# Progress in Energy Storage Technologies and Methods for Renewable Energy Systems Application
## 4 Research Classification
### Electrochemical Energy Storage System  
The industry chain of the EESS is a vast system, which is made up of an upstream, downstream, and midstream. Furthermore, the chain, in the upstream, includes a battery's raw materials, the suppliers of electronic components, and so on; midstream mainly includes the battery, BMS, PCS, EMS, and other parts suppliers; the downstream incorporates energy storage integration suppliers, energy storage system installers, and the users who rely on the power grid, namely, families, industrialists, businessmen, and wind and/or light power stations. Lithium battery energy storage system composites with PCS, EMS, electric cores, and BMS. EESS is a structure made up of batteries, PCS, BMS, EMS, and other accessories. From the cost of the EESS, batteries account for about 60%, PCS is 20%, BMS is 5%, EMS is between 5% and 10%, and another accessory is about 5%. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{2}{c}{**Energy Storage Type**} & \multicolumn{1}{c}{**Typical Power Rating**} & \multicolumn{1}{c}{**Rated Energy**} & \multicolumn{1}{c}{**Features**} \\ \hline \multirow{4}{*}{Physical Energy Storage} & \multirow{2}{*}{PHS [81]} & \multirow{2}{*}{100–2000 MW} & \multirow{2}{*}{4–10 h} & For large scale, mature technology, slow response, and need for geographic resources \\ \cline{3-3} \cline{5-5}  & & & & For large scale, slow response, need geographic resources \\ \cline{2-5}  & \multirow{2}{*}{CAES [82]} & \multirow{2}{*}{10–300 MW} & \multirow{2}{*}{1–20 h} & For large scale, slow response, need geographic resources \\ \cline{3-3} \cline{5-5}  & & Flywheel [65] & 5 kW–10 MW & 1 s–30 min & Higher power ratio, high cost, high noise \\ \hline \multirow{4}{*}{Electromagnetic Energy Storage} & \multirow{2}{*}{
\begin{tabular}{c} Superconducting Energy Storage [83] \\ \end{tabular} } & \multirow{2}{*}{10 kW–50 MW} & \multirow{2}{*}{2 s–5 min} & Response is fast, high specific power, high cost, difficult maintenance \\ \cline{2-5}  & & & & \\ \cline{2-5}  & High Energy Capacitor & 1–10 MW & 1–10 s & Response fast, high specific power, low specific energy \\ \cline{2-5}  & Supercapacitor & 10 kW–1 MW & 1–30 s & Response fast, high specific power, high cost, low energy storage \\ \hline \multirow{4}{*}{Electrochemical Energy Storage} & \multirow{2}{*}{10 kW–50 MW} & \multirow{2}{*}{min–h} & Mature technology, low cost, short life, environmental problems \\ \cline{3-3} \cline{5-5}  & & & & Long life, deep discharge, suitable for combination, high efficiency, good environmental protection, but slightly lower energy storage density \\ \cline{2-5}  & & & & \\ \cline{1-1} \cline{2-5}  & Sodium–sulfur battery [86] & \multirow{2}{*}{100 kW–100 MW} & \multirow{2}{*}{h} & Higher specific energy and specific power, high-temperature conditions, and operational safety issues to be improved \\ \cline{1-1} \cline{2-5}  & Li-ion battery [85] & \multirow{2}{*}{kW–MW} & \multirow{2}{*}{min–h} & Hour-high specific energy, group life, and safety issues need to be improved \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Related technical parameters. BMS is a real-time monitoring system composed of electronic circuit devices, which effectively monitors battery modules and single unit statuses (voltage, current, temperature, SOC, etc. ); safely manages the battery cluster's charging and discharging process, alarms, and emergency protection, processing for possible faults; and safely and optimally controls the operation of battery modules and battery clusters to ensure safe, reliable, and stable battery operation [89]. A BMS battery management system's hardware mainly consists of a BMU, BCMS, BMSC, HMI local monitoring unit, and DMU. BMS adopts tree management modes and supports EMS/SCADA and other upper computer master software management and scheduling [90]. An energy management system, or EMS for short, is used by power operators to monitor, control, and optimize the performance of a power generation or transmission system.