Written for the reader with an interest in the performance of energy conversion processes that involve direct methods of producing electric power from heat and other primary sources, this book examines the means available for converting heat to electricity without the intermediate generation of rotating shaft power. A physical and quantitative understanding of the limitations of a number of commercially interesting methods are developed to allow assessment of the technologies for specific applications. The list of processes considered is limited by performance measured in terms of cost, conversion, efficiency, and power density. This book is a natural adjunct to Energy Conversion (OUP, 1994), which focuses on the thermodynamics and mechanics of heat.