Development of robust SOFC microCHP systems

As SOFC microCHP (SOFC: solid oxide fuel cell; CHP: combined heat and power) systems come closer to commercial application, Vaillant GmbH as one of Europe's largest heating appliance manufacturers and their development partner Fraunhofer IKTS focus on system development for large scale demonstration. The core of the approach is to develop a simple, robust CHP unit with a limited number of components, low maintenance requirements, ease of assembly and only gas and electricity as the principal interfaces. Even though exclusive electrical power generation might lead to higher electrical efficiencies, the object of CHP is using the excess heat of power generation for space heating and domestic hot water. By this the primary energy efficiency is significantly higher than with conventional heating technology like a gas heater especially if decentralized generation is considered, avoiding transmission losses. The focus is turned towards simple and robust processes to keep system complexity within limits. To be able to do this the reforming process needs to be simple, especially to avoid the need for water and water management within the unit. Reforming test results using partial oxidation on a component test stand are being presented. The aim was to reform all relevant different gas compositions of natural gas and derive parameters for system operation. Several prototypes are being operated under near field-test conditions in order to do experiments ranging from long-term-testing to automation development and (thermal- and redox-) cycling tests. The efforts of automation development are presented showing transient system operation like an automated system start-up and an automated load change. Current test results and prototype designs will be further explained during the presentation