NGVConnection Newsletter - August 2011
Natural Gas Fueling Infrastructure:  Strategies Bring Outcomes
By Annalloyd Thomason, Vice President/General Manager, NGVi

This is the second in a series of articles on the state of the NGV industry, where we’ve come from, what we’ve learned and where we need to go to move natural gas significantly ahead in the transportation fuels mix.


In 1996, the NGV industry introduced the “National NGV Industry Strategy.”  It was the laborious result of eighteen months of research, interviews, analysis, economic modeling and consensus building.  NGVi was one of three consulting firms hired by the Gas Research Institute (now Gas Technology Institute), American Gas Association and the Natural Gas Vehicle Coalition (now NGVAmerica) to bring forth a plan that would help the industry successfully penetrate the market for natural gas vehicles and fueling.

One of the most significant hurdles identified during the development of the strategy was the enormous cost of building fueling infrastructure and identifying where the funding could/would come from.  Carl Moyer, our now deceased and greatly missed colleague from Acurex Environmental (now TIAX LLC), coined the phrase “mystery investor” during the project, because after identifying all the “regular” funding sources like government incentives and traditional investors, there was still a significant gap between the amount of money needed and the amount of money available.

One of the strategies to help overcome this infrastructure funding gap was to point the NGV industry towards a focus on high fuel use fleets such as transit agencies, refuse trucks and delivery fleets.  Indeed, this focus helped increase demand for natural gas for transportation threefold between 1997 and 2009 to over 26 million gasoline gallon equivalents (GGE.)  Looking back, this strategy can be declared a success in terms of helping build demand for natural gas quickly. 

One example of this quick growth is the transit market.  In 1995, natural gas buses accounted for only 2% of 11.7 million gallons of the total fuel used by transit buses.  Over the next 13 years, diesel consumption in transit buses decreased by 15%.  The published figures for 2008 show natural gas transit buses using 153.4 million diesel gallon equivalents and accounting for 22% of the total fuel used by these vehicles.

Another outcome occurred, however, which also can be attributed at least in part to the focus on high fuel use fleets—a significant decline in the number of CNG stations.    In 1997, the United States achieved its maximum number of CNG fueling stations to date of just over 1,400.  There had been over 1,000 stations brought online in the five years since 1992 when the Energy Policy Act was passed that required federal, state government and utility company fleets to begin purchasing significant quantities of light-duty alternative fuel vehicles, including natural gas. 

A large percentage of the high fuel use fleets called out in the National NGV Industry Strategy required fueling infrastructure sized and designed specifically to dispense larger quantities of fuel and/or required or preferred onsite fueling, and had little or no potential to fuel at the typical CNG stations that had been constructed to date.  As a result, there began an upswing in the quantity of natural gas for transportation sold each year, but a corresponding decline in the number of CNG stations operating in the U.S.

The decline in the number of CNG stations in the U.S. began in 1997, but held relatively steady until 2001 when the total number was approximately 1,200.  By 2004, the number of CNG stations had dropped below 1,000 for the first time in just over a decade.  The number of stations began to level off in 2006, and modest growth is seen beginning in 2008.

The chart below demonstrates the correlation between the U.S. CNG station counts between 1997 and 2009 and the total natural gas consumption for transportation during that same time period.  This is perhaps the most revealing illustration of the sharp increase in CNG sales during a period when the number of stations was actually declining. 

Source: The U.S. Energy Information Administration (EIA)

So what do we learn here from the past?  There are at least two obvious conclusions.

First, jump-starting market demand with high fuel use vehicles was indeed successful.  Tripling the quantity of natural gas sold as a transportation fuel in less than a decade was a significant achievement and has given the NGV industry great impetus for the development of medium and heavy-duty natural gas engines that power a variety of vehicles in the market today.

Secondly, however, if our industry is ever to significantly penetrate the light-duty fleet and consumer markets, these customers must have ready access to convenient fueling infrastructure.  There are currently 159,000 retail outlets for gasoline in the U.S., and an additional 5,000 truck stops.  It has been said that when the diesel industry decided to expand the market for its fuel beyond heavy-duty trucks and began developing public infrastructure, a target of 10% of the number of gasoline stations was established to create a network convenient enough to encourage and facilitate the transition to diesel fuel. 

