Natural gas fuels:

Natural gas as a transportation fuel

Turn the earth's great resource into your company's best resource with Agility Fuel Systems. Fuel represents as much as 25% of a typical fleet's operating costs; by fueling with natural gas, fleet owners can reducce fuel costs by more than 50%. Natural gas has been used in the transportation industry for over 15 years and has proven to be easy to use, safe and reliable.

There are two primary types of commonly avaialable natural gas fuel, compressed (CNG) and liquefied (LNG). Both are viable fuel sources for heavy duty vehicles. Depending on the end-users' requirements, either form may best-suited.

Agility Fuel Systems is the primary fuel system supplier to most of the leading domestic OEMs and natural gas fleets. We are experienced with both fuel systems, and provide a complete end-to-end product offering from the analysis and design phase through after-market service and warranty support for both fuel types.

Gas stored at high pressure at 3,600 psi Physical form Liquid produced cryogenically at -260F
4x Volume vs Diesel 2x
Lower cost to produce and store Cost Higher cost to process, liquefy and store
Easy Refueling Requires special handling equipment
60 - 4,500 psi System pressure 60 - 230 psi
Unlimited (no fuel loss) Hold time Limited (fuel will vent if not used)
Carbon fiber wrapped cylinders Storage Vacuum-insulated stainless steel tanks
New, lightweight large capacity CNG tanks enable long-haul trucking applications.   LNG's high energy density makes it relevant to trucking applications where space is at a premium.

Compressed Natural Gas (CNG)

Clean-burning natural gas has become the alternative fuel of choice for transit, refuse, and many other heavy-duty vehicles. High-strength and lightweight materials allow CNG pressures up to 3,600 PSIG, providing increased fuel storage capacities while keeping the total system weight low.

Agility's CNG fuel systems are designed to take advantage of all of the latest technological developments and pass the operating benefits through to the end user. Single fuel systems can hold up to five storage cylinders, while large bus systems can carry as many as twelve cylinders with a fuel capacity of over 27,000 SCF (194 diesel gallon equivalents).

Vehicles equipped with Agility's fuel systems comply with all Federal, state, and local regulations, and have an excellent track record for safety and reliability in the most demanding fleet applications.

In choosing CNG over LNG, a fleet operator should consider the relative advantages and disadvantages of CNG as a fuel.

Compressed Natural Gas

CNG Conversion Formulas

Pounds of CNG Fuel
Lbs. of CNG @ 3,600 PSI = Water Volume (cu. in.) multiplied by 0.0079
Lbs. of CNG @ 3,000 PSI = Water Volume (cu. in.) multiplied by 0.0069

Standard Cubic Feet (SCF)
SCF @ 70°F and 3,600 PSI = Water Volume (cu. in.) divided by 5.861
SCF @ 70°F and 3,000 PSI = Water Volume (cu. in.) divided by 6.657

Diesel/Gasoline Gallon Equivalents
Gasoline Gallon Equivalent (GGE) = SCF of Natural Gas divided by 123
Diesel Gallon Equivalent (DGE) = SCF of Natural Gas divided by 139

Liquefied Natural Gas (LNG)

Natural gas fuel for vehicles is also available in liquid form. For certain applications where weight and vehicle range are critical, LNG may be the perfect choice. LNG systems operate at low pressure and can store as much as 2.5 times the fuel in the same space as conventional CNG systems. LNG is transported and stored at extremely low temperatures and requires the use of vacuum-insulated storage tanks.

The Agility product development team has extensive experience working with cryogenic (-260°F) piping systems and has designed fuel systems holding as many as four storage tanks that mount on the roof or over the engine for transit applications. LNG fuel systems incorporate a proprietary Agility pressure control manifold, which reduces the number of system components and allows multiple storage tanks to operate as a single unit. All LNG systems include an integral containment pan designed to protect the passenger or engine compartment in the event of any fuel leakage.

The California Highway Patrol and the Texas Railroad Commission approve these systems.

In choosing LNG over CNG, a fleet operator should consider the relative advantages and disadvantages of LNG as a fuel.


LNG Pressure - Temperature - Density

Pressure (PSI) Temperature (°F) Density (Lbs/Gal.)
0 -259 3.54
50 -223 3.29
100 -200 3.11
150 -186 2.97
200 -175 2.85
250 -167 2.76
300 -158 2.68
350 -150 2.60