How Eskom managed to tame load shedding

The incredible shift from Stage 6 load shedding to Stage 3, potentially even lower, was arguably always predictable.

Just weeks ago, the country was on edge, anticipating Stage 8 – or worse – load shedding during the winter months. This will likely not come to pass.

It is a stone-cold fact that Eskom’s coal generation fleet performs far better in winter than in summer.

Partial load losses reduce and the non-existence of the summer heat in Mpumalanga means the output from the plants is generally ahead of what would be experienced in the hotter months. Basically, fears of Stage 8 (or worse) are probably overblown. For now, at least.

Data from the Council for Scientific and Industrial Research (CSIR) over last seven years illustrates this brilliantly.

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As one can see, this was always on the cards, as Eskom’s load shedding schedule eased from a peak of Stage 6 just one week ago to a peak of Stage 3.

During daytime hours this week, there is no scheduled load shedding.

The reason for load shedding overnight until the end of the morning peak is due simply to the large differential between the daytime baseload demand and the peak. In winter, this is extreme, in summer the curve is far flatter.

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The difference between what was expected and what the current reality is comes from five sources:

• Wind generation has kicked in, given winter cold fronts heading into the Western and Eastern Cape. From Friday evening, wind generation has produced – relatively consistently – 2GW (or 2000MW) of power. This translated into the reprieves from load shedding over the past weekend.
  
• The outsize contribution of this wind power cannot be underestimated. With one Koeberg unit offline until September (originally June), the 2000MW of wind power in coastal regions equates to somewhere around 2200MW to 2400MW of power, because of the losses on high voltage lines from Mpumalanga (or further, such as Mozambique). This means that having such strong wind generation during a period in which 900MW is offline has a larger impact than ordinarily.
  
• Planned maintenance has been cut to below the bone. According to Eskom, only 2407MW is currently offline due to planned maintenance. Remove the 900MW (or 930MW) from the equation and you’re left with about 1500MW. That’s three coal units … nothing more. Given the constraints on Eskom’s maintenance budget going forward, this may be a realistic amount of maintenance that can be done in winter months. What must also be noted is that plants scheduled to be shut down are receiving little to no attention.
  
• Open cycle gas turbines (OCGTs) are being used – a lot. Current spend is estimated at about R3 billion a month, as per Eskom data. This is a small price to pay for the larger impact of higher impacts of load shedding across the economy. An analysis of the last seven days, however, reveals that Eskom has been relatively prudent when it comes to running the OCGTs. Due to the substantial contribution from wind, Eskom has barely used its diesel turbines since Thursday. In fact, between Friday morning and Monday, it had only used OCGTs during five out of 72 hours.
  
• Its final boost has come from the most unexpected quarter: breakdowns are lower than expected. At 16056MW as of yesterday afternoon, these are more realistically at 13900MW if one excludes the mess that is Kusile (Units 1, 2 and 3 – totalling 2160MW). This is roughly in line with the number on Sunday afternoon (at 3pm – 15846MW) and is, rather realistically, a tremendous achievement if one considers just how bad the level of breakdowns had previously reached (21000MW and above).

Currently, data for June – albeit a week in – points to a much-improved generation performance.

The energy availability factor (EAF), a measure of how much generation capacity is online, is above 60% – for the first time since August.

In fact, over the last year, its available generation capacity in the first week of June is higher than in all but two months.

Of course, in ‘better’ months the amount of unplanned breakdowns was lower than currently, but its planned maintenance was significantly higher.

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Return of Koeberg Unit 1

Much depends on Eskom’s ability to return Koeberg Unit 1 back to the grid (900MW) after the replacement of its three steam generator units, currently delayed by approximately three months.

This means dependable baseload power for the south-western part of the country, without the ±20% overhead of transmitting this over high voltage lines through the Free State and Karoo. Following this, it needs to take Unit 2 offline for the replacement of its steam generators. There is no room for error here with the application to extend the plant’s life for a further 20 years on the table.

Beyond this, the return of ±2000MW from Kusile’s units currently offline due to a duct failure will make a massive impact to the power system in December.

Originally, Eskom said these would be brought on stream with temporary flues from December onwards (into 2024). In its most recent presentation the 2300MW from the three units plus Unit 5 which still has to be commissioned is due to all come on stream in December.

A further 720MW will be connected to the grid from Medupi Unit 4 (which exploded in August 2021, shortly after the entire station was commissioned).

There is also some renewable capacity due to come on stream in the near term, as well as demand-side measures.

Things might not quite be as bad as we expected…

This article originally appeared on Moneyweb and was republished with permission.
Read the original article here.