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Chemistry (including Biochemistry)/Liquefied petroleum gas (LPG) and Compressed natural gas (CNG).


Dear Dr Jeffery

LPG is used in domestic household for cooking purposes. They are available in the form of Pipeline and Gas Cylinders to consumers.

CNG is used as a fuel for driving Automobiles viz cars, buses, trucks etc. The CNG are available and filled by automobile drivers at Fuel filling stations viz Petrol, Diesel, Gas etc

I would like to know the following information from your end.

In case LPG is experimented to use as a fuel for automobiles
and CNG is experimented to use as a fuel for cooking purposes
what will be the effects ?.

In case LPG is experimented to use as a fuel for automobiles
then the automobile will not start because the engine expects CNG
or the automobile will start but it will not give the desired speed, mileage etc ?.

In case CNG is experimented to use as a fuel for cooking purposes
then the consumer will not be able to cook food, boiling water, milk etc ?.

What will be the effects if they are tried alternatively for different purposes ?.

Awaiting your reply,

Thanks & Regards,
Prashant S Akerkar

Hi Prashant:

Sorry for the delay.
A lot of this information is already on the internet, however you may not have the right search terms.

LPG in automobiles is already being used to limited effect(google Autogas).
CNG is also being used for cooking already (often used on boats).

In short LPG has about 1/3 less energy per L than regular gas and about 3 times more than per L of CNG.  LPG burns much cleaner than gasoline and slightly dirtier than CNG.
While CNG has a much lower energy density (joules/L) than LPG, it is safer in many ways (methane is lighter than air - this means that leaks will just rise into atmosphere).  Also CNG is basically a natural product, while LPG is manufactured.  This makes CNG a cleaner fuel IF it is manufactured nearby, but harder to transport in terms of total energy because it has less energy per liter.

You cannot put LPG as a substitute safely for CNG in automobiles designed for CNG and it should not be done.  Separate handling, injection and protection strategies MUST be taken.  Also, as combustion is based on the oxygen/fuel ratio, air intakes will be different.  In short, if you want to use LPG, you have to outfit the car to run on LPG.

No, CNG can be used to do all of those things, it just take a greater volume of it.

I hope this helps!  Take care.  

Chemistry (including Biochemistry)

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Dr. Jeffery Raymond


Materials chemistry. Materials science. Spectroscopy. Polymer science. Physical Chemistry. General Physics. Technical writing. General Applied Mathematics. Nanomaterials. Optoelectronic Behavior. Science Policy.


Teaching: General Inorganic Chemistry I & II, Organic Chemistry I & II, Physical Chemistry I, Polymeric Materials, General Physics I, Calculus I & II
My prior experience includes the United States Army and three years as a development chemist in industry. Currently I am the Assistant Director of the Laboratory for Synthetic Biological Interactions. All told, 13 years of experience in research, development and science education.

Texas A&M University, American Chemical Society, POLY-ACS, SPIE

Journal of the American Chemical Society, Nanoletters, Journal of Physical Chemistry C, Journal of Physical Chemistry Letters, Ultramicroscopy Proceedings of SPIE, Proceedings of MRS, Polymer News, Chemical and Engineering News, Nano Letters, Small,, Angewandte

PhD Macromolecular Science and Engineering (Photophysics/Nanomaterials Concentration), MS Materials Science, BS Chemistry and Physics, Graduate Certificate in Science Policy, AAS Chemical Technology, AAS Engineering Technology

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