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Project report submitted is partial fulfillment of the    requirements for the award of degree of bachelor of management studies, Mumbai University.




                    Project submitted by:

                      Yogesh D Solanki

                 T.Y.B.M.S (V Semester)












        CHURCHGATE, PH. NO.:22818477



Transport plays a significant role in the overall development of a nation’s economy. However, this sector also accounts for a substantial and growing proportion of air pollution in cities. In addition, the sector contributes significantly to greenhouse gases emissions and is a major consumer of petroleum fuels.

According to recent WHO estimates up to one lakh people die annually because of the adverse effect of the air pollution. As per Central Pollution Control Board (CPCB) a nodal pollution monitoring authority in the country, automobiles contribute the highest amount of hydro carbon in the air as much as 81 % of the suspended particulate Matter (SPM).

Delhi, being one of the most polluted cities in the world, has reached frightening proportions with over 3000 metric tons of air pollutants emitted in the capital every day. Delhi figures in the list of six cities, which have acute air pollution problems. The other such cities are Mumbai, Kolkata, Nagpur, Ahmedabad and Kanpur.

Due to Projected increases in Gasoline/diesel vehicles use, even the strictest feasible emissions controls on petroleum fuel vehicles will not substantially reduce total emissions. The use of petroleum for transportation results in large quantities of pollutant emission from vehicles, refineries and fuel stations. Light gasoline vehicles are a major source of non-methane hydro carbons (NMHC) and NO the main prcusors in Ozone and the single largest source of CO. Heavy duty diesel vehicles are significant sources of NO. Particulate matter (PM) and SO. NO and SO can cause acute and long term illness and premature death, reduce agriculture productivity, damage materials, reduce visibility and contaminate ground water and coastal areas. Altogether, transportation continues to be a major source of toxic air pollutants in urban areas. Air quality is not likely to improve as long as petroleum is the primary transportation fuel. Methane hydro carbons (NMHC) and NO the main precursors in Ozone and the single largest source of CO. Heavy duty diesel vehicles are significant sources of NO. Particulate matter (PM) and SO. NO and SO can cause acute and long term illness and premature death, reduce agriculture productivity, damage materials, reduce visibility and contaminate ground water and coastal areas. Altogether, transportation continues to be a major source of toxic air pollutants in urban areas. Air quality is not likely to improve as long as petroleum is the primary transportation fuel.



Overview of the transport sector in India


In India, the share of the transport sector in GDP (gross domestic product) in 1997/98 was 7.3% (1993/94 prices). Road transport and the railways account for the majority of this contribution. The transport sector is also the second largest consumer of energy, next only to industry and commercial energy consumption about 98% of which is in the form of HSD and gasoline, grew at the rate of 3.1% per annum in the 1970s and at 5.6% per annum in the 1990s

The relationship between transport and emissions in India is established via the use of fossil fuels. The linkage between transport and the environment is particularly visible in the urban transport sector due to the dominance of road transport. In addition, the transport sector accounts for a large and growing proportion of Greenhouse Gas (GHG) emissions.


Gross carbon emissions from alternative

transport fuels



  The method used in this research has two main components. The first is an examination of each energy industry in detail, using primary sources of data from power stations, oil refineries and anhydrous ethanol production from molasses. The processes involved in each case are examined, taking into account energy use in any necessary auxiliary activities to evaluate the total carbon emissions. The second component is a detailed examination of one specific form of public transport. This is a three-wheeled 8-seater used in the city of Lucknow in North India. It is chosen because it is available with a petrol or compressed natural gas (CNG) spark-ignition engine (and hence could alternatively be ethanol-fuelled) and in a battery-electric version. Both parts of this data-gathering have been specific to the situation in India. In energy conversion the refinery crude composition and processes, basic resources of biomass and the mix of primary energy for electricity generation are different in each country. The types of vehicle used also vary considerably from region to region. It is observed that while CNG and electric-powered vehicles may have low and zero tailpipe emissions respectively, gross pollution from such vehicles and their associated resource systems maybe significant. In the case of electrically-propelled vehicles the gross carbon emission is comparable with that for similar petrol-engine vehicles since about 80 % of electricity production in India is fossil-fuel-based. In comparison, CNG shows a reduction of about a third. Alcohol-fuelled vehicles, by comparison, can show neutral (i.e., zero net) carbon emission. The importance of gross pollution assessments in rational choice of a fuel cannot be overemphasised.


A life-cycle or so called ‘‘well-to-wheel’’ analysis of a fuel draws attention to the fact that CO2 is produced not only in the combustion of a fuel at the point of use but also during extraction, refining and transportation of the fuel. This indirect CO2 production is generally associated with energy inputs in these processes but may also be related to the inherent nature of the processes involved (Figure1).

                Figure 1. Net energy and gross CO2 emissions

G = gross energy produced by combustion of fuel

F = total feedback energy in fuel production processes 1, 2 and 3 = F1 + F2 + F3

N = net energy available from the fuel = G – F

1. CO2 emissions

The sum total of such direct and indirect CO2 emissions may be termed gross CO2 emissions. It should be pointed out here that, apart from CO2, emission of other polluting agents from a fuel such as SOx, NOx, particulates, aldehydes and lead might also be considered. The present study is limited to CO2 emission because of its serious implications for global warming. For a transport fuel, the term ‘‘life-cycle’’ refers to althea events that begin from the source and end at the wheel. In particular it includes stages of feedstock extraction, fuel processing and refining, fuel transport, fuel storage and distribution, and finally combustion in the engine of a transport vehicle to power its wheels. As a practical example, gross CO2 emission has been evaluated for an important alternative transport fuel, bioethanol produced in Indian conditions, and this has-been compared with that for oil, compressed natural gas (CNG) and electricity. A new figure of merit for grading a fuel was proposed by the authors in earlier papers [Prakash et al., 1998; 2000] -- linking net energy and gross pollution from fuel, where bioethanol was taken as an example. Now this work has been extended and the current paper assesses the gross pollution from various transport fuels on a per kilometre basis, when actually used in similar passenger vehicles for public transport under Indian conditions.


2. Significance of bioethanol as petroleum substitute in India


India is one of the largest sugar-cane producers in the world and its sugar industry is the second largest among the Indian process industries, next only to cotton textiles [Gehlawat, 1990]. The estimated annual sugar-cane production in India [MoF, 1997] is 274 million tonnes (Mt) of which about 51 % are processed in sugar mills, 39 %is used in small gur and khandsari (raw and crude sugar) units and 10 % is used as seed material [Ravindranathand Hall, 1995]. The main by-products of the sugar industry are bagasse and molasses. Molasses accounts for about 5 % of the mass of the cane crushed and a yield of 285 litres (l) of ethanol/t of molasses can be achieved [Gehlawat, 1990]. Considering only the molasses available from sugar mills, this source can potentially produce two million m3 of ethanol a year. The annual consumption of petrol in road transport in India [TERI, 1997] is about 4.7 million m3. The calorific value of ethanol is 21.1 MJ/l compared with 31.8 MJ/l of petrol [Yacoub et al., 1998], resulting in a potential of petrol substitution by ethanol in road transport of about28 % (on equivalent energy basis) under Indian conditions From practical considerations, however, it would be easier to introduce gasohol (petrol containing 10 % anhydrous ethanol by volume) as a transport fuel, since the introduction of this blend would require no engine modifications and vehicle volumetric fuel consumption essentially remains unchanged [SEIS, 1980]. With the introduction of gasohol, the annual petrol saving potential in road transport would be approximately 0.5 million m3 at the current level of petrol consumption in India. Such a substitution should directly reduce petroleum imports and replace octane-boosting lead alkyls in petrol, as have been done successfully in many countries [Hall and House, 1995].

