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Development of CNG Infrastructure in DELHI (India)




(Metric Tonnes per Day) 



With the increasing number of pollutants in Delhi’s air and with the background of increasing trend in the use of CNG in the other parts of the world, Public Interest Litigation (PIL) was filed in the Hon’ble Supreme Court of India in 1985 seeking intervention in this matter. The Hon’ble Supreme Court had directed the Government of India to take initiative in promoting the use of CNG, an established clean fuel in the world as transport fuel in Delhi to control the increasing levels of ambient air pollution. 


Formation of IGL:

·  Supreme Court gave directive to GAIL in July’1998 to expand theCNG infrastructure and to increase the number of CNG stationsfrom 9 to 80 by March 31, 2000 in Delhi. It also directed Delhi convert entire city bus fleet, autos & taxies from liquid fuel toCNG/Clean Fuel.


·  Subsequently in Dec.1998 Indraprastha Gas Limited (IGL) was incorporated as a joint venture company of GAIL, BPCL & Govt. ofNCT of Delhi to regard to the CNG expansion program in Delhi. 

·  Issues of land allotment: Govt. of NCT of Delhi holding 5% equity in IGL helped IGL in getting the allotment of lands, permissions for laying pipelines and in getting electricity connections.

·  Uncertainty on vehicles conversion: While IGL was formed to install 80 CNG stations there was an apprehension whether the DTC buses would be available for CNG usage. Besides all the autorikshaws, taxis and private buses were also to be converted for CNG use. Tremendous efforts were required to convince DTC, Bus Operators and Delhi Administration for the conversion of vehicles to CNG in such a short time. Today there are more than 87,000 vehicles in theNCT of Delhi, which are running on CNG.


 Type of CNG Stations:

Four types of CNG stations have been developed in Delhi. These are as follows:

Mother Station: Mother stations are connected to the pipeline and have high compression capacity. These stations supply CNG to both vehicles and daughter stations (through mobile cascades). Typically they have the facility of filling all types of vehicles – buses/autos/cars. The Mother station requires heavy investment towards compressor, dispensers, cascades, pipelines,tubing etc.







Online Station: CNG vehicle storage cylinders need to be filled at pressure of 200 bars. “On line Stations” are equipped with a compressor of relatively small capacity, which compresses low pressure pipeline gas to the pressure of 250 bar for dispensing CNG to the vehicle cylinder. The investment in an online station is midway between daughter station and mother station.


Daughter Station: The “Daughter Stations” dispense CNG using mobile cascades. These mobile cascades at daughter stations are replaced when pressure falls and pressure depleted mobile cascade is refilled at the “Mother Station”. The investment in a daughter station is least among all types of CNG stations

There is reduction in storage pressure at daughter stations with eachsuccessive filling. Once the storage pressure drops, the refueling timeincreases, while the quantity of CNG dispensed to vehicle also decreases.


Daughter-Booster Station: Installing a booster compressor can eliminate drawbacks of daughter stations. The mobile cascade can be connected to the dispensing system through a booster. Daughter booster (compressor) is designed to take variable suction pressure and discharge at constant pressure of 200 bars to the vehicle being filled with CNG. The investment in daughter booster station is slightly higher than that of

daughter station.






Mega CNG Stations:

Mega CNG stations have been conceptualized to cater to a large fleet of

vehicles, particularly the buses. The objective is to provide comfortable filling experience to the consumers when they come to the station forefeeling. Mega CNG stations are constructed on much larger plot of land than that of conventional CNG stations, as a result of which more number of Compressors and Dispensers can be installed and more number of vehicles can be simultaneously refuelled at such stations. A Mega CNG station has been commissioned at Rohini, Sector 23 on July 13, 2003 and a similar station has been put into operation at Patparganj on June 30, 2003.At present, there are three Mega CNG stations in Delhi. The CNG Mega station at Patpargang has been constructed at a cost of around Rs.13.5 crores (USD 3 MM) to simultaneously refuel five buses and eight other vehicles (cars, autos, mini buses etc.). Built on a plot of size 75m X 40 m, it has the capacity to comfortably refuel CNG to 800 buses and over 1500 other vehicles daily.



