FGD units are specially designed equipment installed in coal-fired thermal power plants to contain sulfur dioxide (SO₂) a harmful pollutant from the smokestacks.
For removing SO₂, they use techniques like wet scrubbing with limestone slurry. With this method the final out put would be “gypsum”, which is widely used in construction field.
Is FGD Unit Really Necessary in Coal based Power Plant ?
A committee led by Principal Scientific Adviser Ajay Sood has recently recommended to get rid of FGD unit for most of the Thermal Power Plants in India. Committee clearly stated that decade ago guidelines for installing FGD Unit is not useful for reducing SO₂ emission, moreover it is boosting the emission of CO₂.
Their analysis included data from CSIR‑NEERI, IIT Delhi, and NIAS, which found current ambient SO₂ levels (10–20 µg/m³) are well below the national safe limit of 80 µg/m³
Main reason behind the low SO₂ levels in the smokestack is only because of the sulfur content in Indian coal. If you compare Sulphur content in Indian coal with other countries it is typically low i.e. 0.3–0.5%, which makes FGD less impactful on air quality.
So the committee has recommended to throw away the old policy of continuing FGD units in most of the Thermal Power Plants [ TPP] .
Another main reason is CO₂ emissions would increase if FGD’s are installed in power plants. Here is the math, this clearly explains the drawback of installing FGD unit i.e. for reducing 17 million tonnes of SO₂ emission, we are making 69 million tonnes of extra CO₂ emissions.
Committee suggested to install FGD units in Power Plants with comes on Category A :
Based on the insights they got from research team, committee suggested tiered implementation
Mandatory for plants near large urban or polluted areas : Category A
Power plants with in 10 km radius of major cities are recommended to install FGD units.
Case-by-case review for moderately critical zones : Category B
Full exemption for the remaining Power plants : Category C
When does Government issued a Mandate for installing FGDs ?
In 2015, the government mandated FGDs for thermal power plants, with deadlines between 2018 and 2022, later they have extended it to 2024 and beyond.
In the year 2025 , based on the expert committee’s decision, installing FGD is not mandatory atleast in Class B & Class C category power plants.
Another interesting factor is, thorugh the government has given mandate to install FGD units, due to some unfavourable conditions like Covid, High installation cost and lack of skilled labout, by 2024 in only 8% of the 600-plus coal units , FGD units are installed.
About Public Health & Pollution :
The panel notes that particulate matter (PM) is a far larger health threat than SO₂ in India. It recommends focusing on Electrostatic Precipitators (ESPs) to limit PM, as they’re more cost-effective and beneficial