CNG – Useful Facts

(1) LPG was previously used as a fuel in the automobiles, however nowadays it is CNG that is widely used. Methane is the chief component of CNG while LPG consists of propane, butane and other chemicals.

(2) An LPG-fuelled vehicle did not run on CNG as both fuels are different from each other as they have different calcrific values. They also need different air-fuel ratios for combustion.

(3) You can retain the petrol carburettor during the conversion of your vehicle to CNG.  It is done so that your car still runs on petrol once you run out of CNG. The dashboard contains a switch that allows you to shift from CNG mode to petrol mode and vice versa.

(3) The savings on fuel cost by using CNG depends on various factors such as size, fuel consumption characteristics and mileage of the vehicle.

(4) You can occasionally use petrol as it serves to lubricate the carburettor in addition to improve the performance of the engine.

(5) CNG is a safer fuel than petrol, diesel or LPG as its specific gravity is lighter than air and that allows it to rises up and dissipates in the air. The ignition temperature of CNG is 700 degree Centigrade as compared to 455 degree Centigrade for petrol. Also, the storage of CNG is much safe than petrol, as the designing and construction of CNG cylinders are done from special materials and with high safety specifications.

(6) CNG is filled with a maximum pressure of 3000psi/g in a cylinder.

(7) The CNG kit is durable to boot and is easy to service. It is recommended to have optimum efficiency regular checks after every 10,000 km.

(8) In addition to petrol engines, the diesel vehicles can also be converted to CNG. In fact, majority of the public transport in metros are converted from diesel to CNG.

Uses of Natural Gas

Fertilizer – The natural gas is also used in the production of ammonia that is used for the fertilizer production.

Hydrogen – Another major use of the Natural gas is in the production of hydrogen by using the steam-methane reforming (SMR) process. The hydrogen obtained by this process can be used in wide range of industrial applications such as chemical industry, fuel source in hydrogen vehicles and a hydrogenating agent.

Aviation – The application of the natural gas in the aviation sector is also explored upon by the Russian aircraft manufacturer Tupolev that seeks to develop LNG and hydrogen variants of the Tu-204, Tu-334 passenger aircraft, and Tu-330 cargo aircraft. By using the liquid methane as a jet engine fuel, one can get more specific energy as compared to the standard kerosene mixes.  Moreover, it can also be used for lowering the temperature of the exhaust.

Petrochemicals – The various constituent of the natural gas can be used for the production of petrochemicals.

Clean fuel – Natural gas is widely preferred as it is a clean fuel and addresses the concerns of global warming caused by the gasoline products. The usage of natural gas as combustion fuel causes far less emissions of air pollutants like sulphur dioxide and nitrogen oxides as compared to the combustion of fuel oils. While using the natural gas as a combustion fuel, some amount of it gets leak into the atmosphere. As the leakage is very small, it is not of big concern.

Feedstock for various chemical products – the natural gas extracted from raw natural gas reservoir can be used for the production of petrochemicals, ammonia, hydrogen, and fertilizers.

Natural gas heating systems are widely used where it is used for heating the water and also for drying the clothes.

CNG in South Asia

The usage of CNG in South Asia is increasing gradually with Pakistan has emerged as a dominant player with highest number of CNG operated vehicles not only in Asia but the world over. Pakistan is followed by Argentina, Brazil and Iran. In addition to this, Pakistan boasts of the highest number of CNG stations across the world with over 2600 stations. This conversion of gasoline based vehicles to CNG is driven by the cheaper price of CNG as compared to petrol. The official vehicles and luxury vehicles only run on petrol in Pakistan. In Karachi, the new CNG Buses had been recently introduced by CDGK.  Except Honda, the majority of the car manufacturers in Pakistan are producing company fitted CNG kit versions. However, the hikes in CNG prices have resulted in the failing to initiate the big projects of the stakeholders in this sector. As the competition among the manufacturers will rise, the price of the CNG and Kits will eventually reduced.

