Future Light-Duty Vehicles: Predicting their Fuel Consumption and Carbon-Reduction Potential 2001-01-1081

The transportation sector in the United States is a major contributor to global energy consumption and carbon dioxide emission. To assess the future potentials of different technologies in addressing these two issues, we used a family of simulation programs to predict fuel consumption for passenger cars in 2020. The selected technology combinations that have good market potential and could be in mass production include: advanced gasoline and diesel internal combustion engine vehicles with automatically-shifting clutched transmissions, gasoline, diesel, and compressed natural gas hybrid electric vehicles with continuously variable transmissions, direct hydrogen, gasoline and methanol reformer fuel cell hybrid electric vehicles with direct ratio drive, and battery electric vehicle with direct ratio drive. Using appropriately researched assumptions and input variables, calculations were performed to estimate the energy consumption and carbon dioxide emissions of the different technology combinations. Comparing the results for the vehicle driving cycle only, an evolutionary fuel consumption improvement of about 35 percent can be expected for the baseline gasoline car, given only market pressures and gradual regulatory requirements. With more research and investment in technology, an advanced gasoline engine car may further reduce fuel consumption by 12%, and a gasoline electric hybrid by 40%, as compared to the evolutionary car. Diesel versions of the advanced combustion and hybrid vehicles may be 10-15% better than their gasoline counterparts. Compressed natural gas hybrid vehicle may reduce fuel consumption by 3-4% but may reduce carbon dioxide emission by 25%. Meanwhile, a direct hydrogen fuel cell electric hybrid vehicle may have the greatest improvement over the baseline at 55%, but the gasoline and methanol reformers fuel cell versions appear very expensive and offer little benefit. Finally, aside from critical battery limitations, the electric vehicle is difficult to compare to other vehicles without taking into account the electricity generation process.