Optimal control and techno-economic analysis of long-duration battery energy storage system applications

Long-Duration Battery Energy Storage Systems (LD-BESSs) are considered a viable solution for electric bill management, support to renewable energies, and grid services. However, the cost of this technology is still considered high. This work connects traditional Techno-economic analyses (TEA) with optimal control theory, with the aim of integrating the optimal control policy into traditional TEA for a more accurate evaluation of the benefits of an investment based on LD-BESS. A Dynamic Programming (DP) optimization algorithm is developed to establish the optimal control policy of the BESS, aiming to minimize utility costs through energy arbitrage and peak shaving. The three main scenarios are defined and calibrated using real-world data from a commercial building, a wind turbine, and electricity prices. Financial viability is assessed using the Levelized Cost of Storage (LCOS). Results showed that the BESS has significant potential for reducing utility bills, with savings of up to 20.4% in a standalone configuration and 32.4% when coupled with wind generation. However, the economic analysis reveals that under current cost assumptions, the cost of storage exceeds the savings and revenues, limiting the profitability for these applications. The findings point out the operational benefits of LD-BESSs for commercial buildings while highlighting the need for further cost reductions to ensure economic feasibility.