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Natural Gas Vehicles

How NGVs Work

Light-duty natural gas vehicles work much like gasoline-powered vehicles. In a CNG fuel system, high-pressure natural gas moves from the storage tank to the engine where its pressure is reduced to the engine’s required fuel injection system pressure. After the natural gas is injected into the engine, the fuel-air mixture is compressed and ignited by a spark plug. The expanding gases propel the vehicle.

Some heavy-duty vehicles use spark-ignited natural gas systems, but other systems exist as well. High-pressure direct injection engines burn natural gas in a compression-ignition (diesel) cycle. Also, diesel engines can often be converted to burn diesel and natural gas simultaneously in a dual-fuel system.

About Natural Gas Vehicles

Natural Gas Vehicles (NGVs) are powered by compressed natural gas (CNG) or liquefied natural gas (LNG). Both are cleaner, safer and less expensive than traditional fuels. New developments in engine and vehicle technology, more stringent air quality regulations, and government incentives make this choice increasingly attractive.

There are more than 15 million NGVs worldwide and 175,000 on U.S. roads. In the U.S., most NGVs produced directly at the factory by the vehicle manufacturer are buses, freight trucks, refuse trucks and other medium and heavy duty vehicles. However, there are also many models of gasoline-powered vehicles which can be converted to operate on CNG suitable for commercial fleet and consumer use.

Our nation has the most extensive natural gas distribution system of any country in the world, making it feasible to install CNG fueling equipment at existing gas stations and other locations supplied from existing natural gas lines. There are more than 1,700 public and private NGV fueling stations available now and the number is growing fast.

Are NGVs right for your business? Contact us for more information. Atlanta Gas Light can provide you with clean, affordable natural gas to fuel your vehicles and assist you with evaluating the vehicle and fueling options.

CNG + RNG = Lower Emissions

CNG vehicles reduce Greenhouse Gas (GHG) emissions by 15 – 21% on a well-to-wheels basis compared to conventional fuels, depending on the type of vehicle and operating duty cycles. When CNG vehicles are fueled with Renewable Natural Gas (RNG) from sources like landfills, wastewater treatment plants and biodigesters, they reduce GHG emissions by 70 – 90 %, or even carbon negative in the case of certain agricultural waste digesters. CNG vehicles are a proven technology that is commercially available today and can yield a positive ROI based on fuel cost savings alone. When combined with RNG, CNG vehicles are also the most cost-effective way to reduce GHG emissions and many fleets are incorporating them as a cornerstone of their sustainability strategy.

Benefits of Natural Gas Vehicles

Proven & Reliable

Nearly 15 million NGVs are in use worldwide, with more than 175,000 in the U.S.

Fuel Savings

The U.S. is the major producer of natural gas. This abundant domestic supply has driven down the price of natural gas, ensuring that the price will remain below that of gasoline and diesel. Compressed Natural Gas (CNG) currently saves up to 50% over conventional fuels, and CNG vehicles are available for all types of applications, including business fleets and vehicles for personal use.

Environmental Benefits

CNG vehicles produce up to 90% fewer emissions than gasoline or diesel and reduce greenhouse gases 15-20% over diesel and gasoline. If the CNG is sourced from Renewable Natural Gas (RNG) suppliers like landfills, water treatment plants, or agricultural waste digesters, the reduction in greenhouse gases is even more significant; in the 70-90% range or even carbon negative in some cases.

Reduced Maintenance Costs

Oil change intervals for NGVs may often be extended since natural gas burns cleaner than gasoline or diesel. Also, because natural gas engines have practically no carbon build-up, it is not uncommon for them to last longer than gasoline and diesel engines. Today's diesel vehicles require maintenance intensive exhaust treatment equipment such as Diesel Particulate Filters (DPF), Selective Catalytic Reduction (SCR), and Diesel Exhaust Fluid (DEF) to meet emission requirements. In contrast, heavy duty natural gas engines require only a maintenance-free exhaust catalytic converter so all that other expensive exhaust treatment equipment is eliminated.

Quieter

Heavy-duty NGVs have an 80-90% lower noise level than comparable diesel vehicles.

Incentives

Significant federal and/or state tax credits and other incentives are often available for converting to NGVs. For more information visit: www.afdc.energy.gov/laws

CNG Versus Traditional Fuels

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Business Fleets

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Natural Gas Vehicle Types

How NGV's Work

Light-duty natural gas vehicles work much like gasoline-powered vehicles. In a CNG fuel system, high-pressure natural gas moves from the storage tank to the engine where its pressure is reduced to the engine’s required fuel injection system pressure. After the natural gas is injected into the engine, the fuel-air mixture is compressed and ignited by a spark plug. The expanding gases propel the vehicle.

Some heavy-duty vehicles use spark-ignited natural gas systems, but other systems exist as well. High-pressure direct injection engines burn natural gas in a compression-ignition (diesel) cycle. Also, diesel engines can often be converted to burn diesel and natural gas simultaneously in a dual-fuel system.

Applications

Natural Gas Vehicles (NGVs) are developed based on the same internal combustion engines as gasoline and diesel vehicles and the performance is 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

Types of Fuel Storage

  • 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.

Available CNG Vehicles

In the light-duty category, there is a long list of late model vehicles for which there is an EPA approved after-market conversion system available. This includes many Ford vehicles available with the optional “gaseous engine prep package” (specially hardened engine components), making them eligible for conversion to CNG by Ford Qualified Vehicle Modifiers (QVMs). These vehicles can often be converted prior to delivery and purchased on a “ship-through“ basis from the dealer. To obtain information about after-market conversions and new or used vehicles that can be modified to operate on natural gas, visit NGV America.

In the medium- and heavy-duty categories, there are a number of dedicated and bi-fuel natural gas engines being manufactured today. For example, Cummins offers the B6.7N, L9N, and ISX12N, which are spark-ignited natural gas versions of the Cummins 6.7 liter, 8.9 liter and 11.9 liter diesel engines. These engines are certified to 0.02 grams of NOx per bHp-hr., which is 90% cleaner than the national standard of 0.2 g/bHp-hr. Beginning in model year 2024, Cummins also offers a 15 liter natural gas engine, the X15N, which is rated at 500 Hp and 1,850 ft-lbs. torque, large enough to handle even the toughest duty cycles such as long-haul interstate trucking. For more information visit Natural Gas Engines | Cummins Inc. These engines are available in all manner of heavy-duty vehicles; transit buses, refuse trucks, vocational trucks, delivery trucks, Class 8 tractor-trailers, etc. Just about every manufacturer of heavy-duty vehicles now offers CNG versions of their vehicles.

Safety

Natural gas in an inherently safe fuel and, unlike gasoline, it dissipates into the atmosphere in the event of an accidental release. The high ignition temperature and limited flammability range make accidental ignition or combustion of natural gas unlikely.

CNG vehicle storage cylinders and other fuel system components are manufactured to strict standards and installed in accordance with applicable codes.  The industry has an excellent safety record, especially when compared to other fuel types.

For more information on NGV safety, codes and standards applicable to NGVs and fueling equipment, and more, please visit NGVAmerica, which coordinates and implements a variety of public awareness, education, market research, codes and standards and technology programs for natural gas vehicles.