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Czech Railways has entered a new phase in its decarbonization strategy by launching real-world trials of renewable HVO biofuel on RegioFox diesel multiple units, positioning regional rail as a cleaner option for everyday travelers across Central Bohemia.
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From Laboratory Trials to Regular Passenger Service
The current tests are the culmination of several years of research into hydrogenated vegetable oil, or HVO, a renewable fuel produced from waste fats and vegetable oils. Initial engine-bench and track tests were carried out at the Velim railway test centre, where RegioFox trains were run on conventional diesel and different blends of HVO to compare performance, emissions and fuel consumption in controlled conditions.
Following these technical trials, Czech Railways introduced a 20 percent HVO blend into regular operations in April 2025 on RegioFox units serving the Rakovník–Beroun and Beroun–Rudná u Prahy–Prague routes. Publicly available information shows that these services used a fuel marketed as Optimal Diesel PRO with a 20 percent HVO share, supplied by Czech state fuel company ČEPRO, and operated without significant technical issues over the first months of service.
According to published coverage, evaluations of the 20 percent blend indicated slightly higher fuel consumption than standard diesel, but without negative impacts on vehicle components or refueling infrastructure. The data provided a baseline for emissions reductions and operational behavior, paving the way for more ambitious testing of higher HVO concentrations in passenger service.
On the back of these results, Czech Railways has now moved ahead with trials of fully biogenic HVO fuel in the same RegioFox fleet, shifting the project from incremental blending toward a scenario in which diesel trains could eventually run on 100 percent renewable fuel on selected regional lines.
Testing 100 Percent Renewable HVO on Regional Lines
Reports from early September 2026 indicate that three RegioFox units in Central Bohemia are now being fueled with 100 percent HVO in regular passenger service. The pilot is focused on regional routes west of Prague, including lines where the earlier 20 percent blend was introduced, creating a direct comparison between partial and full substitution of fossil diesel.
Information from Czech Railways and specialist rail media describes the rollout as an extension of the original three-phase project. After bench tests and controlled-track trials, followed by real-world operation on a 20 percent blend, the operator is now assessing how fully biogenic HVO behaves under the stresses of daily timetabled service, varying weather conditions and typical regional passenger loads.
The trials make use of RegioFox class 847 units equipped with MTU Rolls-Royce Stage V diesel engines certified for operation with HVO. This certification allows the trains to switch fuels without major hardware modifications, a factor that reduces upfront investment and shortens the timeline between experimental projects and real-world deployment on passenger routes.
Publicly available information suggests that the 100 percent HVO phase will focus on monitoring reliability, cold-weather performance, maintenance needs and detailed emissions data. The results are expected to inform future procurement strategies for diesel fuel on non-electrified routes and may help determine where renewable fuels can complement or bridge to long-term electrification and battery projects.
Environmental Ambitions and EU Policy Context
The HVO program forms part of a wider decarbonization strategy at Czech Railways, which has set out environmental objectives in its recent annual and sustainability reports. Diesel traction remains necessary on many non-electrified regional lines, so reducing the carbon footprint of existing fleets is a key priority alongside investments in electrification and alternative propulsion technologies.
Hydrogenated vegetable oil is considered an advanced biofuel when produced from waste and residue feedstocks. Published coverage notes that, over the full life cycle, HVO can achieve substantial greenhouse gas reductions compared with conventional diesel, while being used in current diesel engines and fueling infrastructure with limited adjustments.
The project also aligns with the European Union’s Renewable Energy Directive targets for transport, which call for higher shares of renewable energy and significant cuts in greenhouse gas emissions by 2030. Czech Railways’ testing of HVO on regional passenger services reflects an effort to meet these obligations in a segment where full electrification is not yet technically or economically feasible.
Public documents from the company emphasize that renewable fuels are being pursued alongside other measures such as more efficient rolling stock, eco-driving, and investments in low- and zero-emission technologies. In this context, the RegioFox HVO trials are one visible component of a broader shift in how regional rail services are powered in the Czech Republic.
Partnerships Behind the HVO Pilot
The renewable fuel trials are supported by a network of partners from the energy, manufacturing and research sectors. Earlier phases of the project involved collaboration with energy group ORLEN Unipetrol, the Railway Research Institute (VUZ), the Czech Technical University’s Centre for Sustainable Mobility Vehicles and train manufacturer PESA, which supplies the RegioFox units.
At the Velim test centre, engineers conducted repeated runs with different HVO blends, loading the trains to simulate real passenger conditions. Reports indicate that these test cycles generated detailed data on performance, exhaust emissions and fuel use, which were then used to select the optimal blend for the first phase of commercial operation.
In later stages, regional authorities in Central Bohemia and Prague participated as ordering bodies for the services operating on HVO-containing fuels. The latest phase, using 100 percent HVO, also relies on supply from fuel providers capable of delivering sufficient volumes of biogenic fuel that meets technical specifications for rail traction use.
This mix of partners illustrates how decarbonizing regional rail requires coordination across the value chain, from rolling stock design and certification to fuel production, distribution and long-term service planning on specific routes.
What the Trials Could Mean for Future Regional Travel
For passengers, the shift to HVO is designed to be largely invisible. Timetables, ticketing and onboard services remain unchanged, while any differences in engine sound or exhaust odor are subtle. The main impacts are environmental, in the form of reduced lifecycle greenhouse gas emissions compared with fossil diesel, and strategic, as the operator gains experience with low-carbon fuels in day-to-day operations.
If the 100 percent HVO trials confirm earlier findings on reliability and emissions, Czech Railways will have a tested pathway to cut the climate impact of diesel services without waiting for full network electrification. That could be particularly significant for rural and regional lines where passenger volumes do not yet justify large-scale infrastructure upgrades.
The project may also provide a reference point for other European rail operators exploring renewable fuels for non-electrified networks. Experience gathered in Central Bohemia, from supply logistics to maintenance regimes, could help shape broader deployment of HVO or similar fuels across the region’s rail systems.
For now, the RegioFox trains running on renewable fuel in the Czech countryside signal an emerging approach to cleaner regional travel: combine existing diesel technology with new-generation biofuels, measure the results carefully, and use that evidence to guide the next wave of investments in sustainable mobility.
Czech Railways press information on 100% HVO testing
iŽeleznice coverage of expanded HVO trials