The Plain Truth About CNG Conversions in the United States

The Plain Truth About CNG Conversions in the United States

The CNG industry in the United States is unique, to say the least. Over the past 6 years, due to the high cost of gasoline and the low cost of CNG in some states, the US CNG industry has boomed.

This growth is a natural extension of low cost CNG being available and shops and individuals willing to do the conversions. These CNG pioneers had little help and much criticism but as they rolled out 1000’s of conversions consumers were able to cut their fuel budget with a renewable US-produced fuel.

In order to understand the CNG Conversion Industry in the United States let’s take a quick look at 3 things areas of the industry.

  1. CNG conversions and converters.
  2. CNG filling stations.
  3. Applicable CNG rules, regulations and certifications.

When we look at CNG conversions we need to understand:

  • CNG components (quality, supply and type)
  • CNG installers
  • The different types of CNG systems

CNG Components

All CNG components, no matter where they are produced, are subject to strict testing where worldwide ISO (International Organization for Standardization) standards are used. These are standards for high pressure pipes, valves, fittings and explain the regulations for mounting the pressurized components safely.

In the United States we use NFPA (National Fire Protection Association) standards and in particular NFPA 52 for high pressure tubing and tanks.

These standards are suggestions, in other words there is no agency that checks for compliance.

These standards are for “hard” parts only. They have nothing to do with system configuration, wiring, tuning or electrical.

CNG components are made worldwide. South America, Asia, Europe, Canada and the United States are the largest producers.

In the United States distribution and sales of CNG Components is very selective. The CNG system retailers are arbitrary as to who they sell to. It is a very complicated system.

EPA Certified Conversion Suppliers

There are CNG component producers that sell EPA Certified systems. These companies sell only to their converters (converters they have personally trained).

These EPA Certified converters are usually limited to installing EPA Certified conversions produced only by their component suppliers. They don’t “mix and match”.

Aftermarket Conversions

There are CNG component producers in the US that produce components for “Non-Certified” or “Aftermarket” systems.

Due to an unfound fear of the EPA these US suppliers usually won’t sell any of these systems or components inside the US.

All of the aftermarket converters in the United States must import their own components or buy their CNG Components from U.S suppliers that purchase from producers outside of the US.

This creates supply, warranty and tech support problems for aftermarket converters and suppliers.


Quick CNG Conversion Fact 

EPA Certified CNG systems are only available for new Chevy and Ford trucks and a few car models.

There are only a few OEM CNG Vehicles, a Honda Civic (CNG only or “dedicated”) a couple of GM Bi-fuel pickups and a Dodge pickup.

This means that 95% of all vehicles on te road have no “EPA Certified” systems available for them.


CNG Converters

I like to put CNG converters into 2 categories: “aftermarket” and “EPA Certified”.

Since the EPA Certified converters are limited to a small market they work mostly with fleets and small business owners. They only convert new or newer vehicles. Mostly trucks.

Their conversions are more expensive due to the testing that is required for certification. They are also limited to EPA Certified conversions only (as stated earlier) due to agreements they make with their EPA Certified kit suppliers.

The second group, aftermarket converters, can convert almost any vehicle. They come in a lot of different experience levels from relatively novice mechanics to ASE Master Techs with years of experience.

Types of CNG Systems

The first group (EPA Certified) mostly use sequential injection CNG systems made specifically for a particular car or truck. (Many older EPA Certified systems were aspirated.)

Aftermarket converters use aspirated as well as sequential CNG systems. These systems are universal and can be adapted and tuned to most vehicles. Worldwide, most CNG vehicles are aspirated.

Aftermarket conversions are thousands of dollars less and offer the “everyday driver” a chance to drive using CNG.

In most countries there is no “EPA Certified” vs “aftermarket” converters. There are just “converters”. Many countries have converted vehicles pass a simple one-time high pressure tank and fitting inspection to make sure the vehicle is safe.

CNG Filling Stations

In order for a vehicle to run on CNG you need a filling station. Most filling stations are commercial (anyone can use them) or private (for private company owned vehicles) only. There are also a few home fills but not many.

Over the past 40 years there have been many CNG stations built that are now shut down, in the late 90’s many stations nationwide were built using State and Federal money. Natural gas companies and private individuals put these stations in to service the CNG vehicles that were mandated as part of the CAA (Clean Air Act). Initially many of these stations were priced not much lower than gasoline since they had a captive customer base. As time went on and the State and Federal monies dried up, since the stations were not profitable by themselves most of them were closed.