Blending of ethanol with petrol provides additional benefits. The changes in refinery operations that are required to produce fuel of the same octane number without lead reduce the quantity of fuel that can be produced from a barrel of crude oil. This is because reforming lower octane-rating hydrocarbon components to increase the percentage of more complex octane-boosting molecules alters the chemical constitution of the petrol. This reforming process consumes additional energy in the refining process – energy directly lost from every barrel processed. The addition of ethanol to petrol



Table 1. Process energy requirements


Energy consumption


Energy recovered











Effluent treatment



Auxiliary equipment







effectively gives the required octane boost and the reforming requirement is correspondingly reduced. This means that every barrel of petrol blended with alcohol produced decreases crude oil demand, not only by the quantity of petrol directly replaced by ethanol but also by the crude oil saved through the value of ethanol as an octane enhancer [SEIS, 1980Unleadedpetrol is now available in India but its use can create its own problems. Fuels containing high proportions of aromatics and olefins produce relatively higher concentrations of hydrocarbon compounds that have a potential to participate in reactions leading to the production of the harmful photochemical smog. In addition, some aromatic compounds are known to be carcinogenic and nerve toxins. For these reasons, the current trend favours the lowering of aromatics content in petrol [Al-Farayedhiet al., 2000].


3. Gross carbon emission from anhydrous ethanol in India.


In the case where bioethanol is to be used in India as a petrol blend in road transport without engine modifications, the use of anhydrous ethanol is essential [SEIS,1980]. Hence it is important to carry out energy and environmental analysis of anhydrous ethanol production from molasses as practised in India. With this objective, energy inputs in ethanol production were obtained from a representative industrial alcohol plant located in the state of Uttar Pradesh (UP), India. The plant, which has a production capacity of 100 m cube/day, is operated on a three-shift basis (24 h/day). The production process consists of three stages: fermentation, conventional distillation and dehydration, followed by effluent treatment that is now mandatory for all distilleries. Energy consumption in each of these stages is in the form of process steam and power derived from backpressure steam turbines. These turbines use steam generated at 4.5 MPa (gauge) from bagasse-fired boilers.Bagasse is obtained through backward integration of the distillery with a sugar mill having a cane-crushing capacity of 8000 t/day. The mill-wet bagasse contains about 50 % moisture and has a calorific value [Gehlawat, 1990] of 9.5 MJ/kg.

  Data recorded from the boiler and the back-pressure turbine used gave the following results:-

  • 1 kg of steam generation requires 0.45 kg of bagasse, i.e., 4.3 MJ of primary energy. 
  • 1 kWh of power generation requires 7 kg of steam,i.e., 30 MJ of primary energy.
  •  About 1400 m3 of spent wash produced per day from100 m3/day of distillate is treated biologically via anaerobic digestion, generating biogas. Approximately 35m3 of biogas is generated per m3 of spent wash. This biogas, containing about 60 % methane and having an approximate calorific value 23 MJ/m3, is fed directly into the boilers to save bagasse.

The energy consumption recorded during various stages of ethanol manufacture is summarized in Table 1 and more detail may be found in a previous paper by the authors[Prakash et al., 1990].


4. Carbon emissions and uptake


There are significant carbon emissions in the form of CO2 during the production process of ethanol. A large amount of CO2 is released during fermentation, as well as in the burning of biogas and bagasse in the boilers used. CO2would also be released in transporting ethanol from the distillery to the point of use and, of course, in its eventual

Combustion. In all of the above processes (except traditional transportation), however, the raw material used (molasses) and energy inputs (bagasse and biogas) are derived from biomass (sugar-cane) from the nearby fields. Therefore, one can safely assume that much of the carbon released is eventually absorbed through photosynthesis insular-cane. Hence, in this case, gross carbon emissions minus carbon uptake may be considered to be nil or, almost, very small.







5. Gross carbon emissions from oil and CNG


An accurate assessment of gross carbon emissions froma fuel requires a detailed energy analysis of its production process. However, indicative values of carbon release rates (as CO2) for fossil fuel processing and combustion are available [Goldenberg et al., 1988] and are given below:

Gross carbon emissions from natural          -             13.5 kg per GJ released in combustion      gas    


Gross carbon emissions from                         -                   19.9 kg per GJ released in combustion



Specific energy content of                              -                46 MJ/kg

natural gas [Baruah, 1993]


Specific energy content of petrol                    -                42.9 MJ/kg

[Yacoub et al., 1998]


Hence, gross carbon emissions from natural gas

= (0.0135 kg/MJ) ´ (46 MJ/kg)

= 0.62 kg C/kg of fuel

and gross carbon emissions from oil= (0.0199 kg/MJ) ´ (42.9 MJ/kg)

= 0.85 kg C/kg of fuel











Figure 2. Typical Vikram vehicles: 410P petrol-engined (left) and EV electric-powered (right)


To obtain the feedback energy requirement for CNG, en­ergy data for compression were obtained from the Gas Authority of India Ltd as follows.

  •  In a typical CNG plant, natural gas is compressed from about 40 bar to 250 bar through reciprocating com­pressors in a two-stage       process.
  • The total electricity consumption in the process (com­pressor motors, oil pumps, cooling water pumps, valves, etc.) was estimated to be in the range 0.6-0.7 kWhe/kg of natural gas.
  • The initial compression of natural gas to 40 bar from the lowest pressure of about 3 bar consumes an addi­tional 0.2 kWhe/kg of natural gas.
  • Hence, the aggregate electricity consumption in com­pression averages about 0.85 kWhe!kg of natural gas. Carbon emissions (as C02) in conventional (coal-based) electricity generation [Brown, 1992] are approximately 0.25 kg C/kWhe. About 80 % of the utility power gen­eration in India [MoF, 200 I] is thermal (mainly coal­based) and the remaining 20 % comes from carbon-free (hydro and nuclear) resources. Therefore, I kWhe power generation in India is associated with approximately 0.2 kg C emission.

Hence, gross carbon emission from I kg CNG = 0.62 + 0.85 x 0.2 = 0.79 kg C


6. Gross carbon emission from electric vehicles


    To estimate gross carbon emissions from electric vehicles, practical data was obtained from Scooters India Limited (SIL) at Lucknow (Uttar Pradesh), India. SIL is involved in the manufacture, running and maintenance of its fleet of 8-seater three-wheelers. These are called Vikram “tempos”and are used for public transport in the city (Fig­ure 2). Each vehicle uses 12 lead-acid traction batteries (6 V, 200 Ab) which run a DC series motor (72 V, 5.5 kW). The average range of the vehicle on one charge is about 100 km and the data recorded from the charging station shows electricity consumption in the range 16-18 kWhe for fully charging a discharged battery bank. Since I k Whe power generation in India is associated with ap­proximately 0.2 kg C emission (as in the above para­graph), gross carbon emission from SIL's electric vehicles is estimated as:

[(0.2 kg C/kWhe) x (17 kWhe)]/ [(l00 km) x (8 passen­gers)] = 4.3 g C/passenger-km


7. Comparative assessment of gross carbon emissions from various transport fuels


    Apart from manufacturing electric vehicles, SIL is also involved in the manufacture of petrol- and CNG-driven 8-seater three-wheelers for public transport. These are also known as Vikram tempos as they are similar to the electric vehicles in design, but have an engine of 3.4 kW (200 cm3, 2-stroke) and steel chassis, unlike the fibre-re­inforced plastics used for electric vehicles. There is also a diesel vehicle but this is smaller and not directly com­parable so has been omitted from this study. Fuel con­sumption in the petrol and CNG-driven tempos was observed as follows.

I kg CNG is required for 35 km average run or I I petrol for an average run of 18 km. Considering gross carbon emission from petrol and CNG per kg of fuel, gross carbon emission from SIL' s tempos is evaluated as: 4.4 gC/passenger-km for petrol-driven vehicles and

2.8 gC/passenger-km for CNG-driven vehicles.

A comparison of the gross carbon emissions from various transport fuels in Indian conditions is shown in Table 2.

8. Conclusions

It is concluded that bioethanol, as produced in India, can play a significant role in reducing life-cycle carbon emis­sions. If used as a petrol blend, it can help reduce oil imports as well as reduce aromatics pollution from un­leaded petrol.


                        Table 2. Gross carbon emissions from various transport fuels



Indicative values of gross carbon emissions from various alternative transport fuels have been evaluated and are presented in Table 2. The table shows that gross carbon emissions from electric vehicles are significant and are comparable with those from oil-fuelled vehi­cles, while CNG is the least polluting among conven­tional fuels. This shows that although some fuels may be "clean" locally, they can cause considerable pollu­tion on a global basis. The study further demonstrates that gross pollution from a fuel would decrease if clean and renewable energy resources were used in its pro­duction process, as in the case of bioethanol manufac­ture in India.

