State-of-the-art review of energy harvesting applications by using thermoelectric generators

Global energy demand is increasing day by day and this has led to the discovery of developed technologies to produce the required energy. Heat is a very common source to generate electric energy however the efficiency of equipment using heat as an energy generation source is limited, and it creates huge amounts of heat energy as waste. One of the technologies which has attracted significant attention in the last two decades is thermoelectric generators (TEGs) that can generate electricity from waste heat. After quick research, it is obvious that different active and passive devices can be manufactured not only for big size energy generators but also for the small size and wearable generators which use heat in order to create electric energy via TEGs. In this review, promising results gathered from different applications of TEGs in different industries claimed as well as the basic principles of thermoelectricity and fundamentals of energy harvesting process from temperature gradient. Experiments on TEGs were done by many researchers as well as analytical models through the years, and validated that TEGs are useful for the energy generation. This work points out the relationship between heat sources and thermoelectric modules (TEMs) and can represent beneficial information for the optimization and application of TEGs.