The decision to advance the supply of BS-VI fuel in NCR from April 2018 to April 2020, shows the proactive approach of the Union government. But technically it is not going to help curb pollution as the vehicle manufacturers may not be able to develop BS-VI vehicles in 4 months for NCR alone. They may not roll out BS-VI vehicles before April 2020 as the vehicles have to be tested extensively.
At the same time BS-IV vehicles cannot run on BS-VI fuel, though it may be presumed that its lower sulphur content will reduce emissions. Technically the existing system does not allow it to work in that way. The engine will run with BS-VI fuel, but it will affect the sensors, electronics and the exhaust after treatment systems (EATS). For the BS-VI fuel, the electronics need to be recalibrated. Even such changes in the BS-IV vehicles, will not reduce emissions with BS-VI fuels. The process to reduce sulphur in diesel can affect the energy content of the fuel, and reduce fuel efficiency.
The proposed BS-VI fuel will limit the amount of sulphur to 10 ppm from 50 ppm in BS-IV. Normally in the diesel engines, the injectors convert the liquid diesel to a mist and spray in the cylinder. If the sulphur level in the diesel is lower, the injectors will have internal wear and scoring. This will result in uneven flow and cause incorrect and incomplete combustion that will increase emissions. Therefore, to reduce emission, both the fuel and the vehicle should be BS-VI.
Fuel quality plays a very important role in meeting the stringent emission regulation. In 2015 India had pledged to cut the intensity of its carbon emissions by 33-35% by 2030 in the target submitted to the United Nations Framework Convention on Climate Change for a global climate pact. To meet this target and combat pollution, the government should follow a holistic approach and phase out old vehicles and promote hybrid and electric vehicles with attractive fiscal incentives.
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