Electricity demand in the Islamic Republic of lean will continue to increase dramatically in the future due to the rapid pace of economic development leading to construction of new power plants. All forms of electricity generation have some level of environmental impact, such as air pollution, water resource use, water discharge, solid waste generation, and land resource use, and greenhouse as emission. Concerns about greenhouse gas emissions affect decision-making about construction of new power plants. Comparison of different kinds of power plants indicates that nuclear power is not directly emitting greenhouse gas emissions. So nuclear power plants could be a suitable replacement for thermal power plants. Of course, renewable power plants could be used too, but the capacity of nuclear power plants is almost more than renewable power plants. Power plants in Iran are mainly thermal, burning fossil fuels, which emit a great deal of pollutants and greenhouse gases. The only nuclear power plant of Iran (Bushehr nuclear power plant) will be operating in 2009. This article attempts to interpret the role of Bushehr nuclear power plant in the CO2 emission trend of the power plant sector in Iran.