The study needs to be extended, of course, to assess gross emissions of other pollutants from a fuel, e.g., SOx, NOx, particulates, aldehydes and lead, to obtain a com­prehensive gradation of fuels, thereby helping in the ra­tional choice of a fuel.

A comparison with similar life-cycle assessments for automobile fuel/propulsion system technologies for North America is provided below which further cor­roborates the conclusions drawn above.

Comparison with similar life-cycle assessments for automobile fuel/propulsion system technologies


   Comparing fuels and propulsion systems requires a comprehensive, quantitative, life-cycle approach to the analysis. It must be more encompassing than “well-to-­wheels” analysis. Well-to-wheels comprises two compo­nents, the "well-to-tank" (all activities involved in producing the fuel) and "tank-to-wheel" (the opera­tion/driving of the vehicle). The analyses must include the extraction of all raw materials, fuel production, infrastruc­ture requirements, component manufacture, vehicle manu­facture, use, and end-of-life phases (dismantling, shredding, disposal/recycling) of the vehicle. Focusing on a portion of the system can be misleading. The analysis must be quantitative and include the array of environ­mental discharges, as well as life-cycle cost information, since each fuel and propulsion system has its comparative advantages. Comparing systems requires knowing how much better each alternative is with respect to some di­mensions and how much worse it is with respect to others. Since focusing on a single stage or attribute of a system can be misleading, e.g., only tail pipe emissions, the life­cycle implications of each fuel and propulsion technology need to be explored.

MacLean and Lave [2003] have provided a very de­tailed review of a dozen studies on the life-cycle impli­cations of a wide range of fuels and propulsion systems that could power light-duty vehicles in the US and Canada over the next two to three decades. The studies vary in the fuel/propulsion options they consider, the environ­mental burdens they report and the assumptions they em­ploy, making it difficult to compare results. All of the studies, however, include the "well-to-tank" and "tank-to-­wheel" activities and the majority of the studies include a measure of efficiency and greenhouse gas emissions as­sociated with these activities. Comparison has been lim­ited to these activities and measures.

Table Al provides a summary of the ranges of effi­ciency and greenhouse gas emissions reported in the stud­ies for the well-to-tank portion for the various options. For the well-to-tank portion for the production of elec­tricity, renewable fuels and hydrogen, differing fuel pro­duction pathways are most important. Owing to the range of different production options for these fuels (as well as other issues such as study assumptions), results are much more variable. In addition, there is less experience with producing these fuels, resulting in more uncertainty. It is important to distinguish between total and fossil energy required for production when comparing efficiencies among the fuels. Petroleum-based fuels have the highest efficiency for the well-to-tank portion when total energy is considered. However, if only fossil energy is consid­ered, biomass-based fuels such as ethanol become more attractive.

The tank-to-wheel portions are more difficult to com­pare. Each study uses its selected vehicle (e.g., conven­tional sedans, light-weight sedans, pick-up trucks) and many present assumptions regarding the vehicle efficien­cies. The studies, however, do not generally report the range of assumptions or test conditions.


Table A1. Comparison of life-cycle inventory studies: well-to-tank

efficiencies and greenhouse gas emissions


1. Efficiency (%) is defined as: (energy in the fuel delivered to consumers/energy inputs

to produce and deliver the fuel) 100, e.g., 100 MJ of energy input results in 80-87

MJ of petrol delivered to the consumer.

2. Negative GHG emission values for ethanol result from carbon sequestration during

feedstock growth as well as if a credit is given for selling excess electricity (produced

through cogeneration schemes) to the grid and therefore offsetting CO2 emissions from

conventional electricity generation.



The well-to-wheel results (the sum of the well-to-tank and tank-to-wheel activities) of the studies are still more difficult to compare. The baseline vehicle (with a few ex­ceptions) is a current petrol-fuelled ICE port fuel injection vehicle; it combines an efficient well-to-tank portion with a relatively inefficient tank-to-wheel portion. A direct in­jection diesel vehicle is considerably more efficient and therefore results in lower emissions of carbon dioxide even though the carbon content in the diesel (and hence the well-to-tank portion of the C02 emissions) is higher than that in petrol. Fuel-cell vehicles have a high theo­retical efficiency but generally a low-efficiency well-to-­tank portion, which offsets some of the vehicle efficiency benefits.

Table A2 shows the ranges of values reported in the life-cycle studies for the well-to-wheel greenhouse gas emissions. All of the fossil fuel options result in emissions of large amounts of greenhouse gases. Ethanol and hy­drogen have the potential to reduce greenhouse gas emis­sions significantly. This, however, is highly dependent on the pathways for ethanol and hydrogen production, espe­cially the amount of fossil fuel inputs during production. Some of the hydrogen options result in higher greenhouse gas emissions than those of a petrol ICE vehicle. Results for hybrid electric vehicles (HEVs) are dependent on the efficiency improvements over conventional vehicles that are assumed.A numerical comparison of C02 emission data pre­sented in Table A2 with those reported in Table 2 should be made with caution. The large differences in numerical values arise from the differing manner in which C02 emissions have been expressed. In Table 2, emissions are expressed in grams of carbon (only) released as CO2 per passenger-km travelled. In Table A2, emissions are in grams of C02 equivalent per km travel of the vehicle ex­amined. C02 equivalent refers to the amount of carbon dioxide by weight emitted into the atmosphere that would produce the same radiative forcing as a given weight of an­other greenhouse gas, e.g., methane or oxides of nitrogen.

Carbon dioxide equivalents are the product of the weight of gas being considered and its global warming potential.

Table A2. Comparison of life-cycle inventory studies: well-to-wheel

greenhouse gas emissions




Numerical differences not withstanding, broad conclusions drawn by MacLean and Lave are very similar to what has been obtained under Indian conditions in this article: all of the fossil-fuelled vehicles (including electricity-driven) result in large GHG emissions. The two options that have potential for the largest GHG emission reductions are the ethanol and the hydrogen-fuelled vehicles if the fuels are produced with little or no fossil fuel inputs.



What is CNG? Properties of Natural Gas:

CNG is the short form of Compressed Natural Gas. The Natural Gas has less energy density as compared to Liquid Fuel and hence it is compressed to over 200 Kg/cm² (g) pressure to make it CNG for use in the automobile sector. In its natural form it is colourless, odourless, non-toxic and non-carcinogenic. However, this natural gas is mixed with an odorant to add flavour similar to the odour of LPG from a domestic cylinder so as

to facilitate detection of its leakage. The typical composition and physical properties of CNG (i.e. Compressed Natural Gas) is as follows:

Typical Composition:

Methane : 88%

Ethane    : 5%

Propane  : 1%

CO2       : 5%

Others    : 1%


Total      : 100%


Physical Properties:

Non-toxic – Natural gas being lead/sulphur free, its use substantially reduces harmful engine emissions. When natural gas burns completely, it gives out carbon dioxide and

water vapour - the very components we give out while breathing!

Lighter than air – Natural gas being lighter than air, will rise aboveground level and disperse in the atmosphere, in the case of a leakage.

Colourless – Natural Gas is available in the gaseous state, and is colourless.

Odourless – The gas in its natural form is odourless, however, ethylmercaptan is later added as odorant so as to detect its leakage.

Compressed Natural Gas (CNG) is used as a fuel in transport sector in many countries. It is a safe, clean burning and environment friendly fuel. It has been established that exhaust emissions like hydrocarbons and carbon monoxide are significantly reduced as compared to other fuels. Toxic emissions such as lead and sulphur are completely eliminated. Existing petrol vehicles can use CNG by fitting a conversion kit. The CNG converted vehicles have the flexibility of operating either on petrol or on CNG.

