Types of Natural Gas Sources

There are basically three sources of raw natural gas that are used for extracting the natural gas including petroleum crude oil wells, condensate wells and gas wells.

The raw natural gas that is extracted from petroleum crude oil wells the associated gas that exists separately from the crude oil in the underground formation, or dissolved in the crude oil.

The raw natural gas from gas wells and condensate wells do not have crude oil and is termed as non-associated gas. The gas wells produce raw natural gas while the condensate wells produce raw natural gas in addition to natural gas condensate.

The methane-rich gas occurs in the methane deposits in form of pores of coal seams and called as coal- bed gas. It is called as sweet gas as it is free of hydrogen sulphide. It primarily consists of methane with small quantities of nitrogen, ethane, and carbon dioxide. It does not contain butanes, pentanes, propane, or condensate.

Natural gas hydrate or methane hydrate is a solid structure that traps the methane within the crystal structure of ice. The significant deposits of methane clathrate are found under the sediments on the ocean floors and in the arctic regions. The amount of the worldwide methane reserves are not known significantly.

As per the recent estimates, the range of methane is from 1 to 5 × 1015 m3. It amounts to six to twenty nine times of the worldwide natural gas reserves that amounts to 175.4 × 1012 m3 from the conventional sources.  The technology for economically exploiting and extracting the methane from the hydrate reservoirs is not available.

Here m3 are defined at the conditions of temperature 0 °C and 1 atm (101.325 kPa) of absolute pressure.

Other types of gases such as landfill gas, town Gas, Biogas, and synthetic gas, are not natural gases as they are man-made fuels.

How to Compress Natural Gas

The compressed natural gas is basically a pressurized natural gas that is utilised for heating purposes. The natural gas is pumped to a gas fueling station in an uncompressed state and it is later compressed on site. It is done by using reciprocating compressor that uses positive displacement for reducing the volume of gas contained in a cylinder. Thus, it is possible to compress a natural gas for using it in specially designed vehicles and you only need to have Reciprocating compressor and

Reciprocating compressor lubricant as the required materials.

You should get a connection to a natural gas pipeline and for that you need to get in touch with the local natural gas company and government authorities. They will provide information on obtaining a connection from of natural gas from their pipelines. Once you have obtained the natural gas connection, you can get a reciprocating compressor that compresses natural gas from the pipeline into such a form that suits to be stored in a compressed natural gas cylinder. A reciprocating compressor can be used for safely compressing the natural gas up to pressures of around 3,600 pounds per square inch.


You should lubricate your compressor for optimal performance and you can use high-viscosity, non-detergent lubricant for that purpose as it is specifically designed for lubricating reciprocating compressors.  You are required to connect the reciprocating compressor to the natural gas pipeline. You should ensure that you have received authorization for using the natural gas from the pipelines.

You should also turn on your compressor as it will use a piston for compressing natural gas from the pipeline at low pressure into a highly pressurized form. This highly pressurised form is suited for vehicular use.


The CNG kit comprises of the following components as mentioned below.

(1) The Cylinder – The cylinder is used for storing the CNG at a work pressure of 200 Bar. It comes with a shut-off valve and a safety burst disc. The cylinders are usually approved by the Chief Controller of Explosives of the Indian Government.

(2) The Vapour Bag – It comes fitted onto the cylinder and used for enclosing the cylinder valve and the pipes that are connected to it and vented out of the car

(3) The High Pressure Pipe – This High Pressure Pipe is used for connecting the refuelling valve to the CNG Cylinder as well as the Pressure Regulator.

(4) The Refuelling Valve – The Refuelling Valve is applied for refuelling the CNG cylinder.

(5)The Pressure Regulator – The Pressure Regulator comes with a Solenoid Valve for shutting off gas supply to the engine. The CNG which is stored at a high pressure gets reduced to below atmospheric pressure in the cylinder by this unit. This negative pressure is basically a safety feature that does not allow gas to pass in case the engine is not functioning.

(6) The Gas-Air Mixer – It is a unique component that is designed specially to suit the every engine model. It also measures the gas fed into the engine precisely.

(7) The Petrol-Solenoid Valve – It is used to removing the petrol supply to the engine when the engine is run on CNG.

(8)The Selector Switch – The Selector Switch allows the driver to select either the CNG mode or the petrol mode for running the vehicle. This unit comprises of electronics that ensures safety by switching off the gas solenoid in case the engine is switched off. It also acts as a fuel indicator for the amount of CNG present in the cylinder.

Drawbacks of using CNG

Natural Gas is considered to be more expensive for storage and transport as compared to liquid fuels or coal. The natural gas produces the same smog wastes and green house gases as was observed in other fossil fuels although in lesser quantities. Moreover, the natural gas is not so energy dense as liquid oil and therefore you are required to use more of it to get the same amount of power out of it.

A gas consumes more space as compared to the liquid material.  For storing the natural gas, you are required to freeze it and that procedure is costly.  On freezing it, it becomes liquid that can be pumped around. Another alternative is to use the high pressure that needs special pumps and air tight system.  Thus, it takes more energy to move the material and for this reason, most of the oil wells burn off the additional natural gas as waste rather than refining or using it.