The growth in the CNG infrastructure and the performance of IGL since it’s inception in December, 1998 is presented in the following bar charts:

Growth in CNG vehicles:


Growth in CNG Sales 




 YEARS* upto 31-12-04


Geographical Distribution of CNG stations

(As of 01st January 2004)                                                                                                             








Economics of CNG

The growth of CNG vehicles in the year 2002 was primarily because of economic advantage of CNG with regard to petrol / diesel. The economics of running the CNG vehicles vis-à-vis its operation on petrol /diesel has been worked out at the current price of fuel. The results are reproduced in the form of the following bar graph:



Cities where City Gas Distribution Projects being planned:


As per the directive of the Hon’ble Supreme Court of India dated April 5,2002, in order to control heavy air pollution due to vehicular traffic, the following cities in India have been identified for developing infrastructure for distribution of alternative fuel:


However, the study of air pollution indicated that the pollution in the cities of Jodhpur and Jharia is mainly due to dust pollution than vehicular emissions. Also, there are no trunk gas pipeline in the vicinity of Patna and Varanasi.

Subsequently, in August 2003, Hon’ble Supreme Court of India has issued a directive to the Union of India and the state governments to draw plans to introduce clean fuels in 11 cities apart from the existing cities of Delhi and Mumbai. These are:


Under its Project Blue Sky, GAIL has already drawn plans to implement city gas projects in the five cities of Kanpur, Lucknow, Agra, Bareilly and Pune in phases at an estimated investment of Rs. 554 crores (equivalent to 118Million USD). 






The total no. of CNG stations planned to be operational by the end of financial year 2003 – 2004 would be as follows:-


1) Delhi                           : 120

2) Mumbai, Maharashtra: 88

3) Gujarat                        : 6


Factors Influencing the Success of CNG Project:

· Government commitment to the program

· Sustainable economic advantage over liquid fuels

· Appropriate CNG technologies

· Appropriate program management

· OEM support

· Safety of CNG vehicles and CNG economic are key factors that determine the success of CNG program


Environment and Climate Protection


In India a new Auto Fuel Policy has been adopted in October’03 and the policy gives a roadmap for achieving various vehicular emission norms over a period of time and the corresponding fuel quality up gradation requirements. While it does not recommend any particular fuel or technology for achieving the desired emission norms, it suggests, taking into account security of supplies and existing logistics, perspectives, that liquid fuels should remain as main auto fuel through out the country and that the use of CNG/LPG be encouraged. The report also recommends measures for improving the present mechanism of checking pollution for min used vehicles.


·  Limited natural gas allocation leading to delay in management decisions onexpenditure commitment

·  Uncertainty about conversion of vehicles & CNG demand

·  Lack of indigenous technology

·  Capital intensive project - a mother station cost would be 5-6 times the cost of a petrol pump & pipeline need to be in place

·  Infrastructural constraints (Electricity, land etc.)

·  Delay in getting permissions from statutory authorities

·  Objection from local people, encroachment

·  Low storage capacity of on board cylinders, thus requiring frequent refills


Difficulties For Developing CNG Infrastructure

·  Limited natural gas allocation leading to delay in management decisions on expenditure commitment

·  Uncertainty about conversion of vehicles & CNG demand

·  Lack of indigenous technology

·  Capital intensive project - a mother station cost would be 5-6 times the cost of a petrol pump & pipeline need to be in place

·  Infrastructural constraints (Electricity, land etc.)

·  Delay in getting permissions from statutory authorities

·  Objection from local people, encroachment

·  Low storage capacity of on board cylinders, thus requiring frequent refills


The following difficulties are faced in developing CNG infrastructure:

The roadmap for vehicular ignition norm for new vehicles would be as




Lessons Learnt in Implementing CNG Program


IGL in a short span of five years has installed 117 CNG stations in NCT of Delhi in spite of various hurdles faced during implementation of the program. The following lessons have been learnt in implementing the CNG infrastructure development program:


·  Study of geographical spread of CNG vehicles movement is a must to analyze the peak demand at individual CNG stations

·  Pipeline distribution infrastructure needs to be in place

·  Dedicated/adequate mobile cascade filling arrangement continuous supply of gas to daughter stations.

