Eskom interim CEO Calib Cassim has described unlocking grid connection capacity, using curtailment, as an urgent priority while Eskom and other stakeholders assess funding options to expand the transmission network.

Speaking at a climate conference in Johannesburg, Cassim reported that discussions were under way on how to ensure that more renewable-energy independent power producers (IPPs) were connected to the grid ahead of the large-scale grid-related investment that was being planned.

“While we are still going to take a number of years to expand the grid, we need to connect these megawatts.

“There may be a portion of the year when those renewables IPPs will be curtailed.

“Let’s manage that cost – it's a relatively small number – and not wait for a perfect solution,” he said at the event, which was jointly hosted by Standard Bank and SOAS University of London.

A recent assessment by Eskom and two European transmission system operators – 50Hertz of Germany and Elia of Belgium – showed that the capacity of the existing Western Cape grid to host variable renewable generators could be doubled under a scenario where no more than 10% curtailment was implemented.

Curtailment involves the active reduction of output from wind and solar plants in response to system security needs or temporary transmission capacity constraints and is widely used by system operators to facilitate the introduction of renewable generators in a context of grid constraints.

The analysis indicated that 4 GW of additional renewables capacity could be connected to the Western Cape grid “almost immediately” and that more than 90% of the electricity that these plants would produce could be safely integrated into the grid.

Curtailment of up to 10% also offered more economic value than new investments, primarily where wind technology is the source of the variable renewable electricity. It also showed that solar typically paired better with batteries than curtailment, because, unlike wind, all solar plants would generally be producing at the same time.

Both Eskom and the IPP Office have confirmed previously that they were assessing a new approach to curtailment to allow for additional generation capacity to be built at points on the grid that had previously been shown as fully committed.

Had such rules been in place ahead of the sixth bidding round of South Africa’s public renewables procurement programme, it would have been possible to contract for 3 200 MW of new wind projects in the Western, Eastern and Northern Cape. In the event, no wind projects advanced to preferred-bidder status, owing to claims by Eskom that the grid capacity on which the projects were premised had been absorbed.

It is understood that the curtailment framework could be released ahead of the next public procurement round, which was initially scheduled to proceed in September.

The framework could be unveiled once the updated Generation Connection Capacity Assessment is released; a document which is reportedly undergoing internal Eskom governance processes.

Meanwhile, Cassim also said that Eskom, which is currently being restructured into transmission, distribution, and generation entities, should be “open minded” about future funding options for the grid itself, which could include private sector participation. It is estimated that some R230-billion of investment will be needed by 2032 to add 14 000 km of transmission lines, as well as associated transformation capacity.

However, he stressed that there was also an urgent need for investment in distribution infrastructure and for a national conversation on the future structure of the sector, which is highly fragmented with many of the country’s more than 250 municipalities holding distribution licences.

“There are a number of smaller distributors and municipalities that are not investing and if you want to deal with the security or supply and access, we can't ignore that element of the value chain,” he concluded.