Indian Power-plant NOx Emissions: OMI Satellite Retrievals vs Bottom-up Inventory Estimates (Preliminary Results)

David Streets and Zifeng Lu

Argonne National Laboratory

Argonne, IL 60439

AQAST Meeting EPA Research Triangle Park November 16-18, 2011

A new, multi-year, bottom-up inventory of NOx emissions from Indian power plants has been developed

A detailed, unit-level inventory has been developed for India’s power sector during

1997-2010

– All units with capacity larger than 20 MW (> 500 units) are included

– Plant-wise fuel consumption

Data source: Thermal Performance Review (1997-2010)

Central Electricity Authority, Ministry of Power, Government of India

NOx emission factors (g/kg)

NOx control assumptions

– Coal-fired power plants: Units built after 1996 are equipped with Low-NOx burners

(LNB)

– Other thermal power plants: India has NOx emission standards for gas-, liquid-, and

diesel-fired power plants

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<100 MW 100–300 MW > 300 MW

w/o LNB 6.55a 7.00a 8.57b

w/ LNB 3.78c 4.00d 5.01a,d

a Zhao et al., 2008 b IPCC, 2006 c Estimated d Zhao et al., 2010

Increasing trend in Indian NOx power plant emissions

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From 1996 to 2010, Indian thermal power plants showed: Generating capacity: 84% increase Electricity generation: 110% increase Coal consumption: 95% increase

NOx emissions: 71% increase

Indian power plants locations vs. NO2 columns

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Graphic shows the spatial distribution of

monthly mean tropospheric NO2 from

OMI during March 2005 – February 2011.

Data source: KNMI,

DOMINO ver. 2.0, Level 3

Seasonal response is highly variable

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Due to frequent cloud cover and heavy

monsoon rainfall, July to September is the

worst period for India to observe NO2 from

satellites.

Interannual variation of “power-plant” NO2 columns

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Indian power plants are aggregated

to 81 areas • 0.625⁰×0.625⁰ for an area with a single plant

For area i, NO2 tropospheric column

due to emissions from power plant is

calculated by:

[NO2]power, i = (Emipower, i ÷ Emii)× [NO2]i

• Emii are total NOx emissions in area i

• Area emissions are taken from EDGAR4.1

for 2005, and scaled to 1997-2010 based on

the GAINS inventory

Satellite NO2 trends for power plants are in good agreement with bottom-up NOx inventory emission trends except for 2010

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R: the correlation coefficient between each dataset and Indian NOx power-plant emissions Satellite data sources: OMI, KNMI, DOMINO ver. 2.0, Level 3 SCIAMACHY, KNMI, TM4NO2A ver. 2.0, Level 3 GOME-2, KNMI, TM4NO2A ver. 2.0, Level 3 GOME, KNMI, TM4NO2A ver. 2.0, Level 3 It is possible that more plants are equipped with LNB during Indian 11th Plan of Renovation and Modernization (R&M) and Life Extension Programme (LEP) from 2008 to 2012 (~25% capacity is involved).

Comparisons of NOx emissions vs. NO2 columns

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Scatter plots

R2 vs. the fraction of power emissions in the grid cell (Fpower)

Situation for India seems better than for China

Similarity

NOx emissions from power sector are high and are

continuously increasing in both countries

Differences

The latitude of India is lower than China. Therefore, in

India,

– temperature is higher; NO2 lifetime is shorter;

observed NO2 columns are more closely correlated

with NOx emissions

– solar zenith angle is smaller, and thus the

tropospheric NO2 retrievals are more reliable (the

vertical profile sensitivity of the satellite

measurement is a function of solar zenith angle at

the time of satellite overpass)

– seasonality is weaker. All-year data can be used,

whereas only summer data are used for China

Area emissions are smaller in India than in China

– Indian NO2 columns are distributed as individual

hotspots which are good for quantitative analysis

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