**Abstract**

Renewable energy resource like solar and wind have huge potential to reduce the dependence on fossil fuel, but due to their intermittent nature of output according to variation of season, reliability of grid affected therefore energy storage system become an important part of the of renewable electricity generation system. Pumped hydro energy storage, compressed air energy storage, flywheels, capacitors, and super conducting magnetic storage technologies have been developed, but many of these are limited in their capacity, characteristics and site dependence. Currently battery energy storage system is not much adopted within grid, but with development their density, versatility and efficiency it is observed that BESS- (battery Energy Storage system) will be adopted in large quantity.

**Keywords:** energy storage, pumped hydro energy storage, compressed air energy storage, flywheels, capacitors, super conducting magnetic storage technologies renewable electricity generation

### **1. Introduction**

Energy demand for single consumer to power station is varying throughout the whole day, and there is variability and uncertainty in the power quality, also there is imbalance of energy demand and supply which is completed using fossil fuels. These create environment pollution and global warming effects, that's why our main focus is diverted towards renewable energy resources; on the other hand these are variable and intermittent nature of energy generation so for their flexibility, stability and reliability energy storage technologies are put into practice. By transmitting the stored energy temporal as well as geographic gaps between demand and supply can be filled, also the areas having poor energy infrastructure or not electrified can be energized with the reliable source of energy storage (ES) [1]. Also, as there is no direct connection between consumer and electricity generation sources, Whole power generated at power station doesn't reach to the consumers, and large amount of energy is being lost in the form of losses, in this way current gird system become inefficient. System can be made more efficient by using battery energy storage system in gird, by running plants near to their full capacity, and also by using maximum amount of power generated at power stations [2]. In power distribution system battery energy storage system is provided in two ways, either storage is provided at distribution substation or at distribution feeder also SCADA (supervisory control and data acquisition) equipment, control schemes, and economics of scale can easily access using centralized storage technologies [3]. Power quality is maintained easily with the installation of comparatively sized batteries in the installation of large solar PV plants, battery energy storage control system is done either automatically or using solar couple system [4]. Majority of energy storage within grid is present in the form of pumped hydro storage plants about 125 GW, it makes about 3% of global power capacity [5]. Pumped hydro energy storage, compressed air energy storage, flywheels, capacitors, and super conducting magnetic storage technologies have been developed, but many of these are limited in their capacity, characteristics and site dependence. Currently battery energy storage system is not much adopted within grid, but with development their density, versatility and efficiency it is observed that BESS will be adopted in large quantity [6].
