Energy storage and in particular electrical storage of energy has become a very talked about topics in circles, ranging from lay person in regard to hybrid and battery electric vehicles, to professional and certainly by legislators and energy policy makers in government. But even to professional the distinction 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 ultracapacitors and advances battery topics with emphasis on clear understanding of fundamental principles, models and applications. The reader will appreciates the case studies ranging from commercial to industrial to automotive applications of not only ultracapacitors but these power device components in combination with energy dense battery technologies.