24-01-2013, 01:00 PM
Clean Alternative Fuels: Compressed Natural Gas
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INTRODUCTION
Natural gas is one of the most widely used forms of energy today.
It is commonly used to heat and cool homes and businesses
nationwide. In addition, more than 85,000 compressed natural
gas (CNG) vehicles, including one out of every five transit buses, are operating
sucessfully today. CNG’s popularity stems, in part, from its clean-burning properties.
In many cases, CNG vehicles generate fewer exhaust and greenhouse
gas emissions than their gasoline- or diesel-powered counterparts.
CNG is odorless, colorless, and tasteless.
It consists mostly of methane and is
drawn from gas wells or in conjunction
with crude oil production. CNG vehicles
store natural gas in high-pressure fuel
cylinders at 3,000 to 3,600 pounds per
square inch. An odorant is normally
added to CNG for safety reasons.
Two types of CNG fuel systems are on the
market: dedicated vehicles, which operate
exclusively on natural gas, and dual-fuel
vehicles, which can use both natural gas
and gasoline. Auto manufacturers offer a
variety of both dedicated and dual-fuel
CNG vehicles, including compacts,
trucks, vans, and buses.
The United States has vast natural gas
reserves distributed across the country
through extensive pipeline systems extending
from the wellhead to the end-user. As
a result, CNG is currently available at
approximately 1,300 refueling stations in
46 states, and this number continues to
grow.