Siemens has successfully tested and put in operation a turnkey Siestorage battery storage system on behalf of Italian energy utility Enel. The system is integrated in the island power station located on the Mediterranean island of Ventotene. All components are integrated directly in the island’s supply network and, thanks to an intelligent control unit, developed together with Enel, provides for more economical and efficient operation of the entire energy system. In addition, Siestorage uses integrated converters to stabilize the frequency and voltage of the island’s network. The delivery package also includes the transformers and low-voltage switchgear. The lithium-ion battery-based storage system has an output of 500 kW and a storage capacity of 600 kWh.
The Mediterranean island of Ventotene has an area of 153 hectares and is located about 100 kilometers south of Rome. It is not connected to the Italian national power supply grid, and until now the island’s power supply has been provided by four diesel generators and distributed residential PV power plants. The island network management is guaranteed by the intelligent control unit that provides for the optimal interoperation of storage system, generation, and consumption, which are continuously adapted to the actual demand. This ensures that the diesel generators in particular can be used in a more efficient operating mode because short-term peak loads are covered by power from the storage system and not from the generators. During off-peak periods, it is even possible to switch off the diesel generators completely. This saves fuel, extends the service life, minimizes maintenance, and reduces the stock of fuel reserves. The result is lower CO2 emissions and significantly reduced consumption of diesel fuel, which has to be specially transported to the island from the mainland.
The implementation of Siestorage in the Ventotene network is additionally intended to balance out frequency and voltage fluctuations by means of the converter integrated in the storage system, and thus stabilize the island network. In addition, this prepares the network for future applications, such as charging stations that can charge electrically powered transport vehicles. Another objective is to increase the capacity of the entire island network so that it can absorb fluctuating energy from renewable sources more effectively. The storage system also helps with maintenance of the generators, because they can be disconnected from the network during maintenance periods while the new system temporarily takes over the supply. Finally in the possible event of a blackout, Siestorage can help perform a controlled start-up of the island network, thanks to its black-start capability.