v>EPA
United States
Environmental Protection
Agency
Transportation and Air Quality
Transportation and Regional
Programs Division
EPA420-F-00-038
March 2002
www.epa.gov
g\)CCESS STOffy
Clean Alternative
Fuels:
Liquefied Natural Gas
One in a series of fact sheets
For decades, natural gas has provided clean power to thousands of
households and businesses nationwide. Today, more than 1,000
vehicles traveling U.S. roads are powered by natural gas that is cooled to
a liquid—liquefied natural gas (LNG). LNG results when natural gas is cooled to
temperatures of 260 degrees below zero, thus producing a viable vehicle fuel
used mainly in heavy-duty trucks and buses.
In its quest to be an
environmental leader, Waste
Management, Inc., began
using LNG in 1998 to fuel
six of its waste haulers in
Pittsburgh, Pennsylvania.
Since that time, driver
response has been very posi-
tive, in part because LNG
generates less noise than
diesel-powered engines.
In California, the compa-
ny is currently purchasing
new vehicles and converting
existing vehicle engines to
run on LNG. Soon, more
than 100 of the company's
heavy-duty trucks will use
both compressed and lique-
fied natural gas.
In addition to helping
the environment, the com-
pany's use of LNG is bene-
fiting its bottom line. By
using cleaner fuels such as
LNG, the company has a
competitive advantage when
bidding on waste hauling
contracts in cities trying to
control air emissions.
For more information on
Waste Management's use of
LNG, contact Paul Gannon
at (813) 909-0163.
LNG is odorless, colorless, noncorrosive,
and nontoxic. When extracted from
underground reserves, natural gas is com-
posed of approximately 90 percent
methane. During the liquefaction process,
oxygen, carbon dioxide, sulfur com-
pounds, and water are removed, purifying
the fuel and increasing its methane con-
tent to almost 100 percent. As a result,
LNG-fueled vehicles can offer significant
emissions benefits compared with older
diesel-powered vehicles, and can signifi-
cantly reduce carbon monoxide and par-
ticulate emissions as well as nitrogen oxide
emissions.
AVAILABILITY
To date, LNG vehicles have primarily
been used by fleet managers. Therefore,
most LNG refueling stations are located at
heavy-duty vehicle fleet operations not
open to the public. This is due in part to
the various safety issues discussed later. In
conjunction with plans to expand LNG
use in long-haul trucking in the West,
efforts are under way to improve access to
LNG fueling stations in that region. For
example, California expects to fund the
development of public-access facilities.
Such a program is aimed at helping heavy-
duty trucks switch to natural gas.
LNG's complex onboard storage system
does not make it a viable fuel for light-
EMISSIONS
CHARACTERS

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Actual emissions will vary with
engine design; these numbers reflect
the potential reductions offered by
LNG relative to diesel.
•	Production of half particulate mat-
ter of average diesel vehicles.
•	Can significantly reduce carbon
monoxide emissions.
•	Reductions of nitrogen oxide and
volatile organic hydrocarbon emis-
sions by 50 percent or more.
•	Potential reductions in carbon
dioxide emissions of 25 percent
depending on the source of the nat-
ural gas.
•	Drastic reductions in toxic and car-
cinogenic pollutants.
•	Increase in methane emissions.
•	Estimates based on LNG's inherently
"cleaner" chemical properties with an engine
that takes full advantage of these fuel proper-
ties.

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duty vehicles. It is, however, replac-
ing diesel in many heavy-duty trucks
and buses and many new gas-fueled
locomotives. For example, some trash
trucks in San Diego and some long-
haul trucks in Los Angeles and Sacra-
mento use LNG fuel. In addition,
the number of LNG-fueled transit
buses is expanding rapidly as many
cities try to reduce air pollution lev-
els. Bus fleets in Orange County,
California, and Phoenix, Arizona, are
fueled entirely by LNG.
AFFORDABILITY
Depending on the quantity of
vehicles purchased and the equip-
ment used, LNG heavy-duty trucks
or buses can cost an additional
$30,000 to $50,000. Industry
experts expect these costs to drop as
market development and vehicle pro-
duction rises. Fuel dispensing and
fuel storage required for LNG typi-
cally costs $15,000 to $22,000 per
vehicle. In addition, LNGs price is
highly dependent on geographic
location, purity of feedstock, trans-
portation costs, and quantity of fuel
purchased, but LNG's cost per mile
is generally less than or equal to the
price of diesel.
PERFORMANCE
There are no discernible differences
in LNG vehicle performance, opera-
tion, and utility when compared with
diesel. The high ignition quality of
LNG is similar to that of diesel, pro-
viding for similar durability and
engine life overall.
SAFETY
A LNG vehicle parked indoors and
unmoved for a week or more will
vent a flammable gas mixture that
could catch fire in the vicinity of an
ignition source. To address this safety
issue, LNG use should be restricted
to frequently driven fleet vehicles or
to vehicles stored outdoors. Only
trained personnel should service the
vehicles.
In addition, refueling vehicles with
LNG requires training because of the
fuel's ultra low temperature. It can
cause frostbite if it contacts skin.
Since LNG is almost 100 percent
methane—a greenhouse gas—it can
also contribute to global climate
change if accidentally released into
the air. Methane is slightly soluble in
water and, under certain environ-
mental conditions (anaerobic), it
does not bio-degrade. If excess
amounts accumulate, the gas can
bubble from the water, possibly cre-
ating a risk of fire or explosion.
MAINTENANCE
LNG's cleaner burning characteristics
can result in longer engine life and
reduced maintenance costs. Using
LNG eliminates the need for period-
ic tank inspections. In addition,
some maintenance savings are antici-
pated for vehicles using LNG when
compared with gasoline-powered
vehicles because of the reduced fre-
quency of oil changes. Because of the
fuel's below freezing temperatures,
only trained personnel should main-
tain LNG vehicles.
For More Information
EPA Alternative Fuels Web Site
www.epa.gov/ otaq/consumer/
fuels/altfuels/altfuels.htm
Natural Gas Vehicle Coalition
1100 Wilson Boulevard
Suite 850
Arlington, VA 22209
Phone: 703 527-3022
Fax: 703 527-3025
Web site: www.ngvc.org
Alternative Fuel Refueling
Station Locator
Web site: afdcmap.nrel.gov/nrel
Alternative Fuels Data Center
Web site: www.afdc.nrel.gov
National Alternative Fuels
Hotline
Phone: 800 423-1 DOE
Printed on paper that contains at least 30 percent postconsumer fiber.

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