In short:

The Coalition has presented modelling that suggests its nuclear policy would cost over $300 billion, which it argues is cheaper than Labor's proposal.

The policy would see the first nuclear power plant operational by 2036, with 14GW of capacity by 2050.

What's next?

Labor has dismissed the policy as "a fantasy," citing this week's report by CSIRO and the energy market operator which found nuclear was more expensive than renewables.

Peter Dutton's nuclear power proposal relies on a smaller economy and higher carbon emissions, and would cost more than $300 billion, according to his long-awaited costing.

The proposal would still see more than half of Australia's power come from renewables, but coal would be kept for longer to fill the gap before nuclear plants arrive in 12 years' time at the earliest.

The costing, prepared by Frontier Economics, found a system with nuclear would be cheaper over a 25-year period than a system without it.

That contradicts the finding of the CSIRO and the Australian Energy Market Operator (AEMO) that nuclear is twice as expensive than renewables.

The lower result is partly because the Coalition's costing "spreads out" the cost of the nuclear plants over their 50-year life span, an accounting measure which means the bulk of the costs are recorded outside the 25-year costing window.

The opposition leader said his plan was $263 billion cheaper than Labor's proposal, citing Frontier modelling.

But that claim relies on Frontier's $600 billion figure for Labor's policy which Labor disputes, and it also does not compare like with like. Instead, it chooses a scenario for Labor where energy needs are almost 50 per cent higher than under the Coalition, shaving $115 billion off the Coalition cost.

That implies broader climate goals like electric vehicle adoption and electric heating are not adopted, which makes the Coalition's figure appear cheaper because it excludes the petrol and gas costs that would result.

While the Coalition remains committed to reaching net zero emissions in 2050, Mr Dutton's chosen scenario would mean higher emissions between now and 2050, almost certainly jeopardising Australia's contribution to the global goal of limiting climate change to 2 degrees Celsius.

Mr Dutton said his plan would "underpin the economic success of our country for the next century … This will make electricity reliable, it will make it more consistent, cheaper for Australians, and it will help us decarbonise as a trading economy as we must".

The Coalition's energy spokesperson Ted O'Brien said the plan would see a smoother transition.

"Our plan responsibly integrates renewables … At the same time, zero-emissions nuclear energy and gas provide the reliability that Labor's plan fails to deliver."

Labor says modelling has 'three fatal errors'

Shortly after the Coalition released its modelling, Energy Minister Chris Bowen held a media conference to dismiss it as "riddled with fundamental errors".

In particular, he pointed to "three fatal errors": the assumption that Australia will need less energy in 2050, that there will be savings from fewer transmission lines, and that an ongoing cost of $30 a megawatt hour will continue with nuclear.

"AEMO and the CSIRO say nuclear is expensive. Peter Dutton and Ted O'Brien say it's cheap. I know who I believe," he said.

Mr Bowen also took aim at the Coalition for the lack of modelling on whether their nuclear plan would result in lower energy bills. 

"After months of talking about what nuclear would mean for energy bills, they couldn't even put a price on the impact of their plan on the average bills of Australians," he said.

Prime Minister Anthony Albanese described the "nightmare policy" as "a plan for the 2040s". 

"In the meantime, I'm not quite sure what [Peter Dutton] thinks will happen with energy security."

The Climate Council also dismissed the Coalition's modelling as "dodgy accounting".

“The federal Coalition’s nuclear scheme would send our kids’ future up in smoke. Waiting up to 20 years for nuclear reactors means burning coal and fossil gas longer," Climate Council chief executive Amanda McKenzie said in a statement.