*Review* **Sustainability and Circular Economy Perspectives of Materials for Thermoelectric Modules**

**Manuela Castañeda <sup>1</sup> , Elkin I. Gutiérrez-Velásquez <sup>1</sup> , Claudio E. Aguilar <sup>2</sup> , Sergio Neves Monteiro <sup>3</sup> , Andrés A. Amell <sup>4</sup> and Henry A. Colorado 1,\***


**Abstract:** The growing demand for energy and the environmental problems derived from this problem are arousing interest throughout the world in the development of clean and efficient alternative energy sources, which involve ecological processes and materials. The materials used in the processes associated with thermoelectric generation technology will provide solutions to this situation. Materials related to energy make it possible to generate energy from waste heat residues, which are derived from various industrial processes in which significant fractions of residual energy are deposited into the environment. However, despite the fact that thermoelectric technology represents some relative advantages in relation to other energy generation processes, it in turn faces some technical limitations such as its low efficiency with respect to the high costs that its implementation demands today, and this has been the subject of intense research in recent years. On the other hand, the sustainability of the processes when analyzed from a circular economy perspective must be taken into account for the implementation of this technology, particularly when considering its large-scale implementation. In this article, a systematic search focused on the sustainability of thermoelectric modules is carried out as a step towards a circular economy model. The review aims to examine recent developments and trends in the development of thermoelectric systems in order to promote initiatives in favor of the environment. The aim of this study is to present a current overview, including trends and limitations, in research related to thermoelectric materials. As a result of this analysis, it was found that aspects related to costs and initiatives related to circular economy models have been little explored, which represents not only an opportunity for the development of new approaches in the conception of thermoelectric systems, but also for the conception of optimized designs that address the current limitations of this technology.

**Keywords:** thermoelectric modules; cost-efficiency ratio; sustainability; life cycle; circular economy
