The book will cover energy storage systems, bioenergy and hydrogen economy, grid integration of the renewable energy systems, distributed generation, economic analysis and environmental impacts of renewable energy systems. Core issues to be discussed include: mechanical, electrical and thermal energy storage systems, batteries, fuel cells, biomass and biofuels, hydrogen economy, distributed generation, a brief presentation of microgrids, and in depth discussions of economic analysis and methods of renewable energy systems, environmental impacts, life cycle analysis, and energy conservation issues. Readers will be encouraged to solve the problems and questions, which are useful way to understand and apply he concepts, and the topics included.