title: Wind Energy Conversion by Plant-Inspired Designs.
abstract: In 2008 the U.S. Department of Energy set a target of 20% wind energy by 2030. To date, induction-based turbines form the mainstay of this effort, but turbines are noisy, perceived as unattractive, a potential hazard to bats and birds, and their height hampers deployment in residential settings. Several groups have proposed that artificial plants containing piezoelectric elements may harvest wind energy sufficient to contribute to a carbon-neutral energy economy. Here we measured energy conversion by cottonwood-inspired piezoelectric leaves, and by a "vertical flapping stalk"-the most efficient piezo-leaf previously reported. We emulated cottonwood for its unusually ordered, periodic flutter, properties conducive to piezo excitation. Integrated over 0°-90° (azimuthal) of incident airflow, cottonwood mimics outperformed the vertical flapping stalk, but they produced << daW per conceptualized tree. In contrast, a modest-sized cottonwood tree may dissipate ~ 80 W via leaf motion alone. A major limitation of piezo-transduction is charge generation, which scales with capacitance (area). We thus tested a rudimentary, cattail-inspired leaf with stacked elements wired in parallel. Power increased systematically with capacitance as expected, but extrapolation to acre-sized assemblages predicts << daW. Although our results suggest that present piezoelectric materials will not harvest mid-range power from botanic mimics of convenient size, recent developments in electrostriction and triboelectric systems may offer more fertile ground to further explore this concept.
authors.affiliation: Department of GDCB, Iowa State University, Ames, IA, United States of America.|Creodyne, LLC, 2410 NE 13th Ct, Ankeny, IA, United States of America.
authors.forename: Michael A
authors.identifier: http://orcid.org/0000-0002-0144-3570
authors.initials: MA
authors.lastname: McCloskey
authors.affiliation: Department of GDCB, Iowa State University, Ames, IA, United States of America.
authors.forename: Curtis L
authors.initials: CL
authors.lastname: Mosher
authors.affiliation: Department of GDCB, Iowa State University, Ames, IA, United States of America.|Creodyne, LLC, 2410 NE 13th Ct, Ankeny, IA, United States of America.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Henderson
mesh_terms: D004735:Energy Transfer; D006801:Humans; D008962:Models, Theoretical; D018515:Plant Leaves / Q000502:physiology*; D010944:Plants / Q000737:chemistry*; D059205:Renewable Energy; D014919:Wind