The plan will also rely on "a lot of gas" and upfront costs, Nationals Leader David Littleproud conceded.
Opposition Leader Peter Dutton has pledged to build the nuclear reactors across five states on the sites of coal-fired power stations if the coalition wins government at the next election.
The costs and details of the plans remain scant, prompting concerns about safety in regional areas where the reactors are due to be built and the drawn-out 2035 completion date for construction of the first facility.
The Smart Energy Council has lashed Opposition Leader Peter Dutton's nuclear proposal. (Bianca De Marchi/AAP PHOTOS)
Using data from the CSIRO's latest GenCost report and the Australian Energy Market Operator's Integrated System Plan, the Smart Energy Council estimated the cost to taxpayers to be at least $116 billion.
The cost is the same as delivering 82 per cent renewables by 2030, and an almost 100 per cent renewable energy mix by 2050, including the cost of building all of the enabling transmission infrastructure, the council said.
Under the operator's forecast, the total expenditure required to fund all generation, storage, firming and transmission infrastructure was found to have a 2024-dollar value of $121 billion, to be invested gradually out to 2050.
The bulk of the $121 billion would be invested by the private sector between now and 2050 to deliver about 300 gigawatts of capacity by 2050.
These figures compare to just 11 gigawatts of nuclear capacity funded by the taxpayer in the opposition's proposal, the council said.
Smart Energy Council chief executive John Grimes said Mr Dutton's nuclear proposal would deliver "at best" 3.7 per cent of the energy required at the same cost as the government's current strategy.
Smart Energy Council chief John Grimes says the coalition must detail costings for its nuclear plan. (Lukas Coch/AAP PHOTOS)
"In reality, current cost overruns happening right now in the UK could mean a $600 billion bill to Australian taxpayers, whilst delivering a small proportion of the energy that is actually required," he said.
Nuclear had no place in a country with cheap, reliable energy powered by the sun and wind and backed up by renewable energy storage, Mr Grimes said.
"The most optimistic assessment of Peter Dutton's nuclear proposal indicates it is a pale shadow of the reliable renewables plan outlined and costed by the Australian Energy Market Operator," he said.
The council has called on the opposition to release its analysis of the costings and generation capacity from the seven proposed nuclear reactor sites.
"They need to explain how their forecasts contradict the experts at the CSIRO and AEMO," Mr Grimes said.
"It is extraordinary that the details are being hidden from the Australian public."
Opposition energy spokesman Ted O'Brien said Australians "won't have long to wait" until they understand how much energy nuclear power will contribute to the nation's energy mix.
"Our focus is on the Australian people who want to save money," he told Insiders on Sunday.
Mr Littleproud said there would be an upfront cost but he assured Australians the costings would be delivered "well before the election".
"Nuclear energy will firm up and transition some of our coal-fired power stations with gas - and you're going to need a lot of gas - as the government will with an all-renewables approach" he told Sky News.
"There's a big difference between the upfront costs and the dividends that it'll pay back over the life of the assets."
This comes after Mr Dutton took a swipe at Prime Minister Anthony Albanese during a speech on the nuclear plan, calling him a "child in a man's body".
Environment Minister Tanya Plibersek urged the opposition to bring the discussion back to the details of their plan.
"He's calling for mature debate and he's gone straight to the personal attacks," she said.
"I think that speaks for itself."
