpendicular to the wind flow direction allowed the harvester to produce self-sustained oscillations at uncharacteristically low wind speeds, just like an aspen leaf. The tests showed that the airflow becomes attached to the rear face of the blade when the blade's velocity becomes high enough, performing more akin to an aerofoil compared with other device shapes typically used for wind energy harvesting.