Research |
Program for Computational Reactive Mechanics (PCRM)Anthropogenic
Emissions from energy activities in India:
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Contents Part I: Emissions from Thermal Power Plants using Coal as Fuel |
Part II: Emissions from Vehicular Transport using Petroleum Fuel Vehicles in India Emissions from Internal Combustion Engines Petroleum Fuels used in India Fuel Stoichiometry Engines for Vehicular Transport Exhaust Emissions Indian Scenario Emissions Factors and Available Inventory Appendix |
Emissions from Coal Fired Thermal Power Plants in India
Based on the input parameters and the ultimate analysis of coal used for power generation, emissions of CO2, SO2, NO, soot carbon and particulate matter from each of the power plants has been computed. Input parameters (operating conditions) are actual air supplied, electric power generated per day, and coal used for unit power generation. Thermal power plants also use small quantities of diesel oil and furnace oil (FO) as supplementary fuels to boost the combustion and heat content. In the thermal power plants run by National Thermal Power Corporation (NTPC), supplementary fuel consumption is 0.2 to 0.3 ml/unit of power. The supplementary fuel consumption in old thermal power plants may range from 1 to 4% of the fuel. Emissions from combustion of these supplementary fuels are not accounted in the computations at present.
For the estimation of emissions of above mentioned species from the Indian thermal power plants, the available values of the ultimate analysis of coals used in the seven thermal power plants namely Chandrapur, Dhanau, Singrauli, Dadri,Rihand, Kutch, and Nayveli, are used. Most of thermal power plants in India use E and F grade coals only. An average of ultimate analysis of E and F2 grade coals, as given in Table 6a is used for the remaining 74 thermal power plants. The excess air used in the individual power plants, kg coal used for unit (kwh) power generation, and per day power generation is available and is listed. NO calculations assume equilibrium reactions and 1700 K gas temperature. The data for the individual plants can be accessed by clicking at the power plant in Table 13 or the plant number in Figure-2.
CO2 emissions are estimated based on the carbon content in the coal and the excess air used at the power plants. 12% carbon (based on the measurement data, it is assumed that 10% carbon remains unburned and mixes with the ash and 2% carbon forms soot) is subtracted before calculating emissions of CO2. Figures 3 and 4 provide the computed data for CO2 emissions from coal fired thermal power plants assuming 88% of coal carbon to undergo combustion. Table 14 provides CO2 emissions per day from power plants.
Table 14: Computed values of CO2 emission per day from power plants
CO2 (Thousand ton) |
Number of power plants |
Coal used per day (million tons) |
40-50 |
5 |
0.16 |
30-40 |
3 |
0.08 |
20-30 |
9 |
0.15 |
10-20 |
24 |
0.3 |
0-10 |
40 |
0.43 |
Total CO2 emissions per day from all the coal fired power plants in India was 1.1 thousand tons per day in 1997-98 and annual emission has been computed to be 395 million tons. Yearly estimates of power generation and emissions are based on the plant load factor (PLF) for individual power plant. PLF is the ratio of the actual power generation and the installed capacity. Knowing the yearly power generation, the annual emissions are computed. Estimate of CO2 emission from power sector in India for 1990 is 213 million tons. CO2 emission estimates based on the present calculations seem to compare well with this estimate made for 1990. CO2 emissions per unit of electricity from power plants in tabular form are given in Table 15.
Table 15: Computed values of CO2 emission per unit of electricity from power plants
CO2 (Kg/KWH) |
Number of power plants |
1.4 - 1.8 |
4 |
1.2 - 1.4 |
9 |
1.0 - 1.2 |
27 |
0.8 - 1.0 |
40 |
0.6 - 0.8 |
1 |
Computed data indicate that CO2 emissions per unit of electricity from most power plants range between 0.8 and 1.2 kg/KWH. Some plants have between 1.2 and 1.4 kg/KWH. Four plants have CO2 emissions more than 1.4 kg/KWH. This number reflects operational inefficiency due to poor coal quality or operating conditions. One power plant has this number less than 0.8 kg/KWH.
In general the sulfur content in Indian coals compared to the US coals is low. Figures 5 and 6 show the computed data for SO2 emissions from thermal power plants in India assuming that no control technology is in use. Total SO2 emissions per day from all the power plants in India has been estimated to be 7.6 thousand tons per day and 2.8 million tons per year. Average SO2 emission per unit of electricity from Indian thermal power plants has been found to be 7.4 gm/KWH. The lignite based thermal power plants have maximum emissions for SO2 per unit of electricity generated (e.g. Kutch plant has been estimated to emit 31 gm/KWH and Neyvelli 18 gm/KWH). For coal based thermal power plants, these estimates show that Chandrapur has maximum emission per unit of electricity generated (18 gm/KWH) followed by Nellore (10 gm/KWH). Most of the other plants emit between 4 to 9 gm SO2/KWH, according to present calculations.
