Mining company Rio Tinto will buy solar power and battery storage capacity for its Gladstone aluminium operations in a deal environmentalists have hailed as a “major step” forward.

The company has signed 20-year agreements with Edify Energy to buy 90% of the power and battery storage capacity generated by the Smoky Creek and Guthrie’s Gap solar stations, located in central Queensland, Rio Tinto said.

Kellie Parker, chief executive of Rio Tinto, said the agreements would provide “affordable, reliable and low carbon energy for decades to come”, as traditional energy sources became more expensive.

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Together with existing wind and solar agreements, renewable energy was now expected to meet 80% of the Boyne smelter’s electricity needs, the company said, reducing the facility’s direct emissions by 70%, equivalent to 5.6m tonnes of carbon dioxide a year.

Construction on the projects, located 75km south of Rockhampton, was expected to begin in late 2025 and completed in 2028, delivering 600MW of solar power and 600MW/2,400MWh of battery storage.

Rio Tinto said it would continue to investigate further renewable energy investments to support its Gladstone operations, which employs more than 3,000 workers, a third of which were based at the Boyne aluminium smelter.

The Edify Energy chief executive, John Cole, said the collaboration was an important commitment towards a sustainable future for the country’s industrial sector.

‘Right direction’

Dr Tessa Leach, a senior industry project manager at ClimateWorks Centre and lead author of a report on decarbonising Gladstone’s heavy industry, described the announcement as a “major step in the right direction”.

Low-cost renewable energy would enable the region’s energy-intensive industries to remain competitive, by making the most of its natural renewable energy advantages, she said.

To reach its potential as a hub for clean industry, Gladstone would need access to new wind, solar and energy storage projects at the scale required to provide for electricity, heat and alternative feedstock, she said.

John Grimes, the Smart Energy Council chief executive, said Rio Tinto’s decision showed how quickly the world’s biggest mining companies were moving towards renewable energy.

It also reflected increasing global demand for decarbonised aluminium, iron and other metals, he said.

“Australia’s most energy intensive sectors are backing renewables because they are more reliable, cheaper and cleaner than fossil fuel alternatives,” he said.