Subsequently, the raw silicon must be refined. In order to manufacture one kilogram of solar silicon, up to 120 kWh of electrical energy are necessary and some 75 kilograms of carbon dioxide are generated in the process. The company JPM Silicon GmbH of Braunschweig, in cooperation with the Institute for Thermodynamics of the Technical University of Braunschweig GmbH and the company Fricke and Mallah Microwave Technology GmbH of Peine are currently developing an energy-efficient method of producing high-quality silicon using a new type of microwave system.
In this microwave oven the reaction mixture, consisting of quartz and carbon, is carefully heated to the reaction temperature. By concentration of the microwave field output in the reaction mixture, 90 per cent of the applied energy is converted, resulting in shorter heating periods and production time than in conventional electric arc furnaces. This limits the energy requirement for creating silicon and simultaneously reduces the diffusion of impurities in the reaction mixture.
Thus the silicon produced in the microwave oven has, at 99.99 %, a higher purity than raw silicon from the electric arc furnace (98 %), and can be refined into solar silicon at a reduced total expenditure – which means further energy savings. Additional research is now underway to establish the lower temperature limit for the production of silicon in microwave ovens, and thus make the process even more energy-efficient.
Project Operation:
Technische Universität Braunschweig
Institut für Thermodynamik
Hans-Sommer-Straße 5
38106 Braunschweig
Telefon 0531|391-2627
ift@tu-bs.de
www.ift-bs.de
Cooperation Partner:
JPM Silicon GmbH, Braunschweig
info@jpmsilicon.de
www.jpmsilicon.de
Fricke und Mallah Microwave
Technology GmbH, Peine
info@microwaveheating.net
www.microwaveheating.net
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