CNG has emerged as a clean alternative fuel sources not only in Pakistan, but also in India and Bangladesh. The usage of CNG is required for the public transport system as per the law in Indian cities of New Delhi and Ahmadabad. The Delhi Transport Corporation (DTC) is currently operating the largest fleet of CNG buses of the world. In fact, there are many rickshaws and personal vehicles that are being converted to CNG powered technology in India and Bangladesh. The cost of the conversion is in the range of $800–$1000. There is not even a single auto rickshaw without CNG in Dhaka since 2003. The cost of CNG in India is in the range of Rs 31.47 per kg as compared with Rs. 55.00 per litre of petrol. The major benefits of CNG include immense cost savings, reduced emissions and environmentally friendly cars.

Uses of Natural Gas

There are many useful application of the natural gas across the various sectors of the industries such as power generation, Transportation fuel, Fertilizer, Aviation, Domestic use, Fertilizer and many others.

Some of the common uses of the natural gas are as follows:

Power generation – The chief application of the natural gas is in the generation of the electricity via using of gas turbines and steam turbines. There are many grid peaking power plants and off-grid engine-generators that use natural gas. The gas turbine is combined with the steam turbine for achieving the high efficiencies in combined cycle mode.

The usage of Natural gas in power generation is preferred as it is clean fuel as compared to other fossil fuels like oil and coal. It leads to the production of less carbon dioxide every unit of energy released. It can be widely used in areas where the gas can be made available at reasonable costs.  The usage of Fuel cell technology may also offer cleaner options for the conversion of natural gas into electricity as it is not so price-competitive.

Domestic use – The usage of natural gas in homes is intended for variety of applications such as cooking in natural gas-powered ovens, centralised heating, heating, and cooling or clothes dryers. The natural gas induced heating may be used for heating purposes in furnaces, boilers, and water heaters. Compressed natural gas (CNG) is usually supplied to the homes via the pipelines. In those areas, where there are no connections of piped-in public utility services, CNG is used with portable pipe grills. As CNG being less economical than LPG, the dominant source of rural gas is LPG.

Transportation fuel – CNG is a cleaner option to other automobile fuels like gasoline (petrol) and diesel fuel. Some of the countries that have highest number of CNG vehicles include Pakistan, Brazil, Argentina, Iran and India. The energy efficiency of CNG is equivalent to gasoline engines. Those gasoline/petrol vehicles that are converted to run on natural gas deliver less power because of low compression ratio of their engines. CNG-specific engines make use of higher compression ratio.



CNG Safety

The processed natural gas is very inflammable; however it is odourless and essentially colourless. Therefore to detect the presence of natural gas for leakage is required for preventing a fire or explosion. To do that, small amounts of a mercaptan( t-butyl mercaptan) that has strong unpleasant smell is added as an odorant to the natural gas. These odorants are considered to be non-toxic in the very low concentrations. The odorizing of natural gas started in the US after 1937 New London School explosion had killed over 300 students and faculties.  The presence of natural gas in the coal mines is detected by using the methane sensors as any coal-bed methane does not have any odour.  The mining equipment is also specifically developed for avoiding the ignition sources.

Every year, there are few incidents of explosions caused by natural gas leaks. The affected structure includes small businesses, individual homes, boats and others. It happens when an internal leak accumulates the gas inside the structure. The blast is enough to cause significant damage to the building. These cases of explosion may lead to minor to moderate injuries to the people. In very rare occasions, the natural gas gets build up in high enough quantities for resulting in a deadly explosion. This large scale explosion may leads to disintegration of few buildings in the process. The gas is lighter and tends to dissipates readily in the outdoor surroundings. However, it may get accumulated in dangerous quantities if suitable weather conditions prevail.

There are tens of millions of structures around the world that uses fuel and that makes the individual risk of using natural gas significantly less. The natural gas heating systems are basically a minor source of carbon monoxide deaths in the US.  In fact, the improvements in natural gas furnace designs led to reduction of CO poisoning accidents. The presence of advanced detectors warn of unsafe levels of explosive gases.

