Renewables within a whisker of grid parity

Hey Reader, welcome to The Energy's weekly data newsletter. This week we kick off our regular seasonal review of the energy mix in the NEM and SWIS.

Spring break

Renewable energy came within a whisker of parity with fossil fuels in the eastern states National Electricity Market grid mix for Spring 2025, as the transition defied the naysayers.

Western Australia’s South West Integrated System also came close to parity, driven by a huge surge in utility solar generation. In the NEM, big jumps in wind, utility and rooftop solar all helped shift the balance away from fossil fuels. Battery discharge surged two to three-fold in both systems, reflecting accelerating investment — with no end in sight — in storage.

Gas was the big loser and black coal a surprise gainer in the SWIS, while in the NEM brown coal, gas and hydro all retreated sharply, reflecting the larger role of batteries.

That drove emissions intensity down to record lows, in the NEM’s case comfortably below the 500 kilograms of CO2 per megawatt hour mark, and in the SWIS well below 400 kg/MWh.

This was a pretty good Spring by the standards of this most benign season, with lots of wind and sunshine in the eastern states and lots of sunshine in the West.

But one good Spring does not an endless summer make. There’s a long way to go to reach clean energy dominance across the seasons, let alone during late autumn and early winter solar and wind droughts.

National climate goals also remain stretch targets, but encouraging progress was made in Spring 2025.

The Energy decided to analyse seasonal grid data after some feedback in response to its regular quarterly updates, which straddle seasons. Charts for this newsletter were prepared by Juliette O’Brien at onlyfacts.io using Open Electricity data.

Renewables came within a rounding error of parity in the NEM this Spring, and got close in the SWIS. *Source: onlyfacts.io*

Missed by that much

Renewables advocates have been excitedly posting charts showing renewables reaching 50.1% of the NEM mix in the month of November, and utility batteries discharging more energy than peaking gas plants.

These are notable achievements in the transition. But how much better to do it over an entire season? It was not quite to be this Spring.

The data shows renewables got to 49.9% in the NEM — a rounding error from parity. Fossil fuels sat at 50.1%.

In the SWIS, renewables made 49.1%, leaving fossil fuels at 50.9%.

Movers

Wind and solar (utility and rooftop) and batteries pushed out brown coal, gas and hydro in the NEM; solar and batteries pushed out gas in the SWIS.
*Source: onlyfacts.io*

In the NEM, the biggest mover relative to Spring 2024 was wind generation, up 23%, followed by utility solar, up 16%, and rooftop solar, up 10%. Brown coal and hydro both retreated 12%, and gas was down 8%.

Between Spring 2024 and this Spring, the giant (733MW) Golden Plains wind farm west of Melbourne, 450MW Clarke Creek Wind Farm in central Queensland, 387MW Aldoga Solar Farm northwest of Gladstone, and 202MW Stubbo Solar Farm north of Mudgee came online in the NEM, among 28 projects totalling 4.7GW. The 923MW Macintyre Wind Farm is in the process of being commissioned.

In the SWIS, utility solar soared by 136%, rooftop solar was up 6.8% and wind barely increased (1.3%). Gas — the west’s main product — shrank 20% while black coal increased 16%. The 128MW Cunderdin Solar-Battery hybrid project was the main addition to the grid, along with more than 500MW of big batteries (Kwinana and Collie).

De-tensifying

Increasing renewables and batteries in the grid mix lowers emissions intensity.
*Source: onlyfacts.io*

Welcome shifts like these inevitably mean falling emissions intensity from electricity generation. In the NEM, emissions intensity fell below 500 kg/MWh for the first time, down 7% from the same period last year to 475 kg/MWh.

In the SWIS, which generally has lower emissions intensity with more gas and less coal in its grid mix than the NEM, emissions intensity fell to 6% to 370 kg/MWh.

These are likely record seasonal lows for Australia’s largest grids as Spring — with its mild temperatures, healthy sunshine and high winds — typically has the lowest emissions of any season.

Shakers

The sharp retreat of coal, gas and even clean hydro in the NEM suggests a rapidly expanding fleet of batteries is playing a larger role in day-to-day firming as well as grid stability services (for which they’ve long been known).

The contribution of grid-scale batteries to the NEM jumped 168% — more than two-and-a-half times — to just under 500 gigawatt hours this Spring compared to last Spring. Efficiency — discharge into grid relative to charge — was 80%.

SWIS batteries more than tripled their output to 191GWh, with an efficiency of 86%. Again, with gas in sharp retreat (hydro in the SWIS is immaterial; coal’s surge is the outlier), batteries played a much larger role in firming renewables.

Grid-scale batteries push out traditional firming sources such as gas peakers and hydro, and wholesale prices are lower in Spring. *Source: onlyfacts.io*

With the lowest cost forms of generation surging and higher cost generation fossil fuels generally retreating in benign climatic conditions, wholesale NEM prices were lower in most states compared to Spring last year.

The exception was Victoria where Spring prices increased, but were still the second lowest at $54.90/MWh. The lowest priced state was Tasmania, at $33/MWh, while NSW had the highest prices ($87.10/MWh).

Long haul

All this is obviously good news for the transition. But it doesn’t tell us how the evolving grid will fare when the mercury soars and the wind drops during summer evenings when split system air conditioners are going flat out, or during a wind, solar and possibly hydro drought during a late Autumn/early Winter freeze when the ACs are running hard in reverse.

Neither is it enough to achieve national climate goals of 82% renewables in the grid by 2030, and emissions cuts of 62%-70% by 2035.

The Clean Energy Regulator says “close to 7GW” of combined utility-scale renewables and rooftop solar could be added to the grid by the end of this year.

But we need more like 7GW of utility-scale wind and solar each year — plus the usual near 3GW of rooftop solar — to get near the target, though the wildly successful home battery scheme will help.

The Climate Change Authority in its annual report said emissions cuts must more than double to hit the lower 2035 target, and triple to hit the top of the range.

What it does confirm is that adding more and more wind and solar generation and battery storage can push out fossil fuels, cut emissions and lower wholesale prices. But it must be done strategically, acknowledging the need for grid stability and gas peaking reserves for the most challenging summer heat waves and winter doldrums.