If that same target is applied to CNG, it means building a minimum of 16,000 CNG stations in the U.S. located at traditional retail gasoline/diesel outlets where customers are accustomed to obtaining fuel.  The good news is that recent CNG corridor and fueling project announcements are aligned with this principle, and the industry as a whole seems headed in that direction.  The predictable outcome for this new strategy will be increased branding and awareness for CNG, which when paired with competitive pricing and convenient access, will increase demand for both vehicles and fueling.  That is an outcome which provides a win for both purchasers and sellers of natural gas as a transportation fuel.

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Bid Specifications for Natural Gas Vehicles
By Leo Thomason, Executive Director, NGVi

Fleet managers and their staff are experts at writing vehicle specifications for gasoline and diesel vehicles.  Natural gas vehicles (NGVs), on the other hand, are not exactly like their gasoline and diesel counterparts.  NGVs have unique characteristics that fleet managers should be aware of that will help ensure successful incorporation of NGVs into the fleet.  

High-Pressure Fuel Storage System

For NGVs fueled with CNG, natural gas is highly compressed and stored onboard vehicles in high-pressure storage containers called CNG fuel storage cylinders or simply CNG cylinders. All CNG-powered vehicles have a high-pressure fuel system onboard the vehicles that enable them to use CNG.  These high-pressure systems are safe and are designed and regulated in accordance with National Fire Protection Association (NFPA) Code 52 for Vehicular Gaseous Fuel Systems. However, unlike gasoline and diesel fuel systems, CNG fuel systems currently do not come with a standard way to bleed down the high-pressure CNG fuel system should a component in that portion of the fuel system require maintenance. This could pose a potentially dangerous situation for the maintenance team.


Bid Specification Recommendation: To ensure the safety of the fleet maintenance team, the installation of a bleed valve in the high-pressure fuel line is recommended to provide an easy and safe way to reduce pressure prior to loosening and disconnecting a fitting to remove and replace a component. This bleed valve requirement must be specifically stated in your bid.


CNG Cylinder Useful Life

CNG fuel storage cylinders have a 10, 15, 20 or 25 year useful life from the date of manufacture and there is no way to extend life of the cylinder past the expiration date.  The cylinder’s expiration countdown begins from the date it was manufactured and NOT the date it was installed on the vehicle.  After the expiration date, cylinders must be properly disposed of and new cylinders purchased and installed to keep the vehicle in service.

Although cylinder life cannot be extended beyond the expiration date, the desired cylinder life can be specified in the bid specification.  Most fleet managers are unaware of this. 


Bid Specification Recommendations:

Cylinders should be specified to be no more than six months from the date of manufacture at the time of vehicle installation.  This will allow for maximum cylinder useful life in fleet service.

When specifying the cylinder’s useful life (10, 15, 20, or 25 years), it is recommended that a useful life of the cylinder specified for the vehicle be at least equal the expected useful life of the vehicle in fleet service.  However, it may benefit you to purchase a cylinder with a useful life beyond the vehicle’s life in fleet service in order to maximize the value of the vehicle subsequently sold at auction. 

CNG Cylinder Weight

CNG fuel storage cylinders are available in four different Types:

  • Type 1 are typically lowest in cost per unit of storage volume, but are the heaviest per unit of storage volume. 
  • Type 2 and 3 cylinders are more expensive per unit of storage volume compared to Type 1, and are lighter weight per unit of storage volume than Type 1. 
  • Type 4 can be more expensive per unit of storage volume than type 2 or 3, and can be lighter in weight per unit of storage volume than type 2 and 3. 
    • It is important to note that there are Type 3 cylinders available that are equal in weight per unit of storage volume as well as price per unit of storage volume to comparable Type 4 cylinders. 

Because of the added weight of cylinders, the Type and number of cylinders specified will affect the Gross Vehicle Weight Rating (GVWR) of the natural gas vehicle.  It is also important to note that CNG fuel storage cylinders weigh more when full of CNG than when they are empty.  This will affect vehicle suspension and brake life, thus impacting the maintenance of the vehicle. 

