Energy storage technologies are crucial for stabilizing electricity supply and integrating renewable energy sources. To ensure grid stability, around 15% of capacity should come from energy storage. The main technologies include pumped storage hydropower, compressed-air storage, and batteries. Pumped storage hydropower is the most common, often supporting nuclear power. Smaller-scale options like supercapacitors and flywheels are also used. Overall, energy storage plays a key role in managing peak demand and intermittent renewables.