The dirty business of apartheid-era dinosaurs: Inside an Eskom coal-fired power plant
The state-owned power utility is in a terrible state. And nobody can deny that, with its unwieldy debt levels and archaic power stations well beyond their service years, Eskom faces insurmountable challenges. We take you into one of them to see how Eskom produces power and why we’ll be stuck with load shedding for some time.
Coal. It was formed in the past, over millennia, under the heat and pressure of burial. The vast, ubiquitous opencast pits and mines that scar the Mpumalanga landscape yield millions of tonnes of the black combustible sedimentary rock that powers South Africa.
For years, it has been – and still is – creating jobs from mines to power plants. This commodity, and the pits and mines from which it is extracted, is, however, fast gaining recognition by the world as the graveyard of future generations.
Closer to home, Eskom’s coal-fired power plants, which overwhelmingly dominate baseload power generation, are dinosaurs built to power the apartheid economy and not a modern, diversified South African one.
They have been, and to some extent still are, arenas of grand corruption and nefarious motives not in line with the utility’s core business.
It is a dirty business, made ever more dirty by actors with motives in conflict with climate imperatives and basic environmental standards. As reported by Reuters, smog from burning coal is laced with chemicals such as sulphur and nitrogen oxides, mercury and lead as well as with radioactive elements such as uranium and thorium.
The same report also noted that “5,000 South Africans die annually in the nation’s coal belt because the government has failed to fully enforce its own air quality standards”.
Pollution and global warming are not the only risks Eskom poses to South Africans. The national bane of load shedding also finds its origin in much of the corruption that has characterised Eskom’s governance over the past 14 years. Its website explains that load shedding “is a controlled process that responds to unplanned events in order to protect the electricity power system from a total blackout”.
“While we generally use the word ‘blackout’ loosely to mean ‘no lights’ in our local area, a countrywide blackout has much more serious consequences.
“Blackouts occur when there is too much electricity demand and too little supply, bringing the power system into an imbalance and consequently tripping the system in its entirety.
“In South Africa,” Eskom explains, “we have to rely on ourselves to start the system from scratch – energising one power plant at a time and one section of the country at a time.
“In the event of a blackout… it could take up to two weeks to restore full power, which would have a severe impact on our country! This is why we use load shedding to manage our power system and protect it from such an event.”
So how did we get here and what is to be done? DM168 went on a fact-finding mission to get a glimpse of the past, present and future of Eskom.
Komati Power Station general manager Marcus Nemadodzi took DM168 on a tour of the station. It is one of the oldest remaining coal-fired power stations in South Africa and is next in line for decommissioning. It is also the site of a pilot project that offers a glimpse into how Eskom and the government intend to use the infrastructure left behind when the last unit’s turbine finishes its final rotation.
At its most basic, a power station is a converter of energy. The combustion of fuel – coal in this case – is a chemical energy conversion process that generates heat. This heat, in turn, converts water into steam at a very high temperature and pressure.
The heat or thermal energy in the steam drives the turbine, converting heat energy into mechanical energy.
Coupled to the turbine shaft is a generator. The kinetic energy of these often massive spinning turbines is transformed in the generator into electrical energy, which is synchronised with the grid. The end result is you, the end-user, being able to use electricity to power your life.
What the process looks like
It all starts with a coal mine, much like the one just outside of the small town of Ogies.
Transferred to the power station by truck or conveyor belt, the black stuff sits in a pile mandated to be a certain size to ensure there is always enough coal to burn. It is at this point, however, that many of the issues begin. Whether it’s broken conveyor belts or angry coal truck drivers, breaking the link between the site of extraction and the power plant can lead to losses in generating capacity and, subsequently, load shedding.
Eskom explains that conveyor systems are used to transport the coal from a nearby mine to a coal stockyard and then to the power station site. The purpose of the stockyard is to ensure there are sufficient coal reserves to keep the power station in operation if the mine encounters production problems.
