GB Railfreight has signed a memorandum of understanding with US clean-energy developer HyOrc. The study will examine converting older diesel locomotives to hydrogen-ready propulsion. The non-binding agreement, branded Project Phoenix, sets out a feasibility pathway rather than a funded programme. It focuses on replacing the diesel power unit in an existing freight locomotive and assessing whether a staged transition from gaseous fuels to hydrogen can be delivered within UK operating and safety requirements.
The concept is based on extending the life of existing traction rather than procuring new hydrogen locomotives. HyOrc’s multi-fuel engine would initially operate on natural gas or LPG before moving to full onboard hydrogen. For UK freight operators, the proposal is framed as a decarbonisation option for non-electrified routes. No prizes for guessing that the target is reducing emissions from the dominant Class 66 fleet.
Retrofit model for international freight markets
HyOrc is developing hydrogen and multi-fuel retrofit programmes for railways in Europe and Asia, alongside its work in stationary power and waste-to-fuel systems. The company’s approach centres on replacing diesel prime movers with gas engines capable of operating on multiple fuels, allowing operators to transition incrementally rather than adopting hydrogen-only traction. This model is intended to reduce capital exposure while maintaining fleet availability during conversion. Although GBRf has already pioneered introducing modern bi-mode locomotives to the UK freight scene, it shares the industry reliance on diesel motive power – particularly the ageing but still viable Class 66 marque, originally developed in the 1990s and manufactured by the then EMD company in North America.
The proposed UK pilot would scale HyOrc’s one-megawatt factory system, independently assessed by Bureau Veritas (a long-established agency), to a three-megawatt locomotive installation. Project Phoenix would examine integration, performance and fuel storage, as well as the commercial case for retrofitting in a market dominated by ageing North American-designed locomotives. HyOrc argues that onboard hydrogen conditioning improves efficiency and reduces the cost penalty associated with compressed hydrogen supply.
Technical scope and staged fuel transition
Under the staged concept, converted locomotives would first operate on natural gas or LPG to deliver immediate emissions reductions. A later phase would introduce fully onboard hydrogen, once supply chains and infrastructure mature. The partners say this phased approach reduces technical risk compared with a single-step transition and allows operational learning before committing to full hydrogen deployment.
Testing would focus on route availability, range, refuelling logistics and maintenance requirements within UK loading gauge constraints. Safety certification for onboard gas and hydrogen storage will be a central element of the feasibility work. The study will also consider whether converted locomotives can match the duty cycles and tractive effort currently provided by diesel traction on heavy freight flows.
Fleet strategy and decarbonisation targets
The initiative sits alongside GB Railfreight’s introduction of Class 99 bi-mode locomotives, which draw primary power from overhead lines and use an HVO-ready diesel engine off-wire. “Project Phoenix aligns with GBRf’s strategic commitment to lead the rail freight sector towards a more sustainable future and could play a key role in delivering our carbon reduction plan,” said Alex Kirk, Commercial Director at GB Railfreight. “By retrofitting part of our existing fleet with multi-fuel technology, it will offer a practical, low-risk route to decarbonisation. It enables us to extend the value of current assets alongside the introduction of our new fleet of bi-mode Class 99s.”
For GBRf, the study addresses the continued reliance on Class 66 locomotives, which remain the mainstay of UK freight but do not meet modern emissions standards. Retrofitting a subset of these units could provide an interim pathway while electrification and alternative traction develop. The operator has consistently argued that network electrification alone will not deliver freight decarbonisation within the required timescales.
Funding pathway and next steps
HyOrc said it is exploring structured funding through the Connected Places Catapult accelerator programme, which supports demonstrator projects for low-carbon transport technologies. “Project Phoenix is a turning point for the rail industry,” said Lisa Carter, CFO of HyOrc. “By retrofitting existing assets, we allow operators to decarbonise immediately, bypassing billions in new fleet costs. We are exploring obtaining structured funding through the [Uk government backed] Connected Places Catapult Accelerator.”
As an MoU, the agreement establishes a framework for technical and commercial evaluation rather than a confirmed conversion. Any demonstrator will depend on funding, regulatory approval and a viable business case. If progressed, the project could test a retrofit model for reducing emissions from diesel-dominated freight fleets on routes where electrification remains unlikely in the medium term.