Motor Vehicles, Fuels and the 1990 Clean Air Act

The Clean Air Act set a national goal of clean and healthy air for all. It established for the first time specific responsibilities for government and private industry to reduce emissions from vehicles, factories and other pollution sources.

In many ways, this far-reaching law has been a great success. Today's cars, for example, typically emit 70 percent to 90 percent less pollution over their lifetimes than their 1970 counterparts.

Air Pollution Emissions from
U.S. Passenger Cars and Light-Duty Trucks
Using Gasoline, 1995

Carbon
Dioxide

Carbon
Monoxide

Methane

Nonmethane
Organic
Compounds

Nitrous
Oxide

Nitrogen
Oxides

Percent of Greenhouse Gases Caused by Passenger Cars and Light-Duty Trucks Using Gasoline

Despite considerable progress, the overall goal of clean and healthy air continues to elude much of the country. Unhealthy air pollution levels still plague virtually every major city in the United States. This is largely because development and urban sprawl have created new pollution sources and have contributed to a doubling of vehicle travel since 1970. Furthermore, scientists and now the public have become concerned about previously unrecognized environmental threats such as acid rain and air toxics.

With these issues in mind, Congress in 1990 amended and updated the Clean Air Act Amendments for the first time since 1977. The 1990 Clean Air Act includes provisions to further control urban smog, carbon monoxide and diesel particulates and to address air toxics and acid rain. Motor vehicles contribute to all these problems. The mobile source provisions of the 1990 law are targeted to reduce most vehicle-related pollutants by more than 40 percent.

Gasoline and diesel fuel are both produced from crude oil. Together, gasoline and diesel fuel power 99 percent of this country's motor vehicle fleet. Past efforts to reduce vehicle emissions ignored petroleum fuels and focused on the development of sophisticated engine and vehicle emission control systems involving catalytic converters, on-board computers and other hardware. It became apparent, however, that fuel composition and type are also critical factors in the clean vehicle equation.

The Clean Air Act of 1990 explicitly recognized that changes in fuels as well as vehicle technology must play a role in reducing air pollution from motor vehicles.

The recognition that fuels are significant opened up an interesting debate about the relative merits of petroleum and nonpetroleum fuels. Petroleum fuels have many advantages as vehicle fuels. Oil can still be discovered and pumped from the ground in many parts of the world for as little as ten or twenty cents per gallon. Gasoline and diesel fuel pack more energy per gallon than other fuels. Most importantly, our country's vast transportation infrastructure refineries, pipelines, service stations and vehicle assembly plants has been designed and optimized for petroleum fuels.

On the other hand, petroleum fuels have certain drawbacks. Emissions of reactive hydrocarbons, carbon monoxide and oxides of nitrogen from gasoline and diesel vehicles contribute significantly to smog and other air pollution that plague most large American cities. Carbon dioxide emissions from petroleum fuel combustion add to the atmospheric buildup of greenhouse gases that cause global warming. The United States consumes far more oil than it can produce domestically, leading to concerns about our energy and national security.

There are several alternatives to nonpetroleum fuels such as methanol, ethanol, natural gas, propane, electricity and hydrogen that could reduce vehicle emissions of conventional and greenhouse pollutants and could be produced from domestic feedstocks. These fuels are all discussed in this report.

The final version of the Clean Air Act stopped short of mandating the sale or use of alternative fuels, but the Act includes several programs that require cleaner fuels and opens the fuel market to nonpetroleum gasoline additives. These include provisions that force modifications in gasoline composition and establish more stringent emission standards for vehicles in certain polluted areas. There are several major fuel-related provisions of the 1990 Clean Air Act, but the two most important to gasoline composition are the oxygenated fuel and reformulated gasoline programs.

The oxygenated fuels program affects 39 metropolitan areas that have high levels of carbon monoxide pollution. Beginning in November 1992, gasoline sold in the winter in these areas contained a minimum of 2.7 percent oxygen. The oxygen helps vehicles burn fuel more completely and this program is expected to reduce vehicle carbon monoxide emissions by 15 to 20 percent.

