Trends in multi-pollutant emissions from a technology-linked inventory for India: I. Industry and transport sectors

Emissions estimation, for research and regulatory applications including reporting to international conventions, needs treatment of detailed technology divisions and high-emitting technologies. Here we estimate Indian emissions, for 1996-2015, of aerosol constituents (PM2.5, BC and OC) and precursor gas SO2, ozone precursors (CO, NOx, NMVOC and CH4) and greenhouse gases (CO2 and N2O), using a common fuel consumption database and consistent assumptions. Six source categories and 45 technologies/activities in the industry and transport sectors were used for estimating emissions for 2010. Mean emission factors, developed at the source-category level, were used with corresponding fuel consumption data, available for 1996-2011, projected to 2015. New activities were included to account for fugitive emissions of NMVOC from chemical and petrochemical industries. Dynamic emission factors, reflecting changes in technology-mix and emission regulations, were developed for thermal power plants and on-road transport vehicles. Modeled emission factors were used for gaseous pollutants for on-road vehicles. Emissions of 2.4 (0.6-7.5) Tg y−1 PM2.5, 0.23 (0.1-0.7) Tg y−1 BC, 0.15 (0.04-0.5) Tg y−1 OC, 7.3 (6-10) Tg y−1 SO2, 19 (7.5-33) Tg y−1 CO, 1.5 (0.1-9) Tg y−1 CH4, 4.3 (2-9) Tg y−1 NMVOC, 5.6 (1.7-15.9) Tg y−1 NOx, 1750 (1397-2231) Tg y−1 CO2 and 0.13 (0.05-0.3) Tg y−1 N2O were estimated for 2015. Significant emissions of aerosols and their precursors were from coal use in thermal power and industry (PM2.5 and SO2), and on-road diesel vehicles (BC), especially superemitters. Emissions of ozone precursors were largely from thermal power plants (NOx), on-road gasoline vehicles (CO and NMVOC) and fugitive emissions from mining (CH4). Highly uncertain default emission factors were the principal contributors to uncertainties in emission estimates, indicating the need for region specific measurements.