Thermoelectric generators are a potential alternative to improve the performance of internal combustion engines. In this research, an analysis of the energy recovery capacity, fuel-saving, emission reduction, and economic analysis of a thermoelectric generator located in the exhaust system of a stationary diesel engine has been carried out. For the experimental tests, three types of fuels (D100%, BP5%, and BP10%) have been used, as well as changes in the conditions of torque (3 – 6 Nm) and rotational speed (3000 – 3800 rpm) of the engine. The results show a recovery capacity of 55.5 W, 66.5 W, and 70.6 W for fuels D100%, BP5%, and BP10%, representing recovered energy of 2.33%, 2.78%, and 2.96% compared to the output power of the engine. The use of the thermoelectric generator has allowed achieving fuel savings of 2.9%. The implementation of the TEG implies a reduction in emissions (CO2, HC, and NOx) of 1.61%, 1.82%, and 2.07% for D100%, BP5%, and BP10% fuels. Economic savings of 528 USD/kWh (36 months) have been achieved, showing the technology's potential, especially in high-power engines or regions with high fuel costs. Future studies will focus on improving the thermoelectric generator's recovery capacity.