Bid Specification Recommendation: When considering the Type and number of cylinders, consider specifying cylinders that are as light in weight as financially feasible to lessen the impact on vehicle suspension and brake life. In addition, the GVW of the vehicle with the specified cylinders full of CNG with the total cargo weight needs to be considered when specifying CNG fuel storage cylinders types and quantities.


Vehicle Range

Because the body design of virtually all NGVs currently available in the United States are adapted from gasoline or diesel vehicles, they were not designed to utilize cylindrical fuel storage tanks or vessels that are required to contain the high-pressure CNG. Current vehicle manufacturers or fuel system integrators must find sufficient space on these vehicles to install enough high-pressure CNG storage cylinders to allow the vehicles to travel an acceptable range. In many cases the resulting range of the vehicle powered by CNG can be less than the same vehicle powered by gasoline or diesel. 

Bid Specification Recommendation: When considering the number of cylinders, the vehicle specification should clearly indicate the miles that the vehicle is expected to travel before needing to be refueled with CNG, keeping in mind that extra cylinders means extra weight that can displace payload capacity as mentioned in #3.


NGVi Options

If you need help developing bid specifications for NGVs for your fleet, NGVi can help. We offer a wide variety of fleet consulting services and trainig programs to assist exprienced NGV fleet managers and those new to NGVs.

For more informatio contact Lawrence McBride at 702-254-4180 or via email at

Minimizing Risk for Natural Gas Powered Transit Operations
By Annalloyd Thomason, Vice President/General Manager, NGVi

Increasingly, transit operators are adding natural gas powered buses and other vehicles to their fleets.  A variety of reasons affect these decisions, including economics and environmental concerns.  Natural gas powered fleets can achieve very favorable economics due to the operating characteristics of the vehicles and the competitive cost of fuel.  In addition, there are a wide variety of buses and other vehicles to choose from today that meet transit operators’ needs.  And natural gas powered buses can provide unparalleled environmental benefits.

Because of the very nature of their business, transit providers are focused on safety and are experienced at minimizing risk for their diesel powered fleets.  While the focus on safety for natural gas powered fleets should be equal in effort, the strategies for minimizing risk in these fleets differ radically because the fuel itself is different.  Here are five risk management “musts” for any transit provider that operates natural gas powered buses or other vehicles in their fleet.

Properly Designed and Constructed Fueling Stations

Most transit providers utilize onsite fueling sized and designed for their operation.  Because compressed natural gas (CNG) fueling stations deal with high pressure gas, it is imperative that these stations be designed by an experienced company and according to the prevailing codes, standards and industry best practices that help ensure safety.  It is also crucial that stations be constructed to these same standards—and that the proper installation of each piece of equipment is verified.  Fueling equipment that is not installed properly can be a significant source of risk.

Standardized Fueling Station Maintenance Plan

The CNG fueling industry is decades old, and has developed best practices for proactive, scheduled and emergency maintenance for fueling stations.  The goals of the maintenance plan include managing maintenance activities, monitoring system operation, providing emergency fueling support, enhancing equipment reliability, and delivering clean fuel to vehicles.  By implementing an appropriate  maintenance plan, potential problems can be foreseen and safely resolved  that could otherwise result in a serious outcome. 

Properly Constructed/Modified Vehicle Maintenance Facilities

Existing vehicle maintenance facilities are constructed to ensure safety when dealing with liquid fuels, which, when leaked, pool on the ground.  Natural gas, on the other hand, rises in the event of a leak because it is lighter than air.  This primary difference is the principal behind the requirements for vehicle maintenance facility modifications necessary to facilitate maintenance of natural gas powered vehicles.  Regardless of whether an existing facility is being modified for NGV maintenance, or a new facility is being constructed, there are three primary considerations:  ventilation, heating systems and potential ignition sources.  Transit maintenance facilities must be evaluated to ensure that they are safe for NGV maintenance.

Expert Training for Mechanics and Other Technicians

Because natural gas is very different than liquid fuels, mechanics and other technicians must be trained by industry experts on the safe maintenance practices for these vehicles.  They must be familiarized with the high-pressure fuel system and its components and how to safely de-fuel vehicles before certain vehicle repair procedures are implemented.  This training is critical to ensuring the safe maintenance and operation of the transit fleet.


