BizNews Premium subscribers who participate in the interactive Energy WhatsApp group have benefitted for some months from insights posted there by tribe member Wietze Post, a Dutch-educated engineer. Over the next few weeks we will publish a series of articles which he has written especially for the BizNews community, sharing his thoughts on where South Africa’s energy landscape is headed. A must-read for anyone who wants a rational perspective on the economy’s most critical factor. Here is the first of them.
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What will happen to SA’s power supply in 2024, and beyond? (Part 1 of 4)
By Ir. Wietze Post*
Load-shedding in 2024 will be much like 2023. South Africans will install many more solar, wind, and battery plants in 2024 and beyond. These plants will improve the power supply with few blackouts remaining in summer 2026/7. Yet winter load-shedding will likely be worse during the next few years. Even so, a lot of (private) projects are in the pipeline.
Eskom’s outlook for the year ahead is more pessimistic than their outlook at the beginning of 2023. So that doesn’t bode well.
Many see the rapid roll-out of solar plants throughout the country. They think we’ll soon have less load shedding. That may be so. Unfortunately, the old coal-fired power station failures are escalating. Any failure may be the unit’s last. Thus, Eskom’s capacity is eroding. South Africans may add solar plants too slowly to keep up with Eskom’s degrading capacity. This issue is likely to confront us repeatedly during the next decade.
The State/ Government/ Eskom will install little, or no, generation capacity. Eskom will install many batteries to manage the grid.
Subsidies, insofar as they exist, have little impact on renewable plant installations. Solar, wind, and batteries are an easy, low-cost solution. That’s why the private sector is using them to solve their energy problems.
The private players each seek the lowest-cost solution for their particular situation. They have scant regard for how their actions will influence the collective grid. There’s nothing wrong with that. Collectively, they will eventually displace all Eskom’s generators from the grid. Those who don’t install generation plants may have an irregular supply. They will depend on other’s excess (and discarded) yield to meet their needs. I expect the transition will be largely complete by 2034. Then we’ll have a network of mainly residential, commercial, and industrial generators.
I anticipate that some municipalities will play a significant role in energy generation. Eskom will represent about 20% of the total generation capacity in 2034.
Replacing a coal plant with solar power.
Let’s consider the case of replacing a good coal plant with only solar power. We need about five times the generation capacity to replace a coal plant’s annual energy yield. So, 5 GWp of solar panels for every 1 GW of an effective coal unit. For wind turbines, matching the capacity is usually a bit better, e.g., 4 to 1. These capacities of solar or wind will generate the same energy over a year as a coal plant. But much of the energy will arrive when we don’t need it. Solar or wind plants often won’t deliver at the instant that we want the energy.
It’s better to have a balanced mix of wind and solar generators for a stable supply over an entire year. The mix – together with storage, and the grid – can provide a steady and reliable supply.
Eskom’s fleet availability is low and we’re used to their low performance. So the bar to replace them is not as high as for a well-performing fleet. Thus, about 3X – instead of 5X – of renewable capacity is enough to replace an average coal plant’s output.
South Africa demands about 35GW peak power from Eskom’s grid, in winter. During a summer day, demand could be 20GW. On a summer’s evening, peak demand can go to 25GW. The lower summer demand – compared with winter – is partly due to rooftop solar displacing Eskom. The energy cannot be seen by Eskom as it is used “behind the meter”. Thus, SA is using more than 20 or 25GW, but Eskom can’t see how much.
Besides the above, we need to generate much more energy. That is, we also need to supply unmet demand. “Unmet demand” is the power need that shows up when more power becomes available. When power is reliable and cheap, people use much more power. New industries will start. They can’t exist when power’s uncertain and expensive.
Oddly, because of unmet demand, we’re likely to have low-level load shedding for many more years. Even as we achieve our targets, the goalposts will move. Energy will become cheaper, abundant, and mostly reliable. Yet, that will cause shortages when many people want more cheap power at the same time. The latter will result in load shedding.
