Thanks for mentioning the Freightliner site. There's a calculator there that lets you figure out the cost of converting and running CNG versus gasoline or diesel. For long distance truckers, it looks like costs are recovered in a year, and they would enjoy 50% lower fuel costs after that.
http://freightlinergreen.com/calculator
There's a unit of measure called the Gallon Gasoline Equivalent, or GGE. It's the amount of CNG, or electricity, or any other fuel, that provides the same amount of energy as a gallon of gas. GGE helps you compare the cost of alternative fuels with the cost of a gallon of gas.
About 126 cubic feet of CNG has the equivalent energy of one gallon of gasoline. Compressed at 2400 psi, 126 cubic feet of CNG occupies 0.77 cubic feet, or about 5.6 gallons. To provide a practical driving range, a CNG tank has to be very large. That's not a problem on a large truck, but becomes an issue in a passenger car. The Honda Civic GX, for example, loses 2/3 of its trunk space to the fuel tank, and still has a range of only 225 miles.
CNG burns cleaner than petroleum fuels, so emissions controls can be simplified. Cleaner burning means more miles between oil changes, and less carbon buildup in the combustion chamber.
http://freightlinergreen.com/calculator
There's a unit of measure called the Gallon Gasoline Equivalent, or GGE. It's the amount of CNG, or electricity, or any other fuel, that provides the same amount of energy as a gallon of gas. GGE helps you compare the cost of alternative fuels with the cost of a gallon of gas.
About 126 cubic feet of CNG has the equivalent energy of one gallon of gasoline. Compressed at 2400 psi, 126 cubic feet of CNG occupies 0.77 cubic feet, or about 5.6 gallons. To provide a practical driving range, a CNG tank has to be very large. That's not a problem on a large truck, but becomes an issue in a passenger car. The Honda Civic GX, for example, loses 2/3 of its trunk space to the fuel tank, and still has a range of only 225 miles.
CNG burns cleaner than petroleum fuels, so emissions controls can be simplified. Cleaner burning means more miles between oil changes, and less carbon buildup in the combustion chamber.