Advances in Thermoelectric Generators Modules (TEGs): Applications, Performance, and Global Trends in Renewable Energy Systems

The integration of thermoelectric modules (TEMs) into renewable energy systems represents a critical technological frontier for global energy efficiency. This review systematically analyzes the scientific output in the field, which has experienced accelerated growth over the last decade, reaching a historical peak in publications between 2023 and 2024. Geographically, research is led by China, Iran, Turkey, and India. Regarding sectoral distribution, the analysis reveals that solar energy dominates applications, divided into solar thermal (25.53%) and photovoltaics (23.40%), followed by biomass (21.28%) and geothermal energy (17.02%), while ocean energy (12.77%) remains the least developed area. Despite the surge in scientific interest, the results confirm a significant methodological gap: 72.34% of the literature relies exclusively on pure simulations and numerical modeling, whereas only 27.66% incorporates experimental validation. This theoretical dependence translates into a lack of data regarding long-term operational reliability; consequently, mechanical analysis indicates that performance degradation becomes critical after the first 4000 cycles of operation, resulting in an 18% power loss. It is concluded that closing the gap toward commercial scale requires a transition from idealized modeling toward polygeneration schemes and thermal coupling designs that mitigate cyclic mechanical stress. This work provides a synthesis that serves as a roadmap for future engineering implementations at the energy-thermal management nexus.