Eskom recently began load-shedding again after it was able to avoid doing so during January, stating that there is a shortage of capacity and a need to replenish and preserve emergency water and diesel resources.
Eskom announced stage 2 load-shedding on Sunday and Monday, following weeks of consistent power supply.
Eskom spokesperson Khulu Phasiwe said the reason the utility was able to avoid load-shedding up until now was thanks to two factors.
Firstly, Eskom performed maintenance on its power systems during the festive season and started to see performance improvements as a result.
Secondly, Eskom has been burning diesel to make up the shortfall in generation capacity.
“It’s not a good thing, but we have been using diesel to make sure we keep the lights on,” Phasiwe told MyBroadband.
“Diesel is far more expensive than all the other [energy] sources we use, but when the system is under constraint we do use diesel to make sure we avoid load-shedding.”
Phasiwe noted that compared to the cost of load-shedding on the South African economy, burning diesel is the better deal.
Energy expert Chris Yelland estimated in 2015 that the cost to the economy during stage 1 load-shedding is R20 billion per month, using an average of 10 hours of blackouts per day for 20 days a month.
Stage 2 load-shedding, using the same time parameters, costs the economy R40 billion per month, while stage 3 is estimated to cost R80 billion per month.
The Department of Public Enterprises used the same figures in a presentation to parliament.
Phasiwe said that if these estimates are correct, you would rather spend R1 billion a month to burn diesel than have the country lose R20 billion to load-shedding.
“It is not ideal, I have to concede, but [using diesel] is something we have in our arsenal for fighting load-shedding and, from time-to-time, yes we do use it,” said Phasiwe.
As a result, Eskom was able to mitigate the risk of load-shedding in January.
According to Eskom, its two conventional hydroelectric power stations and two hydro pumped storage schemes, which are used when there is a sudden peak in demand, have a combined installed capacity of 2,000MW.
Similarly, Eskom’s four quick reaction gas turbine power stations have an installed capacity of 2,426MW. Two of these are “older generation” open cycle gas turbine stations (OCGTs) which use kerosene, whereas the two newer ones run on diesel.
Stage 2 – a cause for concern
What is of concern, however, is that the recent load-shedding has revealed how precarious the capacity situation at Eskom really is.
Despite bringing a number of generating units back online, when Eskom had to “replenish and preserve” emergency water and diesel resources, it had to go straight to stage 2 – shedding 2,000MW of load.
Without Eskom’s expensive diesel generators and other “emergency” facilities, South Africa would be in dire straits.
Of further concern is that despite Eskom’s intention of performing load-shedding on Sunday to avoid having to do so in the week or, stage 2 load-shedding continued on Monday.
“Although a number of generating units have returned to service as per the 9-point recovery plan, regrettably additional units continue to trip. This results in a shortage of generating capacity,” Eskom said.