Traditionally, technological trends the world
over had favored petrol engines for the lighter passenger cars and diesel
engines for the heavier trucks and buses. Petrol engines are lighter and
quieter, and capable of developing more power, making them an ideal choice for
the lighter vehicles such as cars. They are high-revving and have better power
to weight ratios and have nippy acceleration. Diesel engines are heavier and
noisier, but capable of developing more torque, making them an ideal choice for
the heavier vehicles such as trucks and buses. Diesel engines are low-revving
and have better torque to weight ratios, and have greater moving force. Modern developments in engine technologies,
however, upgraded the diesel engine to greater efficiencies, suitable for
lighter vehicles too. Europe has pioneered this light diesel engine
technological revolution, as evidenced by France having 77 percent of cars as
diesel driven, followed by Germany at 44 percent. Japan with its passion for
clean and quiet environment has been a great respecter of petrol engines; Japan
has only 2 percent as diesel driven cars. US has been at the other extreme,
encouraging use of gasoline even for trucks and buses.
Emission gap
India is on BS IV for emission norms, considered aligned with Euro IV emission regulations. The point to note is that while India is yet to achieve a nation-wide coverage of BS IV norms, Europe has already implemented Euro 5 norms and is committing to deploy Euro 6 standards by 2014. Diesels have more stringent CO standards but are allowed higher NOx emissions. That is undergoing a significant squeeze. In respect of diesel engines, CO limits have been reduced to 0.5 gms per km in Euro 4 itself while NOx limits have been reduced from 0.25 gms per km in Euro 4 to 0.18 gms per km in Euro 5 and as low as 0.08 gms per km in Euro 6. In fact, NOx limits for diesel engines are now almost on par with those of petrol engines, indicating the huge strides diesel engine technologies would need to take meet the futuristic emission norms. In contrast, BS IV norms are yet to be rolled out beyond the National Capital Region and 13 major cities. If India takes the lead to leapfrog to Euro 6 norms, in respect of both diesel and petrol engines, clearly there would be a transformational change in the emission scenario of India.
Holistic approach
The increasing share of diesel engines in the Indian passenger car industry and the emission implications thereof can only be inadequately and somewhat improperly countered by manufacturer-driven price premiums on government driven additional taxation on diesel cars. The fuel pricing differential must be moderated and subsidies by the exchequer on fuel bills reduced. This would be a better option than keeping the subsidies on and seeking additional tax revenues. Manufacturers should be incentivized to invest in superior diesel and petrol engine technologies that meet first Euro 5 norms, and then Euro 6 norms, which should be introduced as early as possible with all-India applicability. The use of ultra low sulfur fuel must extend across the nation. And, most importantly, the nation as a whole, the governments as well as the society, must wake up to the urgent need to curb the menace of rampant atmospheric dust pollution.
Posted by Dr CB Rao on January 7, 2013
India has, surprisingly, already 49 percent of
its cars as diesel driven cars. The equal share of diesel prime movers in India
has not been due to contemporary diesel engines, until at least the recent
years. The share of diesel engines in passenger cars has been driven almost
entirely by the differential pricing of petrol and diesel, with the former
being more or less market driven and the latter being administered, ostensibly
to keep the truck and bus transportation costs low. The oil industry/the
government loses roughly Rs 26 per liter of diesel, which is also approximately
the cost saving per liter of diesel. Notwithstanding the noisy and dated
technologies, diesel driven vehicles have started gaining popularity in India.
Today, no utility vehicle (UV) in India comes with a petrol engine option while
passenger cars, even smaller hatchbacks, also have taken to offering diesel
engines predominantly. This has, not surprisingly, led to a public debate on
the entire gamut of fuel pricing, vehicle taxation and use of diesel engines in
automobiles.
Public debate
Diesel engines emit darker smoke with higher
particulate matter. As if this was not enough, diesel exhaust was classified by
World Health Organization (WHO) in 2012 as a class 1 carcinogen, placing it in
the same toxic bracket as tobacco smoke. A recent All India Institute of
Medical Sciences (AIIMS) study found growing incidence of lung cancer in
non-smokers in Delhi. The study hypothesized that exposure to diesel exhaust
fumes could be one reason. The environmental voice against the dieselization of
cars is forcefully heard from Centre for Science and Environment (CSE) chief
Sunita Narain, who states “it is immoral of the auto industry to create demand
for a fuel that makes oil refineries bleed and our lungs explode”. She argues
that diesel has to be a confined as a fuel for public utilities. Some experts
have proposed higher taxes for diesel cars, in terms of higher excise duty,
annual tax on diesel cars and so on. Others have proposed total decontrol of petrol
and diesel prices. Diesel pricing, being a politically sensitive issue, no
major change in differential pricing may be expected anytime soon.
The public itself seems indifferent to the
debate on the risks of diesel engines and continues to favor diesel engines. A
diehard petrol car maker like Honda is now forced to introduce for India a
diesel car named Amaze. The automobile industry says that passenger cars are a
small contributor for the air pollution on the roads, laying the blame on the
aged commercial vehicle population of the country. It also maintains that
consequent to the change from Bharat Stage III (BS III) emission norms to BS IV
emission norms, the permissible particulate matter discharge has been brought
down from 0.5 grams per kilometer to 0.025 grams per kilometer in diesel cars.
