South Africa’s Eskom, already named as the world’s biggest sulphur dioxide (SO₂) emitter, is seeking approval to release more of the pollutant linked to ailments ranging from asthma to heart attacks.

The move is part of an attempt by the company to reduce the level of temporary blackouts the nation is facing as a result of its inability to meet demand.

Eskom has asked South Africa’s environmental affairs department to allow it to bypass the flue-gas desulphurisation (FGD) unit, which removes the toxic gas (known by its chemical symbol SO₂) from emissions at three of the six units at Kusile, the biggest coal-fired power plant in the world outside of Asia.

By doing so, Eskom could return the units to operation a year earlier than if it first connected them to the FGD by building temporary structures while repairs continue to a duct that collapsed in March 2022.

That, in turn, would allow the state-owned utility to restore 2 100 MW of generating capacity to the grid at a time South Africa is suffering from a crippling energy shortage.

Rotational blackouts occurred on more than 200 days in 2022 as Eskom’s plants repeatedly broke down, and varying levels of outages have been imposed every day so far in 2023. President Cyril Ramaphosa last week declared a state of disaster to enable the government to accelerate its response to the energy crisis.

“The temporary stack solution will bypass the FGD and there will be an increase in the total mass of SO₂ emissions from the stacks compared to the case where FGD was operating,” Eskom said in a response to queries. “The environmental impact of these increased emissions is yet to be determined.”

Kusile, one of Eskom’s two newest plants, is the only coal-fired one out of the 14 it operates to use the technology, which costs billions of dollars to install

By temporarily bypassing the pollution abatement unit, Eskom will increase emissions of SO₂ eightfold, to 80 000 t at Kusile alone, said Lauri Myllivirta, lead analyst at the Centre for Research on Energy and Clean Air. Finland-based CREA said in a 2021 study that Eskom was the world’s biggest emitter of SO_2.

“The pollutant is responsible for the brunt of the public health impacts caused by the company’s emissions,” Myllivirta said in response to a query. If Eskom’s request is granted, it “would further add to the toll on public health associated with Eskom’s coal power emissions, which already stands at over 2 000 deaths a year,” she said.

Eskom disputes that figure, which has been cited in at least two studies, saying 320 deaths a year can be attributed to its emissions.

The utility supplies almost all of South Africa’s electricity, with more than 80% of national supply coming from coal-fired plants. In addition to SO2, the company produces about 40% of the greenhouse-gas emissions in South Africa, which is the world’s thirteenth biggest source of the climate-warming emissions.