Renewables look likely to be the cheapest energy source in Australia again next year, according to a draft of the new Gencost report from the Australian Energy Market Operator (AEMO) and the CSIRO.

The report has been issued as political debate around the costs of nuclear energy heats up.

The draft 2024-25 GenCost report finds that solar and wind remain the cheapest energy source, even when battery storage is taken into account.

Large-scale solar PV has fallen in price by 8% over the last year, while batteries have dropped in price by 20%.

The cost of onshore wind has risen by 2% because of equipment and installation costs, while gas turbines and black coal have gone up 11% and 4%, respectively.

 Nuclear power, meanwhile, has “no unique cost advantage” – even with new considerations accounting for its long life.

It’s the 7th year in a row that the report has found renewable technologies to be the cheapest new electricity source.

The draft report is open for public consultation until next February.

“Collaboration and transparency are central to this process, and the feedback we receive plays a vital role in ensuring our data and projections are relevant and impactful,” says Dr Dietmar Tourbier, director of energy at CSIRO.

Following criticism about last year’s report, CSIRO and AEMO have provided “additional evidence and analysis” on nuclear power.

This includes taking nuclear power’s longer lifespan into account – 60 years, rather than the 30 years GenCost uses as an industry default.

“Similar cost savings can be achieved with shorter-lived technologies, including renewables, even when accounting for the need to build them twice,” says lead author Paul Graham, chief energy economist at CSIRO.

“The lack of an economic advantage is due to the substantial nuclear re-investment costs required to achieve long operational life.”

The report defends its use of other nuclear numbers that have come under fire: capacity factor, which represents the amount of time a plant is making electricity, and lead time for building new nuclear power stations.

For instance, the USA has a nuclear capacity factor of 93%, but the report points out that globally, it’s lower at 80%, and black coal in Australia only manages 59%.

“On this basis a single point estimate of 93% does not adequately capture the plausible range achievable in Australia,” reads the executive summary. The report uses a 53%-89% range instead.

It says lead time to build a nuclear plant remains at least 15 years, rather than the 10-15 years proposed by the International Atomic Energy Agency in 2015.

“Many stakeholders have agreed with the GenCost estimate of at least 15 years lead time for nuclear generation,” reads the executive summary, pointing out that median construction time has increased since the 2015 estimate, and that democratic countries tend to bring the average down.

In Finland and the USA, for instance, nuclear power plants take an average of 17 and 21 years to construct, respectively.

The final edition of the report will be released in mid-2025.