An experimental programme to use CNG as fuel in transport sector in the country was initiated by GAIL in 1992, whereby CNG was made available in Delhi, Mumbai and Baroda. The supply of CNG in Mumbai and Delhi are managed by two joint ventures viz. Mahanagar Gas Nigam Ltd. and Indraprastha Gas Limited respectively and in Surat and Ankleshwar, by a private company. The average cost of converting a petrol car to CNG is about Rs.35,000. There are over 10,000 CNG converted Petrol vehicles in Mumbai and over 3000 such vehicles in Delhi. 11 buses of DTC are running on CNG in Delhi, with 2 existing diesel buses converted to CNG on trial basis.

CNG dispensing retail outlets on mother-daughter concept as well as online dispensing units have been set up in Delhi. Under the former system, Natural Gas is compressed and filled into truck mounted cascades (basket of cylinders) in the mother compressor station and transported to daughter units for dispensing to CNG vehicle. The mother station initially set up in Ghaziabad has been re-located and brought near to Delhi at Sarai Kale Khan, in May’97. At present there are seven daughter and four on-line dispensing retail outlets in Delhi. Further expansion of the infrastructural network to 80 CNG outlets is proposed by March 2000. The process of acquiring land sites to set up the required number of outlets is going on.




   Reasons for switching over to this alternate fuel are mainly:


1. Economic benefit: The cost of CNG is almost a third of the cost of Petrol in terms of calorific value resulting in substantial saving in fuel cost, and investment on the CNG kit is paid back in a short period

2. Environment friendly: The use of CNG as a fuel reduces vehicular exhaust emissions significantly. Carbon Monoxide emissions are reduced by 70 to 90% and Hydrocarbon emissions by 40 to 60% as compared to vehicles that use the conventional fuel - Petrol. Carbon Dioxide emissions, a cause for global warming, are also reduced significantly by 10%

3. 100% Income Tax Depreciation: Corporate Organisations, firms, etc. can claim 100% depreciation on a CNG Conversion Kit as this is a pollution controlling equipment. Organisations that buy CNG Conversion Kits should consult their Income Tax Consultants and avail of the depreciation benefits

4. Flexibility and ease of use: The basic engine characteristics of a vehicle are retained while converting it to run on CNG. The vehicle therefore is capable of running either on Petrol or CNG at the flick of a switch on its dashboard.



The Fuelling Process

There are very few CNG refuelling stations. Of the ones that exist, there are three basic types. Fast fuelling stations which take five to ten minutes for refuelling, ideal for retail roadside pumps. Slow fuelling stations which take from five to eight hours to fill, ideal for a fleet of vehicles which have a long idling time. Combined Fast and Slow fuelling stations which can cater to both the above categories.CNG is stored at compression stations which are directly connected with the gas pipeline. Here the gas is compressed to a required pressure and aids fuelling. CNG can also be transported to other retail outlets by cylinder trucks. these trucks carry a number of cylinders which provide CNG to fuel stations which are not connected by pipelines. These fuelling stations could be placed alongside petrol and diesel pumps too. the whole process requires proper infrastructure and transportation.

Bi-fuel Possibility

Vehicles can also be operated in the dual mode like Petrol-CNG and Diesel-CNG. Experiments of these kinds have been conducted on vehicles by TELCO,Kirloskar Cummins Ltd., Ashok Leyland, IBP, OIL, Delhi transport Corporation and Gujarat  Road Transport Corporation. The results were quite satisfactory.

The Gas Authority of India Limited (GAIL) has requested vehicle manufacturers to nominate workshops and undertake conversions on their vehicles. The actual performance could be monitored by the Indian Institute for Petroleum (IIP), Kit suppliers from Italy and New Zealand have joined hands with oil marketing companies and vehicle manufacturers to train and initiate conversion from petroleum products to CNG.

Many countries around the world, including India, have abundant reserves of natural gas. Hopefully, it is only a matter of time when things begin to take a turn for the better and CNG would be as prevalent as petroleum products.

What does the kit comprise of ?

  1. The Cylinder

The cylinder is used to store CNG at a working pressure of 200 bar. It is fitted with a shut-off valve and a safety burst disc. The cylinders are type approved by the Chief Controller of Explosives, Government of India.


  1. The Vapour Bag.

Fitted onto the cylinder, the Vapour Bag is used to enclose the cylinder valve and the pipes connecting it and is vented out of the car


  1. The High Pressure Pipe

This High Pressure Pipe connects the refuelling valve to the CNG Cylinder and Pressure Regulator


  1. The Refuelling Valve

The Refuelling Valve is used to refuel the CNG cylinder


  1. The Pressure Regulator

The Pressure Regulator has a Solenoid Valve to shut-off gas supply to the engine. The CNG stored at a high pressure in the cylinder is reduced to just below atmospheric pressure by this unit. This negative pressure is also a safety feature that will not allow gas to pass through when the engine is not running.


  1. The Gas-Air Mixer

The Gas-Air Mixer is a unique component, specially designed to suit each engine model. It precisely meters gas fed into the engine.


  1. The Petrol-Solenoid Valve

The Petrol-Solenoid Valve is used to cut off petrol supply to the engine when it is run on CNG


  1. The Selector Switch

The Selector Switch is fitted at the dashboard, enabling the driver to choose either the CNG mode or the petrol mode of operation. The electronics built into this unit also ensures safety by switching off the gas solenoid whenever the engine is switched off. It also serves as a fuel indicator for the quantity of CNG available in the cylinder




The use of CNG in vehicles has lead to considerable reduction in air pollution as is evident from the following data:


  1. Auto rickshaw – Three wheelers:






B. Passenger Cars:



C. Diesel Buses:




Pilot project of GAIL :

  • Objective: A pilot project was initiated by GAIL (India) Ltd. in collaboration with Indian Institute of Petroleum, Dehradun to establish the feasibility of using CNG as an alternative to liquid fuels such as Diesel & Petrol used by buses & automobiles in 3 cities namely Delhi, Mumbai & Baroda.


  • Infrastructure of GAIL under pilot project: 1 Mother station was initially put up at Ghaziabad which has since been shifted to Seakale Khan. This mother station was feeding to 5 daughter stations in Delhi. 3 Nos. online stations were added making total 9 Nos. of Cogitations during the pilot phase of the project. The station design and safety norms followed were as per New Zealand standards.




CNG is totally safe. It is non-toxic, non-corrosive and non-carcinogenic (totally free from cancer – inducing agent). CNG being predominately methane (CH4) is 0.6 times lighter then air while petrol is 3-4 times heavier. Being lighter then air, it disperses fast unlike petrol or LPG, which tends to remain around the place of leakage. CNG does not catch fire easily, as it requires a much higher concentration of 5.15% in the air to ignite against the 1.8 % required for petrol. CNG also requires a higher ignition temperature of 540O C as compared to with petrol, which requires 232-282 O C, which prevent CNG from catching fire as quickly as petrol. CNG cylinders are very robust materials, which minimizes the chances of leakage. CNG promises a breath of fresh air and is environmental friendly. CNG is lead-free and substantially reduce the harmful engine emission to keep the surroundings and air clean.


A special report of Environmental Pollution and Control Authority (EPCA) Committee headed by Sh. Bhurey Lal comprises of Secy. Transport, Delhi Government, A member from Center for Science and Technology and a member each from Ministry of Environment and Ministry of Petroleum suggested use of CNG in all commercial vehicles in NCR in addition to ban on registration of diesel cars in Delhi. However, the Delhi Government was in favour of propane gas as alternative fuel and set up a propane gas station for DTC buses but the Center did not approve the propane conversion kit. Even the option was not favoured by Sh. Bhurey Lal Committee. Thus the Hon’ble Supreme Court accepted CNG as alternative fuel for Gasoline and diesel vehicles.


The Hon’ble Supreme Court vide its orders on 28.7.1998 fixed the dead line of 31.3.2001 for gasoline/diesel run commercial vehicles in view of the June 1998 affidavit of Secretary Transport Delhi Government assuring that the City Bus fleet could be converted to CNG mode by 31.3.2001. 


CNG has been successfully used as auto fuel in several countries. As of now, there are more than 12 lakh CNG driven vehicles in the world. Argentina, Canada, Italy, New Zealand and USA are among the countries where CNG is being used as auto fuel for some years/. Pakistan is also successfully running a staggering 1, 60,000 vehicles on CNG. Almost entire transport system is running on CNG in Pakistan. This conversion process has been on the past five to six years. Most vehicles in Japan run on LPG, but , now they are also opting for CNG. Even Bangladesh is also in its way to convert its transport fleet to CNG mode. In India, Mumbai has been the first to use the CNG mainly for taxies.

