CNG has made Delhi's air much better: CRRI
A study by the Central Road Research Institute (CRRI) has declared compressed natural gas (CNG) as a clean fuel. According to the study, CNG-driven vehicles emit less carbon monoxide and hydrocarbon emissions as compared to petrol-driven vehicles.
The study was conducted on 846 CNG vehicles - 400 three-wheelers, 346 cars, and 100 buses - for carbon monoxide and hydrocarbon emissions. A team of CRRI scientists comprising Anil Singh, Niraj Sharma, Kirti Sharma and Chander Bhan studied new, converted and retro-fitted CNG vehicles.
The study found that cars running on CNG emitted less carbon monoxide and hydrocarbons as compared to petrol-driven cars. It says that the smaller age of CNG vehicles also contributed towards less pollution. The petrol-driven vehicles were older and this was also a factor in these vehicles causing more pollution.
According to the study, CNG three-wheelers which had four-stroke engines performed better than their petrol-driven counterparts with two-stroke engines. The difference in emissions is reported to be phenomenal.
One of the reasons for less pollution by the CNG three-wheelers was because of the four-stroke engine technology. The scientists, however, say that because three-wheelers constitute only three per cent of the total vehicles in Delhi, the consequent improvement in the air quality would be marginal.
The study found that nearly 80 per cent buses had less hydrocarbon emissions as compared to diesel buses. Also, the hydrocarbon emissions were less than the limits set by the government.
The study also found that most CNG vehicles were able to burn the fuel efficiently and very little fuel was left unburnt. The study says: "At present, only a small fraction (1.5 per cent or 45,000 vehicles) of the total 35 lakh vehicles are operating on CNG. There is no doubt that CNG is a cleaner and comparatively environment-friendly fuel as far as carbon monoxide, hydrocarbons and carbon dioxide are concerned."
The scientists say the present number of CNG vehicles are too less in numbers to have a significant improvement in the air quality. The study suggests: "Improvement in air quality is not envisaged unless suitable measures are taken to target the private vehicles in the city."
The study also took into view the fact that private vehicles constitute about 90 per cent of the total vehicles on Delhi roads. Private vehicles include two-wheelers and cars and unless emissions from these vehicles are controlled, pollution-control strategies in the city will only be partially effective.
The march for clean air began in 1997-98 with the introduction of unleaded petrol and catalytic converters. A few years later, low sulphur diesel was introduced and adulteration of fuel was checked stringently.
Emission norms for vehicles were steadily raised as a result of which, car manufacturers had to go in for MPFI engines.
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