This study aims to analyze the electricity generation and its environmental aspects in Tehran city by using the LEAP model and developing two scenarios, including Business-As-Usual and Sustainable-Waste-Management (SWM). The base and final years of the planning are 2012 and 2035, respectively. It is attempted to integrate two models of IPCC (Intergovernmental Panel on Climate Change) for methane flow rate estimation and LEAP to estimate Tehran’s energy and non-energy emissions. By linking these two models, the energy and environmental effects of the SWM scenario are estimated. To calculate the power production of the landfill gas (LFG) plants, the gas turbine model of GE10 is selected, and an Engineering-Equation-Solver (EES) code is developed based on methane flow rate and composition data obtained from the IPCC default method in the SWM scenario. The combination of EES codes and LEAP analysis shows that the LFG plants can supply 0.5 GW h power, which is 1.4% of the total demand in 2016, but it will raise to 0.9 GW h in 2035. Although utilization of LFG plants increases the cost of electricity production, the accumulated difference of 100 years global warming potential in the studied scenarios will be 81.2 Mt CO₂ equivalent from 2012 to 2035.