Malcolm Turnbull will visit Victoria's coal mining region on Thursday as he continues his push to get AGL to sell a coal plant in NSW.
The prime minister is set to visit the Latrobe Valley, where AGL has its Loy Yang coal plant, and the site of Engie's recently-closed Hazelwood power station.
AGL Energy boss Andy Vesey has continued to resist pressure from the government to sell the Liddell power station in a bid to keep it open past 2022.
He said the decision to keep the aging plant was based on a rigorous process.
"Second guessing is not part of that because when we make that decision we have alignment, we have the underlining work to prove it and that is the only way you can deal with these things," Mr Vesey told the Inspiring Leadership Summit in Sydney on Wednesday.
"I think it was a big step for the company and we still all agree that it was the right step."
Treasurer Scott Morrison on Tuesday urged AGL to consider an offer from Alinta Energy to buy the Liddell power station, which is expected to close in 2022.
Mr Turnbull also wants Liddell to stay open until 2025, when Snowy Hydro 2.0 is online, to ensure there is no gap in power availability.
But in a blog posted on AGL's website on Thursday, the company argueed it would cost $920 million just to keep the plant open for five more years.
"We can't cut corners on maintenance or refurbishment because workers' safety comes first," AGL said.
The company also plans to refurbish the site after 2022 with gas, solar and wind alternatives as well as battery storage.
But Energy Minister Josh Frydenberg said AGL was yet to provide a financial commitment to all three stages.
"So you're asking the government to wait for a board decision down the track before we actually secure supply," he said.
"That is not something the government will do."
