Volume 64

Estimation of Frequency Reserves Requirement & Evaluation of BESS Dispatch Strategy for the 2030 Italian Electricity Market Diego Andreotti, Usama Ch Muhammad, Filippo Bovera, Giuliano Rancilio

Abstract

In power systems with high shares of variable renewable energy sources (vRES), balancing generation and demand while maintaining frequency stability becomes increasingly challenging. Reduced system inertia and renewable variability require flexible resources capable of providing fast reserves and absorbing surplus energy. This study assesses the role of Battery Energy Storage Systems (BESS) in supporting the Italian power system in 2030 through two services: energy time-shifting and frequency reserve provision. Future reserve needs are estimated using two different approaches, formula-based and convolution-based, applied to historical forecast errors for load, solar, and wind generation. Both methods indicate a marked increase in reserve requirements from 2023 to 2030: under the formula approach, upward and downward reserves rise by 20% and 62%, while the convolution method estimates increases of 12% and 31%, respectively. Building on these results, the analysis simulates a BESS fleet, sized according to Italy’s NECP targets, operating under a price-driven dispatch strategy to assess its contribution to system balancing. Results show around 214 full cycles annually, delivering 11 TWh of peak-shaving energy and covering up to 50% of upward and 79% of downward reserves. Reserve provision peaks in spring and autumn, reaching up to 90% downward participation on weekdays, driven by strong renewable output and price signals. An economic evaluation suggests that the total reserve provision costs amount to approximately €185 million per year, with BESS accounting for €66 million per year. Overall, the findings highlight the strategic role of BESS as a dual-purpose resource delivering both energy arbitrage and ancillary services and offer insights to support future market design and grid stability in high-renewable systems.

Keywords: frequency reserve estimation; battery energy storage system; dispatching strategy; RES time shifting; 2030 NECP; renewable integration

Keywords frequency reserve estimation, battery energy storage system, dispatching strategy, RES time shifting, 2030 NECP, renewable integration