South Australia’s remarkable 100 per cent renewables run extends to over 10 days

South Australia has just chalked up what is undoubtedly a world first – a run of more than 10 consecutive days over which the average production of wind and solar accounted for 100 per cent of local demand.

No other gigawatt scale grid in the world has come close to this amount of “variable renewable energy”, or for such a long time.

RenewEconomy reported on Monday that South Australia had just enjoyed a seven day run of wind and solar that produced more than 104 per cent of average demand. Closer inspection proved it was even more impressive than that.

According to Geoff Eldridge at data providers GPE NemLog2, the supply of wind and solar averaged 100 per cent of local demand for 10 days and 9 hours (a total of 249 hours) from 08:20 on Friday, December 9, to 1720, Monday, December 19.

Over that time, rooftop solar contributed 26.3 per cent – and dominated daytime production, sometimes up to 92 per cent of local demand.

The biggest contribution over the 10 days and a bit came from wind energy, with a 67.6 per cent share over that time, while large scale solar – heavily curtailed because of negative prices and the impact of rooftop PV – contribute just 6.1 per cent.

It is, as many analysts have said, a remarkable event, and not just because so many people believe it is, or at least was, impossible.

There are a couple of important points to make. South Australia is connected to another grid (Victoria) so excess generation is exported, or stored in the three operating big batteries, and many household ones. Only a small amount was imported from Victoria over the seven days.

A lot of wind and solar was curtailed during that time, a total of 2,590GWh, or nearly 10 per cent of potential production.

Another view is presented by Dylan McConnell, now of UNSW, using OpenNEM data. He puts the stretch of more than 100 per cent renewables at 10 days, 18 hours and 45 minutes, with the mean price over that period averaging minus $3.26/MWh.

McConnell puts the wind curtailment at 10 per cent of the theoretical potential, and large scale solar at a hefty 35 per cent of theoretical potential.

The principal reason for this is economic curtailment, particularly in the middle of the day when rooftop solar takes centre stage and was accounting for up to 92 per cent of demand by itself, sending prices negative. Some wind and solar farms are obliged to switch off when the prices fall below zero.

South Australia does not yet have enough storage to soak up the excess load, but that may be at least partially solved by the addition of at least three new big batteries – at Blyth, Bungama and Tailem Bend – and likely more – and the completion of the new link to NSW with an export capacity of up to 800MW.

Excess wind and solar could also be absorbed by green hydrogen electrolysers – which will both soak up surplus output, but also feed into one of the world’s first large scale hydrogen power plants, to provide green power back into the grid when the wind blows less and the sun is not shining.

There are plenty of large scale wind and solar projects busting to get into the grid to add many gigawatts of new capacity, including the Goyder South hub, which could have up to 2GW of wind and solar capacity.

The first 414MW stage is already under construction and will help lift the state to a “net” 100 per cent renewable benchmark within a few years. The state has averaged 67.8 per cent over the last 12 months, and more than 90 per cent so far in December.

During the 10-day period that averaged 100 per cent wind and solar, South Australia only had a minimum amount of gas generation – not for energy needs, but for “system strength” and other vital grid services.

This need is likely to be redundant in a few years when the new link to NSW is built, and as more “grid forming” inverters that mimic the properties of coal, gas and hydro, are constructed.

Then, we will see an even more remarkable landmark – one that so many people still insist is not possible – a gigawatt scale grid running for a period of time on wind and solar only, with no fossil fuel generation at all.

Meanwhile, another energy expert, David Osmond, who works at Windlab and produces a weekly simulation of Australia’s potential for renewables with just five hours of storage, across the whole National Electricity Market, not just South Australia.

He says the last week has been record breaking.

“Record high solar production along with good wind resulted in record excess generation, and almost no need for any storage during the entire week,” he says, adding that this meant the whole grid could have been 100 per cent renewable, assuming enough capacity is actually built, and 99 per cent over the last 69 weeks.

You can read a detailed summary of his earlier simulations over a 52-week period here: A near 100 per cent renewables grid is well within reach, and with little storage