What It Will Take For South Africa’s Ailing Power Utility To Keep Going

The chief operating officer of South Africa’s electricity utility, Eskom, warned in May that the government should urgently start building new generating capacity. This was in reference to an existing new build program that has been in place for at least a decade.

The country’s Integrated Resource Plan of 2019, a cabinet approved document, sets out the timelines for decommissioning coal-fired power stations and adding 44GW of new capacity, including 18GW of wind energy and 8GW of solar (photovoltaic).

This programme is far behind the country, which continues to struggle with regular power cuts and antique power stations. Outages are a regular ocurrence which are estimated to cost the country’s economy about US$1 million an hour.

South Africans are well aware of the energy crisis. In my work on energy systems, transitions, I started to question the true nature of this crisis and how Eskom should respond. My views are informed by Eskom’s data portal, a rich source for insights on South Africa’s complex electricity system. This portal provides detailed information about electricity demand and supply. It provides information on energy sources, levels of storage, and the extent to which there has been loadshedding (power cut) on an hourly base.

I examined the data on demand and supply for May 2022. It revealed three main trends: demand has fallen; power cuts aren’t as big as they could be; and there’s scope to get more out of the system using renewable energy sources.

South African power supply trends and demand trends

The dataThree key trends emerge for the utility. First, Eskom dropped 6GW (roughly 21%) of its demand in less than a year. This is due to many customers who aren’t paying their bills being disconnected. Several large clients, including mines, have started generating their own electricity.

Below is a comparison of two days’ demand. One from June 2021, the other from May 20,22. It reflects actual demand, not Eskom’s supply. The difference in demand between the two countries is astonishing. At this rate, South Africa simply won’t need Eskom in five years.

Another interesting fact is that power outages are very small in relation to total energy delivered. Eskom generated about 1.6% of all energy produced over the week of 12-19 May 2022 by delivering 4,271 MWh and cutting 70 MWh.

I’m making this point to show that power cuts could get much worse unless the rebuild programme begins soon. One reason that the power cuts attract high media attention is that consumers bear a disproportionate share of the energy cuts relative to Eskom’s anchor customers.

For instance, under level 4 where power cuts can last for over five hours in a day, lower end users have power for only 67% of the day – meaning 33% of their power supply is cut. However, the overall energy savings across the entire system is only 10%. This suggests that Eskom deliberately preserves supply for its anchor customers – large industrial users and essential services – even during the power cuts.

Eskom could also get more capacity from its pumped-hydro schemes. These schemes pump excess power at night to water storage dams. The water is released during daylight hours to meet the higher demand. Only about 1% of the pumped hydro capacity was used between 12-19 May. 38%.

Eskom could have added an additional 1.7 GW to its generation capacity in the evenings if enough power was available during the day to replenish the reservoirs. It would have made full use the pumped hydro capacity, and avoided loadshedding. If the Department of Mineral Resources and Energy had followed their build schedule, then that daytime power could come from the renewable energie programme.

Eskom’s options

What other options are available to Eskom than the start of the build program?

This question can only be answered if we have some basic knowledge about energy systems. South Africa is home to a variety of energy sources. Coal is the largest source of electricity, followed by wind, solar, nuclear, and diesel.

Wind, solar and nuclear can’t be controlled by the operator. The operator can control gas, diesel, hydro-electric and pumped hydro. The coal is somewhere between these two. Eskom’s role as the system operator is to blend all the sources to match the demand.

It is difficult because both supply and demand are subject to change, as seen in the solar image above. It’s like managing a catering event where you don’t know how many guests are coming or how many meals will need to be served.

Eskom follows a few simple rules, just like other energy system operators. First, Eskom must use the sources it can’t control (wind and solar), then it must add coal power stations and finally, hydro-electricity or pumped hydro. You can also bring in gas and diesel turbines if you still have a shortage.

The most obvious solution to Eskom’s immediate problem is two-fold:

  • Increase the import of renewable energy, particularly solar and wind, through the Independent Power Producers procurement program
  • You can make more use pumped hydro by using all sources of low-cost, additional power available from independent power producers.

This is the same approach that I described in my previous publication about the procurement program for independent power generators. I criticised the programme’s requirement of stand-alone power producers and argued that the interconnectedness of the producers would reduce cost and increase resilience in the system. This arrangement is what will solve the short-term problems in the national grid.

In the longer term, the country needs to properly implement the 2019 Integrated Resource Plan, even if it clashes with the Department of Mineral Resources and Energy’s coal, gas and oil interests.

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