Delhi has become the first city in India to retail Bharat Stage-VI-grade petrol and diesel. The good news is that the cleaner fuels have gone on sale without an increase in per unit price, as was expected. Interestingly, the higher-grade fuels have been made available in Delhi before the original nationwide roll-out planned for April 1, 2020, as a measure to curb the chronic air pollution problem in the national capital. Just last week, the Supreme Court also urged the government to investigate the feasibility of bringing BS-VI fuels to other metro cities before the 2020 deadline.

So what are BS-VI fuels and how do they affect you? Let’s take a look at the matter in more detail.

What is the background story?

India’s vehicle emission standards are modelled on the Euro emission standards that define limits for harmful exhaust emissions. The emission standards are primarily focused on the reduction of nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC) and particulate matter (PM) emissions. As per the Indian government’s original roadmap, BS-IV (the equivalent of Euro-IV) was to be implemented across the country by April 1, 2017, BS-V in 2019 and BS-VI in 2023. While the scheduled roll-out of emission standards put India a few years behind Europe, it did allow ample time for Indian vehicle makers and, equally importantly, fuel suppliers to upgrade and be ready to meet the requirement.

However, vehicle makers and fuel suppliers were caught off-guard by the government’s shock announcement in early 2016 of skipping BS-V altogether and bringing forward the introduction of BS-VI norms to 2020. The jump from BS-IV to BS-VI is drastic, not only from a technology standpoint for carmakers but also for the supply side as refineries have to produce compliant (read higher-grade) fuels.

What is BS-VI grade fuel?

The move from BS-IV to BS-VI primarily requires fuel to have significantly lower sulphur content. The sulphur content in BS-IV petrol and diesel is 50 parts per million (ppm). BS-VI grade fuels, however, have a sulphur content of 10ppm.

How will it affect me?

While BS-IV fuel will not be done away with altogether in a hurry, the question is, is there any advantage of running your existing BS-III or BS-IV compliant car on BS-VI fuel? The answer is, largely, yes. In simple terms, the lower the sulphur content in the fuel, the cleaner it burns. Petrol with lower sulphur emits less NOx, CO and HC, while the advantage of low-sulphur diesel is significantly lower particulate matter (PM) emissions. Estimates suggest a BS-IV-compliant car running on BS-VI diesel could emit 50 percent less PM.

On the flip side, the process to reduce sulphur in diesel can negatively impact the energy content of the fuel, and correspondingly bring down fuel efficiency, if only by a small margin. There are also concerns over the lower lubricity and readiness to burn (expressed in cetane number) of ultra-low-sulphur diesel (ULSD). Then again, ULSDs come with additives that address these issues.

When can we expect BS-VI-ready cars?

The majority of India’s carmakers have already expressed concerns on the scale of the challenge to meet BS-VI norms in 2020. As things stand, no mass-market car is BS-VI-ready. In effect, the first real beneficiaries of the higher grade fuel is the BS-VI-ready new Mercedes-Benz S 350d and other cars imported from abroad that already come built to meet Euro-VI standards, courtesy technology like diesel particulate filters. What would be interesting to see is the strategy employed by the Volkswagen Group in India that has made considerable investments to downgrade its Euro-VI-compliant 2.0-litre diesels to run on lower-grade Indian BS-IV fuel.

In the larger scheme of things, the push for cleaner fuels is welcome but the government has to take a holistic approach as it tackles the alarming air pollution in India. And no, till the time we generate clean electricity, electric cars are not the answer to India’s air pollution woes.