ABSTRACT
This chapter presents important elements, tools, and methods for a quantitative and qualitative comparison of energy storage means. Through their energy capacity, but also their power capability, different solutions can be analyzed and designed for a given application. The definitions and symbols for energy density and power density are given, related to the volume and to the weight of a given system or component.
The chapter presents a very important but less-known theory called “the theory of Ragone Plots,” which makes it possible to evaluate the real amount of energy that can be extracted out of a given system, depending on the level of power chosen for the discharge process. For the reverse process, the required amount of energy for charging also depends on the level of power. The theory of Ragone plots is completed by a similar tool called “the modified Ragone representation.”
The chapter comprises two exercises related to the theory of Ragone plots. The first illustrates the differences of the efficiency between normal and fast charge of an electrical vehicle. For the two cases, power electronic converters are described, and their limited influence on global efficiency is demonstrated. The second exercise concerns the choice and design of a storage device for the KERS (kinetic energy recovery system) of a race car.
