Solid oxide fuel cells introduced

Initial systems will be less than 20 MW, with typical system sizes of 1 to 10 MW. Future systems, in the megawatt class size, will boost efficiency even further by combining two solid oxide fuel cell modules with more advanced gas turbines and introducing sophisticated cooling and heating procedures. 

The book is divided into two parts. Part One introduces the reader to solid oxide fuel cells, the related main thermodynamic principles, and the main equations to be used for modeling purposes. 

Solid oxide fuel cells (SOFQ are promising electrochemical energy conversion systems to produce power for portable, mobile, and stationary apphcations ranging from several W to MW. The advantage that SOFCs have over other fuel cell systems is their direct operation on hydrocarbons and air (without being restricted to a hydrogen distribution net). Operation principle, temperature regime, and materials were introduced and are detailed in further articles. 

Oxides form the most common and interesting compounds with perovskite structure. Almost all the metallic natural elements in the periodic table are found in stable perovskites. Also, materials with this structure can be obtained by partial substitution of one or more metallic elements in the A site and/or in the B site. The wide range of properties shown by perovskite-type oxides find applications in catalysis, magnetism, solid oxide fuel cells, and superconductivity. Proper combination or partial substitution of the A site and/or B site atoms introduces abnormal valences or lattice defects, which in turn gives rise to interesting changes in their properties. 

Some perovskite-type oxides show protonic conduction and are useful for hydrogen-related electrochemical devices, including application to solid oxide fuel cells (SOFCs). Iwahara et al. reported protonic conductivity of strontium-cerate-based perovskite-type oxides in 1981 [1], Since that time, various perovskite-type proton-conducting oxides have been found. For use of the proton-conducting perovskite oxides, we should understand not only their merits but also their weak points. This chapter concerns the protonconducting properties of typical cerium- and zirconium-containing perovskite oxides from the points of view of conductivity, stability, electrode affinity, and dopant effect. Mixed conduction occurring in a special composition of the perovskite oxide is also introduced. 

Chapters I to III introduce the reader to the general problems of fuel cells. The nature and role of the electrode material which acts as a solid electrocatalyst for a specific reaction is considered in chapters IV to VI. Mechanisms of the anodic oxidation of different fuels and of the reduction of molecular oxygen are discussed in chapters VII to XII for the low-temperature fuel cells and the strong influence of chemisorhed species or oxide layers on the electrode reaction is outlined. Processes in molten carbonate fuel cells and solid electrolyte fuel cells are covered in chapters XIII and XIV. The important properties of porous electrodes and structures and models used in the mathematical analysis of the operation of these electrodes are discussed in chapters XV and XVI. 

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