Fluence to Provide Fast Reserve Grid Services for Terna

Fluence has signed a contract with Enel X for the delivery of two systems using the Gridstack™ energy storage product to provide Fast Reserve grid services for Terna, the Italian Transmission System Operator in Northern Italy. The systems, totaling 40 MW, are part of the first Fast Reserve auction in Italy and build on the Fluence team’s experience in Italy delivering a 1.4 MW/0.7 MWh battery energy storage system for Terna’s ‘Storage Lab’ in Codrongianos, Sardignia, and a 12 MW/72 MWh system for Terna’s ‘Large Scale’ project in Ginestra.

Fast Reserve grid services are vital to helping Italy meet its climate goals and supporting broader EU 2030 climate targets. The Italian electricity market is on the precipice of significant change as it prepares to start decommissioning coal plants. Decreased use of thermal generation reduces the amount of inertia available, which can lead to frequency variations on the electric grid if not addressed. By instantaneously charging or discharging power until primary reserves come online, Fast Reserve grid services help mitigate those variations, thereby enhancing grid resiliency and stability. Assets participating in the Fast Reserve service must respond within one second of an event and require advanced controls software to manage continuous bidirectional charging and discharging of the energy storage system. Fluence’s integrated, edge-based control software, Fluence OS, will provide these fast-response capabilities for Enel X.

Fluence and Enel have a long history of collaborating in Italy to deliver more resilient and sustainable electric systems. Members of the current Fluence team first partnered with Enel in 2012 to deliver the first ever European grid-scale stationary battery energy storage system to Enel Distribiuzone at the Isernia substation. In 2015, Fluence team members and ENEL partnered again to deliver the first grid-forming off-grid energy storage system on the island of Ventotene for Enel Thermal Generation.

“This award is the latest in the successful, continuous partnership between The Enel Group and Fluence focused on accelerating the speed and guiding the direction of the global clean energy transition,” said Panagiotis Stamoulis, Market Director, Southern Europe for Fluence. “As Italy and other countries in Southern Europe adopt innovative technologies to reach their decarbonization targets, energy storage systems with advanced software controls will play an increasingly significant role in enabling that transition while maintaining reliable and resilient electric grids.”

Since delivering Europe’s first battery energy storage system in 2012, the Fluence team has provided large-scale storage solutions to integrate renewable energy to the grid, enhance transmission and distribution services, and provide numerous other critical grid services in 13 countries in the region. A joint venture of Siemens and The AES Corporation, Fluence’s long experience and significant presence in Europe, including regional headquarters and a research lab in Germany, makes the company a preferred technology provider for utilities, IPPs, transmission system operators and financiers in the region.



In December 2020, the Enel Group has been awarded 59.2 MW of capacity contracts in the tender for Italian Transmission System Operator Terna’s ultra-rapid frequency regulation service, also known as Fast Reserve. Specifically, the awards relate to Italy’s central-northern mainland (40 MW) and central-southern mainland (19.2 MW).

The awarded capacity will be supplied by the so-called Fast Reserve Units (FRUs) which include the possibility of combining an electrochemical storage system with electric vehicle charging infrastructures and Vehicle-to-Grid solutions. Starting in January 2023 and through December 2027, these units will provide ultra-fast response service in less than one second. The service must be available for 1,000 hours per year, in specific time slots defined by Terna.

The Fast Reserve will help improve the stability of grid frequency, in coordination with other existing services. Within the pilot projects promoted by Terna, this tender helped to facilitate the introduction of new technologies in the electricity system and, in particular, electrochemical storage units, which are key in supporting the energy transition as envisaged by Italy’s Integrated National Energy and Climate Plan.

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