April 07, 2020
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Fuel Feud

Even as automakers climb on the diesel bandwagon, greens say oil-burners are more harmful

Fuel Feud

A Tata Indica advertisement seduces with more. More power. More space. More style. With these three come-ons and a competitive price tag to boot, Ratan Tata should be laughing all the way to the bank.

But not if some environmentalists have their way. Because it runs on diesel also. And diesels, the greens say, belch out more noxious emissions than petrol engines. In fact, the Environment Pollution (Prevention) Control Authority (epa), a statutory body set up by the Supreme Court to help Delhi combat air pollution in the National Capital Territory (nct), recently proposed a ban on registration of diesel cars in Delhi.

But Telco and others - notably Mahindra and Mahindra, Hindustan Motors and Ind Auto - have decried the proposal, saying claims of pollution from diesels are exaggerated and that petrol cars are as polluting. They extol diesel cars as the future of the automobile industry, citing rising sales in Europe. Diesel vehicles consume less fuel, emit less carbon monoxide (CO) and hydrocarbons and meet emission norms for year 2000. Why ban them? asks Rajat Nandi, executive director, the Association of Indian Automobile Manufacturers (AIAM).

Precisely. Why only in Delhi and why only diesel cars? Why not petrol cars which are hardly above board? If the aim is to have cleaner air, why not look at other options like better traffic management, fuel quality and roads and stringent enforcement of emission norms? Will the ban have any impact on air quality? Lets examine why diesel cars are undesirable for Delhi.

What makes Delhi the world's fourth most polluted city? The large amounts of noxious particles spewed into the air by factories and vehicles. While industry emits over 60 per cent of the suspended particulate matter (SPM), soot particles from smokestacks are not small enough to penetrate the respiratory system. But particles from diesel engines, less than one-millionth of a metre in diameter, can penetrate deep and cause asthma and bronchitis. Prolonged exposure could even mean lung cancer.

Diesels emit more nitrogen oxides (NOXs), which react with hydrocarbons to create ozone, the chief ingredient of photochemical smog. Ground-level ozone is known to aggravate asthma and other ailments.

  • Unlike petrol engines, diesels give their best at full load. Since in a city one never drives at full capacity, diesels emit more particulates, says H.B. Mathur, a former professor of mechanical engineering at IIT, Delhi.
  • Diesel in Delhi has a high sulphur content, 0.25 per cent as against 0.001 per cent in Sweden and 0.05 per cent in the rest of Europe. Diesel in the rest of India has between 1 and 3 per cent. More sulphur means more particles and also more sulphur dioxide, which leads to acid rain. T.S. Vijayraghavan, secretary, ministry of petroleum and natural gas, is not very optimistic about improving fuel quality further: Weve already spent about Rs 10,000 crore in providing unleaded petrol and low-sulphur diesel to the metros. Weve no money for any improvements in fuel quality.
  • There are no appropriate emission standards for small diesel cars coming in, says Anumita Roychowdhury of the Centre for Science and Environment. Emission norms have been notified only for two broad diesel categories: heavy vehicles of over 3.5 tonnes and light commercial vehicles. The 2000 emission standards for both classes are the same for all exhaust gases except for particulates. This means a car is allowed to emit as much as a truck, she adds.
  • Says Mathur, Multinationals are dumping engines that cant meet stringent emission standards.The auto makers refuse to accept that Euro 1996 standards be enforced here in 2000. While the Euro 2000 norm for diesel SPM is 0.05, India's 2000 standard is 0.36. This means diesels here can pollute seven times as much.
  • Car makers exploit the heavy subsidies on diesel, meant for locomotives and agriculture. The finance ministry says diesel subsidy leapfrogged from Rs 430 crore in 92 to Rs 8,340 crore in 96. In the same period, diesel consumption rose by 42 per cent. Says Roychowdhury, The policy to keep diesel prices low to help the agricultural sector and to avoid adulteration with subsidised kerosene didn't work. The biggest benefactors have been urban consumers. Cheap diesel also favoured freight movement by road, more energy-inefficient and polluting than rail transport, whose share declined from 67 per cent in 70-71 to 47 per cent in 91-92. Why should the rich enjoy a benefit not meant for them? asks Mathur.

    Much of this is also borne out by how diesels are now perceived in the West. Last August, the California Environmental Protection Agency (CEPA) classified SPM emissions from diesels as a human carcinogen. The CEPA has announced a $25-million diesel engine replacement programme.

