Eskom’s Medupi, Kusile hobbled by design flaws
Utility blames Japan’s Mitsubishi Hitachi Power Systems Africa, main contractor for boilers
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 power stations is a decisive reason why Eskom is still unable to meet the country’s energy demands despite adding 3,200MW of capacity to the grid since 2015.
The utility went into stage four load-shedding mode on Monday, dropping 4,000MW from the grid, the largest amount to date that it has needed to shed to keep the grid stable. Loadshedding takes place when demand exceeds supply and customers are dropped from the grid to avoid it from tripping.
Two of the six generating units that failed on Monday, causing the jump to stage four, were at Medupi.
Eskom, which supplies more than 95% of SA’s electricity, said the main problems at Medupi and Kusile lay at the door of the main contractor for the boilers, Japanese conglomerate Mitsubishi Hitachi Power Systems Africa (MHPSA). It is not the first time that Hitachi’s work at Medupi has been found to be defective. In 2013, 10,000 welding faults were discovered when Hitachi failed to heattreat the welds. In 2015, it failed the crucial steam test, which is a necessary step before commissioning.
In 2015 Hitachi and Mitsubishi Heavy Industries merged their power activities to form 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, common to both Medupi and Kusile. In its updated tariff application to the National Energy Regulator of SA (Nersa), Eskom lists seven tech-
nical and design problems.
These include: the boiler design results in high temperatures, which the spray water system cannot adequately cool, leading to frequent tripping; and the design causes excessive ash accumulation and ash bags must be frequently replaced, which 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 usual.
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 reasons of safety, environmental and occupational health, needs more frequent maintenance due to high ash accumulation, leaks and the low 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, Eskom’s presentation to Nersa states.
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 — which was 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’s COO Jan Oberholzer laid most of the problems at the door of Hitachi Power Systems Africa, but added that these were being managed by applying the terms of the contract between the companies.
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 terms of the contracts and may institute legal proceedings only should contractual resolution not be possible ...” he said.
“It is Eskom’s position that the contractor will fix and pay for the faults.”
A spokesman for Hitachi Power Systems Africa, Nicolas Meyer, said the company did not want to comment.
In another blow to the plants, it was reported by EE Publishers on Monday that Clyde Bergemann Africa — a main contractor to Eskom for the ash-handling systems and a subcontractor to Hitachi Power Systems Africa — has filed for business rescue. Employees walked off the site at Medupi and Kusile after they were not paid for the month of January.