The operation and maintenance fee of an energy storage power station can vary significantly based on several factors. Costs can range from $20 to $40 per kilowatt per year, depending on the technology and infrastructure in place. Let's peel back the curtain on their operating costs – the unsung spreadsheet warrior of renewable energy. Furthermore, the document discusses future trends in energy storage. . In this work we describe the development of cost and performance projections for utility-scale lithium-ion battery systems, with a focus on 4-hour duration systems.