·  Involvement of local government/transport authorities

·  Genuine cylinder kits and spare parts be used for CNG vehicles to avoid accidents

·  Suitable codes/standards are to be in placed for CNG kit fitment, testing etc.

·  Safety and performance standards should be in place, monitored and enforced

·  CNG stations need to be built in large open space to allow multi vehicle and multi point dispensing

·  Development of CNG infrastructure needs to be in line with growth of CNG vehicles.

·  Long term advance planning needs to be carried out

·  Development of CNG station is time and d capital consuming activity.



Compressed Natural Gas has been accepted as an alternative fuel by the public at large. The stage is set for expanding the network to other cities. The success of CNG Expansion Program would depend on many factors. The key factors being the economy of CNG vis-à-vis other conventional fuels, adherence to safety guidelines and the Government Support. Auto LPG is also launched on a large scale in the country. At the end of the day, it will be the quality of the fuel and economics which would beimportant parameters for the commercial success of auto fuel. The emphasis would be on fuels with lowest emissions. However, CNG is here for the time being till a better fuel is discovered offering better economics

to the users.



   With the price of petrol currently at Rs 49.78 per litre in Mumbai, the petrol Omni with fuel efficiency of 16kmpl, costs about Rs 3.11 to run per kilometer. The gas powered van travelled 18.48km to a kg. CNG per kg costs Rs 21.70 in Mumbai  which translates to about Rs 1.06 per km. So the CNG user is shelling out only half the cost of what a petrol-vehicle user does. Economical, for sure! CNG by virtue of being a gas is able to improve the combustion process by completely mixing with air, lesser scope of adulteration keeps the gas clean and ITee of impurities and better burning properties. This by itself improves the efficiency of the engine however kit installers also detune the engine so that it leans more towards the economy side rather than power.


Currently the priority before one indulges in the CNG driving experience means seeking the nearest CNG outlet with the shortest refuelling queue. Production has increased, distribution

has improved, storage is better, but the refuelling lines have not disappeared, though they are

not endless as they used to be.


Mumbai's largest CNG filling station near Sion is also the hub that supplies CNG all over the city. Being the main station, pressure is higher than elsewhere. This means you can pack in a few more kilos of gas into your canister for a few more kilometers before refill. Taxi drivers get their refills at such depots only so one must be prepared for a couple of hours of waiting. However do not be put off by the long queues as these are for cabs. For private vehicles there is another queue so one can drive in and get a refill most times without hours of waiting.


The need of the hour then is to increase the number of filling stations as the existing ones are woefully inadequate to cater to growing numbers of CNG users. Also, CNG use is still confined to the metros and smaller towns have been completely ignored. And with CNG being proved as safe for use as petrol, the path is clear for a mass move to switch to CNG as viable alternative fuel.





No. of CNG Vehicles Mumbai -151262 nos.



1721 nos.

3 wheelers

99,207 nos.

Transport vehicles

BEST buses

145 nos.

Pvt. Buses/mini buses

140 nos.


1082 nos.


460 nos.


48,507 nos.


151262 nos.


Thane - 7006



75 nos.

3 wheelers

6645 nos.

Transport vehicles

Pvt. Buses/mini buses

9 nos.


156 nos.


112 nos.


7006 nos.


Mira Road 


3 wheelers

1224 nos.


1224 nos.


No. of CNG Outlets - 110


4 nos.

Online stations

94 nos.

Daughter booster stations

12 nos.


115 nos.


Thane - 4 outlet (Online)

Mira-Bhayander - 1 outlet (Online)

Total installed compression capacity

13,63,200 Kgs/day


12,95,200 Kgs/day


51,000 Kgs/day


17,000 Kgs/day


Dispensing Points 564 nos.

