Frequently Asked Questions

What is natural gas?
Natural Gas Molecule

Natural gas is 90 percent methane and contains a mixture of hydrocarbons that is produced from gas wells or from crude petroleum production. It is clean burning, domestic and readily available for consumers.

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What is CNG?
CNG or compressed natural gas is natural gas that is highly compressed and stored in high-pressure storage containers. CNG is used extensively as a transportation fuel for automobiles, trucks and busses.

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What is LNG?
LNG or liquefied natural gas is natural gas that has been liquefied by reducing its temperature to
-260 degrees Fahrenheit at atmospheric pressure. LNG is mainly used as a transportation fuel in heavy-duty vehicle applications.

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Can natural gas be used in any vehicle?
No. There are vehicles that are made specifically to run on natural gas (dedicated) and others that are bi-fueled that can use natural gas or conventional fuels (like gasoline or diesel). The two types of natural gas that can be stored on a vehicle are compressed natural gas (CNG) and liquefied natural gas (LNG). However, many vehicles can be converted to run on natural gas. The conversion systems must be certified by the U.S. Environmental Protection Agency.  Vehicles that use natural gas are called natural gas vehicles (NGVs).

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What is a converted or conversion vehicle?
Dedicated CNG SystemWhen an original equipment manufacturer (OEM) vehicle designed to run on conventional gasoline is altered after market to run on an alternative fuel, like natural gas, or a combination of gasoline and alternative fuel, the vehicle is considered a conversion vehicle.  It can also be referred to as retrofitting a vehicle or a retrofitted vehicle. One of the most common conversions is altering vehicles to run on compressed natural gas (CNG). There are essentially two types of natural gas conversions: dedicated and bi-fuel. Dedicated vehicles operate exclusively on natural gas. Bi-fuel vehicles have separate fuel tanks for the gasoline and natural gas--an automatic fuel selection device selects the desired fuel.

All natural gas conversions must meet EPA standards. Converted vehicles operating in California must also meet California Air Resource Board (CARB) rules. Conversions should be performed  by qualified system retrofitters using EPA-/CARB-Certified systems from Small Volume Manufacturers (SVM).

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I want to convert my personal vehicle to operate on CNG. Is it possible?
Many late-model Ford, GM and a limited number of Chrysler vehicles can be converted to operate on CNG. First and foremost, the conversion system must be EPA and/or California Air Resources Board (CARB) - certified and compliant to avoid tampering violations as legislated through the Clean Air Act Amendments. Conversion systems should only be installed by a reputable company that is certified by the conversion system manufacturer. Also, check with the original vehicle manufacturer regarding warranty issues. Lastly, make sure you have access to public fueling or a home fueling appliance installed.

To see a list of certified conversion systems and their applicable vehicle models,
click here. This list was last updated in November 2013. More information is also available on the EPA website.

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Are natural gas vehicles available?
CNG Refuse Heavy-Duty TruckYes, there are light-, medium-, and heavy-duty natural gas vehicles available for purchase today.
Other natural gas vehicles are available through conversions or system retrofits by small volume manufacturers. Available natural gas vehicles include applications ranging from taxi fleets to transit and school buses to refuse haulers. According to NGVAmerica there are currently more than 120,000 NGVs on the road in the United States and more than 15.2 million worldwide.



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How does NGV performance compare to conventional fuel vehicles?
Horsepower, acceleration and cruise power are  the same. However, the typical range for an NGV running on CNG or LNG may be less than a conventionally fueled vehicle because of the lower energy content of natural gas.  Extra storage tanks can increase range.

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What are the benefits of natural gas as a transportation fuel and natural gas vehicles?
Economy and EnvironmentThere are many benefits, economic and social, to using natural gas vehicles. Here are just a few:

  • Natural gas is a domestic fuel, improving energy security and lessening the United States’ dependence on foreign oil.
  • Though the price of natural gas varies the same as gasoline and diesel, historically the cost of natural gas has been between $0.84 and $3.19 per equivalent gallon of gasoline. This makes natural gas as a transportation fuel very economic at the pump.
  • Exhaust emissions are generally much lower than gasoline-powered vehicles.

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What is the future of natural gas?
There has been much discussion recently about natural gas being the immediate solution for our nation’s oil dependence. It is produced domestically and an extensive distribution infrastructure already exists. It is also helping to pave the way for future technology development such as hydrogen fuel cells vehicles. Natural gas is a good feedstock for hydrogen that powers hydrogen fuel cell vehicles. Furthermore, as both hydrogen and natural gas are gaseous fuels, the lessons learned for developing natural gas technologies may pave the way for further hydrogen technology production.

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What incentives and laws are relative to natural gas as a transportation fuel, infrastructure and natural gas vehicles?
There are many federal and state laws and incentives related to natural gas as a transportation fuel, infrastructure and natural gas vehicles. For more information, visit the following websites:

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I’ve heard you can obtain home refueling for NGVs. How can I get it in my area?
Home refueling systems are also called Vehicle Refueling Appliances (VRA). There are a couple of products on the market for home refueling including the BRC FuelMaker’s Phill, distributed by IMPCO and NatGasCar’s Ecowise. A qualified dealer will be able to assess whether the VRA will meet your needs given your vehicle type, daily fuel needs, CNG tank size and pressure. Additionally, there must be natural gas service to your home.

