Energy harvesting from ambient heat sources using thermoelectric generator – A modelling study

Abstract

Thermoelectric technology is an attractive energy harvesting technique for direct conversion of heat into electricity from ambient heat sources. This can provide sustainable energy to small and self-powered devices for Internet-of-Things, wearable electronics, and sensors in remote areas. Currently, bismuth telluride and magnesium bismuthide based thermoelectric devices are used for ambient condition applications. Transparent thermoelectric materials offer opportunities to design multifunctional devices for energy harvesting, cooling, optoelectronics, and sensor applications. Energy conversion efficiency of a thermoelectric generator (TEG) is dependent on thermoelectric materials properties and geometrical design of p-n module. Seebeck coefficient, electrical conductivity and thermal conductivity is optimized to obtain high figure-of-merit (ZT) to ensure high performance of TEG. Geometrical design parameters such as thermoelectric leg length, cross-section area, load resistance play import roles on efficient heat transfer across the heat source and sink in a p-n module for maximum power output of a TEG. We report power output calculated using analytical modelling for a state-of-the-art transparent indium-tin-oxide and copper iodide thermoelectric module. The maximum power output was calculated to be 9.9 µW at ΔT = 20 K for a 5 µm leg length and 500 µm2 cross section area. Large-area application of TEGs should optimize the inherent thermoelectric materials’ parameters and geometrical design to maximize the power output in the range of mW - µW. Energy harvesting from ambient heat sources using efficient TEGs can be used for energy harvesting applications from building’s glass windows, wearable technologies, geothermal fields, and low-grade waste heat from industrial applications.