The use of CNG for road transport was developed in USA in nineteen seventies however, it never found its general application, only recently it is being used to a very limited extent for environmental reasons. The Hydrocarbon Institute of Pakistan in 1982 set up experimental CNG stations in Karachi and Islamabad. The two CNG stations were purchased as a package from the US. CNG was used by only a few car owners in Karachi and Islamabad till 2001-02. Thereafter, on the recommendations of the Secretary Petroleum M Abdullah Yusuf to popularize CNG, the import of CNG kits etc were exempted from duty.
Unfortunately no study was undertaken on the economic and technical aspects of this radical change in the transportation fuel policy. Before this technically unsound, economically disastrous and immoral decision the transportation fuel policy was in favour of the use of diesel for transportation. Diesel being the most economic fuel in terms of efficiency its price was always kept below the price of petrol.
The decision was immoral because the subsidised fuel was being provided to the car owners the rich elite, for which one does not see any justification, because they could afford to buy petrol. Technically it involved compressing piped natural gas from a pressure of about half a pound per square inch (0.5 psi) to about 2,500 to 3,600 psi. Interestingly the high pressure in the storage cylinder in the car has to be depressurised down to a pressure of 0.5 psi for burning in the car's engine thus all the electricity used for the compression is wasted. Furthermore the fuel efficiency of CNG is half (50 percent) of the modern diesel engines. Economically this has been disastrous, because we have wasted precious natural gas reserves and thus starved the industry and power plants of gas. This has been done to supply subsidised fuel for the cars of the rich, the "elite" and the super rich.
Diesel
The modern diesel engines consume about fifty percent (50 percent) less fuel than an equivalent petrol engine. CNG use in petrol engine cars is even less efficient. It was mainly due to the high efficiency of the diesel engines (low fuel consumption) that it has always been used in trucks, ships and railways. Europe made a technically sound and economically wise decision in favour of diesel. As a result in 2012 in European Union overall about fifty five percent (55 percent) of all cars were run on diesel. In France the figure for diesel cars is about sixty five percent (65 percent), furthermore in France in 2012 over seventy percent (70 percent) new car sales were of diesel cars. The projected estimates for 2013 EU car market are; diesel: 54.9 percent; petrol: 42.9 percent and alternative: 2.2 percent. The statistics demonstrate the technical and economic wisdom of EU.
The diesel engine was originally developed in Europe and Europe has taken the lead in research and improvement of diesel technology. Initially the research in Swiss universities invented the modern common rail diesel engine technology. In spite of this it is significant that the first common-rail engine production vehicle was introduced in Japan in mid-1990. Concurrently Fiat in 1990s developed the electronically-operated injection technology (in place of mechanical injection) for common-rail diesel engines but, due to financial problems sold the technology to Robert Bosch GmbH who completed and refined the design for mass production.
Briefly the Common-Rail diesel engine does not have any vibrations, starts cold, is noise free and consumes about 25 percent less diesel than the conventional diesel engine. It is also environmentally friendly; the carbon dioxide emission of the Common-Rail diesel engines is 139.3 gm per km compared to 142.5 gm per km for petrol engine cars. Furthermore today the Common-Rail diesel engines are the norm for almost all cars, railways, ships and trucks.
It needs to be noted that the modern Common-Rail diesel engine requires low sulfur content diesel. The present diesel in Pakistan has relatively high sulfur content. It is understood that the plans to produce EU specifications are being implemented by the refineries and marketing companies.
In my opinion the country needs to forthwith discard the unsound CNG policy in favour of diesel. The original pro-diesel policy of pre-independence days was never changed in India. In this regard it may be noted that Toyota introduced their 1400 cc Common-Rail diesel car in India a couple of years ago. This car gives an average consumption of over 20 km per litre diesel compared to about 10 km per litre by its petrol twin.
Recommendations
i) The price of CNG must be equalised with that of petrol on BTU basis thus ending the subsidy to the rich elite.
ii) Permission for new CNG stations must be banned.
iii) Price of diesel is kept less than petrol.
iv) Duty-free import of CNG kits spares and related equipment must be stopped.
v) All new railway engines must be Common-Rail.
vi) Reduction in import duty on common-rail diesel engines is required.
vii) Facilities for repair, testing and tuning Common-Rail engines be developed on a priority basis with Chinese and German collaboration.
viii) Steps need to be taken for production and import of EU specification diesel with respect to sulfur content.
Conclusion
It is estimated that if the above recommendations are implemented initially the annual increase of about 8 to 10 percent in the fuel bill for the transport sector will stop and ultimately it will be reduced substantially depending how effectively the above recommendations are implemented.
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