A Morrison government-backed proposal which could extend the life of coal and gas plants will be "adamantly" opposed by the ACT at a crunch meeting on Friday.
ACT energy minister Shane Rattenbury will instead push for the energy incentives scheme to be overhauled so that it applied only to zero emissions technologies.
State and territory energy ministers will on Friday meet with their federal counterpart Angus Taylor to consider advice on sweeping reforms to the energy market beyond 2025.
The most controversial proposal put forward by the Energy Security Board is for a new "capacity mechanism", which would use incentives to retain existing power generation to help keep the system reliable and affordable amid the transition to renewables.
Mr Taylor has argued the intervention could help prevent dispatchable generators - including coal-fired power plants - from shutting down too quickly and sparking the price shocks which occurred after the closure of the Hazelwood plant in 2017.
The scheme has been dubbed "CoalKeeper" by its critics in the renewables sector, who say the mechanism would prop up unprofitable coal generators, increase prices and delay the clean energy transition.
It has also faced resistance from some states, with Victoria's energy and climate change minister, Lily D'Ambrosio, this week declaring the Andrews government wouldn't support a scheme which delayed the clean energy transition or locked-in "outdated" technology.
Mr Rattenbury, who is also ACT Greens leader, echoed those comments in a statement ahead of Friday's meeting.
He said he had written to all energy ministers with proposed changes to the scheme, including that it should only apply to renewables and wouldn't be used to prolong the life of existing generators.
"The ACT will adamantly oppose any proposed subsidies to extend the lives of polluting coal and gas-fired power stations," he said in the statement.
"It is vital that energy ministers are absolutely clear in their instructions to the ESB that we expect the market bodies to undertake any reform in a way that rapidly reduces emissions from Australias electricity sector.
"The current guidelines leave too much to chance we have to be definitive what future they are taking us towards.
"The target must be a 100 per cent renewable energy system so that we can address climate change and help achieve state and territory commitments of net zero emissions by 2050 at the latest."
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