South Australians and Victorians face the risk of four-hour blackouts over summer unless governments follow through on plans for new battery storage and diesel generators.
The Australian Energy Market Operator released its annual stocktake of electricity supplies on Tuesday, showing there's a heightened risk of a shortfall over the next decade if nothing is done.
The risk is highest in Victoria and South Australia, and beyond this summer in NSW and Victoria, after the Liddell power station closure planned for 2022.
"The power system does not have the reserves it once had," AEMO chief executive Audrey Zibelman said.
To balance peak summer demand in real time, targeted actions to provide additional firming capability was necessary to reduce heightened supply risks.
However, the report says SA government plans - including construction of a new battery and diesel generation - plus AEMO measures, do address the risks in that state.
The long-term projections don't take into account a range of recently announced storage and renewable generation projects, including the Snowy Hydro 2.0 plan Prime Minister Malcolm Turnbull has championed.
Mr Turnbull seized on the report to highlight the vulnerability of the nation's electricity supply, but said measures were in place to cover the immediate gap.
The prime minister also revealed he and Energy Minister Josh Frydenberg were in talks with AGL about keeping open the Liddell power station in NSW at least five years beyond 2022, when it will be 50 years old.
AGL wants to close all its coal-fired power stations by 2050, starting with Liddell in the NSW Hunter Valley, and in August ruled out extending its life.
Meanwhile, Labor has offered to work with the government for a "constructive compromise" on energy policy so something can actually be done to drive down power prices.
But the Greens are angry the two major parties may do a deal that includes subsidies for coal.
Mr Turnbull has set a deadline of developing a clean energy target - as recommended by Chief Scientist Alan Finkel - before Christmas.
Opposition Leader Bill Shorten called on the government to just get on with its job.
"The number one problem contributing to energy prices in this country, out-of-control energy prices, is the absence of proper national policy," he told reporters in Canberra.
The Greens want to work with Labor to set up a different mechanism for managing pollution and investment in the energy sector - an emissions intensity scheme - and is disappointed the opposition appears to prefer working with the government.
