Natural Gas (CNG) Vehicle Glossary
Alternative Fuel Vehicle (AFV) - A vehicle with an engine designed to run on a fuel other than gasoline or diesel.
Bi-Fuel Natural Gas Vehicle - A vehicle with an engine capable of running on either natural gas (CNG) and gasoline or CNG and diesel.
CNG Storage Tanks or Cylinders - All storage tanks for vehicles are DOT certified and are most likely the strongest component within a vehicle due to strict manufacturing processes and mandated testing requirements. At present there are four basic types of CNG vehicle tanks. Type 1 cylinders are made completely of steel and are heavy, but less expensive than the other options. Type 2 cylinders are made of a thin steel liner wrapped in steel wire or an aluminum liner with carbon fiberglass composite wrapped around the middle of the tank so that both the liner and the composite each take 50% of the stress created by the internal pressurization. Type 3 is a similar concept except that the composite is wrapped around the whole tank so that the metal aluminum lining only bears a small portion of the burden. Type 4 cylinders can be the most expensive type of compressed natural gas cylinder but are also the lightest, with a gas tight interior lining and a fully wrapped composite carbon fiber exterior.
Compressed Natural Gas (CNG) -
Basically this is the same natural gas supplied by a regional gas utility that is piped to homes and buildings throughout America and used for heating homes and businesses. CNG is the same natural gas that is highly compressed and stored in high pressure storage tanks.
Dedicated NGV - A vehicle that can be fueled only by natural gas.
Diesel Gallon Equivalent (DGE) - A unit for measuring compressed natural gas (CNG) compared to one (1) gallon of diesel. One gallon of diesel is equivalent to approximately 143.94 cubic feet of natural gas.
Direct Use - Direct use involves burning natural gas directly at end-use applications such as furnaces, water heaters and other natural gas appliances or vehicles. This is as opposed to burning natural gas for electric generation which would then be used to power the same appliances or electric vehicles in a less efficient manner due to energy losses incurred during generation and transportation.
Dual-fuel - These vehicles are traditionally limited to heavy-duty applications, have fuel systems that run on natural gas (CNG), and use diesel fuel for ignition assistance. There are also duel fuel applications where the engine runs on a mixture of both diesel and CNG.
Gasoline Gallon Equivalent (GGE) - A unit for measuring compressed natural gas (CNG) compared to one (1) gallon of gasoline. One gallon of gasoline is equivalent to approximately 126.67 cubic feet of natural gas. CNG sold at filling stations is priced in dollars per GGE.
Home or Business CNG Fueling Appliance - A natural gas (CNG) fueling component that contains both compressor and fueling equipment which is sized for residential or business time fill use. Fast fill systems are available for businesses and require at least one CNG storage tank.
Natural Gas Vehicle (NGV) - A vehicle powered only by compressed natural gas.
Octane Rating - Natural gas (CNG) has a GGE octane rating of 130 and in America gasoline begins with regular at approximately 87 up to 97 octane for premium with 10%
OEM - Original Equipment Manufacturer
Public Fueling Station - Refers to a CNG fueling station that is accessible to the general public. Normally these stations are quick fill only.
Quick Fill - Refers to the process of fueling a vehicle with natural gas (CNG) in approximately the same time it would take to fuel the same vehicle with liquid fuels such as gasoline or diesel. All quick fill systems require storage tanks sized proportionally to the expected number of quick fill cycles during a given time frame.
Time Fill - A method of fueling a vehicle with natural gas (CNG) over an extended period of time, usually six to ten hours. The installation and equipment costs of a time fill system is lower than a quick fill system since a storage tank is not required.
Vehicle Conversion - Retrofitting a vehicle engine to run on only natural gas (CNG) or gasoline/CNG or diesel/CNG which is then defined as a bi-fuel vehicle.
Vehicle Refueling Appliance - A natural gas (CNG) fueling component that contains both compressor and fueling equipment. This term is normally used for the small CNG fueling systems. Some manufacturers have their equipment certified as natural gas appliances (gas furnaces, water heaters, clothes dryers, etc.) and some do not.