M. Shafie-Pour - PhD Faculty of Environmental Engineering, University of Tehran
R. Mostofi Daryani - Postgraduate Students of Environmental Engineering, University of Tehran.
M. Negahban Azar - Postgraduate Students of Environmental Engineering, University of Tehran.

Around the world, transportation relies on oil and partially gas for virtually all its fuel, and accounts for almost half of the world oil consumption. Its strongly upward trend in oil demand and pollutant emissions in countries around the world over the past decade, shows no signs of slowing. Private-car ownership rates increase steadily with rising incomes, particularly in emerging economies. These are the major challenges for sustainability within the transportation sector addressing the interactions between energy and environment. These trends portend a future fraught with potential difficulties. Secure energy supply is an on-going concern and priority policy issue. Concern continues to grow over emissions from fossil fuel combustion and the effects of CO2 and other greenhouse gases on the global climate. Of course, governments and industries have been aware of the implications for transportation for sometimes and efforts are being made to change the present course. Policies to improve light duty vehicle fuel efficiency have been adopted in many countries. More climate-friendly propulsion systems and new fuel alternatives are under development. Hydrogen and fuel cells are increasingly seen by industry and governments as the technology combination that will eventually lead to non-oil, less pollutant and zero-CO2 transport system some day in the future. But in the nearer term, over the next 10-30 years, it seems that current activities and policies will do little to significantly change current trends. In this paper, a combination of two major policy approaches for reducing fuel consumption and emissions in the transport sector are presented. Detail of policy for reducing "emissions per unit of fuel" consumed and reducing "fuel consumption per unit of movement" have been analyzed. Because of the main portion of transportation in both energy consumption and increasing emissions, aggressive actions in these two areas, as a consequence of implementation of both of the proposed policies in this paper of global level, could lead to downward sloping trends by a conservative estimate of 20% in the world transportation oil use, emissions and greenhouse gases by 2030, at a lower rather cost than is commonly believed.

energy, transportation, emission, consumption, vehicle, efficiency