Imagine energy supply is reliable and easily available, and it costs half of what it does today. We would probably use twice as much as we do now, perhaps more. That’s where we’re heading. There’s a huge unmet demand for reliable, low-cost electricity.
Demand management is a tool used by the Eskom network operator. Agreements are in place with large power users to shut down part of their operations when asked. These customers are paid to reduce their power demand.
This is an unfulfilled demand. When more power is available the unfulfilled demand will reappear. Thus our nation’s energy consumption will increase.
Some countries have a high proportion of renewable plants. They use another type of demand management. Regularly the network operator will ask users to absorb excess energy. The energy is usually sucked into large battery banks. In some cases, it’s stored by pumping water into a reservoir on high ground.
Batteries are common in renewable projects. These include residential, commercial, and industrial photovoltaic (PV) plants. Thus storage is widely distributed. On a larger scale, solar and wind farms include batteries. The owners may install the batteries at the generation plant. They could also be put at a nearby substation.
Grid-scale battery facilities are installed globally. These are batteries which may have more than 1GWh of capacity. Besides supplying energy, they can be used in a power hub to manage the frequency.
South Africa has grid-scale batteries. The latest of these is at a sub-main in the Hex River Valley, close to Worcester.
Batteries are usually the cheapest, and quickest, storage solution. Instead of constructing a hydro storage reservoir, install a big battery.
Existing pumped storage hydroelectric facilities are good locations for grid-scale batteries. Their transmission connections are already set up to receive and dispatch power. The batteries can soak up rooftop solar power around noon. Then they can dispense the energy during peak demand times.
A prime location for an energy buffering battery is at Steenbras Dam, in the Cape Town Metro. There’s a 180MW hydroelectric plant. The City would do well to place several 180MW/200MWh battery banks at the switchyard. A 180MW/400MWh battery bank would be a good start. Later the City can expand it to 180MW/800MWh. The existing transmission facilities make this an obvious location.
Eskom owns the 400MW Palmiet-Rockview pumped storage hydroelectric dam. It’s on the fringes of Grabouw. This is another prime location for a grid-scale battery facility.
The example of Australia’s transition to a renewable fleet.
Australia is transitioning from a coal-based fleet to a renewable fleet. As with us, they suffer when coal plants suddenly trip, which tends to happen in summer. When a coal unit trips, a large amount of power instantly disappears from the grid. That causes grid instability. That doesn’t happen with a renewable grid. The grid becomes more stable when there’s a fleet of tens of thousands of generators. Thus any single turbine or house going off-grid has a tiny impact. Energy supply changes are becoming gradual and manageable.
Installers are educated and learning more. Thus they’ve realised that east-west facing panels are beneficial. The daily solar yield pattern is broader than with north-facing panels. Also, many more panels can be installed on a roof, with the same inverter, than with north-facing panels. Because panels cost so little these days, the plant delivers more energy at a lower cost per kWh. Thus the noon generation curve is up to two hours wider and the plant generates more energy.
Australia has smelters and many heavy industries. They have no nuclear plants. Their coal plants will be retired early as they’re no longer financially viable.
Australia’s electricity costs less now than a few years ago. It’s becoming cheaper.
Western Australia has a separate independent grid. They’re on track for a 100% renewable grid by about 2028.
Australia’s eastern grid is tracking to a nearly 100% renewable grid by 2030. South Africa can do that too.
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*Ir. Wietze Post has broad research, engineering, and business experience. Wietze currently operates as a project leader. He has advised C&I and NPO renewable energy buyers for several years. The title of Ir is an abbreviation of ‘Ingenieur’, which is awarded to MSc graduates at technical/engineering universities in the Netherlands. Wietze’s alma mater is Wageningen University. Wietze avidly follows energy developments around the world and in South Africa. In this series, he considers how global trends may play out in South Africa.