A High-Temperature Thermoelectric Generator Based on Oxides

authored by: Armin Feldhoff, Benjamin Geppert
Abstract: The thermoelectric energy conversion is described in terms of fluxes of extensive variables entropy and charge, which gives a clear meaning to the figure of merit and to the power factor. Strength and sign of coupling of entropy current and electrical current is decisive for the function of a thermoelectric generator, which was built from n-type and p-type oxide ceramics to be suitable for the high-temperature range. For n-type and p-type legs, Zn0.98Al0.02O and Ca3Co4O9-derived ceramics, respectively, were used. Microstructure of both materials was investigated to some detail by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy including elemental analysis. N-type Zn0.98Al0.02O shows sub-micrometre precipitates of ZnAl2O4 spinel. P-type Ca3Co4O9-derived ceramic is a multi-phase composite as the starting powder decomposed partly during sintering. The thermoelectric materials show different temperature slopes of the power factor with the p-type material reaching 1.8 mW cm-1 K-2 at 1,000 K and the n-type reaching 1.6 mW cm-1 K-2 at 1,050 K. For the 10-leg thermoelectric generator, a figure of merit of zT = 0.10 was estimated at maximum electrical power output when the hot side was at 1,023 K, and a temperature difference of 200 K was applied.
Organisation(s): Institute of Physical Chemistry and Electrochemistry
Type: Article
Journal: Energy Harvesting and Systems
Volume: 1
Pages: 69-78
No. of pages: 10
ISSN: 2329-8774
Publication date: 01.06.2014
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Renewable Energy, Sustainability and the Environment, Energy Engineering and Power Technology, Electrical and Electronic Engineering, Electrochemistry
Sustainable Development Goals: SDG 7 - Affordable and Clean Energy
Electronic version(s): https://doi.org/10.1515/ehs-2014-0003 (Access: Open)
https://doi.org/10.1515/ehs-2014-0016 (Access: Open)
https://doi.org/10.1515/ehs-2014-0016 (Access: Open)