HomeIndustry SectorsAsset MaintenanceOp-ed: South Africa's 100MW threshold has rhinos in the room

Op-ed: South Africa’s 100MW threshold has rhinos in the room

There has been a lot of discussion about the recent announcement that the limit on private electricity generation is being raised to 100MW from the previous 10MW threshold writes Dr Kelvin Kemm.

There has also been discussion about the difference between a permit and a licence. Most of the discussion which I have seen indicates a lack of understanding of the issues.

The debate predominately centres on whether private producers should be allowed into the market, as if it is merely a market-share issue. But there is much more to the story than is being revealed.

There are two huge rhinos in the room (I am tired of having elephants in the room, I prefer rhinos). The two rhinos are:
1. the quality of the electricity produced; and
2. the effect on the National Control Centre.

Understanding the critical technical limitations at end-user level

South African electricity for home use is delivered at 220 Volts (V) and with a frequency of 50Hertz (Hz). The current, measured in Amps (A), can vary depending on the size of the circuit breaker you have in your house, which in turn depends on how large the cable is which feeds your house.

In some office buildings, you may have noticed ordinary 3-pin plug sockets in the wall but also some 3-pin sockets painted red. Staff may have told you that the ‘red electricity’ is ‘clean electricity.

The 220 voltage is important because if it drops lower than 220V many devices will not work. But much worse is if the 220V goes above 220 then it can destroy electrical systems. If somebody plugs a large welding machine into the office wall plug and flicks the switch it can send an electrical pulse backwards into the wall which causes a voltage ‘spike’ that travels along to other plug sockets, possibly damaging other equipment.

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Sensitive computer equipment is particularly susceptible to spikes. So in some companies, they install a special circuit that has extra electric components in it to protect against spikes. The convention is to mark the plugs red. You’re not supposed to plug a vacuum cleaner, or your electric guitar, into a red plug. This is out of respect for the folks who have computers plugged into red plugs.

In the 220 volt system, the 50Hz frequency is also very important. That 50Hz controls electric clocks. All computers have electric clocks in them. This becomes important at the stock exchange and in banks when large amounts of money are transferred internationally, and the clocks play a role.

Clocks are also important for radar systems, and hundreds of other applications. So you can’t fool with the 50Hz. The 50Hz is also important in the Eskom transmission system and if the 50 varies by even a small amount it can cause huge problems.

The red plug and welder scenario is not only important in the office context but is also very important for the entire country. You can’t just allow people to switch large amounts of power, like 100MW, in and out of the system. The quality of the voltage and 50Hz frequency is critical. As a comparison; you can’t allow just anybody to supply pills to the pharmacy because he says he can produce them cheaper. It is critical to believe in the quality of pill production.

Solar and wind power are inherently highly variable. If dense clouds come over a solar array the power disappears instantly. The solar supplier can’t guarantee that there will be no clouds or rain.

How the 100MW threshold could impact Eskom’s National Control Centre

Then we come to the other rhino in the room.

South Africa’s power market is divided into half a dozen macro electricity areas. The power going out of these areas is all controlled by the Eskom National Control Centre at Simmerpan. As a comparison; imagine a national railway traffic control centre. You can’t just let any train go down any line in any direction, at any time.

The national control of electricity has to balance everything up, so to speak. If a power station generator fails then Simmerpan has to route more power into that area from somewhere else. Ideally, they are supposed to have 15% spare capacity at all times, so that there is always enough to reroute to anywhere.

But remember; the power lines are not all the same size. So you can’t put big power through a small line. The whole routing component is a large complex job. When there is no 15% spare capacity; like now, then even a modest power station failure can lead to loadshedding. The control staff then have to decide which neighbourhoods to switch off and when…until the breakdown is fixed.

So a primary issue with the new 100MW private generation move is: can a potential generating applicant guarantee a reliable quality supply of electricity. Also, can they guarantee a consistent supply, such that they don’t just increase the challenges for the experts at the National Control Centre?

When Minister Mantashe appears hesitant to just open the floodgates expected from the 100MW threshold he knows how much trouble can be caused by the wrong type of flood.

Dr Kelvin Kemm is a nuclear physicist and is CEO of Stratek Business Strategy Consultants, a project management company based in Pretoria. He carries out business strategy development and project planning in a wide variety of fields for diverse clients. Stratek@pixie.co.za

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