Comparison of Energy Storage Technologies for Isolated Community Microgrid Applications

Abstract

The International Energy Agency estimates that by the year 2040 there will still be more than 700 million people worldwide without access to electricity. Renewable energy production, particularly from photovoltaic systems, combined with affordable and effective energy storage provides a means to provide electricity to these poorer communities. This paper explores four battery energy storage system (BESS) technologies to support a notional, isolated village microgrid requiring a BESS capable of providing 605 kWh of usable storage over a 20-year scenario timeframe. Using this analysis scenario, the lead-acid battery is analyzed as a baseline against the current technology leader, the liquid electrolyte lithium-ion battery (LIB), and another current option, the vanadium redox flow battery (VRFB). The solid-state LIB is also reviewed as a future technology. The BESS technologies are analyzed in two parts. First, a cost analysis considering factors affecting initial battery bank sizing (depth of discharge limits, efficiency, capacity fade) as well as battery life which drives replacement frequency, and operations and maintenance costs for the years 2018 and 2025. Second, an analysis of four other significant factors not included in the cost analysis: energy density, operating temperature limits, safety issues, and environmental concerns. The findings show that the liquid electrolyte LIB is the current leading technology due mostly to its ever lowering cost, despite continued concerns over its safety. The VRFB is presented as a safer alternative that features a system lifespan several times that of the LIB, the capability to operate at high temperatures without cooling subsystems, and a much lower environmental impact. If VRFB manufacturers can achieve lifecycle cost reductions to achieve more parity with LIBs, these advantages may sway system designers to choose this technology.

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