Air Pollution Control in India: Getting the
Prices Right
Maureen Cropper, Shama Gamkhar,
Kabir Malik, Alex Limonov and
Ian Partridge
Goals of This Paper
• Estimate health damages of SO2, NOx, PM
emissions from coal-fired power plants in
India
– Calculate damages per plant based on 2008
emissions
– Calculate damages per ton of SO2, NOx, PM2.5
for each plant
• Use results to estimate benefits of two
pollution control measures:
– Coal washing (to reduce ash content of coal)
– Flue-gas desulfurization units (scrubbers)
Motivation for the Paper
• Is current emphasis on controlling directly emitted PM
misplaced?
– Pollution permit markets in Tamil Nadu, Gujarat focus on PM
• Should there be controls on SO2 emissions?
– India currently has no limits on SO2 emissions from power
plants, possibly because of low S content (0.5%)
– But, kg coal/kWh are high due to low heating value of coal and
exposed population is large
• Domestic coal has high ash content (30-50%) but only
5% of coal is washed
– What are the health benefits of coal washing?
Our Approach
• Assemble database on 92 coal-fired power plants,
1994-2008
– Plants constituted 88% of installed coal capacity in 2008
• Calculate emissions of SPM (63 plants), SO2, NOx
(68 plants) for 2008
• Predict change in population-weighted ambient
concentrations of fine particles per ton of PM2.5, SO2,
NOx emitted
– Using gridded population data around each plant
• Use Pope et al. (2002) study to predict premature
mortality from cardiopulmonary causes for adults ≥ 30
Main Results
• About 75% of deaths are due to SO2; about 20%
to NOx; 5% to directly emitted PM
– Ash content is high, but ESPs are used by all plants
• Variation across plants in deaths per ton of
pollutant is small:
– Mean deaths per 1,000 tons of SO2 = 10 (s.d. = 2)
• Coal washing reduces deaths from Rihand plant
by 20% - most due to reduction in SO2
• Cost per life saved of scrubber at Dahanu plant =
Rs. 3.55 million; 123 lives saved per year
Coal-Fired Power Plants in India
• Generate about 70% of electricity in India
• Coal burned per kWh 60% greater than in US
• Coal/kWh ≡ (Heating value of coal)/(OPHR of plant)
– Heating value of coal (3625 kcal/kg) much lower than in
the US (4400-7000 kcal/kg)
– OPHR (kcal/kWh) of plants higher than in US due to high
ash content of coal and operating inefficiencies
• Ash content of coal = 30-50% (cf. 4-5% for PRB
coal)
• Sulfur content = 0.5% by weight (PRB coal ≈ 0.4%
Illinois coal = 3-4%)
Pollution Regulations and Control
Equipment Used
• Emissions standards for TSP (SPM) are concentration
standards
– Violated by about 25% of plants for which data are available
• Ash content of coal must be ≤ 34% in sensitive and critically
polluted areas
• All power plants have ESPs, although ash content affects
their efficiency
• No limits on SO2 emissions, but
– Minimum stack height requirements
– Plants (EGUs) over 500 MW must leave space for a scrubber
• No limits on NOx emissions, but most plants have low-NOx
burners
Pollution Intensity of Coal-Fired Power
Plants: India v. US
(Lbs/MWh)
India
U.S.
Pollutant Mean (Wtd.) Mean (Unwtd.) Mean (Wtd.) Mean (Unwtd.)
PM2.5
0.43
0.50
0.49
0.59
SO2
16.2
15.7
10.1
12.3
NOx
4.73
4.61
3.42
4.09
Estimating the Impact of Emissions
on Ambient Air Quality
• Need to translate emissions into ambient air quality for each
plant
• Applying a Gaussian dispersion model (e.g., CALPUFF) to 90
plants beyond the scope of the project
• Zhou et al. (2006) ran CALPUFF for 29 identical power plants
in China, in different locations
• Change in population-weighted ambient concentration of
sulfates per ton of SO2 emitted related to population in
concentric annuli around each plant and annual precipitation
• These equations used to predict the change in populationweighted ambient concentrations at each plant, based on
gridded population data and precipitation data for India
Population covered within 100km radius from power plants
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Coal based power plant
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Population (2005)
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Up to 10,00,000
10,00,001 - 25,00,000
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25,00,001 - 50,00,000
50,00,001 - 75,00,000
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More than 750000
Population covered within 100km radius from the power plants
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Estimating Health Effects
• Only a few time series, no cohort studies linking
air pollution to mortality in India
• Time series studies find similar magnitudes of
effects of PM on mortality as NMMAPS (US) and
APHEA (EU) studies in spite of higher ambient
concentrations in India
• We transfer results from Pope et al. (2002) for
cardiopulmonary mortality
• Estimates capture impacts of fine particles on
deaths over 30; no impacts on under-30 mortality
or morbidity
Distribution of Deaths per Plant,
by Pollutant
Deaths (All pollutants)
Total deaths per plant
due to
PM 2.5
SO2
NOx
Deaths per ton of
emission of
PM 2.5
SO2
NOx
# obs
Mean
Std Dev
63
659
523
63
63
63
29
499
123
43
407
95
89
89
89
0.023
0.010
0.009
0.005
0.002
0.002
Location of coal-based power plants
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Rihand
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Dahanu
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Population (2005)
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25,00,001 - 50,00,000
50,00,001 - 75,00,000
More than 750000
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Coal based power plant
10,00,001 - 25,00,000
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Coal Washing at Rihand Plant
• Assume coal-washing reduces ash
content from 43% to 35%
• This also reduces S content from 0.39% to
0.34%
• By raising heating value of coal, reduces
amount of coal used by 14%
• Coal washing raises cost of electricity
generation by 16%
Health Benefits of Coal Washing
Unwashed
Coal
Washed
Coal
% reduction due to
washing
Coal Usage (`000 tons)
10903
9322
14%
PM2.5 (tons/year)
1732
1207
30%
SO2 (tons/year)
77854
58032
25%
NOx (tons/year)
25828
25828
0%
Total Deaths
Deaths due to
1255
1001
20%
PM 2.5
43
30
30%
SO2
934
696
25%
NOx
264
264
0%
Cost per Life Saved of FGD
• Dahanu 500 MW plant has a seawater
FGD
• Raises cost of electricity by 9%
• Estimated removal efficiency = 80%
• Estimated 123 lives saved annually
• Cost per life saved = $3.55 million Rs.
• Cost of FGD would be higher using
conventional FGD
• But most plants have higher damages per ton SO2
Conclusions & Caveats
• Damages estimates are preliminary—need
to refine atmospheric chemistry
• Benefits of controlling SO2 are clear
– Whether require scrubbers or use a permit
market depends on differences in costs of
control across sources
– Differences in pollution damages per ton SO2
across plants small
• Significant health benefits of coal washing