Existing energy storage systems are mainly divided into five categories: mechanical energy storage, electrical energy storage, electrochemical energy storage, thermal energy storage and chemical energy storage.
Note that other categorizations of energy storage types have also been used such as electrical energy storage vs thermal energy storage, and chemical vs mechanical energy storage types, including pumped hydro, flywheel and compressed air energy storage. Fig. 10. A classification of energy storage types. 3. Applications of energy storage
Chemical energy storage systems are sometimes classified according to the energy they consume, e.g., as electrochemical energy storage when they consume electrical energy, and as thermochemical energy storage when they consume thermal energy.
It was classified into three types, such as sensible heat, latent heat and thermochemical heat storage system (absorption and adsorption system) (65). (Figure 14) shows the schematic representation of each thermal energy storage systems (66). Figure 14. Schematic representation of types of thermal energy storage system. Adapted from reference (66).
For example, some reviews focus only on energy storage types for a given application such as those for utility applications. Other reviews focus only on electrical energy storage systems without reporting thermal energy storage types or hydrogen energy systems and vice versa.
Electrochemical energy storage system undergoes chemical process to store and produce electricity. Batteries are the most widely used electrochemical energy storage systems in industrial and household applications (28). They are classified into two types namely primary and secondary batteries.
What type of energy storage system stores electrical energy?
Electrostatic and electromagnetic energy storage systems store electrical energy, with no conversion to other forms of energy (i.e., stores as electric field). Capacitors, Supercapacitors and Superconducting magnetic Energy Storage (SMES) belong to this type of energy storage system (32).