Editorial Comment: National effort needed to fix power supply

05 Dec, 2022 - 00:12 0 Views
Editorial Comment: National effort needed to fix power supply

The Herald

Electricity underpins our economic growth, is critical for our mining and industrial expansion, is needed to pump water for irrigation, and is the critical indicator at residential level of whether a family has reached middle-income or upper middle-income status.

And Zimbabwe does not have enough. Yet. So we have to press forward as a united nation until we do, both in the present short-term emergency caused by low levels in Lake Kariba and then to build up supplies as rapidly as possible in the medium-term and longer-term.

President Mnangagwa moved rapidly last week when it became apparent that Zimbabwe had used up its share of the stored capacity at Lake Kariba, and drastically widened the emergency response from the closed shop of Zesa and the Energy and Power Development Ministry to include all ministries and units that could do something helpful and useful.

Results are already seen. The Zambezi River Authority backtracked from its original wish to see Kariba South shut down to limiting output to an average of 300MW. 

That seems reasonable when you consider that the two power stations at Kariba never need to be switched off as some preach, since the Zambezi is a major perennial river. 

What goes over the Victoria Falls today can go through the power stations by the end of the week. But we are at the low water flow right now so what we get through the stations when we are using them as run-of-river stations is not much, probably around 300MW each. But at least we have that.

The world’s largest capacity man-made reservoir was designed and built to catch the annual floods when the runoff from south-east Angola and north-west Zambia, and this is where almost all the water comes from, reached the lake and then spread out the outflows through the power stations to get a regular flow, less than the flood flows, but a lot better than the low flows. 

But over the past four years we have seen two droughts, one under-flow season and one reasonable season. So storage has never been that great.

While Zimbabwe and Zambia extended their Kariba power stations last decade to 1 080MW on the north bank and 1 050MW on the south bank, that was to give Zesa and Zesco flexibility to meet peak demand, but make up for that by turning off most generators at say 1am. 

Unfortunately both utilities are over reliant on Kariba, partly because the power is so cheap now the dam wall is paid for.

The second step taken last week was to push Zimbabwe’s installed thermal capacity at Hwange Thermal and three old small thermals in Harare, Bulawayo and Munyati. Hwange Thermal with four 120MW boiler-turbine-generator units commissioned in the early and middle 1980s and two 220MW units commissioned in the late 1980s is rated at 920MW. 

Unfortunately the critical maintenance, which after a couple of decades would start seeing some major replacement parts, was skimped in the economic turmoil of the first decade of this century. Repair work does allow a 400MW output when pushed at present, and Zesa have promised this while Kariba South is on run-of-river at low season, but it will require continual attention by the engineers and basically an all-out effort by Zesa to deliver. 

Another 45MW can come from the little thermals, again with repair teams on standby. President Mnangagwa in his Sunday Mail column brought up other factors to ensure delivery, such as making sure enough coal is mined and, for the three small thermals, is delivered. He was not interested in excuses.

We can also import, although imports will be tight since SADC as a whole is short. Zambia will shortly be load shedding as its share of the little water stored is run down and it too moves Kariba North to run of river. 

South Africa, the regional generation giant, is short during peak periods and quite a bit of the rest of the time, but because its generation is almost all thermal and nuclear can keep power stations running 24/7, so will have surplus in the low periods. 

We can buy then, and save our limited Kariba water to use in other hours. Mozambique has the giant Cahora Bassa Dam, which at least gets the daily outflow from the Kariba and Kafue stations so has better supplies than either. 

Cyclone Idai filled it up, so the legacy of strings of drought are a lot less severe. In the very near future we get Hwange Extension on grid. The two 300MW units 7 and 8 were delayed by Covid-19, but are on course. Unit 7 is complete and the boilers have been lit. 

But the engineers want to ensure that both the unit and the synchronisation of the unit on the grid are perfect, so when it shortly is feeding power to the grid there will be no sudden and expensive breakdowns. Unit 8 follows about three months later.

In the medium term, finance of US$310 million has been secured from India and with our own resources we can soon start the planned rehabilitation of the older six Hwange units, to add what amounts to another 500MW. 

The revamping of the six involves a lot more than repairs. Some parts need total replacement. 

The civil works and probably some of the electrical works can be reused with modest repairs, but a lot of the mechanical equipment in the coal feed, the boilers and probably at least some turbines will probably need to be replaced. But at least this is now moved from the wish list to the planning stage.

President Mnangagwa is now generating ideas, and one is for many of us to take care of our own needs, in cities as well as the countryside where this is already part of the planning. 

He would like to see ever more houses with solar panels and solar water heaters on the roof, and wants housing finance to include this. 

Even the drive for far more flats can go this route so long as the architects ensure that the roof has the right pitch and adequate strength for a row of solar water heaters and a large block of panels.

He brought up the Muzarabani gas and oil exploration, which looks ever more hopeful. Gas will probably be more valuable than oil, not least because with an assured supply of gas a gas-fuelled power station can be built quickly. It is basically a jet engine driving a generator in a shed. It would make sense if the plans were drawn up now while exploration continues, along with answering such questions as to whether we have a long pipeline and short grid connection or short pipeline and long grid connection.

The President also brought up the fact that our secure energy resources are coal. We started discussing the next major coal station in the 1990s, and licences have even been granted to an independent producer to build it. Cows graze on the suggested sites. We need to move forward. 

Batoka may well need a rethink over cost effectiveness, since there is not much storage and if the final result is a quarter output away from the flood period then perhaps another site is required for the next major hydro.

Solar is gaining ground, and we have now signed a deal for a major 500MW plant, along with smaller commercial installations. But again we need more action. We are going to learn a lot in the next few weeks and months as we cope, but the biggest learning will be how to work together on energy, making sure we have enough.

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