Consider the following:

1. Carbon dioxide
2. Oxides of nitrogen
3. Oxides of Sulphur

Which of the above is/are the emissions/emissions from coal combustion at thermal power plants?

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

Explanation

Option (d) is correct

• Thermal Power Plants (TPP): Processes involved: fossil fuels such as coil, oil, and natural gas are burnt to produce heat
  • Heat is used to produce high-pressure steam from water
  • High-pressure steam is used to drive a steam turbine
  • A generator attached to the steam turbine generates electricity.
  • In India, most TPPs use coal as fuel (coal contains many toxic elements). Their energy efficiency is very low (20-45%).
  • Most TPPs do not employ pollution-reducing techniques such as flue gas desulphurisation (FGD), electrostatic precipitation, etc.
• Pollution:
  • Fly ash (electrostatic precipitator ash, dry fly ash, pond ash and mound ash) is a byproduct of coal combustion. It is discharged into the air and ash ponds (fly ash + water). The collapse of ash ponds contaminates nearby farms, homes, surface water bodies and groundwater with toxic heavy metals and other elements.
  • Toxic heavy metals in fly ash: Mercury, cadmium, arsenic, lithium, zinc, iron, copper, nickel, boron, magnesium, lead, aluminium, etc., are widely detected in the air as well as water bodies around TPPs.
  • Other toxic elements in fly ash: Fluoride, sulphur, etc.
  • Gaseous Pollutants from TPP: Carbon Dioxide (CO2), Sulphur Dioxide (SO2), Oxides of Nitrogen (NOx), Particulate Matter (PM), Methane (CH4), Carbon Monoxide (CO — from incomplete combustion), Volatile Organic Compounds (VOCs), etc.
  • Water Pollution: Heavy metal pollution due to acid mine drainage (AMD) from open-pit and underground coal mines and TPP effluents (cooling tower blow down, ash handling wastewater, wet FGD system discharges, etc.).

Answer: (d) 1, 2 and 3 | Difficulty Level: Easy