The mining union says hundreds of workers at Myuna and Mandalong collieries face an uncertain future despite a short-term deal struck between Origin Energy and Centennial to supply coal to Eraring Power Station.
Eraring's owner and Centennial Coal reached a deal on Thursday to extend their existing supply contract for six months beyond its expiry date this month.
Mining and Energy Union president Robin Williams said the MEU welcomed the announcement but workers would find themselves in the same position in six months' time.
"Workers are hopeful that a longer-term arrangement can be reached considering that Origin Energy have the security to operate for the next three years, with the NSW government underwriting profits," Mr Williams said.
"We believe that the security afforded to Origin Energy should be shared with the coal miners whose livelihoods depend on supplying coal to the power station."
The short-term agreement leaves Origin open to continue to negotiate with Centennial on a longer-term deal or chase coal supplies from other mining companies beyond this year.
The new deal is a brief reprieve for Myuna, which exists only to provide coal to Eraring.
Mandalong sells about half its output to Eraring, which is the nation's largest coal-fired power station.
The NSW government announced last month that it would pay Origin Energy up to $450 million to underwrite Eraring's operation for two years beyond its planned August 2025 closure.
The agreement with the government gives Origin the option of opting in to the underwriting deal for one year starting July 1, 2025, and for another year starting July 1, 2026.
The agreement sets Origin the "target" of locking in a coal supply deal by December to power two of Eraring's four generators throughout the year starting July 1, 2025.
Minister for Natural Resources Courtney Houssos said the government's agreement with Origin "imposes an obligation on Origin to secure sufficient coal supply to power Eraring for its continued operation".
Eraring, which supplies about a quarter of the state's power, must close by April 30, 2029, under its deal with the government.
Collieries Staff and Officials Association lead organiser Belinda Giblin said Origin should agree to take coal from both mines for the life of the power station.
"This would bolster Origin Energy's social licence and line up with its rhetoric on just transition," she said.
She said 350 people working at Myuna would have been jobless from June 30 had no deal been reached.
"Our members have kept the lights on in NSW for more than 40 years by supplying Eraring with fuel," Ms Giblin said.
"Mine workers are relieved that commonsense and fairness have prevailed over attempts to extract momentary profits at the expense of local communities."
The CSOA urged "greater certainty for communities, and greater consideration of supply-chain impacts by asset owners and policymakers, in energy transition planning".
The deal between Origin and Centennial comes after weeks of at-times testy negotiations between the two parties.
Origin implied in public statements that Centennial was asking too much for its coal, while Centennial countered by saying Origin was risking "1000 direct jobs", 1200 extra coal train movements through Newcastle each year and $360 million in royalties if it did not agree to a deal.
Origin said on Thursday that it was "pleased to have secured this coal on competitive terms, which helps underpin secure and affordable electricity supply for NSW".
"We intend to maintain an ongoing dialogue with Centennial Coal regarding a possible extension to this agreement in future," the company said.
"More broadly, Origin is committed to continuing to actively engage across Eraring's supplier base on their plans to support workers and the community in the years ahead as we transition towards the eventual retirement of Eraring Power Station."
Centennial described Thursday's deal as an "important first step to ensure job security for our workforce and the state's energy security".
"The agreement comes with an expectation that we will work together with Origin on a longer-term coal supply contract that will underpin the lifespan of Eraring Power Station," Centennial said in a statement.
