Concerns related to climate change and security of energy supply is pushing various countries to make strategic energy planning decisions. In this regard, energy system modelling is an appropriate method to find out the utilization of current declining non-renewable energy resources and other possible scenarios. Consequently, it is available to consider various aspects of energy system decisions and some probable alternatives. This paper investigates different scenarios for Iran's electrical energy system applied in LEAP. Two different demand forecasting methods are used and the effects of applying four supply- side scenarios on CO2 emissions from power sector are finally compared. Manuscript profile