Expert Training for Drivers and Fuel Handlers

Safety is the most critical training need for NGV drivers and/or fuel handlers because of their daily contact with the fuel delivery system, storage and fueling equipment.  Drivers and fuel handlers must be trained on the safety systems located at the fueling station and on natural gas powered buses and other vehicles, as well as safe operation of natural gas dispensing equipment.  This training will not only instill confidence in drivers and fuel handlers but will dramatically reduce risk by properly educating these employees.

Transit providers who successfully implement these five risk management strategies will seriously reduce the likelihood of a preventable incident related to natural gas powered vehicles and fueling.  If you would like additional information about how to develop or implement these strategies for transit providers, contact NGVi at 800-510-6484 or

Number of CNG Conversion Companies Grows
By Kasia McBride, NGVi Staff

Fleet operators have long been interested in the possibility of converting their vehicles to a cleaner more economical alternative fuel.  They have faced challenges—not the least of which has been the lack of a wide variety of conversion systems.  In recent years, there has been a significant increase in the number of conversion systems available, allowing converted vehicles to become an increasingly popular solution for fleets wanting to add natural gas vehicles to their mix.

A converted natural gas vehicle is an original equipment manufacturer (OEM) vehicle with an engine designed to run on conventional gasoline or diesel that has been altered aftermarket to operate on natural gas. There are two types of converted natural gas vehicles:

  • Dedicated vehicles operate only on natural gas, and there is no gasoline fuel system present
  • Bi-fuel vehicles operate on either natural gas or gasoline. Bi-fuel vehicles typically retain their original gasoline fuel tank, but are retrofitted with additional CNG tank(s).  

Regardless of whether the converted vehicle is bi-fuel or dedicated, all natural gas conversions must comply with United States Environmental Protection Agency (EPA) emissions standards. Additionally, converted vehicles operating within California or within states that have adopted California Low Emission Vehicle Standards must also meet California Air Resource Board (CARB) emissions requirements. To obtain EPA and CARB certification, conversion  system manufacturers must submit a converted vehicle to CARB and EPA for rigorous testing. One or both of these agencies may issue a certificate of conformity for the vehicle tested. This certification is not for the specific vehicle, but rather the vehicle’s engine family or engine test group.

At present, there are nearly a dozen manufacturers offering EPA certified systems, and this number is growing. This increase is due to increased vehicle demand, which is influenced by several factors, including:

  • An extended period of very high gasoline and diesel prices
  • Increasingly stringent federal and state laws which mandate improvements for gasoline and diesel fuel efficiency, as well as required reductions in green-house gas emissions
  • Growing awareness of the benefits of natural gas, demonstrated in various success stories reported in the media
  • Increased available funding for natural gas vehicle programs due to the American Recovery and Reinvestment Act (ARRA)

Another important factor is that as of March 2011, the EPA adopted a new and much simpler approach that streamlines the process by which manufacturers of natural gas conversion systems may demonstrate compliance with vehicle and engine emissions requirements. Not only is the process simpler, but EPA expects the improved approach will also result in a cost savings for many conversion companies.

Previous EPA regulations required vehicle and engine conversion systems to be covered by a certificate of conformity to gain a regulatory exemption from potential tampering charges. The new compliance program enables conversion manufacturers to qualify for an exemption from tampering by demonstrating that the converted vehicle or engine satisfies EPA emissions requirements.

These revised procedures are based on the age of the vehicle or engine being converted. EPA has found that the procedures for older vehicles and engines can be streamlined, while still adhering to environmental safeguards.

Overview of Program Elements

Vehicle/Engine Age

Conversion Manufacturer Requirement

Certificate Issued?



