Thermoelectric Energy Harvesting System Based on Water-Stored Energy and Daily Ambient Temperature Variations

This paper presents the development of a low-power electronic system powered by a thermoelectric generator, based on Peltier cells, which takes advantage of daily temperature variations in the environment using a tank with 6 liters of water as a thermal accumulator. The generator works both day and night, since it uses a dc-dc boost converter with bipolar input. The system avoids using batteries because it charges a 0.1 F supercapacitor module between 2.40 and 3.15 V, so the useful energy in each charging cycle is 208 mJ. This energy is sufficient so that the system can measure the ambient temperature, represent it on a display and record it along with the date and time on a memory card when there is enough stored energy. The PSpice model and the simulation of the generator is also presented and experimental results of its operation are presented for two days. It is derived that in that period, with a maximum temperature difference of 10 °C, the system is able to charge the supercapacitor thirteen times per day, which means a daily useful energy of 2.7 J. Finally, results of the autonomous system performance for four days are presented.