This book provides an overview of leading alternate energy sources and technologies. It addresses renewable sources, including solar energy (solar thermal and solar photovoltaic), wind energy, biomass energy, geothermal energy, ocean energy and small hydropower, as well as nonrenewable sources, including chemical energy (batteries, hydrogen energy and fuel cells), nuclear energy, magnetohydrodynamics, thermoelectricity, thermionics, alkali metal thermal electric conversion, and energy storage. The book primarily intended to support courses for undergraduate studies in science and engineering. It is also intended for wider use beyond colleges and universities for general training and as a reference on the subject. Therefore, the book deliberately contains more material than could be covered in one specialist course.