The transition toward net-zero emissions requires technologies that can improve energy efficiency or recover energy from waste heat discharged into the environment. A substantial proportion of primary energy is lost as waste heat during electricity generation, combustion, transportation, and industrial processes, creating pronounced potential opportunities for energy recovery. This talk reviews the principles, development, and applications of thermoelectric generation (TEG) as a solid-state approach for converting temperature differences directly into electricity through the Seebeck effect. Compared with conventional waste-heat recovery technologies, TEGs offer several advantages, including compact construction, quiet operation, long service life, low maintenance requirements, and the absence of moving components and refrigerants. However, their wider implementation remains constrained by relatively low conversion efficiency, high material costs, and challenges in thermal management and system integration. Recent research on thermoelectric systems is discussed, with an emphasis on material selection, thermoelectric leg geometry, operating temperature, cooling channel design, segmented modules, thermal stress, and heat transfer enhancement. Experimental design, numerical analysis, evolutionary computation, and multi-objective optimization are applied to improve output power, conversion efficiency, and system reliability. Representative applications include industrial furnaces, hot springs, solar water heaters, flexible and wearable generators, methane partial oxidation reactors, and grid-connected kilowatt-scale systems. Particular attention is given to integrated energy systems that combine thermoelectric generation with biochar production. In these systems, high-temperature exhaust gas first produces electricity and is subsequently utilized for biomass pyrolysis. Although thermoelectric power alone may provide limited carbon reduction, stable carbon storage in bamboo- and coffee-ground-derived biochar can generate substantial net-negative greenhouse-gas emissions. Such cascading waste-heat utilization demonstrates a promising pathway toward circular heat management, renewable power generation, carbon sequestration, and sustainable industrial development.

Waste heat; thermoelectric generator; computational fluid dynamic; efficiency; design; optimization.