Wind and solar power are important for sustainable energy, but they don't always produce electricity when needed. Compressed air energy storage (CAES) can help balance the grid by storing excess energy. This study looked at how efficient CAES is by analyzing data from a real CAES plant. They found that CAES can be more efficient than other power plants and can be a good option for storing energy in a 100% renewable energy system. It's important to consider both steady-state (constant) and dynamic (changing) conditions when evaluating CAES efficiency. Overall, CAES can be a valuable tool for long-term energy storage in sustainable energy systems.