VEHICULAR AIR POLLUTION IN DHAKA: The air pollution in few big cities of Bangladesh is a very serious concern. As per a World Bank Study, as many as 15000 deaths (5000 in Dhaka), a million cases of sickness requiring medical treatment and 850 million cases of minor illness can be avoided annually if air pollution levels in the country’s four principal cities are reduced to match standards in force in developed countries. The same report further estimates the economic cost of these avoidable deaths and sickness to be US $ 200 to 800 million every year. Dhaka has heterogeneous traffic flows. Three wheelers, out of which ninety percent are two stroke engines baby taxis and two wheelers, are dominant in the vehicle fleet in terms of both number and mileage. The number of two stroke engine three wheelers has tripled from 1990-96. Air pollution levels in Dhaka are considerably higher than the Bangladesh standards or the World Health Organization (WHO) guidelines for residential areas. Most experts here blame three-wheelers with two-stroke engines and the heavy-duty diesel vehicles for the high pollution levels. They see leaded gasoline as the principal source of lead in the atmosphere.  As many countries have phased out leaded gasoline, Bangladesh is also working on the problem. Due to pressure from green lobby to reduce air pollution in Dhaka, the government decided that three-wheelers would be made to run on non-polluting compressed natural gas (CNG). Initially, all such decisions remained on paper. The reason might be that there was support for converting three-wheelers to CNG instead of banning them so as to prevent the sudden unemployment of at least 250,000 people. Here it is worth mentioning that motor vehicles per thousand people in Dhaka city is still low in comparison to other capital cities of developing countries but the likely higher economic growth in the future with even faster increase in population will definitely result in fast growth in vehicles fleet in Dhaka. Besides the composition and size of vehicle fleet, poor maintenance, excessive commercial use, fuel adulteration, use of lubricants of sub standard quality and poor management of traffic will further result in severe congestion and vehicular pollution in Dhaka. 

Keeping in view the above problems, Dhaka Urban Transport project was launched by the Government of Bangladesh and the Dhaka City Corporation. The International Development Association (IDA), the World Bank’s concessionary arm approved the credit of US $ 177 million for the project. The Government also wanted to develop an Air Quality Management System to reduce Dhaka’s severe air pollution. The World Bank provided Bangladesh a $ 4.7 million Learning and Innovative Loan in 2000 for a Bangladesh Air Quality Management Project (AQMP) under which Dhaka would pilot new ways of controlling urban air pollution.

 Next step in the direction of reducing air pollution in Dhaka is to popularize the use of CNG vehicles, as in many other cities of the world.

ECONOMICS OF CNG VEHICLE PROGRAM IN DHAKA: Worldwide, improving air quality in urban settings has been a long-standing planning objective and road transport using diesel vehicles has been identified as major contributor to such air pollution. To help address this problem, increasingly stringent vehicle emission standards came in to force worldwide. It also stimulated research into alternative fuels and technologies that promise cleaner and lower emissions. Various fuels that are alternatives to diesel and petrol have been proposed for use in vehicles. Alternative fuel vehicles use such fuels as compressed natural gas (CNG), liquefied natural gas (LNG), methanol, ethanol, bio-diesel fuel and propane. Among these fuels, Natural Gas, either in the form of CNG or LNG, is more in the news. Reasons behind the popularity of these fuels are economic as well as environmental. Many countries like Argentina, Canada, Italy, New Zealand and United States of America have substantial NGV programs. Brazil, Chile, China, Colombia, Egypt, India, Indonesia, Mexico, Pakistan and Thailand are in various phases of developing such programs.As early as in 1985-86, Bangladesh Petroleum Corporation started a project to use CNG in vehicles instead of Gasoline. The World Bank donated Tk 225.1 million to initiate the project. The primary objective of this project was to reduce vehicular emissions as combustion of CNG produces less pollutant than the gasoline.After a decade in 1996, there were only 86 vehicles converted under the project, while in that year the volume of traffic in Dhaka only was composed of 84411 cars, 9135 buses, 15600 trucks, 66360 three wheelers and 121156 two wheelers. In year 2002, there were only five CNG filling stations in Dhaka, out of which 4 has been established by Rupantarit Prakritika Gas Company Limited (RPGCL) and one was in joint venture between a Chinese company and RPGCL. The gas supply to these filling stations was quite erratic, particularly during morning hours when gas pressure decrease due to domestic use. The need was felt to create an efficient transmission and distribution network to improve and secure a reliable supply of gas. Further, as conversion of vehicles to CNG has now become imperative to save the city from the menace of air pollution that has turned the capital into almost a 'gas chamber', need was felt to set up number of CNG filling stations to cater the growing demand when large numbers of vehicles get converted to CNG. Realizing the urgency the Bangladesh Government has taken up the CNG conversion process issue within its 100-day action plan for implementation. To expedite the process, the government has already given permission to 13 private companies to set up CNG conversion units. The economic benefits arising from the CNG vehicle program in Dhaka are expected to accrue to consumers of various categories such as vehicle owners, users of transport, workers and the economy in general.  Additionally, benefits on account of improved environment and thus health status of the population in Dhaka and macro economic contribution of the CNG program for further development of the energy and particularly, gas sector are equally important.

 Economic Benefits to Vehicle Owners & Users:The amount of consumer surplus (economic benefits) arising from CNG Program will directly benefit the vehicle owners. Operating cost of CNG vehicles is lower than that of vehicles run on alternate fuel i.e. petrol or diesel. Thus vehicle owners will benefits from reduced operation costs in terms of resource cost savings. For instance, if hundred percent of the bus fleet of the Dhaka is converted to CNG, the present value of likely stream of economic benefits in terms of resource cost savings in the coming twenty years period, at twelve percent rate of discount, will be about 16000 million Taka. Similarly, the conversion of whole vehicle fleet of Dhaka to CNG will fetch the present value of likely stream of economic benefits in terms of resource cost savings over a twenty year period, at twelve percent rate of discount, to the tune of 32000 million taka.

 However, the experience shows that vehicle owners will not transfer a portion of consumer surplus to end-users. Therefore, intervention by Government / administration is required to ensure that end users of transport also get a share in consumer surplus arising from transport component in the proposed project.

 Benefits to Operators of Filling Stations:Another potential beneficiary of the CNG program will be the CNG filling station operators because the demand for CNG as fuel is going to increase and they will earn from the increased sale of CNG. Initially, the profit might not have been significant because of low gas pressure leading to sub optimal sale proceeds at the end of the day. However, their income will significantly increase due to the program that will ensure the regular supply of gas with optimum pressure

 Network Benefits: Total consumption of gas by vehicle fleet of Dhaka will be less than the supply of gas provided by an optimum size of the transmission and distribution network. Therefore, consumers of other categories such as households, commercial or industrial consumers will consume the additional supply of gas, over and above the consumption by transport in the city. Discussions (by author a year back) with RPGCL, the distributor of gas in Dhaka, revealed that presently, the supply of gas is less than demand, particularly during peak hours. It results in lower than optimum supply pressure in the existing gas distribution network and thus existing consumers did not get the proper supply of gas. As suggested by officials of RPGCL, the investment in up gradation and augmentation of gas transmission and distribution network will help in improving the supply of gas to existing consumers by maintaining optimum supply pressure in the network. The possible consumers of the additional supply of gas by the upgraded network may be grouped under to heads depending upon the physical location of the newly added transmission and distribution network and its area of coverage. First group will be households and commercial consumers in the Dhaka city and other possible consumers may be industries in the outer periphery of Dhaka. In case of first group of consumers, i.e. household and commercial, economic benefits on account of improved network for supply of gas will be in terms of resource cost savings because the cost of natural gas is lower than that of other alternate fuels. In other words, consumers will be able to get same amount of energy, which they used to get from alternate fuels, by spending less. Such benefits will occur to existing as well as new consumers.In case of use of gas in industry, the economic benefits will be in terms of net incremental output (net value added) to the economy. The quantum of such benefits depends upon the type of industries likely to consume the additional supply of gas. Discussions with officials of RPGCL indicated that a few gas based power plants have been proposed in Dhaka region, which may be the likely consumers of the additional gas supply. This possibility becomes even more likely in the light of the fact that the gas based power plants in Bangladesh are not getting the requisite supply of gas for power generation. However, possibility of supplying gas to industries in outer Dhaka region simultaneously with the supply to CNG filling stations may not be feasible because of the incompatible spatial patterns of industrial development and spread of city. Therefore, the network benefits are more likely to occur to household and commercial consumers.

