Abstract In 2021 the European Commission has proposed the Fit-for-55 policy package, requiring European countries to reduce their CO2 emissions by 55% with respect to 1990 by the year 2030, a first step to achieve carbon neutrality by 2050. Energy system modeling can be a valuable tool for national policymakers to choose the most appropriate technologies to achieve these goals efficiently. This article presents a model of the Italian power system realized employing the open energy modeling framework, Oemof. A linear programming optimization is implemented to evaluate how to minimize system costs at decreasing CO2 emissions in 2030. The developed tool is applied to evaluate different research questions: (i) pathway towards full decarbonization and power self-sufficiency of the electricity sector in Italy, (ii) relevance of flexibility assets in power grids: li-ion batteries, hydrogen storage and transmission lines reinforcement. A 55% CO2 emissions reduction for the actual Italian power sector can be achieved through an increase of 30% of the total annual system cost. Achieving complete decarbonization and self-sufficiency increases significatively annual expenditures. However, cost mitigation is plausible through the integration of sector coupling methodologies or the adoption of a broader spectrum of technological solutions. Flexibility measures appear instrumental for decarbonization, particularly transmission lines, demanding a substantial expansion beyond the stated plans for 2030. This infrastructure is crucial in Italy to facilitate the transfer of renewable electricity generated in the Southern regions to the Northern areas, where a large portion of the electricity demand is located.