Climate change is a worldwide issue which is causing several difficulties and consequences both at human and environmental level. The energy sector is one of the main contributors to greenhouse gas (GHG) emissions and thus policy challenges are the main tool to contain this crisis. Indeed, a necessary path to intervene is the transition from traditional fossil fuels use toward the renewable sources, therefore leaving the carbon-based electricity generation in favour of an energy mix based on a higher renewable share and the residual part on gas. The aim of this thesis is to elaborate an energy model of the Italian energy system by performing long-term planning of energy evolution.