 Health Benefits due to Reduced Pollution : Proportionate share of Dhaka in reported cases of death and sickness was taken on the basis of proportionate share of Dhaka in the total population of major cities of the country and thus, economic benefits associated with reduced health problems due to use of CNG was estimated for the city. The benefits in terms of savings in cost of health impact due to air pollution was estimated under three heads, viz. loss of human capital – deaths due to air pollution, loss of work person days on account of sickness due to air pollution and expenditure on treatment.

The estimated cost of health problem due to air pollution in Dhaka comes to about Tk 25000 million per year. In other words, Tk 25000 million as health benefits can occur to the economy, if an air pollution level in Dhaka is reduced to match standards in force in developed countries.

 Macro Economic Benefits -Foreign Exchange Savings: It is generally argued that market for gas in Bangladesh is limited This argument seems misplaced when demand scenario for gas in Bangladesh is analyzed in the context of possibilities of replacement of other imported fuels such as petrol and diesel by gas. Judging from the size of the oil bills in the BOP, the fact of the matter appears to be that Bangladesh had been an energy deficient country.Projections[ by Power System Master Plan (PSMP) put the likely growth in energy demand in Bangladesh at 10% per annum. Assuming the same rate of growth in demand for petrol and diesel, calculations reveal that demand for these energy products is going to be more than four times after 15 years.






Projected* Demand for Petrol and Diesel in Bangladesh

‘000 MT































 Projections are based on power demand forecasts made by the Power System Master Plan (PSMP), which predict that power demand is going to grow at 10% per annum in the country.

Keeping in view the current import bill of the country for these fuels, limited available reserves of petroleum and exploration activities there, the domestic production is not going to meet this increasing demand. To meet the increasing demand for petrol and diesel there are two options available with the government- either increase the imports or replace the use of these fuels by domestically produced natural gas.

 The first option has no economic logic. For example, in 1995-96, 1007 thousand MT of diesel was imported which was valued at 183 Million US$. Assuming that the ratio between imported fuels and domestic production will remain the same, as at present, and demand growth will be as predicted by PSMP, the likely quantum of import of diesel alone will be about 6700 thousand MT in 2015.






 Projected Imports of Diesel in Bangladesh














 Thus, considering the existing level of imports of these products and precarious position of foreign exchange reserves, Bangladesh cannot afford to depend on imports of energy fuels to meet the increasing demand.The other viable option is to replace the petrol and diesel by natural gas as a fuel in industry and transport.For example, let us consider the case of replacing use of imported diesel by domestically produced natural gas in the industry and transport sector, and resulting foreign exchange savings. Since the replacement of diesel with gas is a gradual process and takes few years to fully materialize, the savings in foreign exchange will be smaller in the initial years. But after 4-5 years such savings will pick up.  Thus the import substitution may save the country foreign exchange to the tune of about US$ 90 Million in 2005, which may increase to about US$ 330 Million in 2010.  

Other Prospects: Presently, the industry contributes only about 18% of GDP in Bangladesh. But the analysis of historical changes in structure and composition of GDP in industrialized and newly industrialized countries indicate that the relative share of industry, transport and services sector in the GDP increases with the increase in per capita GDP and industrialization. With such structural changes in the economy of Bangladesh, the per capita consumption of energy will also increase and, in this context, the role of gas sector as a strategic sector to pick up the economic growth is very crucial. As the demand for energy increases in the economy the gas sector will develop further and cater to the demand either by increasing supply in its present pattern of usage and or through import substitution. The CNG vehicle program in Dhaka will play the role of catalyst to speed up the process of development in the gas sector.  Here, it is timely to comment that the need is to link energy sector growth strategy with trade, business, industry and agriculture growth strategy in the mid to long term.  Besides, further development of gas sector will help Bangladesh to export gas to earn foreign exchange. Although the decision to export gas is a political one, but possibilities of export are intrinsically related with the development of domestic market for gas. Activities related with development of domestic gas market such as CNG program in Dhaka give impetus to gas exploration and infrastructure development activities, and thus set the stage for export of gas. Ultimately, it will help in picking up the industrialization and economic growth through forward and backward linkages and thus further expansion of the domestic and international market for gas.

Getting into the CNG mode



Petrol/diesel vehicles can be made into CNG mode by:

1) Replacement of petroleum vehicles into new CNG vehicles Retro fitment with new   CNG engines

2) Conversion of petrol/diesel vehicles to CNG mode






Conversion technology was developed by the Indian Institute of Petroleum, Dehradun (U.P). The technology was reported to be quicker and extremely cost effective. Delhi Government approved this scheme of conversion of petroleum vehicles into CNG mode on 20.10.1999. The Hon’ble Supreme Court on 16.2.2001 ordered that only those CNG buses to ply on Delhi Roads which are certified by the Retro fitting companies authorized by any of the following testing authorities:

Automobile Research Association of India, Pune (Maharashtra).

Vehicle Research & Development Establishment, Ahmednagar (VRDE).

Indian Institute of Petroleum, Dehradun (U.P).

On the basis of approved conversion technology, the conversion of diesel bus to CNG mode is first major technology achievement of India in the World.

Transporters/Operators have been cautioned to get it install the CNG kits at a workshop authorized by its suppliers or Manufacturer.



Government envisaged the body fabrication problems. No single fabricator was able to supply the bus bodies as required in view of the limited time. Hence the body fabrications work was allotted to distant body fabricators at Mumbai, Jamshed Pur and Ahmedabad in addition to in and around Delhi. Couple of months was wasted in getting the Railway to ferry the CNG chassis to distant body fabricators. Later on the chassis were transported through pullers, which costed an increase of Rs. 1 lakh per bus body fabrication because Indraprastha Gas Limited shown its inability to provide mobile cascade enroute for filling CNG chassis.




The authorized manufacturers built up about 2200 new CNG buses, which started plying on Delhi Roads by using an obsolete ignition system, which resulted a incident of fire causing injuries to five persons on 5.8.2001.

These buses have a distributor based ignition system, which can be dangerous if the CNG cylinders are leaking. The distributor produces sparks, which ignites the CNG gas inside the ignition chamber. In addition, distributors also produce sparks outside the chamber. This makes them vulnerable to the highly inflammable CNG. It is a first generation system, which has been discarded in many countries. It is not known that why our manufacturers in India are using the dangerous technology. China has been the latest to ban this obsolete technology. These new CNG buses with distributor based ignition system are moving bombs on our roads. They need immediate replacement.

No doubt CNG is a safe fuel, but if it is exposed to sparks, it bounds to catch fire. The safest option is third generation distributor – less ignition kits. It produces sparks inside the ignition chamber and not outside. It is entirely controlled by computer driven system. It is learnt that this technology is being adopted by our conversion companies.




Safety norms for CNG run vehicles have not been notified till now. It is learnt that the draft safety norms drawn by Bureau of Indian Standards are under process of approval and are likely to be finalized and approved by the end of this year i.e. 2001. There are no comprehensive legally enforceable rules to govern the safety of CNG vehicles plying on Delhi roads and interim draft prepared by the Pune based Automobile Research Association of India is only document which lays down the safety standards. Safety norms should be specified in the Central Motor Vehicles Rules. In the absence of Law, many violators can go scot-free.

CNG run vehicles norms are in the nascent stage globally as well. The norms evolved by the International Organization of Standards (ISO)- the Apex body under the United States Umbrella are also in the final draft stage.

Safety and maintenance go hand by hand, when one talk about CNG with Delhi’s entire commercial vehicles fleet being converted to the CNG mode, safety concerns need to be addressed on priority. Norma applicable to diesel buses are being adopted for CNG buses.



