Analysis of solid oxide fuel cell system concepts with anode recycling Roland Peters a, *, Robert Deja a , Ludger Blum a , Jari Pennanen b , Jari Kiviaho b , Tuomas Hakala c a Forschungszentrum Ju ¨ lich GmbH, Wilhelm-Johnen-Straße, 52425 Ju ¨ lich, Germany b VTT, Technical Research Centre of Finland, Biologinkuja 5, FIN-02044 Espoo, Finland c Wa ¨ rtsila ¨ Finland Oy, Tekniikantie 12, FIN-02150 Espoo, Finland article info Article history: Received 26 October 2012 Received in revised form 1 March 2013 Accepted 21 March 2013 Available online 19 April 2013 Keywords: Fuel cells SOFC systems Anode recycling Efficiencies abstract The main drivers for anode recirculation are the increased fuel efficiency and the inde- pendence of the external water supply for the fuel pre-reforming process. Different sys- tem flow-schemes have been defined and a set of parameters have been elaborated as basis for various calculations. Taking into account the combinations of layout, cell type, fuel utilization, fuel, and recycling ratio the total number of cases modeled was about 220. All calculated SOFC systems are on a high level of electrical net efficiency in the range of 50e66%. The electrical and thermal efficiencies are mainly influenced by the fuel utili- zation. The layout itself, the choice of fuel gas or the type of cell have minor effects on the system efficiency. Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction A research consortium is formed for Development of Anode Sub-System for small-scale and large-scale SOFC systems. The consortium comprises several European companies: VTT Technical Research Centre of Finland, HTceramix SA, EBZ Entwicklungs- und Vertriebsgesellschaft Brennstoffzelle mbH, Wa ¨ rtsila ¨ Finland Oy, Hexis AG and Forschungszentrum Ju ¨ lich GmbH. The high temperature fuel cell technologies have potential for high electrical efficiency up to 60% [1], and for total effi- ciency higher than 90% [2,3] based on the lower heating value. SOFC has the added benefit of offering commercial applications from 1 kW residential to several MW stationary units with high fuel flexibility. Whilst much effort is devoted to cell and stack issues, less attention has been paid to the components and sub-systems required for an operational system. The consortium is focused on the development of fuel and water management for SOFC systems. The fuel management, and especially recirculation, is a key question in achieving high electrical efficiency and rejecting external water supply. The recirculation increases the fuel utilization rate and can provide the water needed for the reforming of fuels [4]. 2. Scientific approach SOFC applications are working in a wide range of power. Small-scale SOFC systems are often addressed to electrical power of 1e5 kW. Currently a lot of development activities are carried out at this power level [1e3,5,6]. For Large-scale SOFC * Corresponding author. Tel.: þ49 2461 614664; fax: þ49 2461 616695. E-mail address: ro.peters@fz-juelich.de (Ro. Peters). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 38 (2013) 6809 e6820 0360-3199/$ e see front matter Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2013.03.110