Energy Storage Valuation Under Different Storage Forms and Functions in Transmission and Distribution Applications

In this paper, we analyze and quantify functional value streams of energy storage under different forms (state in which energy is stored) and network location (e.g., transmission or distribution sides). First, we consider a transmission-connected thermal form of storage coupled with concentrating solar power. Using the California power grid as a case study, we show that the coupled unit is significantly less volatile in its response and, through its load following, day-ahead dispatching, and regulation capabilities, it produces significant cost savings. Another case study examines the value of the electrical form of storage in a distribution network and in coupling with photovoltaics. The energy storage is used to mitigate component overloads and to reduce the subsequent infrastructure investments, and smooth out the intermittency of renewable generation. Storage value is quantified formally and under optimal control configuration of storage charge and discharging. Finally, a case study is constructed to examine the functional value of substation-sited storage with respect to investment deferral for the substation transformer.