Rolls-Royce Power Systems has switched key mtu diesel engine test benches in Germany from fossil diesel to hydrogenated vegetable oil (HVO), with the company saying the move reduced CO₂ emissions by around 3,200 tonnes by the end of 2025.

The company said engine testing at its Friedrichshafen, Augsburg and Ruhstorf sites is now being carried out using renewable diesel, produced from vegetable oils and waste materials.

The transition began with initial test runs in September 2024, with additional facilities moving across during the following year. By the end of 2025, Rolls-Royce said the key mtu Series 4000 diesel engines for ships, trains and energy systems were all being tested with HVO in Germany.

At Friedrichshafen, the company said the switch reduced CO₂ emissions from its test benches by about 25% in 2025 compared with fossil-diesel operation. Rolls-Royce expects further savings in 2026, when the facilities will be running on sustainable fuel for the full year.

Nicholas Templin, Executive Vice President of Production, Logistics and Quality Management at Rolls-Royce Power Systems, commented: “Decarbonising our operations is a clear corporate priority for us. Through our solutions, we are also supporting our customers’ sustainability goals. The switch to HVO is an important step towards even more sustainable manufacturing of our products. Our experience has been entirely positive: using HVO makes the production of our products even more sustainable and has proven its worth in operational use.”

According to the company, the average price difference between HVO and B7 diesel in 2025 was around 10 cents per litre.

Rolls-Royce also highlighted additional environmental benefits from HVO use, saying the fuel burns more cleanly and can cut particulate emissions by more than 40% and nitrogen oxide emissions by up to 8%. Depending on the feedstock and production route, lifecycle CO₂ emissions can be reduced by up to 90% compared with fossil diesel.

The company has been testing and approving key mtu engine series for HVO and other sustainable fuels compliant with DIN EN 15940 since 2021. It said HVO can replace fossil diesel without technical modifications to the engines.

Rolls-Royce added that a number of customers are already using HVO with mtu engines in applications including trains, ships, mining equipment, data centres and energy systems.

The company said it continues to support customers adopting HVO, from product selection through to advice on technical and regulatory issues.