Atmospheric emissions and pollution from the coal-fired thermal power plants in India
Journal article in Atmospheric Environment (2014) Download along with a 3:30 minute video explaining the key messages from the study
Update: August, 2013
A note from the Press Information Bureau of India, discussing this study report in the Rajya Sabha (Indian Parliament), leading up to formation of a standing committee to address the emission and environment standards for the coal-fired power plants. Download the press release.
Update: March, 2013
India's electricity generation is dependent on coal and will remain so for the coming decades. However, there is an immediate need to address the air emission standards for the coal-fired thermal power plants - for regional clean air and cleaner electricity production. An interview in New York Times.
Update: January, 2013
In India, the supply of electricity lags behind the demand from a growing population and economy. Despite that, India is the 4th largest consumer of electricity in the world. According to the Central Electricity Authority (CEA), in 2010-11, of the 122 GW peak demand for electricity, only 110 GW was supplied – which amounted to a shortfall of about 10%. A third of the population that lives in rural India does not have access to electricity. Even those with access in urban India have to deal with frequent power cuts and load shedding.
The power sector in India is currently dealing with two competing priorities – (a) demand for power outstrips supply (b) power generation using coal is polluting (given the low quality coal in use with high ash content and low calorific value) and hazards associated with the air pollution are a serious concern
At approximately 210 GW, India has the 5th largest electricity generation sector in the world (captive power plants generate about 31 GW more) with planned additional capacity of 76GW in the 12th five year plan (2012-2017) and 93GW for the 13th five year plan. The figure to the right presents the spatial spread and cluster intensity of the coal-fired power plants in India, operational in 2011-12. Thermal power plants account for 66% of generation, hydro for 19% and the remaining 15% from other sources including natural gas and nuclear energy.
Coal-fired power comes with significant costs to environment and human health. The water runoff from coal washeries carries pollution loads of heavy metals that contaminate ground water, rivers, and lakes - thus affecting aquatic flora and fauna. Fly-ash residue and pollutants settle on soil contaminating areas and are especially harmful to agricultural activities. Most importantly for human health, combustion of coal releases emissions of sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), volatile organic compounds (VOCs), and various trace metals like mercury, into the air through stacks that can disperse this pollution over large areas. Chronic and acute exposure to these pollutants has health impacts that include respiratory illnesses, compromised immune systems, cardiovascular conditions, and premature death.
Emissions and Dispersion of Particulate Pollution from Coal-fired Power Plants in India
We used the list of thermal power plants documented by CEA (http://www.cea.nic.in) as a starting point for building our database of operational coal-fired power plants in the country. We updated this database for 2011-12 representing a total generation capacity of 121GW. We also include in the database, geographical location in latitude and longitude, number of boiler units and size of all known power plants operated by both public and private entities. This data was gathered from websites and annual reports of the state electricity boards for public and private sectors. The public sector entities include - National Thermal Power Corporation; Indraprastha Power Generation Company; Haryana Power Generation Corporation; Punjab State Power Corporation; Rajasthan Rajya Vidyut Utpadan Nigam; Uttar Pradesh Rajya Vidyut Utpadan Nigam; Gujarat State Electricity Corporation; Madhya Pradesh Power Generation Company; Chhattisgarh State Power Generation Company; Maharashtra State Electricity Board; Andhra Pradesh Power Generation Corporation; Karnataka Power Corporation; Tamil Nadu Electricity Board; The West Bengal Power Development Corporation; Orissa Power Generation Corporation; and Calcutta Electric Supply Corporation. The private sector entities include – Jindal Power; CPL India; Azure India; Adani Power; Reliance Power; and Tata Power.
We utilized the ENVIRON - Comprehensive Air Quality Model with Extensions (CAMx) version 5.40, an Eulerian photochemical dispersion model, suitable for integrated assessments of gaseous and particulate air pollution over many scales ranging from sub-urban to continental. This model unifies all the necessary technical features of a "state-of-the-science" air quality model into a single open-source system that is computationally efficient, easy to use, and publicly available (http://www.camx.com). The movement of the emissions emitted from all the power plants, for the month of November, as a daily PM10 average, is presented in the figure to the right (click on the image for an enlarged view).
Animations for all the months are accessible here. A summary of the daily averages over each month is presented in the figure below (click on the image for an enlarged view).
