Does a flue gas desulphurisation unit add CO2 at a coal power plant?
Yes, a little. Wet limestone scrubbers release the carbon in the limestone: 0.44 tonnes of CO2 per tonne of limestone, or about 0.69 tonnes per tonne of SO2 removed. It is small next to the coal, but it is a real process emission and should be reported, along with the scrubber's power use.
The chemistry
Limestone (calcium carbonate) reacts with SO2 and oxygen to make gypsum and releases CO2. Each 100 kg of carbonate gives 44 kg of CO2.
What to report
- Process CO2: tonnes of limestone used x purity x 0.44.
- Electricity for fans, pumps and mills inside the unit, already in auxiliary consumption.
- Gypsum sold to cement or board makers carries no share of the CO2.
Scale
For typical Indian coal with low sulphur, the scrubber adds well under 2 percent to the plant's CO2, but leaving it out understates Scope 1.
What Senseible does here
Senseible reads fuel, electricity and freight invoices into a dated, fingerprinted record per site, so each figure you send a buyer can be traced back to the documents behind it.
Sources: IPCC 2006 Guidelines, Volume 3 Industrial Processes, IPCC 2006 Guidelines, Volume 2 Energy (fuel defaults)
Last reviewed 2026-10-21.