27 November 2012

Zimbabwe: Zesa Should Manage Load-Shedding Better

Photo: Antony Kaminju/IRIN
File Photo:Business by candlelight in Harare as blackouts become order of the day.


Zesa seem determined to make Christmas miserable for many, pulling out generators totalling 235MW of capacity at a time for maintenance and repair and so plunging thousands more families into darkness with no amended schedule of when these extra power-cuts will occur.

The load-shedding schedule that Zesa has largely adhered to over much of this year, and which was forced on Zesa by its regulator, has proved a boon.

Available energy has been distributed far more fairly and everyone knows which mornings and which afternoons and evenings they will be without power, so they can make plans themselves.

Zesa is partly correct that the planned maintenance of Kariba South is better done in summer than in winter, with one of the six 125MW generators at a time down. But we notice that it is going to take 36 weeks to move through all six, so we will be in the midst of winter next year by the time that work is done. Excuses that the work was postponed to December when industry closes is just drivel; Industry will be closed for less time than maintenance on the first generator takes, let alone all six.

If Zesa had really wanted to miss the worst of the Zimbabwean winter then they should have started in September so they could have finished before May. At least during that period there is more than 12 hours of natural light a day. Compounding the shortages for most of December is the need to bring down a 110MW generator at Hwange -- starting on December 7 -- and finishing two days after Christmas. And there is no guarantee that this estimate will be met.

Kariba South maintenance is irritating, but routine, and any reasonably competent engineer can estimate accurately how long a turbine and generator unit needs to be down. The problems on the more complex boiler-turbine-generator units at Hwange are notoriously difficult to diagnose until the machinery is in pieces.

We hope the regulator will insist Zesa provides it with a properly amended load-shedding schedule that it can pass on to the public for this long period; it may be impossible to do all eight months, but at least we need one for December, while a Hwange unit is also down, one for the first quarter of next year when it is still fairly warm and one for the second quarter when it will be darker and colder. We suspect if one Hwange unit has to come down, and we believe it is the first that was renovated in the latest programme, then the rest will also need to come down in sequence, so even when our dark Christmas is still an unpleasant memory we will be shorter of power than we have come to expect in recent months.

Of course, all this should be totally unnecessary. Zesa, like most utilities, should have that extra 10 to 15 percent of generating capacity at the very least, and then plan proper maintenance for the lower demand months, which are usually the lighter and warmer parts of the year.

But despite some clever billing variations that Zesa has been allowed to implement, the utility has yet to add anything to its generating capacity for more than two decades. Almost a decade ago serious suggestions were made to harness Lupane coal-bed gas in a gas-generating plant. This, unlike new hydro-dams or new coal stations, would have been easy to implement. Gas power stations are easy and fast to build, with the civil works being not much more than a shed and the equipment coming almost off the shelf.

If Zesa had been serious, a decent geological investigation of potential gas flows at Lupane could have been done in a few months, and once there was an assured supply of methane the actual power station could have been built and commissioned in around a further six months. Going flat out the Lupane project could have gone from bare semi-desert veld to a few hundred megawatts in around 12 months, and there are enough Zimbabwean industrialists now burning thousands of litres of diesel a day in their own generators who would have been willing to pay a modest premium up-front for a cheaper but assured Zesa supply.

But for some reason Zesa still seems wedded to the long-term plan to add more capacity at Hwange and Kariba South. Both are required in any sensible plan because Zesa is already taking maximum energy from Kariba South, the extension allowing it to draw more at peak times while cutting back in off-peak hours. Hwange extension is then needed to fill the resulting deficiency in base load. The Hwange-Kariba extension scheme is thus reasonable, but will take years to implement and is still talk and plans, not concrete and generators.

Plans for a second large modern thermal plant have been mooted for over 25 years; but the Gokwe skylines are still unsullied by cooling towers. As a result of all these delays Zesa has been driving its existing two large power stations at maximum speed, deferring maintenance until now, when deferments are no longer possible; there has been no miracle giving it extra capacity so the damage is the same as if they had done the work on time, which would have meant that we would not have

Kariba South and Hwange simultaneously shedding units, and so making a bad deal twice as bad.

It is that wishful thinking that really rankles, and will rankle even more as many more will have to spend Christmas Day in darkness eating cold food.

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