Batteries Will Not Replace Gas to Firm Up Wind and Solar

South Australian wind turbines were pretty much AWOL during the week ending 26th June, 2026. What did this week reveal? 

Geoff Russell 

 

 

Context

The record heat waves in Europe and the beginning of a possibly record-level El Niño are a reminder that fossil fuels need to be removed from our energy and industrial infrastructure. Even though Trump’s war shows how deeply dependent the world still is. Mind you, Australia got off relatively lightly with the Global South taking the big hits from fuel and material shortages. The billion-dollar question for Australia, as one of the last countries trying to do without the most eco-friendly energy source on the planet (nuclear power), is whether batteries can really replace gas to firm up wind turbines and solar panels. No other country is running the experiment. As I write this (June 30, 16:38), there isn’t much wind in Germany, where it is 9 am, so it is importing plenty of French nuclear power. It’s also importing from Switzerland, which also has nuclear power, complementing a tonne of hydro-power. Following Spain’s nationwide blackout in 2025, the very next day the grid operator switched to Reinforced Operations, meaning they required plenty of synchronous generators (nuclear, gas, hydro) to be running at all times to keep grid inertia high. Claims about that blackout not being due to renewables are exactly the same as those about South Australia’s 2016 statewide blackout not being due to renewables. Ignore what everybody says, and just watch what they do! In SA, they ordered the installation of 4 large synchronous condensers. In Spain, they just made sure plenty of such equipment was running all th the time to strengthen the grid. If you don’t know what synchronous generators and inertia are, then read this explanation.

Now let’s consider the South Australian grid during the week ending on the 26th of June, 2026.

The SA Wind Drought

The week ending on the 26th of June was a shocker for the South Australian electricity supply. Here’s the OpenElectricity graph showing where our electricity came from.

 

 

The green in the graph represents electricity from wind power. The 3 shades of pale orange below that are types of gas turbines and the purple represents imports from across the border in Victoria to keep our supermarket freezers and sewage pumps running.

Check the table on the right. Expand the image if you need to, it shows that we got just 35% of our electricity from wind, plus solar, plus batteries (WSB) during this week. During the past 3 years, the percentage of electricity from renewables has been levelling off. And there are good structural reasons to think it won’t climb much more.

 

 

Every winter, we get enough of these weeks to prevent the annual average from rising, despite having enough solar panels to supply 100% of our electricity during the day and similarly for wind.

An ABC article on the 28th of June quoted engineer Geoff Eldridge as saying batteries were not the answer to multiday wind lulls. The journalists also consulted SA Energy Minister Koutsantonis who replied as follows:

“[Koutsantonis] said the amount of large-scale battery capacity in the state would more than double to 2.5 gigawatts, or 2,500 megawatts, which would be able to power about 300,000 homes for eight hours.”

He’s clearly trying to suggest batteries would be sufficient if only we had enough of them.

Did the journalists bother to fact-check the statement?

School children learn the difference between power and energy as young teenagers. The webpage I just linked has it tagged as suitable for grades 6-8. It’s a US webpage, so the age of students learning this is about 11-13. Gemini tells me it’s similar in Australia, with the equations given to 15-17 year olds. Koutsantonis has either been misquoted or forgotten whatever he learned about this critical difference as a child. I wonder if Koutsantonis or the journalists were nodding off in Science classes thinking “Who on earth will ever need this stuff?”

So here’s a refresher. A watt is a unit of power; a gigawatt is just a bigger unit of power; it’s a billion watts. If one electric kettle is 1000 watts and another is 2000 watts, then the second will boil a litre of water twice as fast as the first. It’s of little use knowing the power of a battery without knowing how long it can provide that power.

You can have a 2.5 gigawatt battery that lasts for 5 minutes or 5 hours; big difference. A 2.5 gigawatt battery that lasts for 8 hours is 96 times bigger. So batteries are typically defined by two numbers: 1) the power and 2) either the length of time the battery will last or the amount of energy it holds, which will make the length of time obvious. Energy is measured not in watts but in watt-hours, the length of time the power will last. A 2.5 gigawatt battery lasting 8 hours needs 2.5 x 8 = 20 gigawatt-hours of energy. It would be called a 2.5GW/20GWh battery by anybody in the industry.

The current battery capacity in SA is 1.1 gigawatts for about 2 hours, or 2.2 gigawatt-hours (1.1GW/2.2GWh). So getting 2.5 gigawatts for 8 hours isn’t a doubling of our current storage; it’s about a 10-fold increase in the number of battery packs installed.

But what about the 300,000 homes?

We have about 808,000 homes in SA (Google it).

So let’s finish fact-checking Koutsantonis’s claim.

We used 15,000 gigawatt-hours of energy in 2025. Divide that by 808000, and then by 365 and then by 24. That’s the energy per hour per home, and then multiply by 8. You get about 17,000 watt-hours on average to supply electricity to a home for 8 hours.

Lastly, let’s take Koutsantonis at his word and assume we will have batteries that can supply 2.5 gigawatts for 8 hours. Such a collection of batteries would provide 17,000 watt-hours to about 1.2 million homes. So it looks like Koutsantonis intended to say 2.5 gigawatt-hours of batteries. Which means he is specifying the energy available without the power. This amount of energy would run about 147,000 houses for 8 hours. The maximum power required would be about 312 megawatts.

All of which is pretty confusing. It would be really nice if journalists and politicians spoke more precisely. You can’t fact-check people who just mangle the facts.

But it gets worse

But that’s being a bit picky, really.

The much bigger deception is to presume that this battery expansion will be a big step on the path to solving our wind drought problems.

So let’s do the math. Let’s double Koutsantonis’s battery promise and see what impact it would have had on this low-wind week.

