A dynamic model for the optimal and sustainable development of the use of Compressed Natural Gas (CNG) buses in Tehran

Energy consumption management is essential because the natural resources should be preserved for the future people, and environment, the economy and the energy security of the country are also considered. Air pollution in Tehran has increased very much and thousands of people die every year because of it. In addition, the supply of diesel fuel under the current political circumstances of the country and the allocation of high value of subsidies to it have become a big problem for the government; the use of Compressed Natural Gas (CNG) buses for public transportation can be a solution to this problem. However, the CNG buses are not widely used in recent years. Based on historical approaches and using system dynamics (SD), the factors and feedback affecting the sustainable increase in the number CNG buses are identified in this paper and a dynamic model is introduced for the optimal and sustainable development of CNG buses. The model was validated and a 10-year period was simulated; according to the results, if the government does not increase the rate of its purchased CNG buses, the rate of the CBG buses being used now will be reduced from 38 percent to 14 percent in 2032. If 282 new CNG buses are purchased annually, the number of CNG buses and the number of diesel buses will be almost the same in 2032. Accordingly, fuel pollution produced by the buses and the fuel subsidies will be reduced.