Rio Tinto converts first open pit mine to renewable diesel - mtu engines power large vehicles

• Rio Tinto U.S. Borax becomes first open pit mine to switch to renewable diesel
• Rolls-Royce supports transformation with mtu engine tests
• mtu Series 4000 engines in dump trucks and wheel loaders show convincing performance with renewable diesel

Rio Tinto has completely switched heavy machinery at its Boron mine in California from fossil diesel to renewable diesel, or hydrotreated vegetable oil (HVO) making it the first open pit mine in the world to reach this milestone. Rolls-Royce is supporting the mining company in its endeavor and has been testing mtu engines on HVO in dump trucks and wheel loaders since 2022. During the 2,000 hours of operation to date, it has been demonstrated that the engines run on the renewable diesel deliver similar performance and reliability to fossil diesel. The switch to renewable diesel at the Boron mine is expected to reduce CO2 by up to 45,000 tonnes per year, equivalent to annual emissions from about 9,600 cars.

Close cooperation between Rio Tinto, Rolls-Royce and Neste led to success

Sinead Kaufman, Chief Executive Rio Tinto Minerals said: “We are proud that our U.S. Borax operations have become the first open pit mine to operate a fleet running entirely on renewable diesel. This is an excellent example of what happens when internal and external partners collaborate toward a carbon reduction goal. Support from the state of California has also been incredibly important, as without their vision, this would not have been possible.”  

Cobus van Schalkwyk, Director Global Mining at the business unit Power Systems of Rolls-Royce, explained: “The conversion of the first open pit mine to HVO is an important milestone. We are pleased to be part of the energy transition at the U.S. Borax mine and partner with Rio Tinto. With further sustainable offerings, such as reman or remotorization solutions for the vehicles or microgrids for energy supply, we are ready for the further future of the mines.”

Significant reduction in CO2, particulates and NOX with no change in performance

An initial trial to convert from fossil diesel to renewable diesel in a Borax dump truck was conducted by 2022 in collaboration with fuel manufacturer Neste and Rolls-Royce. Rio Tinto U.S. Borax used Neste MY Renewable DieselTM during the trial. Neste MY Renewable Diesel is made from sustainably sourced, 100 percent renewable raw materials such as waste cooking oil and animal fat waste and can reduce greenhouse gas emissions by up to 75 percent* over the lifecycle of the fuel compared to fossil diesel. The results of the trial showed that a dump truck powered by mtu engines running on renewable diesel had similar performance and reliability to dump trucks running on conventional diesel.

Drop-in fuel HVO requires no engine adjustments

Other benefits of renewable diesel include clean combustion with a reduction in particulate emissions of up to 40 percent in mobile applications and a reduction in nitrogen oxide emissions by an average of eight percent. HVO is a drop-in fuel, which means that the existing diesel plant infrastructure can be used unchanged for its use, and no engine hardware or software modifications are required.

Dump trucks, wheel loaders, blasting run with HVO from now on

Based on these positive results, Rio Tinto U.S. Borax has continued to work with Rolls-Royce, Neste, the Environmental Protection Agency and the State of California to fully convert its on-site heavy machinery fleet to sustainable diesel by the end of May 2023. This conversion includes all heavy equipment on the site, from haul trucks to wheel loaders, and even blasting.

Notes to editors
* The GHG emission reduction percentage varies depending on the region-specific legislation that provides the methodology for the   calculations (e.g. EU RED II 2018/2001/EU for Europe and U.S. California LCFS for the U.S.), and the raw material mix used to manufacture the product for each market.