It is possible to refine the Natural gas from oil that is found in oil wells. It can also be produced organically by refining methane from trash heaps and landfills that are subjected to decomposition. The presence of natural gas in the coal mines makes it one of the explosive risks of mining. As it can be produced from decomposition of wastes, natural gas is regarded as the superior fuel for replacing oil but it is less dense and difficult to store and transport than oil.


The common uses of natural gas includes the production of electricity, and to be used as a cooking gas as Liquidized Petroleum Gas. This LPG is liquid natural gas and is extremely useful in heating and stoves. It is adapted to be used in airplanes and automobiles. One of the major difficulties in the usage of natural gas is its storage and transportation because of its low density.

Creation and Composition of Natural Gas

Creation of natural gas – The occurrence of the Natural gas in the earth takes place in the form of natural gas deposits.  The distribution of the natural gas is scattered and cannot be predicted with certainty. The various reservoirs of the natural gas vary a lot in their geologic history. The creation of natural gas took place from the organic matter over millions of years. The organic matter used in the process belonged to marine or coastal ecosystems. The decomposed organic matter from dead plants and animals got covered in layers of sediments and mud gradually. The continued deposition of the decomposed organic matter in the layers piled on top of previous layers led to the increase in pressure and temperature. This increased pressure and temperature transformed the organic matter gradually into methane-rich gas and oil. This natural gas rise towards to earth’s surface after its formation through pores and fissures till the time they got trapped between the less permeable rock layers and created reservoirs of natural gas.

Composition of raw natural gas – The natural gas in its natural form consists of following ingredients.

(1) The natural gas consists chiefly of methane (CH4) that is regarded as the shortest as well as lightest hydrocarbon molecule.

(2) Apart from methane, natural gas also consists of different amounts of higher molecular weight gaseous hydrocarbons.  The raw natural gas comprises of 20 % volume of ethane, normal butane, isobutene, pentanes and higher molecular weight hydrocarbons. They are collectively called as a NGL (Natural Gas Liquids), when they are processed and purified into finished by-products.

(3)Mercaptans such as methanethiol (CH3SH) and ethanethiol (C2H5SH)

(4) Acid gases like carbon dioxide (CO2) and hydrogen sulphide (H2S)

(5) Gases like Nitrogen (N2) and Helium (He).

(6) Water in form of water vapour and liquid water.

(7)Liquid hydrocarbons

(8)Mercury in elemental form and in form of compounds.

Advantages of Compressed Natural Gas

One of the biggest advantages of CNG is that it is environmentally clean gas that is cleanest burning fuel used in operations today. It implies less vehicle maintenance and extended engine life.

The emissions of the CNG vehicles are least among any motor fuel. In fact, the Dedicated Natural Gas Vehicles (NGV) does not have any emissions during fuelling. The fuelling emissions account for at least 50% of total hydrocarbon emissions of vehicle.


CNG produce considerable less pollutant as compared to gasoline. The emissions released by gasoline operated vehicles are not environment friendly as they release pollutants like carbon dioxide that leads to global warming. This phenomenon is reduced with natural gas. It also contributes to the reduction of maintenance costs by as much as 40% on conversion of vehicle from gasoline to CNG. The intervals required for maintenance and tuning of vehicles are extended from 30,000 to 50,000 miles. Also, the intervals between oil changes are dramatically extended anywhere from 10,000 to 25,000 additional miles on the basis of how a particular vehicle is used.


Natural gas do not react to metals like the gasoline, therefore the pipes and mufflers get extended life. The performance of Natural gas is similar as compared to gasoline in a converted vehicle. The dedicated CNG engines are better in performance than gasoline engines. The octane rating of CNG is 130 and scores above gasoline slightly in efficiency. As CNG is already in a gaseous state, the vehicles operated on CNG have excellent starting and driveability irrespective of severe hot and cold weather conditions. There is very less chance of vapour locking and it experiences less knocking.


The CNG is also cheaper per equivalent gallon as compared to other fuels like gasoline. On an average it is 15% to 50% less cheap than gasoline. There are only few minor modifications required for converting a gasoline-powered car to CNG.  The results from the Safety Advantage Surveys indicate that CNG operated vehicles are safer than those powered with other fuels.


Tips for CNG Users

If you are using a CNG operated vehicle then you can follow the below mentioned tips for better car mileage and proper care.

(1)  Ensure to tighten the gas lead – CNG tends to evaporate from the gas tank in case it has a small opening, therefore you need to ensure that the lid is closely tightened. In fact, the missing or damaged gas caps led to the evaporation of millions of gallons of gas every year in India. Therefore you need to tighten up the gas cap every time you fuel up your car.

(2) Keep your tyres inflated – You can make big improvement on car’s gas mileage up to 15 percent. You should not drive on under-inflated tires as they will lower down mileage and wears down easily.

(3) Ensure proper filling of CNG gas – You should try to prevent over-inflation of gas in the fuel tank. As soon as you get the signal that your tank is completed, stop pumping the fuel.