(Mumbai - 536; Thane - 24; Mira-Bhayander - 4)

Average total Pollutants reduced - 510 tonnes per day

Steel Pipeline laid - 186.44 Kms

(Mumbai - 167.24 Kms; Thane - 12.56 Kms; Mira-Bhayander - 6.64 Kms)

PE Pipeline laid - 1710.08 Kms

(Mumbai - 1678.47 Kms; Thane - 15.03 Kms; Mira-Bhayander - 16.58 Kms)


Operating cost for a typical taxi

Rs 1.0 to 1.2 per km*

Operating cost for a typical auto

Rs 0.35 to 0.50 per km*

Operating cost for a typical bus

Rs 5.5 to 6.5 per km*


  • - depends on condition of vehicle, driving habits etc.

    ** - approximate only. To check with CNG retrofitters.

Safety aspect

Safety is of paramount importance to MGL. CNG is delivered to vehicles having CNG cylinders, which are approved and are within the periodic test life.

Identification labels (metal plate) are provided by MGL and installed in CNG vehicles near the refueling valve after the vehicle owner has got certification from RTO & necessary endorsement on RC book.

Every dispensing operator is trained and have been instructed to dispense gas to only those vehicles who have a valid metal plate.


Present retail selling price

Rs. 19.71 per kg

Operating cost for a typical taxi

Rs 1.0 to 1.2 per km*

Operating cost for a typical auto

Rs 0.35 to 0.50 per km*

Operating cost for a typical bus

Rs 5.5 to 6.5 per km*


-         depends on condition of vehicle, driving habits etc.



Approximate cost of CNG conversion of LMVs (taxi / Pvt. car - petrol driven)

Rs. 32,000/-**

Approximate cost of CNG conversion of Auto - petrol driven

Rs. 23,000/-**

Approximate cost of CNG conversion of in-use diesel buses / tempos

Rs. 3.5 to 4.5 lacs**


** - approximate only. To check with CNG retrofitters.








The demand for petroleum products in India has been increasing at a rate higher than the increase in domestic availability. At the same time there is continuous pressure on emission control through periodically tightened regulations particularly for metropolitan cities. In the wake of this situation there is an urgent need to promote use of alternative fuel as substitute for HSD. Among the options Compressed Natural Gas has received a great deal of attention and has been already applied successfully to some of the BEST buses (first time in India). The BEST is planning to increase the strength of CNG buses in its fleet.

  CNG can be used in the existing SI/CI engines with minor modifications.

  Availability in abundance.

  CNG is a clear burning fuel, with no black smoke and very low particulate emissions. Thus CNG engine is environmental friendly.

  CNG being lighter than air, diffuses upwards.

  CNG is very safe fuel due to its very narrow flammability limits.

  Excellent knock resistant, lower compression ratio. Lower rates of pressure rise and low peak cylinder pressures.

  Low noise level of the engine. This will add to passenger comfort. 


What’s different about CNG against other gases which are in use currently?
In the past, gas-fuelled automobiles used LPG (Burshane). Today it is compressed natural gas (CNG) that is in use. Methane is the prime component of CNG while LPG is a blend of propane, butane and some other chemicals

Can an existing LPG vehicle run on CNG?

An LPG-fuelled vehicle will not run on CNG as the two fuels are different from each other, have differing calorific values and need different air-fuel ratios for combustion. CNG has to be stored at relatively higher pressure in a cylinder than LPG, so the same cylinder cannot be used for both gases. A vehicle will need specific conversion for CNG operation.

Will my car still run on petrol if I run out of CNG?

The petrol carburettor is retained during conversion for CNG so that the vehicle will still run on petrol. A switch on the dashboard allows one to make instant changes of fuel sources.

How much will I save on CNG?

Savings on fuel cost by using CNG will depend on size and fuel consumption characteristics of the vehicle, as well as mileage. As we have seen in the CNG Omni the cost per kilometre incurred was nearly half that of the costs incurred by the petrol van.

Should I use petrol occasionally?

Occasional use of petrol serves to lubricate the carburettor besides making for better running of the engine.

Is the CNG option safe?