Figures 7 and 8 give the computed data for NO emissions. NO emissions are based on equilibrium reaction and an average gas temperature of 1700 K. This is a theoretical ideal. In reality the gas temperature in the boiler varies from 900 k to 2500 K and the reaction also occurs in several phases. Present estimates of NO emissions from thermal power plants are 7.9 thousand tons per day and 2.9 million tons per year. The Nellore thermal power plant has been found to be largest emitter of NO per unit of electricity with a value of 13.1 gm/KWH. Plants like Faridabad, Harduaganj, Tanda, Korba II&III, Kothagudem, Ennore, Barauni, Muzaffaurpur and Patratu are also amongst the larger emitter of NO per unit of electricity generated (emission ranges from 10 to 12 gm/KWH). Most of the other plants have NO emissions in range of 6-10 gm/KWH.
For the soot, present model calculations based on the assumptions given before, show that approximately 67 tons soot carbon (BC) per day or about 24 thousand tons per year is emitted from the Indian thermal power plants during 1997-98. These estimates are much lower than 608.4 thousand tons of BC emissions estimated from coal consumption in India based on average emission factor15. This has the implied consideration that the thermal power plants are the major consumers of coal in India. The emission factors arising out of the present calculations are 0.08 gm/kg of coal and 0.06 gm/kg of lignite in Indian thermal Power. This emission factor for coal is much lower than average emission factors for BC of 1.0, 0.325 and 0.2 g/kg proposed for under-developed, semi-developed and developed countries respectively14 for industrial use of hard coal, hard coal briquettes, coke, oven coke, gas coke and brown coal coke. However, Soot emission factor of 0.08 gm/kg for coal obtained from the present calculations compares well with the emission factor of 0.075 proposed for industrial use of hard coal16,17. Figures 9 and 10 show the soot (BC) emissions per day and per unit of electricity from power plants in India. The Nellore thermal power plant with an estimated emission of 0.1 gm/KWH has been found to be the largest emitter of soot. The other large emitter thermal power plants include Faribdabad, Harduaganj, Korba II& III, Kothagudem, Barauni, Muzaffarpur and Talchar NTPC where the soot emission range from 0.08 to 0.1 gm/KWH.
The ash contents in the coal consumed in the thermal power stations is responsible for the emission of 2.3 thousand tons of SPM in the form of fly ash per day and about 0.8 million tons SPM per year. Figure 11 and 12 show the SPM emission per day and per unit of electricity from power plants in India. The Chandrapur, Kothagudem, Nellore, Baauni and Muzaffarpur thermal plants have been found to be amongst the largest emitter of SPM per unit electricity. About 3 to 3.5 gm of SPM/KWH has been estimated to have emitted from these plants. The plants like Faridabad, Harduaganj, Obra, Panki, Paricha, Tanda, Korba II & III, Satpura, Ennore, Patratu, Calcutta, New Cossipore, Talchar NTPC and IB Valley TPS emit in the range of 2.5 to 3 gm SPM/KWH. Rest of the plants have SPM emissions lower than 2.5 gm/KWH.
Approximate location of major thermal power plants in India is indicated in the following map (Figure 2). Click the number to get the computed emission data for the specific power plant.
Figure 2: Geographical location of major thermal power plants in India
13Greenhouse Gas Emissions in India for the Base Year 1990: Global Change Scientific Report No 11, May 1998, Ed. S. Bhattacharya and A.P. Mitra, Centre on Global Change, National Physical Laboratory, New Delhi, India
14Mitra A.P. and Sharma C. `Indian Aerosols: Present Status'.
Under publication in the special issue of `Chemosphere - Global Change Science' based on the presentation made in `14th Meeting of the Scientific Group on Methodologies for the safety Evaluation of Chemicals (SGOMSEC-14)' 2001.
15Cooke W.F., Liousse C., Cachier H. and Feichter J., `Construction of a 10x10 fossil fuel emission data set for carbonaceous aerosol and implementation and radiative impact in the ECHAM4 model', Journal of Geophysical Research, Vol. 104, No D18, pp 22137-22162, 1999.
16Bocola W and Cirillo M.C., `Air pollutants emissions by combustion processes Bocola W and Cirillo M.C., `Air pollutants emissions by combustion processes in Italy', Atmospheric Environment, vol. 23, pp 17-24, 1989.
17EPA, Supplement B to compilation of air pollutant emission factors, vol. I,: Stationary point and area sources, Tech. Rep., Office of the Air Quality Planning and Standards, Research Trangle Park, NC, 1996.
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