Energy storage and in particular electrical storage of energy has become a very talked about topic in circles ranging from lay persons in regard to hybrid and battery electric vehicles to professionals and certainly by legislators and government energy policy makers. But to even professionals the distinctions between physical and chemical forms of electric energy storage are unclear and at times poorly understood, if at all. This book takes a critical look at physical storage of electricity in the devices known collectively as electrochemical capacitors and particularly as ultracapacitors. In its 12 chapters, this text covers ultracapacitor and advanced battery topics with emphasis on clear understanding of fundamental principles, models and applications. The reader will appreciate the case studies ranging from commercial to industrial to automotive applications of not only ultracapacitors but of these power dense components in combination with energy dense battery technologies.