Iranian Journal of

Background and Objective: Transportation sector generates the largest share of greenhouse gas emissions (CO₂ and CH₄) which causes global warming. “Stop-and-go” driving and congested traffic flow results in a decrease in average car speeds, an increase in traffic incidents, and finally escalates GHGs emissions. Hence, congestion is directly related to carbon emissions. The objective of this study was to estimate the GHGs emissions of urban transportation sector using the congestion index.
Materials and Methods: The traffic flow in the main street of Hamadan city was continuously monitored in 8 time periods from 8 am to 12 pm in August 2018. Then, a traffic congestion map was prepared. Subsequently the surface area and weight coefficient of each road were obtained based on the traffic assignment model. Finally, the amount of GHGs emissions from transportation sector, CO₂ emission per capita, and annual amount of CO₂ and CH₄ release in each street were calculated and estimated.
Results: Results showed that the total CO₂ and CH₄ emissions from the transportation sector of Hamadan city are 776000 and 396 ton/year, respectively. Imam Khomeini Highway (29166 ton CO₂/year) and Mirzadeh Eshghi Street (24453 ton CO₂/year) recorded the highest level of carbon emission due to the highespeed and more width “stop and go” driving conditions.
Conclusion: The conformity of the congestion index with the traffic assignment model can be used to estimate the amount of urban traffic pollution. Finally, because of the high growth rate of CO₂ and CH₄ and the role of forests in maximizing carbon sequestration, it is imperative to manage and increase green spaces to reduce CO₂.

Background and Objective: Assessing the life cycle and evaluating the carbon footprint in thermal power plants is crucial due to their reliance on fossil fuels. This study was conducted to evaluate the environmental impacts and carbon footprint of the Iranshahr steam power plant.
Materials and Methods: Primary data were collected and analyzed using SimaPro software and the ReCiPe 2016 method (Hierarchist perspective). The carbon footprint was assessed through data modeling based on the International Panel on Climate Change (IPCC) method. The functional unit was defined as one kilowatt-hour (kWh) of electricity generated, and the system boundary was set as gate-to-gate.
Results: The study revealed that the most significant environmental impacts of the power plant were related to human carcinogenic toxicity, accounting for 42% at the midpoint level, and damage to human health, contributing 86% at the endpoint level. Sensitivity analysis identified natural gas as the most influential factor affecting the results. According to the IPCC method, fossil fuel consumption contributed 94% to the global warming potential. The highest amount of CO₂ emitted was 0.946 kg per kWh of electricity produced.
Conclusion: The CO₂ emissions per kWh of electricity produced (0.946 kg/kWh) exceeded the average CO₂ emission factor for fossil fuel power plants in Iran (0.64 kg/kWh). Based on these findings, it is recommended to prioritize the use of renewable and clean energy sources, such as wind and solar power, as alternatives for electricity generation in the region.