Talk:Compressed natural gas

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Efficiency compared to MCFC and electric mobility[edit]

An ICE has a low efficiency in a car. Since compressed natural gas cars have only a short range, they are mostly used in city traffic, where the ICE has an even worse efficiency.

When the gas is instead used in a Molten-carbonate fuel cell with Steam turbine behind to produce electricity with 64% efficiency, a Plug-in hybrid or Battery electric vehicle could drive 4 times more km with the same gas than an ICE car. --Pege.founder 06:34, 2 August 2006 (UTC)

SuperGirl uses CNG as a weapon?[edit]


The female of the alien Unity was killed when Supergirl threw a can of compressed flammable gas, possibly Compressed_natural_gas, at it, which embedded into the creature, she then ignited the gas canister with her heat vision, which exploded in a giant fireball, blasting the creature apart.

I think you should discuss this “super girl” subject elsewhere. This is not appropriate to this article.Ragingmaster 17:20, 18 October 2007 (UTC)

CNG has less energy than gasoline?[edit]

Is it true that CNG is weaker than gasoline. It's quite a common rumor; I'm not sure if it's true. By weaker I mean: slower acceleration, less towing power, etc. If this is true, why is CNG used in transit? —Preceding unsigned comment added by Zybez (talkcontribs) 02:16, August 29, 2007 (UTC)

It is much cheaper then all other kinds of common fuel, and it is environmentally superior, emitting considerably less pollution to the atmosphere. And yes, it really is “weaker” then other kinds of fuel (5% less power to de vehicle), but this is more a matter of technology than of the fuel itself. I believe that, with time, the engines will adapt better to this kind of energy. Ragingmaster 17:02, 18 October 2007 (UTC)
In the same engine, CNG will indeed produce less power in a gasoline designed engine that has not taken advantage of the higher octane rating of CNG (130+). This is due to the fact that an internal combustion engine's power is determined, in a large part, by compression ratio which the most significant factor is limited by octane rating. Natural Gas requires more oxygen per unit energy produced than gasoline, therefore, in the exact same engine, it would produce less power running CNG. However, in an engine designed for CNG, this can be made up for with more aggresive timing and higher compression, due to the high octane rating of CNG. CraziFuzzy (talk) 09:19, 7 June 2008 (UTC)

Natural gas automobile[edit]

I have read the articles on previous pages, however what I want to know is: I have a LPG converted panelvan, can I use the same set-up with CNG eg gas tank and carburator/injecters and refuel from my house mains gas supply with an appropriate compressor? —Preceding unsigned comment added by (talk) 11:37, 4 May 2008 (UTC)

The short answer is no. Your LPG storage tank could not be used to hold CNG, as it is nowhere near rated for the high pressures CNG requires. CNG Cylinders are the most expensive part of a CNG conversion, as they are rated for storage of 3600#. Also, much of the regulation components would need to be replaced, as they are designed for dealing with the liquid stored LPG. CraziFuzzy (talk) 09:22, 7 June 2008 (UTC)

Anybody got a handle on cost of converting an older vehicle -say a late 90's minivan or a 5 year old Buick? What about cost of a home filling center like the "PHILL" How about the cost of geting gas installed from a gas line across the street? - I know thats going to vary by the utility, but a ballpark figure or a sampling of what it cost others would help. -Unsigned. —Preceding unsigned comment added by (talk) 04:03, 8 October 2008 (UTC)

As of April 2009, FuelMaker of Toronto, Canada, the original maker of Phill is dead. The assets of FuelMaker were purchased by Fuel Systems Solutions] of Santa Ana, California, which subsequently moved its headquarters to New York City. The Phill units are still being made in Cherasco, Italy by their BRC FuelMaker subsidiary, but you can't buy one in the U.S., as far as I know; they're only available on lease for about US$50 per month, making them uneconomical for low-use motorists. I've seen numbers in the vicinity of $5,000 to get a home CNG refueling station set up, when you figure in the cost of special electrical wiring and gas plumbing. In California and other places where they use "baseline usage" billing for electricity and natural gas it's a particular concern, because the additional gas and electric usage for refueling a car would consistently put the utility customer into the second or third rate tier, making it prohibitively expensive to light and heat one's house. One way to avoid that is to have secondary gas and electric meters installed just for the refueling station, which entails paying for permits and professional installation services. — QuicksilverT @ 21:02, 31 October 2012 (UTC)


This article covers Canada, Europe, South America, and Asia, but not the United States. I am not knowledgable about this topic, but perhaps someone who is could add such a section. —Preceding unsigned comment added by (talk) 08:01, 6 June 2008 (UTC)

