The key to successful grid expansion and transformation is State-owned power utility Eskom’s ability to rapidly respond to the new generation footprint. Therefore, the power utility should be able to expand the transmission grid as soon as new generation access is needed, says Eskom strategic grid planning senior manager Ronald Marais.
He notes that, while new generation capacity is key, the pressure to keep the lights on with the existing capacity of the grids has resulted in a decline in the performance of installed generation.
Marais explains that the current transmission grid is designed to transport the power generated in Mpumalanga’s large, centralised coal-generation pool to the dominant load centres across South Africa.
He notes that about 77% of the load is located in the north-eastern part of the country – in Gauteng, KwaZulu-Natal, Mpumalanga, the North West and Limpopo – while 23% of the load is in the south-western part of the country – in the Free State, the Western Cape, the Eastern Cape and the Northern Cape.
Marais adds that, while the capacity of the transmission grid is appropriately sized to deliver the current load demand, the future generation resources to generate electricity – irrespective of fuel preference, whether wind, solar, gas or nuclear, but with the exception of coal – are predominantly located in the Western Cape, the Eastern Cape and the Northern Cape.
“A significant amount of this generation will need to supply the dominant load centres in the north-eastern part of the country, which is a factor of three greater than the current load in the south-western region.
“This implies that the existing transmission grid is inadequate to integrate future generation. The existing transmission capacity will quickly be consumed and new networks will be required. “This is not a result of bad or inadequate grid planning, or because the new driver is not increasing load. Rather, it is [the result] of new locations for the future generation,” Marais says.
While the speed of implementing new power generation ranges between two and ten years, depending on the fuel type, renewables and gas are typically in the two- to five-year range.
Meanwhile, renewable power generation, although spread over a large area, individually occupies a relatively small spatial footprint. The transmission grid covers distances greater than 1 000 km and the environmental-impact-assessment approval, servitude acquisition and construction of long transmission lines are typically completed in eight to ten years.
Marais points out that there is, therefore, a disconnect between the implementation of large amounts of renewable generation and the transmission network required to connect it.
He explains that the implementation of renewable generation, irrespective of location, must be reduced to three to five years.
“This can only be achieved through strategic anticipation of the correct corridors,” he says.