CNG Basics

What you need to know

What is CNG?

Natural gas vehicle fuel is the same gas that heats homes and powers industries. Because it has a lower energy content by volume than diesel or gasoline, it must be compressed (CNG) or liquefied (LNG) to operate vehicles efficiently.

What's the difference between CNG and LNG?

CNG is more commonly used for transportation because it is typically less expensive than LNG and more widely available. LNG is suitable for remote or isolated locations where there is no pipeline infrastructure. More about LNG.

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How does CNG compare?

A CNG engine works just like any other internal combustion engine.

Pull up to 32,287 kg (80,000 lb) GVW

Cover up to 1,700 km (1,050 miles)

Match hp and torque of diesel

Natural gas vehicles match the power and performance of diesel

  • Ratings of up to 400 hp and 1,750 ft-lb torque
  • Dual-fuel models increase GVW capacity and driving range
  • Overall vehicle maintenance similar to diesel
  • Engine sizes ranging up to just under 12 L
  • A CNG engine works just like any other internal combustion engine

Important differences:

  • Drivers report preference for quieter, clean-smelling operation
  • Max torque is reached at a higher RPM with CNG
  • NG exhaust can be hotter than diesel: for curbside collection, exhaust upward, not below the truck
  • Compressors and refuelling equipment require filter changes and draining to avoid oil carry-over into the engine
  • No emissions equipment to service and maintain

Refuelling Basics

Natural gas comes to filling stations via pipeline. The gas passes through a compressor to increase the pressure before being dispensed. Vehicles are fuelled through a nozzle similar to that used for gasoline or diesel, and the compressed fuel is stored on-board in durable fuel tanks. Fleet vehicles can be refuelled using fast fill, time fill or combination systems.

Fast Fill Stations: On-demand, comparable to liquid fuels

diagram of CNG fast fill system

Time fill stations: cost-effective, refuel overnight

diagram of CNG overnight fill stations

Combination systems: maximize capacity day and night

diagram of combination CNG fill system