Size and Design

How much fuel a fleet needs over what timeframe determines the size of a natural gas refueling station. A fleet owner needs to accurately project fill time and quantity of fuel required daily. Future growth of the natural gas fleet is also an important factor in station design planning. Equipment and service suppliers and gas utilities can help determine the size and type of station needed.

Enbridge Gas Distribution CNG dump truck refueling

Compressed natural gas (CNG) stations are described by their flow rate in standard cubic feet per minute. CNG vehicles are filled to a particular gas density. To ensure that the vehicle is filled to the rated capacity (i.e., 3,600 pounds per square inch at a private station), the station equipment must adjust the dispensed pressure to allow for changes in the temperature of the natural gas. The amount of gas dispensed in standard cubic feet per minute needs to remain constant regardless of temperature.

To identify the required fuel output for a CNG station:

  1. Identify vehicles to be fueled by CNG.
  2. Record the fuel consumption for each type of vehicle. Use the average fuel consumption per vehicle. Using the maximum fuel consumption may oversize the station.
  3. Determine the highest demand fuel window in each 24-hour period.

To calculate the total standard cubic feet of natural gas (SCF) required daily, convert diesel or gasoline litres to cubic feet of natural gas:

Daily Station Volume

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OR

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* Note that gasoline has a lower energy density content than diesel. To convert from gasoline litres to standard cubic feet, multiply gasoline litres by 33.

Liquefied natural gas (LNG) vehicles are filled by volume similar to diesel or gasoline vehicles.

Engineering consultants can help with station design, detailed technical requirements, site assessment, equipment specifications, and cost estimates. It takes about four to six months to install a CNG or LNG refueling station. This estimate takes into account the time it takes to order and deliver equipment, as well as design, engineering, installation, and approval time.