CNG conversion: Learning from New Delhi

Submitted by da_partner on Mon, 2006-01-23 17:34.



Govt of Delhi

During the 70’s and 80’s Delhi, the national capital, saw an unprecedented growth in population, vehicles and small scale industries, which caused serious ecological imbalance and environmental degradation. The problem got further aggravated by increasing migration from neighbouring states. The total area of NCT of Delhi is 1483 sq. Km with an urban segment of 685.34 sq. Km in the year 1991. Urban population grew at 51.53% from 1991-2001 as compared to 46.89% during 1981-1991. The density of the population also increased to 9294 persons per sq. Km (the highest in the country) in the year 2001 against 6352 persons per sq. Km in 1991 (Source : Economy Survey of Delhi, 2001).
Delhi, in terms of air pollution, was ranked fourth among the 41 most polluted cities in the world, in the 90’s. The period between 1989 – 1996 saw a rapid increase in pollution levels. Infact, 1996 is considered the peak year in terms of air pollution load. The transport, industrial and the domestic sectors were the major contributors towards the rising ambient air pollution levels, in addition to the presence of natural dust due to meteorological conditions. Figure 3 indicates the contribution from various sectors to ambient air pollution.

Vehicular Pollution  

 Delhi has experienced an exponential growth in the number of personalized vehicles over the last two decades. The rising trend in air pollution load from vehicular exhaust can also be noticed from the rise in the consumption of both major auto fuels i.e. petrol and diesel.

The contribution from the vehicular sector increased from 23% in the year 1970/71 to as much as 72% by the year 2001.The annual average levels of suspended particulate matter increased to 450 µg/m3 during 1996, which is nearly three times the National Ambient Air Quality Standard of 140 µg/m3 for residential areas as notified by the Ministry of Environment, Govt. of India. This rapid population growth along with the high rate of urbanization as also industrialization and an increase in motorized transport has resulted in an increase in the levels of various air pollutants, namely (1) Oxides of Sulphur, (2) Oxides of Nitrogen, (3) Suspended Particulate Matter, (4) Respirable Suspended Particulate Matter, (5) Carbon Monoxide, (6) Lead, (7) Ozone, (8) Benzene, (9) and Hydrocarbons.


The main source of vehicular pollution is the fuel itself. A part of mitigation measures started in 1996, with the introduction of reduced concentration of lead in petrol from 0.56 g/l to 0.15 g/l, reduction of benzene to 5 % and reduction of sulphur from 1.0% to 0.5%.
As a measure to counter the increasing air pollution load in Delhi, the Hon’ble Supreme Court passed the orders to move all the public transport on CNG by March 31, 2001.

Legal Aspect

The major decisions taken by the Judiciary since 1990 were instrumental in bringing about the conversion of public transport in Delhi from diesel to CNG. A chronology of major events is given as under:

1990 11 14

The Ministry of Environment and Forests (MoEF) submits an affidavit to the Supreme Court (SC) admitting that the heavy air pollution in Delhi is due to petrol and diesel operated vehicles in the area. The SC agrees and specifies that heavy vehicles in particular, such as buses, trucks, and military vehicles, are the main culprits. The Court asks the Delhi Government to produce details about prosecutions and suspensions that it claims to have administered to vehicles causing pollution. It also suggests that the MoEF look into catalytic converters, a device that is said to reduce pollution from vehicles (Writ Petition order dated 11/14/90).



The Supreme Court makes its first order to the Gas Authority of India, Ltd. (GAIL), the gas distribution arm of the Delhi government, to switch over to a clean fuel. It orders that at least five stations providing CNG should be set up, and that a minimum of 5 DTC buses should be converted to CNG.

