There will be use of alternative fuels like bio-fuels, electricity, and hydrogen and strong government policies to overcome high costs and influence consumer choices. While achieving these goals will be difficult, improving technologies driven by strong and effective policies could make deep reductions possible.
"To reach the 2050 goals for reducing petroleum use and greenhouse gases, vehicles must become dramatically more efficient, regardless of how they are powered," Douglas M. Chapin, principal of MPR Associates, and chair of the committee that wrote the report, said.
"In addition, alternative fuels to petroleum must be readily available, cost-effective and produced with low emissions of greenhouse gases. Such a transition will be costly and require several decades," he added.
Improving the efficiency of conventional vehicles is, up to a point, the most economical and easiest-to-implement approach to saving fuel and lowering emissions, the report said.
This approach includes reducing work the engine must perform, reducing vehicle weight, aerodynamic resistance, rolling resistance, and accessories, plus improving the efficiency of the internal combustion engine power train.
Improved efficiency alone will not meet the 2050 goals, however. The average fuel economy of vehicles on the road would have to exceed 180 mpg, which, the report said, is extremely unlikely with current technologies. Therefore, the study committee also considered other alternatives for vehicles and fuels, including:
Although driving costs per mile will be lower, especially for vehicles powered by natural gas or electricity, the high initial purchase cost is likely to be a significant barrier to widespread consumer acceptance.
All the vehicles considered are and will continue to be several thousand dollars more expensive than today's conventional vehicles.
While corn-grain ethanol and biodiesel are the only bio fuels to have been produced in commercial quantities in the U.S. to date, the study committee found much greater potential in bio fuels made from lignocellulosic biomass-which includes crop residues like wheat straw, switch grass, whole trees, and wood waste.
Vehicles powered by electricity will not emit any greenhouse gases, but the production of electricity and the additional load on the electric power grid are factors that must be considered. To the extent that fossil resources are used to generate electricity.