So let’s pretend we have 5 gigawatt-hours of batteries. We’ll also assume they are magic batteries that can supply 10 gigawatts of power for 30 minutes or 5 gigawatts for 1 hour. Theoretically, building such batteries should be possible.

Let’s also assume that we build 50% more wind farms and increase our solar power by 50%.

That’s a huge increase in the state’s power supply. More wind, more solar, and more batteries; a lot more.

Will it be enough to cover the week ending the 26th of June?

I can’t use OpenElectricity for this exercise, but I have downloaded the data and written code to work out what would happen.

It’s conceptually simple. Just multiply the current wind and solar output by 1.5, assume 5 gigawatts of batteries and assume the same demand.

I’ll also ignore the needs of wind farms and batteries to make money.

So my model just assumes that any leftover wind and solar energy gets stored in the batteries, unless full. It also assumes that any electricity shortfall comes from the batteries if they have the energy, regardless of the power required or the price. In the real world, you can’t always get energy from a battery in one part of the state to a shortage in another because of network constraints. I’ll ignore that also.

Here’s the result.

 

 

The number to focus on is the “Shortfall” … that’s the sum of the difference between supply and demand.

We added 5 gigawatt-hours, a doubling of what Koutsantonis promised, and we added 50% more wind and solar generation, but we are still 135 gigawatt-hours short over the week. That monster supply of batteries was flattened during the first night and never recovered!

Here are some critical results in a table.

 

 

The 5 gigawatt-hours of batteries only supplied 11.58 GWh … because they were flat for most of the time and there was no excess wind or solar power to charge them. The maximum shortfall over an 8 hour period was 14.9 GWh. That doesn’t sound like a lot, but once your batteries are flat, they are useless.

Batteries and gas

The bottom line is that 5 gigawatt-hours of batteries shifted the proportion of WSB electricity from 35.5% to 36.7%. How accurate is my model? It uses the available batteries a little more than in the real world. I know this from the model estimate of curtailment to the actual curtailment figures reported by OpenElectricity. What about adding 16 gigawatt-hours of batteries, which is what the Australian Energy Market Operator (AEMO) suggested as possible in their 2024 Integrated System Plan (ISP)? That will increase the WSB share to 40.4% of demand.

So more batteries have a negligible impact on the WSB share on a low-wind winter week. And it’s these low wind weeks that pull down our annual average and prevent us ever getting to 100% renewables (or even 80% renewables).

The Australian Financial Review (AFR) (June 30) contained an interesting story with the headline “Gas power forecasts drop 39pc amid battery boom”. It’s pure clickbait, but it worked; I read it. It shows gas use under the AEMO ISP, comparing the recent 2026 ISP with the previous 2024 ISP. Here’s the AFR rendering of the chart.

 

 

The 2026 modelling has gas dropping to almost nothing by 2032. That’s just obviously wrong. Who thought this a credible prediction? Then it shows gas increasing until, by 2050, it’s back pretty much exactly to where it is now.

Who looked at these graphs and suggested that attention grabbing headline?

SA has more batteries relative to its electricity demand than any other state, and it’s pretty clear that doubling or tripling that storage makes little impact on the gas used on low-wind days. So it’s hard to see why any credible battery increases will significantly reduce gas use.

SA’s “firming tender”

On May 29, RenewEconomy reported on the tender in South Australia for technology that could “demonstrate at least eight hours of storage”. It was open to both gas plants and batteries. The successful bidders were five battery projects that committed to providing half a gigawatt for about 8 hours (just over 4 gigawatt-hours of storage).

“The tender – officially known as the Firm Energy Reliability Mechanism – was designed specifically to ensure supply was available to the market at times of system stress as it reached and moved beyond its target of reaching 100 per cent net renewable by the end of 2027.”

If 16 gigawatt-hours of magic batteries won’t deal with the “system stress” at the end of June, then 4 gigawatt-hours certainly won’t cut it. For that event, all the batteries would be flat well before the end of the first night of low wind, and SA would continue to be sucking on Victorian fossil fuels to keep the lights on. Consult the table at the start of this article and think about how likely we are to get to 80% renewables by the end of 2027, let alone 100%.

Making money and building batteries

Now go back to the first image in this article and look at the average prices/MWh for the various technologies.

Gas attracts a premium price in our market-driven system because it’s dispatchable. When the wind isn’t blowing and the sun isn’t shining, the laws of supply and demand determine the price. Most of the gas is combined-cycle gas turbine (CCGT) (Combined cycle), with a price of $436/MWh (43 cents/kwh); this is the most efficient form of gas turbine. Batteries came in at $434/MWh (43 cents/kwh). This is the wholesale price; the retail price will be about double because network costs always dominate the price of electricity. After all, that’s the hard and complex part of delivering electricity. Generation is the easy bit. Calling something “easy” when it’s the product of millions of person-hours of scientific effort is perhaps annoying, but that’s what we do with miracle technologies: take them for granted.

Why is electricity from batteries so expensive? There are two costs. First, you have to build (import) your battery, then you have to pay to charge it. Paying to charge it during a period of excess is pretty cheap. When rooftop solar is booming in SA. Everything else is excess. Nobody can sell anything. So batteries are cheap to charge. But during a lull in the winter wind, there is little to no excess. The batteries are paying top dollar to charge and need to recoup that, as well as the repayments on their capital costs.

If you actually want to make a difference to the use of gas for covering renewable gaps, then you stick a baseload source on the grid and slash the size and duration of the gaps. The obvious clean baseload source is nuclear. You also need to remove the assumption of markets being the only way to manage electricity. The market volatility in today’s broken electricity market just breeds hedge players and traders. Here’s a chart showing the change in prices in SA between 2009 and 2026. You can see the remarkable rise in volatility.

 

  

When something is broken, fix it.