EXPLORING DECARBONISATION STRATEGIES FOR THE ITALIAN ENERGY SYSTEM Techno‑Economic Optimisation, Uncertainty Analysis and Input–Output Macroeconomic Analysis

The decarbonisation of national energy systems is a central challenge in addressing climate change. This thesis contributes to the analysis of decarbonisation strategies for the Italian energy system by 2050, addressing three methodological gaps identified in the existing literature: limited combination of spatial resolution and whole-energy sectoral integration with computational tractability, insufficient systematic treatment of parameter uncertainty, and scarce macroeconomic impact assessment with sectoral disaggregation. The study builds upon the open-source EnergyScope capacity expansion optimisation frame- work, extending it with enhanced spatial resolution (six regions corresponding to Italian electricity market zones), electricity transmission constraints, detailed renewable technology options with region-specific generation profiles, and improved transport sector representation. The enhanced model maintains computational efficiency suitable for extensive scenario exploration while cov- ering all energy sectors. It was applied to design a cost-optimal deep decarbonisation scenario imposing a constraint of 95% emission reduction compared to 1990 levels. The results identify four principal transition levers: extensive electrification of end-use demand driving electricity consumption to 469 TWh; massive renewable deployment dominated by solar PV (190 GW) and wind (42 GW), complemented by nuclear power (14 GW); enhanced system flexibility through electrical and thermal storage; and bioenergy and hydrogen utilisation for hard-to-abate sectors. The regional analysis reveals pronounced north-south patterns, with southern regions emerging as primary electricity exporters and northern regions relying on inter-regional imports. To address parameter uncertainty, Monte Carlo analysis was combined with clustering and decision tree methods, revealing robust deployment of solar PV and onshore wind across scenarios, while highlighting key trade-offs between battery storage and nuclear power. Finally, the Input-Output analysis quantified the macroeconomic impacts, estimating 130 bil- lion e in cumulative value added and 2.03 million FTE of employment from construction and manufacturing investments (2019–2050), plus 3.0 billion e/year and 51 000 permanent jobs from operation and maintenance. The fossil fuel phase-out achieves annual cost savings of 73 billion e but generates supply chain losses of 17.8 billion e/year in value added and 262 000 jobs.