EXPLAINED: This is why Eskom has doomed SA to new load-shed misery
Eskom’s mega power stations Medupi and Kusile, which were intended to alleviate SA’s power constraints, have a multitude of serious design and technical flaws that are impeding their operation.
The poor performance of the new stations is a key reason Eskom is still unable to meet the country’s energy demands despite adding 3,200MW of capacity to the grid since 2015. Eskom’s current installed capacity is about 38,000MW.
The utility went into stage-four load-shedding mode on Monday, dropping 4,000MW from the grid, the largest ever amount it has needed to shed to keep the grid stable.
Load-shedding takes place when demand exceeds supply and customers are dropped from the grid to avoid it tripping.
Eskom, which supplies more than 95% of SA’s electricity, says the main problems at Medupi and Kusile are the fault of the main contractor on the boilers, Japanese conglomerate Mitsubishi Hitachi Power Systems Africa (MHPSA).
It is not the first time that Hitachi’s work on Medupi has been found to be defective. In 2013, 10,000 welding faults were discovered when Hitachi failed to heat-treat the welds. In 2015, it failed the crucial steam test, a necessary step before commissioning.
In 2015 Hitachi and Mitsubishi Heavy Industries merged their power activities to form Mitsubishi Hitachi Power Systems Africa.
Hitachi’s award to build the boilers has always been controversial due to its partnership with the ANC’s investment company, Chancellor House.
In 2015 it was fined by the US Securities Exchange Commission for allegedly paying the ANC front a $1m success fee and $5m in “dividends” in connection with the Medupi and Kusile contracts.
A multiplicity of faults have been identified as common to both Medupi and Kusile. In its updated tariff application to the National Energy Regulator of SA (Nersa), Eskom lists seven technical and design problems.
These include: the boiler design results in high temperatures that the spray water system cannot adequately cool, leading to frequent tripping; the design causes excessive ash accumulation, and ash bags must be frequently replaced. This causes ash blockages, frequent tripping and load losses. None of the coal mills, which pulverise the coal going into the burner, meet technical specifications, with the consequence that they must be serviced twice as frequently as normal.
The gas air heaters, which capture waste heat and transfer it to combustion air, enhancing the efficiency of the boiler, do not meet technical requirements. The dust handling plant, which is vital for safety, environmental and occupational health reasons, requires more frequent maintenance due to high ash accumulation, leaks and the scarce availability of spare parts.
The distributed control system – the computerised control system – frequently fails, causing plant trips, and does not meet technical requirements. Lastly, there is a high number of vibrations on the cooling loop.
Several of these problems are adversely affected by poor coal quality, states the Eskom presentation.
The presentation also lists a shortage of skilled people and unavailability of spare parts as an eighth factor negatively affecting Medupi and Kusile.
The result of the problems has meant that Medupi’s unit 6 (the first of three so far commissioned) has barely reached 60% of its capacity since June 2018. The remaining two units perform at about 70% capacity.
In response to questions last week, Eskom chief operating officer Jan Oberholzer laid most of the problems at the door of MHPSA, which he said were being managed through the terms of the contract.
Eskom has assembled teams of specialists to rectify the major defects, and technical workstreams have been established with contractors.
“Eskom will attempt to resolve issues in term of the contracts and may institute legal proceedings only should contractual resolution not be possible … It is Eskom’s position that the contractor will fix and pay for the faults,” he said.
MHPSA spokesperson Nicolas Meyer said the company did not wish to comment...