Rolls-Royce switches to HVO for vessel engine testing

Rolls-Royce Power Systems has moved its mtu diesel engine testing operations in Germany onto hydrogenated vegetable oil (HVO), saving around 3,200 tonnes of CO2 by the end of 2025 and demonstrating that meaningful emissions reductions in engine manufacturing are achievable without major operational disruption.

The move is a practical illustration of HVO's growing role not just as a fuel for vessels in service, but as a drop-in alternative across the wider industrial and maritime supply chain.

Testing at the company's facilities in Friedrichshafen, Augsburg, and Ruhstorf now runs on HVO rather than fossil diesel. The transition began with initial test runs in September 2024 and expanded progressively until all key mtu Series 4000 engines, used in ships, trains, and energy systems, were being tested on HVO. At the Friedrichshafen site alone, CO2 emissions from test benches fell by around 25% in 2025 compared to the previous year's fossil diesel operation. With full-year HVO use now in place across all sites, further reductions are expected through 2026.

Beyond carbon, HVO burns more cleanly than conventional diesel. Particulate emissions fall by 40% or more, and nitrogen oxide emissions reduce by up to 8%. When the full lifecycle is taken into account, from production through to combustion, CO2 emissions from HVO can be up to 90% lower than fossil diesel, depending on the feedstock and production method used.

A key practical advantage is that no engine modifications are required. Rolls-Royce has been approving its mtu engine series for HVO and other fuels meeting the DIN EN 15940 standard since 2021, meaning the fuel can be adopted as a straightforward drop-in replacement. The cost premium over standard diesel averaged just 10 cents per litre in 2025, which compares well with other alternative fuel options currently available at scale.

The switch at Rolls-Royce's testing facilities reflects a broader pattern of HVO adoption across industries. Rail operator Deutsche Bahn has run its vehicles on sustainable fuel since 2022. Swedish data centre operator Eco Datacenter uses HVO to power its emergency generators. Mining group Rio Tinto now fuels dump trucks at large sites in California and Australia with the same fuel. In each case, the ability to substitute HVO without hardware changes has been central to the decision.

For the maritime sector specifically, the mtu Series 4000 engines being tested on HVO are the same engines powering vessels across a range of applications. Rolls-Royce's own testing programme strengthens the evidence base for operators considering HVO as part of their compliance and decarbonisation planning.

 

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