1996 4 26

The Supreme Court agreed to a schedule to convert government cars to CNG on 03/28/95, but as of this date the schedule has not been followed. 720 cars should have been converted by now, but only 97 have. SC rules that, since all obstacles have been resolved such as availability of conversion kits and location of a Mother Station, 720 Delhi government vehicles must either be fitted with a catalytic converter or be converted to CNG by the end of August. The catalytic converter option is made available because it may be more economical. The remaining 540 cars of the total fleet of 1,260 must be fitted or converted by October. The SC orders the Ministry of Surface Transport (MoST) and MoEF to ensure that the conversions happen on time (Writ Petition Order dated 04/26/96).

The Supreme Court agreed to a schedule to convert government cars to CNG on 03/28/95, but as of this date the schedule has not been followed. 720 cars should have been converted by now, but only 97 have. SC rules that, since all obstacles have been resolved such as availability of conversion kits and location of a Mother Station, 720 Delhi government vehicles must either be fitted with a catalytic converter or be converted to CNG by the end of August. The catalytic converter option is made available because it may be more economical. The remaining 540 cars of the total fleet of 1,260 must be fitted or converted by October. The SC orders the Ministry of Surface Transport (MoST) and MoEF to ensure that the conversions happen on time (Writ Petition Order dated 04/26/96).


1997 1 20

The Delhi government decides to introduce new emission norms in the capital in 1998 to control pollution. Three specific measure are to be implemented immediately. One, all vehicles fitted with two-stroke engines will be banned. Two, the use of propane in all three-wheelers will be mandatory from April of this year. Three, all vehicles running on diesel must be fitted with a "diesel converter." These measures are announced after the Delhi government gets approval from the Union government to introduce new emissions norms by 1998 instead of 2000. According to Delhi's minister for transport, Rajendra Gupta: 'We made the request in an effort to
equip the Delhi government with the powers to honour the Supreme Court directives on reducing pollution in the Capital.' Mr. Gupta also asserts that the government recognizes that vehicles contribute to 64% of the total pollution figures in Delhi. He says the Delhi government also plans to examine the introduction of electric trolley service on an experimental basis, import buses from the US which will run on fuel cells, and design an "outer ring" bypass road around the city (The Business and Political Observer, 01/20/97)


1998 8 22

India's first CNG bus is launched in Delhi. The bus is run by DTC on a trial basis (Statesman--New Delhi, "Capital's First Pollution-Free Bus," 08/22/98).


1999 2 8

The Delhi Cabinet constitutes a committee headed by the Chief Secretary to devise the implementation of restrictions imposed by the SC. Delhi Environment Minister, A. K. Walia, says that most autorickshaw and taxi drivers come from the lower classes, and can not afford the cost of replacing their vehicles. Currently, CNG is available at nine dispensing stations in the capital (Statesman-- New Delhi, "Panel to Chalk Out Implementation Plan," 02/09/97).


1999 4 14

Ashok Leyland offers to supply CNG buses to the Delhi government. The CNG engines would cost an additional Rs 300,500 per unit. Ashok Leyland has also offered to help convert existing buses from diesel to CNG (The Observer of Business and Politics, "Ashok Leyland to Supply CNG Buses to Delhi Govt," 04/14/99).


1999 4 16

The SC amicus asks that the respondents (parties involved) suspend registration of diesel vehicles until further orders. The court asks for the Additional Solicitor General to submit an affidavit about the number of diesel and petrol private vehicles, including disaggregated stats for two- and three-wheelers, registered in NCR in 1997, 1998, and the first three months of 1999. The information will help determine whether the amicus' plea should be granted. The amicus receives an application from DTC for clarification of the 07/28/98 direction and one from the Union of India seeking an extension for implementing unleaded petrol throughout the country (Target 3, Phase 3) and for converting old vehicles in Delhi to CNG. The amicus also requests some information from the Municipal Corporation of Delhi and the Deputy Commissioner at the Traffic Division of the Delhi Police and asks why they have not been complying with earlier directions, specifically the one from 12/16/97 (Writ Petition Order dated 04/16/99). The counsel for Telco, F.S. Nariman, tries to stall the looming ban on diesel by claiming diesel cars make up a small percentage of cars on the road in Delhi. His comment prompts the SC to request more statistics as explained above (DTE, 05/31/99).


