BINGHAM CANYON – Over the past decade, Rio Tinto Kennecott – home to the deepest open-pit mine in the world – has made tremendous progress in reducing its carbon footprint.

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

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

After a seven-month trial period, the full transition is expected to reduce the mine’s emissions by 450,000 tonnes – the same reduction as eliminating annual emissions from more than 100,000 cars.

The move also reduces PM2.5 (particulate matter smaller than 2.5 microns) emissions from the tailpipes of the company’s truck fleet by 40%, a reduction equivalent to eliminating approximately 4.7 billion kilometers of light vehicle travel per year.

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

“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 to making the environment the best it can be and showing how we can do that responsibly.”

During the pilot period of the renewable diesel program, the company compared the acceleration, cycle time, fuel consumption and engine inspection reports of trucks, finding that renewable diesel is a good replacement for conventional diesel.

The trucks aren’t small either: they often weigh more than a million pounds and have a 4,000-gallon fuel tank.

“It’s like moving a house,” said Aaron Clement, a Kennecott tradesman and truck driver. “You don’t have a lot of visibility. It’s definitely an experience.”

Clement said the switch to renewable diesel will not come with any performance disadvantages in terms of operating the trucks.

‘It’s almost identical. Maybe smoke a little less,” Clement said.

Utah Gov. Spencer Cox was present for the announcement and said his trips to Kennecott usually coincide with big announcements like Tuesday’s.

“This is a great model. Companies are doing things like this all over the valley and across the state,” Cox said. “We will never be able to find a solution to some of the (environmental) problems we have, but we can certainly innovate our way and these types of innovations make sense. It saves money, and it improves the environment.”

He said Utahns can expect more announcements ahead of the upcoming legislative session on how to produce more energy while “treating the environment in a way that is good for everyone who lives here.”

Renewable diesel is extracted from soybeans, animal fats and cooking oil, making it much cleaner than traditional fuel sources. It also comes from the US, something Walker said was important to the company.

“Locally, there wasn’t a source of renewable diesel here, so our thing was, ‘How do we get it?’” Walker said.

Steven Ledbetter, executive vice president of HF Sinclair – the company that supplies Kennecott with renewable diesel – said the fuel is transported via pipeline, further reducing the emissions associated with transporting it by trucks carrying the fuel.

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