Haul truck at Kennecott, Bingham Canyon Mine

Fuelling our trucks with renewable diesel

Diesel made from renewable raw materials – like waste from the food industry – is helping us reduce emissions

Last updated: 11 April 2023


Diesel is a common fuel in the mining industry, because diesel engines are powerful enough to move trucks that can be the size of a two-storey house on wheels, more than 7 metres tall, and carry hundreds of tonnes in every load.

But conventional diesel engines are a major source of greenhouse gas emissions, with diesel for our mobile fleet and rail representing approximately 13% of greenhouse gas emissions across our operations. Despite making advances globally in electrifying our mining fleets, we still rely on emissions-heavy fuel for transport, haulage and logistics.

At our Boron operation in California in the US, we’ve been trialling a new kind of diesel that’s proven a reliable substitute for conventional diesel. And it’s not just helping us to reduce greenhouse gas emissions from our diesel-powered haul truck fleet – it's also made from renewable materials.

Diesel truck

What is renewable diesel?

Renewable diesel is chemically identical to conventional diesel, but it’s created from renewable raw materials instead of crude oil. Because it’s so similar, we don’t need to modify our existing diesel engines – our existing fleet of diesel trucks, trains and mobile equipment can switch straight to using it. Renewable diesel generates far lower greenhouse gas emissions, and doesn’t have a shelf life, meaning its storage and distribution is far easier. And it meets the ASTM D975 specification for petroleum in the United States and EN 15940 in Europe.

Trialling a renewable fuel source

At Boron, we used Neste MY Renewable Diesel™, a hydrotreated vegetable oil made entirely from sustainably sourced renewable raw materials like used cooking oil and animal fat from the food industry. When used in its purest form, Neste MY Renewable Diesel™ can deliver up to 75% less greenhouse gas emissions than conventional diesel.1

The seven-month trial, started in 2022 in partnership with Neste and Rolls-Royce, showed trucks running on renewable diesel are as consistently reliable and efficient as trucks running on petroleum-based diesel, proving that it’s a viable alternative.

We’re now working with the Environmental Protection Agency, the state of California, and engine manufacturers to transition our whole heavy machinery fleet at Boron to renewable diesel by 2024.

We predict this will reduce our carbon emissions by 45,000 tonnes per year – equivalent to the emissions from more than 9,600 cars.2

“It is very exciting to be the first Rio Tinto operation to prove a concept that will continue to be used many years into the future,” said Donald, Acting Mine Manager, Boron.

Renewable diesel haul truck

Translating renewable diesel to other places

Given the success of the Boron trial, we’re now conducting a second trial at our Kennecott copper operation in Utah.

We've partnered with Cummins to trial renewable diesel at Bingham Canyon to see if it’s reliable as an alternative fuel for different equipment in a different environment.

Over the seven-month trial, the team is testing acceleration, speed, cycle times, fuel usage, and engine inspection reports for two trucks running on renewable diesel versus two trucks running on conventional diesel, using the same methodology as the Boron team so they can compare the results.

“It is great seeing the trial launch at Kennecott, in the Salt Lake Valley where I live with my family, and knowing that Rio Tinto is committed to reducing its carbon footprint,” said Brian, Senior Engineer, Projects. “Many teams at Kennecott, and in the wider Rio Tinto, are involved in making this project a success, and so far the data is very promising.”

Diesel accounts for the largest portion of Kennecott’s greenhouse gas emissions, and renewable diesel could provide one component in the overall mix of solutions that will be needed for decarbonisation. Alongside this, Kennecott is also one of a number of our sites that are running a trial of battery electric vehicles, aiming to fully decarbonise our haul truck fleets over the longer term.

“The renewable diesel trials at our U.S. Borax and Kennecott operations could pave the way for Rio Tinto to be the first mining company in the US to operate a fully renewable fleet,” said Simon, Vice President, Global Procurement. “It’s a very exciting step towards reducing the carbon footprint of our US operations.”

1 Lifecycle greenhouse gas emission reductions compared to fossil diesel and based on current feedstock pathways. Calculation method complies with the LCFS CA-GREET 3.0.

2 Source: United States Environment Protection Agency Greenhouse Gas Equivalencies Calculator. 45,000 tonnes CO2e is equivalent to greenhouse gas emissions from 9,696 gasoline-powered passenger vehicles driven for one year.