Technical Description

Electricity storage is a key technology to enable the next phase of the energy transition, driven by the large-scale deployment of variable renewable energy sources (VRES) like solar and wind power. The technologies presented in this chapter will help to cope with the integration challenges arising from intermittent generation sources: the need to ensure the balance of production and consumption in real-time maintain the quality of supply and store excess electricity over different time horizons (minutes, days, weeks).

The services electricity storage can provide are various and are inherently related to the physical characteristics of the storage media and the storage system. The different storage systems can be classified into two main categories based on their power rating and discharge time at rated power:

• Power-intensive applications are required to provide ancillary services to the system in maintaining the balance of frequency and voltage or providing power quality. Power intensive applications do this by delivering large amounts of power for time periods on the scale of seconds or minutes, and thus, they are characterized by a high ratio of power to energy (short discharge times) and fast response.
• Energy-intensive applications are used for storing large amounts of energy to match demand and supply, perform load levelling or reducing congestion in the network. These technologies are characterized by a lower ratio of power to energy (long discharge times) and used on an hourly to seasonal scale.

System power rating versus discharge time at rated power for different storage technologies

Components and their categorization for cell-based batteries, such as Li-ion, NaS and NaNiCl.

Components and their categorization for Vanadium-redox flow battery