The requirements and constraints of storage technology in isolated microgrids: a comparative analysis of lithium-ion vs. lead-acid batteries

Most isolated microgrids are served by intermittent renewable resources, including a battery energy storage system (BESS). Energy storage systems (ESS) play an essential role in microgrid operations, by mitigating renewable variability, keeping the load balancing, and voltage and frequency within limits. These functionalities make BESS the central core of the microgrid operation, and means that BESS technology is expected to satisfy a series of requirements and specifications. At the same time, the applied technology restrictions must be taken into account by the control systems which makes the operation more complicated. There are several battery technologies that are available in the market. Traditionally, isolated microgrids have been served by deep discharge lead-acid batteries. However, Lithium-ion batteries have become competitive in the last few years and can achieve a better performance than lead-acid models. This paper aims to analyze both technologies by examining the operational requirements for isolated microgrids, by taking account of factors such as life cycle, logistics, maintenance, and initial investment. It includes a case study of an isolated microgrid with a lead-acid energy storage system at Ilha Grande, Brazil. Simulations led to significant conclusions regarding the particular features of both technologies that were compared during the operation and took note of the logistical constraints imposed by the location under consideration.