Zimbabwe’s state-owned power utility, ZESA Holdings, has shortened power cuts this week as three generators at Hwange Thermal Plant kicked in, but the improved supply situation cannot be guaranteed moving into the future because the plant has become too unreliable, an official said.
“The stability can only be achieved when Units 7 & 8 at Hwange start generating power,” Energy and Power Development Minister, Zhemu Soda, told Business Weekly in an interview on Thursday.
The two new units, 7 & 8 combined, will add 600MW.
He said the current generators at Hwange “are too old to rely on as they can break down anytime” adding that the synchronisation of Unit 7 for it to come on board was “almost complete.”
Zesa chairman, Dr Sydney Gata, recently told local media that the giant thermal power plant was now surviving as a result of the “ingenuity of local engineers.”
The past two weeks have seen some of the worst power cuts with most consumers enduring prolonged periods of blackouts, sometimes lasting for 22 hours, in the process seriously affecting production at many firms that immediately resorted to alternative power sources.
In less than a week, from February 15 this year, four generators were taken off after developing problems. The other unit was switched off in October last year and during the better part of this year, the plant was running with only one generator.
According to a general supply summary by the ZPC, Unit 4 was switched off on 15 February after developing a boiler tube leak. Unit 1 was taken off on 24 February after a high-pressure fan got damaged. Unit 3 was stopped on February 24 after developing a tube leak while Unit 6 was switched off on February 23 after developing a similar problem. Unit 5 tripped in October 2021 due to excessive turbine vibrations. From the breakdowns, it’s clear that the plant can no longer be managed.
Explaining why ZESA missed its own deadline to start unit 7, Minister Soda said the commissioning of the new units “is too complex.” “A lot of processes are involved; these include testing the performance compliance levels at various production levels.
“You need to understand the behaviour of the plant; say when it is producing 100 MW, 200MW. So even when we switch them on, we still have to do all those processes and when that is done, we can then start producing at a commercial scale,” he said.
Minister Soda said the commissioning of the plant was also delayed due to challenges related to mobilising technicians from China following the resurgence of Covid-19 late last year.
Sino Hydro, the company contracted to build 7 & 8 had subcontracted ABB to conduct testing of the protection system but their technicians failed to travel to Zimbabwe on time.
When they eventually arrived, it took time for the technicians to understand the system. They also needed to be reinforced by a team from South Africa.
“But they have now assured us; they gave us the promise that before the end of this month, the synchronisation process would have been complete,” Minister Soda added.
The Hwange Power Station comprises six existing coal-fired units including four 120 MW units commissioned between 1983 and 1986 and two 220MW units commissioned in 1987. All the units have outlived their life spans by at least eight years.
He said ZESA has secured a US$310 million facility from India to rebuild Hwange plant.