Fuel additives will supply the extra oxygen for these oxygenated gasolines. The most likely additives are ethanol and methyl tertiary butyl ether or MTBE, a methanol derivative. These additives will be used in about a third of the nation's gasoline, displacing 100,000 to 200,000 barrels per day of oil.

This program is specifically designed to combat carbon monoxide which is a colorless, odorless, poisonous gas. A product of incomplete burning of hydrocarbon-based fuels, carbon monoxide consists of a carbon atom and an oxygen atom linked together.

In 1990, 42 urban areas in the United States exceeded the Environmental Protection Agency's National Ambient Air Quality Standard for carbon monoxide. The oxy-fuel program is clearly working for the approximately 22 million people who live in these areas. In the first year of the program there was a 95 percent reduction in the number of days exceeding the health standard. Additional reductions have been reported by the EPA each year since.

The other major type of pollution addressed by alternative fuels and reformulated gasoline is ozone. Ozone in the upper atmosphere the "ozone layer" occurs naturally and protects life on earth by filtering out ultraviolet radiation from the sun. But ozone at ground level is a noxious pollutant. It is the major component of smog and presents this country's most intractable urban air quality problem.

Unhealthy ozone levels are a problem across the United States, with nearly 100 cities exceeding the EPA's National Ambient Air Quality Standard. The standard is based on the highest ozone exposure sensitive persons can tolerate. Nine cities, home to 57 million people, are considered "severely" polluted, experiencing peak ozone levels that exceed the standard by 50 percent or more.

The reformulated gasoline requirement applies to gasoline sold year-round in the nine metropolitan areas with the most severe ozone pollution. Beginning in 1995, reformulated gasoline specifications include a minimum oxygen content of two percent and a maximum one percent benzene content. Heavy metal additives are prohibited. Overall emission performance standards for reformulated gasoline call for at least 15 percent hydrocarbon and toxic emission reductions by 1995 and at least 20 to 25 percent reductions of hydrocarbons and toxic emissions beginning in the year 2000.

In addition to the use of oxygenates to boost fuel oxygen content, refineries will have to restrict or delete certain high-volatility compounds, aromatics, olefins and sulfur from gasoline.

The base requirement will reformulate 22 percent of the country's gasoline supply and displace between 100,000 and 350,000 barrels of oil per day. However, the Clean Air Act permits other polluted cities up to 87 across the country to voluntarily join, or "opt-into," the program which could result in reformulating more than half of the nation's gasoline.

The oxygenated fuels program and the reformulated gasoline program are aimed at cleaning up gasoline rather than literally replacing it. Alcohols and their ether derivatives will be the alternative fuels used in these programs because they increase the oxygen content and are easily mixed with gasoline, requiring no modifications to motor vehicles or the petroleum infrastructure. Both the Clean Air Act and the Energy Policy Act also address the opportunity for directly substituting petroleum with alternative fuels.

The Clean Air Act Amendments of 1990 created a Clean Fleets Program to introduce clean fuel vehicles nationwide. In model-year 1996, automobile manufacturers were required to produce 150,000 clean-fueled cars and light trucks per year under a California pilot program. For model years 1999 and thereafter, manufacturers must produce 300,000 clean fuel vehicles each year.

Beginning with 1998 models, fleets with ten or more vehicles capable of being centrally refueled in the 22 smoggiest cities the serious, severe and extreme ozone nonattainment areas plus Denver, Colorado for carbon monoxide nonattainment began to buy clean fuel vehicles. Marginal and moderate ozone nonattainment areas are not required to participate, but may elect to do so.

Beginning in the model year 1998, 30 percent of new passenger cars and most categories of light trucks and vans up to 8,500 pounds bought for these fleets must be clean fuel vehicles. The percentage rises to 50 percent of purchased vehicles in the model year 1999 and 70 percent in the year 2000 and beyond.

The Act defines clean alternative fuels as methanol, ethanol, other alcohols, reformulated gasoline, reformulated diesel for trucks only natural gas, liquefied petroleum gas or propane, hydrogen or electricity. Vehicles can be flexible-fuel or dual-fuel, but if so, must use clean fuel within the nonattainment areas.