1999 6 1

The Chief Secretary of the Delhi Government, Nomesh Saigal, announces that all 7,500 DTC buses plying in the capital will be converted to CNG by March 31, 2001. He also says that the State Government is planning to allow 2,500 new CNG buses owned by big transport operators to ply in Delhi. He states that only CNG three-wheelers will be allowed to ply in Delhi after March 31, 2000, but adds that new three-wheelers would be given an additional year for the changeover (The Observer of Business and Politics, "DTC Buses to be CNG-Driven by 2001," 06/02/99). These policies are a result of the recent SC directives. Another source reports that Mr. Saigal says the Delhi Government will propose a ban on two-stroke two-wheelers and will ban the conversion of private vehicles from petrol to diesel. Additionally, only four-stroke two-wheeler sales and registrations will be allowed in the NCR from March 31, 2000 (Statesman--New Delhi, "Diesel Buses, Taxis to be Banned in NCR," 06/02/99).


1999 8 21

In an update on the status of CNG buses in Delhi, Delhi Chief Minister, Sheila Dixit, states, 'The Telco bus, which is slightly better than Ashok Leyland's, will continue on trial run for a month or two before a final decision is taken.' There have been complaints that the CNG bus cabins have become very hot on Ashok Leyland buses, but the Chief Secretary of Ashok Leyland says that Telco buses are only slightly better in this regard. Dilip Biswas states that CNG engines are known to produce more heat, which means that bus engine cooling systems need to be modified to cope with overheating (Business Line, "'Efforts to Run CNG Buses Successfully,'" 08/22/99).


1999 10 1

Diesel with 0.25% sulfur content will be available across India as of this day (DTE, "Cheap Fuel, High Cost," 02/15/99). (Another Down To Earth article from 02/28/99 titled, "Better gasoline grade," claims that such diesel became available across India on 01/01/00).


1999 11 19

An article reports considerable confusion over the number of CNG buses currently operating in Delhi. DTC claims to have put 11 buses on the road, including nine Ashok Leyland CNG buses and two converted buses. Delhi Transport Minister Parvez Hashmi claims there are 15. Technical experts, however, say there are only five running daily, the rest being experimental. IGL is  reluctant to increase the number of CNG stations until more buses are added, because it requires a huge investment. At present there are 12 CNG refilling stations, eight catering to cars only. Currently there is only one CNG station operating for use by buses (Indian Express--New Delhi, "CNG Bus Project Develops a Flat," 11/20/99).


2000 2

The Transport Ministry frames the first emission norms for CNG-vehicles. This occurs 19 months after the SC passed its 7/28/98 order (Telestsam). 12 CNG stations are operating in Delhi. IGL claims it will have 50 stations by March 2000 if all land and construction disputes get resolved (best case), 30 short of the deadline target (7th EPCA Progress Report Dated: December 1999
to February 2000).


2000 2 4

The Delhi Government clears a proposal to ban the registration of all commercial vehicles running on petrol or diesel, allowing only CNG-run vehicles to be registered from April 1, 2000. The Delhi Government also decides that from April 1, diesel-run vehicles would have to meet EURO II norms, and plans to restart the PUC program (with changes). The proposal is expected to soon be put before the Cabinet for formal clearance. Delhi Environment Secretary, Rajiv Talwar, states, 'The CNG and its effects on the environment can be debated later on. First we have to phase out the dangerous pollutants. Such a debate should not stop the introduction of CNG' (The Hindu--New Delhi, "Govt. Okays Pollution Panel's Ban Proposal," 02/05/00).


2000 2 13

A CPCB study shows that there has been a significant reduction in pollution at traffic intersections and in industrial areas in terms of CO, NO2, lead, SO2, and suspended particulate matter (The Hindu--Delhi, "Marked Drop in Pollution Levels," 02/14/00).


