Thava Govender, the divisional executive responsible for power generation at Eskom, recently took members of the South African National Energy Association (SANEA) behind the scenes when he gave a presentation on Eskom’s generation plant performance and maintenance during SANEA’s ”Action for Energy” workshop in Johannesburg.
According to Govender, Eskom is currently managing a tight power system, which will continue for the next five and especially the next two years, while they expand their capacity. “Eskom kept the lights on from 2008 through to winter 2011, thanks to a lower than expected demand and initiatives put in place to manage the tight system,” he said. Unfortunately this does not mean that Eskom is in the clear. “Summer is maintenance season, and with our maintenance backlog we are running a tight schedule to meet the demands. This means that we run the risk of not fully meeting increasing electricity demands as units need to be taken out of service for essential maintenance.”
He gave an overview of Eskom’s struggle to make ends meet, explaining that the organisation came a long way from load-shedding that made headlines in 2007/2008 to successfully providing enough electricity for the Soccer World Cup in 2010. Govender added that although Eskom upholds international standards in performance, this is not always good enough when considering South Africa’s growing demands for electricity. “Our plant performance is still in line with international benchmark standards, but it is deteriorating. We have implemented performance recovery initiatives, but sustaining superior performance levels gets more challenging. Deteriorating plant conditions increase the scope of the maintenance outage.”
Peaking at the wrong time
Govender says that as the global economy started to recover in 2010, so too did the national peak and energy demand grow to the equivalent of the 2007 levels.
“Several of Eskom’s stations are also currently in their midlife and this means that significant refurbishment work is needed. This coincides with a high increase in demand that Eskom has to meet and puts us in a tight spot.”
He says the maintenance schedule Eskom compiles is based on peak electricity demand projections. What makes the situation even worse is that maintenance was kept to a minimum in 2010 to ensure sufficient capacity during the World Cup tournament. “The overall electricity supply system remained healthy during the month-long tournament despite South Africa experiencing the coldest winter in 20 years.”
Govender explains that in 2010 the system was also run much closer to the “red line” compared to 2009 in order to address plant maintenance requirements. “The total amount of maintenance work done was still insufficient and hence a maintenance backlog has developed.”
A fine balancing act
This year the electricity demands of the country bring about another set of balls to be juggled. Govender stressed that the annual peak demand day that usually occurs in June or July happened on 31 May this year. He says the demand was forecasted to peak at 36 300 MW during the evening. “The total averaged over an hour peak was 37 065 MW. This was managed by using interruption of supply contracts.”
According to him, the demand on Eskom’s capacity was further reduced by using capacity from municipalities, resulting in a peak demand on Eskom of 36 543 MW. The instantaneous peak within the hour was approximately 300 MW higher. To help meet the demand, their open-cycle gas turbines were used to keep the lights on.
Govender says the residential usage of power takes up a significant chunk of the peak demand cake. “During the high seasonal period the tariff hike had no significant effect on power usage. The year-on-year growth in residential peak demand is 3,59% and the year-to-date energy growth is 2,71%. This growth can be attributed to a colder winter.”
He says that Eskom is resolved to keep the lights on, but they will be tested on this time and again and can’t do it alone. “Energy-efficiency is crucial to ensure there is enough capacity to meet the electricity demand and to provide the required reserve. This also includes the protection of the overall system, as well as to provide the opportunity to perform maintenance, inspections and refurbishments.”
Full acknowledgement and thanks are given to Eskom and SANEA for the information given to write this article.