Thermoelectric materials enable energy generation from waste heat

June 22, 2020 // By Christoph Hammerschmidt
Thermoelectric materials enable energy generation from waste heat
Thermoelectric generators based on the Seebeck effect generate economically usable electrical voltages simply by a temperature gradient. Vacuumschmelze GmbH, an expert in magnetic materials, can now produce the required materials on a large scale.

In industry, traffic and households, a huge amount of unused energy is generated in the form of waste heat - in Germany alone, this amounts to approximately 300 terawatt hours per year (TWh/a). This potential could be used as a sustainable energy resource by means of thermoelectric generators (TEG). In this case, the thermal energy is converted directly into electrical power. This makes an important contribution to energy recovery and thus to reducing CO2 emissions. The thermoelectric materials Vacotherm n and Vacotherm p are used in such thermoelectric generators.

Vacotherm are hafnium-free intermetallic half-Heusler compounds. Both semi-conducting thermoelectric material types fit together perfectly in their coefficients of thermal expansion. They are stable at high temperatures and are characterized by high mechanical strength. The key parameter for the conversion capacity in thermoelectric materials - the ZT quality index - shows extraordinarily high values of 0.9 at 500 °C for both types. 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 for 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 plants are robust, compact and maintenance-free.

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