Eskom grid study highlights major future shifts in power-flow patterns

The transmission unit of South African electricity utility Eskom has completed a strategic grid study for the period to 2040. The study signals major shifts in future generation and demand patterns that will have implications for the domestic network and future investment decisions.

Strategic grid planning senior manager Ronald Marais says the ‘2040 Transmission Network Study’ has drawn on various scenarios to determine the grid’s development requirements, as well as to identify critical power corridors and network constraints.

The 2010 Integrated Resource Plan (IRP) provides the base case, but the draft IRP Update, together with scenarios that envisage higher levels of renewable energy (a ‘green’ scenario) and regional imports, have also been interrogated.

All show marginal implications for the transmission network for the coming 10 to 15 years. However, from 2030 onwards, major changes are expected in the provincial distribution of generation, with Mpumalanga – the current dominant source of generation – playing a relatively smaller future role.

“There is going to be a significant change in pattern,” Marais reports, adding that the ‘greater Cape area’ will become a major exporter of electricity.

Generation from the sun-drenched Northern Cape, for instance, is set to expand under all scenarios, and could be a major contributor by 2040, depending on the generation mix pursued. Likewise the wind-rich regions of the Western Cape and Eastern Cape are poised to become more significant sources of electricity supply.

Marais indicates that these shifts have implications for the direction of electricity flows, which are currently primarily from east to west, owing to the dominance of coal-fired generation in the north-eastern provinces and the dearth of generation in most other territories.

Under the ‘green’ scenario, the Northern Cape could have has much as 7 100 MW of surplus capacity by 2040, with the IRP base case suggesting a net generation surplus of nearly 2 000 MW. Similarly, the Western Cape and Eastern Cape could move from being net importers of electricity to net exporters through a combination of additional wind and new nuclear capacity.

Mpumalanga, meanwhile, which currently has a net surplus of over 22 000 MW, could see its contribution to the rest of the country decline to around 9 700 MW by 2040 as mature coal-fired stations are retired and South Africa moves to diversify its power mix.

Under all scenarios, the coal-rich Limpopo province’s power generation contribution is anticipated to grow materially, while Gauteng, KwaZulu-Natal and Free State are forecast to remain net importers.

The analysis identifies five major national corridors for future strategic development, including the western and eastern coastal corridors, a solar corridor, a central corridor and a northern import corridor, through which capacity from Mozambique, and potentially the Democratic Republic of Congo, would enter.

The direction of electricity transport will be much more varied when compared with the current patterns, with south-to-north and west-to-east flows anticipated. In addition, Eskom is planning to match generation centres to load centres using the shortest routes possible, so as to reduce the environmental footprint of the network, the investment costs and technical losses associated with moving electricity over long distances.

Marais reports that the national power corridors have been further refined and consolidated into five transmission power corridors, which are being used by the Department of Environmental Affairs for a strategic environmental assessment (SEA).

The SEA forms part of the Presidential Infrastructure Coordinating Commission’s strategic infrastructure project 10, or SIP 10, and the aim is to fast-track all the environmental approvals required for transmission infrastructure within the corridors.

Marais says corridors of 100 km in width have been identified and that the SEA will seek to identify environmentally acceptable routes over which long-term environmental impact assessment (EIA) approvals can be secured.

This is seen as important as EIA determinations, along with servitude acquisitions, are currently major impedi
ments to the rapid deployment of grid infrastructure. On average it is taking Eskom between six and eight years to secure the servitudes and EIA records of decision and a further three years, thereafter, to construct the lines.

Marais says that, while the shifts in power flows fall outside of Eskom’s current grid-planning horizon, as outlined in the Transmission Development Plan (TDP) for 2015 to 2024, the modelling is assisting with project prioritisation.

More immediately, however, the TDP is being heavily influenced by the utility’s financial constraints, which has led to the deferment of certain projects.

The overall budget, which was estimated at R163-billion, remained more or less as it was in previous versions of the TDP, with R146-billion required for capacity expansions and the balance split between refurbishments, spares, servitude acquisitions and environmental and corporate costs.

However, the latest version also rescheduled much of the actual investment into the fourth multiyear price determination period, or MYPD4. This is partly attributed to the fact that Eskom has received lower-than-requested tariff increases from National Energy Regulator of South Africa for the MYPD3 period from 2013 to 2018, but it also takes account of delays associated with securing land, servitudes and environmental approvals.

The rephrased plan envisages the building of 13 396 km of new transmission lines and the introduction of 81 385 MVA of additional transformation capacity by 2024.