NATURAL GAS FOR CARS AND TRUCKS: OPTIONS AND CHALLENGES - Natural Gas-powered Cars and Trucks: Options and Issues - page 12

$2.69. 56 An extensive network of natural gas pipelines throughout the United
States provides a ready source of gas in most communities. The most difficult
step is finding an economical way to transfer that gas to facilities where it can
be pressurized as CNG and distributed commercially.
Stations can offer three ways to fill up a vehicle tank: fast-fill, time-fill, and
combination fill (using both fast- and time-fill). Fast-fill draws gas from the gas
utility line, filters it with a dryer to remove water and humidity, compresses it,
and then stores it in a tank from which it is dispensed. Most retail and some
fleet operations use this process, which requires only a few minutes to fill a 20-
gallon-equivalent tank. With time-fill, the CNG is provided straight from utility
gas line to the compressor. Since there is no storage tank to draw from, time-
fill's speed depends on the size of the compressor; it could take a few minutes
or many hours. An advantage to a slower fill is that the tank is filled more
thoroughly than with fast-fill. 57 Time-fill is usually a slower refueling option
and is often used by delivery trucks and buses refueling overnight at a central
garage or by car owners at home.
There are 772 public CNG service stations throughout the country
( Figure 4 ), and another 127 are planned. Car owners also have the option of
refueling vehicles at home. A home refueling unit, including installation, can
cost about $5,000. 58

Source: CRS map developed using DOE data, http://www.afdc.energy.gov/

fuels/natural_gas_locations.html.

Figure 4. CNG Refueling Stations. (Open in 2014)