In industry, transport and households a huge amount of unused energy is generated in the form of waste heat. This potential could be used as a sustainable energy resource using thermoelectric generators (TEG). The thermal energy could be converted directly into electrical power, which makes an important contribution to energy recovery and thus to reducing of CO2 emissions. The thermoelectric materials VACOTHERM n and VACOTHERM p are used in such powerful thermoelectric generators. The working mechanism is based on the Seebeck-effect: the materials generate a usable electrical voltage when placed in a temperature gradient.
VACOTHERM® are hafnium-free intermetallic half-Heusler compounds. Both semiconducting thermoelectric material types match perfectly in terms of thermal expansion coefficients. They are stable at high temperatures and are characterized by high mechanical strength. The key parameter for the ability of conversion in thermoelectric materials, the figure of merit ZT, shows for both types extraordinarily high values of 0.9 at 500 °C. VACOTHERM is tailored to achieve optimum efficiency at higher temperatures where conventional thermoelectric materials made of bismuth telluride fail. This makes them ideal candidates for a wide range of heat recovery applications.
They are used in the recovery of exhaust gas energy in motor vehicles, as well as in waste heat recovery in industrial applications or to improve efficiency in combined heat and power plants. The main advantages of this direct energy conversion are that no mechanical or chemical processes and no moving parts, liquids or gases are required. The units are robust, compact, and maintenance-free.
“With our recently developed hafnium-free VACOTHERM thermoelectric materials we are now able to produce these materials in a large scale making their use in application fields with fluctuating waste heat and high annual operation hours economical,” says Ute Fecher-Petzold, Product Manager at VAC. “We have already implemented several pilot projects and are confident that we will be able to start series production in the short to medium term”.