2000 3

MoST finally provides certification norms for converted CNG vehicles. Converted buses have been waiting since as early as April 1999 for permanent certificates to ply. Because the norms weren't issued until now, DTC stopped converting old buses (it successfully converted only 7 out of 1,800) and started ordering new buses. On top of being late, the norms are ambiguous; they
only state that CNG vehicles must conform to the existing Euro emission norms meant for petrol and diesel vehicles (DTE, "Abysmal Performance," 04/30/00).


2000 3 6

The Union Government "notifies" Bharat Stage II norms, which will come into force on April 1 this year. Bharat State II norms are the Indian equivalent of Euro Stage II norms. These new norms are stricter than the existing India 2000 norms and apply to the Indian driving cycle of 90 km/hr compared to the European driving cycle of 120km/hr. "The reference fuel for meeting the norms will be up to 0.05 per cent mass maximum sulphur content" (Business Standard, "Govt Notifies Indian Version of Euro-II Emission Norms," 03/06/00).


2000 3 15

Delhi Transport Minister, Pervez Hashmi, says that the Delhi government will approach the SC to have the April 1 CNG deadline extended by two years. They plan to cite the inadequacy of CNG filling stations and kits as the primary reason behind the delay. Sheila Dixit, Delhi Chief Minister, says that the city will have 82 CNG filling stations shortly. She also reports that they are having difficulty with the CNG buses; they placed an order for 100, but only received 10. She also reports that three of these ten buses have 'collapsed,' with the remaining seven being run on a trial basis (Asian Age, "Delhi Plans to Stop Private Diesel Vehicle Registrations," 03/16/00).


2000 4 1

About 1,800 buses (almost all); 17,000 rickshaws; and 1,200 taxis, all more than 8 years old, go off the road. Commuters panic and some are left stranded. The panic wanes, though, when the DTC sells off buses older than 8 years (DTE, "The CNG Sabotage," 03/15/01).


2000 5 10

The SC directs the central government to supply petrol and diesel with 0.05% sulfur content and 1% benzene content from June 2001 in the NCR. The SC directs MoPNG to supply petrol with 0.05% sulfur content in the NCR by March 31, 2000, to supply petrol with 1% benzene content in the NCT by October 1, 2000, and to supply petrol with 1% benzene content in the NCR by March 31, 2001. The SC also requests that MoPNG supply diesel with 0.05% sulfur content in the NCT by 12/31/00 and in the whole NCR by 06/30/01 (Economic Times, "Cleaner Fuel for NCR from June 2001," 05/11/00).


2001 1 27

The SC refuses to extend the March 31, 2001 CNG conversion deadline and blames the Delhi government for avoiding the order for two and a half years. Private bus operators tell the court that two converted buses failed on-road tests, but this was denied by the agency that had converted them. Private operators state that they need financial assistance from the government in order to convert to new CNG buses, but the Delhi government's counsel and additional solicitor general, Kirit Raval, states that 'the government is not in a position to give any financial assistance in this regard to private operators' (Times of India--Delhi, "SC Refuses to Extend
Deadline," 01/27/2001).

2001 3 26

In response to pleas for a more precise definition of "clean fuel" (mostly from the MPNG--DTE, 9/31/01), the SC asks the EPCA to collect various opinions and determine whether other fuels, particularly low (500 ppm) and ultra low (10 ppm) sulphur diesel, should be considered in addition to CNG for vehicles (Writ Petition Order dated 3/26/01). The Court grants a temporary extension for the CNG conversion of buses until the end of September 2001 for groups that have ordered CNG buses and are awaiting delivery, especially those that supply school buses (Writ Petition Order dated 3/26/01). For example, DTC has placed orders for 1,880 new CNG buses, so it is allowed to run that many diesel buses until either the orders are filled or September 30 arrives, whichever comes first (DTE, "Key Points of the March 26 Ruling," 4/30/01). The Delhi Transport Department is held personally responsible for making the extension a success. Ashok Pradham must ensure that only people who have placed an order for a CNG-engine are allowed to drive their diesel bus after today. He must sign a sticker to be placed on the windshield of eligible buses only. Furthermore, the SC extends its order and requires all commercial vehicles, not just buses but taxis and autos as well, to be converted to CNG (Telestsam).


