Optimal sizing of distribution-scale energy storage

Global warming and reliability concerns have intensified the interest in developing energy storage technologies. Energy storage has the potential to reduce carbon emissions by decreasing electricity demand from power plants, increasing the reliability of electricity supplied to customers, and saving costs by deferring upgrades of overloaded systems. Current efforts to implement storage are limited because existing power systems have a large generation capacity that can ordinarily match system demand; thus, it is difficult to justify the economic gains of storage technologies in an already interconnected network. However, with the rise in electrification and variable renewable energy sources such as wind and solar power, the value proposition of storage might be changing, especially in local distribution systems. As such, more advanced modeling techniques are needed to assess the technical and economic feasibility of integrating batteries into electric grids. This study uses REopt (Renewable Energy Integration and Optimization), a comprehensive and accurate optimization tool developed by the National Renewable Energy Lab, to quantify the energetic, environmental and economic impacts of distributed energy resources in Austin Energy’s power portfolio. Austin Energy is a municipal electric utility owned and operated by the City of Austin, which is the state capital of Texas. This study’s findings suggest that the value of utility-scale energy storage is expected to increase with future load growth on the grid and as extreme weather events become more catastrophic. We show that batteries as small as 1MW can increase reliability of the grid; however, a larger battery is more profitable by providing higher savings from energy arbitrage and 4 Coincident-Peak (4CP) avoidance. Our results demonstrate that a battery is only economical if it can perform 4CP avoidance and although perfect foresight of 4CP events is useful, it is not that important when considering the value of storage. In summary, there are promising opportunities for energy storage as small as 1MW in providing economic savings and resilience benefits to overloaded feeders in Austin Energy’s distribution network.Mechanical Engineerin