(4) Do parking if your vehicles in shade –  you should try to park of your car in the shade as it will help in preventing a greater amount of evaporative emissions in the presence of direct sunlight.

(5) Check your tire pressure – You should purchase a digital gauge and compare the pressure in your tires with the recommended pressure as mentioned in your manual. If you feel that pressure is less, you can inflate the tires as required.

(6) Use a garage – You should use a garage for proper parking as it helps the car stay warm in winter and cool in summer.

(7) Replace air filters – You should regularly replace the clogged air filter as it could improve the gas mileage by 10 percent and makes savings up to15 cents per gallon.


Natural Gas proves to be an ideal fuel source for numerous reasons including safety. It is lighter than air and it will rise and quickly dissipates in the atmosphere. Both CNG and LPG are natural gas; however they differ from each other in their properties.

The comparison between the CNG and LPG can be done as follows:

(1)    CNG is compressed Natural Gas that is economical, clean burning, domestically available alternative fuel source for vehicles. While liquefied petroleum gas is a hydrocarbon fuel that is lighter than petroleum and can also be used as an automotive fuel.

(2)    CNG will require higher initial investment while the LPG needed lower initial investment.

(3)    CNG comes with lower running costs while LPG needs higher running costs.

(4)    CNG offers lesser power delivery in comparison to increased power delivery in case of LPG

(5)    With CNG, there are fewer requirements of tune ups, while in case of LPG more refined tune ups are required.

(6)    CNG is stored in the bulkier and heavier storage tanks while LPG is stored in a smaller and tighter storage tanks.

(7)    CNG is available at only limited outlets while LPG is available at most of the places

(8)    CNG is a clean fuel with no carbon deposits while LPG is also delivering cleaner emissions.

(9)    CNG is very safe fuel that is lighter and possesses higher ignition camp while LPG is heavier with lower ignition temperature.

(10) CNG is widely popular with commercial vehicles, taxis and autorickshaws while LPG is famous among private vehicles like cars.

Examples of Cars with CNG options are Chevrolet Optra, the Mitsubishi Lancer, Tata Indica and Indigo, Marina, Ford India and others.

Examples of Cars with LPG options include Suzuki Wagon R Duo and Omni, Tata hatchback and estate and others.

Clean Alternative for Gasoline

The emission of the greenhouse gases is one of the disadvantages of standard gasoline and other types of fossil fuels. These gases affect our climate and acts as a major source of air pollution. The continued use of fossil fuels for powering of internal combustion engine is being debated. The compressed natural gas proves to be effective and clean alternative to gasoline. This fuel is created by compression of traditional natural gas and its storage in the canisters. It can be used in many ways including the clean fuel for internal combustion engine operating in numerous motor cars. It is also becoming famous in Europe and South America due to continuing rise in gasoline prices.

South America has the largest market share of global Natural Gas Vehicle with 48% of the total NGV. The CNG cars have proven to be major alternative to gasoline-driven models. It is done by retrofitting gasoline models with the CNG Kit needed for operating the vehicle on CNG rather than gasoline. The usage of CNG is practised a lot in Brazil and Argentina that run approx 3 million of the world’s fleet out of 7 million NGVs. In fact, most of the taxi cabs in these two countries are CNG based and takes the benefit of government initiative for making the conversion to CNG cheaper and easier. As South America has the largest reserve of natural gas, most of the countries are increasingly using the CNG.

There has been continuous rise in CNG in the developed countries of the world.  One of the major factors that attract the persons to use CNG is that it is cheaper alternative and those who run it would pay up to 60% less as compared to gasoline. It is environmentally friendly gas that is answer to our needs of clean fuel in today world that is threatened by the global warming.

Do’s and Don’ts of CNG

DO’s while using CNG

(1) The vehicles operating on CNG must comply with the required conditions as contained in the central motor vehicles rules.

(2) Before installing the CNG kit, it is required to ensure that the workshop is authorized. You should check the safety standards and code of practices observed by workshop in kit installation and commissioning.

(3) You should have the approved Kit and cylinder that goes well with the make of vehicle.

(4) You should ensure that the vehicle should undergo the needed pre-conversion checks completely

(5)You should have thorough leak test of the gas system.

(6) You should collect the installer certificate from the workshop

(7) You should ensure to endorse the CNG or bi-fuel mode in Registration Certificate issued by RTO

(8) You should do an annual check of the CNG kit and keep the associated certificates.

(9) You need to ensure that the CNG Cylinder follow the Gas cylinder rules. You also need to ensure that it is hydro tested once in five years

(10) As a driver, you should always have the Certificate of CNG kit, Fitness and hydro test.

(11) You should acquaint yourself with the CNG mechanism by taking essential precautions for driving a CNG vehicle
 Don’ts while using CNG

(1) You should not purchase components from various sources and do not install the kit yourself

(2) You should not modify or improvise the kit at unauthorized workshops

(3) You should not install an LPG, Propane in place of CNG cylinder

(4) You should not do filling of LPG, Propane or other fuel in a CNG cylinder

(5) You should ensure that there are no passengers on board at a time of filling of CNG

(6) You should not ignore any signs of gas leakage if observed by you.