Eskom’s maintenance plan will take some time to yield results

5th June 2015

By: Terence Creamer

Creamer Media Editor

  

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When the Eskom board suspended four executives in March, Public Enterprises Minister Lynne Brown based her support for the move largely on what she perceived as a lack of “credible information” flowing from the managers on a range of issues, including plant instability and maintenance.

In the public imagination, this left the strong impression that the State-owned utility did not have an appropriate plan to arrest what had been a precipitous decline, since 2010, in the performance of its coal-fired power stations.

A range of justifiable questions immediately arose: Is there indeed a maintenance plan? If it does exist, does Eskom have the skills and resources to implement the programme? By when, if ever, is the situation likely to improve? Why doesn’t Eskom do higher levels of maintenance and raise certainty by conducting daily load-shedding on a predefined schedule? For how long will South Africans be expected to endure confidence-sapping and growth-threatening power cuts? Is there now a real danger of a total blackout?

At this stage, none of these questions can be answered with a high degree of certainty. But Eskom has started to offer some insight into the extent of the maintenance backlog, while also sharing some of the remedies it is pursuing.

Following an analysis of its generation assets, the utility has broken the performance of its 121 producing units into four colour-coded categories: good (green), not so good (yellow), bad (orange) and very bad (red).

In Eskom’s own assessment (it will be interesting to see if the Dentons-led inquiry finds differently), only 49 units are in the green, with the 72 others falling into the other far more worrying categories. Fourteen are considered to be in the yellow, while 26 are in a ‘bad’ condition and 32 in a ‘very bad’ state.

The net result is that the energy availability factor (EAF) across the fleet has fallen from 90% in 2001 – the year Eskom was voted the world’s best utility – to closer to 70%, with unplanned breakdowns having surged to around 15% last summer.

In other words, while Eskom has a theoretical dispatchable capacity of 43 500 MW (this figure excludes all renewable-energy projects, which cannot be dispatched, as output is based on natural phenomena such as the sun and wind), a combination of plant breakdowns, planned maintenance and partial load losses means it has been struggling to meet a daily demand peak of less than 30 000 MW. As a consequence, there were 12 consecutive days of load-shedding in April and, in May, the number of consecutive days of load-shedding materially breached 20.

But why has it deteriorated to this point? The internal analysis shows a strong, yet lagged, correlation between the current high level of plant breakdowns and delayed implementation of planned outages spanning all the way back to 2006. In fact, it shows that the maintenance underspending actually started in 1997, but that, from 2006 to 2014, the sum of the outage days delayed increased materially as the system became increasingly constrained.

What Is Being Done?
The focus of the maintenance plan is to arrest the unplanned losses in 2015/16, move to consolidate and stabilise the EAF in 2016/17 and accelerate those gains by materially changing the balance between proactive and reactive maintenance from 2017/18 onwards.

The three-year ‘turnaround programme’ has been facilitated primarily by a change in policy away from ‘keeping the lights on’ to operating and maintaining the generation assets to agreed ‘availabilities, capacities, reliabilities and efficiencies’.

It involves 14 project interventions, ranging from deploying maintenance engineers from head office to the actual power stations to improving outage planning and management.

However, the plan does not involve a major increase in the volume of planned maintenance, which has been increased from 7% to 10%, instead of the 15% level initially envisaged. This is because Eskom’s analysis indicates that it does not have the people, the parts and spares, the finances or the reserve margin to make such a step change.

Instead, the aspiration is to focus on the quality of the maintenance programme by improving planning processes and project execution. The theory is that, once Eskom has reduced the capacity lost, it will have more space available for proactive maintenance, which will trigger a virtuous circle and a shift in the balance in favour of proactive and preventive activities.

The immediate outlook, however, is not good. Eskom’s own statistical model shows that, for 2015, there is a probability of load-shedding for 25% of the days in a year, or for over 90 out of 365 days. The risk is lower in winter when planned maintenance tapers and the prospect of partial losses associated with high temperatures and wet coal falls.

Nevertheless, the threat of load-shedding in winter remains, as it does on any day when the gap between available capacity and demand shrinks to below 5 500 MW, including a 2 000 MW operating reserve.

When the gap falls below that level, Eskom has a protocol of deploying various resources to close it, with rotational load-shedding used as a last resort to sustain grid-system frequency at 50 Hz. It begins with the expensive diesel-fuelled open-cycle gas turbines and its peaking hydropower schemes, before pulling short-term supply and the demand-response levers it has contracted with the private sector.

Over the medium term, the gap should be bolstered through the injection of some new Eskom capacity, but primarily through non-Eskom supply- and demand-side management.

With the introduction of Medupi Unit 6 from July, followed by the Department of Energy peaker projects later in the year and the first unit of the Ingula pumped-storage scheme in early 2016, the dispatchable installed base should rise to over 45 000 MW. However, the system’s vulnerability to load-shedding is only expected to ease in the latter parts of next year and only if these capacity additions are supplemented with aggressive demand-response schemes.

Until then, the probability of load-shedding remains high but difficult to predict, owing to Eskom’s approach of only resorting to load-shedding as a last resort, rather than as a standard operating procedure.

Blackout Risk
Eskom is more confident, however, in its ability to prevent a catastrophic blackout, stressing that load-shedding is used deliberately to ensure that such a scenario does not materialise.

As is now well understood by all South Africans, Eskom has broken its load-shedding model into four stages, with the first stage involving 1 000 MW of cuts and the fourth stage 4 000 MW. During the fourth stage, only 81% of demand is being met by the utility.

But what would happen if even more than 4 000 MW of load-shedding is required? Eskom has a protocol known as ‘unscheduled load-shedding’, which would be deployed to sustain system frequency at 50 Hz and prevent an uncontrolled tripping of the network.

However, under even more extreme conditions, power stations could also be ‘islanded’ from the network to ensure that some capacity is sustained in order to restart the entire system over days. As a final safety net, the utility also ensures that diesel and dam reserves are never fully depleted so that these can be used as a ‘battery’ in the event that the system has to be restarted.

The utility is adamant that it has a plan in place to deal with a maintenance backlog that is result- ing in the poor performance of the coal fleet. But it is going to take time to yield results and it is also becoming increasingly clear that system stability is going to hinge increasingly on new non-Eskom generation and vastly upscaled demand-side management and response programmes.

Edited by Martin Zhuwakinyu
Creamer Media Senior Deputy Editor

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