On the environmental effectiveness analysis of energy policies: A case study of air pollution in the megacity of Tehran

Abstract

The present study compared different approaches to assessing the environmental cost-effectiveness of energy policy scenarios. As a case study, the megacity of Tehran in Iran was studied. A key policy challenge in this city is to curb high concentrations of PM2.5 and mitigate the associated adverse impacts. The results demonstrated that in the business as usual case, the spatially averaged primary and secondary PM2.5 concentration in Tehran will increase by 30% in the 2010–2030 period. Adopting certain planned policy scenarios and the corresponding pollutant concentration reductions in Tehran shows that although most of the emission comes from industrial activities around the city, the distribution of the transportation emission sources may play the most effective role in decreasing pollution levels in transport-related energy policies. Next, based on environmental damage costs and abatement costs in different pollution mitigation scenarios, the best (most environmentally cost-effective) scenarios were evaluated. The eco-efficiencies of the energy policies were assessed based on two proxies of environmental impacts: the reduced damage cost as a function of the reduced emission rates of the pollutants and the decreased number of polluted days in the year. In a sample area in which the simulated concentrations were verified by local measurements, the most efficient mitigation scenario would decrease the average concentration of PM2.5 by 35% in 2030 and the number of polluted days by 20%. These findings indicate how far the linear functionality of the damage cost from emission levels may mislead environmental impact assessments. This is due to neglecting the source distribution effects and geographical conditions of the environment.