Kim, Shi HyeongSim, Hyeon JunHyeon, Jae SangSuh, DongseokSpinks, Geoffrey M.Baughman, Ray H.Kim, Seon Jeong2019-07-262019-07-262018-06-072045-2322https://hdl.handle.net/10735.1/6745The development of practical, cost-effective systems for the conversion of low-grade waste heat to electrical energy is an important area of renewable energy research. We here demonstrate a thermal energy harvester that is driven by the small temperature fluctuations provided by natural convection. This harvester uses coiled yarn artificial muscles, comprising well-aligned shape memory polyurethane (SMPU) microfibers, to convert thermal energy to torsional mechanical energy, which is then electromagnetically converted to electrical energy. Temperature fluctuations in a yarn muscle, having a maximum hot-to- cold temperature difference of about 13 ⁰C, were used to spin a magnetic rotor to a peak torsional rotation speed of 3,000 rpm. The electromagnetic energy generator converted the torsional energy to electrical energy, thereby producing an oscillating output voltage of up to 0.81 V and peak power of 4 W/kg, based on SMPU mass.enCC BY 4.0 (Attribution)©2018 The Authorshttp://creativecommons.org/licenses/by/4.0/NanotubesMuscles--ArtificialNanofibersPower resourcesGeothermal resourcesarticleKim, Shi Hyeong, Hyeon Jun Sim, Jae Sang Hyeon, Dongseok Suh, et al. 2018. "Harvesting electrical energy from torsional thermal actuation driven by natural convection." Scientific Reports 8(1): art. 8712, doi:10.1038/s41598-018-26983-481