Four key features make CNG a safer fuel than petrol, diesel or LPG. With specific gravity of 0.587, it is lighter than air so in case of leaks, it rises up and dissipates into air. (Other fuels form puddles on the ground in case of leaks.) CNG has a 700 degree Centigrade ignition temperature compared to 455 degree Centigrade for petrol. The range of 4 to 14 per cent in which CNG mixes with air by volume for combustion is small. Storage is far safer than for petrol, as CNG cylinders are designed and built from special materials and to high safety specifications.


What is the pressure of CNG in a cylinder?

CNG is filled to a maximum of 200kg/cm (about 3000psi/g) in a cylinder.


Is refuelling cylinders a safe option with such high pressures involved? Is it safe even in an accident?

Refuelling is safe as the cylinder is made from a single piece of special steel alloy, with no welded joints, and each cylinder is tested as per international specifications before being installed. A ‘burst’ disc ensures safety as in case of inadvertent high pressure filling, or fore, the disc ruptures so no excess pressure situation over the specified level is created. Italy, New Zealand, Argentina and the US are countries where CNG has been in use for years, and it has been categorised as being safer fuel than petrol.

Will CNG harm my engine in any way?

Use of CNG serves to extend life of lubricating oil as CNG will not contaminate or dilute crankcase oil. Fouling of plugs is eliminated and plug life is enhanced as CNG does not contain any lead. CNG enters the engine as gas while petrol comes in as spray or mist which washes down the lubricating oil from the piston ring area to raise the rate of engine depreciation. This reduces maintenance costs and engine life goes up.

Why are exhaust gases literally non-existent in CNG vehicles?

A major positive aspect of CNG use is that being a natural gas (methane content) its exhaust emissions contain just water vapour and minuscule quantity of carbon monoxide, no carbon or other particles. Being virtually pollution free CNG driven vehicles meet the most stringent of emission standards world wide.


How does a CNG vehicle compare to a petrol powered one on performance parameters?

Easy starts, steady idling and smooth acceleration are virtues of CNG run vehicles. Power loss of 5-15 per cent means that acceleration is slower, which can be eradicated with spot-on tuning of the CNG kit, by advancing spark timing to derive benefit of its high octane rating. However the power loss is less than noticeable in city driving.

Does CNG equipment require special service?

The CNG kit is easy to service and durable to boot. For optimum efficiency regular checks, every 10,000km, are prescribed.

Can diesel vehicles be converted to CNG?

Yes, diesel vehicles can be converted to CNG and most public transport in metros which previously ran on diesel now use CNG.


Has the CNG movement fared well in developed or developing countries?

Having been around since the 1920s, Italy has 240 stations and 300,000 cars running on CNG, New Zealand has 250 CNG pumps and 250,000 vehicles. Argentina has undertaken a major CNG programme and has 700,000 CNG run vehicles. Thailand, Indonesia, Bangladesh, Canada, France, Pakistan, India, Holland, Australia, UK and the US have also taken to CNG in smaller measure. Availability of natural gas and socio-economic conditions are the two factors conducive to bring about switch to CNG fuel.

How does a country benefit if CNG were to be used on a large scale?

A country can have cleaner environment with comprehensive use of CNG, while new job opportunities and economy are other benefits of using CNG. Motorists will have to pay lesser for fuel and certain countries like India which has huge reserves of CNG can also export it to generate revenue. This will also reduce the expense of fuels we have to import.


IN a bid to encourage cleaner fuels the government has been promoting CNG and LPG as alternatives to conventional fuel (petrol and diesel). And with the public transport in the capital and other metros already running on CNG, the problem of limited refuelling outlets too seems to be disappearing. All this and the fact that green fuels mean lower running costs compared to conventional auto fuels, has a significant number of private vehicle owners interested in the CNG option.

To assess the cost factor, for a car like the Premier Padmini, a kilogram of CNG costs round about Rs 20 and offers a range of almost 20km per kg translating into running cost of rupee a kilometre. On the contrary, a litre of petrol, which costs about Rs 35, offers a running cost of almost Rs 3 per kilometre.

