This case study delves into the innovative role of Battery Energy Storage Systems (BESS) in stabilising and supporting modern grids, with a particular focus on a large-scale BESS project undertaken by Tata Consulting Engineers (TCE). BESS is changing the way cities make, store, distribute, and use electricity by connecting intermittent renewable generation with changing urban energy demand. This review explores the diverse applications of BESSs across different scales, from. Battery energy storage systems (BESSs) are central to integrating high shares of renewable energy and meeting the exponential demand growth of data centers while improving grid sustainability, stability, reliability, and resilience. Integrating renewable energy into the grid presents challenges of.