This thesis analyzes the energy transition of the Yukon territory in Canada, with the aim of studying the lowest-cost decarbonization pathways. The analysis is framed within the objectives defined by the government's “Our Clean Future” plan, which aims to reduce the environmental impact of an energy system characterized by a strong dependence on fossil fuels and the presence of isolated communities. To achieve this goal, a multi-sector energy optimization model was developed using the open-source PyPSA framework. The model integrates the electricity, heating, and transportation sectors with hourly resolution, simulating investment decisions over a five-year time horizon (2025-2029). Several scenarios were then defined and compared: a “Baseline” scenario to represent the current state, a purely economic optimization scenario (“Business-As-Usual”) and a series of scenarios that implement the specific targets of the “Our Clean Future” plan, such as limits on CO2 emissions and the adoption of a minimum number of heat pumps and electric vehicles.