2001 7 14

700 DTC buses, 620 private buses, 22,575 three-wheelers, 870 rural transport vehicles or light commercial vehicles, and 12,790 cars and taxis are relying on CNG for fuel (12th EPCA Progress Report Dated: June and July 2001).


2001 9 28

The SC extends the deadline for CNG-only buses to October 18, 2001. Ambulances, diagnostic vehicles, and jail vans are exempted from the norm. The relaxation of the deadline is contingent on Center and Delhi government steps to prevent the adulteration of diesel. The Court also issues directions to take against people who adulterate diesel and criticizes the inaction of the
Center and Delhi governments and IGL in meeting the deadline. The SC criticizes IGL for what it perceives to be divergent views on the availability and supply of natural gas. Sheila Dixit reports that Ram Naik, Union Petroleum Minister, tells her that there will be no queues for getting CNG from October 1. Finally, there is reported jubilation amongst transporters waiting outside the SC upon hearing the new deadline (Statesman--New Delhi, "SC Extends CNG Deadline to 18 Oct.," 09/29/2001).


2002 7 29

The SC directs, effective August 5, 2002, that no retro-fitted or converted CNG bus be allowed to ply until the Director of the Transport Department of the NCT of Delhi has certified and confirmed that the buses meet the safety requirements from November 19, 2001 (EPCA Response to IA 179, 94). New CNG buses would not come under this order, but it is estimated that 20-30% of the 10,000 city bus fleet would go off the road. The SC also criticizes IGL for long lines at CNG filling stations that appear to be lengthening over time. Chief Justice Kirpal states, 'If vehicles, after converting into CNG, do not meet the safety requirements as per the notification, there is no reason why we should allow unsafe vehicles to ply on Delhi roads.' Harish Salve also tells the SC that the hike in CNG prices does not appear to be justified (Business Line, "SC Tightens Safety Norms for CNG Buses," 07/30/02).


2003 1 2

An article reports that SO2 and CO levels in Delhi have dropped over the past year, but CO, SPM, and RSPM levels are still above permissible limits. The improvement in air quality is attributed to the adoption of cleaner fuels. In particular, the drop in SO2 is attributed to a reduction in the sulfur content of coal and fuels. It is not clear why CO levels have dropped. It is also reported that nearly all autorickshaws in the city have converted to CNG, but the increase in the overall number of two-wheelers raises concerns. SPM and RSPM levels have been constant over the three years, most likely because other factors besides automobiles influence the levels of these pollutants. The article also reports that all 8,000 buses in Delhi now operate on CNG (Indian Express--New Delhi, "Delhi Inhales Cleaner Air Now, Says CPCB," 01/02/03).


Fiscal Aspect


Some of the fiscal measures that were put in operation and some were recommended for making conversion to CNG a financially feasible option for all stakeholders.


Evoke polluter pay principle for emissions and congestion mitigation measures:

Following the Hon’ble Court’s order of April 5, 2005, for the first time in the country penalty was imposed on the basis of polluter pay principle, on diesel buses for violating the Court order and not moving to CNG. This penalty has generated a huge corpus of Rs 30 crore that is today available to the Delhi government to fund other emissions control measures in the city. This experiment demonstrates how it is possible to develop fiscal instrument for improvement of transport and technology to control emissions. This has been a pioneering effort and should build on to develop future fiscal policies in the city.


