The smelter, the state's largest energy consumer, announced in August that it was aiming to switch to a predominantly renewable power supply in 2029 in a move to dramatically reduce its carbon footprint.

Rio Tinto, a joint venture owner of Tomago, announced on Wednesday that it would spend $7.5 billion to reduce carbon emissions by 50 per cent by 2030, a reduction three times greater than its previous target.

"(The Rio Tinto target) is absolutely consistent with the renewable objective we announced a few months ago; I'm a perpetual optimist, I think we will get there," Tomago Aluminium chief executive Matt Howell said.

Mr Howell stressed that firming capacity to stabilise the intermittency of renewables was essential to allow Tomago to achieve its renewable energy objective.

Snowy Hydro's Hunter Power Project will be among the sources of firmed energy.

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Rio chief executive Jakob Stausholm said the world was "much more aligned than ever before" on the need to tackle climate change.

"We have a clear pathway to decarbonise our business and are actively developing technologies that will enable our customers and our customers' customers to decarbonise," he said.

"We are able to do this while continuing to provide attractive returns to our shareholders in line with our policy because we have a strong balance sheet and world-class assets that deliver strong free cash flows through the cycle."

Hunter Jobs Alliance spokesman Warrick Jordan said the Rio Tinto's commitment to transitioning to renewable energy would put it in the box seat to meet the global demand for sustainable aluminium."

"Tomago have led with their recent commitment to move to renewables by 2029. Now Rio has backed this by setting their own emissions reductions targets and putting down large amounts of capital to make it happen. This is a big vote of confidence in the future of Hunter manufacturing."

"It's a huge opportunity to lock in thousands of local jobs for decades to come, but moving Tomago to renewables won't be a walk in the park and seven or eight years could disappear quickly unless the right plan is laid out soon. The NSW and Australian Government need to actively support laying out the roadmap and getting the very large amounts of renewables and firming required underway. It's a direct benefit to the local economy and local jobs. Government should play their part by investing in this critical jobs and environment outcome."

"This is a big deal for the future of the Hunter economy. It's important that there is clear communication with the workforce and community about how this opportunity gets realised, so people can understand what the plan is and get behind it"

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