Atmospheric emissions from road transportation in India

India has become one of the biggest emitters of atmospheric pollutants from the road transportation sector globally. Here we present an up-to-date inventory of the exhaust emissions of ten species. This inventory has been calculated bottom-up from the vehicle mileage, differentiating by seven vehicle categories, four age/technology layers and three fuel types each, for the seven biggest cities as well as for the whole nation. The age composition of the rolling fleet has been carefully modelled, deducting about one quarter of vehicles still registered but actually out-of-service. The vehicle mileage is calibrated to the national fuel consumption which is essential to limit uncertainties. Sensitivity analyses reveal the primary impact of the emission factors and the secondary influence of vehicle mileage and stock composition on total emissions. Emission estimates since 1980 are reviewed and qualified. A more comprehensive inspection and maintenance is essential to limit pollutant emissions; this must properly include commercial vehicles. They are also the most important vehicle category to address when fuel consumption and CO2 emissions shall be contained. & 2009 Elsevier Ltd. All rights reserved. 1. Emissions from road transportation in India rising Emission inventories provide essential input data for modelling the atmospheric composition and subsequent impacts e.g. in terms of air pollution and radiative forcing. Particularly uncertain are emissions from countries in transition, for instance from India. This country has the second largest populations of the world and its gross domestic product has almost doubled between 1995 and 2005 (IMF, 2008). In the same period, the sales of motorised two wheelers and cars have almost tripled (SIAM, 2006 and 2008). This strong motorization has caused increasing concerns about local and long-range air pollution, its impacts on climate change and on the global demand for oil. Indeed, already by the year 2000, India was among the ten countries with highest exhaust pollutants from the road transportation sector (Borken et al., 2007) and road fuel consumption approximately doubled every ten years since 1980. Due to this rapid growth and the related technological changes previous emission inventories quickly outdate. Here we present a comprehensive emission inventory for road transportation in India in the year 2005. It is based on a thorough review of available data, own literature and field research, and interviews with Indian experts. We construct a consistent data base for the running vehicle fleet, their average annual mileage, fuel efficienll rights reserved. x: +97711660360. rken-Kleefeld, J., Atmosphe cies and emission factors; the data is differentiated by 7 vehicle categories, 3 fuel types and 4 age/technology levels for both the seven most populated cities as well as the whole nation. We have treated passenger and freight transport at the same level of detail and hence also included tractors as conventional means of rural transportation. Thus we go substantially beyond current knowledge with a finer differentiation of the vehicle technology, a larger scope of ten pollutants and the regional disaggregation while being consistent and up-to-date. This differentiation is necessary for any informed and quantitatively relevant action. Moreover, our bottom-up calculation serves to delimit uncertainties in regional and global emission inventories, and is necessary for modelling future changes. 2. Previous emission estimates There are a number of estimates for emissions from road transportation in India. Details of reference years, methods and input data of the previous works are presented in Table 1. They take either fuel consumption or vehicle mileage as activity data, i.e. follow either the basic Tier 1 or the more sophisticated Tier 2 approach according to IPCC (1996). Various aspects and discrepancies become apparent in a closer inspection of the emission estimates: Road transport has at least doubled its CO2 emissions from 57 to 70Tg in 1990 to 134 to 220Tg in 2005 (Fig. 1a). This growth rate is similar in all emission estimates, but a spread of about 10–20Tg in calculated CO2 emissions has not ric emissions from road transportation in India. Energy Policy