Techno-economic Assessment for Optimal Energy Storage Mix

A wide variety of energy storage methods are currently employed around the world, including electrical storage, thermal storage, chemical storage. The correct storage mix will satisfy a range of constraints relating to the specific nature of electricity generation and demand connected to the grid, the physical nature of the landscape and it's geology as well as the political environment. Finding synthesis among these conflicting concerns is a difficult task and the lack of a clear vision for energy storage can lead countries to adopt a disjointed approach to energy storage. This paper addresses this by presenting a framework based on the Analytical Hierarchy Process (AHP) that may be used to identify the most attractive storage mix for three scenarios: renewable integration, load shifting and power quality. Our analysis shows that for the power quality scenario, the most appropriate choices are supercapacitors, SMES and flywheel storage. For renewable integration the best options are pumped hydro and hydrogen storage. Both technologies are able to store excess renewable energy for relatively long period, making them an ideal way to deal with the intermittency of renewables. For load shifting purposes, pumped hydro storage is the optimal choice but limited due to the number of new storage sites available to construct, followed by thermal storage and batteries (VRB, ZnBr and NaS). These technologies are characterized by quick response time, high power density and low losses.