Example for 2011





MY >= current calendar year – 1

MY 2010, 2011, 2012 and < useful life mileage

Exhaust, Evap, and OBD testing

Certification application


Intermediate age

MY <= current calendar year - 2 and < useful life

MY 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009  and < useful life mileage

Exhaust and Evap testing + OBD scan tool test and attestation

Compliance submission


Outside useful life

Exceeds useful life

MY2001 and older or > full useful life in mileage

Technical justification and OBD scan tool test and attestation

Compliance submission


Source: EPA

The demonstration and notification requirements for vehicles and engines that are two model years old or newer still involve a certification process, similar to the previous procedure. But, once certified, an annual recertification will no longer be required to maintain the tampering exemption. The notification and demonstration requirements for intermediate age vehicles and engines will include testing and submission of data to show that the converted vehicle or engine continues to meet the applicable standards. The notification and demonstration process for vehicles and engines outside their normal useful life cycle involves submission of a description of the conversion system that provides sufficient technical detail to determine that the conversion will not increase the vehicle’s emissions. All vehicles that are two model years or older will no longer be required to obtain a certificate of conformity for such systems, and they will no longer have to pay certification fees.

For years, industry observers have expressed a mixture of both enthusiasm and frustration at the potential for vehicle conversion systems to change the availability of natural gas powered vehicles for fleets.  Now that the frustrations have been eased by the new EPA rules, we see more conversion systems coming to market every week.  This benefits fleet managers, the environment and the natural gas vehicle industry as a whole.

CNG Fuel Price Report
From Clean Cities Alternative Fuel Price Report published by Argonne National Laboratory for DOE's Clean Cities Program

Overall Average Fuel Prices (as of July 2011)


Nationwide Average Price for Fuel This Report

Nationwide Average Price for Fuel Last Report

Change in Price This Report vs. Last Report

Units of Measurement

Gasoline (Regular)




per gallon





per gallon





per GGE

NGVs & CNG in the News
NGVi Sponsors

Daily News 08/31/11

More Oil & Gas discovered in Texas, NJ puts 1-year moratorium on fracking, New conversions now available from BAF, Chicago launches CNG fast lane

Daily News 08/30/11

Clean Energy secures more investment, Natural Gas Loop UT-CA-NV, Sacramento OKs 53 NGV Refuse Trucks, Clean Cities Fleet Analysis Model

Daily News 08/29/11

Largest CNG Project in US just got bigger, PA DEP issued clean grants, AT&T reaches 3000th CNG milestone, New CNG Station in Santa Ana

To read more, click here.


Question of the Month Upcoming Training from NGVi

Q: Can the life of my CNG cylinder be extended?

A: There is a perception among some CNG powered NGV owners that the fuel storage containers on their vehicle can have the stated useful life extended by having them inspected and possibly hydrostatically tested.  This perception is totally false.  This perception started and has been reinforced by uninformed and/or untrained individuals.

CNG vehicle fuel storage containers are designed, manufactured, tested, and qualified according to the requirements of the U.S. Department of Transportation (U.S.DOT) National Highway Traffic Safety Administration (NHTSA) Federal Motor Vehicle Safety Standard (FMVSS) 304, Compressed Natural Gas Fuel Container Integrity. These vehicle fuel storage containers may also meet the requirements of ANSI/NGV 2 (2007), Basic Requirements for Compressed Natural Gas Vehicle (NGV) Fuel Containers.

ANSI/NGV2 establishes the requirements that vehicle fuel storage container manufacturers must design, manufacture, test and certify their containers for sale in the United States.  According to ANSI/NGV2 vehicle fuel storage containers may have a useful life of 10, 15, 20, or 25 years from the date of manufacture.  All vehicle fuel storage containers manufactured to the ANSI/NGV2 Standard must have a label indicating among other things the expiration date of the container.  U.S.DOT NHTSA FMVSS 304 states that when the vehicle fuel storage container life as indicated on the manufacturers label has been reached the container must be removed from service.  Additionally, the 2010 version of National Fire Protection Association (NFPA) 52, Vehicular Gaseous Fuel Systems Code, Chapter 6, Paragraph states that “Fuel containers whose service life has expired shall be removed from service”.

CNG Cylinder Sticker with Expiration Date

There are no inspections, tests or other techniques that can be used to extend the manufacturers marked useful life of any CNG fuel storage container installed on an NGV in the United States.

Please contact NGVi for more information.

CNG Fuel System Inspector Training
September 13-14, 2011, Dallas, TX

CNG Fueling Station Design Certification Course

September 15-16, 2011, Dallas, TX

Click here to Register

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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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