South Africa

This is what it will take to keep South Africa’s struggling power company running

Outages are common and are estimated to cost the country’s economy around US$1 million per hour.

This article first appeared in The conversation.

The chief operating officer of South Africa’s power utility, Eskom, warned in May that the government should urgently start building new generation capacity. He was referring to a new building program that has been around for at least a decade.

The country 2019 Integrated Resource Plana cabinet-approved document sets timelines for dismantling coal-fired power plants and adding 44 GW of new capacity, including 18 GW of wind power and 8 GW of solar (photovoltaic) power.

The country is already way behind schedule, limping with antiquated power plants and regular blackouts. Breakdowns are a regular occurrence which are valued cost the country’s economy about $1 million an hour.

South Africans are only too aware of the existence of an energy crisis. But in my work on energy systems and transitions, I started asking questions about the real nature and extent of it, and how Eskom should respond to it. My opinions are informed by those of Eskom data portal, a rich source of information on South Africa’s complex power system. The portal is designed to share detailed information on electricity demand and supply. It has data on energy sources, storage levels and the magnitude of load shedding (power cuts) on an hourly basis.

I analyzed demand and supply data for the first half of May 2022. This revealed three main trends: demand has fallen; power outages are not as severe as they could be; and it is possible to get the most out of the system by using renewable energy sources.


The Data reveals three major trends for the public service. First, Eskom lost 6 GW (about 21%) of demand in one year. Indeed, many non-paying customers have been disconnected and several large customers, including industrial users such as mines, now produce their own electricity.

The figure below compares two days of demand, one in June 2021 and one in May 2022. It reflects actual demand, not Eskom’s supply. The difference in demand is staggering. At this rate, South Africa will simply not need Eskom in five years.

The second interesting finding is that the amount of power cuts is small compared to the total energy supplied. During the week of May 12-19, 2022, Eskom delivered 4,271 MWh of electricity and cut 70 MWh, which is only about 1.6% of the energy generated, as shown in the image below -below.

I make this point to show that the power cuts could get worse, unless the reconstruction program begins soon. One of the reasons why power cuts attract media attention is that consumers bear a disproportionate share of power cuts compared to Eskom’s main customers.

For example, at Level 4 where power outages can last more than five hours per day, lower end users only have electricity for 67% of the day, which means that 33% of their electricity supply is cut off. But the total energy saving on the whole system is 10%. This suggests that Eskom is deliberately preserving supply to its main customers – large industrial users and essential services – even during power outages.

The final issue is that Eskom could get more capacity from its pumped hydro systems. These systems use excess electricity at night to pump water to elevated storage dams, from which water is released during the day to meet the higher demand during daylight hours. During the week of May 12-19, capacity utilization of pumped hydro was only around 38%.

If there had been enough power during the day to fill the reservoirs, Eskom could have added 1.7 GW of generation capacity by early evening, fully utilizing the pumped hydro capacity and avoiding the need for load shedding. This daytime electricity could have come from the renewable energy program, had the Department of Mineral Resources and Energy followed the construction schedule.

Energy supplied by solar power plants.


What are the options for Eskom, other than starting the construction program?

To answer this question, we need some basics about energy systems. South Africa has a diverse energy system. Electricity is obtained from coal (the largest source), wind, solar, hydro, nuclear, diesel and imports.

Wind, solar and nuclear cannot be controlled by the operator. Gas, hydro-electric, water pump and diesel canister. Coal falls somewhere in between. Eskom’s role as system operator is to mix all sources to meet demand.

The difficulty is that demand and supply are variable, as shown in the image above for solar. It’s akin to running a catering event when you have no idea how many guests will be there or how many meals will be delivered.

Thus, Eskom follows a few simple rules (like other energy system operators). The rules are to first use sources he can’t control (wind, solar, and nuclear), then add the coal-fired plants, then supplement with hydro and pumped hydro. And if there is still a shortfall, bring in the gas and diesel turbines.

The most obvious solution to Eskom’s immediate problem is twofold:

  • bring more renewable energies, in particular wind and solar, independent power producer procurement program.
  • make greater use of pumped hydroelectricity using all additional low-cost energy sources available from independent power producers and elsewhere.

This approach has already been described in my previous post covering the Independent Power Producer Supply Scheme. I criticized the requirement for the independent power generator program and argued that interconnecting generators would reduce costs and increase system resilience. It is precisely this arrangement that will provide a solution to the short-term problems within the national network.

In the longer term, the country needs to properly implement the 2019 Integrated Resource Plan, even though it clashes with the coal, gas and oil plans of the Ministry of Mineral Resources and Energy. interests. If the country does not start the 2019 plan now, it will lead to the disappearance of Eskom as an energy producer, as users are forced to turn to other sources.

This is what it will take to keep South Africa’s struggling power company running

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