Sunfire commercially distributes products for various markets (SOFC, SOEC and Co-SOEC) with its stack and system technology. To achieve an ideal tradeoff between cost, performance, and degradation for its customers, Sunfire’s stack design is continuously being improved. In this publication, latest results that resulted in a decrease of the combined life cycle costs (€ kW-1 h-1) of approx. 40% and cost projections for large scale production will be presented. Furthermore, recent changes in automation and industrial scale-up that lead to a current annual production volume of >10MW and next steps to further increase this value will be shown. Last but not least, updates on the recent development for Sunfire’s products Home, Remote and Hylink/Synlink will be given.

In the past years, sunfire has increased its product portfolio and production depth. Four product classes (single stacks and stack modules for SOFC and SOEC) are tackling several markets (offgrid, on-grid, mobile). A ceramic center and a new production facility were inaugurated. The R&D activities are strongly driven by market requirements. With the new SOC stack electrolysis operation is introduced aside fuel cell operation. Furthermore, an increase in power density and a reduction of cost was achieved under the constraint of using standard industrial materials. Latest results of SOC single stack testing like I-V curves and reversible operation will be presented. The engineering and testing of stack modules in the power range >25 kW will be also shown. Company PortraitStarting to produce fuel cell stacks by 2006, sunfire established a vast experience of the SOFC technology. Besides the continuous economic growth, the last years led to a focus shift onto a new field of application, combining SOFC and SOEC into a universal -so called SOC stack which is capable of both transforming chemical energy into electrical energy and vice versa. Market demand shows, that besides the "classic" SOFC fields of application like remote and mobile power generation e.g. in automotive, ships or at pipeline control stations, the SOC addresses the need for electricity storage and fluctuation buffering which came up with the fast rise of sustainable energy production in industrial countries. Acting as an electrolyser when there is an oversupply of wind-or solar power, the SOC turns electrical energy into chemically bound energy in the form of H 2 , which can be stored in almost unlimited amounts. In the moment the electricity demand exceeds the supply, SOC is turned from electrolyser to fuel cell mode and converts the gas bound energy back to electricity. Recently there are plenty of requests of multinational companies that want to include SOC products into their portfolio. Hereby, sunfire can act as a vendor of stacks, stack modules with already integrated gas supply or whole systems in the power range of one to several hundred kW. Recently, a company-owned pilot plant for a power-to-liquid process is put into operation. With the use of SOEC technology, the plant produces liquid fuels and other valuable products like highly purified and customized waxes for chemical industry.Besides the focus on R&D in both stack and integration topics, the development and optimization of production processes play a role with increasing importance for the company. As the stack production will exceed the number of 1000 stacks/a. in 2015, there is a tremendous potential for production automation, which will subsequently lead to 10.1149/06801.0125ecst ©The Electrochemical Society ECS Transactions, 68 (1) 125-129 (2015) 125 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 155.69.4.4 Downloaded on 2015-08-23 to IP

The mechanical reliability of reversible solid oxide cell (SOC) components is critical for the development of highly efficient, durable, and commercially competitive devices. In particular, the mechanical integrity of the ceramic cell, also known as membrane electrolyte assembly (MEA), is fundamental as its failure would be detrimental to the performance of the whole SOC stack. In the present work, the mechanical robustness of an electrolyte-supported cell was determined via ball-on-3-balls flexural strength measurements. The main focus was to investigate the effect of the manufacturing process (i.e., layer by layer deposition and their co-sintering) on the final strength. To allow this investigation, the electrode layers were screen-printed one by one on the electrolyte support and thus sintered. Strength tests were performed after every layer deposition and the non-symmetrical layout was taken into account during mechanical testing. Obtained experimental data were evaluated with the help of Weibull statistical analysis. A loss of mechanical strength after every layer deposition was usually detected, with the final strength of the cell being significantly smaller than the initial strength of the uncoated electrolyte (σ0 ≈ 800 MPa and σ0 ≈ 1800 MPa, respectively). Fractographic analyses helped to reveal the fracture behavior changes when individual layers were deposited. It was found that the reasons behind the weakening effect can be ascribed to the presence and redistribution of residual stresses, changes in the crack initiation site, porosity of layers, and pre-crack formation in the electrode layers.

SOFC (solid oxide fuel cell) are known for a high electrical efficiency and especially the ESC (electrolyte supported cells) for a good robustness for system operation. Nevertheless common system concepts that use CPOX (catalytic partial oxidation) or SR (steam reforming) as fuel processing still show disadvantages. CPOX systems will not pass efficiencies beyond 35% and SR systems need additional water processing that increases complexity, as well as initial and operational costs. A technical solution for those disadvantages is a staged system design. staxera GmbH has developed a concept and EBZ GmbH has designed, built and operated a proof-of-concept installation including a serial connection of two SOFC stacks. This system design achieved an electrical efficiency of 55% due to a double use of fuel gas in stage two. In contrast to other highly efficient SOFC systems, mostly SR systems, no additional water supply and processing were needed.

Knowledge of the actual fuel utilization of a fuel cell stack is very important for characterizing the performance of a fuel cell stack. The actual fuel utilization in many cases does not equal the set fuel utilization defined by the electrical current and the fuel gas flow rate due to possible leakages or an inhomogeneous fuel gas distribution to the fuel cell stack layers. This manuscript describes a method for determining the actual fuel utilization of a fuel cell stack or a fuel cell layer by recording the cell voltages at different fuel utilizations.