From the coal yards, the coal is moved on another conveyor to a mill that pulverises it into a finer consistency that is more easily burnt for fuel. At Komati Power Station there are three dusty, noisy coal mills dedicated to each unit.
The pulverised coal is fed into a boiler furnace. Inside this giant furnace, hot air is blown through the pulverised coal to ignite it and create a consistent heat.
A power station with a single operating unit such as Komati may go through thousands of tonnes of coal a day.
This pales in comparison with a plant such as Lethabo, which burns 50,000 tonnes of coal, enough to fill 1,500 trucks each carrying 33 tonnes, every day. Boiler tubes are the hundreds of water-carrying metal pipes inside the boiler that, when heated, create the steam that drives turbines.
Boiler tubes are notoriously problematic, even in the newer plants such as Medupi and Kusile.
Nemadodzi, the station manager, says the tubes are positioned close to one another and that, if there is a leak in one, superheated steam threatens to cut into the lines of other tubes, causing a chain reaction.
For this reason, boiler tube leaks are taken seriously by Eskom’s operators, who often have to shut down a unit to allow the turbine’s generator rotor to stop spinning. This cools things down enough so that technicians are able to repair the damage.
Maintenance of this kind can add to Eskom’s capacity woes, leading to the load shedding we experienced this week.
A News24 article says the myriad technical problems that contributed to the escalation of load shedding to Stage 4 included “a massive explosion, a fire, boiler tubes rupturing due to age and poor coal quality, and an earth leakage”. Eskom chief executive André de Ruyter confirmed in a media briefing on 9 November that the power utility had recorded breakdowns at Lethabo, Matimba, Kendal, Medupi, Duvha and Tutuka power stations.
News24 notes that “these breakdowns are part of the larger problem Eskom is facing with the reliability of its ageing stations”.
“Unplanned breakdowns have, since mid-2017, increased dramatically. In the 2020/21 financial year, roughly a quarter of Eskom’s generation capacity was lost to unplanned breakdowns.”
It is the job of operators in a power plant’s control room to monitor that everything is running smoothly. Data-logging computers continuously monitor the main operating alarm systems, and provide a constant flow of information on video screens and printouts. Ideally, there should be no red lights flashing. As DM168 saw during our visit, there is a gulf between the ideal and reality.
The mechanical issues related to the age of the coal-fired fleet are compounded by years of neglect and deferred maintenance.
The cost of keeping the power plants running in the red for all these years is being paid with the hundreds of jobs and businesses lost directly and indirectly due to load shedding.
Ideally, you should not see any steam in these pictures, but the students studying by candlelight and the businesses haemorrhaging cash on fuel for their generators know there is nothing ideal about Eskom in its current state.
The machinery in an Eskom power plant is built to specification, with millimetres often meaning the difference between a unit working or it having to be taken out of service for maintenance.
Nemadodzi explains this by pointing out the warped surfaces of the turbines in the other units.
A piece of metal, spinning at 3,000 revolutions per minute, that protrudes by just a few centimetres, has the potential to spray bits of metal all over a turbine hall at a speed that could cause widespread destruction, adding to the utility’s woes.
This is one of the reasons Eskom has had to shut down units to do planned maintenance.
Rhulani Mathebula, Eskom’s acting group executive for generation, noted in a recent media briefing that every power station in the fleet was running with a “partial load loss”, which means every power station has at least one generation unit operating with faults that require attention.
That is why, in the absence of new generating capacity, there is, will be and has to be load shedding.
The average age of an Eskom power plant is 37, putting most of them within normal “retirement age”, when without any maintenance, they would break down. Deferred maintenance and poor management have added to Eskom’s bag of woes. DM168/OBP
This story first appeared in our weekly Daily Maverick 168 newspaper which is available for R25 at Pick n Pay, Exclusive Books and airport bookstores. For your nearest stockist, please click here.