Kennecott's fleet of 90 haul trucks and all heavy machinery will begin to transition to renewable diesel in the first quarter of the new year, along with consumption from the concentrator, smelter and refinery, it said.
The global miner added the transition will reduce Kennecott's carbon emissions by about 495,000 tons of carbon dioxide equivalent per annum.
"Transitioning Kennecott completely to renewable diesel builds on a suite of decarbonisation initiatives that have reduced carbon emissions from the operation by 65% since 2019," said Clayton Walker, Rio Tinto's copper chief operating officer.
Rio is targeting reductions in carbon emissions of 50% by 2030 and net zero by 2050.
In May, it had completed the full transition of its heavy machinery from fossil diesel to renewable diesel at the Borax mine in California.