The meteorological data for the dispersion modeling is derived from the National Center for Environmental Prediction (NCEP) global reanalysis and processed through the RAMS version 6.0 meteorological model. Visit http://www.urbanemissions.info/india-meteorology for animations of surface wind speed and direction, precipitation, and mixing heights for year 2010 at 2 hour interval.
Health Impacts of Emissions from Coal-fired Power Plants
The global burden of disease (GBD) assessment for 1990-2010 quantified the trends of more than 200 causes of deaths and listed outdoor air pollution among the top 10 causes of deaths for India. For India, total premature mortality due to outdoor particulate matter (PM) pollution is estimated at 627,000. This GBD assessment utilized a combination of ground measurements (where available) from the cities and substituted the remaining urban and rural area with data retrieved from satellite measurements for PM2.5 pollution. PM2.5 refers to PM less than 2.5mm in aerodynamic diameter.
In 2011-12, the emissions from coal-fired power plants, resulted in an estimated 80,000 to 115,000 premature deaths and more than 20.0 million asthma cases from exposure to total particulate pollution, which cost the public and the government an estimated 16,000 to 23,000 crores of Rupees (USD 3.2 to 4.6 billion). The largest impact of these emissions is felt over the states of Delhi, Haryana, Maharashtra, Madhya Pradesh, Chhattisgarh, Indo-Gangetic plain, and most of central-east India.
The health impacts are calculated using the concentration dose-response functions.
Key Messages from the Study
Besides the emissions from the stack, the fugitive dust from coal-handling units and ash ponds (after the disposal from the plants) needs special attention, given the expected increase in the coal-fired power plants.
The forward trajectory analysis, using 3-dimensional meteorology, of the emissions released at the stacks show that the impacts can be observed farther than 50-100km from the source region, which increases not only the ambient concentrations at these receptor points, but also increases the morbidity and mortality risk. Additional impacts include deposition of heavy metals and sulphur oxides on agriculture through dry and wet deposition. The environmental impact assessments necessary for commissioning the power plants, should include long-range transport to account for these impacts. The movement of the elevated emissions is illustrated using meteorology of two days in the figure below for four clusters (a) Korba cluster (in-land) (b) Jhajjar cluster (in-land) (c) Mundra cluster (coastal) and (d) Mumbai cluster (coastal). The forward trajectories are drawn for 24 hours, with a puff released at 300m height every hour and tracking its movement through the next 48 hours. The lines represent only the movement of the puffs in the horizontal direction and do not include any information on the vertical mixing or the pollutant concentrations. The release height of 300m is assumed, considering the large power plants in these clusters are mandated to have stacks of minimum 275m and allowing 25m for additional minimum plume rise (click on the animations for an enlarged view).
|These are trajectories for select days in the region.|
The forward trajectories are constructed using the HYSPLIT trajectory model by NOAA.
The secondary contributions from sulphur dioxide and nitrogen oxides emissions to the total fine particulate matter (with aerodynamic size less than 2.5 micron) varies from 30-60% of those observed over Madhya Pradesh, Chhattisgarh, and most of the central-east India. This is primarily due to lack of flue gas desulfurization units for most of the power plants in India. A mandate to implement this for new and all existing power plants will have an immediate relief to not only the ambient particulate pollution and related health impacts, but also a reduction in deposition of these gases over the rich agricultural lands.
To date, the pollution standards exist for ambient air quality only and not for individual power plants, which compromises the monitoring and enforcement efforts. Only after standards are set and regulations mandated at the plant level, can we proceed to the next steps of monitoring and enforcing policy, so as to have lesser environment and health impacts due to coal fired power plants. For particulate matter emissions, the emission standard in India lags to those implemented in China, Australia, the United States, and the European Union. For other key pollutants like sulphur dioxide, nitrogen oxides, and mercury, there are no prescribed emission standards. There is also no open and continuous emission monitoring data available at the plant level. This makes the enforcement of what standards do exist, nearly non-existent.
The way forward is for the coal-fired power plants is (a) to revise the emission standards for particulates and introduce new emission standards for other pollutants (b) introduce continuous monitoring at the plant stacks, such that the data is in the public domain in real time and (c) enforce the standards with improved impact assessment methods with human health as the primary indicator.
We would like to thank the Conservation Action Trust (Mumbai, India) for their support towards this research.
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