Charge and Energy Storage in Electrical Double Layers presents the basic scientific concepts and implementation of procedures devised to obtain capacitive energy from changes in the potential of electrical double layers when the salinity of solutions is changed. Capacitive deionization-- the closely connected reciprocal process--is also considered. The book covers the fundamentals of electrical double layers and ions transport in porous media, the description of promising techniques of energy extraction, and the practical problems involved in each. It is written for scientists in academia and industry, and for graduate students working in supercapacitors, capacitive mixing and deionization.