Power generation slumps

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Africa Moyo
Acombination of wet coal and most units down at Hwange Thermal Power Station has resulted in a marked decline in electricity generation in Zimbabwe.

Power generation declined to 764MW last Friday and marginally recovered during the course of this week to hit 913MW yesterday.

The Zimbabwe Power Company (ZPC) – the electricity generation arm of Zesa Holdings – is understood to be renovating Unit 2 at Hwange, as it seeks to boost generation capacity, but that will add only 110MW to supply.

Hwange comprises four older units of 110MW each plus the two units in the second phase of 210MW each. Although this gives the station a rating of 860MW an inadequate cooling system means that even when it was able to go flat out it could produce little more than 700MW.

Lack of maintenance over the years has seen the maximum output decline further.

ZPC has been periodically overhauling its power generation units at Hwange, and focus is on Unit 2 at the moment, amid indications that the process will only be completed by May this year.

Hwange was commissioned between 1983 and 1987 and poor maintenance over the years has made it vulnerable to incessant breakdowns.

The three small thermal power stations at Harare, Munyati and Bulawayo have their latest generators commissioned in the 1950s before Kariba was built and are struggling to generate upwards of 25MW per day.

Sources at ZPC say a big problem at Hwange, which uses pulverised coal as its fuel, is the fact that the coal is wet, which makes it difficult to form the free-flowing powder the station needs.

The biggest singe problem was that the two large units in the second stage, which account for almost half the capacity, were shut down owing to water logging although Zesa spokesman Mr Fullard Gwasira said they were coming back into service.

ZPC acting managing director Mr John Chirikutsi could not be reached for comment as his mobile phone was unreachable.

Mr Gwasira said output had been pushed up at Kariba South to make up some of the deficit.

Statistics on ZPC’s website show that on February 23, the country was generating 764MW from all its plants, with a marked decline at Hwange, which was generating a measly 145MW, meaning a maximum of two units were working.

Kariba Hydro Station was churning out 596MW, Munyati (15MW), Bulawayo (8MW) and nothing from Harare.

On Wednesday this week, power output at Hwange had marginally increased to 148MW, before jumping to 227MW yesterday which meant two more units were running.

Overall output across the power generation plants in the country had also risen to 913MW yesterday, which is markedly lower than the current national electricity demand of 1 600MW.

Before ZPC started the Hwange Unit 2 refurbishments, average electricity generation has been 1 200MW.

This means load shedding could be employed to manage the gap between demand and output.

Already, there have been reports of load shedding in some parts of the country, particularly high density suburbs.

Zimbabwe Electricity Transmission and Distribution Company (ZETDC)’s transmission and distribution manager Engineer Howard Choga recently said Kariba is averaging 409MW per day due to “low dam water levels”.

Eng Choga said the average at Hwange is 365MW because of “frequent generator outages” while the three small thermal stations are reportedly dogged by coal shortages. NRZ usesd to shift the coal.

Harare and Bulawayo are also dogged by boiler challenges.

However, the power challenges could be overcome in the near future as the expansion of Kariba nears completion, although water availability would remain a problem.

Kariba is being expanded to add 300MW to the national grid. The total installed capacity at Kariba would rise to 1 050MW upon completion.

Currently, 98 percent of the works have been done and the project is already feeding an extra 150MW into the grid since December 24 last year.

Expectations are high that the other 150MW would be fed into the grid in the next few weeks, and all things being equal, the new plant would be commissioned by the national leadership on April 5 taking Kariba South up to 1050MW. However with no extra flow in the Zambezi this means that maximum output has to be balanced by low output in off-peak hours.

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