The requirements for the components of CNG run system have been drawn considering the draft norms of BIS, which are briefly discussed as under:



Design requirements for CNG run systems are:

  1. Withstand changes in environmental temperature and other echo conditions safety during operational life.
  2. Be located with full regard for anticipated damage. Such damage may be caused by input from the vehicle or by extraneous input such as heat, road debris, automotive chemical splash (brakes liquid, oil, and petrol, cooling liquid, by rust and so forth.
  3. Be fitted so that they are not the outer most, highest or lowest parts of the vehicle.
  4. Be fitted so as not effect ground clearance, approach angle, ramp angle and departure angle.
  5. Be located so that they will not suffer corrosion by accumulation of water and cargo chemicals.



  1. It shall be provided with a cap to prevent the entry of dust and foreign metal.
  2. The fuel type, expiry date of the gas cylinder and the service pressure for the vehicles written in permanent ink should be displayed near the receptacle.



General requirements :

  1. Gas cylinder shall be provided with the cylinder valve and pressure relief devices.
  2. To prevent heat damage, they should either use a heat shield or be located with respect to the exhaust system, so that their side temperature shall not exceed the value specified by the vehicle and the cylinder manufacturer.
  3. All gas cylinders shall be protected from ultra violet radiation.
  4. The gas cylinder shall be securely attached to the vehicle to prevent it from slipping, rotating and dislodging.



CNG cylinders are made from seam less tubes of alloy steel skin to oxygen cylinder This ensures there are no joints and the walls of the cylinders is made of very robust material. This also prevents leakage.



The density of material (alloy steel) is around 7.86 gms per cubic centimeter. Original cylinder weighs between 52 to 64 kg. Depending on the capacity of cylinder. With 50 litres. Capacity has a 316 mm dia and is 850 mm length, while those with 65 liters capacity have a 316 mm dia and 1060 mm long.



CNG cylinders are tested to resist pressure up to 350 bar as against the working pressure of 200 bar. The cylinders are put through severe abused tests before being approved by the Statutory authorities



CNG storage cylinders fitted in the vehicle should bear the name of the manufacturer, BIS specifications, IS- 7285, Date of manufacture and testification, capacity, batch number, serial number etc.



Spurious cylinders are not approved specified cylinders. They do not conform I.S. –7285. They bears welding mark on their body. They are made of separate sheets. They are neither manufactured by the authorized manufacturer nor testified.



All CNG cylinders are certified by the Nagpur based Chief Controller of explosives under IS 7285 BIS before installation.


There are three approved manufacturers for CNG cylinders as per specification.

  1. M/s Everest Kanto Cylinder Ltd., Tarapur.
  2. M/S Bharat Pumps & pressures India Ltd., Naini (Allahabad).
  3. M/S Maruti Koatsu Cylinders Ltd.. Halal (Gujrat)


In addition to above, CNG cylinders of the following foreign Companies conforming to NZS-5454 –1989 read with IS-7285 have been also approved by the Chief Controller of Explosives, Nagpur.


  1. M/S Fiber Industries, S.p.A. Italy
  2. M/S Argentile, S.A., Argentina.
  3. M/S Worthington Cylinders, G nb H, Australia.
  4. M/S UEF Chester field Cylinders, England



The approximate cost of 65 ltrs. genuine cylinders varies from Rs. 10000-Rs. 15000, whereas, it is Rs. 5000/- or so for spurious cylinders.



SAFETY VALVE (Pressure relief device):

It shall be protected from dirt and water ingress and far from sources of ignition and heat in the vehicle when the rubber component in the safety valve is substandard or not fitted properly, leaks are bound to occur. Metal to metal interfaces can not be made leak proof unless there is a rubber component (Gasket) in between. Further gasket and valves used in CNG vehicles should be of standard quality and bear ISI/BIS specifications.



Components located down stream pressure regulator shall be protected from pressurization due to regulation failure.



Pipe work shall be laid if possible on the chassis in such a way that no damage from intrinsic vibration occurs (resonance with engine vibration) and there are no friction points.




The vehicles CNG fueling system shall be tested for leakage. The cylinder and parts of the gas system shall be in such a system so that any leaking or venting gas from the fueling system does not enter the driver and the passenger compartment, boot or other spaces, which are not sufficiently ventilated. Any gas shall be directed safely to the atmosphere.



  1. The ignition sources shall be minimized to prevent fire in a vehicle.
  2. Electric/Electronic components in gas light housing shall be suitable.
  3. The location of electric cables and mountings shall be design to protect against ignition of potential leaking gas.



There are two types of nozzles: -

  1. New Zea Land standard (NZS)- The smaller ones (which comes fitted with the kit).
  2. Natural gas vehicles-I (NGV-I) – The big ones (known as NGV nozzles, in popular parlance).

NZS Nozzles fitted with auto rickshaws and cars were considered the cause of long filling time due to their smaller size of in-let as compared to International Standards of NGV –I fitted nozzles as per IGL observations before the Supreme Court on 12.4.2001. Hence the court ordered that the CNG-vehicles be fitted with NGV–I nozzles at the initial stage, because replacement of NZS nozzles with NGV-I nozzle is neither scientific nor economical. In addition, NZS nozzles are in appropriate mainly because of frequent o-ring (rubber valves) failures getting cracked or losened. Sometimes, it is as high as two to three valves every minute. It happens this way the attendant insert the spout into the inlet nozzle of the vehicle. After a while there is cracking sound followed by the hissing of gas leak. The man quickly takes the nozzle out in his hand and replaces the rubber valve which happens due to pressure and heat.

The main cause of long filling time of CNG vehicle is low pressure supply which needs improvement and not only the cause of NZS nozzle.



  1. Maintenance of CNG system is very important for effective and efficiency of the vehicles.
  2. Cylinders, if genuine, are near fool proof, but despite that if the safety valve is not closed properly, accident can occur. It is, thus, desirable to keep a watch on the safety valve.
  3. To add injury to insult, the Explosives Act prohibits replacing empty gas cylinder in the buses with retro-fitting one.
  4. CNG cylinders are got to be tested and certified for use after every five years.
  5. Maintenance of the CNG kit is vital. If they are not maintained properly, they might trigger mishap any time.
  6. CNG kit and cylinder be got tested from approved work shops having details for cylinders, make number and retesting data etc.
  7. A system be devised so that vehicles going to filling stations would be checked for a safety norms. No doubt this may require extra two to five minutes but this is required till the operators are conversant and aware of the CNG routine maintenance.
  8. Approved work shops be developed in the entire city for attending CNG run vehicles.



The current CNG regulations only require that converted buses should meet the emission standards meant for diesel/petrol vehicles of their year of manufacture as per notification dated 9th Feb. 2001 of the Ministry of Road Transport and Highways. These standards need revision because tighter emission standards for gaseous pollutants for converted as well as retrofitted buses can be laid down.



The companies which are authorized by the Delhi Government for manufacturing new CNG vehicles, retro figment and conversion to CNG mode for various types of vehicles along with their cost for various jobs are given in table: I (Annexure). The cost of various jobs included in the table I of the companies may needs correction on current market trends with reference to company’s notification.



Indraprastha Gas Limited which is a joint venture company of Gas Authority of India (GAIL) Ltd., Bharat Petroleum Corporation Ltd., and the Govt. of Delhi is the only company responsible for supply of CNG for Delhi Transport System.

Infrastructure development for supply of CNG in the city of Delhi has a vital role for efficient CNG transport system. Under distribution net work IGL set up Mother stations, on line stations, Daughter booster stations, daughter stations for proper dispensing of CNG through out Delhi. The purpose of these stations are briefly discussed hereunder: -

Mother Station: A station, which is attached to the gas pipe line and which delivers CNG at a pressure of 250 Bar to Cascades.

On line Station: A station which is on line and has a smaller compressor to deliver CNG to vehicles at 250 bar.

Daughter booster station: A daughter station with its own compressor (Booster).

