In late 2004, the pilot Solzinc solar reactor was commissioned. The European Union and the Swiss Federal Office of Science and Education are funding this project to demonstrate the technical feasibility and the economical potential of producing Zn by reducing zinc oxide with the aid of concentrated solar energy and a small amount of carbon at a close to industrial scale. The zinc can be used as a means to store solar energy in a chemical way, e.g. suited to release electricity in Zinc-air fuel cells. This allows on demand use, boosting the availability of solar energy. Furthermore, as the Zinc-air fuel cells’ waste is ZnO, we get a cyclic process by reducing this ZnO in the Solzinc solar reactor. Numerous lab tests and numerical studies of the chemical and thermal behavior of the solar carbothermic ZnO reduction process were conducted by the Swiss Paul Scherrer Institute, the Swiss Federal Institute of Technology, the Israeli Weizmann Institute and the French CNRS Processes, Materials and Solar Energy laboratory. An indirectly heated beam-down reactor concept was chosen and influencing parameters, such as the type of carbon, the stoichiometry of the ZnO-C mix and the process temperature were explored. Based on these findings the technology was scaled up for the pilot plant for about 0.25 MW solar input leading to a designed zinc production rate of 50kg/h. The Swedish company ScanArc Plasma Systems AB developed a special quench system to produce zinc dust directly from the gaseous zinc exhausted from the solar reactor. The dust’s characteristics were adapted to the requirements of the Zn-air fuel cells developed by the German company ZOXY Energy System AG. The resulting zinc can be easily stored and transported for generating electricity as needed. In 2004, the pilot reactor, the quench system and extensive instrumentation were installed at the Weizmann Institute’s solar facilities to process batches of up to 500 kg of ZnO-C mixture. After cold testing of the installation and fulfilling all safety requirements, the first batches were processed. This paper explores the results of the commissioning to show the technical feasibility of this process to produce zinc and to store solar energy.

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