The latest data from Eskom shows that the utility went to great lengths to keep load shedding at bay between 20 and 28 October – despite generation and plant performance deteriorating.
According to independent energy analyst, Pieter Jordaan, Eskom effectively pulled the proverbial rabbit out of a hat by ramping up its usage of open-cycle gas turbines (OCGTs), aided by significantly lower demand.
This trick proved too much to keep going, however, after colder weather in the country at the start of this week saw demand spike, necessitating the move back to a stage 2 and stage 3 load shedding rotation.
The 43rd week of the year marked the longest streak of no load shedding seen in 2023. As previously reported, the week presented a “landing” to the near-permanent load shedding that “launched” in September 2022.
However, data from Eskom shows that load shedding remained suspended for nine days despite a drop in the group’s energy availability factor (EAF), and a significant escalation in unplanned outages (breakdowns).
Typically under these conditions, load shedding would be in effect and possibly escalating; however, the country enjoyed over 200 hours with no outages in sight. This means that something else was going on.
According to Jordaan, the one of the biggest factors is demand. Over the week, the country’s demand profile dropped significantly – to the lowest point this year.
The drop in demand is being driven by wider adoption of alternative energy sources (such as self-generation, rooftop solar etc) by individuals and companies alike. Demand is also falling as higher electricity tariffs in April and July are filtering through to consumption behaviour, the analyst noted.
The bigger trick to keeping load shedding at bay during the week, though, is burning diesel – and a lot of it.
According to Jordaan, while Eskom’s use of OCGTs has been on a downward trajectory since September, the annualised rate of utilisation was pulled upward sharply last week.
“Due to the high cost of OCGT generation, an annual utilisation rate of 1% is regarded as the utility-scale standard. In light of the South African power crisis, (energy regulator) NERSA made a concession to allow for a higher utilisation rate of 6%,” the analyst noted.
By mid-September the annual Eskom OCGT utilisation rate stood at 20%, but this started dropping to around 17% in October. Following the load shedding suspension, the annualised rate pulled up to 17.7%
“Diminished power demand reduced the use of OCGT for several weeks but due to excessive plant breakdowns (in week 43), a weekly utilisation rate of 31.3% has caused the annual utilisation rate to climb once more.”
In Eskom’s fifth multi-year price determination (MYPD5), the regulator, NERSA, capped output from Eskom’s Open Cycle Gas Turbines (OCGT) at 1,266 GWh or R8.4 billion for the current financial year, 2023/24.
For the current financial year to date, Eskom has produced 2,181 gigawatt hours of energy from OCGT at a NERSA estimate cost of R14.5 billion.
In its latest financial reporting, Eskom noted a staggering jump in spending on the group’s gas turbines in the current financial year, with total spending to be more than double the R14.7 billion spent in 2022, hitting R29.7 billion in 2023.