  • Started United States section. Feel free to elaborate, as I just started with a summary of current situation. CraziFuzzy (talk) 08:34, 8 June 2008 (UTC)

P.c. McKenzie Company is the world wide distributor of Ingersoll Rand's complete line of natural gas compressors for NGV refueling. They are located in Pittsburgh, PA. link title

Not sure who wrote the last line about certifying conversion systems, but it is vague and not worded very precisely. I suspect the "$50,000" is the cost to a certified outfitter, rather than to a car owner, but I don't know and it leaves no link to verify. — Preceding unsigned comment added by Thegeniusboy05 (talkcontribs) 05:42, 2 March 2011 (UTC)

The cost to convert a passenger car to CNG is more on the order of US$2,000, according to some numbers I've stumble upon on the 'net. — QuicksilverT @ 21:02, 31 October 2012 (UTC)
  • As of March 2015, the entire United States section of the article seems dated.

I started to update it, but my first set of edits got reverted.

The cites included a government alternate energy website and the Texas Railroad Commissioner (who collects taxes for CNG fuels sales).

I disagree with the reversion, but I will leave it to others to re-perform the edits. Gregfreemyer (talk) 14:38, 30 March 2015 (UTC)


Like the above "America?" section. Japan is the biggest producer of CNG vehicles. Why isn't even the word "Japan" on article at all? Maybe there is some one with knowledge of the subject for Japan that can write some information...? I heard there was a CNG Pirus in Japan but don't know if it is true? —Preceding unsigned comment added by (talk) 10:25, 11 June 2008 (UTC)

Don't know where you get the information that Japan is the biggest producer of CNG vehicles. Most CNG vehicles come from Europe (Volvo, Opel, VW, FIAT, Merc-Benz). Some manufacturers liek VW also supply CNG models in Brasil and Argentina for the latin-american market. —Preceding unsigned comment added by (talk) 05:13, 12 March 2009 (UTC)

Global warming potential[edit]

The article mentions the interest from environmental grounds of CNG, but does not talk about the Global warming potential of it relative to refined extracted petroleum. This article from claims that CNG has higher GWP, due to the normally incomplete combustion of methane in CNG engines. I haven't found exact figures comparing GWP; still it seems that this topic needs a mention in the article. --- Charles Stewart(talk) 18:51, 28 August 2008 (UTC)

The chemistry of combustion, whether burning gasoline or natural gas, entails the conversion of carbon compounds into carbon dioxide. The energy density of natural gas, 53.6 MJ/kg (Mega Joules per Kilogram) is quite a bit higher than that of gasoline, at 46.4 MJ/kg. Also, some of the energy obtained from burning gasoline goes toward breaking down the larger molecules. In addition sometimes the conbustion process is incomplete, resulting in unburned hydrocarbons, and carbon monoxide. Therefore burning natural gas is indeed more efficient than burning gasoline.

However the point being that burning natural gas DOES still contribute to global warming potential (if you believe in that sort of semi-science). If you are serious about converting to a CLEAN fuel you'll go with Hydrogen. The only byproduct of combustion of Hydrogen is water vapor... OH WAIT! Water vapor is a WORSE "greenhouse gas" than Carbon Dioxide.
- David B. - Fuel Science Chemist and part time global warming detractor

And hydrogen isn't a fuel, it's an Energy carrier not a Primary energy source like methane. "Greenhouse" gases are emitted during the production of hydrogen. There's no free lunch here. Santamoly (talk) 16:22, 20 October 2011 (UTC)
Global warming potential is irrelevant. The carbon cycle is a closed cycle. Whatever energy comes out of burning hydrocarbons is eventually recaptured in the formation of new hydrocarbon compounds. Instead of talking about global warming potential, we should be considering the profit-making potential of people who push such alarmist rubbish on society. — QuicksilverT @ 21:02, 31 October 2012 (UTC)
The key word is "eventually". There is a time delay before any recapture, which allows greenhouse gases to accumulate. The result depends on the rates of various processes. The recapture rate won't automatically increase with increasing CO2 emissions, but rather with increasing levels. Thus, increased emission of CO2 raises its equilibrium level in the atmosphere, which then raises its actual level and its ability to trap infrared radiation. (talk) 03:48, 1 September 2013 (UTC)

"Octane" rating is important[edit]

Propane has an equivalent octane rating of around 100 which allows the use of engines designed to use a 12:1 compression ratio. This yields much more power than a gasoline engine (8 to 10 : 1 compression). Merely converting the fuel used in a gasoline engine to natural gas or propane will NOT be an optimal conversion unless there are substantial modifications such domed pistons or smaller cylinder head combustion chambers which either or in combination would increase the compression ratio. The question is: does compressed nat gas have the very high octane rating that propane has? Homebuilding (talk) 22:37, 8 March 2009 (UTC)

