Speaking at a quarterly state of the system briefing, during February 2014, in Johannesburg, South Africa, Eskom CEO Brian Dames said the lights are being kept on at a high cost. He said three power emergency declarations were raised this summer, the first in November 2013.
In each case, rotational load shedding was avoided due to the reductions in demand achieved by customers. He also said that South Africa’s electricity network will remain tight up to the end of summer of 2013/14 and throughout the winter of 2014, until the country’s new build programme delivers new capacity.
He said that as in 2013 maintenance will continue throughout the year and this could potentially increase the level of constraint. Government officials, Eskom and large customers continue to meet weekly to manage the situation and collaborate on solutions.
A number of events within the national diesel fuel industry in November 2013 and increased usage resulted in reduced diesel availability, adding pressure on the availability of emergency reserves. This resulted in the first system emergency being declared on 19 November 2013 and lifted on 21 November 2013. Dames describes this as a difficult but necessary decision, to avoid a total electricity system collapse.
He also says that increased emergency demand market participation and an energy buy-back of up to 1,000 MW were requested to supplement depleted emergency reserves. This was because supply levers such as the short-term independent power producer (IPP) program expired at the end of December 2013, creating further pressure for 2014.
In the week leading up to the 20th of February, there was an increase in unplanned outages and the imports from Cahora Bassa were reduced due to a conductor failure. This required the various emergency reserves and the pumped-storage schemes to be used extensively. A system emergency was declared for the evening peak of the 20th of February in line with the normal regulatory protocols due to possible risks that could have materialised.
“We saw nearly 1,000 MW of reductions from all the customers (industrial, commercial and residential). Eskom also secured up to 280 MW from those IPPs on the Short-Term Power Purchase Programme.”
The third emergency saw a system emergency declared for the evening peak of the 21st of February as the emergency reserves and dam levels were still at very low levels. The situation recovered over the weekend as imports were restored and six generation units returned to service.
Among the constraints that Eskom has faced during this summer is that the Duvha coal conveyor belt that transports coal from the adjacent mine to the power station was damaged in December 2013 – resulting in significant coal supply challenges for the station, requiring output reduction and additional open cycle gas turbine usage, thus limiting the opportunity for additional maintenance (short-term outages). Coal is temporarily being transported by trucks as a contingency.
In generation increased boiler tube leaks were the prime reason behind generator outages. Outage slips and extensions have taken much longer than initially planned due to the state of the plant when opened up for inspection as well as some performance issues in execution. Partial output reduction continued to be a challenge. Hot days impacted the ability of some power stations, particularly Matimba, to generate at full output. This design issue had up to 1,000 MW impact at Matimba alone.
During the day for January 2014, load was on average 500 MW higher than in 2013 due to the absence of energy buybacks in 2014 and the end of the short-term IPP programme. Despite the increased maintenance, this demand has been supplied though the extensive use of the OCGTs and increased levels of Demand Market Participation.
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