摘要: |
As we enter the new millennium, the U.S. transportation sector is highly dependent on oil. Two options for reducing the petroleum dependence problem of the transportation sector exist, other than reducing travel demand: efficiency improvements and use of alternative fuels. Alternative fuels can be considered in two categories: nonpetroleum fossil energy resources and nonfossil energy resources and fuels. The focus of this paper is on alternative fuels, primarily for highway transportation, not on efficiency of vehicles. It is assumed that battery-electric, fuel cell, and grid-connected hybrid vehicles that will be commercially available in the future will consume some alternative fuels. Limited consideration is given to air transportation. |