Electrical Energy Storage Systems (EESS)

Electrical energy storage systems (EESS) for electrical installations are becoming more prevalent. EESS provide storage of electrical energy so that it can be used later. The approach is not new:

EESS in the form of battery-backed uninterruptible power supplies (UPS) have been used for many years. EESS are starting to be used for other purposes. There are several reasons behind the increasing use of EESS:

(a) they make renewable energy more effective by ensuring that the energy that is generated by renewable sources is available when that energy source is not available. EESS can be used either to ensure that all energy generated can be used locally in addition to the grid supply or to provide total independence from the public supply.

(b) they make energy available during loss of the grid supply, enabling, for example:

(i) 'controlled shutdown' of data centres and other computer and control systems to prevent corruption of stored data that would otherwise occur if the power was to be removed abruptly.

(ii) electrical and electronic products and infrastructure to be used during power outages.

(c) they allow for grid support services, including fast frequency response, demand and supply management, network constraints, and power quality management. These services could be aggregated over a number of sites and are not necessarily located on generation sites.

(d) the falling cost of EESS, notably lithium ion batteries.