This research assesses the Ecuadorian power generation system, estimating the electricity supply and demand forecast until 2040. For this purpose, three potential alternative scenarios were analyzed using the Long-range Energy Alternatives Planning (LEAP) System; S1: Business As Usual; S2: Power Generation Master Plan; and S3: Sustainable Power Generation System. The main goal of this study is to analyze the possible alternatives for electricity supply and demand, fuel consumption, and the future structure of the Ecuadorian power generation system to transform the current system based on petroleum fuels into a sustainable system that consumes natural gas, and progressively introduces renewable power generation plants such as solar, wind, biomass, and hydroelectric until 2040. According to the estimated results through the inclusion of sustainable energy policies, S3 scenario relative to S1 scenario could reduce the average CO 2 equivalent (CO 2 e) emissions by 11.72%, the average production costs by 9.78%, and the average petroleum fuel consumption by 15.95%. Consequently, a correct energy transition contributes to the protection of the environment and public health and has a direct effect on economic savings for the state, which benefits to improve the citizen's quality of life.