Daughter station: A station which receives a cascades (CNG tank) from a Mother Station


The biggest compressors which are installed in mother stations have a flow rate of 1100 kg per hour. For on line stations, a smaller compressor is used which can fill 250 kg per hour. Both these compress the gas up to 250 bar pressure and can serve two dispensers at one time i.e. they can help to fill up four vehicles at one time (one dispenser is used to fill two vehicles). Therefore, lack of adequate number of compressors in a dispensing station can result in the dispensers becoming non-functional. There is an other type of compressor called booster, which is used only in daughter station to increase the pressure of the gas, when pressure in a Cascade drops to about 180 bar from the required filling pressure of 200 bar while dispensing gas. In the absence of booster, it is not possible to dispense gas once the pressure level falls to 180 bar and then this Cascade has to be changed.

A study done by IGL in Daughter Station without booster in Delhi connecting three wheelers showed the following effect of low pressure with reference to filling of the cylinders




Pressure observed

CNG filled in kg

Filling time in seconds

200 bar

3.5 (full)


180 bar



165 bar



150 bar




At the pressure of 150 bar it is not feasible to fill the cylinder any more and the Cascade is to be changed and replaced with a new one. In other words, once the pressure drops in a Cascade of a Daughter Station, very little gas gets filled up in the vehicle’s cylinders. It means that the efficiency of the dispensing CNG at daughter station would depend on the number of cascade available of adequate pressure. As learnt there are only 120-125 Cascades for 47 Daughter Stations in Delhi @ approximate 3 Cascades for each Daughter Station. Out of these 3 Cascades only one Cascade is in use, other is getting filled up at Mother Station and the third is in the transit. There are 74 dispensing stations for supply of CNG in Delhi, the location of which is given in table 2 (Annexure).

Perusal of table 2 reveals that the distribution of dispensing stations is not spread out uniformly in the NCT of Delhi. It is proposed to set up 50 more dispensing stations at the existing petrol pumps where the land is available. By Sept. 2001 there is a proposal to increase the dispensing stations from 74 to 87 and to convert 9 existing Daughter Stations into Mother Stations. Implementation of the scheme in pipe line would give a great relief to the CNG vehicle operation. There are ten CNG dispensing stations which are running on generators in the lack of electric power. A polluting fuel is being used to supply non polluting fuel clearly shows the lack of planning. Now IGL is planning to purchase gas engine generated mechanically compressors.

Along with infrastructure development, the Ministry of Petroleum and Natural Gas, Govt. of India has to increase the allocation of natural gas for meeting the demand of CNG transport of Delhi, so that, there is no deficiency of CNG for smooth and efficient running of transport system of Delhi.



Diesel supply in Delhi has 0.05% sulphur content. Although, it meets Euro II standards, but it is not defined as environmentally acceptable fuel.ULSD (Ultra-Low- Sulphur- Diesel) with 0.003-0.001 % of sulphur content, when used with exhaust fitments like Catalytic-Regeneration-Trap (CRT) Gadget similar to a catalytic converter, which cost much more, is an environmentally acceptable fuel. A major problem in use of the ULSD is that the adulteration can not be ruled out in this fuel which makes the ULSD environmentally unacceptable. As of now ULSD is not available in the country, then, either we have to import or upgrade the existing refineries. India being a developing country is neither in a position to develop the advance technology for upgrading its refineries to be able to produce ULSD nor the capacity to import from the other countries.



According to Sh. Bhurey Lal Committee’s report, submitted to the Hon’ble Supreme Court in July 2001, Electricity is the only clean fuel, whereas, CNG, LPG and Propane gas fuels are categorized as environmentally acceptable fuels.

Conventional hydro carbon fuels are inherently polluting. Be it CNG, LPG, Diesel or Petrol. These can not be regarded as clean fuel, as they produce exhaust emissions. Among these hydrocarbon fuels, (CNG, LPG and Propane) are much less polluting then long chain hydrocarbon fuel (Diesel and Petrol). Short chain hydrocarbon fuels have a lesser percentage of carbon as compared to long chain counterparts.

CNG has one carbon atom while LPG has up to three carbon atoms. Diesel and petrol have as many as 17-18 carbon atoms, which makes them more polluting then these gaseous fuels.

There are some confusion that CNG emits even finer particles then diesel, which have greater propensity to enter the lungs which are dangerous. It is added that particles come from all kinds of combustion sources. It is the toxicity of particulate emissions that help to prioritize the control of emissions. Particulate emissions from diesel vehicles are tiny and are quoted with extremely toxic chemicals called polycyclic, aromatic hydrocarbons (PAH). Some of which are known to be the most caricinogenous. Compared with diesel vehicles, CNG vehicles emit negligible amount of particles. Moreover, even this little particle that are emitted by CNG vehicles are not as toxic as particles emitted by diesel vehicles as CNG is composed of mainly methane gas (CH4).

ULSD is also environmentally acceptable fuel with 0.003-0.001 % of sulphur content, which is not available in the country and its production is also not feasible.

In view of the above, CNG is considered more cleaner then other gaseous fuel and is also environmentally acceptable.



Some sections of the transporters/operators are of the view that multi fuel/bi-fuel vehicles be allowed which is not considered desirable.

Some dedicated (single fuel) vehicles can be optimized to take advantage of the unique attribute of the particular fuel resulting in fewer emissions, more power and less cost, a quick transition to single fuel vehicle would be highly superior to prolong reliance on inherently interior multi fuel vehicles.



Delhi is one of the most polluted City in the world, where over 3000 metric tonne air pollutants are emitted every day. The strictest feasible emissions control can not substantially reduce the alarming situations till the petroleum is used as a transport fuel.

There is no clean fuel except electricity. CNG, LPG and Propane are gaseous fuels and environmentally acceptable.CNG is totally safe. It is non-toxic, non-corrosive and non-carcinogenic (totally free from cancer inducing agents). It is cheap and easily available due to availability of HBJ gas pipeline. Petroleum vehicles can be easily and effectively converted to CNG mode vehicles. India is the first country in the world, which has succeeded for conversion of diesel engine to CNG mode.CNG and LPG are the legal transport fuel gases.CNG technology with distributor based ignition system is a first generation system, which is an obsolete technology and dangerous. CNG advance technology is third generation distributor less ignition system, which is computer-controlled system. There is an urgent need to notify safety norms for CNG run vehicles otherwise the violators will go scot-free. Emission standards for CNG run vehicles be finalized and notified at the earliest. For healthy competition, there is a need to register and approve more manufacturers/companies for providing CNG run vehicles and their components. Infrastructure development for adequate and efficient supply of CNG needs priority. Allocation for CNG be raised for NCR.ULSD (Ultra Low Sulphur Diesel) is also an environmentally acceptable fuel if the sulphur content is in between 0.003-0.001 % and when used with fitment. Its production on commercial basis is uneconomical.






Vehicle type

CNG Mode


Ashok Leyland


Retrofit (I)

Pre Euro Bus: Rs.5,98,320 (inclusive of sales tax) Euro 1 Bus: Rs.6,88,338/ (Inclusive of sales tax)




Retrofitment labour charges: Rs.45-50,000



CNG Chasis

Rs.10,37,415 +sales tax of 1,24,439.80 (@ 12%) = Rs.11,61,904.80 (Inclusive of sales tax)



Retrofit (Company has not yet started retorfitment work, this proposal is in pipeline

Rs.7,25,000 + Applicable tax in Delhi



CNG Chasis

Rs.10,29,000 + 1,23,480 (@ 12%) = 11,53,000 (according to Tata Sales and Services, New Delhi)

Hindustan Motors

RTV (mini bus)

New CNG vehicle

Rs.4,70,000 (on road HM RTV)

Bajaj Auto Ltd



Rs.89,000 According to a Bajaj Auto Dealer the CNG autos are only available through replacement of old petrol autos at STA office at Burari, Petrol autos are not sold in Delhi right now)

Nugas’ Technology Ltd.



Rs.4,86,000(inclusive of sales tax)

Rates Fuel & Automobile Technologies



Rs.3,49,000 (inclusive of all tax)

VIP- Build Con



Rs.3,30,000 – Type approval


Taxi/Petrol cars


Rs.35,440 (inclusive of sales tax)




Additional 10,000 for MPFI engine cars

Shrimankar gas service



Rs.22,700 (inclusive of sales tax)






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