Home Fills

Even though producing a home fill compressor is not “rocket science” no one has produced a low-priced, reliable home fill.

Even though many have tried to produce an economical home fill, as of now I know of no available units besides the Phill and the Fuelmaker (which are not reliable or economical).


In all of the countries that have been successful in converting their vehicles to natural gas the commercial filling stations are the standard.

Some countries have also used “mother and daughter” stations that used tank trailers to store CNG at the filling stations.



A Note On Quick CNG vs Gasoline

Have you ever wondered why the natural gas companies don’t promote natural gas vehicle conversions? Yes they may drive natural gas vehicles themselves but do little to help others to convert to CNG.

Some Natural Gas companies have installed CNG filling stations but most of those were paid for using federal or state grants or ratepayers money.

Where does most natural gas come from? There are natural gas wells and natural gas is also a byproduct of gasoline refining.

Natural gas companies buy much of their natural gas from the big oil companies. Big oil/gasoline companies don’t want competition for their gasoline cars. The market is fixed. It is profitable. They don’t want their transportation monopoly tampered with.

Could this symbiotic relationship be the cause of some people dragging their feet when it comes to promoting CNG conversions? Perhaps.


Applicable CNG Rules Regulations and Certifications

There are no national certifications for CNG converters. There is an ASE (Automotive Service Excellence) F1 certification that is for Alternative Fueled Vehicles. CSA (Canadian Standards Association) also has a CNG tank and high-pressure fitting inspection certification.

Some states (like Oklahoma and Texas) have an informational class they require if you have a CNG repair/conversion shop. Most states have no such requirements.

Some CNG system manufacturers have chosen to have their systems EPA Certified. This adds thousands of dollars in research and development.

Even though EPA Certification may make a system more dependable, all systems have problems.

EPA Certification only looks at what comes out the tailpipe. Most EPA Certified system up-fitters choose to incorporate NFPA 52 safety standards in their installs.

The downsides of EPA Certification are:

  • The Certification is only good for a few years (at most).
  • The system is not serviceable by anyone other than the manufacturer
  • They are only available to a small segment of the vehicles on the road.
  • EPA Certified vehicles are typically $10,000 to $20,000 more to convert.

The EPA does have other groups available besides “Certified”. There is also an “Intermediate” and “Outside Useful Life”.

These other groups let you send in test data along with technical descriptions of their systems and then you are listed as a EPA “Compliant” system on the EPA site.


As you can see the CNG industry in the United States can be quite confusing. There are many roadblocks and misconceptions.

The US CNG industry is tiny compared to other parts of the world. the US has only  200,000 natural gas vehicles out of over 250,000,000 vehicles on the road.

That’s 0.08%. One in every 1,250 vehicles.

We can do better than that. We will do better than that.

This entry was posted in Aftermarket converters, Automotive, CNG conversions, CNG kits, EPA, EPA Fanatics, EPA Hardliners, EPA regulations, Government, Green, mechanics, Regulation. Bookmark the permalink.

5 Responses to The Plain Truth About CNG Conversions in the United States

  1. cngvw says:

    Hello Thank you Jim.
    I do these kind of CNG conversions for many and Jim has been a great help.
    For my house hold we have 2 converted cars and a home build and tested home filling
    station. I have cut our gasoline cost by $300+ a month this way and I am glad we did.

    I really come down to do you wish to be tied to the uncontrolled raising gasoline pricing!!
    Bob Mann

  2. Pingback: Oldies but Goodies, CNG Articles from the past… |

  3. Lamp says:

    Current cost for a car conversion is much less than 10-20k, is it not?
    EPA Certification is necessary to drive the car on the road, is it not?
    Is it not also illegal to fit a working car with a CNG system and use it as a normal car–if the kit has not been EPA certified for your certain engine family?

    • Jim Younkin says:

      Most vehicles on the road have no EPA Certified kits for them. As long as the kit is installed safely the EPA is no problem

  4. ontarget28 says:

    The two issues I see necessary for me to commit are. The tank and home filling need to be affordable. The home filling system appears to be no more than a compressor and hose with the correct fitting. I would be interested to hear what cngvw used to create his system.

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