This project will explore a novel class of ‘n’ type thermoelectric oxides that are stable at high temperature in the coal-fired flue gas environment. It will focus on thermoelectric oxides with high figures of merit, employing the recent observation in the literature that thermoelectric figure of merit increases rapidly in the vicinity of the Curie temperature for ferroelectric materials (thermoelectric-ferroelectric coupling).
The Department of Energy (DOE) National Energy Technology Laboratory (NETL) sponsors the University Coal Research (UCR) Program to further the understanding of coal utilization. Since the program’s inception in 1979, its primary objectives have been to (1) improve understanding of the chemical and physical processes involved in the conversion and utilization of coal in an environmentally acceptable manner; (2) maintain and upgrade the coal research capabilities and facilities of U.S. colleges and universities; and (3) support the education of students in the area of coal science.
Waste heat recovery is an attractive approach to increase the efficiency of, and reduce emissions from, power plants and industrial processes. One effective strategy to recover waste heat is the use of thermoelectric power modules that generate electric power under temperature gradients. In order to develop this approach for wide scale applications (e.g., coal-fired power plants or industrial plants), the thermoelectric module must be efficient, inexpensive, and stable in the operating environment (high temperature, corrosive gases). The current generation of thermoelectric materials, intermetallics such as bismuth telluride (Bi2Te3) are expensive and unstable at high temperature in an oxidizing As part of the UCR Program, NETL has partnered with the University of Washington in a project that will engineer high-temperature thermoelectric oxides at multiple length scales that can be used for energy harvesting.
This project’s success will pave the way for the development of efficient high-temperature, stable thermoelectric modules for waste heat recovery from coal-fired power plants and other industrial systems where process heat is an important byproduct (e.g., steel plants), resulting in higher efficiencies and reduced pollution and greenhouse gases. Another important outcome of this research is the training and education of a PhD student who will work on the scientific issues outlined in the research and will also be exposed to the broader context of research in this important area of energy efficiency and security.
Goals and Objectives
The overall goal of this project is to develop ‘n’ type thermoelectric oxide materials and microstructures with high figures of merit. These, together with the already well established ‘p’ type thermoelectric oxides with high figures of merit (e.g., Na0.5CoO2), can be used to make highly efficient thermoelectric devices for waste heat recovery in coal-fired power and industrial plants.
The specific objectives of the proposed research are (1) to use combinatorial materials exploration to rapidly screen a broad composition range in order to identify the most promising compositions of ferroelectric materials with high Curie temperatures; (2) to investigate the thermoelectric properties of the most promising ‘n’ type thermoelectric oxides in these families; (3) to develop processing approaches to make oriented crystalline oxides (in order to exploit the expected anisotropic nature of the materials); and (4) to develop processing approaches to make hierarchical anisotropic porous structures in order to evaluate the effect of micro- and macro-pores on thermoelectric properties.
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