While the winter period went well, with State-owned power utility Eskom avoiding having to implement load shedding, South Africa’s electricity supply would remain constrained over the coming summer months, State-owned power utility Eskom senior GM Andrew Etzinger said on Monday.

Speaking at an energy efficiency workshop hosted by the South African Property Owners Association, in Midrand, he pointed out that electricity consumption during the past winter was back at 2007 levels, partly as a result of slow economic growth, but also owing to the implementation of Eskom’s integrated demand management programme.

He added that a significant amount of maintenance had been completed during the winter, but that further maintenance was still planned for summer, which meant that the grid would remain under pressure.

“It is also important to note that while, in winter, the electricity demand peak is driven by residential users, in summer, it is driven by the commercial sector, which means that the daily constrained period lasts much longer,” Etizinger said, explaining that, in summer, the peak was spread across business hours.

He further stated that, to deal with this, the power utility had a number of resources that it could leverage through its demand response programmes.

“But the issue is that in summer it not as easy to use these resources on an ongoing basis. If we have industrial customers that agree to have their demand dropped for an hour or two when things get tight, that is good, but if the constraint reaches over ten hours, you need ten customers to each drop their demand for an hour to get the same effect. So it is a much tougher situation,” he said.

Eskom had also identified other demand/supply management options but these required funding, Etzinger noted.

“We have engaged our shareholders and the regulator intensively over the past few months and hopefully the funding will come through,” he added.

The residential mass rollout programme was a significant contributor to managing supply and demand and Eskom wanted to get started on the second phase of the project as soon as possible. Once the required funding was received, this would go forward, Etzinger said, adding that perhaps Eskom also needed a commercial rollout programme.

The extended summer peak period would also impact on how often and for how long Eskom would have to run its gas turbines, Etzinger said, adding that the turbines would be used to a large extent during the summer months.

Meanwhile, with regard to Eskom’s coal stockpiles, he stated that the power utility had about 52 days worth of coal available at its power stations.

“This stockpile would enable Eskom to keep producing power in the event of industrial action [at the coal mines] and it would also help us to mitigate against challenging weather conditions, as the coal at the bottom of the stockpiles will remain dry,” he said