Energy can also be stored in the form of an electrostatic field. Let us consider an electrical capacitor, that is, a device that can collect electric charge which is establishing an electric field and hence storing energy. The capacitance C of a capacitor is defmed by the amount of charge q it can take up and store per unit of voltage. The properties of this medium may be described by the constant k called the permittivity, which is measured in F/m since both A and d have metres as the basic unit. The electric field E is homogeneous inside the plate capacitor only when the distance between the plates is small. In order to keep the charges at the plates divided, and thereby to maintain the electrostatic fi eld, the dielectric medium must have a low electronic conductivity; so we are looking for dielectric materials with high permittivity.

Chapter Contents:

• 10.1 Theoretical background
• 10.2 Capacitor storage media
• 10.2.1 Supercapacitors
• 10.3 Power extraction

Inspec keywords: dielectric materials; capacitor storage

Other keywords: capacitor bank storage; dielectric materials; electronic conductivity; electric charge; plate capacitor; electrical capacitor; electrostatic field

Subjects: Storage in electrical energy; Dielectric materials and properties; Other energy storage