CNG has HALF the BTUs of propane[edit]

In the ready to burn state, CNG has HALF the BTUs of propane. This accounts for the more sophisticated tanks and higher pressures.Homebuilding (talk) 22:37, 8 March 2009 (UTC)

Energy density[edit]

What is the energy density of CNG in MJ/kg ? -- (talk) 00:35, 8 October 2008 (UTC)

  • That depends on the source of the natural gas you use to make it. It's somewhere between 36 and 50 MJ/kg, depending on the source of the gas.Gerben1974 (talk) 06:24, 11 November 2008 (UTC)

Comparisons with LPG, LNG, etc[edit]

I get confused between all the different "Gas" alternatives. Is there an article that gives an overview and comparison of these related fuels? Thanks. Stepho-wrs (talk) 03:09, 31 October 2008 (UTC)

  • The first reference link of this website has an overview. In short: LNG is natural gas (NG), but liquefied (L) by cooling it to extremely low temperatures, LPG is a different gas (propane+butane), which can be liquefied by compressing it. CNG is gaseous. NG can only be made liquid by deep cooling, so if that is too expensive, you compress it, to reduce the volume. Gerben1974 (talk) 06:31, 11 November 2008 (UTC)

CNG direct injection[edit]

if cng is directly injected in to the combustion chamberof conventional cng engine , is it nessesary to change exhaust manifold —Preceding unsigned comment added by (talk) 08:53, 29 January 2009 (UTC)

Managing exhaust gases after combustion has always been far less critical than the intake side which involves mixing air and (various) fuel(s) in appropriate proportions, sometimes involving turbocharging or supercharging. No matter the fuel, the rotary engine (Mazda and others) presents the greatest challenges pertaining to exhaust heat and degradation of castings or tubing, as there is far less "cooling" time between exhaust pulses, compared to an otto-cycle engine where exhaust heat is introduced only about 1/4 of the time. Of course, the introduction of oxidizers in the fuel (nitrous oxide) and oxygenated fuels (methanol or ethanol) could be expected to degrade exhaust castings/tubing faster than a gasoline engine using ambient air. Homebuilding (talk) 05:14, 5 February 2010 (UTC)

India (rupee price)[edit]

The rupee price needs to be dates since obviously it is subject to change. Such as "On 1 January 2009, the price in India was"... SimonTrew (talk) 08:02, 22 March 2009 (UTC)

Compressed natural gas in Brazil[edit]

About compressed natural gas in Brazil, I must write that compressed natural gas has being used in Brazil, in commercial basis, since 1991.Agre22 (talk) 16:19, 27 October 2009 (UTC)agre22

Energy recovery[edit]

Is it possible to add a section energy recovery ? About generator loaded expanders and compressor loaded expanders ? Thanks Mion (talk) 11:15, 4 November 2009 (UTC)

Gas quality specifications[edit]

Seems to me a section ought to be added to at least generically cover the topic of gas quality specifications regarding CNG. For example, California has CARB standards (13 CCR §2292.5) and NFPA 52 has standards (originally?) based on SAE J1616. Obviously other standards would apply in other countries as well. At a minimum, components and contaminants covered by such specifications could be bullet-listed. At the other extreme (of detail), a table could be added comparing standards from various locations. Sound reasonable or should this be a separate topic? CheMechanical (talk) 00:01, 19 May 2010 (UTC)

When is it not worth buying CNG[edit]

As Petrol and Diesel give more mileage per litre at which price difference ratio between the fuels would it be uneconomical to fill up with CNG? Would anybody know the answer to this. Maybe this could be interwoven into the article. Many thanks —Preceding unsigned comment added by (talk) 19:27, 14 September 2010 (UTC)

New Zealand experience with alternative automotive fuels[edit]

It is true that at its peak 10% of road vehicles in New Zealand had dual fuel conversions; this figure includes both the LPG/petrol and CNG/petrol conversions then available.

A government subsidy was available in the form of an interest free loan covering the cost of these conversions.

In practice it was discovered the CNG conversion option had many tuning problems, which when added to the limited range of CNG vehicles, made these conversions less practical than equivalent LPG conversions.

Consequently all CNG filling stations eventually were closed, the equipment sold overseas. New Zealand now has only one CNG filling station, close to a drag strip.