Even if we were to keep the better economy factor aside, CNG still offers a number of benefits. The fact that CNG enters the engine in the form of gas instead of spray or mist prevents the wash down of the lubricating oil from the top piston ring area keeping the engine’s rate of depreciation to a bare minimum. In addition, the octane number of CNG being 130 as compared to 87 of that of petrol helps thorough and rapid mixing of gas and air in the correct proportion, thereby improving the combustion efficiency.

Talking about good conversion systems, it’s imperative that the system operate as close to petrol as possible. In addition the risk of leakage should be marginal. So how much does a good conversion system cost? It can cost from around Rs 35,000 for a carburetted engine to Rs 45,000 for fuel injected ones (installation costs included). For taxis though it’s available on a discount at Rs 32,000 while for three-wheelers the price touches Rs 25,000. Most of these kits sold in India are brought in from Italy, while the remaining are manufactured in Gujarat.

A CNG kit includes a conversion kit and cylinder wherein the former is placed in the engine bay while the latter goes into the boot. The kit may be installed at any of the authorised CNG workshops,  which are increasing by the day. But attention must be paid to the safety aspect while installation, which takes a simple soap test to ascertain if the safety aspect is adhered to. The test involves covering the lines carrying CNG with a soap solution, which indicate a leak by forming bubbles at suspect areas.

The basic components of a conversion kit include a pressure regulator to provide the system with fuel at a consistent operating pressure in addition to a mixer to ensure correct air/fuel mixing in both stationary and dynamic conditions improving the drive of the vehicle thanks to improved mixing. Besides a high pressure solenoid to allow the flow of gas and a petrol solenoid to cut off the flow of petrol to the engine during gas operation.

A filling valve installed in the engine compartment between the storage cylinder and the regulator aids easy refilling. The valve is connected to the refuelling system and a manual ball device to open/shutoff gas in case of an emergency or for maintenance.
In the case the car runs out of gas, a change over switch is provided which is an electronic control module allowing the user to switch to petrol. The gas from the cylinder goes to the engine compartment through a pressure pipe, which is also connected to the refuelling system. It is all part of the high pressure piping system that works overtime to avoid leakage. A pressure indicator is also provided to display the level of natural gas remaining in the storage cylinder.

Installation of the CNG kit in a three-wheeler, and a taxi refuelling at a CNG station. Though refuelling takes just a few minutes the wait can be arduous. The three major parts employed for a CNG kit installation: mixer employed for correct air-fuel mixture, filler valve, cylinder in the boot.

In diesel engines, CNG can be used either as a dual fuel or mono fuel. In dual fuel mode, diesel provides combustion initiation for CNG burning. Kits can be retrofitted to existing vehicles for them to operate on diesel/CNG mode. However, under city driving conditions, the substitution of diesel with CNG is quite low and hence the gains in emission reduction are also low. Considering the limitations of emission reduction in a dual fuel engine, CNG can be used as a mono fuel by converting the diesel engine to a spark ignition engine. This conversion warrants major changes in the engine and the operation of the vehicle becomes CNG-dependent.

Safety aspects

Pressure vessels, in this case the storage cylinder, are ideally made of high strength steel or aluminium over wrapped with a composite material like fibre-glass. There have been reports of tank rupture upon refuelling due to the damaged fibre over-wrap thanks to the use of spurious cylinders, especially by unauthorised agents who carry out conversions from petrol to CNG. But this problem can be addressed through adequate monitoring and implementation efforts. CNG calls for high-pressure on-board storage of the fuel around 200 atmosphere (3000 to 3500psi) or more. Providing them as after-market retrofits on autos and cars without prope inspection would lead into disastrous results from the safety point of view.



sources of information:

NIKHIL NIGAM(Asst. manager MGL) 


 Environmental aspects of energy use in large Indian metropolises

New Delhi: Tata Energy Research Institute. 207 pp.

TERI. 1999

TERI Energy Data Directory & Yearbook 1999/2000

New Delhi: Tata Energy Research Institute. 452 pp.

 TERI. 2000

Restructuring options for the Delhi Transport Corporation

New Delhi: Tata Energy Research Institute. 89 pp.

 TERI. 2000a

Developing a sustainable and environmentally sound transport system for Delhi

New Delhi: Tata Energy Research Institute. 239 pp.


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