Intermediate temperature solid oxide fuel cells

High temperature solidoxidefuelcells(SOFCs), typified by developers such as Siemens Westinghouse and Rolls-Royce, operate in the temperature region of 8501000 C. For such systems, very high efficiencies can be achieved from integration with gas turbines for large-scale stationary applications. However, high temperature operation means that the components of the stack need to be predominantly ceramic and high temperature metal alloys are needed for many balance-of-plant components. For smaller scale applications, where integration with a heat engine is not appropriate, there is a trend to move to lower temperatures of operation, into the so-called intermediate temperature (IT) range of 500750 C. This expands the choice of materials and stack geometries that can be used, offering reduced system cost and, in principle, reducing the corrosion rate of stack and system components.

This review introduces the IT-SOFC and explains the advantages of operation in this temperature regime. The main advances made in materials chemistry that have made IT operation possible are described and some of the engineering issues and the new opportunities that reduced temperature operation affords are discussed.

Thistutorial reviewexamines the advances being made in materials and engineering that are allowing solidoxidefuelcellsto operate at lower temperature. The challenges and advantages of operating in the so-called intermediate temperature range of 500750 C are discussed and the opportunities for applications not traditionally associated with solidoxidefuelcellsare highlighted. This article serves as an introduction for scientists and engineers interested in intermediate temperature solidoxidefuelcellsand the challenges and opportunities of reduced temperature operation.