The Energy Policy Act of 1992 provides federal mandates for alternative fuel vehicles. The primary aim of the Act is to reduce the United States' dependence on crude oil imports.

Source: U.S. Department of Energy, 1995

This legislation defines alternative fuel as natural gas, propane, alcohol methanol, ethanol and higher alcohols blends of alcohols with gasoline or other fuels containing 85 percent or more alcohol by volume, hydrogen, fuels derived from biomass and liquid fuels derived from coal and electricity. A fleet is defined as at least 20 vehicles that can be centrally fueled, being operated in a metropolitan area with a population of 250,000 or more based on 1980 Census and controlled by an entity that owns at least 50 such vehicles in the United States.

Private-sector companies that make alternative fuels, such as natural gas companies or electric utilities, are required to introduce alternative fuel vehicles into their fleets as follows:

The minimum federal fleet requirements for light-duty alternative fuel vehicles are as follows:

Purchases of light-duty vehicles by state governments are required to be alternative fuel vehicles in the following amounts:

There are currently 12 million vehicles in 91,000 fleets of ten or more in the United States. Fleets are growing at a rate of 1.6 percent annually, while the number of fleet vehicles is growing at a rate of 3.2 percent.

Most of these fleets are under 500 vehicles. The incremental cost of a light-duty truck or van fueled with natural gas over a conventionally-fueled vehicle is $2,500, so there is no economic incentive to convert. The economic attractiveness of conversion to a natural gas vehicle depends on rapid payback through fuel cost savings. In response to federal and state legislation, 38,500 natural gas vehicle fleets mostly small will be mandated for conversion by 2000. A total of 861,000 natural gas vehicles are projected to be purchased between 1995 and 2000 to meet these mandates.

The Clinton Administration has expressed a desire to accelerate the use of alternative fuels as evidenced by an Executive Order signed by President Clinton on April 21, 1993, directing the federal government to increase the rate of conversion of the federal fleet beyond that required by the Act. The Order calls for federal government purchases of 7,500 alternative-fuel vehicles in 1993, 11,250 in 1994 and 15,000 in 1995. These purchases are 50 percent higher than those called for in the Act. The administration has expressed particular interest in utilizing more compressed natural gas as a motor fuel.

Major automobile manufacturers continue to examine a variety of alternative fuel vehicle options in an effort to provide vehicles to meet the fleet requirements of the Clean Air Act and the Energy Policy Act. The current generation of alternative fuel vehicles available to consumers is somewhat limited as the auto industry attempts to respond to what is at present a limited market demand while also engaging in research and development programs in anticipation of future demand.

Automakers have repeatedly indicated that their ability to manufacture reliable and clean-running automobiles that are also capable of high fuel mileage using existing technology is diminishing. As witnessed by their comments on the fuel volatility issue, the automakers need reduced volatility fuels to make their vehicles run cleaner and more efficiently. Generally, they are supportive of oxygenated fuels as a means of replacing volatile petroleum-based components. In fact, former General Motors Corporation Chairman Roger Smith announced in late 1989 that he recommended the use of oxygenated fuels in their 1990 model automobiles, which they are now doing. The automobile manufacturers have been particularly supportive in the development of reformulated gasoline, providing much needed technical support and testing. As reiterated in a January 1995 press conference, the American Automobile Manufacturers Association stated:

"America's car companies Chrysler, Ford and General Motors support the reformulated gasoline program for three reasons. First, it reduces vehicle emissions for all cars, not just new ones. Second, it doesn't impact the personal mobility of consumers, choice of vehicles or convenience of operation. And third, it is a cost-effective way to further reduce mobile source emissions. This program demonstrates that clean air can be achieved with simple, cost-effective solutions that protect consumers' freedom of mobility."

All major manufacturers honor warranties for these EPA approved fuels containing oxygenates. An Appendix of automobile owner's manual oxygenated fuel recommendations can be found starting on page 35.