Heat storage thermoelectric generator as an electrical power source for wireless Iot sensing systems

Abstract

This article demonstrates a new approach using a thermoelectric generator (TEG), which converts thermal energy from ambient temperature fluctuations into electricity for the power source of portable devices. Using TEGs with heat storage material on one side of the TEG, a temperature difference can be created at both sides of the TEG from ambient temperature variations. In this work, the electric power generation and its storage to a capacitor are evaluated for the TEG-heat storage device. Two kinds of TEGs (#1 and #2) with different sizes have been evaluated. Maximum output power densities of TEGs #1 and #2 are 0.27 and 0.45 mW/cm2 at temperature difference ∆T = 7°C, respectively. The electric power from the TEG can be stored in a capacitor via a DC-DC converter. The temperature difference dependences of the electronic conversion efficiency for the DC-DC booster are evaluated for both TEGs. A charge stored in the capacitor is 113 μAh under ∆T = 3°C. The maximum output power and the storable energy in the capacitor are 30 μW and 500 mJ, respectively, under ambient temperature fluctuations in near room temperature. The investigation in this work could possibly lead to high potential for battery-free wireless sensing systems.