Both VRAs should only be installed by trained and certified personnel. Check with your local utility company for more information.

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How do I become a Certified CNG Fuel System Installer?
The usual way to become "certified" to install a CNG fuel system is to be trained and "certified" by the company that manufactures the CNG conversion system such as IMPCO or Baytech Corporation, etc. In any event, the CNG fuel system MUST be installed in accordance with NFPA 52.

Two states (to date), Oklahoma and Texas, have their own certification requirements and exams.

  • Oklahoma’s Alternative Fuels Technician Examiners Program is through the Department of Central Services Home Page / Fleet Management / Alternative Fuels Program. Click here for more information.
  • Texas’ Authorized CNG/LNG Activities Licensing is managed through the Rail Road Commission of Texas. Click here for more information.

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How can I find a natural gas fueling station?
Find A Natural Gas Fueling StationThere are nearly 1,000 CNG stations in the United States, and new stations are coming online often. The AFDC has a fuel station locator with search options by fuel, state, and even routing capabilities:

There is also an application available for your smart phone:

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What are the prices of natural gas compared to conventional gasoline?
DOE’s EERE’s Clean Cities publishes a quarterly Alternative Fuel Price Report designed to compare alternative fuel prices in the US in relation to gasoline and diesel prices. The following chart shows the most recent data available for comparison. The report can be found here:


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Frequently Used Natural Gas & Vehicle Related Acronyms

AB 32

Legislation designed to reduce global warming impacts in California


Alternative Fuels and Advanced Vehicles Data Center


Alternative Fuel Vehicle


American Gas Association


American National Standards Institute


Air Quality Management District


American Society of Mechanical Engineers


American Society for Testing and Materials


British Thermal Unit




Clean Air Act Amendments of 1990


Corporate Average Fuel Economy


Clean Air Plan


California Air Resources Board




Congestion Mitigation and Air Quality Improvement Program


Compressed Natural Gas


Carbon Monoxide


Carbon Dioxide


U.S. Department of Energy


U.S. Department of Transportation


U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy


U.S. Environmental Protection Agency


Energy Policy Act of 1992 and/or 2005


Federal Highway Administration


Gasoline Gallon Equivalent


Gross Vehicle Weight Rating


Heavy-Duty Truck


Heavy-Duty Vehicle


High Occupancy Vehicle


Internal Combustion Engine


Inherently Low Emission Vehicle




Light-Duty Truck


Light -Duty Vehicle


Low Emission Vehicle


Local Distribution Company


Liquefied Natural Gas


liter per minute


Thousand Cubic Feet


Medium-Duty Truck


Medium-Duty Vehicle


Megapascal (35 MPa = 5000 psig = 350 bar)


Natural Gas Vehicle




National Highway Traffic Safety Administration


Normal Cubic Meters Per Hour


Nitrogen Oxide


National Renewable Energy Laboratory


Original equipment manufacturer




Particulate Matter


Particulate Matter Less Than 10 Microns in Diameter


Pounds Per Square Inch


Pounds Per Square Inch (Gauge Pressure)


Partial Zero-Emissions Vehicle


State Implementation Plan


Small Volume Manufacturer


Super Ultra-Low-Emission Vehicle


Ultra Low Emission Vehicle


Voluntary Airport Low Emission Program


Volatile Organic Compound


Vehicle Refueling Appliance


Zero Emission Vehicle

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Upcoming Training

Level 1: NGV Essentials
and Safety Practices

August 21, 2018
Atlanta, GA

Level 2: CNG Fuel System
Inspector Training

August 22-23, 2018
Atlanta, GA

Level 1: NGV Essentials
and Safety Practices

September 11, 2018
Boothwyn, PA

Level 2: CNG Fuel System
Inspector Training

September 12-13, 2018
Boothwyn, PA

Essentials of CNG Station Planning,
Design and Construction

September 24-25, 2018
Las Vegas, NV

Essentials of CNG Station
Operation and Maintenance

September 26-27, 2018
Las Vegas, NV

Level 1: NGV Essentials
and Safety Practices

October 2, 2018
Sacramento, CA

Level 2: CNG Fuel System
Inspector Training

October 3-4, 2018
Sacramento, CA


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About NGVi

Natural Gas Vehicle Institute is North America’s leading provider of training and consulting on natural gas as a transportation fuel.

Our services address the full range of natural gas vehicle and fueling issues, including:

Technical consulting services – Sizing and designing compressed natural gas fueling stations, vehicle assessments and technical assistance for fleets, CNG fueling station troubleshooting, natural gas vehicle maintenance facilities upgrades, liquefied natural gas fleet and fueling management.

Technical training – NGV Essentials and Safety Practices, CNG Fuel System Inspector Training, Heavy-Duty NGV Maintenance and Diagnostics Training, Light-Duty NGV Maintenance and Diagnostics Training, CNG Fuel System Design and Installation Training, Essentials of CNG Station Operation and Maintenance Training, Essentials of CNG Station Planning, Design and Construction Training and CNG/LNG Codes and Standards Training for Fire Marshals and Code Officials.


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