Large-scale energy storage systems: a comparison on strategies and policies in European countries

Each European Country promotes the use of Renewable Energy Sources (RESs) to meet decarbonisation targets, but not all pay the same attention to the flexibility needs required by the power systems. RES plants are usually non-programmable and characterized by a discontinuous and variable production overtime. They are not suitable for meeting the electricity demand at any time and they cause different technical problems in the power system operation (e.g. imbalances, congestion and reversal flows). Energy Storage Systems (ESSs) can be a possible solution to these issues, because they can merge energy generation and demand and provide flexibility services to the power systems. Nevertheless, there are some obstacles to the large-scale deployment of ESSs, first the high investment capital cost and the lack of a clear regulation. Thereby the ramp-up of the necessary ESSs capacity has to be market-driven by proper government policies. This paper is aimed to provide an overview on three European Countries that are the first ones moving towards this process on policies and strategies for guaranteeing the suitable spread of ESSs in power systems: Italy, Germany and Spain. A comparative and critical analysis is reported and, for each Country, some data on current and planned ESS capacity are reported and commented. A specific focus is made on the Italian design of a Capacity Market (CM) dedicated to ESSs, called MACSE (“Mercato a termine degli stoccaggi”), that is the first and only mechanism present at European level for supporting long term investments on ESSs integrated in power systems.