Miner Rio Tinto has completed the transition from conventional to renewable diesel for all heavy mining equipment at its Kennecott copper mine in Utah, giving the mine one of the lowest carbon footprints of any copper producer in the US.

Kennecott’s fleet of 97 haul trucks and heavy machinery equipment at the mine, concentrator, smelter, refinery and tailings are now all fuelled by renewable diesel sourced in the US. This is expected to reduce the mine’s Scope 1 emissions by 450 000 t, equal to eliminating the yearly emissions of 107 000 cars.

In addition, the switch to renewable diesel reduces PM2.5 (particulate matter less than 2.5 microns) emissions at the tailpipes of the haul truck fleet by 40%, a reduction equivalent to about 2.3-billion miles of light vehicle travel a year.

"The transition to renewable diesel is a significant step toward our decarbonisation goals at Kennecott where we have now reduced emissions by 80%, thanks to a range of initiatives in recent years," said Rio Tinto Copper COO Clayton Walker in a statement.

In 2023, Kennecott conducted an initial trial of renewable diesel, which compared two trucks using regular diesel against two using renewable diesel. Officials measured the trucks’ acceleration, cycle time, fuel usage, and engine inspection reports. The renewable diesel was trialled successfully, complementing similar test findings from Rio Tinto’s Boron mine, in California. 

Combined with Rio Tinto's Boron mine - which completed the full transition of its heavy machinery from fossil diesel to renewable diesel in May 2023 – renewable diesel use at Kennecott replaces 11% of Rio Tinto's global fossil diesel consumption with renewable diesel.

Kennecott already has one of the lowest carbon footprints among US copper producers thanks to recent initiatives such as the closure of a coal-fired power plant, installation of a 5-MW solar farm, deployment of battery electric vehicles underground, and the transition to renewable diesel. The operation’s overall carbon footprint has now been reduced by more than 80% from 2018 levels. 

Kennecott’s transition to renewable fuel will also make low-carbon fuel more accessible in the state of Utah. In partnership with Kennecott, HF Sinclair is dedicating two tanks to renewable diesel for the mine with each having tank capacity of 18 000 barrels.