eBusiness Weekly
Golden Sibanda
Zesa Holdings is working on upgrading Hwange Power Station to restore the plant’s generation potential to rated capacity of 920 megawatts from current levels of around 700MW, acting group chief executive officer Patrick Chivaura has said.
The life extension project for Hwange, to be funded under a US$310 million loan from India, will also improve the safety condition of the power station, which has postponed mandatory maintenance for four years due to serious financial limitations.
Chivaura said recently that there still was some hope remaining on the potential contribution of Hwange Power Station; which was completed in the mid to late 80s, although the plant had long outlived its design lifespan of about 25 years.
Hwange is critical to power supply in Zimbabwe given that, as the country’s major base load station, it provides most of the power requirements during peak and off peak periods.
Zimbabwe’s demand for power at peak periods stands at 1 600MW against generation capacity of about 1 500MW with the balance met through imports from the region. Kariba South, after a US$533 million extension, produces 1050MW.
However, Kariba as a peaking plant is not always available due to limitations around lake water levels, which sees authorities rationing water when levels are dropping fast.
This is the reason Government has enlisted Sinohydro, which did Kariba South extension, to expand Hwange by adding two more units of 2x300MW capacity at a cost of US$1,4 billion.
Hwange life extension
“We are engaged in a life extension project for this plant, the existing one. As we say, the rate capacity was 920 megawatts and at the moment we can just scratch under 700MW.
“So we do have a bit of headroom, which we would like to enjoy, so we are in a (life extension) project, which will be bankrolled by Indian funding of US$310 million.
“So it is a project we are focusing on so that we maximise what we get out of the existing plant. There still is good hope for the existing plant,” Chivaura pointed out.
The advanced age of the Hwange Power Station, Zimbabwe’s largest base load plant, has often presented operational challenges due to frequent break downs, leading to interruptions to power generation and supply.
Safety concerns
Station manager, Anold Chivurayise, told Energy and Power Development Minister Joram Gumbo recently that the deferred statutory maintenance programmes were now posing threats to the safety of employees who operate the machinery.
In fact, the National Social Security Authority (NSSA), a State regulator that enforces work place safety standards in the country, had to be lenient on the state power utility, and it to operate the major power plant without the statutory maintenance.
“But that also poses a challenge, when you defer a pressure part machine because it has safety implications to both personnel and the machines themselves.
“So there is need to avoid a situation where we cannot run the machines because they are no longer operable,” said Chivurayise, adding the plant needs comprehensive rehabilitation to restore proper safety conditions.
“NSSA have been understanding our situation and have allowed us to operate the boilers, but there shall come a time when they will say no, you cannot continue to operate some of the machines because of safety reasons,” he said.
Chivurayise indicated that most generators at Hwange Power Station were no longer producing to their optimum capacity. Unit 1 is generating 78MW, unit 2 110MW while unit 3 can produce an average of 85MW.
Deferred maintenance
However, generators 1 and 3 have had statutory and major overhauls deferred due to shortage of foreign currency, a situation that now poses some danger to workers who operate the machinery at Hwange based power plant.
“They were supposed to have had major overhauls four years ago because every five years we do a major overhaul and every 2 to 5 years we do what we call a statutory to inspect for safety reasons, since we deal with pressure parts, particularly the boilers,” Chivurayise said.
He said a major overhaul on generator 3 was postponed in January this year due to limitations of foreign currency because 90 percent of the required spares are imported.
Chivurayise said generator number 4 produces 90MW, but faces problems of generator grindings that hit up and is therefore also now in need of a major overhaul Unit 5 can do 150MW but is waiting for a statutory and major overhaul and was due for statutory maintenance in September last year, but it was deferred due to forex issues.
Chivurayise said unit 6 can produce upwards of 170MW, but beyond that “we face a problem of clinkering; the ash hardens on the tubes and they cause a problem. The problem is prevalent across all ancillary equipment.
For the ash plant, it has taken ZESA over a year to get spares. This is despite the fact that the order has been placed with the supplier, who insists on cash up front of US$500 000.
