U.S. ENVIRONMENTAL PROTECTION AGENCY EPA 400-F-92-015

OFFICE OF MOBILE SOURCES

FACT SHEET OMS-13

August, 1994

Vehicle Fuels and the 1990 Clean Air Act

Vehicle Fuels and Clean Air

Gasoline and diesel fuel are both produced from crude oil, that is, petroleum. Together, gasoline

and diesel fuel power 99 percent of this country’s motor vehicle fleet.

Past efforts to reduce vehicle emissions took petroleum fuels as a given and focused on the development of sophisticated engine and vehicle emission control systems involving catalytic converters,

on-board computers, and other hardware. It is becoming apparent, however, that fuel composition

and type are also critical factors in the clean vehicle equation.

The Clean Air Act of 1990 explicitly recognizes that changes in fuels as well as in vehicle technology

must play a role in reducing air pollution from motor vehicles.

Why the Interest in New Fuels?

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 important, our country’s vast transportation infrastructure (refineries, pipelines, service stations, vehicle assembly plants, etc.) 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

the air pollution that plagues most large American cities. Carbon dioxide emissions from petroleum

fuel combustion add to the atmospheric buildup of greenhouse gases and the potential for global

warming. The United States consumes far more oil than it can produce domestically, leading to

concerns over our energy and national security.

There are several alternative (i.e., 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. Unfortunately, to varying

degrees, a transition to one or more of these fuels could decrease vehicle range and increase the

overall cost of the U.S. transportation system, particularly during the transition when infrastructure

modifications would be necessary.
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Fuels and the 1990 Clean Air Act

Clean Fuel Provisions of the Clean Air Act of l990

The Clean Air Act stopped short of mandating the sale or use of alternative fuels. But the Act

includes several programs that will require cleaner fuels and will open up the fuel market to

nonpetroleum gasoline additives. These include provisions that force modifications in gasoline

composition and that establish more stringent emission standards for vehicles in certain polluted

areas. There are five major fuel-related provisions of the 1990 Clean Air Act:

• Oxygenated Fuels

The oxygenated fuels provision affects 31 metropolitan areas that have high levels of carbon

monoxide pollution (see chart).Since November 1992, gasoline sold in the winter in these

areas must contain a minimum of 2.7 percent oxygen. The oxygen helps vehicles burn fuel

more completely. this program has reduced vehicle carbon monoxide emissions by 15 to 20

percent.

Fuel additives supply the extra oxygen for oxygenated gasolines. The most common additives

are ethanol and methyl tertiary butyl ether (MTBE), a methanol derivative. These additives are

being used in about a third of the nation’s gasoline, displacing 100,000 to 200,000 barrels per

day of oil. The oxygen additive added a few cents per gallon to the cost of gasoline.

• Reformulated Gasoline

The reformulated gasoline requirement applies to gasoline sold year-round in the nine metropolitan areas with the most severe ozone pollution (see chart). Beginning in 1995, reformulated

gasoline specifications include a minimum oxygen content of 2 percent and a maximum 1 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 oxygenatesto boost fuel oxygen content, it is expected that refineries

will have to restrict or delete certain high-volatility compounds, aromatics, olefins, and sulfur

from gasoline.

The nine-city base requirement will reformulate 22 percent of the country’s gasoline supply and

displace between 100,000 and 350,000 barrels per day of oil. However, the Clean Air Act

permits other polluted cities (up to 87 across the country) to voluntarily join the program, which

could result in reformulating more than half of the nation’s gasoline. Again, the price of gasoline

is projected to rise by a few cents per gallon.

• California Pilot Program

This program sets lower hydrocarbon emission standards (relative to cars in the general U.S.

market) for a set number of new passenger cars and light trucks sold in California beginning in
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Fuels and the 1990 Clean Air Act

1996. The standards drop still lower beginning in 2001, when a new nitrogen oxide standard

also takes effect. The sales requirement is 150,000 vehicles per year in 1996 through 1998

and 300,000 vehicles per year thereafter.

It appears that reformulated gasoline will likely be the fuel of choice to meet the California

standards (possibly combined with some engine modifications and additional emission control

hardware such as an electrically heated catalytic converter). Alcoholflexible fuel vehicles

(which can operate on alcohol or gasoline or any blend of the two) are another possibility.

California must mandate availability of any fuel necessary to operate clean-fueled vehicles.

Other states may adopt California’s vehicle standards.

• Clean-Fuel Fleet Vehicle Program

This provision applies to fleets in 23 metropolitan areas around the country that have high ozone

and/or carbon monoxide pollution (see chart). Like the California Pilot Program, the fleet

program requires vehicles that are cleaner than those for sale in the general U.S. market. A

portion of new cars, light trucks, and medium-duty trucks purchased by fleets will need to meet

the lower hydrocarbon and nitrogen oxide emission standards beginning in 1998. Individual

states must ensure that appropriate fuels are available for clean-fueled fleet vehicles.

It is expected that vehicles operating on reformulated gasoline will be able to meet the lower

standards, though some fleets may consider fuels such as natural gas or propane which can

offer cost savings. All in all, this program will affect approximately 35,000 fleets and should

result in about one million clean-fueled vehicles by 2010.

• Transit Bus Provisions

The particulate matter emission standard for transit bus engines is progressively tightened in both

1993 and 1994. Although it is expected that redesigned diesel bus engines equipped with

catalysts will be able to meet these standards, some transit operators are expected to consider

alternative fuels such as methanol and natural gas.

Beginning in 1994, EPA must evaluate whether buses are continuing to emit low levels of

particulate matter in actual service. If not, EPA must establish a low-polluting fuels requirement

beginning in the late 1990s that would affect new transit buses in all cities with populations of

750,000 or more. This requirement could result in widespread substitution of alternative fuels

for diesel in the nation’s transit bus fleet.

For More Information:

The Office of Mobile Sources is the national center for research and policy on air

pollution from highway and off-highway motor vehicles and equipment. You

can write to us at the EPA National Vehicle and Fuel Emissions Laboratory,

2565 Plymouth Road, Ann Arbor, MI 48105. Our phone number is (313) 668-4333.