U.S. ENVIRONMENTAL PROTECTION AGENCY   	EPA 4oo-F-92-oo8
          OFFICE OF MOBILE SOURCES
           Clean Fuels: An  Overview
What are Clean Fuels?
The most familiar transportation fuels in this country are gasoline and diesel
fuel, but any number of energy sources are capable of powering motor vehicles.
These include alcohols, electricity, natural gas, and propane.

Some vehicle fuels, because of physical or chemical properties, create less pollu-
tion than do today's gasolines. These are called "clean fuels."

Why Switch to Clean Fuels?
Cars operating on today's gasolines emit complex mixtures of compounds that
lead to the formation of ground-level ozone; many of these compounds are also
toxic.  A lot has been done to reduce automobile pollution, from development of
innovative emission control technologies to establishment of Inspection and
Maintenance programs. But each year sees more cars on the road, traveling
more miles, and the pollution control measures taken so far have not been suffi-
cient to solve the ozone problem in many large cities.

Clean fuels have a number of inherent properties that make them cleaner than
conventional gasoline.  In general, these fuels emit less hydrocarbons, and the
hydrocarbons they do emit are less reactive (slower to form ozone) and less toxic.
Emissions from electricity, natural gas, or alcohol-powered vehicles can be as
much as 90 percent lower in toxics and ozone-forming hydrocarbons than emis-
sions from vehicles fueled with conventional gasoline. New gasoline formula-
tions ("reformulated gasoline") are expected to reduce these emissions up to 25
percent over today's gasoline.

Use of clean fuels could also help slow atmospheric buildup of carbon dioxide, a
"greenhouse gas" that contributes to the potential for global warming. Combus-
tion of any carbon-based fuel produces carbon dioxide. But the overall impact of
a given fuel on global warming depends on how the fuel is made. In general,
fuels produced from biomass (crops, trees, etc.) and from natural gas result in
less carbon dioxide accumulation than fuels made from petroleum or coal.

Clean fuels have benefits that reach beyond their air quality advantages. New
fuels in the marketplace give  consumers new choices and could decrease  our
dependence on imported oil.
                                                      FACT SHEET OMS-6
                                                         August, 1994

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     Clean Fuels: an Overview
FUEL
ELECTRICITY
ETHANOL
METHANOL
NATURAL GAS
(METHANE)
PROPANE
REFORMULATED
GASOLINE
ADVANTAGES
• Potential for zero vehicle emissions
• Power plant emissions easier to control
• Can recharge at night when power demand
is low
• Excellent automotive fuel
• Very low emissions of ozone-forming
hydrocarbons and toxics
• Made from renewable sources
• Can be domestically produced
• Excellent automotive fuel
• Very low emissions of ozone-forming
hydrocarbons and toxics
• Can be made from a variety of feedstocks,
includina renewables
• Very low emissions of ozone-forming
hydrocarbons, toxics, and carbon
monoxide
• Can be made from a variety of feedstocks,
including renewables
• Excellent fuel, especially for fleet vehicles
• Cheaper than gasoline today
• Most widely available clean fuel today
• Somewhat lower emissions of ozone -
forming hydrocarbons and toxics
• Excellent fuel, especially for fleet vehicles
• Can be used in all cars without changing
vehicles or fuel distribution system.
• Somewhat lower emissions of ozone -
forming hydrocarbons, nitrogen oxides,
and toxics
DISADVANTAGES
• Current technology is limited
• Higher vehicle cost; lower
vehicle range, performance
• Less convenient refueling
• High fuel cost
• Somewhat lower vehicle range
• Fuel could initially be imported
• Somewhat lower vehicle range
• Higher vehicle cost
• Lower vehicle range
• Less convenient refueling
• Cost will rise with demand
• Limited supply
• No energy security or trade
balance benefits
• Somewhat higher fuel cost
• Few energy security or
trade balance benefits
•ELECTRICITY
 Battery-powered vehicles give off virtually no pollution and offer one of the best
 options for reducing motor vehicle emissions in polluted cities.  Power plants
 that produce electricity do pollute.  But these plants are often in rural areas
 where the emissions do not drive pollution levels above health standards. Also,
 efficient emission controls can be installed and maintained more easily on
 individual power plants than on millions of vehicles. The driving range of
 today's electric cars is limited by the amount of power the battery can provide.
 Current batteries take hours to recharge and the cost of electric vehicles  is
 high. Recent developments in electric vehicle technology show  much promise
 for the future.

•ETHANOL
 Ethanol ("grain alcohol") is the primary automotive fuel in Brazil, and ethanol/
 gasoline blends (known as "gasohol") have been used in the United States for
 many years. Pure ethanol fuel offers excellent performance, plus low hydrocar-
 bon and toxic emissions. It can be produced domestically from corn or other
 crops, as well as from cellulosic materials such as wood or paper wastes, poten-
 tially minimizing the accumulation of greenhouse gases (since these "renew-
 able" feedstocks draw carbon dioxide out of the atmosphere as they grow). With
 current technology and price structures, ethanol is more  expensive than gaso-
 line. New technologies offer the hope of significantly reduced costs.
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      Clean Fuels: an Overview
 • METHANOL
  Methanol ("wood alcohol"), like ethanol, is a high-performance liquid fuel that
  emits low levels of toxic and ozone-forming compounds. It can be produced at
  prices comparable to gasoline from natural gas and can also be produced from
  coal and wood. All major auto maufacturers have produced cars that run on
  "M85," a blend of 85 percent methanol and 15 percent gasoline. Cars that burn
  pure methanol (Ml00) offer much greater air quality and efficiency advantages.
  Many auto manufacturers have developed advanced Ml00 prototypes.  Metha-
  nol has long been the fuel of choice for race cars because of its superior perfor-
  mance and fire safety characteristics.

 •NATURAL GAS (METHANE)
  Natural gas is abundant and is widely used for home heating and industrial
  processes. It is easily transported through pipelines and costs about the same
  or slightly less than gasoline. Compressed natural gas (CNG) vehicles emit
  low levels of toxics and ozone-forming hydrocarbons.  But CNG fuel must be
  stored under pressure in heavy tanks, and the cost of accommodating these
  tanks must be considered.  There are significant tradeoffs for CNG vehicles
  among emissions, vehicle power, efficiency, and range; however, natural gas is
  already used in some fleet  vehicles and appears to have a bright future as a
  motor vehicle fuel.

 • PROPANE
  Propane, or liquefied petroleum gas, is a by-product of petroleum refining and
  natural gas production. It burns more cleanly than gasoline but is limited in
  supply. Propane-fueled vehicles are already common in many parts of the
  world.

 • REFORMULATED AND OXYGENATED GASOLINE
  The petroleum industry is  beginning to market gasoline formulations that emit
  less hydrocarbons, nitrogen oxides, carbon monoxide, and toxics than conven-
  tional gasoline.  These new gasolines can be introduced without major modifica-
  tion to existing vehicles or the fuel distribution system. The Clean Air  Act
  requires some gasoline modifications to reduce carbon monoxide emissions
  beginning in 1992 and use of reformulated gasoline in certain polluted  cities
  beginning in 1995.

 Are Clean Fuels Feasible?
 Clean-fueled vehicles are here today and widespread use in the near future is
 feasible. To enable the transition, technologies must be refined so vehicles can
 achieve optimum performance and emissions characteristics. Consumers must
 accept the  new vehicles and fuels, and government and industry must cooperate
 to ensure their availability.  It will take a concerted effort by all sectors of society,
 but a switch to clean fuels may be the most viable way for many cities to attain
 clean and healthy air.
 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.

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