Energy expert Chris Yelland said that while the probability of a national blackout happening is very low, the consequences can be devastating.
Speaking at the 2015 MyBroadband Cloud and Hosting Conference, Yelland said a national power blackout occurs when electricity demand exceeds supply and Eskom does not take appropriate action.
“When electricity demand exceeds supply, you are overloading generators, cables, and transformers. If you don’t do anything about it, one of these things will trip out,” said Yelland.
“When one of these components trip out, you are reducing supply – overloading the system even more. This causes a cascading tripping of systems, which causes a total grid collapse.”
Such a blackout can last for up to two weeks, said Yelland, because it will require a full restart of the SA power system. This will have major consequences.
He warned that a blackout will result in water, food, and fuel shortages, telecoms network downtime, civil unrest, and looting.
How Eskom prevents a national blackout
To safeguard the grid against a blackout, Eskom implements load shedding to reduce electricity demand as it nears the supply capacity.
A second line of defence is under-frequency load shedding, when an automated system kicks in when the electricity frequency drops below 50Hz.
A third line of defence is islanding, where the country is split into areas which are not interconnected. A blackout in one region will not affect the whole country.
When all of these defences fail, the country may experience a national blackout.
The risk in the event of a national blackout
Yelland said the probability of a national blackout is very low because of the manual and automatic measures to reduce demand.
However, because of the severe consequences in the event of a national blackout, an emergency plan is of value.
He provided the following equation to establish whether you should invest in an emergency plan.
Risk = Probability x Consequences
The decision to have an emergency plan depends on your individual risk. The low risk and severe consequences makes this a challenging question to answer.
Some emergency plans are in place
Preparing for a national power blackout is already happening. The City Press reported that Eskom secretly conducted a nationwide blackout simulation in March 2015 to test how its systems would handle a total loss of power.
This followed reports that the South African government and the US embassy have emergency plans in place in the event of a blackout.
The City Press reported that the US embassy in Pretoria “has drawn up an evacuation plan partly designed to get its staff out safely if the lights go off in South Africa once and for all”.
South Africa’s top leaders will also be moved to safety. Reuters reported that president Jacob Zuma and his cabinet would be taken to a secret location if a blackout occurred.
The report further stated that “soldiers would be deployed at key sites such as the central bank and South African Broadcasting Corporation”.
Cape Town mayor Patricia de Lille said they have set aside R245 million to accommodate emergency preparations for a national blackout.
What you can do to prepare for a national blackout
While most South Africans do not have the resources of the government or large companies to prepare for a power blackout, there are things which you can do to mitigate its effects.
Basic power backup solutions – like a generator, battery backups/UPS, or solar power – will be valuable. Having alternative energy sources like wood, candles, and gas is also good.
A basic “survival kit” is also advised. This should include adequate water, food, a battery-powered radio, a torch with batteries (LED if possible), and personal sanitation items.
Other items which are always welcome include a first aid kit, a whistle to signal for help, and a wrench or pliers for turning off utilities.
Having some cash around can be a life saver, as ATMs, cash registers, and credit card machines won’t work during a prolonged blackout.