Eskom’s long winter

2014-05-11 15:00

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We are still 3?600MW short, which the Medupi power station should have been producing by now, according to a power expert

So far this year, on average, a quarter of the country’s power generation capacity is out of order – either for scheduled maintenance or due to “unplanned outages”.

In the year to date, an average of 10?341 megawatts have been offline – about a quarter of the system.

By May last year, this number was 9?745MW and in 2012 it was 8?974MW.

In 2012, Eskom began publishing two system update bulletins each week, on Mondays and Thursdays, giving relatively detailed information on power supply and demand.

City Press has combined the 240 bulletins so far to get a sense of how the situation has changed over time.

The apparently good news is that, despite the catastrophic wet coal incident at the Kendal power station in March and the subsequent “pressurisation incident” that took out a unit of the Duvha power station, “unplanned outages”– or breakdowns – are significantly lower this year.

According to power expert Chris Yelland from EE Publishers, it is possible that we are seeing results from Eskom’s “unprecedented” campaign of scheduled maintenance that started in summer last year.

“If there is more planned maintenance, you should see less unplanned outages,” he said.

But Yelland’s impression is that Eskom is not getting a handle on the problem of power plants breaking down.

Eskom’s own basic rule is that unplanned outages should total at most 10% (4?000MW) of capacity, while planned maintenance should also amount to at most 10%.

So far this year, unplanned outages are taking out on average 4?882MW and go up to 6?000MW often, most recently this Monday.

That is still much better than the average in the first five months last year, which was 5?800MW.

But unlike last year, the planned maintenance this year is more extensive than the power lost to breakdowns.

Last year, the planned outages averaged almost exactly the 4?000MW target before winter. This year, they average 5?500MW.

According to Yelland, the fact that unplanned outages still spike to 6?000MW is “a very bad sign”.

According to Eskom spokesperson Andrew Etzinger, the power utility’s maintenance campaign this summer has “gone well”.

The original plans had to be scaled back somewhat in March due to the unusually wet weather and the loss of generation that followed, he added.

The 10% rule about planned and unplanned outages is also seasonal, he said.

In winter, the planned maintenance should fall to about 5% (2?000MW) while going as high as 6?000MW in summer, as it has this year.

The far tighter system this year is the result of catching up on maintenance before winter forces Eskom to produce all it can.

But this still results in a lower reserve margin – the buffer before power emergencies and load shedding.

These margins reflect supply and demand at the peak periods in daily demand around the time people get home from work.

This year, it is on average 1?680MW, significantly less than the 2?400MW in extra power provided by two diesel-guzzling open-cycle gas turbine (OCGT) plants.

Eskom’s diesel bill is estimated to be about R10?billion this year.

Adding to the power utility’s problems this winter is the fact that it will not be able to eliminate demand to the same extent as last year.

The National Energy Regulator of SA (Nersa) has refused to allow Eskom to charge power users for the expense of its controversial buy-backs from smelters.

According to Yelland, Eskom is being “disingenuous” about this.

It could choose to spend the money used on the diesel generators elsewhere, including the buy-backs.

Nersa did not ban the mechanism for reducing demand, it only ruled Eskom cannot have the cost recouped through tariffs, he said.

Considering the OCGTs produce power at up to R4 per kilowatt-hour, and buy-backs probably cost no more than R2/kwh, buy-backs should be possible this winter as a “pure commercial decision”.

Yelland said: “At the bottom of it is the fact that we are 3?600MW short, which the Medupi power station should have been producing by now.”

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