Flue gas desulphurisation (FGD)

  • November 6, 2023
  • Posted by: OptimizeIAS Team
  • Category: DPN Topics
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Flue gas desulphurisation (FGD)

Subject :Environment

Section: Pollution

Context Coal-fired power plants in India are spewing sulphur dioxide into the atmosphere way above the allowed limit. The biggest culprits are those built after January 1, 2017, which are also wayward in putting out nitrous oxides, data from the Central Electricity Authority (CEA).

This brings into question the issue of installing ‘flue gas desulphurisation’ (FGD) in coal-fired plants, for which thermal power companies have managed to secure repeated extensions from the initial 2017 deadline.

Flue Gas Desulphurisation (FED):

  • Removal of Sulfur Dioxide is called as Flue-gas Desulphurization (FGD).
  • It seeks to remove gaseous pollutants viz. SO2 from exhaust flue gases generated in furnaces, boilers, and other industrial processes due to thermal processing, treatment, and combustion.
  • FGD systems may involve wet scrubbing or dry scrubbing.
  • In wet FGD systems, flue gases are brought in contact with an absorbent, which can be either a liquid or a slurry of solid material. The sulfur dioxide dissolves in or reacts with the absorbent and becomes trapped in it.
  • In dry FGD systems, the absorbent is dry pulverized lime or limestone; once absorption occurs, the solid particles are removed by means of baghouse filters.

Benefits of Flue Gas Desulphurisation (FED):

According to the Centre for Atmospheric Science, IIT Delhi, an FGD unit can remove anywhere between 50 and 99.8 per cent of SOx emissions, depending on the power plant’s vintage. CEA data shows that most of the plants with FGD have been able to keep SO2 emissions below the norm – only NTPC’s Dadri units 1, 3 and 4 – each of 210 MW capacity – are wayward.

Status

India has 2,07,045 MW of coal and lignite-fired power plants, of which only 22 units with a total capacity of 9,280 MW – less than 5 per cent – have been fitted with FGD

Sulfur Dioxide Pollution

  • According to a report by Greenpeace (an environmental Non-Governmental Organization), India is the largest emitter of Sulphur Dioxide (SO2) in the world
  • The primary reason for India’s high emission output is the expansion of coal-based electricity generation over the past decade.

Source:

  • The largest source of SO2 in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities.
  • Smaller sources of SO2 emissions include: industrial processes such as extracting metal from ore; natural sources such as volcanoes; and locomotives, ships and other vehicles and heavy equipment that burn fuel with a high sulfur content.

Impact: SO2 can affect both health and the environment.

  • Sulphur dioxide is bad for health and the environment.
  • Short-term exposures to SO2 can harm the human respiratory system and make breathing difficult. People with asthma, particularly children, are sensitive to these effects of SO2.
  • SO2 emissions that lead to high concentrations of SO2 in the air generally also lead to the formation of other sulfur oxides (SOx). SOx can react with other compounds in the atmosphere to form small particles. These particles contribute to particulate matter (PM) pollution.
  • Small particles may penetrate deeply into the lungs and in sufficient quantities can contribute to health problems.
  • At high concentrations, SO2 can harm trees by damaging foliage and stunting growth. When the gas mixes with falling raindrops, we get a shower of sulphuric acid.

Regulation of Sulphur/ Flue Gas Desulphurisation (FED):

In December 2015, the Ministry of Environment, Forest and Climate Change stipulated SO2 emission norms for coal-based power plants, compliance with which is possible only with the installation of FGD.

Phased Implementation

  • According to the Ministry of Power the implementation of the emission norms, requiring the installation ofFGD technology, got delayed due to various techno-economic constraints faced by thermal power plants and further affected by the impact of Covid -19 pandemic
  • The government initially decided on phased implementation of FGDs with maximum timelines up to December 2022 but later granted an extension of the time limit twice for implementation of the new emission norms for SO2 parameters up to December 2024, December 2025 and December 2026 for different categories of plants, based on their location.
  • In July 2022, the Centre for Atmospheric Science, IIT Delhi, recommended a “phased implementation” of FGDs across the country, the fifth phase ending in July 2034.

Central Electricity Authority

  • The Central Electricity Authority (CEA) is a statutory organization constituted under Section 3 (1) of the repealed Electricity (Supply) Act, 1948 and continued under Section 70 of the Electricity Act, 2003.
  • It was established as a part time body in 1951 and made a full time body in the year 1975. As per Section 70 (3) of the Electricity Act, 2003, the authority shall consist of not more than 14 members, including its chairperson of whom not more than eight shall be full time members to be appointed by the Central Government.
  • The CEA is headed by a chairperson who, as the Chief Executive of the authority, oversees largely the development of power sector in the country.
  • It advises the government on matters relating to the National Electricity Policy (NEP) and formulates short-term and perspective plans for the development of electricity systems.
  • It is the designated authority for cross border trade of electricity.
  • It also prescribes the standards on matters such as construction of electrical plants, electric lines and connectivity to the grid, safety and grid standards and installation and operation of meters.
  • It is also responsible for concurrence of hydro power development schemes of central, state and private sectors for efficient development of river and its tributaries for power generation.
Environment Flue gas desulphurisation (FGD)