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close this bookClimate Protection and the National Interest (WRI, 1997, 56 pages)
View the document(introduction...)
View the documentElectric Power Production
View the documentTransportation
View the documentZero Emission Vehicles: - Electric and Hydrogen Cars
View the documentHydrogen-Powered Fuel-Cell Vehicles
View the documentNext Steps


As we have seen, transportation is a major source of greenhouse gases and air pollution and the largest consumer of oil. Several measures would help solve all three transportation-related problems at the same time. As with power production, improving transportation efficiency is first on the list. If U.S. cars, trucks, and buses were more fuel efficient, oil consumption and carbon dioxide emissions would drop, less oil would have to be imported, and the rate of greenhouse warming would slow down. The good news is that the technology needed to greatly increase transportation fuel efficiency is largely in hand. If Americans gradually replace their gas guzzlers with more efficient vehicles, the risks associated with spiraling oil imports as well as the risks of climate change will decrease. The bad news is that the trend in new-vehicle fuel efficiency is downward, not upward, as consumers are buying more light-duty trucks (sport-utility vehicles, minivans, and pick-up trucks) to meet their personal transportation needs. About 40 percent of new personal vehicles fall into the light-duty truck category, and they are much less fuel-efficient than cars. (According to tests by Consumers Union, typical sport-utility vehicles have a fuel efficiency of about 10 mpg in city driving.) The average fuel efficiency of new cars and light trucks taken together peaked at 26.2 mpg in 1987 and had fallen to 24.8 mpg by 1995. (See Figure 14.) This drop in new-vehicle fuel efficiency combined with sustained growth in the number of drivers and vehicles add up to a continued increase in gasoline consumption. (See Figure 15.)


Improved new-vehicle fuel efficiency encouraged through market mechanisms would be an important first step toward reducing motor-vehicle CO2 emissions. For all its benefits, though, it seems unlikely that new-car fuel efficiency can rise fast enough to overcome the momentum of increased vehicle use. Motor vehicles depend totally on a depletable fossil fuel - oil. Until economically and technologically attractive alternative fuels become widely available, we will not be able to solve the problems engendered by motor vehicle use; consumers will have little alternative other than to continue buying oil-powered cars and trucks.

The world needs alternatives to oil-powered vehicles.56 And the burden for developing the technological alternatives rests squarely on the industrialized countries that make them: 80 percent of these vehicles are made in the United States, Japan, and Europe. No one else can do it. Various carbon-based fuels, burned in internal combustion engines (ICE), are being promoted as substitutes for gasoline to reduce air pollution. These fuels include blends of gasoline and methanol (wood alcohol) or ethanol (grain alcohol, made from corn) and compressed natural gas (CNG). Methanol (as presently produced) and CNG are based on fossil fuels, and their use is not sustainable over the long haul. Moreover, they offer little if any improvement over gasoline in reducing greenhouse gas emissions. As for air pollution, CNG offers benefits while methanol-gasoline blends could actually increase ozone formation. The widespread deployment of methanol or CNG in ICE vehicles should not be encouraged.


Ethanol produced from corn, for use in gasohol, is also not a long-term solution. In 1995, about 9 percent of the motor-vehicle fuel pumped at service stations in the United States was gasohol, a mixture of 10 percent ethanol and 90 percent gasoline. Ethanol production is heavily subsidized by the federal government ($0.54 per gallon) and various agricultural states. Gasohol probably offers no ozone benefit.57 And it takes large amounts of fossil fuels to make. Under very favorable circumstances, ethanol derived from corn has an energy ratio of only 1.24.58 That is, ethanol production yields only 24 percent more energy than is used in making it.

Viewed solely as a means of cutting air pollution, these fuels have varying degrees of merit. All three would reduce carbon monoxide emissions relative to conventional gasoline. CNG would also reduce ozone concentrations. But when the impact of these fuels on global warming is taken into account, their attractiveness fades.