Steps for Fuelling Vehicle with CNG

You can take the following steps for fuelling the vehicle with CNG

(1) You can replace the fuel storage tank of your vehicle with bottles that have the ability of handling high-pressure gas. The natural gas is stored at 3,000-3,600 pounds per square inch in the vehicle. The storage containers can also withstand pressure and comes with special vents for releasing the pressure in times of emergency fire.  You can attach the special tube-shaped containers at the rear end or top end of the vehicle body. It should be of considerable structure for carrying the increased weight.

(2) You can install a regulator close to the engine for reducing the gas pressure at a time of its release from the tank. By using a regulator, the pressure of the CNG decreases before it enters the engine and gets converted into useable form.

(3) You can use the special engine parts for retrofitting the car to use CNG. You can also install a gaseous fuel injection system for replacing the gasoline fuel injection system. The different system is required for utilizing a gaseous fuel and feeding it into the cylinders that turn the pistons.

(4)  You can install the specialized sensors for monitoring and adjusting the fuel-to-air-flow mixture. It is required for the efficient burning of the fuel when the spark plug ignites the gas.

(5) You can use natural gas fuelling nozzles for fuelling the car. CNG needs a closed system as it is highly flammable. In fact, any air-to-natural-gas mixture in the range of 5 percent and 15 percent is flammable. These natural gas nozzles lock and seal the place for preventing gas from escaping at a time of fuelling.

(6) You can install natural gas refuelling station at home for pumping your own gas. It needs a dedicated circuit along with a 15-amp breaker and is tied into the natural gas line. It requires 48,00 BTU input.

Natural Gas Conversion

The recent hike in petrol price has forced many car drivers to switch their gasoline based combustion engine to CNG based combustion engine. One can easily save money and fuel at the same time by opting for CNG vehicles. There are basically 9 CNG vehicle models that are available for the general public from the car manufacturers like ford, Honda and GM. One of the best ways of combating global crisis is to run the car by using compressed natural gas. It does not require you to buy a new CNG vehicle and majority of the vehicles that runs on gasoline are readily converted to bi-fuel vehicle. The process usually needs expensive natural gas conversion kits that cost from $8,000 to $16,000.

This process of conversion of the gasoline based engines to the gas based engine is an extensive process that requires you to do test series to be conducted by the Environmental Protection Agency for ensuring that the system does not violate the rule. The major concern includes the test to ensure that the exhaust internal sensor system is not increased. This process needs a good amount of initial investment.

If you can make the initial investment, then you can save money and fuel in the long term. By using the CNG as the fuel for the vehicle, you can make savings in the long term. The increase in fuel price will inspire the car drivers to opt for the natural gas conversion process. There are many car manufacturers that are offering both the gasoline mode and CNG mode of operating the car engine. Prior to going for the conversion, you should check if your vehicle has approved conversion. Some of the cars that come with approved conversion are Ford Grand Marcus, Ford Crown Victoria, GCM Sierra and Lincoln Town Car.


The Fuelling Process and Bi-fuel Possibility

There are basically three types of CNG refuelling stations including fast fuelling stations, slow fuelling stations and combined fuelling stations.

Fast fuelling station – They are fast in fuelling process and takes only five to ten minutes for refuelling. These are ideal for retail roadside pumps.

Slow fuelling stations – They are slow in the fuelling process and may take five to eight hours for refuelling. It is ideal in cases of fuelling the fleet of vehicles that have long idle time.

Combined Fast and Slow fuelling stations – These fuelling stations have the facility of both fast and slow fuelling stations and they cater to both the above categories.

CNG is a compressed natural gas that is stored at compression stations that are connected with the gas pipeline directly. In this case, the gas is compressed at a required pressure that aids in fuelling. It is also possible to transport CNG to other retail outlets by using the cylinder trucks. These trucks carry lots of cylinders that provide CNG to fuel stations that are not connected by pipelines. These fuelling stations are usually placed alongside petrol and diesel pumps.

