A plume of thick grey smoke hangs over the Kendal power station, situated 40 km west of Witbank in Mpumalanga. (And about 110 km east of Johannesburg.) A report by Greenpeace released in October found that the Mpumalanga province has the highest levels of air pollution in the world, topping nitrogen dioxide levels across six continents. Greenpeace says the biggest sources of air pollution in the province are coal mines, transport and Eskom’s coal-fired power stations. Kendal is one of them. Thousands of tons of ash is being released into the atmosphere because the ash handling system and electrostatic precipitators at the Kendal power station have been broken down for months. The Daily Vox explains.
Let’s start with the broken down ash handling system
The main problem at the Kendal power station is that particulate emissions – technical jargon for ash made up of a poisonous blend of solid and liquid particles – are being emitted into the atmosphere. This ash is supposed to be contained from the atmosphere using ash handling systems. This problem has persisted for years but reached an “appalling” state earlier this year when the ash handling system broke down, according to energy analyst and managing director at EE Publishers Chris Yelland.
“I’m not sure whether this was because of inadequate design of the system or because the coal they are burning exceeds Eskom’s specifications and has very high ash content, overloading the system,” Yelland said in an interview with The Daily Vox.
How is the ash usually contained?
Fly ash is the name given to the ash that is emitted, Yelland explains. There are different methods of reducing the fly ash content – technical jargon for the tiny dark flecks by the burning of powdered coal carried into the air – of the gas that goes up the chimney.
Eskom uses a combination of two techniques to extract the ash. The first is called an electrostatic precipitator. This is an electrical system which removes the ash particles from the gas using high-voltage electrostatic charge and collecting the particles on charged plates. “It basically sucks out or attracts the fly ash from the gas,” Yelland said.
The other technique is to use a fabric filter. Also known as a baghouse, this technique allows the gas to pass through thousands of bags made out of fabric trapping the fly ash particles. Every now and again these bags of ash have to be emptied. Yelland says, of the two, the fabric filters are a more effective and modern technique for extracting fly ash.
The ash is then transported to an ash dump site nearby, stacked in layers and then covered with topsoil and regressed.
“When these things break down the ash that would otherwise be collected and be handled by the ash handling system goes up the chimney and you can see it in plumes of smoke. On a winters day this doesn’t go precipitate into the atmosphere, it just hangs there: like an eerie cloud,” Yelland said.
Basically it means our air is heavily polluted, not just in Mpumalanga but the pollution spreads to Gauteng too. “It has been reported before that the Witbank area has the world’s dirtiest air, and now this analysis of high tech satellite data has revealed that the Mpumalanga province is the global number one hotspot for NO2 emissions. This confirms that South Africa has the most polluting cluster of coal-fired power stations in the world which is both disturbing and very scary,” said Melita Steele, senior climate and energy campaign manager for Greenpeace Africa.
There’s a reason there are measures to prevent the fly ash from being released into the atmosphere. As a byproduct of coal, fly ash is packed with heavy metals and toxins. “These particles mix with water particles in the air to form very dangerous chemicals,” Yelland said. These chemicals then then precipitate into clouds and result in things like acid rain, acid mine drainage, and all kinds of horrible pollutants, he said.
And these pollutants are very damaging to human life.
To put it simply, air pollution is awful for the respiratory and cardiovascular health. It can cause illness and death. According to a 2017 report by the Centre of Environmental Rights, about 2000 South Africans die prematurely each year as a result of air pollution caused by the burning of coal in power stations.
Fly ash particles can become lodged in the deepest part of your lungs, triggering asthma, inflammation, chronic bronchitis, and other immunological reactions. The particles can cause heart disease, cancer, respiratory diseases, and stroke. Respirable crystalline silica – dust particles the in coal ash – can become stuck in the lungs and cause silicosis or scarring of lung tissue. This often leads to disabling and sometimes fatal lung disease and cancer. The heavy metals in coal ash – like lead, arsenic and hexavalent chromium – and the radioactivity of some ashes may increase harm caused by inhalation.
There also effects linked to low birth weight and impaired cognitive development in children.
How Eskom is handling the problem
“Kendal power station is currently operating with very high emissions,” Eskom said in response to queries. South Africa’s electricity supply company acknowledged that the Kendal power station is experiencing problems with it’s ash handling plant and electrostatic precipitators.
“The power station has been working on repairing the plant for several months,” it said. Eskom made progress with repairs from April to May, but this was interrupted when workers went on strike in June and July. Due to the strike, there was a need for high load factors at Kendal to avoid load shedding (however there was some load shedding) and this caused further damage to the ash handling plant and electrostatic precipitators – and higher emissions.
Eskom said there are plans to resolve the problem and planned short term outages have taken place over the past two months to repair the plant and reduce emissions. “These activities, including planned longer outages as well as a heightened focus will continue until the high emissions are resolved,” Eskom said.
In meantime, we are breathing in toxic fumes.