Non-introduction of BS IV norms across the country is frowned upon by the
industry experts. Lack of smog in Europe, which runs predominantly on diesel
engines is pointed out in defence of smoggy pollution of India being caused by
factors other than diesel cars.
A recent Central Pollution Control Board
(CPCB) study threw up important findings. According to the study, vehicles
contribute only 6.6 percent to particulate emissions (PM) in Delhi. Road dust
is the biggest contributor at 52.5 percent while industries contribute 22
percent and geography 19 percent. The contribution of road dust to PM pollution
is a rampant concern across India. The sharp rise in PM10 (respiratory
particulate matter) levels and the NOx (nitrogen oxide) levels are both
attributable to public and industry apathy, it looks. Even with BS IV norms,
the diesel emission levels are still far more than those of a petrol engine.
Public and regulatory options must recognize the operating fuel price
incentives available for preferring diesel cars and the lack of incentives for
producing more efficient and environment-friendly diesel engines and cars .
While the equalization of diesel and petrol pricing is a policy option with
several undertones, the automobile industry and the oil industry must take the
lead for technological solutions.
Engine technologies
The key to finding the right driving and
emission options lies in the engine technologies. Diesel engines which are
compression ignition engines have to be more rugged (bulkier, heavier and
noisier), with the engines designed to meet the pressures needed to compress
air to diesel ignition temperatures. This is compounded by the need for precise
injection of diesel fuel in each of the cylinders. The introduction of common
rail diesel system in diesel engines coupled with electronic injection of fuel
has resulted in better combustion efficiency and better combustion balance
across cylinders. These developments need to be pursued further to ensure more
complete combustion of the diesel fuel. The injection technologies themselves
need to be sharpened to ensure greater micro-mixing of fuels. The engine
technologies, coupled with ultra-low sulfur diesel would help the efficiency
cum emission cause. The choice of diesel engines currently available in India
for passenger car applications is too small to evoke these competitive
technological forces. Indian
manufacturers and the collaborators/parent corporations would need to bring in
their best of diesel engine options to India to reposition the diesel engine
technology based on performance and emission levels rather than on price and
cost basis.
Ultra low-sulfur diesel
Ultra-low
sulfur diesel (ULSD) is diesel fuel with 15 parts per million or lower sulfur
content. The US Environmental Protection Agency (EPA) requires 80% of the
highway diesel fuel refined in or imported into the United States (100% in
California) to be ultra-low sulfur diesel. One hundred percent was mandated to
be ULSD nationwide by 2010 in USA. Ultra-low sulfur content in diesel fuel is
beneficial because it enables use of advanced emission control technologies on
light- and heavy-duty diesel vehicles. The combination of ULSD with advanced
emission control technologies is sometimes called "clean diesel". Nitrogen
oxides and particulate matter are the two most harmful diesel pollutant
emissions. These emissions can be controlled with the use of catalytic
converters and particulate traps. However, sulfur—in amounts that used to be
allowable in diesel fuel—deactivates these devices and nullifies their
emissions control benefits. Using ULSD enables these devices to work properly.
In India, the national capital Delhi first introduced ULSD on April 1, 2010 as a step aimed at curbing
vehicular pollution in the capital. However, the rollout of ULSD elsewhere as
also modernization of the fleet on the roads or the use of pollution control equipment
have been tardy, nullifying the potential benefit of ULSD.Emission gap
India is on BS IV for emission norms, considered aligned with Euro IV emission regulations. The point to note is that while India is yet to achieve a nation-wide coverage of BS IV norms, Europe has already implemented Euro 5 norms and is committing to deploy Euro 6 standards by 2014. Diesels have more stringent CO standards but are allowed higher NOx emissions. That is undergoing a significant squeeze. In respect of diesel engines, CO limits have been reduced to 0.5 gms per km in Euro 4 itself while NOx limits have been reduced from 0.25 gms per km in Euro 4 to 0.18 gms per km in Euro 5 and as low as 0.08 gms per km in Euro 6. In fact, NOx limits for diesel engines are now almost on par with those of petrol engines, indicating the huge strides diesel engine technologies would need to take meet the futuristic emission norms. In contrast, BS IV norms are yet to be rolled out beyond the National Capital Region and 13 major cities. If India takes the lead to leapfrog to Euro 6 norms, in respect of both diesel and petrol engines, clearly there would be a transformational change in the emission scenario of India.
Holistic approach
The increasing share of diesel engines in the Indian passenger car industry and the emission implications thereof can only be inadequately and somewhat improperly countered by manufacturer-driven price premiums on government driven additional taxation on diesel cars. The fuel pricing differential must be moderated and subsidies by the exchequer on fuel bills reduced. This would be a better option than keeping the subsidies on and seeking additional tax revenues. Manufacturers should be incentivized to invest in superior diesel and petrol engine technologies that meet first Euro 5 norms, and then Euro 6 norms, which should be introduced as early as possible with all-India applicability. The use of ultra low sulfur fuel must extend across the nation. And, most importantly, the nation as a whole, the governments as well as the society, must wake up to the urgent need to curb the menace of rampant atmospheric dust pollution.
Posted by Dr CB Rao on January 7, 2013
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