Wietze Post: Future of energy – refiners, smelters and other opportunities for renewables

Refineries, smelters, and metallurgical companies, known for their substantial energy consumption and environmental impact, are undergoing a transformative shift towards sustainability. In Australia, where aluminium benefaction alone accounts for 10% of electricity consumption, smelters are rapidly transitioning to renewable energy sources. This green revolution is not confined to Australia; countries like Norway, Australia, Namibia, and Morocco are exploring the potential of ‘green’ ore refining capabilities.

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Post 2 of 4By Ir. Wietze Post

Economically vibrant countries want to attract global commerce and industry. Cheap and reliable electricity supply is a must.

Besides, some trading partners impose carbon taxes on their imported goods. Thus our exporters must use the least polluting energy supply that they can find.

Refiners, smelters, and opportunities for renewable energy.

Refineries, smelters, and other metallurgical companies are amongst the most energy-intensive industries. They scour the world for the lowest cost electricity. They are amongst the most polluting industries when powered by fossil fuels. So there is a powerful movement towards ‘greening’ these industries.

In Australia, aluminium beneficiation is the single largest consumer of electricity. It’s responsible for roughly 10% of consumption. The Australian smelters are switching to as much renewable energy as quickly as they can.

A renewable energy supplier is an attractive partner for a metallurgical plant. This power can come from a grid, a group of plants, or even a single large generator. A direct transmission line to an ore refinery is useful.

Norway has a lot of hydropower. As such it’s developing a ‘green’ ore refining capability. Australia is also developing this opportunity. Perhaps Namibia and Morocco too.

South Africa could also produce ‘green’ refined metals. Consider a new harbour at Alexander Bay | Peacock’s Bay in the Northern Cape. The hinterland contains a lot of ores. The Northern Cape has expansive areas for solar and wind plants. Metallurgical processing plants can be put close to renewable energy plants. A railway line can run from the mines to the harbour. Along the way, the trains can unload ore at the refiners. Later they can take the refined metal products to the harbour. The trains can be drawn by battery-powered locomotives.

Battery-powered ore-train locomotives will enter service in Australia’s Pilbara region. The first has been delivered. The locomotives use regenerative braking. They charge their battery on the loaded downhill run from the mine to the port facility. On the return journey – with empty wagons – they use the stored energy. With the correct parameters, little external recharging is needed to maintain the cycle. Links to more information are at the bottom of this article.

The difference between power and energy.

A woman is busy in the kitchen. She struggles to open a jar of gherkins, so she takes the jar to her husband. He opens the lid with a quick turn. He exerted power for an instant and opened the jar. He can exert his power at any moment. Yet if he had to open 1000 jars in quick succession he would probably get exhausted. In the latter case, he’s used up his energy. Power is instantaneous, while energy is the exertion of power over time.

For batteries, generators, solar panels, and wind turbines, power is measured in kW (kiloWatt). Power exerted over time adds up to energy and is measured in kWh (kilo-watt-hour). The units on your electricity meter are also measured in kWh.

What is “demand”? What is a supply-driven grid?

SA’s grid is designed with the idea that power will always be available when you want it. That implies that there must always be overcapacity on the grid. If you flick a light switch, the light must come on. In other words, if you “demand” light – you “demand” power – it will instantly appear. All the requests for power on the grid add up to the grid’s “demand.”

Load shedding is a big deal. It breaks the implicit promise that our power demand will be met whenever we want it.

A grid – the fleet of generators – can also be designed differently. The generators can be focused on supply, rather than demand. In a supply-driven grid, we would wait for power to be available before attempting to switch on the lights. Think of living out in the bush with your diesel genset. You first start the generator before switching on the lights. And then you carefully manage the load on the generator so it doesn’t trip.

Some industrial processes depend on this idea. They only run when they’re sure that energy will be available, and that there’s excess power on the grid. This implies that they’re last in line, they’re always last to get energy. There are consequences to such a design. They could scale the industrial process to have overcapacity. They may only receive 6 hours of power per day. Then they might make their capacity 4X as big as they would with 24 hours of power.

This design principle also applies to renewables-based grids. Invariably, many solar power plants in a grid cause power excess around solar noon. This means that more power supply becomes “worthless” around noon. Some industries could scale to large overcapacity. Then they could use “free” electricity around noon.

The drive to lowest-cost electricity and consequences for large generators.

Countries, and people, are driven to get the lowest cost of electricity. In SA, that leads to consumers taking matters into their own hands. Their particular solution depends on their needs and resources. A house may install a rooftop solar plant. A mine may have solar, wind, and wheeling arrangements. A farm may have a digester, or hydro plant. In each case, a renewable plant is the lowest-cost solution.

All these individual choices eventually lead to a renewables-based grid. The consumers feed their excess power into their local grid. Eventually, a breakeven moment arrives. That’s when private plants generate enough power to please themselves, and their neighbours. Then there’s no need for power from grid-scale generators. Thus those large generators must switch off their supply so that the grid is not overloaded.

Many solar panels face north. Small solar generators simply dump their excess power on the grid. That will cause a particularly pronounced power surge around noon. The abundance of noon power means nobody needs more supply. Anybody wanting power at noon can get it for free. That’s what’s happening in some renewables-based grids.

During sunny and windy periods, the wholesale cost of power goes to zero. It often goes below that, into negative numbers. The negative numbers mean that consumers are paid to use energy. They’re encouraged to use energy to keep the grid in balance.

Coal and nuclear plants can ill afford to shut down. It costs them too much to start up again a few hours later. Thus these large generators are forced to pay to send their power into the grid. Paying to send your power into the grid is not a good business model. So coal and nuclear plant owners struggle to compete with renewable plants.

Solar and wind farms can suffer a similar problem. Potentially they could generate a lot of power. But they may discover that rooftop solar plants have already filled the grid’s demand. The generation farms would overload the grid if they put their power into it. They can pay penalties to dump their power into the grid. Some customers would accept the power and be paid to do so. To avoid penalties, renewable farms curtail their power output. They shut their wind or solar farms down. They stop sending power into the grid. Thus the owners avoid paying penalties.

You may wonder about the fairness of who gets to send their power into the grid. I’ll address this in future. The issue is actually that there are times when there’s virtually no demand on the grid. Nearly all houses and businesses will have their own power plant. Each rooftop plant may meet its owner’s needs at some point (e.g., around noon). Thus no customer demands any power from the grid. The grid demand is zero. So no generator, big or small, can send energy into the grid. This always hurts the large commercial generators the most.

The casual observer may wonder about stationary wind turbines despite apparently windy conditions. In reality, renewable plants are conserving their money. Meanwhile, the coal and nuclear plants are paying penalties.

Another aspect is the typical wind profile during the day and night. Usually, there’s stronger wind at night than day. Wind turbines are designed to operate during strong wind conditions. Thus they usually operate at night, when it’s dark. During the day they’re often not spinning. The casual observer sees the turbines in the light of day and then concludes that the wind farm is inactive.

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