The Environment Pollution (Prevention & Control) Authority (also called as Bhure Lal Committee) set up during the conversion of public transport to CNG driven vehicles made few suggestions pertaining to designing policies to deal with the vehicular pollution:


 Delhi government be directed to design fiscal policies to check explosive rise in the numbers of private vehicles and submit a schedule for implementation: EPCA would like to emphasise the fact that this authority should focus on developing composite transportation policy framework to link transport planning with air pollution control strategies in the city. The immediate focus should be on augmentation of public mass transport integrated with flexible feeder service, rationalisation of tax system so as to tax private modes of transport at a much higher level than public mass transport, annualisation of taxes paid by private vehicles based on kilometers driven, provision of incentives for cleaner modes of transport (cleaner fuels and vehicle technologies), and active encouragement of non-motorised transport.








Though the expansion of industry, trade and commerce have provided opportunities for economic development, but this in turn has transformed the character of Delhi from an administrative city to a multifunctional megapolis with a significant shift towards industry, commerce and services.

The objective of this whole exercise was:

·       To reduce the level of vehicular pollution in the city

·       To find out less polluting alternative to diesel

·       To work out a phased conversion of diesel run commercial vehicles to a less polluting fuel

·       To find out financially feasible option for diesel











It is a well known fact that polluted air is a symptom, not a cause. A part of mitigation measures to reduce vehicular pollution in Delhi started in 1996, with the introduction of reduced concentration of lead in petrol from 0.56 g/l to 0.15 g/l, reduction of benzene to 5 % and reduction of   sulphur from 1.0% to 0.5%. Over the next four years, the quality of fuel further improved as explained in Table 2 with further reduction in sulphur in diesel and lead in petrol.

However, the factor that was instrumental for the conversion of public transport in Delhi to be CNG driven was a ruling by the Hon’ble Supreme Court.

On July 28, 1998, in an unprecedented development, the Supreme Court (SC) ruled that the total passenger bus fleet of Delhi be increased from the then figure of about 6,000 to 10,000 by April 1,2001 and the entire city bus fleet be converted to CNG. The objective was to expand the city's public transport system and also to control pollution. To deal with pollution from petrol-driven vehicles, the SC ordered the exclusive sale of unleaded and low benzene petrol and advanced improved Euro II vehicular standards by almost five years. By August 2001, Delhi had the largest fleet of CNG buses in the world. There were 2,394 buses, over 27,000 autos and 14,000 other vehicles running on CNG”.

This was based on the recommendations of Environment Pollution (Prevention & Control) Authority (EPCA), also known as Bhure Lal Committee, set up by the Ministry of Environment & Forests.


 From 1999 onwards, the Govt. of NCT of Delhi persuaded the Govt. of India for bringing converted CNG vehicles under permit and tariff jurisdiction of the Govt., for which an amendment had to be made in the Motor Vehicles Act during September, 2001.
The co-ordinated measures for affecting the switchover were put in place by the Govt. of Delhi through multipronged action as different agencies were responsible for ensuring the environment friendliness of public transportation namely Delhi Transport Corporation (DTC), Indraprastha Gas Ltd. (IGL), Dept. of Transport, and Dept. of Environment.

In late 2001 the Delhi Govt. prepared a phase out plan for diesel buses, which was approved by the Hon’ble Supreme Court. Under this plan, 800 diesel buses per month were to be phased out every month between April, 2002 and November, 2002. Following this plan, the entire public city bus fleet was converted to CNG for which, Govt. of Delhi provided adequate funds.

Apart from buses, all pre-1990 auto-rickshaws were also to be replaced with new autorickshaws and post-1990 auto-rickshaws were to be retrofitted with CNG kits. Inspite of the constraints like non-availability of CNG autorickshaws and retrofitment kits, Delhi Govt. was instrumental in getting 47000 auto-rickshaws replaced. This was done by giving incentives like Sales-Tax exemption and interest subsidy on loans to the auto rickhsaw owners. Besides this, 2.4 million vehicles were checked for pollution during the year 2002-03.

With CNG accepted as an alternative fuel, the stage is now set for expanding the network to
areas bordering Delhi, comprising the National Capital Region (NCR). CNG is also the cheapest of auto-fuels, as per the prevailing prices in May 2003, CNG compares favourably with diesel and petrol. However, use of clean fuels by the public transport system is only a part of the solution.

