ZnO-based thermoelectric generators as eco-friendly alternatives to alkaline batteries: Design,optimization,and life cycle analysis

Abstract

In this study, a ZnO based functionally graded thermoelectric device (FGTED) is computationally developed and optimized in a two-step approach; (i) optimization of the spatial distribution of thermoelectric properties using power law and (ii) optimization of the geometry. It is thereafter employed for development of a thermoelectric generator (TEG) to obtain enhanced voltage output comparable to a commercially available AA alkaline battery. An analytical model for determining the power output of a FGTED is also developed, demonstrating strong agreement with numerical simulations exhibiting deviation of 8.24% only. The findings reveal that the power law based thermoelectric properties distribution optimization enhanced voltage output from 3.73 × 10⁻³ V to 1.51 × 10⁻² V, representing an order of magnitude enhancement. Further, the geometric optimization reduced internal resistance in the same device from 2.5 Ω to 1.25 × 10⁻² Ω, elevating the voltage output from 1.51 × 10⁻² V to 5 × 10⁻² V, a 3.3 times improvement. The maximum voltage output obtained from the developed TEG is 2.17 V, which is comparable to that of an AA alkaline battery. Additionally, a life cycle analysis performed indicates that replacing AA alkaline batteries with the ZnO based TEG can reduce carbon emissions by 89% over a 1-year period, highlighting its potential as a sustainable alternative for low power energy applications.