Government subsidies eventually were dropped. Without the government subsidies automotive gas conversions became impractical. The price of LPG rose. Distributors offer a discount to bulk users of LPG; consequently LPG became uneconomic as an automotive fuel unless used in a high mileage vehicle. It is now used as a fuel in the taxi industry, but rarely otherwise.

Manufacturers now offer factory built LPG dedicated vehicles, which solve the tuning problems inherent in aftermarket fuel conversions. These vehicles are only offered for sale to taxi operators. (talk) 20:40, 19 December 2010 (UTC)


I removed the following statement from the "Drawbacks" section:

Engine life also will get reduced by 30% or more due to failure of proper lubrication and less efficiency.

It was added by User: (contribs) and looks illegitimate. I could find nothing corroborating that. If anyone wants to put it back, then find a citation. Otherwise, I think it's just "original research". Scott Dial (talk) 23:26, 28 January 2011 (UTC)

Actually, just the converse is true: with diesel or gasoline/petrol as fuel, piston-ring blowby causes dilution of crankcase lubrication, reducing lubricity/protection, increasing wear, with a cumulative effect of poorer efficiency and increased damage over time. With NG, propane, helium, or any "true" gas, there is still blowby, but no noticeable dilution of lubricants, ergo no cumulative wear/damage. Can't source, but I'll look into it.
Ragityman19:31, 4 February 2012 (UTC) — Preceding unsigned comment added by (talk)

Diesel to CNG[edit]

does it is possibel to convert a diesel enigen to cng — Preceding unsigned comment added by Ksy.ysk (talkcontribs) 07:19, 4 July 2011 (UTC)

Yes, but to pass new emissions tests, more modifications such as EGR are needed. Westport Innovations is one such developer. Santamoly (talk) 16:31, 20 October 2011 (UTC)
There are buses and trucks with Diesel engines running with compressed natural gas (CNG) and liquefied natural gas (LNG). It is not only possible to convert a Diesel engine to CNG, it is being done commercially. — QuicksilverT @ 20:23, 31 October 2012 (UTC)


What's the meaning of "In lion CNG equipped vehicles on the road" (Worldwide; Africa and Middle East)? I need it for a translation in Italian (Gas naturale compresso). Is Lion a Africa or Middle East's state? Please answer me.

P.S. My english is correct?

--Moro, il veneto (talk) 14:55, 9 July 2011 (UTC)

That phrase doesn't appear in the article Santamoly (talk) 07:31, 14 November 2011 (UTC)
Santamoly didn't answer your other question: your English IS correct, and a lot better than my Italian. (or his, probably) The English in the phrase you were asking about was not so good, though, and I guess someone else agreed, 'cause they deleted it!
Ragityman69.171.178.83 (talk) 20:02, 4 February 2012 (UTC)

Dead link[edit]

Please, someone, fix the dead link. I tried it, and you have to click on another link, and then another, to get to: <>, which is where the last of the tech info is, but you have to look for those links, and I'm sure that's what confused the bot. Sorry, footnote number 6 (or 5?) I'm not able to make the correction. (Handheld, and the browser's not cooperating.) Thanks! Ragityman — Preceding unsigned comment added by (talk) 20:34, 4 February 2012 (UTC)

Carbon neutral?[edit]

"CNG may also be mixed with biogas (produced from landfills or wastewater), resulting in a fuel that does not increase the concentration of carbon in the atmosphere." Mixed or produced from? If mixed then it will still increase CO2 concentration, just at a reduced rate.

"It is stored and distributed in hard containers at a pressure of 200–248 bar (2,900–3,600 psi), usually in cylindrical or spherical shapes". I am interested to know what storage methods are not steel, or not cylinders or spheres? If it's a small niche application then I think being more specific is more helpful... 'it is almost always stored in steel gas cylinders or spheres'

Mike163 (talk) 00:20, 19 May 2013 (UTC)


The last section has very little detail, and following the cited link the article is no longer hosted. The link does give the name of a company, however a search of that company doesn't reveal anything relating to diesel natural gas. — Preceding unsigned comment added by (talk) 04:07, 4 April 2014 (UTC)

Thermal efficiency[edit]

I think the overall thermal efficiency of a CNG system must be very low because a lot of energy will be wasted as heat during compression and this energy will not be recovered when the gas is burned. I suspect that CNG is only cost-effective because of the tax advantages. Could we please have some information on overall thermal efficiency in the article? Biscuittin (talk) 14:14, 9 August 2014 (UTC)

I can't find anything about this on the internet. The energy (presumably electrical energy) used to compress the gas just seems to be ignored. Biscuittin (talk) 14:39, 9 August 2014 (UTC)