What
Types of Vehicles Run on Compressed Natural
Gas?
According
to the Natural Gas Vehicle Coalition (NGVC),
as of 2005 there are 130,000 light- and
heavy-duty compressed natural gas (CNG) and
liquefied natural gas (LNG) vehicles in the
United States and 5 million worldwide.
Dedicated
natural gas vehicles (NGVs) are designed to
run only on natural gas; bi-fuel NGVs have
two separate fueling systems that enable the
vehicle to use either natural gas or a
conventional fuel (gasoline or diesel). In
general, dedicated NGVs demonstrate better
performance and have lower emissions than
bi-fuel vehicles because their engines are
optimized to run on natural gas. In
addition, the vehicle does not have to carry
two types of fuel, thereby increasing cargo
capacity and reducing weight.
There
are a few light-duty NGVs still available,
but if you want a specific type of vehicle,
you may want to consider retrofitting a
vehicle to an NGV by using an aftermarket
conversion system. Heavy-duty NGVs are also
available as trucks, buses, and shuttles.
Approximately one of every five new transit
buses in the United States is powered by
natural gas.
As
a new twist, tests are being conducted using
natural gas vehicles that are fueled with a
blend of compressed natural gas and
hydrogen.
Vehicle
Availability
This
model year, auto manufacturers are producing
fewer models than in years past. In order to
get more vehicle options, you may choose to
retrofit your own vehicle.
Fuel
Availability
CNG
fueling stations are located in most major
cities and in many rural areas. Public LNG
stations are limited and used mostly by
fleets and heavy-duty trucks. LNG is
available through suppliers of cryogenic
liquids.
Vehicle
Safety
Natural
gas vehicles are just as safe as today's
conventional gasoline and diesel vehicles.
They use pressurized tanks, which have been
designed to withstand severe impact, high
external temperatures, and environmental
exposure.
Adequate
training is required to operate and maintain
natural gas vehicles because they are
different than gasoline or diesel vehicles.
Training and certification of service
technicians is required.
Vehicle
Costs
In
general, a natural gas vehicle can be less
expensive to operate than a comparable
conventionally fueled vehicle depending on
natural gas prices. Natural gas can cost
less than gasoline and diesel (per energy
equivalent gallon); however, local utility
rates can vary.
Purchase
prices for natural gas vehicles are somewhat
higher than for similar conventional
vehicles. The auto manufacturers' typical
price premium for a light-duty CNG vehicle
can be $1,500 to $6,000, and for heavy-duty
trucks and buses it is in the range of
$30,000 to $50,000. Federal and other
incentives can help defray some of the
increase in vehicle acquisition costs. In
addition, fleets may need to purchase
service and diagnostic equipment if access
to commercial CNG/LNG vehicle maintenance
facilities is not available.
Retrofitting
a conventional vehicle so it can run on CNG
may cost $2,000 to $4,000 per vehicle.
Maintenance
Considerations
High-pressure
tanks that hold CNG require periodic
inspection and certification by a licensed
inspector.
Fleets
doing on-site maintenance may need to
upgrade their facilities to accomodate NGVs.
Costs for upgrading maintenance facilities
will depend on the number of modifications
required.
Some
natural gas vehicle manufacturers now
recommend oil changes at intervals twice as
long as similar gasoline or diesel models
(10,000-12,000 miles). Refer to the vehicle
owner's manual or consult the manufacturer
to determine proper maintenance intervals.
Benefits
-
Compared
with vehicles fueled by conventional
diesel and gasoline, NGVs can produce
significantly lower amounts of harmful
emissions such as nitrogen oxides,
particulate matter, and toxic and
carcinogenic pollutants. NGVs can also
reduce emissions of carbon dioxide, the
primary greenhouse gas. For details, see
the following publications from the U.S.
Environmental Protection Agency:
-
The
cost of a gasoline-gallon equivalent of
CNG can be favorable compared to that of
gasoline, but varies depending on local
natural gas prices.
-
Natural
gas is mostly domestically produced. In
2004, net imports of natural gas was
approximately 15% of the total used,
with almost all the imports coming from
Canada.
-
Some
natural gas vehicle owners report
service lives 2 to 3 years longer than
gasoline or diesel vehicles and extended
time between required maintenance.
Performance
-
Vehicle
range for CNG and LNG vehicles generally
is less than that of comparable
gasoline- and diesel-fueled vehicles
because of the lower energy content of
natural gas. Extra storage tanks can
increase range, but the additional
weight may displace some payload
capacity.
-
NGV
horsepower, acceleration, and cruise
speed are comparable with those of an
equivalent conventionally fueled
vehicle.
-
Depending
on the number of cylinders and their
locations, some payload capacity may be
compromised with NGVs.
-
Bi-fuel
NGVs offer a driving range similar to
that of gasoline vehicles.
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