Before converting its entire fleet to HVO, the Boron mine ran tests for 2,000 hours with mtu engines on haul trucks. (Photo: Rio Tinto)

Rio Tinto has completely switched heavy machinery at its Boron mine in California from petroleum-derived 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 haul trucks and wheel loaders since 2022. During the 2,000 hours of operation to date, Rio Tinto found that the engines running on renewable diesel deliver similar performance and reliability to traditional diesel.

The switch to renewable diesel at the Boron mine is expected to reduce CO2 by up to 45,000 metric tons per year, equivalent to annual emissions from about 9,600 cars.

The initial trial to convert a Borax haul truck to renewable diesel was conducted in collaboration with fuel manufacturer Neste. The mine used Neste MY Renewable Diesel during the trial, which is made from sustainably sourced, 100% renewable raw materials such as waste cooking oil and animal fat waste and can reduce greenhouse gas emissions by up to 75% over the lifecycle of the fuel compared to conventional diesel.

Other benefits of renewable diesel include clean combustion with a reduction in particulate emissions of up to 40% in mobile applications and a reduction in NOx emissions by an average of 8%. HVO is a drop-in fuel, according to Rolls-Royce, which means that the existing diesel plant infrastructure can be used unchanged for its use, and no engine hardware or software modifications are required.