The fight against air pollution in the capital, which began in right earnest in 1997, finally started yielding results. Statistics have shown that not only has the rising trend in pollution level been checked, but the level of various pollutants in the ambient air are also coming down. One of the renowned experts has stated, “What took 30 years to accomplish, we have done in 5 years.”   Though Delhi remains a polluted city, there is not much of chemical pollution. The period between 1989-96 saw a rapid increase in pollution levels. The Year 1996 may be considered as the peak year. But in the wake of use of CNG as an alternate fuel, the contribution of vehicular sector towards air pollution has been reduced in the subsequent years. This is also supported by the fact that there is a significant improvement in the air quality. The best place to witness this change is the busy ITO traffic intersection, where toxic fumes no longer irritate the eyes as earlier. Carbon Monoxide, Nitrogen Dioxide, Lead and Sulphur Dioxide levels have all shown a declining trend. The annual average of 42 mg/m3 of Sulphur Dioxide in the year 1996 came down to as much as 18 mg/m3 during 2002 at ITO Intersection, whereas NO2 came down from 75 mg/m3 in 1996 to 59 mg/m3 in 2000. Further, there has been a marked decline in the annual Lead levels after introduction of unleaded petrol in 1998. Also, the results show a significant improvement in the overall air quality of the city. The concentration of Carbon Monoxide has fallen by 32 per cent; Sulphur Dioxide levels have fallen by 39 per cent in 2002 as compared to 1997. The concentration of other pollutants like Lead and Benzene have also registered a marked decline. Despite the phenomenal growth in vehicular population, the levels of Nitrogen Dioxide have remained more or less constant, this can be attributed to the phasing out of old commercial vehicles and implementation of Euro-I and subsequently Euro-II norms for petrol and diesel driven private vehicles.




The key to the success of the CNG program for transportation in New Delhi was that there was a legal obligation requiring vehicles to use CNG. The Indian capital, New Delhi has succeeded in encouraging public transportation vehicle operators to use compressed natural gas (CNG) to reduce pollution and relieve dependence on more expensive gasoline and diesel fuels.

All public transportation vehicles -- buses, taxis and three-wheeled motorized taxis - in New Delhi started using CNG or other clean fuels in 2001, thanks to consistent law enforcement.

The drive began in mid-1998, when the Indian Supreme Court issued a directive obliging the state-owned Gas Authority of India Limited (GAIL) to increase the number of CNG stations from nine at the time to 80 as of March 2000. The directive also stipulated a time line for all programs that had to be carried out by both the country's central and state governments. The legal obligation also required all city buses running in the capital to be converted to CNG after there were an adequate number of CNG stations. Bus operators had four years to prepare for the conversion of their fleets.

Other directives were that no buses over eight-years-old were allowed on New Delhi's streets unless they were using CNG or other clean fuels and all pre-1990 taxis had to be replaced by new vehicles on clean fuel.

The major hurdle in the development of CNG was limited number of natural gas pipelines. To overcome the problem, a "mother-daughter" system was devised with four types of filling stations. At the "daughter stations", referring to stations where gas pipelines were not available, CNG is delivered via "cascades" (bundles of cylinders) attached to trucks. The cascades are filled up at the CNG stations, which are installed on gas pipeline. Then there are the "daughter booster stations". These are also stations that do not have access to pipelines. The only difference is that a variable suction pressure compressor (booster) is installed in-between the mobile cascade and the dispenser. The third ones are the online stations. Online stations are connected to the pipelines for continuous CNG supply. And finally, there are the mother stations. These stations are similar to the online stations in configuration. The difference is these also supply the mobile cascade trucks.

With the efficient system, New Delhi has been able to expand the number of natural gas stations and at the same time the number of CNG-powered vehicles continuously increases.
Recent data shows that there are over 150 CNG stations now in operation, while, the number of CNG-powered vehicles is at approximately 50,000.