Bi-fuel Possibility

It is possible to operate the vehicles in the dual mode such as Petrol-CNG and Diesel-CNG. Thus, vehicles can be run on either petrol or on CNG.  There are many companies that have used this dual mode experiments successfully such as Kirloskar Cummins Ltd, Ashok Leyland, IBP, Delhi Transport Corporation, TELCO, OIL, and Gujarat Road Transport Corporation.

The Gas Authority of India Limited (GAIL) has proposed the use of CNG for vehicle manufacturers to undertake conversions on their vehicles. The actual performance of the vehicles can be monitored by Indian Institute for Petroleum. There are large reserves of natural gas in many countries around the world. It is likely that CNG would soon replace the petroleum products as dominant fuel.

Exploration and Extraction of Natural Gas

Exploration – The exploration of the Natural gas involves the searching for its occurrence under the ground or under the sea. The natural gas reserves are usually found in those places where there are impermeable rocks known as cap rocks that restrict the upward movement of gas via underground soil and rocks. The seismology is a technique employed by the geologists and geophysicists for searching areas that have the suitable conditions for a gas or oil deposit. In addition to that, there are high-speed computers that develop the three-dimensional underground maps.  The satellite image technology is also used widely for searching the natural gas reservoirs.

Those areas that have large reservoirs of natural gas are called as gas fields. Some of the famous gas fields of the world include North Field in Qatar.  Those gas fields that occur in underwater gas reservoirs are called as offshore fields such as North Sea, the Persian Gulf and the Gulf of Mexico.

Extraction – Once the gas field is explored, the next step is extraction of the gas from the field. The extraction of the gas from the field involves the drilling of the production wells for confirming the existence of a reservoir, its size and subsequent extraction of the gas. Once a gas well is found and it is drilled to the required depth, the gas rises automatically to the surface due to its own pressure . The gas flow rate decreases over time and it is maintained by drilling the reinjection wells and using the gas compressors for re injecting the compressed gas in downward direction into the reservoir.

With the continuous extraction of the gas from the field, there is subsequent decline in the pressure of underground gas reservoir. When the pressure is decreased to a point below the hydrocarbon dew point, there is condensation of the hydrocarbons like propane, butanes, pentanes and higher molecular weight hydrocarbons into the liquids. The formation of liquid hydrocarbons that takes place in a gas reservoir is known as retrograde condensation. It happens because some quantity of gas condenses into a liquid on decreasing the pressure under isothermal conditions. In order to resolve this, the dried gas is injected that helps in maintaining the underground pressure and allow the extraction of the gas from the condensed matter.


Conversion to CNG

There are many useful reasons for converting you r fuel source to CNG. The conversion is considered to be extremely safe when it is performed at a authorised government authorized retrofittment centre. It does not involve any sort of welding involved and there are no fundamental modifications to the body structure of the vehicle. One major benefit of the conversion is that the petrol option is retained thereby; you can even use the gasoline in case you are not getting the CNG refilling in time. It also helps during your travel outside your town where there would not be CNG refilling stations because petrol can be used in such conditions. Thus, you can travel irrespective of CNG / LPG availability along the route. Another benefit of conversion is that it helps you in making lots of savings.

The cost of the complete CNG kit and installation is around Rs 40,000 over the cost of the car. In case, you cover 10 to 20 Km daily, it does not worth purchasing the CNG kit. The CNG retail cost is approx Rs 22 per kg in Mumbai. You can make savings by using CNG only if you drive on average of 40 to 50 km every day and use it for a period of at least two to three years. In fact, the more you drive by using CNG, more you will recover on your investment. Conversion to CNG will require a boot space in car and it affects the degree of performance by small margin.

The conversion is recommended if the fleet owner wants to use your CNG Lancer, Optra, Indica etc, as a taxi. It helps in recovering the costs quickly. It is also useful if car covers at least 50 km a day. One major drawback for CNG is that you need to stand for an hour or two frequently to queue up behinds rickshaws and cabs for filling the gas. If the CNG outlets are not available in your region then you should not go for the conversion because the CNG infrastructure is not widespread in many places of the country.