NGV Vehicle Types
Natural Gas Vehicles (NGVs) are developed based on the same internal combustion engines as gasoline and diesel vehicles and the performance and fuel economy are comparable with those of equivalent conventional vehicles. There are three types of NGV engine applications:
- Dedicated – Vehicle application using only natural gas
- Bi-fuel – Light- or medium-duty application which uses natural gas or gasoline interchangeably
- Dual fuel – Heavy-duty application using a blend of natural gas and diesel simultaneously
Natural gas can also be stored on the vehicle in two different forms:
- Compressed Natural Gas (CNG) – Natural gas is compressed to 3,600 psig but remains in a gaseous state. The fuel density is less than gasoline or diesel but the vehicle fuel storage cylinder(s) are sized to have enough on board fuel to achieve the necessary driving range. There are a multiple vehicle types using CNG in the light-, medium-, and heavy-duty classifications.
- Liquefied Natural Gas (LNG) – Natural gas is refrigerated to –260 degrees F and is stored on the vehicle in a liquid state. This is generally only used in heavy-duty applications that need a greater range because the fuel occupies less space in liquid form. Most LNG vehicles operate like CNG vehicles because although the fuel is stored in liquid form it is then vaporized before being introduced to the engine.