In September 2016, a ‘50-year-event’ storm occurred in South Australia. Power system voltage transients caused nine wind farms to shut down, and two large wind farms – the Hornsdale wind farm and the Snowtown wind farm – reduced output by 86 MW and 106 MW respectively in the space of one second. The Heywood interconnector flow increased to over 850 MW and both its circuits tripped out as a result of the overload. Supply was then lost to almost all of the South Australian region as the Torrens Island power station, the Ladbroke Grove power station, the Murraylink interconnector and all remaining wind farms tripped.

There has been much political comment on this matter, most of it uninformed. The nub of the matter is that, in a power system with wind farms, given a weather event, there is a real possibility that the wind farm generation will shut down (owing to overspeed or voltage transients) and the system will be overloaded and shut down. The way to stop this from happening is to balance the wind farm output with an alternative generation source that can take over, literally at a moment’s notice. Such generation does not exist in fossil-fuel-fired systems – neither a gas turbine nor a coal-fired station can pick up 192 MW in a second or two. So, the best idea is not to have wind farms being the primary generation source. Install them, sure. But not as reliable generation.

However, instead of seriously doing some decent power system analysis, South Australia has adopted the white night approach: a big battery supplied by Tesla/Elon Musk. It is connected to the power system at the Hornsdale wind farm and can deliver 70 MW for ten minutes and 30 MW for three hours. It discharges in 80 minutes and takes three hours to charge up again.

Research principal at the Institute for Sustainable Futures Dr Geoff James says: “The Tesla battery farm, like a modern Stonehenge aligned with the surrounding turbines, will shift wind energy production to make it more dispatchable and, therefore, more profitable. “At the same time, its high power capacity will be available in quick bursts to keep frequency in the right range.”

You know me. I am as impressed as my Internet dates are when they first meet me face to face. Boil this whole thing down. Tesla has a generator that can do 70 MW for ten minutes and 30 MW for three hours? And this is going to . . . ahhhh . . . what? Give enough time to get a gas turbine going? You lose 192 MW wind power and you prop it up with a 70 MW battery for ten minutes? Hello?

And bear in mind that this is a battery. Once it is discharged, it has to be charged up. It will take at least 3.5 hours to do this – so, after the power failure, the moment all the power system gets back together, you will have a 100 MW load of battery charge in addition to the load you had before and the load will have gone ‘cold’ in the interim and you will have to prioritise consumers before batteries and so the battery will only be back on line in a few days. Its only benefit is that it has power available in one second. But, since it is inverter based, it can, and will, disconnect for voltage transients of two seconds.

Also, there is the size. A 100 MW power source in power system terms is small. The backup power to the Cape Town Waterfront complex is about 30 MW. Cape Town demand is about 4 000 MW. What difference does a 100 MW battery make to anything? Well, it probably makes a big difference to Musk’s bottom line. At a cost of R2.4-billion, it really should. The greens must be very proud.