Currently, in the countries where Enel Green Power operates, wind and solar plants supply energy to the grid predominantly during the day, while at night thermoelectric plants take over. The most commonly used energy storage systems, are lithium batteries that have a very rapid response capacity but offer a relatively limited energy contribution lasting only a few hours. This type of battery is used mainly to provide flexibility services to the grid and to ensure an adequate supply of energy at the most critical times, but they do not store large volumes of energy due to the high unit cost of batteries compared to the value of the energy stored.Enel Green Power is awarded approximately 1.1 GW of contracted capacity in Sardinia, which it will honor by installing around 1.6GW/6.6GWh of new capacity in energy storage systems by 2024. Half the capacity will be installed in Sardinia, without recourse to new gas plants and therefore taking a significant step forwards towards the transformation of Sardinia into a green island. In total, Enel Green Power has more than 52GW of BESS projects in development worldwide and more than 2.7GW under construction or in operation.As the use of renewables increases, there is an ever greater need for energy storage systems that can ensure durability and flexibility to the grid. In order to function effectively, the electricity system must be able to ensure the balance between energy production and consumption at all times, as well as to deal with unexpected events in terms of supply and demand. This requires flexible resources capable of modulating production based on actual energy needs. As renewables progressively replace thermoelectric power stations, we need new solutions that meet flexibility and adequacy requirements. This is exactly what energy storage systems can do, because they’re able to store the surplus energy produced and return it to the system when needed. When combined with renewable energy plants, they can provide a source of energy that is not only clean, but also flexible and reliable.