Civil Engineering Reference
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refueling infrastructure may be installed. In some cases, government subsidies
have been required to make CNG competitive with diesel fuel. In September
2014, for example, the brewer Anheuser-Busch announced that it would
replace 66 heavy-duty delivery trucks in Houston with CNG-powered vehicles
after the Texas Commission on Environmental Quality approved a $45,000
grant for each vehicle.
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There are about 150,000 CNG vehicles on the road today in the United
States. About 88,000 are cars, SUVs, and vans, and the rest are commercial
vehicles, refuse trucks, and buses.
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Among passenger vehicles, and in
addition to the Honda Civic natural gas sedan and the Chevrolet Impala sedan,
automakers offer bifuel Chevrolet Silverado and Sierra pickup trucks and a
Chrysler Dodge Ram 2500 Dual Cab pickup truck. General Motors also offers
Express and Savana cargo and passenger vans with dedicated CNG engines.
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Further, several companies offer natural gas conversions of new vehicles.
Liquefied Natural Gas
LNG is produced when natural gas is cooled to -260 degrees Fahrenheit,
turning it into a liquid fuel that takes up 1/600 of the volume of the fuel in a
gaseous state. Long-haul trucks are a target market for use of LNG because of
the fuel's price advantage and environmental benefits over diesel fuel.
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It is
preferred over CNG for long-haul trucking because it requires only 30% of the
space to store the same amount of energy
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and has a higher energy density per
unit of volume.
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Range is also important, as long-haul truck drivers seek to
reduce down-time in refueling. According to trucking company J. B. Hunt
Transport Services,
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a diesel tractor with:
a 100-gallon diesel tank has a range of 640 miles,
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two 100-gallon LNG tanks (110 DGE) has a range of 605 miles,
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and
four 25-gallon CNG tanks (100 DGE) has a range of 467 miles.
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When a truck engine is started, it warms the LNG, converting it into a
compressed gas. While about 80% of an LNG truck engine is similar to a
diesel truck engine,
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LNG-related components add about $50,000 to the price
of a truck that might otherwise sell for $150,000.
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According to truck
manufacturer Freightliner, an LNG-fueled truck driven 50,000 miles per year
could save $85,000 in annual fuel costs, recouping the additional capital cost
of the vehicle in seven months.
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