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

  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

(Lbs/MWh)

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 population-weighted ambient concentrations at each plant, based on gridded population data and precipitation data for India

!(

!( !(

!(

!(!(

!(!(

!(!(

!(

!(

!(

!(

!(

!(

!(

!(

!( !(

!( !(!(

!(

!(

!(!(

!(!(

!(

!(

!(!(

!(!(!(

!(

!(

!(

!( !(!(!(!(

!(

!(!( !(

!(

!(

!(!(!(!(!(

!(

!(

!(

!(!(!(

!(!(

!( !( !(!(

!(!(

!(

Population covered within 100km radius from power plants

Legend!( Coal based power plant

Population covered within 100km radius from the power plants

Population (2005)

Up to 10,00,000

10,00,001 - 25,00,000

25,00,001 - 50,00,000

50,00,001 - 75,00,000

More than 750000

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

         # obs Mean Std DevDeaths (All pollutants) 63 659 523Total deaths per plant due to      

PM 2.5 63 29 43SO2 63 499 407NOx 63 123 95

Deaths per ton of emission of      

PM 2.5 89 0.023 0.005SO2 89 0.010 0.002NOx 89 0.009 0.002

!(

!( !(

!(

!(!(

!(!(

!(!(

!(

!(

!(

!(

!(

!(

!(

!(

!( !(

!( !(!(

!(

!(

!(!(

!(!(

!(

!(

!(!(

!(!(!(

!(

!(

!(

!( !(!(!(!(

!(

!(!( !(

!(

!(

!(!(!(!(!(

!(

!(

!(

!(!(!(

!(!(

!( !( !(!(

!(!(

!(

Location of coal-based power plants

Legend!( Coal based power plant

Population (2005)Up to 10,00,000

10,00,001 - 25,00,000

25,00,001 - 50,00,000

50,00,001 - 75,00,000

More than 750000

Dahanu

Rihand

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

CoalWashed

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 1255 1001 20%Deaths due to      

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