Clean fuels for Delhi's vehicles: the best options

From 1 April, the order of the Supreme Court of India applicable to Delhi would require the Transport Department of the state to allow only buses using CNG (compressed natural gas) to ply on the roads of the capital. In response to the petition submitted by the Government of Delhi and other affected parties, the Supreme Court would allow, for a period of six months, such numbers of diesel buses to be operated by owners equivalent to the number that they have registered for conversion to CNG and for which firm orders have been placed by them for conversion to the use of CNG. Unfortunately, no other choices have been analysed in the past, and the Supreme Court of India was provided with only the option of CNG as a fuel for improving air quality in Delhi. In actual fact, in most countries of the world there is a growing preference for ULSD (ultra low sulphur diesel), i.e., diesel fuel with .005% sulphur content, using engines fitted with suitable particulate traps. On economic, environmental, and technological grounds, ULSD is being adopted in most metropolitan areas as the preferred fuel for operation of city buses. The establishment of CNG infrastructure and the conversion of buses in Delhi would not only prove extremely expensive, but would not be the best option even on environmental terms. The approach that should be adopted early, therefore, must allow for immediate trials using ULSD, by importing the fuel, since Indian refineries have not yet started producing it. With suitable trials, citizens of Delhi would then have a choice. Meanwhile, action in using CNG should continue apace and data should be collected on the performance of buses using CNG. But it would be unrealistic to expect that ten thousand buses in the city would ever ply on the roads using CNG as a fuel. Civil society has to get involved urgently in meeting this challenge headlong, and ensuring that all available choices are considered in the ultimate decision on fuels and automobile technology.