Origin Energy and Centennial Coal are edging towards a supply deal for Eraring Power Station which could provide little job security for hundreds of miners.
Sources have told the Newcastle Herald the companies are close to signing a deal which would extend Myuna colliery's deal to supply coal to Eraring for another six to 12 months but exclude Mandalong, the other underground pit that helps feed Australia's largest coal-fired power plant.
Neither Origin nor Centennial would comment about their negotiations, but sources said the two parties had met again on Tuesday.
The NSW government announced last month that it would pay Origin Energy up to $450 million to keep Eraring open for two years beyond its planned August 2025 closure.
The Mining and Energy Union welcomed the agreement but said hundreds of miners at Myuna and Mandalong were still in the dark about the collieries' future.
Myuna supplies exclusively to Eraring, while Mandalong sells about half its output to the power station. Both mines send coal to Eraring via conveyor belts.
Eraring, which supplies about a quarter of the state's power, is due to close in two to four years.
A new short-term deal would give the Myuna pit and its several hundred workers a reprieve, but the mine likely will close when any agreement expires.
It is not clear where Origin would buy coal from for Eraring if the plant stayed open after a new deal with Myuna expired, but an Origin spokesperson said last month that "locking in higher-priced coal when there are cheaper options available from other domestic sources risks putting upwards pressure on wholesale electricity prices for NSW customers".
Centennial said last month that sourcing coal from somewhere else could put 1200 more coal train movements on rail lines through Newcastle.