This press release is available in German.
Solid oxide fuel cells (SOFCs) directly convert chemical energy into electrical energy. Although an overall efficiency above 95 per cent can be achieved at an operating temperature of nearly 900 degrees Celsius, a certain amount thereof is waste heat and can currently only be used for domestic hot water supply or heating purposes. Andre Heel, chemical engineer and research coordinator of the strategic partnership between Empa and Hexis AG, has something else in mind. He wants to "upgrade" it into electricity using thermoelectric converters (TECs). "This will not only increase the efficiency of the fuel cell system", says Heel. "Highly efficient energy conversion technologies are also the most effective way to conserve valuable resources."
Like adhesive plasters, TECs which are already commercially available are stuck to the walls of motors, industrial ovens and other heat sources. They consist of two different types of semiconducting materials on either side. If there is a temperature gradient between the two sides, electrons are transferred from one side to the other, i.e. an electric current is induced, which can be "harvested".
Under Heel's leadership, Empa kicked-off the four-year "HITTEC" project this summer (HIgh Temperature ThermoElectric Converters). Its aim is to develop and optimize materials for TECs that can withstand elevated temperatures. Not a small feat, given that current TECs can only be operated at temperatures below 300 degrees. What's more, HITTEC materials also have to combine seemingly contradicting properties. They should, for instance, be both highly electrically conductive and at the same have a poor thermal conductivity.
A team led by Anke Weidenkaff, head of Empa's Laboratory for Solid State Chemistry and Catalysis and professor of chemistry and biochemistr
|Contact: Andr Heel|
Swiss Federal Laboratories for Materials Science and Technology (EMPA)