Progress in HEXIS’ SOFC Development

Abstract

HEXIS is developing and manufacturing SOFC-based micro-CHP systems for houses and / or small companies. In the last years, we have been developing the new generation (Leonardo) of the Viessmann/HEXIS SOFC system and have them running now in field and lab tests. Additionally, the development of the next system (da Vinci) generation was kicked off and first results on prototype level achieved.This paper will report the newest results of short-stack tests and of system tests based on the new system combined with historical data of the earlier Galileo systems. These include tests running for more than 40’000 h. Moreover, results of the next system generation, reaching electrical efficiencies by steam-reforming with 50 % AC, net and total efficiencies of 95 % (LHV) will be shown.Finally, long-term and cyclic testing of systems in lab tests as well as results on robustness and performance in the field will be discussed:Degradation rates as low as approx. 0.3 % / kh, i.e. 12 mΩ cm² / kh could be shown on short-stack level successfully over 40’000 h. These stacks have been analysed with electrochemical impedance spectroscopy (EIS) in regular intervals, which will enable valuable insights in understanding fundamental degradation mechanisms in long term operation of SOFC stacks. The paper will link these results with corresponding observations on full scale stack and button cells level.