Comments on the Proposed Increase in the Minimum Emission Standard (MES) for Sulphur Dioxide (SO2) Applicable to Coal-Fired Power Plant Stacks in South Africa

Dr. Ranajit (Ron) Sahu, acting as a consultant for the Centre for Environmental Rights, provides a technical critique of the South African Department of Environmental Affairs' (DEA) proposal to increase the Minimum Emission Standard (MES) for sulphur dioxide (SO2) from 500 mg/Nm3 to 1000 mg/Nm3 for coal-fired power plant stacks.

• The author argues that the proposal to double the SO2 MES limit to 1000 mg/Nm3 is based on false assumptions regarding water use, technology costs, and the environmental impacts of Dry Sorbent Injection (DSI).
• The claim that Flue Gas Desulfurization (FGD) technology consumes excessive water is misleading, as FGD water use is a small fraction of total consumptive water in thermal power plants, particularly those using water-based cooling cycles.
• Dry-FGD designs are presented as a viable alternative for water-stressed areas, capable of achieving the 85% reductions required for the 500 mg/Nm3 standard and potentially reaching limits as low as 200 mg/Nm3.
• DSI is criticized as an inappropriate primary SO2 reduction technology because it was originally developed to remove acid gases like hydrochloric acid (HCl) and hydrofluoric acid (HF), with SO2 reduction being only an ancillary benefit.
• Implementing DSI to achieve a 70% SO2 reduction would significantly increase Particulate Matter (PM) loading on electrostatic precipitators (ESPs), likely requiring expensive ESP upgrades and causing adverse impacts on ash handling systems.
• The use of DSI, particularly sodium-based sorbents, increases the risk of toxic metals such as arsenic and selenium leaching into groundwater from ash landfills.
• DSI may adversely affect mercury emissions by scavenging oxidizing agents, which prevents the formation of soluble oxidized mercury and increases the emission of elemental mercury into the atmosphere.
• The author contends that the government's cost analysis is flawed; while DSI has lower initial capital costs, its operating costs are sizeable, and the total levelized cost may not be significantly cheaper than FGD when ESP upgrades and landfill requirements are included.
• The author recommends that the 2020 stack MES for coal-fired plants in South Africa be reduced to approximately 200 mg/Nm3, aligning with global norms and achievable through FGD.

APA

Sahu, R. (. (n.d.). Comments on the Proposed Increase in the Minimum Emission Standard (MES) for Sulphur Dioxide (SO2) Applicable to Coal-Fired Power Plant Stacks in South Africa. Centre for Environmental Rights. https://cer.org.za/wp-content/uploads/2019/07/Annexure-4_-Ron-Sahu_Report_on_MES_Increase_July-2019.pdf?x21779

Chicago

Sahu, Ranajit (Ron). Comments on the Proposed Increase in the Minimum Emission Standard (MES) for Sulphur Dioxide (SO2) Applicable to Coal-Fired Power Plant Stacks in South Africa. Centre for Environmental Rights, n.d. https://cer.org.za/wp-content/uploads/2019/07/Annexure-4_-Ron-Sahu_Report_on_MES_Increase_July-2019.pdf?x21779.

Wikipedia

{{cite report |last1=Sahu |first1=Ranajit (Ron) |title=Comments on the Proposed Increase in the Minimum Emission Standard (MES) for Sulphur Dioxide (SO2) Applicable to Coal-Fired Power Plant Stacks in South Africa |publisher=Centre for Environmental Rights |url=https://cer.org.za/wp-content/uploads/2019/07/Annexure-4_-Ron-Sahu_Report_on_MES_Increase_July-2019.pdf?x21779 |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{sahundcomments, author = {Sahu, Ranajit (Ron)}, title = {{Comments on the Proposed Increase in the Minimum Emission Standard (MES) for Sulphur Dioxide (SO2) Applicable to Coal-Fired Power Plant Stacks in South Africa}}, institution = {Centre for Environmental Rights}, url = {https://cer.org.za/wp-content/uploads/2019/07/Annexure-4_-Ron-Sahu_Report_on_MES_Increase_July-2019.pdf?x21779}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }