The emission standard for SO2 from coal-fired thermal power plants is acknowledged to be the most challenging to meet. Photo: iStock
The emission standard for SO2 from coal-fired thermal power plants is acknowledged to be the most challenging to meet. Photo: iStock

A central meeting showed pushback against tech in power plants to reduce SO2 emissions. Here’s why it’s a bad idea

New IIT-D study has challenged need for flue gas desulfuphisation in thermal power plants

Union Minister for Power and New and Renewable Energy (NRE) RK Singh recently presided over a high-profile meeting to review the results of a study conducted by IIT-Delhi on ambient atmospheric sulphur dioxide (SO2) concentrations and the effect of installing flue gas desulphurisation (FGD) technology on SO2 emissions in various categories of cities, as defined by them.

The meeting was attended by senior officials, including secretaries and joint secretaries from the Ministry of Power, chief engineers and deputy directors from Central Electricity Authority (CEA), a director and an additional secretary from the Ministry of Environment, Forest and Climate Change (MoEF&CC), a scientist from Central Pollution Control Board (CPCB), members and advisors from apex public policy think tank Niti Aayog and general managers and executive directors from NTPC Ltd.

The emission standard for SO2 from coal-fired thermal power plants (TPP) is acknowledged to be the most challenging to meet. This is largely because FGD, the technology to control sulphur levels in the exhaust emissions of power plants, is expensive and was, until recently, heavily reliant on imports.

In the last 8.5 years, the technical and financial complexities of FGD installation, as well as related regulatory issues, have been used as reasons to extend the deadlines for complying with the emission norms set by the MoEF&CC in 2015.

However, never before has the usefulness of this technology been questioned with such conviction. 

The timing of these “new findings” from a high-profile group is not surprising to those who have been following the trajectory of compliance by thermal power plants with the emission norms. Almost every time a deadline has approached, these government institutions have invariably managed to find some “compelling” reason to delay the implementation of the norms. 

With just a few months remaining for nearly 19 gigawatts (GW) of installed capacity to meet the SO2 standards by December 2024, the new study discussed at the meeting has significantly discredited the importance of FGD for TPPs in India.

An office memorandum detailing the minutes of the meeting was assessed by Delhi-based think tank Centre for Science and Environment (CSE). It states that the SO2 emissions from coal-fired TPP stacks have no significant impact on ambient air quality beyond a 60-kilometre radius from the power plant. 

It also disputes the significant formation of secondary particulate matter (both PM 2.5 and PM 10) from SO2 emissions from coal-fired TPPs. The study’s key findings, as recorded in the minutes of the meeting, are summarised in the following table:

Some findings of IIT-Delhi on ambient atmospheric SO2 concentration and impact of FGD installation in different category of industries


Category 1 cities

Category 2 cities

Category 3 cities

(without TPP)

(TPP without FGD)

(TPP with FGD)

SO2 concentration in ambient air due to TPP emissions

No effect 

No effect 

No significant difference observed in SO2 ambient air concentration despite FGD 

Secondary particulate matter (PM 2.5) from SO2 emissions

2 +- 2%

4 +- 1%

4 +- 2%

Secondary particulate matter (PM 10) from SO2 emissions

1 +- 1%

3 +- 1%

3 +- 1%

Source: Author’s compilation from office memorandum detailing the minutes of the meeting

In simple terms, the findings loosely suggest that the SO2 standards for power plants might not have been necessary to set in the first place. If it weren’t for the documented evidence, an observer of these meeting proceedings might mistakenly conclude that coal power plants are among the cleanest industries!

Instead of defending the standards it had established, the MoEF&CC noted that it might be “difficult” to “modify” the SO2 norms after eight years since their introduction.

Niti Aayog took a more progressive stance, albeit with a focus on promoting carbon capture from coal TPPs rather than other environmental issues. VK Saraswat, a member of Niti Aayog, stated that implementing a carbon capture and utilisation (CCU) plant would require the installation of FGD to reduce SO2 in the flue gas.

NTPC, which has awarded contracts for FGD installation covering 93 per cent of its operating capacity and has already installed the technology in three of its plants, opined that FGD operation in power plants could reduce import dependency for gypsum and sulphuric acid.

CEA) submitted that the cost of FGD has increased to Rs 1 crore per megawatt (MW), leading to an additional charge of 0.50 paise per unit of electricity if the technology is installed in power plants. It is worth noting that the cost of FGD has surged from Rs 35 lakh to Rs 1 crore per MW in the last eight years.

Although consumers would bear the additional costs if FGD is implemented, the coal power plants and regulators are seemingly absolved of any responsibility for the technology prices being subject to market forces.

While it has been shown that controlling SO2 from TPP might not have a significant impact on ambient air quality, concerns about increased water consumption and CO2 emissions from FGD operation were raised in the meeting.

The deliberations led to the issue of following action points: 

  • CEA is to conduct a cost-benefit analysis of FGD installation, assessing its impact on electricity tariffs, benefits from gypsum production and its impact on CO2 emissions.
  • CEA and NTPC will study and present to the Ministry of Power the cost-economics of a CCU system.
  • CEA will compile a list of imported items required for FGD manufacturing, with the aim of promoting domestic production of these components.

The latest office memorandum appears to be an attempt to justify scrapping SO2 standards or, at the very least, making them case-specific. In these 8.5 years, work orders for FGD installation have been awarded for a 100 GW capacity, 9 GW has installed FGD and manufacturing has advanced to the point where only 17 per cent of FGD components are imported.

This despicable attempt to ‘do away’ with SO2 norms altogether raises two pertinent questions. First, does it imply that MOEF&CC and CPCB applied zero consideration when setting the emission standards for coal power plants?

Second, if these organisations are at fault for establishing SO2 norms for power plants, who can say that the National Ambient Air Quality Standards, against which the new findings have been assessed, serve as a reliable benchmark for the mindfulness of these scientists?

Regarding regulatory and policy efforts, considerable resources have been spent on legal battles over deadline extensions, norm relaxations, petitions for tariff changes and regulatory processes aimed at simplifying implementation. 

Was all this in vain? This office memorandum threatens to undermine the systems set up over the past eight years to comply with the norms.

It is sad to observe the poor state of environmental governance in the country, said Nivit Kumar Yadav, programme director, industrial pollution and renewable energy unit at CSE. 

“It is difficult to understand how Minister of Power and NRE chaired a meeting about the feasibility of standard setting. It is also sad to find environmental regulators siting silently in meeting which is discussing implementation of standard which they had bought 8.5 years back. It’s time for MoEF&CC and CPCB to take a stand and prove their existence,” Yadav added. 

Down To Earth