Usability of Bismuth Telluride as Material for Thermoelectric Generators in Heavy-Duty Vehicles

Abstract

Around 98% of heavy-duty vehicles still use internal combustion engines to cover long-haul freight traffic in the future. The engines convert around one third of the fuel’s energy into power while two thirds are lost through heat. Thermoelectric Generators offer an interesting opportunity to convert a part of this heat into electricity. This relieves the alternator and improves the vehicle’s efficiency by around 3%. However, most of the available Thermoelectric Modules use Bismuth Telluride (BiTe) as active material, which is often limited by the hot side temperature of up to 250°C. In this paper two BiTe modules which are made for high temperatures of up to 330°C are analysed. The modules are from the distributers TEGpro and thermalforce. They are characterized as a component with the so-called reference method, which provides application-related properties. The results show that the output power is similar to the values given in the datasheet of the modules, but the measured efficiency is significantly lower. This means a higher heat flux is needed to provide the same power. The measured values are analytically compared to typical exhaust gas temperatures of diesel and modern gas engines of heavy duty vehicles. The potential power for a Thermoelectric Generator is estimated and the conclusion is that BiTe might be applicable for diesel, but not for gas engines. Therefore new high temperature and low-cost modules, which are in development, are needed for future applications.