The Hindu Business Line : Euro versus Bharat norms

THE recent news that Maruti Udyog has rolled out Euro-III compliant cars is a welcome sign that the automobile industry is catching up with the global standards. Euro-III is nearly equivalent to Bharat Stage-III, which is the vehicular emission standard proposed by the Union government and to be effective from April 2005 in identified metropolitan cities having substantial vehicle population.

This recommendation is based on the Mashelkar committee report for the auto-fuel policy launched in the country for improvement of air quality. In 2010, Bharat Stage-IV equivalent to Euro-IV is envisaged. These norms are introduced such that the change over is gradual and smooth — first in metros and after a gap of specified time, extended to vehicles plying all over India.

It seems appropriate at the outset, to take a close look at these graduating vehicles and assess their efficacy technologically in controlling air quality standards of our nation.

Transition to Bharat norms

The harmful emissions, which are identified for regulations in different Bharat Stages (BS), are carbon monoxide (CO), unburnt hydrocarbons (HC) and Nitrogen Oxides (NOx). The Table gives the prescribed upper limits. Note that HC and NOx are separately controlled in BS III, while they are bracketed in the BS I and II.

Emission limits for passenger cars are expressed as mass emissions grams per km (g/km) of simulated vehicle drive. The emphasis here is on simulation of actual driving versus assumed driving pattern in a cycle based on long observation and trials on road. In simulation, the vehicle is "exercised" on a "tread mill" called chassis dynamometer replicating the assumed driving-pattern of the country. This is called the driving cycle of the country. The emissions are measured over the cycle and the results computed to give mass emissions.

In European countries the regulatory standards are called the Euro Norms — designated by the letters EU suffixed by numerals I, II, III and IV in the increasing order of stringency. Although the norms for vehicles vary from country to country reflecting the differences in traffic density and regulation, road infrastructure, fuel quality, maintenance standards, India uses Euro standards with only one modification — lower maximum speed of 90 km/h in the last part of the cycle instead of 120 km/h as mandated in the EU norms. This cycle is called modified European cycle.

The other components of the driving cycle such as idling period, acceleration and deceleration rate and periods, cruising period are exactly the same as Euro practice. The norms derived from this cycle are called Bharat Stage standards — designated by the symbol BS suffixed by numerals in the increasing order of stringency.

According to the Table, the main requirements for BS III graduation are lower HC and NOx levels, which are now mandated separately. Probably, these are controlled by a higher and/or different catalyst formulation (to oxidise HC in the exhaust) and selected dosage of exhaust gas recirculation (preventing excessive formation of NOx). Naturally, the customers have to meet this extra cost.

The low emission level in BS III norms is only a necessary, but not sufficient, condition. For complete equivalence, some more provisions need to be made. One such provision is the on-board diagnostic system (OBD) that can indicate malfunctioning of emission control and engine performance. With this and other specified add-on systems, complete graduation to Euro-III level can be attained.

Efficacy of graduation to Bharat norms

This progress in technology has certainly established India's capability in developing cleaner vehicles and components. Using standards equivalent to the Euro levels certainly encourages export of Indian products.

Such components as catalytic converters, electronic fuel injection devices and design capability for developing cleaner combustion chambers should soon attract the attention of private Research and Development centres and institutions for more collaborative efforts.

One has also to reflect on the national objective of reducing pollution. The country has simply adapted the European cycle to the Bharat cycle by just reducing the maximum speed in the last phase.

Will this modification alone give sufficient justification to simulate the randomness of frequent acceleration and deceleration and long periods of idling, which are prone to excessive discharge of exhaust emissions?

In fact, the Indian Driving Cycle (IDC) developed by the ARAI after long-term effort is a more realistic approach. The two-wheeler industry recognised the merit of this and the IDC has become the preferred cycle used to establish emission norms for these vehicles.

We should no doubt conform to Euro standards for export purposes, but for domestic market our own norms may be relevant.

By adopting emission norms based on driving conditions abroad, there is a danger of willy-nilly getting tagged to foreign markets.

The necessary component required for upgradation to the emission norms is a three-way catalytic converter (TWC) to destroy all the three emissions (HC, CO and NOx) in a single step. This has close correspondence to an electronic fuel injection (EFI) system through a "Lamda" or oxygen sensor in exhaust with a feedback to correct the air-fuel ratio for complete destruction of the emissions.

Very little experimental evidence is there to show how fast this acts in the "stop-and-go" driving pattern of India. Yet, Euro-norm compliance requires this expensive item in EFI systems as carburettor is replaced as per BS II norms. Most of these devices and sensors are imported.

Our equipment manufacturers may have to get them tested elsewhere if facilities are not available at the authorised testing centres.

India must urgently use innovative methods to arrive at mass emissions under actual service conditions. SAE literature gives many such methods, some of them from Indian students. After rationalising these methods we may arrive at appropriate norms in a way equivalent to the Euro norms.

The ultimate aim is that mass emissions to atmosphere must not exceed the values recommended by international standards. For export purposes however we have to comply with Euro or any other norms acceptable in the foreign market. We have to balance the market forces and the societal objective of keeping our air cleaner.

(The author is a former Professor at IIT Madras and can be contacted at bsmurthy@saeindia.org)

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