Role of Government in developing a policy to control Delhi’s Pollution

On a formal level, during the mid to late 80s, the government enacted a great deal of environmental legislation and announced many initiatives. New legislation added the Environmental (Protection) Act of 1986, the 1987 Air act amended, the 1988 Motor Vehicles act, and the 1989 Central Motor Vehicle rules to the 1981 Air Act, which itself gave the CPCB authority to take a number of actions with respect to air pollution including to “lay down standards for the quality of air”. The 1988 Motor Vehicles act and the 1989 Central Motor Vehicles Rules gave the Government authority to set standards for vehicular emissions for manufacturers and users.
 In the mid-1980s, government initiatives at both the Central and Delhi level included a number of campaigns to educate Delhi residents about air pollution and to reduce vehicular pollution through both voluntary and nonvoluntary means, as well as a series of enforcement plans that would impose penalties.

Role of Judiciary in making conversion mandatory

Judiciary played a pivotal role in paving way for conversion of diesel run public transport vehicles to CNG. The Supreme Court, on November 18, 1996, issued an order on its initiative to the Delhi Government. The Court directed the Delhi authorities to submit a plan to control the city’s air pollution. The government’s response in an affidavit filed with the Court contained its first comprehensive plan, which included, among other items, recommendations to reduce the sulphur content in diesel and to encourage the use of CNG by building the necessary infrastructure and providing financial incentives.

Role of Civil Society and Stakeholders in creating an environment

Stakeholders included the NGO community, persons and groups in the affected industries affected in one way or the another by the Court’s orders, and the general public. In addition, politics and politicians played a significant role at various points.
Organised NGOs were prominent players in the issues before the Court. M.C. Mehta, the public interest lawyer who brought the ground breaking case that began this process, continued to play an active role for atleast 10 years. In the mid-1990s a NGO, CSE , took a prominent role, first by publishing a report that connected vehicular technology and maintenance , poor fuel quality, and traffic planning to the health impacts from Delhi’s high pollution levels.

This experience has shown that good transport planning and service integration is the essential prerequisite on which environmental improvement of bus services has been founded. There is no question that in cities with serious particulate air pollution and a large number of vehicles running on conventional diesel, replacing diesel with CNG can go a long way in reducing exhaust particulate emissions. The impact is immediate, as the experience in Delhi along high-circulation traffic corridors has shown. In generic terms, the lessons learnt were as follows


·       Need to involve all stakeholders in planning


·       Need to get prices and economic incentives right


·       Need to balance fuelling infrastructure with number of vehicles


·       Capital costs of underused infrastructure may not be recoverable in the fuel price


·       If fuel prices are right, vehicle owners will queue for natural gas fuel




The CNG conversion model has been a success in Delhi. Despite many hurdles, Delhi has shown that if critical instruments are supportive to the cause the task is not difficult to accomplish.  More specifically, the prerequisites for the Model’s applicability are

• Setting stringent emissions standards for vehicles on alternative fuels, whether new or converted
• Setting safety standards
• Allocating adequate natural gas for vehicles
• Formulating fiscal incentives to encourage all categories of vehicles to shift to alternative fuels.
• Availability of adequate  Dispensing stations
• Favourable  pricing policy- conducive both for State and private stakeholders

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  2. K K , Sruthijith ; “CNG: Environmentalism vs Economics”,  Centre for Civil Society
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  4. Ghose , Chandrachur ; “CLEAN AIR: THE DELHI EXPERIENCE” -Right To Clean Air Campaign; Centre for Science and Environment, 8th National Clean Cities Conference, Oklahoma City, May 14, 2002
  5. Bell, Ruth Greenspan ; Mathur , Kuldeep ; Narain , Urvashi ; Simpson , David., “CLEARING THE AIR: WHY AIR QUALITY REFORMS FINALLY TOOK HOLD IN “,