Rio Tinto Kennecott transitioning all heavy machinery to renewable diesel

Over the past decade, Rio Tinto Kennecott — home to the world's deepest open pit mine — has taken massive strides in reducing its carbon footprint.

Kennecott in 2019 shut down its last coal-fired power plant, eliminating 6,000 tons of pollutants from the Salt Lake Valley airshed.

To continue this momentum, the mining giant on Tuesday announced a full transition from conventional to renewable diesel for the mine's entire fleet of 97 haul trucks and heavy machinery equipment at the mine, concentrator, smelter, refinery and tailings.

After a seven-month trial period, the complete transition is expected to reduce the mine's emissions by 450,000 tonnes — the same reduction as eliminating the annual emissions of over 100,000 cars.

The switch also reduces the PM2.5 (particulate matter less than 2.5 microns) emissions from the tailpipes of the company's haul truck fleet by 40%, a reduction equivalent to eliminating approximately 2.3 billion miles of light vehicle travel annually.

With the retirement of the coal-fired power plant and the latest transition to renewable diesel — along with installing a 5-megawatt solar farm and deploying electric vehicles for underground copper mining — Kennecott has reduced its overall carbon footprint by more than 80% compared to 2018 levels.

"That's a huge change," said Clayton Walker, chief operating officer of Rio Tinto Copper. "I think this is just another step in showing our commitment into making the environment the best that we can and trying to show how to do that in a responsible manner."

During the trial run of the renewable diesel program, the company compared haul trucks' acceleration, cycle time, fuel usage and engine inspection reports, finding renewable diesel to be a good replacement for conventional diesel.

The haul trucks aren't small, either, often weighing over a million pounds and toting 1,400-gallon fuel tanks.

"It's like moving a house," said Aaron Clement, craftsman and haul truck driver at Kennecott. "You don't have a whole lot of visibility. It's an experience for sure."

Clement said the switch to renewable diesel hasn't come with any performance drawbacks as far as operating the haul trucks.

"It's pretty identical. Maybe a little less smoking," Clement said.

Utah Gov. Spencer Cox was present during the announcement, saying his trips to Kennecott usually coincide with big announcements like the one made Tuesday.

"This is a great model. Companies are doing things like this all over the valley and all over the state," Cox said. "We'll never be able to regulate our way out of some of the (environmental) problems we're having, but we certainly can innovate our way out and these are the types of innovations that make sense. It saves money, and it improves the environment."

He said Utahns can expect more announcements, ahead of the upcoming legislative session, about how to produce more energy while also "treating the environment in a way that is good for everybody who lives here."

Renewable diesel is harnessed from soybean, animal fats and cooking oil, making it much cleaner than traditional fuel sources. It's also sourced from within the U.S., something Walker said was important to the company.

"Locally, there was no source of renewable diesel here, so our thing was, 'How do we source it?'" Walker said.

Steven Ledbetter, executive vice president of HF Sinclair — the company supplying Kennecott with renewable diesel — said it's being transported via a pipeline, further reducing emissions that would come with transporting it by trucks hauling the fuel.

With more emissions reductions on the horizon, Rio Tinto Kennecott aims to be net zero by 2050.