SOFC Stack and System Development at Forschungszentrum Jülich

Abstract

Long-term stable and robust stack technology is a pre-requisite for a successful implementation of SOFC in the market and so it is one of the main issues in SOFC development. Also bigger stacks are desirable for systems with increased power output. Progress in stack and systems development is illustrated. Enhanced thermo-mechanical robustness of stacks in the kW range was demonstrated by successfully cycling a five layer stack incorporating cells of 20 × 20 cm 2 100 times between 200 and 700 • C. Aiming at the utilization of anode-supported cells from other manufacturers, the design was modified to a window frame layout, integrating in this case four 10 × 10 cm 2 cells in one layer. A 20 kW system was operated for about 7000 hours in total, thereby demonstrating the suitability of the module and system concept. As special highlights, long-term tests with short stacks have now reached operation times of 66,500 h and 34,500 h, respectively. As a relatively new subject, activities entailed by high temperature electrolysis are briefly outlined.

Electrochemical Performance and Preliminary Post-Mortem Analysis of a Solid Oxide Cell Stack with 20,000 h of Operation

“…[6][7][8][9] Recently, a short stack achieved a 10 years lifetime, and remains in operation. 10 With proper protective coating, a voltage degradation rate of less than 0.3%/kh and lifetime of more than 40,000 h at 700…”

Anode‐Supported Solid Oxide Fuel Cell Achieves 70 000 Hours of Continuous Operation

“…However, their high operating temperatures have imposed av ariety of practical limitations,a nd therefore am ajor focus of SOFC research in recent years has been new materials and optimized microstructures with properties that enable operation at lower temperatures. [10] Thea dvanced, application-orientated design developed to maturity at the Forschungszentrum Jülich makes use of electrolytesa nd anodes,e ach with at hickness on the order of 10 mm, which are mechanically supportedb yathick anode substrate.T his allowsf or ad ecrease in the operation temperature to ar ange of 600-800 8C, [11] which in turn enables the use of low-cost interconnect materials andr enders the respective material requirements for plant components less stringent.S ignificantr ecent SOFC research efforts have focused on new materials,w ith particular emphasis on cathodes and electrolytes with enhanced propertiest hat permit operation at even lower temperatures.Nevertheless,o peration at at emperature of approximately 700 8Cs till places fairly high chemical and thermo-mechanical demands on the component materials,a nd this critically affects the long-term reliability and rate of degradation of SOFC systems. [7] This configurationm ay therefore offer the best prospects for the developmento fs table and robusts tack technology with long-term reliability-prerequisites for the successful commercialization of SOFCsa nd the pre-eminenti ssue in SOFC research and development.…”

Anode‐Supported Planar Solid Oxide Fuel Cells Based on Double‐sided Cathodes

“…In addition, SOFC allows a low‐cost capture of CO 2 and high‐efficiency production of hydrogen, which makes it more attractive towards creating a futuristic carbon neutral hydrogen society . In an SOFC stack, single cells are connected in series to increase voltage output or in parallel to raise the current . A higher power provided by an SOFC stack results in greater heat dissipation during the system operation, leading to an increase in the local temperature within the stack .…”