    More damningly, last October diesel engine manufacturers in the US agreed to pay $83 million in fines and spend $1 billion on environmental improvement to avoid a federal lawsuit over alleged cheating on engine performance tests. Manufacturers were accused of using defeat devices that enable engines to pass emissions tests at low speeds even when they exceeded norms at highway speeds. More bad press: A Swedish study of new diesel cars shows that if diesel car sales rise from the current 1 per cent of total sales to 20 per cent, NOX emissions from new cars will double and SPM emissions will be 2.5 times higher.

    While diesel cars have improved considerably over the last 10 years from their soot-belching days, petrol-driven cars have evolved faster, the study says. The problem, it adds, is that even though diesels use 20 to 25 per cent less fuel (a fact ads often stress), emission of CO2 (a greenhouse gas) is only marginally lower. Burning one litre of diesel produces about 15 per cent more carbon dioxide than one litre of petrol. Besides, diesels emit 10-15 times more SPM and 1 to 1.5 times more NOXs than modern petrol cars. If this is the case in Europe and the US, it is fair to infer that the less advanced technology in India would be more polluting.

    Reducing air pollution is a complex problem. Because it entails taking harsh economic, non-populist decisions - like phasing out old cars - policy-makers have to base their judgments on all available evidence of relative risk from different emissions. For example, deciding which is more hazardous for human health, carbon monoxide or SPM, or asking how much SPM diesel contributes.

    But such quantitative comparisons are elusive, simply because we do not monitor our air for several hazardous emissions. The CPCB doesn't monitor particles even 10 microns in diametre, let alone 2.5 microns and smaller, which comprise 90 per cent of the spm emitted by diesels. There's also no tailpipe monitoring for NOXs, sulphur oxides or benzenes, which could make the picture clearer. Only CO and hydrocarbons (often only CO) are monitored in the case of petrol, and there is practically no monitoring of emissions in the diesel exhaust.

    At any rate, opines Michael J. Walsh, World Bank consultant and formerly with the epa of the US, I don't think its wise to allow diesel cars in Delhi, which already has the highest spm concentrations. SPM from diesel is not only a human carcinogen, its the single largest cause of premature deaths. What with high-sulphur diesel, an ageing fleet of trucks, buses and taxis, and low emission standards (India's 2000 emission norms came into effect in Europe in 92), it makes no sense to promote diesel cars.

    But the government proceeds by asinine logic. Ask Mathur, who chaired the first committee that set mass emission standards for petrol vehicles. First they watered down emission norms to appease industry. Then they resorted to piecemeal solutions like catalytic convertors which are unmitigated failures. The ones fitted into new cars were originally made to work with fuel-injection systems. With carburettors, their efficiency is reduced to about 30 per cent.

    Also, he adds, while unleaded petrol may have reduced lead emissions, it has released a new poison: benzene, which is not monitored. Though the industry claims benzene content in both leaded and unleaded petrol is the same (less than 4 per cent by weight), Mathur says it increases in the exhaust. Besides, unleaded petrol contains hazardous chemicals which escape as vapour into your airways while you are happily driving, windows rolled up, under the delusion you have shut out pollution, he reveals.

    So petrol cars are certainly not benign. But that's no excuse for introducing diesel cars. They emit a different class of toxins which are even worse, says Mathur. Its true there aren't too many diesel cars in Delhi but with almost all automakers announcing diesel models, their numbers are bound to increase. Besides, thousands of outdated commercial vehicles spew large amounts of deadly emissions in the air. With not more than 10 pollution check-up points for diesel vehicles in the nct, its impossible to monitor tailpipe emissions from them.

    We can't do much about the rising army of diesel trucks and buses unless the government makes rail freight more attractive (by denying diesel subsidies to road transport) and offers a better mass rapid transport system. It can at least force the industry to upgrade ageing, polluting engines, just like in the US, suggests Mathur. He ridicules the aiam suggestion of introducing the more expensive low-sulphur diesel for diesel vehicles in Delhi. The first claimant shouldnt be the luxury cars but agriculture.

    While the government dithers, auto makers are lobbying hard against the proposed ban. In fact, last week aiam organised a seminar on fuel and vehicle technology where experts were carefully chosen from countries like France and Austria which have large fleets of diesel cars. They concluded that modern diesel engines are eco-friendly and that however good the technology, emissions cannot be reduced without better-quality fuel. But will Delhi chief minister Sheila Dixit buckle under industry pressure (or alternatively be fooled by it) or will she listen to reason and honour her pledge to rid Delhi of its deadly air?

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