Shaping the future energy system through renewable integration and hydrogen adoption: the case of Lazio region in Italy

With an estimated population of 5.7 million and a gross domestic product of about €200 billion, Lazio is Italy's second-largest region and a major production hub. Its energy system still relies heavily on petroleum products, largely due to road transport, while renewables provide only about 21% of recent electricity generation. In response to climate objectives, the region has adopted an updated Regional Energy Plan aligned with the EU goal of climate neutrality by 2050. This study applies H2RES, an hourly-resolution, long-term energy optimization model, to assess the system transformation required to meet these targets. Two scenarios are examined: a Reference case reflecting current policy trajectories, and a more ambitious Green Deal case aligned with EU-level decarbonization objectives. Hourly modelling is crucial to evaluate the feasibility of high shares of variable renewables and to ensure reliability and security of supply throughout the transition. Special attention is devoted to hydrogen as a decarbonization vector and an enabler of sector coupling via PtX strategies. Results indicate that the Green Deal pathway achieves a 93% reduction in CO2 emissions by 2050 relative to 2019, compared with 47% in the Reference scenario, enabled by stronger electrification, expanded renewable deployment and deeper integration of hydrogen technologies.