Sperling, Daniel, Mark A. DeLuchi, Michael Q. Wang (1990) Toward Alternative Transportation Fuels. Institute of Transportation Studies, University of California, Davis, Presentation Series UCD-ITS-RP-90-04
Transportation energy issues are moving to the forefront of the public consciousness in the U.S. and particularly California and gaining increasing attention from legislators and regulators. The three principal concerns motivating this interest in transportation energy are urban air quality, energy security, and global warming. Transportation fuels are a principal contributor to each of these. The transportation sector, mostly motor vehicles, contributes roughly half the urban air pollutants and 34% of the carbon dioxide in California, and consumes almost 3/4 of all petroleum.