The Energy’s data newsletter, delivered every Wednesday, quickly became an audience favourite shortly after our launch this year. We’re grateful for the people who appreciate a good chart! Here are our favourites, which collectively tell the story of the energy transition in 2025.

1. Batteries changing the grid

When Ryan Wavish, general manager innovation at Engie Retail, and Kirsty Gowans, head of electricity at DCEEW both suggested the record-busting uptake of the Cheaper Home Batteries Program was having an impact on the duck curve, Ben Potter did some digging.

Data from UNSW senior research associate Dylan McConnell showed it’s too early to conclude that batteries have materially moved the duck curve, but watch this space, as there is mounting evidence that the duck is at least slimming.

Batteries, and this includes utility-scale, appear to be pushing the price trough back later in the day and reducing the extent of negative prices.

2. The heat effect

With Australia staring down another summer of heatwaves, this chart from the International Energy Agency serves as a reminder of the carbon-emitting fuels that step in to meet extra demand. It shows that temperature effects contributed around 20% to the increase in electricity and natural gas demand and drove the entire increase in coal demand on the back of heatwaves in China, India and the US in 2024.

As demand for energy-hungry cooling rises, residential and commercial rooftop solar and batteries along with energy efficiency can also do the job, but only if the incentives are right.

3. Shifting data centre forecasts

This year saw the market operator split data centres out from other large industrial loads in the reports that help inform the Integrated System Plan.

AEMO’s Step Change scenario now predicts data centre energy consumption will increase by an average of 25% per year, reaching around 6% of the NEM by 2029-30, double what it had previously been forecasting.

But behind the new numbers are some highly variable assumptions - the biggest one being whether Australia can capture the AI market, delivering on Scott Farquar’s vision for Australia to “export megawatts as megabytes”.

This chart from AEMO-adviser Oxford Economics Australia shows just what that scenario might mean for energy consumption.

4. Curtailment goldilocks

Curtailment hit new records in 2025, with up to 30% of total solar generation and around 15% of wind generation curtailed during the peak Spring season.

Curtailment is a feature of a renewable energy system, but we are currently seeing curtailment at levels not previously anticipated until FY2030, when there is expected to be much more renewables in the system.

As Dylan McConnell explains, greater coal flexibility, getting transmission projects moving and addressing network congestion are all required to shift the curtailment dial to where it should be.

5. Costly coal

Opponents of renewable energy who point to the very real cost issues with wind, hydro and transmission often fail to consider the alternative.

The futility of wishing coal generation back into the grid mix was starkly illustrated by this chart from December’s GenCost report, which showed the capital cost component of generation over the eight years since CSIRO began compiling GenCost.

6. Gas gaps

“Gas the transition fuel” became the talking point of politicians in 2025, culminating in this week’s announcement of a domestic gas reservation plan that would require exporters to reserve up to 25% of gas production for the local market.

Energy Edge’s Gas Market Analysis prepared for LNG exporter APLNG identified a sweet spot of an extra 30 petajoules a year to be supplied by the three Queensland producers to the local market. This equates to about 80 terajoules a day, or about 6% of East Coast domestic consumption.

Managing director Josh Stabler says this amount would provide the optimal combination of maximum price reductions and minimum deterrence of investment in new production.

7. Energy efficiency beyond 'embroidery'

In 2025, Australia reaffirmed a COP28 pledge to double the average annual rate of energy efficiency improvements every year until 2030.

But in the same year, Energy Minister Chris Bowen called efficiency “an important part of the embroidery of decarbonisation to complement the transition to renewables”, with the government’s focus remaining steadfastly on reforms needed to meet renewable energy targets.

Boosting productivity is a major agenda item in the Albanese government’s second term, and this chart serves as a reminder of what energy efficiency can do for GDP.

8. Solar sharer and other pricing snares

Significant changes to electricity pricing are headed our way in the year ahead.

Topping the list will be the delivery of the government’s “Solar Sharer” offer, which caught retailers off guard when announced in October, and will likely be the biggest experiment the sector has seen on incentivising household users of energy to change their behaviour.

This chart shows the impact time-of-use tariffs have on changing consumer energy use, hinting at the challenge policymakers have often faced in successfully nudging consumer behaviour to benefit the system.

9. China's total domination

This year the International Energy Agency warned China's dominance in refining critical minerals was creating major vulnerabilities and bottlenecks for the global clean energy transition.

European and US efforts to 'reshore' manufacturing of solar panels, batteries, electric vehicles and other clean energy goods are of recent origin relative to China’s long-term campaign to dominate these industries. So far they have yielded negligible results.

10. A grid milestone

Amid the negative noise and challenges of the transition, it was easy to overlook the major milestone of 2025 - renewable energy reaching parity with fossil fuels in the NEM.

This inevitably meant 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.