An energy management system and a method of operation thereof are provided. The energy management system includes a receiver that receives power amount information indicating an amount of power generated by a first new and renewable energy power plant, an amount of power stored in a first energy storage device for the first new and renewable energy power plant, an amount of power generated by a second new and renewable energy power plant, and an amount of power stored in a second energy storage device for the second new and renewable energy power plant and a controller that determines an operation mode for each of the first energy storage device and the second energy storage device based on the received power amount information.